Arnold Stern, Ph.D., M.D.

Retrospective Chart Review to Correlate Airborne Allergen Skin Test Results with Biopsy Documented Esophageal Eosinophil Count in Eosinophilic Esophagitis (EOE)
Bassett, C. W.; Rothstein, E.; Kopyltsova, Y.; Stern, A.
2010 FEB ;125(2):AB161-AB161, Journal of allergy & clinical immunology
— id: 113922, year: 2010, vol: 125, page: AB161, stat: Journal Article,

Regulatory Effects of Nitric Oxide on Src Kinase, FAK, p130Cas, and Receptor Protein Tyrosine Phosphatase Alpha (PTP-alpha): A Role for the Cellular Redox Environment
Curcio, MF; Batista, WL; Linares, E; Nascimento, FD; Moraes, MS; Borges, RE; Sap, J; Stern, A; Monteiro, HP
2010 JUL ;13(2):109-125, Antioxidants & Redox Signaling
The role of NO in regulating the focal adhesion proteins, Src, FAK, p130 Cas, and PTP-alpha, was investigated. Fibroblasts expressing PTP-alpha (PTP-alpha(WT) cells), fibroblasts 'knockout'' for PTP-alpha (PTP-alpha(-/-) cells), and 'rescued'' 'knockout'' fibroblasts (PTP-alpha A5/3 cells) were stimulated with either S-nitroso-N-acetylpenicillamine (SNAP) or fetal bovine serum (FBS). FBS increased inducible NO synthase in both cell lines. Activation of Src mediated either by SNAP or by FBS occurred independent of dephosphorylation of Tyr527 in PTP-alpha(-/-) cells. Both stimuli promoted dephosphorylation of Tyr527 and activation of Src kinase in PTP-alpha(WT) cells. NO-mediated activation of Src kinase affected the activities of FAK and p130Cas and was dependent on the expression of PTP-alpha. Analogous to tyrosine phosphorylation, SNAP and FBS stimulated differential generation of NO and S-nitrosylation of Src kinase in both cell lines. Incubation with SNAP resulted in higher levels of NO and S-nitrosylation of immunoprecipitated Src in PTP-alpha(-/-) cells (oxidizing redox environment) as compared with the levels of NO and S-nitrosylated Src in PTP-alpha(WT) cells (reducing redox environment). SNAP differentially stimulated cell proliferation of both cell lines is dependent on the intracellular redox environment, Src activity, and PTP-alpha expression. This dependence also is observed with FBS-stimulated cell migration. Antioxid. Redox Signal. 13, 109-125
— id: 110121, year: 2010, vol: 13, page: 109, stat: Journal Article,

Reelin is a platelet protein and functions as a positive regulator of platelet spreading on fibrinogen
Tseng, Wei-Lien; Huang, Chien-Ling; Chong, Kowit-Yu; Liao, Chang-Huei; Stern, Arnold; Cheng, Ju-Chien; Tseng, Ching-Ping
2010 Feb;67(4):641-653, Cellular & molecular life sciences: CMLS
Abnormalities of platelet functions have been linked to reelin-impaired neuronal disorders. However, little attention has been given to understanding the interplay between reelin and platelet. In this study, reelin was found to present in the human platelets and megakaryocyte-like leukemic cells. Reelin-binding assays revealed that extracellular reelin can interact with platelets through the receptor belonging to the low density lipoprotein receptor gene family. The reelin-to-platelet interactions enhance platelet spreading on fibrinogen concomitant with the augmentation of lamellipodia formation and F-actin bundling. In contrast, reelin has no effect on integrin alphaIIbbeta3 activation and agonist-induced platelet aggregation. Molecular analysis revealed that the up-regulation of Rac1 activity and the inhibition of protein kinase C delta-Thr505 phosphorylation are important for reelin-mediated enhancement of platelet spreading on fibrinogen. These findings demonstrate for the first time that reelin is present in platelets and the reelin-to-platelet interactions play a novel role in platelet signaling and functions
— id: 134427, year: 2010, vol: 67, page: 641, stat: Journal Article,

Ethical responsibility of phase 0 trials
Arai, Roberto Jun; Hoff, Paulo Marcelo Gehm; de Castro, Gilberto Jr; Stern, Arnold
2009 Feb 1;15(3):1121-1121, Clinical cancer research
— id: 133655, year: 2009, vol: 15, page: 1121, stat: Journal Article,

MALDI Imaging and LCMS Identification of Colon Cancer Biomarkers in Benign Polyps and Normal Tandem Mucosa
Imanpour, J; Pevsner, P; Kachalov, V; Mathur, S; Moore, H; Melamed, J; Remsen, T; Kanaparthi, C; Mujtaba, G; Kothiya, P; Momin, Z; Vasani, N; Sobel, N; Oprihory, J; Francois, F; Momeni, M; Stern, A; Anand, S
2009 OCT ;104(2):S575-S575, American journal of gastroenterology
— id: 106467, year: 2009, vol: 104, page: S575, stat: Journal Article,

SOMOSAT: Utility of a web-based self-assessment tool in undergraduate medical education
Leaf, David E; Leo, Joseph; Leaf, David E; Leo, Joseph; Smith, Phillip R; Yee, Herman; Stern, Arnold; Rosenthal, Pamela B; Cahill-Gallant, Eileen B; Pillinger, Michael H
2009 May;31(5):e211-e219, Medical teacher
BACKGROUND: Relatively few studies have rigorously assessed the effectiveness of computer-based self-assessment in medical education. AIM: To assess whether an online self-assessment tool can be an effective adjunct to a traditional curriculum for second-year medical students. METHODS: The NYU School of Medicine Online Self-Assessment Tool (SOMOSAT) consists of >450 multiple-choice questions spanning disciplines of internal medicine, administered as separate modules focused on individual organ systems. Questions are coded on multiple dimensions, permitting second-year medical students to receive low-stakes, highly specific feedback regarding their knowledge and performance. Students can also review their answers to guide future study. We employed data collected during SOMOSAT operation to assess its utility and effectiveness. RESULTS: Overall, SOMOSAT accurately predicted student performance on future exams. SOMOSAT participants generally performed better than non-participants on subsequent graded course examinations (p < 0.05). Students using SOMOSAT subsequently experienced greater improvement in areas in which they initially performed poorly, compared with those in which they initially performed well. Students reported that SOMOSAT was most helpful in filling knowledge gaps, and providing opportunities to practice exam-style questions. CONCLUSION: The ability of SOMOSAT to enhance learning and exam performance suggests that web-based self-assessment tools can be effective adjuncts to traditional educational methods
— id: 103162, year: 2009, vol: 31, page: e211, stat: Journal Article,

Mass spectrometry MALDI imaging of colon cancer biomarkers: a new diagnostic paradigm
Pevsner, Paul H; Melamed, Jonathan; Remsen, Tiffany; Kogos, Alexander; Francois, Fritz; Kessler, Paul; Stern, Arnold; Anand, Sury
2009 Feb;3(1):55-69, Biomarkers in medicine
Colorectal cancer (CRC), is the second-leading cause of cancer-related deaths in the USA, affecting both men and women. Current projections show little or no change since the publication of a morbidity and mortality study in 2005. The projected number of new cases for 2008 is 154,000, and the projected number of CRC cancer deaths for 2008 is 53,000. The standard diagnostic paradigm is based on histopathology of either biopsy or surgical specimens. This article suggests a new paradigm for colon cancer diagnosis and staging using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS or IMS). IMS may identify potential tumors in normal tissue of cancer patients and predict those cancer patients who are at risk for recurrent cancer
— id: 110097, year: 2009, vol: 3, page: 55, stat: Journal Article,

Mass Spectrometry MALDI Imaging and LCMS Identification of Colon Cancer Proteins in Benign Polyps
Pevsner, PH; Melamed, J; Kogos, A; Remsen, T; Francois, F; Imanpour, J; Mathur, S; Kachalov, V; Kanaparthi, C; Kessler, P; Moore, HG; Stern, A; Momeni, M; Anand, S
2009 ;136(5):A303-A303, Gastroenterology
— id: 110784, year: 2009, vol: 136, page: A303, stat: Journal Article,

Thioredoxin-1 promotes survival in cells exposed to S-nitrosoglutathione: Correlation with reduction of intracellular levels of nitrosothiols and up-regulation of the ERK1/2 MAP Kinases
Arai, Roberto J; Ogata, Fernando T; Batista, Wagner L; Masutani, Hiroshi; Yodoi, Junji; Debbas, Victor; Augusto, Ohara; Stern, Arnold; Monteiro, Hugo P
2008 Dec 1;233(2):227-237, Toxicology & applied pharmacology
Accumulating evidence indicates that post-translational protein modifications by nitric oxide and its derived species are critical effectors of redox signaling in cells. These protein modifications are most likely controlled by intracellular reductants. Among them, the importance of the 12 kDa dithiol protein thioredoxin-1 (TRX-1) has been increasingly recognized. However, the effects of TRX-1 in cells exposed to exogenous nitrosothiols remain little understood. We investigated the levels of intracellular nitrosothiols and survival signaling in HeLa cells over-expressing TRX-1 and exposed to S-nitrosoglutahione (GSNO). A role for TRX-1 expression on GSNO catabolism and cell viability was demonstrated by the concentration-dependent effects of GSNO on decreasing TRX-1 expression, activation of caspase-3, and increasing cell death. The over-expression of TRX-1 in HeLa cells partially attenuated caspase-3 activation and enhanced cell viability upon GSNO treatment. This was correlated with reduction of intracellular levels of nitrosothiols and increasing levels of nitrite and nitrotyrosine. The involvement of ERK, p38 and JNK pathways were investigated in parental cells treated with GSNO. Activation of ERK1/2 MAP kinases was shown to be critical for survival signaling. In cells over-expressing TRX-1, basal phosphorylation levels of ERK1/2 MAP kinases were higher and further increased after GSNO treatment. These results indicate that the enhanced cell viability promoted by TRX-1 correlates with its capacity to regulate the levels of intracellular nitrosothiols and to up-regulate the survival signaling pathway mediated by the ERK1/2 MAP kinases
— id: 133605, year: 2008, vol: 233, page: 227, stat: Journal Article,

The low molecular weight S-nitrosothiol, S-nitroso-N-acetylpenicillamine, promotes cell cycle progression in rabbit aortic endothelial cells
Oliveira, CJR; Curcio, MF; Moraes, MS; Tsujita, M; Travassos, LR; Stern, A; Monteiro, HP
2008 JUN ;18(4):241-255, Nitric oxide : biology & chemistry
S-Nitrosylation reactions are considered to be a major mechanism by which NO-related bioactivities are regulated in vivo. In the present study, we show the effects of the low molecular weight S-nitrosothiol, S-nitroso-N-acetylpenicillamine (SNAP), on cell cycle progression of rabbit aortic endothelial cells (RAEC). SNAP at low concentrations (0.1 mM) stimulated the p21Ras-ERK1/2 MAP kinase signaling pathway. Activation of this signaling pathway was strongly inhibited in cells stably transfected with S-nitrosylation insensitive p21Ras (p21(Ra(C118S))). Furthermore, the SNAP-induced effects on cell cycle progression were eliminated in RAEC expressing N17Ras, a negative dominant mutant of p21Ras. Upon stimulation with SNAP, ERK1/2 MAP kinases become phosphorylated and translocate to the nucleus promoting the phosphorylation of the transcription factor E1k1. Synthesis of Cyclin D1 and stimulation of the cyclin-dependent kinases cdk4 and cdk6 resulted in the phosphorylation of the nuclear protein Rb and its dissociation from the E2F family of transcription factors. Cells then pass the restriction point in the late G1 phase. Cyclins E and A were expressed as the cell cycle progressed through the S phase upon stimulation with SNAP. Further transition in the cell cycle from the G2 to M phase was evidenced by the G2/M peak found in a histogram of the cell-phase distribution in SNAP-treated RAEC. These observations suggest that low molecular weight S-nitrosothiols may promote cell cycle progression possibly through the transnitrosation of p21Ras, and activation of the Ras-ERK1/2 MAP kinases signaling pathway. (C) 2008 Elsevier Inc. All rights reserved
— id: 78874, year: 2008, vol: 18, page: 241, stat: Journal Article,

Inflammatory bowel disease (IBD) - Protein profile of active disease
Pevsner, P; Eskaros, S; Melamed, J; Remsen, T; Diamond, I; Francois, F; Momeni, M; Kessler, P; Stern, A; Anand, S
2008 SEP ;103(9):S449-S449, American journal of gastroenterology
— id: 86598, year: 2008, vol: 103, page: S449, stat: Journal Article,

Colon tumor biomarkers-Maldi imaging of tissue microarray
Pevsner, P; Melamed, J; Remsen, T; Duddempudi, S; Francois, F; Momeni, M; Sandar, N; Kessler, P; Stern, A; Anand, S
2008 SEP ;103(9):S196-S197, American journal of gastroenterology
— id: 86597, year: 2008, vol: 103, page: S196, stat: Journal Article,

The nitric oxide-sensitive p21Ras-ERK pathway mediates S-nitrosoglutathione-induced apoptosis
Tsujita, Maristela; Batista, Wagner L; Ogata, Fernando T; Stern, Arnold; Monteiro, Hugo P; Arai, Roberto J
2008 May 16;369(4):1001-1006, Biochemical & biophysical research communications
p21Ras protein plays a critical role in cellular signaling that induces either cell cycle progression or apoptosis. Nitric oxide (NO) has been consistently reported to activate p21Ras through the redox sensitive cysteine residue (118). In this study, we demonstrated that the p21Ras-ERK pathway regulates THP-1 monocyte/macrophage apoptosis induced by S-nitrosoglutathione (SNOG). This was apparent from studies in THP-1 cells expressing NO-insensitive p21Ras (p21Ras(C118S)) where the pro-apoptotic action of SNOG was almost abrogated. Three major MAP kinase pathways (ERK, JNK, and p38) that are downstream to p21Ras were investigated. It was observed that only the activation of ERK1/2 MAP kinases by SNOG in THP-1 cells was attributable to p21Ras. The inhibition of the ERK pathway by PD98059 markedly attenuated apoptosis in SNOG-treated THP-1 cells, but had a marginal effect on SNOG-treated THP-1 cells expressing NO-insensitive p21Ras. The inhibition of the JNK and p38 pathways by selective inhibitors had no marked effects on the percentage of apoptosis. The induction of p21Waf1 expression by SNOG was observed in THP-1 cells harboring mutant and wild-type p21Ras, however in cells expressing mutant Ras, the expression of p21Waf1 was significantly attenuated. The treatment of THP-1 cells expressing wild-type p21Ras with PD98059 resulted in significant attenuation of p21Waf1 expression. These results indicate that the redox sensitive p21Ras-ERK pathway plays a critical role in sensing and delivering the pro-apoptotic signaling mediated by SNOG
— id: 135348, year: 2008, vol: 369, page: 1001, stat: Journal Article,

Regulation of p21Waf1 expression and TNF alpha(biosynthesis by glutathione modulators in PMA induced-THP1 differentiation: Involvement of JNK and ERK pathways
Debbas, V; Arai, RJ; Ferderbar, S; Schindler, F; Stern, A; Monteiro, HP
2007 NOV 30 ;363(4):965-970, Biochemical & biophysical research communications
Oxidative modifications of proteins are fundamental biochemical events that regulate cellular signaling, protein expression, and function. The redox status is balanced by reductants in which GSH plays a major role. This study investigated whether or not p21Waf1 expression and TNF alpha biosynthesis in macrophage differentiation/activation were regulated by GSH modulators and whether or not the JNK and ERK pathway were involved. We observed an increase of p21Waf1 expression and TNF alpha biosynthesis in the THP1 monocyte/macrophage cell line treated with PMA. Treatment of THP1 cultures with NAC prior to adding PMA abrogates the expression of p21Waf1 mRNA and decreases the level of TNF alpha whereas GSH depletion by BSO enhances the levels of TNF alpha with minor effects on p21Waf1 expression. To assess whether or not ERK and JNK were involved in the redox mechanism of p21Waf1 and TNF alpha, we used pharmacological inhibitors for JNK and ERK. Both PD98095 and dicoumarol were capable of blocking TNF alpha production but had only a small effect on p21Waf1 expression. We next observed that activation of JNK was significantly inhibited in cells pretreated with NAC with no effect on ERK. Taken together, our findings suggest that the modulation of GSH regulate the magnitude the cell response to PMA in which JNK and ERK have a particular role in redox signaling, (C) 2007 Elsevier Inc. All rights reserved
— id: 74791, year: 2007, vol: 363, page: 965, stat: Journal Article,

Direct identification of proteins from T47D cells and murine brain tissue by matrix-assisted laser desorption/ionization post-source decay/collision-induced dissociation
Pevsner, Paul H; Naftolin, Frederick; Hillman, Dean E; Miller, Douglas C; Fadiel, Ahmed; Kogus, Alexander; Stern, Arnold; Samuels, Herbert H
2007 ;21(3):429-436, Rapid communications in mass spectrometry
The purpose of this study is to determine the feasibility of the direct matrix-assisted laser desorption/ionization (MALDI) identification of proteins in fixed T47D breast cancer cells and murine brain tissues. The ability to identify proteins from cells and tissue may lead to biomarkers that effectively predict the onset of defined disease states, and their dynamic behavior could be an important hint for drug target discoveries. Direct tissue application of trypsin allows protein identification in cells and tissues, while maintaining spatial integrity and intracellular organization. Using a chemical printer, matrix was co-registered on trypsinized human T47D breast cancer cells and cryo-preserved sections of murine brain tissue, followed by MALDI post-source decay (PSD) or MALDI collision-induced dissociation (CID), respectively. Mass-to-charge (m/z) data from the cells and brain tissues were processed using Mascot software interrogation of the National Center for Biotechnology Information (NCBI) database. Histone H2B was identified from cultured T47D human breast cancer cells. Tubulin beta2 was identified from mouse brain cortex following an induced stroke. These results suggest that MALDI PSD/CID, combined with bioinformatics, can be used for the direct identification of proteins from cells and tissues. Refinements in preparation techniques may improve this approach to provide a tool for quantitative proteomics and clinical analysis
— id: 70734, year: 2007, vol: 21, page: 429, stat: Journal Article,

Nitric oxide induces thioredoxin-1 nuclear translocation: Possible association with the p21Ras survival pathway
Arai, RJ; Masutani, H; Yodoi, J; Debbas, V; Laurindo, FR; Stern, A; Monteiro, HP
2006 OCT 6 ;348(4):1254-1260, Biochemical & biophysical research communications
One of the major redox-regulating molecules with thiol reducing activity is thioredoxin-1 (TRX-1). TRX-1 is a multifunctional protein that exists in the extracellular millieu, cytoplasm, and nucleus, and has a distinct role in each environment. It is well known that TRX-1 promptly migrates to the nuclear compartment in cells exposed to oxidants. However, the intracellular location of TRX-1 in cells exposed to nitrosothiols has not been investigated. Here, we demonstrated that the exposure of HeLa cells to increasing concentrations of the nitrosothiol S-nitroso-N-acetylpenicillamine (SNAP) promoted TRX-1 nuclear accumulation. The SNAP-induced TRX-1 translocation to the nucleus was inhibited by F
— id: 68679, year: 2006, vol: 348, page: 1254, stat: Journal Article,

Disabled-2 is a novel alpha IIb-integrin-binding protein that negatively regulates platelet-fibrinogen interactions and platelet aggregation
Huang, CL; Cheng, JC; Stern, A; Hsieh, JT; Liao, CH; Tseng, CP
2006 NOV 1 ;119(21):4420-4430, Journal of cell science
Platelet aggregation plays a pivotal role in the haemostatic process and is involved in the pathological counterpart of arterial thrombosis. We have shown that the adapter protein disabled-2 (DAB2) is expressed abundantly in platelets. In this study, DAB2 was found to distribute in the platelet alpha-granules and was released from the granular compartment upon platelet activation. The secreted DAB2 binds to the extracellular region of alpha IIb beta 3 integrin on the platelet surface through the phosphotyrosine-binding domain. The DAB2-platelet interactions result in the inhibition of agonist-induced platelet aggregation with the exception of thrombin, a DAB2 protease that renders DAB2 inactive. Biochemical and mutational analysis revealed that the DAB2 cell-adhesion Arg-Gly-Asp (RGD) motif ( amino acid residues 64-66) and the alpha IIb-integrin-fibrinogen-binding region ( amino acid residues 171-464) are important for the DAB2-platelet interactions. Such interactions compete for the binding of alpha IIb integrin with fibrinogen and provide a mechanism for DAB2 to inhibit platelet aggregation. Accordingly, the synthetic RGD-motif-containing DAB2 peptide PDARGDKM also elicited antiplatelet aggregation activity. These findings demonstrate for the first time that DAB2 is an alpha IIb-integrin-binding protein that plays a novel role in the control of platelet-fibrinogen interactions and platelet aggregation
— id: 69302, year: 2006, vol: 119, page: 4420, stat: Journal Article,

Direct matrix assisted laser desorption ionizationmass spectrometry (MALDI-ms) identification of tubulin beta-2 chain and other proteins in murine brain and spinal cord tissue
Pevsner, PH; Naftolin, F; Miller, DC; Kogus, A; Fadiel, A; Hillman, D; Stall, BK; Wishnie, S; Xiang, F; Barnes, A; Stern, A
2006 FEB ;13(2):346A-346A, Journal of the Society for Gynecologic Investigation
— id: 62832, year: 2006, vol: 13, page: 346A, stat: Journal Article,

Minimally invasive method for murine brain fixation
Eichenbaum, Kenneth D; Eichenbaum, Joseph W; Fadiel, Ahmed; Miller, Douglas C; Demir, Necdet; Naftolin, Frederick; Stern, Arnold; Pevsner, Paul H
2005 Oct;39(4):487-8, 490, Biotechniques
Complete brain fixation can be achieved with transthoracic cardiac infusion without thoracotomy. Light and electron microscopy tissue sections reveal preservation of cytoplasmic and nuclear structure at all magnification levels. Punched samples were obtained from the fixed tissue specimens in precisely localized areas for study using electron microscopy. This perfusion fixation technique provides both faster tissue harvesting capability and higher quality tissue preservation, without the artifacts of brain swelling and ventricular dilation observed in direct cardiac perfusion. Acute, discrete change in brain tissue can be studied
— id: 58919, year: 2005, vol: 39, page: 487, stat: Journal Article,

Ethical, legal, and social issues related to genomics and cancer research: the impending crisis
Ellerin, Bruce E; Schneider, Robert J; Stern, Arnold; Toniolo, Paolo G; Formenti, Silvia C
2005 Nov;2(11):919-926, Journal of the American College of Radiology : JACR
Cancer research is a multibillion-dollar enterprise validated by the clinical trial process and increasingly defined by genomics. The continued success of the endeavor depends on the smooth functioning of the clinical trial system, which in turn depends on human subject participation. Yet human subject participation can exist only in an atmosphere of trust between research participants and research sponsors, and the advent of genomics has raised a multitude of ethical, legal, and social issues that threaten this trust. The authors examine 6 of these issues: (1) informed consent; (2) privacy, confidentiality, and family disclosure dilemmas; (3) property rights in genomic discoveries; (4) individual and institutional conflicts of interest; (5) insurance and employment issues; and (6) litigation under the federal False Claims Act. The authors conclude that failure to resolve these issues may lead to a sufficient impairment of trust in genomics-based clinical trials on the part of potential research participants that the clinical trial system may implode for lack of willing participants, thus threatening the future of cancer research
— id: 72043, year: 2005, vol: 2, page: 919, stat: Journal Article,

Disabled-2 is a negative regulator of integrin alpha(IIb)beta(3)-mediated fibrinogen adhesion and cell signaling
Huang, CL; Cheng, JC; Liao, CH; Stern, A; Hsieh, JT; Wang, CH; Hsu, HL; Tseng, CP
2004 OCT 1 ;279(40):42279-42289, Journal of biological chemistry
(D) under bar is (ab) under bar led-(2) under bar ( DAB2) is an adapter protein that is up-regulated during megakaryocytic differentiation of hematopoietic cells and is abundantly expressed in platelets. In this study, the role of DAB2 in integrin alpha(IIb)beta(3)-mediated matrix protein fibrinogen adhesion and cell signaling was investigated. In K562 cells differentiating to the megakaryocytic lineage, down-regulation of DAB2 by DAB2 small interfering RNA augmented integrin alpha(IIb)beta(3) activation and resulted in an increase in cell adhesion to fibrinogen. Ectopic expression of DAB2 reversed the DAB2 small interfering RNA effect or, by itself, decreased fibrinogen adhesion of K562 cells. Mutational analysis revealed that a DAB2 Ser(24) phosphorylation mutant (S24A) abrogated the inhibitory function of DAB2. The spatial and temporal association/interaction of DAB2 and platelet integrin alpha(IIb)beta(3) (CD61) in both megakaryocytic cells and platelets led us to examine the effect of Ser(24) phosphorylation on the interaction between DAB2 and integrin beta(3). Through cellular localization and co-immunoprecipitation analysis, we demonstrate for the first time that Ser(24) phosphorylation promotes membrane translocation of DAB2 and its subsequent interaction with integrin beta(3), thereby defining a mechanism for DAB2 in regulating integrin alpha(IIb)beta(3) activation and inside-out signaling. Consistent with the effect on fibrinogen adhesion, Ser(24) phosphorylation of DAB2 was also involved in the negative regulation of alpha(IIb)beta(3)-induced T cell factor transcriptional activity. In contrast, the S24A mutant acted like wild-type DAB2 and inhibited both beta-catenin- and plakoglobin-mediated T cell factor transactivation. Hence, DAB2 elicits distinct regulatory mechanisms in alpha(IIb)beta(3) and beta-catenin/plakoglobin signaling in a Ser(24) phosphorylation-dependent and -independent manner, respectively. These findings indicate Ser(24) phosphorylation as a molecular basis for DAB2 acting as a negative regulator in alpha(IIb)beta(3) inside-out signaling and contribute to our understanding of DAB2 in megakaryocytic differentiation and platelet function
— id: 46500, year: 2004, vol: 279, page: 42279, stat: Journal Article,

Nitric oxide: a potential inducer of adhesion-related apoptosis-anoikis
Monteiro, HP; Silva, EF; Stern, A
2004 FEB ;10(1):1-10, Nitric oxide : biology & chemistry
Among the many initiating events that lead to apoptosis or programmed cell death, loss of contact between the cell and the extracellular matrix has been extensively studied. Adhesion-related apoptosis referred to as anoikis is initiated by the action of anti-adhesive substances. Nitric oxide is one of these anti-adhesive substances that have the capacity to signal and trigger pro-apoptotic events in a variety of cell types. Nitric oxide can inhibit cell adhesion, interfere with the assembly of focal adhesion complexes, and disrupt the cell-extracellular matrix interactions. These actions occur in cell that exhibit a dissociation of growth factor signals from alterations in the cytoskeleton, ultimately leading to apoptosis. Since this involves anti-adhesive events, nitric oxide can be considered as causing anoikis. This review article summarizes the available evidence of how nitric oxide participates in apoptosis induced by loss of anchorage (anoikis). (C) 2004 Elsevier Inc. All rights reserved
— id: 46653, year: 2004, vol: 10, page: 1, stat: Journal Article,

Palladium and platinum ions interfere with the measurement of erythrocyte vesiculation by inhibiting the acetylcholinesterase activity of the released spectrin-depleted microvesicles
Liu, TZ; Chiu, DTY; Lo, WC; Stern, A
2003 JAN 10 ;72(8):909-916, Life sciences
Palladium (Pd2+) and platinum (Pt2+) ions were found to inhibit erythrocyte membrane-bound acetylcholinesterase (AChE) with Ki values of 6.0 and 6.5 mug/ml, respectively. Lineweaver-Burke plots revealed that the inhibition of erythrocyte AChE by both metal ions was competitive in nature. Binding studies using alkaline phosphatase as a reporting enzyme confirmed that both metal ions indeed did bind to the enzyme molecules. In the process of red cell vesiculation, membrane-bound AChE is shed along with vesicles. The measurement of AChE activities in the medium containing vesiculated RBC could potentially be served as an index of vesiculation. Inhibition of AChE activities by both metal ions can thus constitute a potential source of error in vesiculation measurement. To illustrate these effects, a simulated vesiculation system, using green tea polyphenol in the presence (25 mug/ml) or absence of Pd2+ ion was simultaneously examined by the electronmicrography and the AChE method. We observed vesiculation under the experimental condition in Pd2+-free controls that was associated with a time-dependent increase in AChE activity were barely detected in the Pd2+-spiked specimen because of the masking effect exerted by the metal ions themselves. (C) 2002 Published by Elsevier Science Inc
— id: 55584, year: 2003, vol: 72, page: 909, stat: Journal Article,

Ras nitrosylation and protein phosphorylation in nitric oxide-induced apoptosis
Monteiro, H; Tsujita, M; Arai, R; Stern, A
2003 OCT ;35(11):S70-S71, Free radical biology & medicine
— id: 55393, year: 2003, vol: 35, page: S70, stat: Journal Article,

Nitric oxide and cGMP activate the Ras-MAP kinase pathway-stimulating protein tyrosine phosphorylation in rabbit aortic endothelial cells
Oliveira, CJR; Schindler, F; Ventura, AM; Morais, MS; Arai, RJ; Debbas, V; Stern, A; Monteiro, HP
2003 AUG 15 ;35(4):381-396, Free radical biology & medicine
The free radical nitric oxide is a very effective signal transducer, stimulating the enzyme guanylyl cyclase, the oncoprotein p21Ras, and protein tyrosine phosphorylation. In the present study using rabbit aortic endothelial cells (RAEC), it is demonstrated that the nitric-oxide-generating substances sodium nitroprusside and S-nitroso-N-acetylpenicillamine, and a stable analog of cyclic GMP, 8BrcGMP stimulate p21Ras activity. Tyrosine phosphorylation of cytosolic proteins was stimulated and intracellular production of cGMP was increased, indicating that the NO/cGMP-stimulated tyrosine phosphorylation-dependent signaling pathway is most likely associated with the activation of p21Ras. NO and cGMP-dependent activation of p21Ras result in binding of the oncoprotein to the Ras-binding domain of Raf-1 kinase. Incubation of RAEC with F
— id: 37167, year: 2003, vol: 35, page: 381, stat: Journal Article,

Effects of lipopolysaccharide on low- and high-density cultured rabbit vascular smooth muscle cells: differential modulation of nitric oxide release, ERK1/ERK2 MAP kinase activity, protein tyrosine phosphatase activity, and DNA synthesis
de Oliveira, LCB; Oliveira, CJR; Fries, DM; Stern, A; Monteiro, HP
2002 Feb;35(2):181-190, Brazilian journal of medical & biological research
Previous studies have shown that exogenously generated nitric oxide (NO) inhibits smooth muscle cell proliferation. In the present study, we stimulated rabbit vascular smooth muscle cells (RVSMC) with E. coli lipopolysaccharide (LPS), a known inducer of NO synthase transcription, and established a connection between endogenous NO, phosphorylation/dephosphorylation-mediated signaling pathways, and DNA synthesis. Non-confluent RVSMC were cultured with 0, 5, 10, or 100 ng/ml of the endotoxin. NO release was increased by 86.6% (maximum effect) in low-density cell cultures stimulated with 10 ng/ml LPS as compared to non-stimulated controls. Conversely, LPS (5 to 100 ng/ml) did not lead to enhanced NO production in multilayered (high density) RVSMC. DNA synthesis measured by thymidine incorporation showed that LPS was mitogenic only to non-confluent RVSMC; furthermore, the effect was prevented statistically by aminoguanidine (AG), a potent inhibitor of the inducible NO synthase, and oxyhemoglobin, an NO scavenger. Finally, there was a cell density-dependent LPS effect on protein tyrosine phosphatase (
— id: 27519, year: 2002, vol: 35, page: 181, stat: Journal Article,

A murine photochemical stroke model with histologic correlates of apoptotic and nonapoptotic mechanisms
Eichenbaum, Joseph W; Pevsner, Paul H; Pivawer, Gabriel; Kleinman, George M; Chiriboga, Luis; Stern, Arnold; Rosenbach, Ari; Iannuzzi, Kathryn; Miller, Douglas C
2002 Mar-Apr;47(2):67-71, Journal of pharmacological & toxicological methods
INTRODUCTION: The neuronal cell death that occurs after ischemia-induced cerebral infarction (stroke) contains elements of apoptosis and necrosis, an intermediary form of the two, and a distinct excitotoxic process. We previously developed a photochemical model of stroke in the rat. We have now adapted this model for use in the mouse. The present manuscript describes the mouse model. METHODS: Minimal beam intensity (0.1 W/cm(2)) cold white light (8 min exposure) was used to evoke discrete infarcts in the parietal lobes of 11 mice sensitized by the administration of fresh Rose Bengal (10 mg/kg by rapid iv infusion). RESULTS: At 2 h, five out of five mice and at 6 h, six out of six mice demonstrated light microscopic histologic features like those in the rat model. These included a superior ischemic zone with shrunken and pyknotic nuclei, a middle transition zone of edematous vacuolated neuropil but normal neurons with open chromatin and retained Nissl granules, and an inferior zone with normal neurons. There was widespread nuclear terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling (TUNEL) in the superior infarct zone in 11/11 mice. However, in the edematous vacuolated transition zone, 11/11 mice had TUNEL positive and negative nuclei randomly mixed. Light microscopic analysis of that same transition zone showed no pyknosis or chromatin bodies in the TUNEL positive or negative cells. DISCUSSION: In mice, photoactivation of Rose Bengal evoked similar infarct and transition zone patterns found previously in rats, with TUNEL evidence of apoptotic and nonapoptotic events. Thus, it will be possible to use this model for further quantitative study of apoptotic and excitotoxic events in wild and transgenic mice
— id: 45389, year: 2002, vol: 47, page: 67, stat: Journal Article,

Nitric oxide-mediated activation of the Ras-MAP kinase pathway stimulates tyrosine phosphorylation
Monteiro, HP; Rocha Oli veira, CJ; Ventura, A; Stern, A
2002 MAR 12 ;33(10):153-1287, Free radical biology & medicine
— id: 34086, year: 2002, vol: 33, page: 153, stat: Journal Article,

alpha-Tocopherol modulates tyrosine phosphorylation in human neutrophils by inhibition of protein kinase C activity and activation of tyrosine phosphatases
Chan, SS; Monteiro, HP; Schindler, F; Stern, A; Junqueira, VBC
2001 Mar;35(6):843-856, Free radical research
alpha-Tocopherol augmentation in human neutrophils was investigated for effects on neutrophil activation and tyrosine phosphorylation of proteins, through its modulation of protein kinase C (PKC) and tyrosine phosphatase activities. Incubation of neutrophils with alpha-tocopherol succinate (TS) resulted in a dose-dependent incorporation into cell membranes, up to 2.5 nmol/2 X 10(6) cells. A saturating dose of TS (40 mumol/l) inhibited oxidant production by neutrophils stimulated with phorbol myristate acetate (PMA) or opsonized zymosan (OZ) by 86 and 57%, as measured by luminol-amplified chemiluminescence (CL). With PMA, TS inhibited CL generation to a similar extent to staurosporine (10 nmol/l) or genistein (100 mumol/l), and much more than Trolox (40 mumol/l). With OZ, TS inhibited CL to a similar extent to Trolox. Neutrophil PKC activity was inhibited 50% or more by TS or staurosporine. The enzyme activity was unaffected by genistein or Trolox, indicating a specific interaction of alpha-tocopherol. TS or Trolox increased protein tyrosine phosphorylation in resting neutrophils, and as with staurosporine further increased tyrosine phosphorylation in PMA-stimulated neutrophils, while the tyrosine kinase (TK) inhibitor genistein diminished phosphorylation. These effects in resting or PMA-stimulated neutrophils were unrelated to protein tyrosine phosphatase (
— id: 27509, year: 2001, vol: 35, page: 843, stat: Journal Article,

Diethylenetriaminopentaacetic acid is unsuitable for long-term preservation of RBCs
Liu, TZ; Chiu, DTY; Stern, A
2001 APR ;41(4):556-559, Transfusion
BACKGROUND: The addition of an appropriate metal chelator, such as diethylenetriaminopentaacetic acid (DTPA) to stored blood has been shown to be effective in a short-term (0-12 days) prevention of lipid peroxidation of stored RBCs. However, its long-term effectiveness has not been carefully evaluated. STUDY DESIGN AND METHODS: Blood was preserved in simulated blood bank conditions with or without the addition of DTPA for 4 weeks. Aliquots of stored blood were taken weekly from the storage bag and the deformability profile was determined using a custom-built laser viscodiffractometer. Malondialdehyde (MDA), an index of lipid peroxidation, and the extent of vesiculation of the stored blood were quantified concurrently. RESULTS: It was found that MDA values for DTPA-supplemented blood at the end of a 28-day storage period were significantly elevated compared with the DTPA-free counterpart (23.50 +/- 3.2 vs. 16.10 +/- 2.5 muM; p <0.05). In addition, DTPA-supplemented blood was more susceptible to vesiculation than its DTPA-free counterpart (31.26 +/- 4.1 vs. 10.26 +/- 1.5% of acetyl cholinesterase release, p <0.001). These data are also in accordance with the finding of the deformability profile result, indicating that DTPA-supplemented blood exhibits not only a decrease in deformability index, but also a tendency to shift the profile to a lower osmolality compared with that of controls (a dehydration phenomenon). CONCLUSION: Long-term (0-28 days) preservation of human RBCs with DTPA caused a gradual increase in MDA production, a progressive enhancement of the severity of vesiculation, and an alteration in the deformability profile. Free-radical-mediated oxidative damage is likely to be the culprit for this observed phenomenon. In addition, the direct effect of DTPA on RBC structural integrity must be considered.
— id: 55088, year: 2001, vol: 41, page: 556, stat: Journal Article,

Free radical-triggered hepatic injury of experimental obstructive jaundice of rats involves overproduction of proinflammatory cytokines and enhanced activation of nuclear factor kappa B
Liu, TZ; Lee, KT; Chern, CL; Cheng, JT; Stern, A; Tsai, LY
2001 OCT ;31(4):383-390, Annals of clinical & laboratory science
Excessive production of hydroxyl radicals in blood and liver has previously been demonstrated by us in rats with obstructive jaundice induced by common bile duct ligation (CBDL). In this study, we demonstrate overproduction of superoxide radicals in circulating blood of CBDL rats by the lucigenin-amplified chemiluminescence technique. To pinpoint the molecular agents that mediate these processes, we measured circulating proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin- 1 beta (IL-1 beta), and interleukin-6 (IL-6) in controls and CBDL rats. Concentrations of these cytokines in blood of CBDL rats were markedly elevated when compared to the controls (TNF-alpha: 36.7+/-5.0 vs 13.8+/-0.5 pg/mL; IL-6: 2,814+/-1,740 vs 0 pg/mL; IL-1 beta: 11.9+/-2.6 vs 0 pg/mL). The overproduction of free radicals triggered by elevated cytokines in CBDL rats was correlated with the activation of NF-kappaB in hepatic tissue. Using the TdT-mediated dUTP nick-end label staining technique, we showed that hepatic tissue sections from CBDL rats had an increase in the apoptotic index (AI). Based on these findings, we propose that the severe hepatic injury in CBDL rats is mediated by a cycle that involves the activation of NF-kappaB by combined action of proinflammatory cytokines and reactive oxygen species (ROS). NF-kappaB, in turn, initiates the transcription of cytokine genes (eg, IL-6, IL-8, TNF-alpha), which triggers hepatic injury, at least in part, by a free radical-mediated apoptotic mechanism. Elevated ROS may be as a positive feedback signal that triggers NF-kappaB reactivation; the severe hepatic injury of CBDL rats may result from perpetuation of this vicious cycle
— id: 54815, year: 2001, vol: 31, page: 383, stat: Journal Article,

A photothrombotic model of small early ischemic infarcts in the rat brain with histologic and MRI correlation
Pevsner PH; Eichenbaum JW; Miller DC; Pivawer G; Eichenbaum KD; Stern A; Zakian KL; Koutcher JA
2001 May-Jun;45(3):227-233, Journal of pharmacological & toxicological methods
Over the last two decades several studies have suggested the role of photothrombotic occlusion of cerebral microvessels using rose bengal, resulting in small strokes in rodents that resemble those in humans. This paper describes such a photothrombotic method of acute small stroke induction in rats with histopathologic and in vivo magnetic resonance imaging (MRI) observations from 3 to 6 h after irradiation, which is homologous to a human autopsy specimen. Utilizing 30 min of irradiation with minimal beam intensity (0.1 W/cm(2)) cold white light in conjunction with 20 mg of intravenous (iv) rose bengal as a rapid infusion, small infarcts were induced photochemically in the frontal lobes of six rats. The infarcts showed a consistent pattern on histologic and in vivo MR sections when examined within 7 h or less of irradiation. Both MRI and histologic sections were comprised of (a) a superior zone of infarcted neurons, (b) a middle curvilinear transition zone of edema on MRI and histologically vacuolated neuropil, and (c) an inferior zone of normal neurons. Shorter duration water-sensitive (T2)- and postgadolinium longer duration (T1)-weighted signal decay images both showed a curvilinear hyperintense transition zone of edema. The mean infarct and transition zone areas measured from the histologic sections were comparable to those measured on the MRI. The infarct model described above allows in vivo observations using MRI with the potential for use in testing putative neuroprotective agents. As demonstrated by a comparison with the histologic features of such infarcts in surgical and autopsy brain specimens, the model is relevant to acute human ischemic infarcts
— id: 25660, year: 2001, vol: 45, page: 227, stat: Journal Article,

Rapid and specific detection of hydroxyl radical using an ultraweak chemiluminescence analyzer and a low-level chemiluminescence emitter: Application to hydroxyl radical-scavenging ability of aqueous extracts of food constituents
Tsai, CH; Stern, A; Chiou, JF; Chern, CL; Liu, TZ
2001 MAY ;49(5):2137-2141, Journal of agricultural & food chemistry
With the availability of;an ultraweak chemiluminescence analyzer, it is possible to monitor the production of a specific oxygen-derived reactive species; such as hydroxyl radical ((OH)-O-.), whenever a suitable chemiluminescent probe is obtainable. Reported herein is the development of a rapid and specific method for detecting (OH)-O-. production using a specific probe, indoxyl-P-glucuronide (IBG), a low-level chemiluminescence emitter. Using the Fenton reagent as a source of (OH)-O-., it was shown that IBG could elicit a very strong intensity of chemiluminescence (CL) (16200 +/- 200 photon counts/s). Conversely, IBG was shown to be insensitive to either superoxide radical or hydrogen peroxide. with their CL intensities nearly close to the background values (25 +/- 5 and 180 +/- 20 photon counts/s, respectively). Furthermore, it was also shown that this IBG-based CL production could be effectively quenched by the addition of (OH)-O-. scavengers such as sodium salicylate, dimethyl sulfoxide, and penicillamine to the assay system. Taken together, these data indicate that IBG is a specific CL probe suitable for monitoring the production of (OH)-O-.; This system demonstrated inhibitory activities of various aqueous extracts of food constituents on the CL of hydroxyl radicals generated by Fenton's reagents with the order of scavenging efficiencies being Prunus mume > Cordyceps sinensin > Lilium lancifolium > Astragalus membranceus
— id: 55054, year: 2001, vol: 49, page: 2137, stat: Journal Article,

Inhibition of cell proliferation in HCC-9204 hepatoma cells by a c-myc specific ribozyme
Cheng J; Luo J; Zhang X; Hu J; Hui H; Wang C; Stern A
2000 Mar;7(3):407-412, Cancer gene therapy
A ribozyme (RZ) gene targeting c-myc mRNA was synthesized and cloned. Cleavage reaction showed that cleavage of the RZ was efficient and specific. The RZ gene-containing retrovirus vector pDOR-RZ was transfected into HCC-9204 hepatoma cells, which constitutively express high levels of c-myc using Lipofectamine. Positively transfected cells were selected using G418. In situ hybridization showed that both pDOR-RZ and pDOR vectors had been integrated into the chromosome of HCC-9204 cells. Dot blot hybridization indicated that expression of the RZ was only evident in pDOR-RZ-transfected HCC-9204 cells. Avidin-biotin complex enzyme-linked immunosorbent assay showed that c-myc expression was down-regulated. Chromatin aggregation into compact masses, cytoplasmic vacuole degeneration, and blurring of cytoplasm structure were observed by transmission electron microscopy in HCC-9204-RZ cells. These results suggest that the use of a c-myc mRNA cleaving enzyme could be most effective in tumor cells that are highly proliferative and constitutively express high levels of c-myc
— id: 11752, year: 2000, vol: 7, page: 407, stat: Journal Article,

Cellular glucose-6-phosphate dehydrogenase (G6PD) status modulates the effects of nitric oxide (NO) on human foreskin fibroblasts
Cheng, ML; Ho, HY; Liang, CM; Chou, YH; Stern, A; Lu, FJ; Chiu, DT
2000 JUN 23 ;475(3):257-262, FEBS letters
Glucose-6-phosphate dehydrogenase (G6PD) plays an important role in cellular redox homeostasis, which is crucial for cell survival. In the present study, we found that G6PD status determines the response of cells exposed to nitric oxide (NO) donor. Treatment with NO donor, sodium nitroprusside (SNP), caused apoptosis in G6PD-deficient human foreskin fibroblasts (HFF1), whereas it was growth stimulatory in the normal counterpart (HFF3). Such effects mere abolished by NO scavengers like hemoglobin. Ectopic expression of G6PD in HFF1 cells switched the cellular response to NO from apoptosis to growth stimulation. Experiments with 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one and 8-bromo-cGMP showed that the effects of NO on HFF1 and HFF3 cells were independent of cGMP signalling pathway. Intriguingly, trolox prevented the SNP-induced apoptosis in HFF1 cells. These data demonstrate that G6PD plays a critical role in regulation of cell growth and survival. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved
— id: 54603, year: 2000, vol: 475, page: 257, stat: Journal Article,

MAPK-dependent expression of p21(WAF) and p27(kip1) in PMA-induced differentiation of HL60 cells
Das D; Pintucci G; Stern A
2000 Apr 21;472(1):50-52, FEBS letters
Treatment of HL60 cells with phorbol 12-myristate 13-acetate (PMA) results in growth arrest and differentiation towards the macrophage lineage. PMA-induced changes are easily monitored by morphological changes while cells in suspension start adhering onto substrate. PMA induces rapid activation of the extracellular signal-regulated kinases (ERKs). Activation of the ERK pathway is essential to PMA-induced differentiation of HL60 cells. PMA also induces the expression of the cyclin-dependent kinase inhibitors p21(WAF) and p27(kip1), which is modulated by the use of an inhibitor of the ERK cascade. This implies that a link exists between ERK activation and p21(WAF) and p27(kip1) induction in the process of terminal differentiation
— id: 9009, year: 2000, vol: 472, page: 50, stat: Journal Article,

Differentiation status modulates transcription factor NF-kappa B activity in unstimulated human hepatocellular carcinoma cell lines
Liu, TZ; Hu, CCA; Chen, YH; Stern, A; Cheng, JT
2000 APR 3 ;151(1):49-56, Cancer letters
We report herein a novel finding that under an unstimulated condition, a group of four human hepatocellular carcinoma (HCC) cell lines with varying degrees of differentiation, can spontaneously activate NF-kappa B. The propensity of activation coincided inversely with the differentiation status, with order being SK-Hep-1 > J5 > Hep3B > HepG2. Further studies indicate that this pattern of activation correlates excellently with the descending order of intracellular GSH/GSSG ratios as well as with the ascending order in the ability of these cells to generate hydrogen peroxide. Taken together, our data suggest that differentiation status may play a pivotal role in modulating intracellular thiol redox status and the extent of catalase expression, which may be crucial in the control of NF-kappa B activity in these HCC cells. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved
— id: 54737, year: 2000, vol: 151, page: 49, stat: Journal Article,

Nitric oxide stimulates tyrosine phosphorylation of focal adhesion kinase, Src kinase, and mitogen-activated protein kinases in murine fibroblasts
Monteiro HP; Gruia-Gray J; Peranovich TM; de Oliveira LC; Stern A
2000 Jan 15;28(2):174-182, Free radical biology & medicine
Nitric oxide (NO) can participate in cellular signaling. In this study, monoclonal antibodies against proteins from the growth factor-mediated signalling pathway were used to identify a set of 126-, 56-, 43-, and 40-kDa proteins phosphorylated on tyrosine at NO stimulation of murine fibroblasts overexpressing the human epidermal growth factor receptor. The band corresponding to the 126-kDa protein was FAK. The 56-kDa protein was Src kinase, and the doublet 43- and 40-kDa protein corresponded to the extracellular-regulated MAP kinases (ERK1/ERK2). The effects of NO on focal adhesion complexes were also investigated. FAK was constitutively associated with the adapter protein Grb2 in HER14 cells. Treatment of the cells with the NO donor, sodium nitroprusside, or with EGF did not change this association. We also detected a basal constitutive association of Src kinase with FAK in HER14 cells. In NO-treated cells, this association was stimulated. The doublet 43/40-kDa protein was identical to the ERK1/ERK2 MAP kinases. NO stimulated an increase in ERK1/ERK2 phosphorylation as assessed by a shift in its eletrophoretic mobility and by increased phosphotyrosine immunoreactivity. Furthermore, NO-dependent activation of ERK1/ERK2 depended on the intracellular redox status. Inhibition of glutathione synthesis was necessary to promote activation of the kinases
— id: 27869, year: 2000, vol: 28, page: 174, stat: Journal Article,

LDL stimulated protein tyrosine phosphorylation and protein nitration in rabbit aortic endothelial cells
Fries, DM; Neiva, TJC; Oliveira, LCB; Abdalla, DSP; Stern, A; Monteiro, HP
1999 DEC ;27(4):S75-S75, Free radical biology & medicine
— id: 53795, year: 1999, vol: 27, page: S75, stat: Journal Article,

Clastogenic factors: biomarkers of oxidative stress of potential utility in the clinical chemistry laboratory
Liu TZ; Stern A; Emerit I
1999 Apr-Jun;29(2):134-139, Annals of clinical & laboratory science
— id: 8515, year: 1999, vol: 29, page: 134, stat: Journal Article,

The isoprostanes: Novel prostaglandin-like products of the free radical-catalyzed peroxidation of arachidonic acid
Liu, T; Stern, A; Roberts, LJ; Morrow, JD
1999 Jul-Aug;6(4):226-235, Journal of biomedical science
The isoprostanes (IsoPs) are a unique series of prostaglandin- like compounds formed in vivo from the free radical-catalyzed peroxidation of arachidonic acid. This review summarizes our current knowledge regarding these compounds. Novel aspects of the biochemistry and bioactivity of IsoPs are detailed and methods by which these compounds are analyzed are discussed. A considerable portion of this review deals with the utility of measuring IsoPs as markers of oxidant injury in human diseases particularly in association with risk factors that predispose to atherosclerosis, a condition in which excessive oxidative stress has been causally implicated
— id: 27494, year: 1999, vol: 6, page: 226, stat: Journal Article,

Protruding aortic arch atheromas: risk of stroke during heart surgery with and without aortic arch endarterectomy [see comments]
Stern A; Tunick PA; Culliford AT; Lachmann J; Baumann FG; Kanchuger MS; Marschall K; Shah A; Grossi E; Kronzon I
1999 Oct;138(4 Pt 1):746-752, American heart journal
BACKGROUND: Stroke occurs in 1% to 7% of heart surgery. Aortic arch atherosclerosis is a risk factor for intraoperative stroke, and endarterectomy has been proposed to prevent stroke during heart surgery in patients with arch atheromas. METHODS AND RESULTS: Intraoperative transesophageal echocardiography was performed in 3404 patients undergoing heart surgery between 1990 and 1996. Use of transesophageal echocardiography was unselected and based on equipment availability. Aortic arch atheromas (>/=5 mm, or mobile) were seen in 268 (8%) patients. They were evaluated for intraoperative stroke (confirmed by a neurologist and cerebral infarction on computed tomography or magnetic resonance imaging). Arch endarterectomy was performed in 43 patients as an adjunct to their cardiac procedure in an attempt to prevent intraoperative stroke. The intraoperative stroke rate in all 268 patients with atheromas was high (15.3%). On univariate analysis, age, previous stroke, and arch endarterectomy were significantly associated with intraoperative stroke. On multivariate analysis, age (odds ratio 3.9, P =.01) and arch endarterectomy (odds ratio 3.6, P =.001) were independently predictive of intraoperative stroke. Mortality rate in all 268 patients was high (14.9%). These patients with atheromas also had a long recovery room, intensive care unit, and total hospital length of stay (48 days). CONCLUSIONS: Patients with protruding aortic arch atheromas are at high risk for intraoperative stroke, significant and multiple morbidity, prolonged hospital stay, and death resulting from heart surgery. Aortic arch endarterectomy is strongly associated with intraoperative stroke; its use should be carefully considered in light of these results
— id: 6213, year: 1999, vol: 138, page: 746, stat: Journal Article,

The isoprostanes: unique bioactive products of lipid peroxidation. An overview
Liu TZ; Stern A; Morrow JD
1998 Nov-Dec;5(6):415-420, Journal of biomedical science
The development of a specific, reliable and noninvasive method for measuring oxidative stress in humans is essential for establishing the role of free radicals in human diseases. Currently, accurate techniques to assess oxidant injury in vivo are extremely limited although a number of approaches are being investigated. Of these, the measurement of specific products of nonenzymatic lipid peroxidation, the F2-isoprostanes (F2-IsoPs), appears to be a more accurate marker of oxidative stress in vivo in humans than other available methods. The purpose of this brief review is to acquaint the reader with the IsoPs from a biochemical perspective and to provide information regarding the utility of quantifying these compounds as indicators of oxidant stress
— id: 57196, year: 1998, vol: 5, page: 415, stat: Journal Article,

Transesophageal echocardiography in a case of cardiac compression: was it therapeutic?
Rosenzweig BP; Stern A; Kronzon I
1998 May;11(5):494-496, Journal of the American Society of Echocardiography
Cardiac compression is a potentially life-threatening complication of heart surgery. This syndrome often has atypical manifestations, challenging our ability to make a rapid diagnosis and to institute emergent, life-saving treatment. We recently evaluated one such patient who showed cardiac compression caused by an unusual paracardiac mass. The addition of transesophageal echocardiography to the usual transthoracic study may have played more than just a diagnostic role in this case
— id: 12113, year: 1998, vol: 11, page: 494, stat: Journal Article,

Impaired production of nitric oxide, superoxide, and hydrogen peroxide in glucose 6-phosphate-dehydrogenase-deficient granulocytes
Tsai KJ; Hung IJ; Chow CK; Stern A; Chao SS; Chiu DT
1998 Oct 9;436(3):411-414, FEBS letters
Since the generation of superoxide and hydrogen peroxide by NADPH oxidase and nitric oxide (NO) by NO synthase (NOS) in granulocytes is NADPH-dependent, we investigated the production of NO, superoxide and H2O2 in glucose 6-phosphate dehydrogenase (G6PD)-deficient human granulocytes. Our results showed that upon stimulation with either 5 microg/ml of lipopolysaccharide (LPS) or 10 microM of phorbol 12-myristate 13-acetate (PMA), the production of nitrite in normal granulocytes was elevated, 252 +/- 135% and 239 +/- 72%, respectively, compared to the resting stage. In contrast, G6PD-deficient granulocytes did not produce more nitrite upon stimulation with either LPS or PMA compared to the resting stage. Western blot analysis indicated a normal expression pattern of inducible NOS in G6PD-deficient granulocytes. In addition, the production of H2O2 and superoxide was also significantly impaired in G6PD-deficient granulocytes compared to control cells. These data demonstrate that G6PD deficiency causes an impairment in the production of NO, superoxide and H2O2
— id: 57273, year: 1998, vol: 436, page: 411, stat: Journal Article,

Palladium or platinum exacerbates hydroxyl radical mediated DNA damage
Liu, T Z; Lin, T F; Chiu, D T; Tsai, K J; Stern, A
1997 ;23(1):155-161, Free radical biology & medicine
Strand breakage of supercoiled pBR322 DNA by a Fenton system is increased in the presence of palladium or platinum (Pt) ions. Neither Pd nor Pt ions can substitute for iron in the Fenton system. We have obtained several lines of evidence that Pd and Pt ions in the presence of a Fenton system can augment the production of OH., as monitored by a spectrophotometric method quantifying hydroxylated salicylate or by a fluorometric method quantifying catechol production. Furthermore, the promoting effect of both metal ions on OH. production was substantiated by the identification of multiple hydroxylated products of salicylate [2,3-dihydroxybenzoate (A), 2,5-dihydroxybenzoate (B), and catechol (C)] using HPLC. The concentrations of A, B, and C produced in the control were 4.5, 8.0, and 2.0 microM, respectively; whereas, their respective concentrations increased to 23.6, 42.0 and 10.0 microM with the addition of Pd ions. The observed phenomenon was further confirmed by the identification of HO-DMPO spin adducts using ESR spectroscopy. Taken together, our data suggest that the mechanism of Pd or Pt ion-mediated exacerbation of DNA damage by a Fenton system is due to the promotion of OH. production by these metal ions
— id: 133228, year: 1997, vol: 23, page: 155, stat: Journal Article,

Aortic arch endarterectomy increases the risk of stroke during heart surgery in patients with protruding aortic arch atheromas
Stern, A; Tunick, PA; Culliford, AT; Lachmann, J; Baumann, FG; Kanchuger, MS; Marschall, K; Shah, A; Grossi, EA; Kronzon, I
1997 OCT 21 ;96(8):1024-1024, Circulation
— id: 33437, year: 1997, vol: 96, page: 1024, stat: Journal Article,

The intracellular reducing environment modulates cytoregulation and cytotoxicity by reactive oxygen species
Chiu DT; Monteiro HP; Stern A
1996 Aug;24(3):884-887, Transactions (Biochemical Society (Great Britain))
— id: 7916, year: 1996, vol: 24, page: 884, stat: Journal Article,

Nitric oxide stimulates tyrosine phosphorylation in murine fibroblasts in the absence and presence of epidermal growth factor
Peranovich TM; da Silva AM; Fries DM; Stern A; Monteiro HP
1995 Jan 15;305 ( Pt 2):613-619, Biochemical journal
In the present study, utilizing anti-phosphotyrosine monoclonal antibodies, sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) as sources of NO and murine fibroblasts expressing the human epidermal growth factor (EGF) receptor (HER14 cells), we showed that tyrosine phosphorylation of a set of proteins (126, 56 and 43 kDa) was stimulated when cells were incubated with either SNP or SNAP and abolished by Methylene Blue and oxyhaemoglobin. Inhibition by Methylene Blue suggested an involvement of cyclic GMP in the process, which was evidenced by the effects of 8-bromo cyclic GMP. This analogue of cyclic GMP stimulated tyrosine phosphorylation of the same set of proteins phosphorylated after incubation with the NO source. Tyrosine phosphorylation of the same set of proteins was stimulated when cells were incubated simultaneously with SNP and EGF, showing that NO also potentiates EGF-evoked tyrosine kinase activity in HER14 cells. However, stimulation of the autophosphorylation of the EGF receptor, above the levels obtained for EGF alone, was not observed under those conditions. Additionally, we investigated the effects of NO on EGF-receptor tyrosine phosphatase activities in HER14 cells. Increasing concentrations of NO correlate with a gradual inhibition of these activities in HER14 cells, either in intact cells or in cell lysates. Taken together, these observations suggest that NO modulates tyrosine phosphorylation in HER14 cells
— id: 57537, year: 1995, vol: 305 ( Pt 2), page: 613, stat: Journal Article,

IN-VITRO CYTOTOXICITY OF THE CHLORINATED NAPHTHOQUINONE DICHLONE TO HUMAN ENDOTHELIAL ECV304 CELLS
BABICH, H; MARKENSON, DF; BLAU, L; STERN, A
1994 OCT ;8(5):1075-1081, Toxicology in vitro
The cytotoxicity of the pro-oxidant fungicide dichlone (2,3-dichloro-1, 4-naphthoquinone), to the human endothelial cell line, ECV304, was evaluated. The sensitivity of these cells to dichlone was intermediate between that of human hepatoblastoma HepG2 cells (least sensitive) and that of human GM05757 fibroblasts. The midpoint cytotoxicity values for a 24-hr exposure to dichlone was about 0.02 mM when evaluated with the neutral red, acid phosphatase, and XTT tetrazolium assays. Lactic acid dehydrogenase leakage, after a 4-hr exposure, occurred initially at 0.05 mM dichlone. As with other naphthoquinones, cellular metabolism of dichlone presumably could proceed either by a one- or a two-electron reduction reaction. The enhancement of potency of dichlone towards ECV304 cells pretreated with the glutathione-depleting agents, DL-buthionine-[S,R]-sulfoximine, 1-chloro-2,4-dinitrobenzene, and 1,3-bis(chloraethyl)-1-nitrosourea; the reduction in potency of dichlone to cells pretreated with (-)-2-oxo-4-thiazolidine carboxylic acid; the decrease in intracellular glutathione on exposure to dichlone; the subtle damage to the plasma membrane of dichlone-treated cells (as detected by the leakage of lactate dehydrogenase from these cells); and the lack of potentiation of dichlone toxicity by pretreatment with dicoumarol, are all consistent with the one-electron reduction reaction as the dominant pathway and with the subsequent generation of reactive oxygen molecules. The ECV304 cell line proved to be a useful research tool to study cytotoxic injury to endothelial cells
— id: 52312, year: 1994, vol: 8, page: 1075, stat: Journal Article,

NAPHTHOQUINONE CYTOTOXICITY TO BLUEGILL SUNFISH BF-2 CELLS
BABICH, H; PALACE, MR; BORENFREUND, E; STERN, A
1994 JUL ;27(1):8-13, Archives of environmental contamination & toxicology
Bluegill sunfish BF-2 fibroblasts were used to evaluate the in vitro cytotoxicities of 1,4-naphthoquinone (NQ), 5,8-dihydroxy-1,4-NQ, and 2,3-dichloro-1,4-NQ (dichlone); comparisons were made with previously obtained data on the response of human hepatoma HepG2 cells. For both cell types, the sequence of potency was 5,8-dihydroxy-1,4-NQ > 1,4-NQ > dichlone. Dichlone, and, although to a lesser extent, 1,4-NQ and 5,8-dihydroxy-1-4-NQ, induced endoreduplication in the BF-2 cells; for the HepG2 cells, endoreduplication was induced only with dichlone. Exposures to the three NQs reduced intracellular glutathione levels in both cell types. For the BF-2 and HepG2 cells, pretreatments with buthionine sulfoximine (BSO), a glutathione-depleting agent, potentiated the cytotoxicity of 5,8-hydroxy-1,4-NQ and dichlone; pretreatment with dicoumarol, an inhibitor of DT-diaphorase, had no effect on toxicity of these two NQs. Apparently, for these two quinones the predominant metabolic pathway in both the BF-2 and HepG2 cells involved redox cycling via a one-electron reduction reaction, generating reactive oxygen intermediates that consumed intracellular glutathione. Pretreatment of the BF-2 cells with BSO, but not with dicoumarol, potentiated the toxicity of 1,4-NQ, again indicating that metabolism occurred via one electron reduction. However, for the HepG2 cells, pretreatment with dicoumarol, but not with BSO, potentiated the cytotoxicity of 1,4-NQ. Apparently, in the HepG2, as compared to the BF-2, cells, 1,4-NQ was metabolized by DT-diaphorase in a reaction involving a two electron reduction
— id: 52453, year: 1994, vol: 27, page: 8, stat: Journal Article,

AMONG A RANGE OF TRANSITION-METALS AND LIGANDS VANADIUM-CENTER-DOT-DESFERROXAMINE EXCELS IN ACCELERATING REACTIVITY OF FERROCYTOCHROME-C TOWARD MOLECULAR-OXYGEN
DAVISON, AJ; WU, QZ; MOON, J; STERN, A
1994 MAY-JUN ;72(5-6):169-174, Biochemistry & cell biology
Despite early knowledge of the requirement for metals in the reactions of ferrocytochrome c with oxygen, the relative effectiveness of metals and the factors that modulate effectiveness remain unknown. We have compared the catalytic power of five metals and report the effects of pH and ligand on their effectiveness as catalysts. Catalysis by metal ions was greatest at higher pH, where the rate of aerobic oxidation was lowest. Iron (Fe2+), copper (Cu2+), vanadium(V) (V(V)), manganese (Mn2+), and aluminum (Al3+) were tested in combination with EDTA, ADP, histidine, or desferrioxamine (Des) at pH 2.6, 3.2, and 4.0. At pH 2.6, only vanadium(V) increased the initial rate of the oxidation of ferrocytochrome c (by 6.2-fold). At pH 4.0, however, all the metals markedly stimulated the oxidation of cytochrome c. The order of effectiveness was V(V).Des >> Cu.ADP(2+) > Fe.EDTA(2+) > Mn.Des(2+) > Al.EDTA(3+) (where the stated ligand represents the most stimulating one for a given metal). At pH 3.2 the metal complexes had intermediate effects, with vanadium again being the most effective. The preeminence of vanadium among the metals is novel. Where the heme crevice is closed (pH 4), transition metal ions mediated almost all of the reduction of oxygen, while at the lowest pH (2.6) transition metal ions were largely unnecessary. Vanadium(V) was the most active of the metals at all values of pH and the only metal to accelerate the oxidation of ferrocytochrome c at pH 2.6. Understanding of the range of biological actions of vanadium will not be complete without a knowledge of its redox reactivity within the components of biological systems
— id: 52322, year: 1994, vol: 72, page: 169, stat: Journal Article,

Inhibition of epidermal growth factor-dependent protein tyrosine phosphorylation by phorbol myristate acetate is mediated by protein tyrosine phosphatase activity
Errasfa M; Stern A
1994 Feb 14;339(1-2):7-10, FEBS letters
Incubation of HER14 cells with phorbol myristate acetate (PMA) decreases epidermal growth factor (EGF)-dependent protein tyrosine phosphorylation, except for a 40-kDa MAP kinase II-like protein, whose tyrosine phosphorylation is further enhanced. The inhibitory effect of PMA on EGF-dependent protein tyrosine phosphorylation is reversed if cell are pre-incubated with a combination of Na3VO4 and NaF, two known inhibitors of protein tyrosine phosphatase activity. Protein tyrosine phosphatase activity of cell homogenate was measured on immunopurified EGF receptor, and was found to be enhanced in PMA-treated cells. These data suggest that the inhibitory effect of PMA on EGF-dependent protein tyrosine phosphorylation in HER14 cells may be mediated by protein tyrosine phosphatase activity
— id: 56523, year: 1994, vol: 339, page: 7, stat: Journal Article,

Melittin inhibits epidermal growth factor-induced protein tyrosine phosphorylation: comparison with phorbol myristate acetate and calcium ionophore A23187
Errasfa M; Stern A
1994 Jul 21;1222(3):471-476, Biochimica & biophysica acta
In HER14 cells, epidermal growth factor (EGF) induces tyrosine phosphorylation of several proteins, including its own receptor. The bee venom peptide, melittin, impaired EGF-dependent protein tyrosine phosphorylation in a calcium-dependent manner. The melittin effect was similarly reproduced by calcium ionophore A23187. The effect of melittin and calcium ionophore A23187 on EGF-dependent protein tyrosine phosphorylation was abolished by treatment of cells with the calcium chelator EGTA. Phorbol-myristate acetate (PMA) inhibited EGF-dependent protein tyrosine phosphorylation, and when compared to melittin or calcium ionophore A23187, only PMA potentiated the EGF-induced tyrosine phosphorylation of two proteins immunologically related to mitogen activated protein (MAP) kinases of 40 kDa and 44 kDa molecular mass. Unlike PMA, the effect of melittin and calcium ionophore A23187 on inhibition of EGF-dependent protein tyrosine phosphorylation was lost neither in protein kinase C-depleted cells nor in cells treated with the protein tyrosine phosphatase inhibitors NaF and Na3VO4. Melittin inhibited high affinity binding of EGF to its receptor in intact cells, but this effect was not prevented by EGTA. It is concluded that melittin and calcium ionophore A23187 differ from PMA in their inhibition of EGF-dependent protein tyrosine phosphorylation in vivo, by acting via a Ca(2+)-dependent pathway, that is independent of protein kinase C, protein tyrosine phosphatase activity and high affinity binding of EGF to its receptor
— id: 12945, year: 1994, vol: 1222, page: 471, stat: Journal Article,

Effects of H2O2 on protein tyrosine phosphatase activity in HER14 cells
Sullivan SG; Chiu DT; Errasfa M; Wang JM; Qi JS; Stern A
1994 Mar;16(3):399-403, Free radical biology & medicine
Oxidative stress has been implicated in protein phosphorylation and dephosphorylation in cells. In our current studies, H2O2 was shown to reversibly inhibit protein tyrosine phosphatase (PTPase) activity in HER14 cells. H2O2 (150 mM) resulted in 40% inhibition of PTPase activity by 15 min and recovery from inhibition was nearly complete by 60 min. H2O2-induced inhibition or recovery of PTPase activity was not affected by cycloheximide, a protein synthesis inhibitor. L-Buthionine-[S,R]-sulfoximine (BSO), an inhibitor of glutathione synthesis, had no effect on H2O2-induced inhibition of PTPase activity but retarded the recovery of activity. Epidermal growth factor (EGF) and EGTA, a Ca2+ chelator, did not influence H2O2-induced inhibition or recovery of PTPase activity. These results suggest that at least 40% of fibroblast PTPase activity can be regulated by cellular redox activity
— id: 8196, year: 1994, vol: 16, page: 399, stat: Journal Article,

MEMBRANE-CHANGES ASSOCIATED WITH LYSIS OF RED-BLOOD-CELLS BY HYPOCHLOROUS ACID
VISSERS, MCM; STERN, A; KUYPERS, F; VANDENBERG, J; WINTERBOURN, CC
1994 JUN ;16(6):703-712, Free radical biology & medicine
This study was carried out to investigate HOCl-induced lysis of human erythrocytes. Using reagent HOCl with isolated red cells, we showed that the rate of lysis was dependent on the dose of HOCl per red cell rather than on the concentration df oxidant. The process was inhibited by scavengers such as methionine and taurine, but only if they were present at the time of addition of HOCl. Lysis was preceded by a decrease in cell density, a change in the deformability of the membrane as evidenced by ektacytometry, and an increase in K+-leak. Electron microscopy showed extensive disruption of the membrane. Increasing doses of HOCl caused progressive loss of membrane thiols, but complete thiol oxidation by N-ethylmaleimide did not result in an equivalent rate of lysis. Restoration of oxidised thiols by incubation with glucose did not significantly alter the pattern of lysis. Taken together, these results suggest that thiol oxidation was not responsible for HOCl-mediated lysis. There was evidence of increasing crosslinking of membrane proteins on electrophoresis, only some of which was due to the formation of disulfides. TLC of the membrane lipids indicated that there may be formation of chlorohydrins by reaction of HOCl with the fatty acid double bonds. This reaction results in the formation of a more polar species which, if formed, would be extremely disrupting to the lipid bilayer. The results indicate that HOCl-mediated damage to the membrane proteins or to the lipid bilayer comprises an initial damaging event that sets the cells on a path toward eventual lysis
— id: 52446, year: 1994, vol: 16, page: 703, stat: Journal Article,

COMPARATIVE CYTOTOXICITIES OF SELECTED MINOR DIETARY NON-NUTRIENTS WITH CHEMOPREVENTIVE PROPERTIES
BABICH, H; BORENFREUND, E; STERN, A
1993 SEP 30 ;73(2-3):127-133, Cancer letters
The comparative acute cytotoxicities were determined for a varied spectrum of minor dietary non-nutrients that have been implicated as chemopreventive agents. Cytotoxicity was determined with the neutral red (NR) assay, using BALB/c mouse 3T3 fibroblasts as the bioindicators. Based on midpoint cytotoxicity (NR50) values, the range of cytotoxicity for the different chemicals varied by 1000 times. The sequence of potency was tannic acid, tamoxifen citrate, quercetin, benzyl and phenethyl isothiocyanate > glycyrrhetinic acid > indole-3-carbinol > caffeic acid > phytic acid > vanillin > ellagic acid > D-saccharic acid 1,4-lactone. Vanillin, at slight to moderately toxic concentrations, was the only test agent that induced multinucleation in the 3T3 fibroblasts
— id: 52177, year: 1993, vol: 73, page: 127, stat: Journal Article,

OXIDATIVE STRESS IN FISH CELLS - INVITRO STUDIES
BABICH, H; PALACE, MR; STERN, A
1993 FEB ;24(2):173-178, Archives of environmental contamination & toxicology
Bluegill sunfish BF-2 fibroblasts were used in the neutral red (NR) cytotoxicity assay to discern the toxicities of hydrogen peroxide (H2O2) and paraquat as indicated by their abilities to induce oxidative stress. The toxicity of H2O2 was markedly enhanced in BF-2 cells treated with the glutathione depleting agents, buthionine sulfoximine (BSO), maleic acid, and chlorodinitrobenzene; similar treatments did not sensitize the BF-2 cells to paraquat, a redox cycling xenobiotic. BSO treated BF-2 cells, however, were sensitized to nitrofurantoin, also a redox cycling chemical. Diethyldithiocarbamate, an ihibitor of superoxide dismutase, only weakly enhanced the sensitivity of the BF-2 cells to H2O2 and paraquat. 1, 10-Phenanthroline, a chelator of Fe2+ , reduced the cytotoxicity of H2O2 and paraquat, presumably by preventing hydroxyl radical formation in the Fenton reaction. Quin 2 AM, an intracellular chelator of Ca2+, markedly lessened the toxicity of H2O2, but not of para quat; EGTA, an extracellular chelator of Ca2+, had no effect on the toxicity of H2O2 or paraquat. Apparently, perturbation of intracellular Ca2+ homeostasis is involved in H2O2 toxicity. For comparative purposes, some studies were performed with fathead minnow FHM epithelioid cells, BALB/c mouse 3T3 fibroblasts, and human HepG2 hepatoma cells. The BF-2 fibroblast/NR cytotoxicity red assay was shown to be a suitable model to study oxidative stress in fish
— id: 54394, year: 1993, vol: 24, page: 173, stat: Journal Article,

IN-VITRO CYTOTOXICITIES OF 1,4-NAPHTHOQUINONE AND HYDROXYLATED 1,4-NAPHTHOQUINONES TO REPLICATING CELLS
BABICH, H; STERN, A
1993 SEP-OCT ;13(5):353-358, Journal of applied toxicology
Using the human hepatoma cell line, HepG2, and the BALB/c mouse fibroblast cell line, 3T3, as the bioindicators in the neutral red cytotoxicity assay, the effect of hydroxyl substitution on the toxicity of 1,4-naphthoquinone was studied. The sequence of potency for the quinones was 5,8-dihydroxy-1,4-naphthoquinone > 5-hydroxy-1,4-naphthoquinone > 1,4-naphthoquinone much-greater-than-to 2-hydroxy-1,4-naphthoquinone. Pretreatment of the cells with dicoumarol, an inhibitor of DT-diaphorase, enhanced the cytotoxicity of 1,4-naphthoquinone but not of the hydroxylated naphthoquinones. Pretreatment of the BALB/c cells with buthionine sulfoximine, an inhibitor of glutathione synthesis, enhanced the sensitivity of the cells to all the hydroxylated naphthoquinones but not to 1,4-naphthoquinone. A similar pretreatment of the HepG2 cells with buthionine sulfoximine enhanced the toxicity of the 2-hydroxy- and 5,8-dihydroxy-1,4-naphthoquinones but not of 5-hydroxy-1,4-naphthoquinone or of 1,4-naphthoquinone. Some differences were noted in the responses to the hydroxylated 1,4-naphthoquinones between buthionine sulfoximine-treated replicating cells and buthionine sulfoximine-treated isolated rat hepatocytes, a non-replicating cell in culture. The use of a replicating cell system in studying the mechanisms of the cytotoxicity of quinones may be an important adjunct to studies using the isolated rat hepatocytes, which is the standard model system
— id: 52207, year: 1993, vol: 13, page: 353, stat: Journal Article,

EUGENOL CYTOTOXICITY EVALUATED WITH CONTINUOUS CELL-LINES
BABICH, H; STERN, A; BORENFREUND, E
1993 MAR ;7(2):105-109, Toxicology in vitro
The cytotoxicity of eugenol to replicating cells, as mediated by the intracellular level of glutathione and by metabolic activation, was evaluated with the neutral red (NR) assay. The cytotoxicity of eugenol to human HFF fibroblasts and human HepG2 hepatoma cells was increased somewhat in the presence of a hepatic S-9 microsomal fraction from Aroclor-induced rats or hamsters. Exposure of human HepG2 hepatoma cells to eugenol depleted the level of intracellular glutathione. Cells treated with 1-chloro-2,4-dinitrobenzene (CDNB) or buthionine sulphoximine (BSO), agents that deplete intracellular glutathione, were hypersensitive to eugenol. A 1-hr pretreatment with CDNB enhanced the cytotoxicity of eugenol, as did a 24-hr pretreatment with BSO. Intracellular glutathione levels were, apparently, significant in mediating the toxicity of eugenol
— id: 54312, year: 1993, vol: 7, page: 105, stat: Journal Article,

IN-VITRO CYTOTOXICITY OF 1,4-NAPHTHOQUINONE DERIVATIVES TO REPLICATING CELLS
BABICH, H; STERN, A; MUNDAY, R
1993 JUL ;69(1):69-75, Toxicology letters
The acute cytotoxicities of a series of alkyl-1,4-naphthoquinones (NQ) and of 2-hydroxy-3-alkyl-1,4-NQs, as well as some amino derivatives, were evaluated with the neutral red cytotoxicity assay, using BALB/c mouse 3T3 fibroblasts. As compared to the unsubstituted 1,4-
— id: 52252, year: 1993, vol: 69, page: 69, stat: Journal Article,

Inhibition of protein tyrosine phosphatase activity in HER14 cells by melittin and Ca2+ ionophore A23187
Errasfa M; Stern A
1993 Sep 15;247(1):73-80, European journal of pharmacology
We investigated the effect of melittin and Ca2+ ionophore A23187 on protein tyrosine phosphatase activity in HER14 cells (NIH-3T3 cells transfected with human epidermal growth factor 'EGF' receptor). Cell fractions were used to measure protein tyrosine phosphatase activity in vitro using 32P-labeled poly(Glu/Tyr) (4:1) peptide as a substrate. Treatment of HER14 cells with melittin or with A23187, inhibited protein tyrosine phosphatase activity in the cell sonicate and homogenate, as well as in cytosolic and particulate fractions of these cells. The inhibitory effect of both drugs was prevented by preincubating cells with EGTA (ethyleneglycolbis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid). The cyclooxygenase inhibitor indomethacin enhanced the inhibitory effect of A23187, but not that of melittin. Addition of arachidonic acid to the cells partially prevented the inhibition of protein tyrosine phosphatase activity by melittin or A23187. Preexposure of cells to EGF enhanced the inhibitory effect of melittin--but not that of A23187. Addition of CaCl2, or MgCl2 to the cell homogenate inhibited protein tyrosine phosphatase activity. These results show that protein tyrosine phosphatase activity in HER14 cells is inhibited by melittin and Ca2+ ionophore A23187 through a Ca(2+)-dependent mechanism, and is regulated by arachidonic acid metabolism and EGF receptor activation
— id: 6367, year: 1993, vol: 247, page: 73, stat: Journal Article,

INHIBITION OF PROTEIN TYROSINE PHOSPHATASE-ACTIVITY IN HER14 CELLS BY MELITTIN AND CALCIUM IONOPHORE A23187
ERRASFA, M; STERN, A
1993 JAN 9 ;53(5):309-309, Journal of cellular biochemistry
— id: 54366, year: 1993, vol: 53, page: 309, stat: Journal Article,

Ascorbic acid inhibits protein tyrosine phosphatases in NIH 3T3 cells expressing human epidermal growth factor receptors
Monteiro HP; Ivaschenko Y; Fischer R; Stern A
1993 Dec;25(12):1859-1864, International journal of biochemistry
1. Physiological concentrations of ascorbic acid inhibited PTPase activity in HER 14 cells. 2. Higher concentrations of ascorbic acid produced a weaker inhibitory effect on PTPase activity in HER 14 cells. 3. EGF prevented the inhibitory effect of ascorbic acid on PTPase activity in HER 14 cells. 4. The inhibitory effect of physiological concentrations of ascorbic acid on PTPase activity depends on density of the cell culture, with less dense populations exhibiting greater inhibition of PTPase activity. 5. These observations suggest that ascorbic acid might have a modulatory role in cellular phosphorylation-dephosphorylation events
— id: 8392, year: 1993, vol: 25, page: 1859, stat: Journal Article,

Vanadium as a modulator of cellular regulatory cascades and oncogene expression
Stern A; Yin X; Tsang SS; Davison A; Moon J
1993 Mar-Apr;71(3-4):103-112, Biochemistry & cell biology
Vanadium, a trace metal in the environment and in biological systems, influences the behavior of enzymes, mimics and regulates growth factor activity, is a potential mutagenic and carcinogenic agent, and regulates gene expression. The diverse biological actions of vanadium result from its capacity to function as an oxyanion, oxycation, or prooxidant. Vanadium is found in water, rocks, and soils in low concentration and in relatively high concentrations in coal and oil deposits. Vanadium compounds at much higher concentrations than are typically ingested are being considered in the treatment of diabetes mellitus. The actions of insulin and vanadium on the insulin receptor are similar, but the mechanisms are not identical. Vanadium modulates growth-factor-mediated signal transduction pathways. Vanadium promotes cell transformation and diminishes cell adhesion. Consistent with its mitogenic action and its capacity to mimic mitogenic growth factors, vanadium stimulates expression of protooncogenes. In particular, oxygen-derived active species are involved in the expression of the jun protooncogene in the presence of vanadium. The unique cellular activity of vanadium makes it a tool of unparalleled potential for studying mechanisms of cell growth, differentiation, and metabolism
— id: 56593, year: 1993, vol: 71, page: 103, stat: Journal Article,

INVITRO CYTOTOXICITY OF METHYLATED PHENYLENEDIAMINES
BABICH, H; STERN, A; MUNDAY, R
1992 NOV ;63(2):171-179, Toxicology letters
The acute cytotoxicities of methylated phenylenediamines (PDs) were evaluated with the neutral red assay, using BALB/c 3T3 mouse fibroblasts as the bioindicators. When the test agents were grouped according to their degree of methylation, good correlations were noted between their in vitro cytotoxicity and their in vivo myotoxicity to experimental animals, as well as to their in vitro autoxidation rates. For test agents of comparable methylation, the sequence of potency was ring-methylated p-PD > N-methylated p-PD >> N-methylated o-PD > N-methylated m-PD
— id: 51806, year: 1992, vol: 63, page: 171, stat: Journal Article,

Desferrioxamine enhances the reactivity of vanadium (IV) and vanadium (V) toward ferri- and ferrocytochrome c
Stern A; Davison AJ; Wu Q; Moon J
1992 ;12(5):373-380, Free radical biology & medicine
Ligands, especially desferrioxamine, affect the rate at which vanadium reduces or oxidizes cytochrome c. Whether reduction or oxidation occurs, and how fast, depends on the nature of the ligand, the state of reduction of the vanadium, the pH (6.0, 7.0, or 7.4), and the availability of oxygen. In general, oxidation of ferrocytochrome c was favored by (1) low pH, (2) an oxidized state of the vanadium, (3) the presence of oxygen, and (4) more strongly binding ligands (desferrioxamine much greater than histidine = ATP greater than EDTA greater than albumin greater than aquo). Thus, at pH 6.0, desferrioxamine accelerated the V(V)-catalyzed ferrocytochrome c oxidation 160-fold aerobically, and 3500-fold anaerobically. In general, strongly binding ligands slowed oxidations, especially at higher pH. Desferrioxamine was unique among the five ligands in that it not only accelerated oxidation of ferrocytochrome c at pH 6.0, but at pH 7.4 the redox balance shifted to the point where it paradoxically reduced ferricytochrome c. V(V) is an improbable electron donor, but desferrioxamine will reduce cytochrome c, and V(V) accelerates this process. Oxidation of cytochrome c by V(V):desferrioxamine was faster anaerobically, and reduction by V(IV):desferrioxamine was faster aerobically. Although V(V) did not oxidize ferrocytochrome c at pH 7.4, V(IV) did, provided oxygen and desferrioxamine were both present. V(IV):desferrioxamine almost completely reduced ferricytochrome c, and this reduction was followed by a slow, progressive oxidation. This latter oxidation of cytochrome c is mediated by active species generated in the reaction between V(IV):desferrioxamine and oxygen, because none of these reagents alone can induce oxidation at a comparable rate. The mediating species were transient, and generated in reactions with oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)
— id: 13798, year: 1992, vol: 12, page: 373, stat: Journal Article,

EFFECTS OF LIGANDS ON REDUCTION OF OXYGEN BY VANADIUM(IV) AND VANADIUM(III)
STERN, A; DAVISON, AJ; WU, QZ; MOON, J
1992 NOV 15 ;299(1):125-128, Archives of biochemistry & biophysics. ABB
— id: 51827, year: 1992, vol: 299, page: 125, stat: Journal Article,

Inhibition of hemin-induced hemolysis by desferrioxamine: binding of hemin to red cell membranes and the effects of alteration of membrane sulfhydryl groups
Sullivan SG; Baysal E; Stern A
1992 Feb 17;1104(1):38-44, Biochimica & biophysica acta
Hemin binds to red cell membranes during hemin-induced hemolysis but the precise mechanism of hemolysis has not been characterized. Desferrioxamine (DFO), an iron chelator, inhibited hemin-induced hemolysis. DFO partially prevented hemin binding to red cell membranes and partially removed previously bound hemin. Glutathione, an intracellular sulfhydryl compound, also inhibited hemin-induced hemolysis but was only about one tenth as potent as DFO. Decrease of membrane sulfhydryl groups by treatment of cells with either N-ethylmaleimide (NEM) or diamide (azodicarboxylic acid bis [dimethylamide]) enhanced hemin-induced hemolysis. Enhancement of hemin-induced hemolysis by NEM and diamide and inhibition of hemolysis by DFO were independent with no evidence of synergism or interference between the two processes. Red cell membranes were saturated with hemin at approximately 75 nmol per mg protein. DFO decreased the hemin saturation level to 25 nmol per mg protein. In the presence of DFO, hemin was bound as the DFO-hemin complex since membranes preferentially removed DFO-hemin complexes from mixtures of complexed and free hemin while free DFO was not bound by the membranes. Access to the inner surface of the membrane was required for binding of the DFO-hemin complex since DFO completely prevented hemin binding in intact cells but not in cells undergoing hemolysis or red cell ghosts. Approximately 50 x 10(6) molecules of hemin were bound to the membrane of one red cell following hemin-induced hemolysis
— id: 13690, year: 1992, vol: 1104, page: 38, stat: Journal Article,

Inhibition of protein tyrosine phosphatase activity by diamide is reversed by epidermal growth factor in fibroblasts
Monteiro HP; Ivaschenko Y; Fischer R; Stern A
1991 Dec 16;295(1-3):146-148, FEBS letters
Diamide (azodicarboxylic acid bis(dimethylamide] inhibits protein tyrosine phosphatase activity in fibroblasts without altering protein tyrosine kinase activity associated with the epidermal growth factor receptor. The loss of protein tyrosine phosphatase activity caused by diamide is reversed by 2-mercaptoethanol or epidermal growth factor
— id: 8391, year: 1991, vol: 295, page: 146, stat: Journal Article,

TETRAVALENT VANADIUM RELEASES FERRITIN IRON WHICH STIMULATES VANADIUM-DEPENDENT LIPID-PEROXIDATION
Monteiro, HP; Winterbourn, CC; Stern, A
1991 May 15;12-3(10):125-129, Free radical research communications
— id: 32183, year: 1991, vol: 12-3, page: 125, stat: Journal Article,

OXIDATION OF NADH BY VANADIUM - KINETICS, EFFECTS OF LIGANDS AND ROLE OF H2O2 OR O2
Stankiewicz, PJ; Stern, A; Davison, AJ
1991 May 15;287(1):8-17, Archives of biochemistry & biophysics. ABB
— id: 32184, year: 1991, vol: 287, page: 8, stat: Journal Article,

Red cell-neutrophil interactions in the regulation of active oxygen species and lipoxygenase products
Stern A
1991 ;314:103-107, Advances in experimental medicine & biology
— id: 14234, year: 1991, vol: 314, page: 103, stat: Journal Article,

Desferrioxamine protects human red blood cells from hemin-induced hemolysis
Baysal, E; Monteiro, H P; Sullivan, S G; Stern, A
1990 ;9(1):5-10, Free radical biology & medicine
Hemin binding to red cell membranes, its effect on red cell hemolysis, and it interaction with desferrioxamine (DFO) in these processes were investigated. DFO interacted with hemin via the iron moiety. Blockage of the binding groups in DFO prevented interaction of DFO with hemin, implying the importance of the hydroxamic acid groups in DFO-hemin interactions. Since hemolysis is a result of hemin association with the membrane components, its binding in the presence and absence of DFO was studied. DFO strongly inhibited hemin-induced lysis in a concentration-dependent manner. With 50 microM hemin, 1 mM DFO completely inhibited lysis. Preincubation of ghost membranes with DFO (1 mM) inhibited binding of hemin (50 microM) to membranes by 42%. After ghost membranes were preincubated with hemin (50 microM), the addition of DFO (1 mM) removed 20% of the membrane-bound hemin. It is suggested that DFO may have an important role in alleviating the hemin-induced deleterious effects on the red cell membrane, especially in hemolytic anemias associated with unstable, autoxidized hemoglobins
— id: 148882, year: 1990, vol: 9, page: 5, stat: Journal Article,

TETRAVALENT VANADIUM MEDIATED OXIDATION OF LOW-DENSITY- LIPOPROTEIN
Dickson, C; Stern, A
1990 May;22(5):501-50?, International journal of biochemistry
— id: 31880, year: 1990, vol: 22, page: 501, stat: Journal Article,

Effects of 1,4-naphthoquinone derivatives on red blood cell metabolism
Kruger-Zeitzer, E; Sullivan, S G; Stern, A; Munday, R
1990 Apr;10(2):129-133, Journal of applied toxicology
The effect on red blood cell metabolism of a series of substituted 1,4-naphthoquinones has been investigated. 2-Methoxy-1,4-naphthoquinone was found to be a potent oxidative compound, generating hydrogen peroxide in erythrocytes and causing both methemoglobin formation and glutathione depletion in the absence of glucose. Flux of glucose through both glycolysis and the hexose monophosphate shunt was stimulated. 2-Hydroxy- and 2,3-dihydroxy-1,4-naphthoquinone were less oxidative. Both compounds caused oxidation of glutathione and formation of hydrogen peroxide with corresponding stimulation of the hexose monophosphate shunt, but did not cause methemoglobin formation. 2-Hydroxy-3-alkyl-1,4-naphthoquinones were not oxidative but did increase the flux of glucose through glycolysis, possibly reflecting membranal damage. The in vitro oxidative effects of these substances do not correlate with their hemolytic activity in rats, indicating that factors other than oxidative damage are important in mediating the in vivo toxicity of these substances
— id: 148881, year: 1990, vol: 10, page: 129, stat: Journal Article,

Toxicity of aromatic thiols in the human red blood cell
Amrolia P; Sullivan SG; Stern A; Munday R
1989 Apr;9(2):113-118, Journal of applied toxicology
Thiophenol and 4-aminothiophenol were used to study levels of toxicity in human red blood cells. Thiophenols caused conversion of oxyhemoglobin to methemoglobin. Reduction of corresponding disulfides by intracellular glutathione caused cyclic reduction/oxidation reactions, resulting in increased oxidative flux. Three levels of oxidative stress were observed in these experiments: the lowest level resulted from incubation with 0.25 mM thiophenol; the intermediate level with 0.50 mM thiophenol or 0.25 mM 4-aminothiophenol; the highest levels with 0.50 mM 4-aminothiophenol. Methemoglobin formation increased with increasing level of oxidative stress. Glycolysis and the hexose monophosphate shunt were inhibited at the intermediate and highest levels of stress, respectively. Above the highest level of stress non-intact hemoglobin was formed and cell lysis occurred. These metabolic responses were reflected in cellular levels of NADH, NADPH and reduced glutathione. At the lowest level of oxidative stress, both glycolysis and hexose monophosphate shunt were increased such that near-normal levels of NADH, NADPH and reduced glutathione were maintained and methemoglobin formation was kept to a minimum. The response of red cells to 0.25 mM thiophenol appears to represent a level of oxidative stress to which the cell is capable of adaptive metabolic response. Glycolysis contributes approximately one-quarter of the total reducing equivalents from glucose metabolism in response to the oxidative challenge by thiophenol. The results suggest that the metabolic response to autoxidation of endogenous thiols is thiol exchange with glutathione and reduction of resulting glutathione disulfide by the hexose monophosphate shunt
— id: 10676, year: 1989, vol: 9, page: 113, stat: Journal Article,

EFFECT OF OXIDATIVE STRESS ON MEMBRANE PHOSPHOLIPID AND PROTEIN ORGANIZATION IN HUMAN-ERYTHROCYTES
Arduini, A; Stern, A; Storto, S; Belfiglio, M; Mancinelli, G; Scurti, R; Federici, G
1989 Aug 15;273(1):112-120, Archives of biochemistry & biophysics. ABB
— id: 31768, year: 1989, vol: 273, page: 112, stat: Journal Article,

Binding of iron to human red blood cell membranes
Baysal E; Sullivan SG; Stern A
1989 ;8(1):55-59, Free radical research communications
The binding of Fe3+ to red cell membranes was studied in a system in which lipid peroxidation was proportional to Fe3+ concentration. Binding of Fe3+ was evaluated by labeling with 59FeCl3 and measurement of NMR water-proton relaxation times. Labeling with 59Fe showed that 95% of the Fe3+ was membrane bound at 100 microM FeCl3 in a 1.5 mg protein/ml membrane suspension. Both spin-lattice (T1) and spin-spin (T2) relaxation times decreased with increasing Fe3+ concentration. Addition of red cell membrane suspensions largely prevents the Fe3+ effect on relaxation times. Charge transfer to Fe3+ may occur at the membrane binding site with resultant decrease in the Fe3+ effect on water-proton relaxation times. These studies support the hypothesis that Fe3+ binds to the membrane and generates free radicals at the binding site
— id: 10818, year: 1989, vol: 8, page: 55, stat: Journal Article,

Prooxidant and antioxidant effects of ascorbate on tBuOOH-induced erythrocyte membrane damage
Baysal E; Sullivan SG; Stern A
1989 ;21(10):1109-1113, International journal of biochemistry
1. t-Butylhydroperoxide (tBuOOH) a lipoperoxide analog, causes rapid and considerable sulphydryl (SH) oxidation but almost no lipid peroxidation in red blood cell membranes (ghosts) containing no detectable haemoglobin. 2. tBuOOH, in the presence of ascorbate, produces significant lipid peroxidation the level of which is proportional to the ascorbate concentration. The initiation of lipid peroxidation is thought to occur by the reactive tBuO (butoxyl) species via the reductive decomposition of tBuOOH by ascorbate. 3. Ascorbate protects ghost membranes from the tBuOOH-induced SH oxidation in a dose-dependent fashion. 4. There is no parallelism between lipid peroxidation and SH oxidation in these systems. This suggests that the two processes occur independently of each other. 5. These findings indicate that, simultaneously, ascorbate can have both a protective and a prooxidant action in different membrane components under the same oxidative stress
— id: 10819, year: 1989, vol: 21, page: 1109, stat: Journal Article,

Glucose metabolism and hemoglobin reactivity in human red blood cells exposed to the tryptophan metabolites 3-hydroxyanthranilate, quinolinate and picolinate
Dykens JA; Sullivan SG; Stern A
1989 May 15;38(10):1555-1562, Biochemical pharmacology
Glucose metabolism and hemoglobin reactivity in intact human erythrocytes were assessed in the presence of the tryptophan metabolites, 3-hydroxyanthranilate (3-HAT), quinolinate and picolinate. Of these compounds, only 3-HAT altered red cell oxidative status by inducing, in a dose-dependent manner, formation of methemoglobin and non-functional oxidation products of hemoglobin, and by increasing both net glycolytic flux and flux through the hexose monophosphate shunt. 3-HAT also decreased the normal lactate to pyruvate production ratio with pyruvate accumulating at the expense of lactate. These findings are consistent with the auto-oxidative reactivity of quinolinate, picolinate, and 3-HAT in that only 3-HAT undergoes base-catalyzed auto-oxidation (Dykens et al., Biochem Pharmacol 36: 211-217, 1987). Lactate and pyruvate added to the medium in physiologic concentrations uncoupled oxidative glycolysis from reductive glycolysis, resulting in accumulation of pyruvate in the presence of 3-HAT with little increase in total glycolytic flux. Superoxide dismutase (SOD), which accelerates 3-HAT auto-oxidation in vitro (Dykens et al., Biochem Pharmacol 36: 211-217, 1987), exacerbated HAT-mediated oxidative insult by increasing methemoglobin formation, hexose monophosphate shunt flux, and pyruvate accumulation. Persistence of 3-HAT-induced red cell metabolic responses and oxidative damage in the presence of SOD, DETAPAC (diethylenetriaminepentaacetic acid) and formate suggests that an organic-based radical, perhaps the anthranilyl radical produced during 3-HAT auto-oxidation, is the proximate agent exerting oxidative stress. Slow rates of auto-oxidation indicate that 3-HAT may be useful as a probe of antioxidant mechanisms in normal and diseased red blood cells
— id: 10619, year: 1989, vol: 38, page: 1555, stat: Journal Article,

Drug-induced oxidative denaturation in red blood cells
Stern A
1989 Oct;26(4):301-306, Seminars in hematology
— id: 10472, year: 1989, vol: 26, page: 301, stat: Journal Article,

Human red cells enhance the formation of 5-lipoxygenase-derived products by neutrophils
Stern A; Serhan CN
1989 ;7(3-6):335-339, Free radical research communications
Upon activation, human neutrophils generate 5-lipoxygenase products which are involved in inflammation as well as other physiological and pathophysiological processes. We have examined the influence of red cells on the generation of lipoxygenase-derived products by neutrophils utilizing high pressure liquid chromatography system which permitted quantitation of 5-HETE, leukotriene B4 (and its isomers) and the omega oxidation products of leukotriene B4 (20-hydroxyleukotriene B4, 20-carboxyleukotriene B4) within the same sample. Co-incubation of red cells with neutrophils (50:1, red cells:neutrophils) resulted in a 722 percent increase in 5-hydroxyeicosatetraenoic acid production and a slight increase in leukotriene B4 and its omega oxidation products which were not accompanied by increases in 15-hydroxyeicosatetraenoic acid production. The role of the sulfhydryl status of the red cell and its ability to scavenge hydrogen peroxide were assessed in relationship to the interaction of red cells on the neutrophil-derived lipoxygenase products. Together, these findings indicate that red cells can regulate the levels of lipid-derived mediators produced by neutrophils. Moreover, they suggest that red cell-neutrophil interactions may be of importance in inflammatory reactions
— id: 10829, year: 1989, vol: 7, page: 335, stat: Journal Article,

Vanadate-mediated oxidation of NADH: description of an in vitro system requiring ascorbate and phosphate
Yoshino S; Sullivan SG; Stern A
1989 Jul;272(1):76-80, Archives of biochemistry & biophysics. ABB
Oxidation of NADH has been observed in an in vitro system requiring NADH, vanadate, ascorbate, and phosphate. Similar results were observed with NADPH. Ascorbate provides the reducing equivalents necessary to reduce vanadate to vanadyl. Vanadyl autoxidizes producing superoxide which initiates a free radical chain reaction resulting in oxidation of NADH. Oxidation is inhibited by superoxide dismutase but not by catalase or ethanol. Ascorbate functions to initiate the free radical chain reaction but is not required in stoichiometric concentrations. At higher concentrations, ascorbate inhibits NADH oxidation. Inorganic phosphate was required for NADH oxidation. Dialysis of phosphate buffers against solutions containing apoferritin or conalbumin or addition of transition metal cations or chelators to the reaction medium did not alter dependence on phosphate. Phosphate and vanadate were interchangeable in their effects on kinetic parameters of NADH oxidation except that vanadate was 100 times more potent than phosphate. Vanadate participates directly in the initiating and propagating redox reactions of NADH oxidation. Phosphate may be important in lowering the energy of activation for the necessary transfer of hydronium ion and water in the transition state between vanadate anion and vanadyl cation
— id: 10557, year: 1989, vol: 272, page: 76, stat: Journal Article,

Influence of exogenous iron and ascorbate on H2O2-induced glutathione oxidation in red cells
Baysal E; Sullivan SG; Stern A
1988 Aug;17(2):211-215, Biochemistry international
The effective fall in cytosolic reduced glutathione levels in intact red cells exposed to exogenous oxidant stress in the form of Fe2+, H2O2 and ascorbate was caused by H2O2 alone. Relatively high concentrations of Fe2+ had no contributory effect on the oxidizing capacity of H2O2. Ascorbate, at physiological levels, showed no protection whereas glucose was totally protective. Since glucose, via hexose monophosphate shunt, is the only source of reducing equivalent in red cells, the NADPH/NADP+ redox role in the diminution of intracellular reduced glutathione
— id: 11008, year: 1988, vol: 17, page: 211, stat: Journal Article,

Screening devices for diminished cognitive capacity
Strain, J J; Fulop, G; Lebovits, A; Ginsberg, B; Robinson, M; Stern, A; Charap, P; Gany, F
1988 Jan;10(1):16-23, General hospital psychiatry
This study compares three commonly used tests to detect organic mental disorders: the Mini-Mental State (MMS), Cognitive Capacity Screening Examination (CCSE), and Tachistoscope (T-Scope). Ninety-seven medical-surgical inpatients at the Mount Sinai Hospital referred for psychiatric consultation had a Missouri Mental Status Examination performed by a psychiatrist who also rated the patients' organic mental disorder as 'none,' 'mild,' 'moderate,' or 'severe.' The CCSE, MMS, and T-Scope, respectively, showed: sensitivity--0.54, 0.52, 0.68; specificity--0.85, 0.76, 0.79; and positive predictive value--0.83, 0.74, 0.79. False negatives occurred more often among those patients with mild organic mental disorders with all instruments (p = 0.05), while the T-Scope could not be administered in 27% of the patients. Screening instruments with increased acceptability, sensitivity, and specificity need to be developed to identify a potentially life-threatening disorder
— id: 97804, year: 1988, vol: 10, page: 16, stat: Journal Article,

NMR water-proton spin-lattice relaxation time of human red blood cells and red blood cell suspensions
Sullivan, S G; Stern, A; Rosenthal, J S; Minkoff, L A; Winston, A
1988 Jul 18;234(2):349-352, FEBS letters
NMR water-proton spin-lattice relaxation times were studied as probes of water structure in human red blood cells and red blood cell suspensions. Normal saline had a relaxation time of about 3000 ms while packed red blood cells had a relaxation time of about 500 ms. The relaxation time of a red cell suspension at 50% hematocrit was about 750 ms showing that surface charges and polar groups of the red cell membrane effectively structure extracellular water. Incubation of red cells in hypotonic saline increases relaxation time whereas hypertonic saline decreases relaxation time. Relaxation times varied independently of mean corpuscular volume and mean corpuscular hemoglobin concentration in a sample population. Studies with lysates and resealed membrane ghosts show that hemoglobin is very effective in lowering water-proton relaxation time whereas resealed membrane ghosts in the absence of hemoglobin are less effective than intact red cells
— id: 148883, year: 1988, vol: 234, page: 349, stat: Journal Article,

Oxidative reactivity of the tryptophan metabolites 3-hydroxyanthranilate, cinnabarinate, quinolinate and picolinate
Dykens, J A; Sullivan, S G; Stern, A
1987 Jan 15;36(2):211-217, Biochemical pharmacology
The oxidative reactivities of four tryptophan metabolites in the kynurenine pathway were examined as a potential mechanism for their reported neurotoxicities and carcinogenicities. Neither quinolinic acid, a neurotoxin, nor its monocarboxylic analogue, picolinic acid, auto-oxidized over a wide pH range. However, 3-hydroxyanthranilic acid (3-HAT), a carcinogen, readily auto-oxidized and the reaction rate increased exponentially with increasing pH. 3-HAT auto-oxidation likely involves two steps: auto-oxidation of 3-HAT to the semiquinoneimine (anthranilyl radical) which oxidizes to the quinoneimine, followed by condensation and oxidation reactions to yield a second carcinogen, cinnabarinic acid. 3-HAT auto-oxidation to cinnabarinate required molecular oxygen and generated superoxide radicals and H2O2. Superoxide dismutase (SOD) accelerated 3-HAT auto-oxidation 4-fold, probably by preventing back reactions between superoxide and either the anthranilyl radical or the quinoneimine formed during the initial step of auto-oxidation. Catalase did not accelerate 3-HAT auto-oxidation, but it did prevent destruction of cinnabarinate by H2O2. Interconversion between oxyhemoglobin and methemoglobin occurred during 3-HAT auto-oxidation, although neither form of hemoglobin altered rates of 3-HAT auto-oxidation. Mn2+, Mn3+ and Fe3+-EDTA did not directly catalyze cinnabarinate formation in the absence of O2, but they did accelerate cinnabarinate formation under aerobic conditions
— id: 148884, year: 1987, vol: 36, page: 211, stat: Journal Article,

MECHANISM OF KAINATE TOXICITY TO CEREBELLAR NEURONS INVITRO IS ANALOGOUS TO REPERFUSION TISSUE-INJURY
DYKENS, JA; STERN, A; TRENKNER, E
1987 OCT ;49(4):1222-1228, Journal of neurochemistry
— id: 41674, year: 1987, vol: 49, page: 1222, stat: Journal Article,

FLUORESCENT PROPERTIES OF MEROCYANINE-540 IN SOLUTIONS OF SIALOGANGLIOSIDES
GUARCELLO, V; STERN, A; RIZZA, V
1987 FEB 14 ;917(2):318-323, Biochimica & biophysica acta
— id: 41737, year: 1987, vol: 917, page: 318, stat: Journal Article,

HUMAN RED-CELLS SCAVENGE EXTRACELLULAR HYDROGEN-PEROXIDE AND INHIBIT FORMATION OF HYPOCHLOROUS ACID AND HYDROXYL RADICAL
WINTERBOURN, CC; STERN, A
1987 NOV ;80(5):1486-1491, Journal of clinical investigation
— id: 41667, year: 1987, vol: 80, page: 1486, stat: Journal Article,

PHENYLHYDRAZINE-INDUCED CHANGES IN ERYTHROCYTE-MEMBRANE SURFACE LIPID PACKING
ARDUINI, A; CHEN, Z; STERN, A
1986 NOV 6 ;862(1):65-71, Biochimica & biophysica acta
— id: 41541, year: 1986, vol: 862, page: 65, stat: Journal Article,

SPECTRIN DEGRADATION IN INTACT RED-BLOOD-CELLS BY PHENYLHYDRAZINE
ARDUINI, A; STERN, A
1985 DEC 15 ;34(24):4283-4289, Biochemical pharmacology
— id: 41310, year: 1985, vol: 34, page: 4283, stat: Journal Article,

Comparative oxidative damage in red cells and myelin
Arduini, A; Sullivan, S G; Stern, A
1985 ;195:123-133, Progress in clinical & biological research
— id: 148885, year: 1985, vol: 195, page: 123, stat: Journal Article,

PLASMODIUM-FALCIPARUM INVITRO - DIMINISHED GROWTH IN HEMOGLOBIN-H DISEASE ERYTHROCYTES
IFEDIBA, TC; STERN, A; IBRAHIM, A; RIEDER, RF
1985 ;65(2):452-455, Blood
— id: 41258, year: 1985, vol: 65, page: 452, stat: Journal Article,

The effect of nitrone spin trapping agents on red cell glucose metabolism
Thornalley PJ; Stern A
1985 ;1(2):111-117, Free radical research communications
The nitrone spin trapping agents, 5,5-dimethyl-1-pyrroline-N-oxide and N-t-butyl-alpha-phenyl-nitrone, affect the metabolism of glucose by red cells. Both nitrone spin trapping agents have a dose-dependent inhibitory effect on the metabolism of glucose via the hexose monophosphate pathway. The formation of lactate and pyruvate via the Embden-Meyerhoff pathway in red cells is not significantly affected by treatment with 5,5-dimethyl-1-pyrroline-N-oxide, whereas, treatment with N-t-butyl-alpha-phenylnitrone supresses pyruvate and stimulates lactate formation. These results suggest that nitrone spin trapping agents inhibit the hexose monophosphate pathway in red cells. Since the stimulation of the flux of glucose oxidised via this pathway is thought to be important in the ability of red cells to respond to oxidative stress, the treatment of red cells with spin trapping agents appears to inhibit the cellular protective (antioxidant) response. The use of nitrone spin trapping agents in the study of red cells under oxidative stress (imposed by the spontaneous autoxidation of metabolites or by drug-induced processes) is predicted to exaggerate the degree of oxidative damage by virtue of the inhibitory effort of nitrone spin traps on the hexose monophosphate shunt
— id: 11451, year: 1985, vol: 1, page: 111, stat: Journal Article,

RED BLOOD-CELL OXIDATIVE-METABOLISM INDUCED BY HYDROXYPYRUVALDEHYDE
THORNALLEY, PJ; STERN, A
1985 ;34(8):1157-1164, Biochemical pharmacology
— id: 41231, year: 1985, vol: 34, page: 1157, stat: Journal Article,

THE HYDROLYTIC AUTOXIDATION OF 1,4-NAPHTHOQUINONE-2-POTASSIUM SULFONATE - IMPLICATIONS FOR 1,4-NAPHTHOQUINONE-2-POTASSIUM SULFONATE-INDUCED OXIDATIVE STRESS IN THE RED-BLOOD-CELL
THORNALLEY, PJ; STERN, A
1985 DEC ;56(1):55-71, Chemico-biological interactions
— id: 41626, year: 1985, vol: 56, page: 55, stat: Journal Article,

UNIVERSITY-INDUSTRY RELATIONSHIPS
STERN, A
1984 ;4(48):72-72, Science, technology, & human values
— id: 40924, year: 1984, vol: 4, page: 72, stat: Journal Article,

Glucose metabolism of oxidatively stressed human red blood cells incubated in plasma or medium containing physiologic concentrations of lactate, pyruvate and ascorbate
Sullivan, S G; Stern, A
1984 May 1;33(9):1417-1421, Biochemical pharmacology
Red cells suspended in either defined medium or buffered plasma were oxidatively stressed by incubation in the presence of 1,4-naphthoquinone-2-sulfonate at concentrations which caused less than 50% methemoglobin accumulation, stimulation of the hexose monophosphate shunt to less than 15% of capacity, and about a 30% increase in flux through glycolysis. Normal plasma concentrations of lactate and pyruvate in either defined medium or buffered plasma allowed increased contribution of reducing equivalents from glycolysis in response to oxidative stress. Increased utilization of reducing equivalents by the red cell was observed as increased accumulation of pyruvate, whereas accumulation of lactate represented storage of reducing equivalents. Exogenous lactate or pyruvate did not serve as a net electron source or sink since the total content in red cell suspensions of both lactate and pyruvate was increased during exposure to oxidative stress. If exogenous lactate had been used as a net source of reducing equivalents, the lactate concentration would have decreased during incubation of red cell suspensions. Plasma ascorbate or other constituents did not alter the qualitative response of glycolysis to oxidative stress (decreased lactate accumulation, increased pyruvate accumulation, and increased total flux through glycolysis), but plasma constituents did raise significantly the dose of oxidant agent required to elicit a given quantitative response. At levels of oxidative stress likely to be encountered in vivo, glycolysis and the hexose monophosphate shunt may be equal in importance as aerobic/antioxidant pathways
— id: 148886, year: 1984, vol: 33, page: 1417, stat: Journal Article,

Membrane protein changes induced by tert-butyl hydroperoxide in red blood cells
Sullivan, S G; Stern, A
1984 Jul 25;774(2):215-220, Biochimica & biophysica acta
Red cells were incubated in the presence of t-butyl hydroperoxide and effects on red cell membrane proteins were studied by SDS-polyacrylamide gel electrophoresis. t-Butyl hydroperoxide caused diminution in intensity of all major cytoskeletal bands with the concomitant formation of high molecular weight material. Membrane glycoproteins were unaffected. t-Butyl hydroperoxide increased hemoglobin binding to ghosts. After dissolution in SDS and beta-mercaptoethanol, membrane-bound hemoglobin appeared on the gels in the form of monomers and crosslinked polymers of hemoglobin or globin chains. Crosslinking was partially prevented by metabolism of t-butyl hydroperoxide by the hexose monophosphate shunt except in methemoglobin-containing red cells where reaction with methemoglobin accounted for most of the consumption of t-butyl hydroperoxide. Metal chelators, deferoxamine mesylate and diethylenetriaminepentaacetic acid, had no effect on membrane protein changes. Butylated hydroxytoluene, diphenylamine and ascorbate, compounds that inhibit t-butyl hydroperoxide-induced red cell membrane lipid peroxidation, had no effect on t-butyl hydroperoxide-induced membrane protein changes. These results suggest that membrane proteins and membrane lipids have different mechanisms of peroxidant damage
— id: 135303, year: 1984, vol: 774, page: 215, stat: Journal Article,

THE AUTOXIDATION OF GLYCERALDEHYDE AND OTHER SIMPLE MONOSACCHARIDES UNDER PHYSIOLOGICAL CONDITIONS CATALYZED BY BUFFER IONS
THORNALLEY, P; WOLFF, S; CRABBE, J; STERN, A
1984 ;797(2):276-287, Biochimica & biophysica acta
— id: 41107, year: 1984, vol: 797, page: 276, stat: Journal Article,

THE EFFECT OF GLYCERALDEHYDE ON RED-CELLS - HEMOGLOBIN STATUS, OXIDATIVE-METABOLISM AND GLYCOLYSIS
THORNALLEY, PJ; STERN, A
1984 ;804(3):308-323, Biochimica & biophysica acta
— id: 41070, year: 1984, vol: 804, page: 308, stat: Journal Article,

THE PRODUCTION OF FREE-RADICALS DURING THE AUTOXIDATION OF MONOSACCHARIDES BY BUFFER IONS
THORNALLEY, PJ; STERN, A
1984 ;134(2):191-204, Carbohydrate research
— id: 41265, year: 1984, vol: 134, page: 191, stat: Journal Article,

THE OXIDATION OF OXYHEMOGLOBIN BY GLYCERALDEHYDE AND OTHER SIMPLE MONOSACCHARIDES
THORNALLEY, PJ; WOLFF, SP; CRABBE, MJC; STERN, A
1984 ;217(3):615-622, Biochemical journal
— id: 41111, year: 1984, vol: 217, page: 615, stat: Journal Article,

Stimulation of ATP hydrolysis by chloroquine and primaquine in human red blood cells
Kelman, S N; Sullivan, S G; Stern, A
1983 Jun;29(3):379-384, Biochemical medicine
Primaquine, an 8-aminoquinoline, and chloroquine, a 4-aminoquinoline, both stimulate ATP hydrolysis in human red blood cells incubated in the absence of glucose. In the presence of glucose, ATP levels are partially maintained by increased flux of glucose through glycolysis. Glucose dependence of chloroquine uptake and the activity of primaquine as a redox reagent explain quantitative differences in ATP hydrolysis and accumulation of specific glycolytic products
— id: 148889, year: 1983, vol: 29, page: 379, stat: Journal Article,

Effects of physiologic concentrations of lactate, pyruvate and ascorbate on glucose metabolism in unstressed and oxidatively stressed human red blood cells
Sullivan, S G; Stern, A
1983 Oct 1;32(19):2891-2902, Biochemical pharmacology
Glucose metabolism was studied in human red blood cells incubated in the presence of physiologic concentrations of ascorbate (0.1 mM) and/or lactate (2 mM) plus pyruvate (0.1 mM). The total flux through glycolysis, as measured by 14C-labeling of glycolytic intermediates, was increased about 15% by ascorbate, 30% by lactate plus pyruvate, and 40% by ascorbate plus lactate plus pyruvate. We found, however, that physiologic concentrations of ascorbate and/or lactate plus pyruvate had no effect on flux of glucose or recycling of pentoses through the hexose monophosphate shunt. Increased formation of lactate accounted for most of the observed increase in glycolysis with little change in pyruvate formation, indicating that the increased flux of reducing equivalents from glucose was stored as lactate rather than being consumed by red cell metabolism. In all experiments, there was a net increase with time in the absolute amount of both lactate and pyruvate in red cell suspensions, indicating that lactate or pyruvate present at zero time did not function as a stoichiometric source or sink for reducing equivalents. There was little effect on steady-state levels of ATP or 2,3-diphosphoglycerate. Equilibration of ascorbate between red cells and the medium was complete before the addition of 14C-labeled glucose to the medium. Glucose metabolism prevented net oxidation of ascorbate in the incubation medium. Physiologic concentrations of ascorbate, lactate and pyruvate appear to increase flux through glycolysis by increasing the turnover of ATP and/or 2,3-diphosphoglycerate. Red cells were exposed to mild oxidative stress by incubation with 0.27 mM 6-hydroxydopamine, 0.27 mM 6-aminodopamine, 0.13 mM 1,4-naphthoquinone-2-sulfonic acid or 0.27 mM phenylhydrazine. The metabolic response to oxidative stress was determined by measuring the formation of methemoglobin, pyruvate, lactate and CO2 in the presence and absence of physiologic concentrations of lactate, pyruvate and ascorbate. Lactate, pyruvate and ascorbate had no effect on the net methemoglobin accumulation but rather on the distribution of the metabolic sources of reducing equivalents and on the flux of reducing equivalents to oxygen. Physiologic lactate and pyruvate allowed increased flow of reducing equivalents from glycolysis to methemoglobin and ultimately oxygen without the necessity of increased flux through glycolysis. This was accomplished by a decrease in the ratio of newly formed lactate to newly formed pyruvate with no increase in total lactate plus pyruvate.(ABSTRACT TRUNCATED AT 400 WORDS)
— id: 148887, year: 1983, vol: 32, page: 2891, stat: Journal Article,

Free radical involvement in the oxidative phenomena induced by tert-butyl hydroperoxide in erythrocytes
Thornalley, P J; Trotta, R J; Stern, A
1983 Aug 23;759(1-2):16-22, Biochimica & biophysica acta
Free radical involvement in the oxidative events induced by tert-butyl hydroperoxide in erythrocytes has been demonstrated by the use of the electron spin resonance technique of spin trapping with the spin trap 5.5-dimethyl-1-pyrroline-N-oxide (DMPO). The reactions of tert-butyl hydroperoxide with haemoglobins and intact cell systems were studied. Oxyhaemoglobin-containing system showed exclusive production of the t-butyloxy radical spin adduct of DMPO (DMPO-OBut), indicating t-butyloxy radical production. Methaemoglobin-containing systems showed the production of an oxidised derivative of DMPO, 5,5-dimethyl-2-ketopyrrolidino-1-oxyl (DMPOX)-previously associated with the generation of highly oxidised haem-iron. Carbon monoxyhaemoglobin-containing systems show the production of both DMPO-OBut and DMPOX but markedly slower than in either of the other haemoglobin systems. Generally, free radical production in haemoglobin systems was faster than in intact cell systems, indicating a membrane transport rate-limiting step for the tert-butyl hydroperoxide-mediated effects. Data from the use of free radical scavengers to inhibit DMPO-OBut production was consistent with the known reactivities of the scavengers toward t-butyloxy radicals. These and previously reported results (Trotta, R. J., Sullivan, S. G. and Stern, A. (1981) Biochim. Biophys. Acta 679, 230-237 and (1982) Biochem. J. 204, 405-415) implicate important roles for t-butyloxy radicals and haem intermediates in tert-butyl hydroperoxide-induced lipid peroxidation and haemoglobin oxidation in erythrocytes, respectively
— id: 135301, year: 1983, vol: 759, page: 16, stat: Journal Article,

A MECHANISM FOR PRIMAQUINE MEDIATED OXIDATION OF NADPH IN RED- BLOOD-CELLS
Thornalley, PJ; Stern, A; Bannister, JV
1983 ;32(23):3571-3575, Biochemical pharmacology
— id: 30592, year: 1983, vol: 32, page: 3571, stat: Journal Article,

Lipid peroxidation and haemoglobin degradation in red blood cells exposed to t-butyl hydroperoxide. The relative roles of haem- and glutathione-dependent decomposition of t-butyl hydroperoxide and membrane lipid hydroperoxides in lipid peroxidation and haemolysis
Trotta, R J; Sullivan, S G; Stern, A
1983 Jun 15;212(3):759-772, Biochemical journal
Red cells exposed to t-butyl hydroperoxide undergo lipid peroxidation, haemoglobin degradation and hexose monophosphate-shunt stimulation. By using the lipid-soluble antioxidant 2,6-di-t-butyl-p-cresol, the relative contributions of t-butyl hydroperoxide and membrane lipid hydroperoxides to oxidative haemoglobin changes and hexose monophosphate-shunt stimulation were determined. About 90% of the haemoglobin changes and all of the hexose monophosphate-shunt stimulation were caused by t-butyl hydroperoxide. The remainder of the haemoglobin changes appeared to be due to reactions between haemoglobin and lipid hydroperoxides generated during membrane peroxidation. After exposure of red cells to t-butyl hydroperoxide, no lipid hydroperoxides were detected iodimetrically, whether or not glucose was present in the incubation. Concentrations of 2,6-di-t-butyl-p-cresol, which almost totally suppressed lipid peroxidation, significantly inhibited haemoglobin binding to the membrane but had no significant effect on hexose monophosphate shunt stimulation, suggesting that lipid hydroperoxides had been decomposed by a reaction with haem or haem-protein and not enzymically via glutathione peroxidase. The mechanisms of lipid peroxidation and haemoglobin oxidation and the protective role of glucose were also investigated. In time-course studies of red cells containing oxyhaemoglobin, methaemoglobin or carbonmono-oxyhaemoglobin incubated without glucose and exposed to t-butyl hydroperoxide, haemoglobin oxidation paralleled both lipid peroxidation and t-butyl hydroperoxide consumption. Lipid peroxidation ceased when all t-butyl hydroperoxide was consumed, indicating that it was not autocatalytic and was driven by initiation events followed by rapid propagation and termination of chain reactions and rapid non-enzymic decomposition of lipid hydroperoxides. Carbonmono-oxyhaemoglobin and oxyhaemoglobin were good promoters of peroxidation, whereas methaemoglobin relatively spared the membrane from peroxidation. The protective influence of glucose metabolism on the time course of t-butyl hydroperoxide-induced changes was greatest in carbonmono-oxyhaemoglobin-containing red cells followed in order by oxyhaemoglobin- and methaemoglobin-containing red cells. This is the reverse order of the reactivity of the hydroperoxide with haemoglobin, which is greatest with methaemoglobin. In studies exposing red cells to a wide range of t-butyl hydroperoxide concentrations, haemoglobin oxidation and lipid peroxidation did not occur until the cellular glutathione had been oxidized. The amount of lipid peroxidation per increment in added t-butyl hydroperoxide was greatest in red cells containing carbonmono-oxyhaemoglobin, followed in order by oxyhaemoglobin and methaemoglobin. Red cells containing oxyhaemoglobin and carbonmono-oxyhaemoglobin and exposed to increasing concentrations of t-butyl hydroperoxide became increasingly resistant to lipid peroxidation as methaemoglobin accumulated, supporting a relatively protective role for methaemoglobin. In the presence of glucose, higher levels of t-butyl hydroperoxide were required to induce lipid peroxidation and haemoglobin oxidation compared with incubations without glucose. Carbonmono-oxyhaemoglobin-containing red cells exposed to the highest levels of t-butyl hydroperoxide underwent haemolysis after a critical level of lipid peroxidation was reached. Inhibition of lipid peroxidation by 2,6-di-t-butyl-p-cresol below this critical level prevented haemolysis. Oxidative membrane damage appeared to be a more important determinant of haemolysis in vitro than haemoglobin degradation. The effects of various antioxidants and free-radical scavengers on lipid peroxidation in red cells or in ghosts plus methaemoglobin exposed to t-butyl hydroperoxide suggested that red-cell haemoglobin decomposed the hydroperoxide by a homolytic scission mechanism to t-butoxyl radicals
— id: 148888, year: 1983, vol: 212, page: 759, stat: Journal Article,

Primaquine-mediated oxidative metabolism in the human red cell. Lack of dependence on oxyhemoglobin, H2O2 formation, or glutathione turnover
Kelman, S N; Sullivan, S G; Stern, A
1982 Jul 15;31(14):2409-2414, Biochemical pharmacology
Stimulation of the hexose monophosphate shunt by primaquine results from the oxidation of NADPH by primaquine. This conclusion was based on the observations that primaquine lowered cellular NADPH but not GSH and that, in red cells in which the GSH was unavailable for reaction, primaquine still stimulated the rate of the hexose monophosphate shunt. In a non-cellular system, primaquine interacted with NADPH, but not GSH, to produce H2O2. Stimulation of the hexose monophosphate shunt by primaquine does not primarily involve H2O2 accumulation since stimulation of the pathway by primaquine was also observed in red cells containing methemoglobin, a red cell preparation in which no H2O2 accumulates. Methemoglobin prevented the formation and/or accumulation of H2O2 in intact red cells incubated with primaquine as well as in a non-cellular system containing primaquine plus Fe2+-EDTA as an H2O2 source. Methemoglobin probably acts by scavenging reactive intermediates since oxyhemoglobin was formed from methemoglobin in the non-cellular experiments. In the red cell, primaquine stimulated glucose-dependent conversion of methemoglobin to oxyhemoglobin
— id: 148891, year: 1982, vol: 31, page: 2409, stat: Journal Article,

Effects of ascorbate on methemoglobin reduction in intact red cells
Sullivan, S G; Stern, A
1982 Feb;213(2):590-594, Archives of biochemistry & biophysics. ABB
— id: 148893, year: 1982, vol: 213, page: 590, stat: Journal Article,

Factors affecting unstimulated flux through the hexose monophosphate shunt during incubations of human red blood cells
Trotta, R J; Sullivan, S G; Stern, A
1982 Oct;31(10):1052-1056, Metabolism clinical & experimental
— id: 148890, year: 1982, vol: 31, page: 1052, stat: Journal Article,

Lipid peroxidation and haemoglobin degradation in red blood cells exposed to t-butyl hydroperoxide. Effects of the hexose monophosphate shunt as mediated by glutathione and ascorbate
Trotta, R J; Sullivan, S G; Stern, A
1982 May 15;204(2):405-415, Biochemical journal
Lipid peroxidation and haemoglobin degradation were the two extremes of a spectrum of oxidative damage in red cells exposed to t-butyl hydroperoxide. The exact position in this spectrum depended on the availability of glucose and the ligand state of haemoglobin. In red cells containing oxy- or carbonmono-oxy-haemoglobin, hexose monophosphate-shunt activity was mainly responsible for metabolism of t-butyl hydroperoxide; haem groups were the main scavengers in red cells containing methaemoglobin. Glutathione, via glutathione peroxidase, accounted for nearly all of the hydroperoxide metabolizing activity of the hexose monophosphate shunt. Glucose protection against lipid peroxidation was almost entirely mediated by glutathione, whereas glucose protection of haemoglobin was only partly mediated by glutathione. Physiological concentrations of intracellular or extracellular ascorbate had no effect on consumption of t-butyl hydroperoxide or oxidation of haemoglobin. Ascorbate was mainly involved in scavenging chain-propagating species involved in lipid peroxidation. The protective effect of intracellular ascorbate against lipid peroxidation was about 100% glucose-dependent and about 50% glutathione-dependent. Extracellular ascorbate functioned largely without a requirement for glucose metabolism, although some synergistic effects between extracellular ascorbate and glutathione were observed. Lipid peroxidation was not dependent on the rate or completion of t-butyl hydroperoxide consumption but rather on the route of consumption. Lipid peroxidation appears to depend on the balance between the presence of initiators of lipid peroxidation (oxyhaemoglobin and low concentrations of methaemoglobin) and terminators of lipid peroxidation (glutathione, ascorbate, high concentrations of methaemoglobin)
— id: 148892, year: 1982, vol: 204, page: 405, stat: Journal Article,

Chloroquine- and primaquine-induced alterations of glucose metabolism in the uninfected red cell
Kelman, S N; Sullivan, S G; Stern, A
1981 Jan 1;30(1):81-87, Biochemical pharmacology
— id: 148895, year: 1981, vol: 30, page: 81, stat: Journal Article,

Effects of superoxide dismutase and catalase on catalysis of 6-hydroxydopamine and 6-aminodopamine autoxidation by iron and ascorbate
Sullivan, S G; Stern, A
1981 Aug 15;30(16):2279-2285, Biochemical pharmacology
— id: 148894, year: 1981, vol: 30, page: 2279, stat: Journal Article,

Lipid peroxidation and hemoglobin degradation in red blood cells exposed to t-butyl hydroperoxide. Dependence on glucose metabolism and hemoglobin status
Trotta, R J; Sullivan, S G; Stern, A
1981 Dec 4;678(2):230-237, Biochimica & biophysica acta
Changes in hemoglobin status and lipid peroxidation were followed in red cells containing either oxy-met-, or carbonmonoxyhemoglobin, incubated with t-butyl hydroperoxide in a medium with or without glucose. Loss of intact hemoglobin (the sum of oxyhemoglobin and methemoglobin) was inversely proportional to the degree of lipid peroxidation in red cells containing either oxy- or methemoglobin. When glucose was added to the medium, lipid peroxidation increased while there was a decreased loss of intact hemoglobin in red cells containing either oxy- or methemoglobin, while both lipid peroxidation and changes in hemoglobin decreased in red cells containing carbonmonoxyhemoglobin. Methemoglobin formation and loss of intact hemoglobin were directly proportional to the degree of lipid peroxidation in red cells containing carbonmonoxyhemoglobin. The greatest amount of lipid peroxidation occurred in red cells containing carbonmonoxyhemoglobin, incubated without glucose. These results indicate that methemoglobin and non-intact hemoglobin may protect the membrane against lipid peroxidation. We propose that, depending on the availability of glucose and the liganded state of hemoglobin, lipid peroxidation and hemoglobin alterations represent extremes of a spectrum of oxidative damage
— id: 135300, year: 1981, vol: 678, page: 230, stat: Journal Article,

CARBON-MONOXIDE - GENERAL DISCUSSION
EISENBUD, M; COBURN, R; STERN, A; HORVATH, S; HINKLE, L
1980 ;56(9):829-834, Bulletin of the New York Academy of Medicine
— id: 40285, year: 1980, vol: 56, page: 829, stat: Journal Article,

Interdependence of hemoglobin, catalase and the hexose monophosphate shunt in red blood cells exposed to oxidative agents
Sullivan, S G; Stern, A
1980 Sep 1;29(17):2351-2359, Biochemical pharmacology
— id: 148896, year: 1980, vol: 29, page: 2351, stat: Journal Article,

The detection of superoxide anion from the reaction of oxyhemoglobin and phenylhydrazine using EPR spectroscopy
Goldberg, B; Stern, A; Peisach, J; Blumberg, W E
1979 Apr 15;35(4):488-489, Experientia
The low temperature EPR spectrum of a quickly reacted mixture of oxyhemoglobin and phenylhydrazine was studied. With the use of a computer, the spectral contribution of methemoglobin in the region of g = 2 was subtracted. The remaining spectrum was that of an axial free radical (g perpendicular = 2.00, g parallel = 2.06) having the magnetic parameters of superoxide anion. In the presence of superoxide dismutase, this axial radical was not seen, confirming that superoxide anion is indeed generated by the reaction
— id: 133057, year: 1979, vol: 35, page: 488, stat: Journal Article,

The interrelationship of superoxide dismutase and peroxidatic enzymes in the red cell
McMahon, S; Stern, A
1979 Feb 9;566(2):253-258, Biochimica & biophysica acta
Activities of superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) and catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase, EC 1.11.1.6) were determined during the course of incubation of red cell suspensions with 1,4-naphthoquinone-2-sulfonic acid. In the absence of glucose, incubation with napthoquinone sulfonate resulted in an inhibition of catalase and superoxide dismutase. The catalase inhibitor, 3-amino-1,2,4-triazole enhanced inactivation of catalase in the presence of naphthoquinone sulfonate and this in turn led to augmented inhibition of superoxide dismutase. The presence of glucose in the incubation medium prevented napthoquinone sulfonate-induced enzyme inhibition in the absence of aminotriazole, but had little effect in the presence of aminotriazole. The relevance of these findings to the cellular interrelationship of peroxidatic enzymes and superoxide dismutase is discussed
— id: 135296, year: 1979, vol: 566, page: 253, stat: Journal Article,

Restoration of red cell catalase activity by glucose metabolism after exposure to a vitamin K analog
Sullivan, S G; McMahon, S; Stern, A
1979 Dec 1;28(23):3403-3407, Biochemical pharmacology
— id: 148897, year: 1979, vol: 28, page: 3403, stat: Journal Article,

Analogous effect of protons and inositol hexaphosphate on the alteration of structure of nitrosyl fetal human hemoglobin
Chevion, M; Stern, A; Peisach, J; Blumberg, W E; Simon, S
1978 May 2;17(9):1745-1750, Biochemistry
We have determined the low temperature EPR spectra and room temperature ligand dissociation rate constants of human NO-hemoglobins F and A as a function of pH and inositol hexaphosphate levels in order to assess the contribution of a quaternary structural equilibrium in the two proteins to their spectral and functional properties. Our results are consistent with an increased stability of a ligated low affinity structure in the fetal protein; the functional properties of this structure appear to be essentially the same in the two hemoglobins, even though its stability relative to a high affinity conformation is different. The pH dependence of the NO dissociation constant in both adult and fetal hemoglobin can be assigned primarily to the pH-dependent equilibria of high and low affinity forms as monitored by EPR
— id: 133064, year: 1978, vol: 17, page: 1745, stat: Journal Article,

MECHANISM OF OXIDATIVE HEMOLYSIS PRODUCED BY PHENYLHYDRAZINE
Goldberg, B; Stern, A
1977 ;13(5):832-839, Molecular pharmacology
— id: 29530, year: 1977, vol: 13, page: 832, stat: Journal Article,

ROLE OF SUPEROXIDE ANION AS A TOXIC SPECIES IN ERYTHROCYTE
Goldberg, B; Stern, A
1977 ;178(1):218-225, Archives of biochemistry & biophysics. ABB
— id: 29551, year: 1977, vol: 178, page: 218, stat: Journal Article,

SUPEROXIDE ANION AND DRUG-INDUCED HEMOLYSIS
Goldberg, B; Stern, A
1977 ;36(5-6):731-734, Acta biologica & medica Germanica
— id: 29512, year: 1977, vol: 36, page: 731, stat: Journal Article,

COMPARISON OF HUMAN ADULT AND FETAL HEMOGLOBIN - AMINOPHENOL- INDUCED METHEMOGLOBIN FORMATION
Wind, M; Stern, A
1977 ;33(11):1500-1501, Experientia
— id: 29514, year: 1977, vol: 33, page: 1500, stat: Journal Article,

PRODUCTION OF SUPEROXIDE ANION DURING OXIDATION OF HEMOGLOBIN BY MENADIONE
Goldberg, B; Stern, A
1976 ;437(2):628-632, Biochimica & biophysica acta
— id: 29420, year: 1976, vol: 437, page: 628, stat: Journal Article,

ROLE OF SUPEROXIDE ANION IN HEMOGLOBIN DESTRUCTION AND LYSIS IN ERYTHROCYTES EXPOSED TO DIHYDROXYFUMARIC ACID
Goldberg, B; Stern, A
1976 ;35(7):1606-1606, Federation Proceedings (Federation of American Societies for Experimental Biology)
— id: 29473, year: 1976, vol: 35, page: 1606, stat: Journal Article,

SUPEROXIDE ANION AS A MEDIATOR OF DRUG-INDUCED OXIDATIVE HEMOLYSIS
Goldberg, B; Stern, A
1976 ;251(20):6468-6470, Journal of biological chemistry
— id: 29437, year: 1976, vol: 251, page: 6468, stat: Journal Article,

MECHANISM OF SUPEROXIDE ANION GENERATION BY INTERACTION OF PHENYLHYDRAZINE WITH HEMOGLOBIN
Goldberg, B; Stern, A; Peisach, J
1976 ;251(10):3045-3051, Journal of biological chemistry
— id: 29425, year: 1976, vol: 251, page: 3045, stat: Journal Article,

METOLAZONE, A DIURETIC AGENT
Stern, A
1976 ;91(2):262-263, American heart journal
— id: 29432, year: 1976, vol: 91, page: 262, stat: Journal Article,

RELATIVE STABILITIES OF 2 QUATERNARY CONFORMATIONS OF HUMAN FETAL HEMOGLOBIN
Wind, M; Stern, A; Law, L; Simon, S
1976 ;15(23):5161-5167, Biochemistry
— id: 29409, year: 1976, vol: 15, page: 5161, stat: Journal Article,

GENERATION OF O-2 BY INTERACTION OF HEMOLYTIC AGENT, PHENYLHYDRAZINE, WITH HUMAN HEMOGLOBIN
Goldberg, B; Stern, A
1975 ;250(6):2401-2403, Journal of biological chemistry
— id: 28686, year: 1975, vol: 250, page: 2401, stat: Journal Article,

BINDING OF PHENOTHIAZINES TO OXYHEMOGLOBIN A AND S
WIND, M; BERLINER, A; STERN, A
1973 ;5(3):759-766, Research communications in chemical pathology & pharmacology
— id: 39797, year: 1973, vol: 5, page: 759, stat: Journal Article,