Obesity-linked Kidney Disease
Obesity is one of the major causes of mortality in the United States and negatively impacts quality of life. Unfortunately, the incidence of obesity is on the rise in all segments and age groups of our society with over 60% of the adult population now considered clinically obese or overweight. Health risks associated with obesity include high blood pressure, cardiovascular disease, high blood lipid levels, and type II diabetes. These are all risk factors for the development of kidney disease as well. A large percentage of patients requiring dialysis or kidney transplantation suffer from hypertension, type II diabetes, high blood lipid levels, and excess body weight. Indeed, diabetes and hypertension are the leading causes of need for dialysis and transplantation in this country.
Dr. Maddox is examining the pathways that lead to obesity-linked kidney disease. He utilizes dietary and pharmacological interventions to prevent or slow the progression of kidney disease. He then examines the physiological and molecular mechanisms involved both in the development and prevention of obesity-linked kidney disease.
His most recent results were published in the January and July 2002 issues of Kidney International, the prestigious journal of the International Society of Nephrology, and in the October 2004 issue of Diabetologia and were presented at the American Society of Nephrology annual meetings in November 2005 in Philadelphia. His work is funded by a VA Merit Review grant.
Control of Kidney Filtration and Growth
Dr. Karen A. Munger recently joined the group in September 2005. She is a renal physiologist from the University of California San Diego and the VA Medical Center, San Diego. Her past work included studies of kidney function in pregnancy, hormonal and renal nerve control of kidney filtration rate, treatment of renal disease with gene therapy, the role of amino acid metabolism during sepsis, and regulation of kidney growth during diabetes.
She recently discovered the presence of a chemical receptor in the kidney that appears to be involved in the regulation of kidney filtration rate in response to protein intake and she has been awarded a major grant from the National Institutes of Health to pursue these studies.
Her most recent publications have been in Kidney International, American Journal of Physiology, Nephron Journals, and the Journal of Nephrology . Her work was presented at the American Society of Nephrology in November 2005, the American Heart Association in November 2005, and at the Experimental Biology meetings in San Francisco in April 2006. Dr. Munger chaired scientific sessions at each of those meetings.
Stress is an epidemic problem confronting our society. Psychosocial and environmental stressors are known risk factors for a variety of disorders including depression and addiction and may cause or exacerbate sleep disorders such as insomnia and narcolepsy. In any given 1-year period, 9.5 percent of the population, or about 18.8 million American adults, suffer from a depressive illness. Understanding the underlying stress-responsive networks in the brain will lead to better treatment of these disorders.
Dr. Patrick Ronan uses molecular biology techniques coupled with animal behavior models to study the relationship between stress and these brain disorders with a particular interest in the role of a stress-related hormone/neurotransmitter called corticotropin releasing factor (CRF). His recent publication in the top-ranked Journal of Neuroscience describes the characterization of a local gene deletion in a mammalian brain using an adeno-associated viral vector.
Presently, Dr. Ronan is working on a number of projects, including locally silencing specific genes (e.g. CRF) in various brain regions in order to understand their role in the stress response. His newest focus is in the area of addiction, specifically with respect to the role of stress in cocaine addiction. CRF has been implicated in the anxiety associated with withdrawal from cocaine as well as in stress-induced relapse. He and his group are presently characterizing the CRF system in various regions of the brain associated with cocaine abuse and withdrawal.
Dr. Ronan was recently awarded a grant from the National Institutes of Health to study this topic. He is one of 5 Project Directors on a 5-year $9.5 million Center of Biomedical Research Excellence (COBRE) grant focusing on neural mechanisms of adaptation.