Steven G. Kohama

Increased lifespan has led to a dramatic increase in the number of elderly, which coupled with advanced age, is associated with an increase in fragility and increased susceptibility to disease.  In the face of the projected healthcare costs associated an expanding aged population, an immediate goal of aging research is to extend "healthspan", or the amount of time where functionality is maintained in the aged. The nonhuman primate, not surprisingly, mimics many aspects of human aging and therefore provides an ideal model system to examine the underlying mechanisms that influence aging. Moreover, understanding these complex interactions can also afford an opportunity to explore interventions in this model for translational research.

Steven Kohama, Ph.D., heads the Aging Nonhuman Primate Resource at ONPRC, whose primary goals are to manage and maintain a population of aged rhesus macaques and provide support for their use in basic and clinically-related research in the field of aging. Both goals go hand-in-hand, as regulating the availability of aged animals is a challenge, especially when fulfilling specific phenotypes for a wide-variety of research topics. This effort is supported financially by both the National Institute on Aging, as well as contributions from ONPRC. The recognition that aging research will be critical for addressing the needs of the expanding aged population, coupled with widespread scientific interest, has helped to identify aging as an important cornerstone of research at ONPRC.

Aging research at ONPRC, like the process itself, encompasses a wide breadth of areas. Studies have traditionally reflected broad areas of research strengths at our Center and OHSU. These areas of focus include reproductive senescence, the decline of immune function, special senses(vision), and the effects of aging on the central nervous system. As mentioned above, many of these studies have focused on a variety of treatments,including hormone and growth factor therapy. The effects of lifestyle have also been examined, including those of a Western-style diet on aged animals, looking at the effect on metabolism. Models of neurodegeneration, such as cerebralischemia have also been ongoing for several years, which have included comparisons of young and old, male and female animals. Many of these studies are multi-disciplinary, as the interaction of aging and various manipulations are frequently ideal for the examination of several target organ systems.  Coordination and management of the resource and research projects, coupled with the many tools available at the Center (for example, gene array, proteomics, MRI),provides a dynamic and potent environment for aging research.

 

BIOGRAPHY

Steven Kohama is a Senior Staff Scientist in the Division of Neuroscience and has been Head of the Aging Resource since 1999. He has a B.A. in Biological Sciences from UCLA and a M.S. from CSULA, where he studied the interactions of the reproductive and immune systems. He then studied mechanisms of neuroendocrine aging at the Andrus Gerontology Center at USC, where he received his Ph.D. in the Department of Neurobiology. Post-doctoral work was conducted at ONPRC, concentrating on ovarian steroid hormone effects on gene regulation in the brain. Following a promotion to Staff Scientist in 1994 and later heading the effort for creating the Aging Resource, he has continued to work on age-related changes in the nonhuman primate model.

 

KEY PUBLICATIONS

Bahjat RF, Williams-Karnesky RL, Kohama SG, West GA, Doyle KP, Spector MD, Hobbs TR and Stenzel-Poore M. (2011) Proof of Concept: Pharmacological preconditioning with a Toll-like receptor agonist protects against cerebrovascular injury in a primate model of stroke. J Cerebral Blood Flow Metab. 31:1229-1242. PMID: 21285967

Kohama SG, Rosene DL and Sherman LS. (2012) Age-related changes in human and nonhuman primate white matter: from myelination disturbances to cognitive decline. AGE. 34:1093-1110. PMID: 22203458

Cargill R, Kohama SG, Struve J, Su W, Banine F, Witkowski E and Back S. (2012) Astrocytes in aged nonhuman primate brain gray matter synthesize excess hylauronan. Neurobiol Aging. 33(4):860e13-24. PMID: 21872361

Gesuete R, Kohama SG, Stenzel-Poore M (2014) Toll-like receptors and ischemic brain injury. J Neuropathol Exp Neurol. 73:378-386. PMID: 24709682

Khan AR, Cornea A, Leigland LA, Kohama SG, Jespersen SN, Kroenke CD (2015) 3D structure tensor analysis of light microscopy data for validating diffusion MRI. NeuroImage 111:192-203. PMID: 25665963

Bethea CL, Kohama SG, Reddy AP, Urbanski HF (2015) Ovarian steroids regulate gene expression in the dorsal raphe of old female macaques. Neurobiol Aging 37:179-191. PMCID: PMC4699313

See a full listing of Dr. Kohama's publications.