Current Research
An important focus of our work is Campylobacter fetus, a pathogen of animals and humans. C. fetus cells are covered with S-layer proteins that allow the organisms to escape complement-mediated lysis, and that undergo antigenic variation. Exploring the molecular basis of variation, we have found that the S-layer proteins are encoded by a family of sapA homologs tightly clustered on the chromosome, and that a high frequency DNA inversion plays a critical role in variation. The inversion shows elements of both site-specific and homologous recombination. This is a highly tractable system to examine DNA recombination mechanisms, as well as for structure-function analysis of protein-carbohydrate (LPS) interactions, and the structural basis of antigenicity.
Finally, we are using PCR with conserved 165 ribosomal RNA specificities to define at a molecular level, the bacteria (and fungi) that are normally present in human host mileaus ... [more]
Diseases date back to the dawn of humankind. As humans have evolved, so too have their diseases: some that were once rare have become common, others have disappeared and new varieties have emerged. Many of these changes have taken place in the wake of important transformations in human civilizations and ecology. It is therefore feasible to propose that diseases succeed and fail in response to humanity's advances. ... 
The common theme in our work is the effect on disease states by the microbial pressure that arises when a patient's symbiotic bacterial biota is altered. Increasing evidence suggests an important role for chronic inflammation in many disease conditions associated with aging, such as atherosclerosis, cancers, diabetes, and even autoimmune diseases. The body contains about ten times as many commensal bacteria as human cells ... 
Our current work focuses on the role of gut derived obesity peptides such as leptin and ghrelin in gastrointestinal health and disease. The prevalence of obesity continues to rise along with its associated adverse effects on health. Epidemiologic studies have demonstrated a link between obesity and gastroesophageal reflux, Barrett’s esophagus, esophageal adenocarcinoma, as well as colon cancer. Our goal is ... 
My major interest is in bacterial infections that continue to be a major public health problem around the world. The major areas of research in our laboratory include the microbiology, pathogenesis and epidemiology of bacterial enteric diseases. Our current research focuses on the study of the gram negative bacteria Helicobacter pylori and Campylobacter jejuni. H. pylori is among the most common bacteria that colonize humans ... 
Estrogen, essential for human health and reproduction, plays a role in malignancies such as Type I endometrial carcinoma, and forms of breast and ovarian cancer. The clinical success of anti-estrogen therapies including tamoxifen and aromatase-inhibitors, speaks to the centrality of estrogens in estrogen receptor-expressing breast cancers. Epidemiologic data has similarly implicated states of estrogen excess, such as obesity, nulliparity, early menarche, and late age at menopause as risks for the development of estrogen-related cancers. ... 
My current research focuses on the role of the gut microbiome in various disease conditions such as colorectal neoplasia and obesity. The number of bacteria that reside within the human gastrointestinal tract outnumbers the number of human cells by a factor of 10 and the aggregate genetic information contained within those bacteria is several magnitudes greater than that found in the host human genome ...