Veterans Health Administration

About: Veterans Health Administration is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Population & Veterans Affairs. The organization has 63820 authors who have published 98417 publications receiving 4835425 citations. The organization is also known as: VHA.

Fractional differentiation by neocortical pyramidal neurons.

Abstract: Neural systems adapt to changes in stimulus statistics. The authors find that neocortical pyramidal neurons adapt with a time scale that depends on the time scale of changes in stimulus statistics, and that for individual neurons the firing is a fractional derivative of slowly varying stimulus parameters. Neural systems adapt to changes in stimulus statistics. However, it is not known how stimuli with complex temporal dynamics drive the dynamics of adaptation and the resulting firing rate. For single neurons, it has often been assumed that adaptation has a single time scale. We found that single rat neocortical pyramidal neurons adapt with a time scale that depends on the time scale of changes in stimulus statistics. This multiple time scale adaptation is consistent with fractional order differentiation, such that the neuron's firing rate is a fractional derivative of slowly varying stimulus parameters. Biophysically, even though neuronal fractional differentiation effectively yields adaptation with many time scales, we found that its implementation required only a few properly balanced known adaptive mechanisms. Fractional differentiation provides single neurons with a fundamental and general computation that can contribute to efficient information processing, stimulus anticipation and frequency-independent phase shifts of oscillatory neuronal firing.

Thiazolidinediones expand body fluid volume through PPARγ stimulation of ENaC-mediated renal salt absorption

Abstract: Thiazolidinediones (TZDs) are widely used to treat type 2 diabetes mellitus; however, their use is complicated by systemic fluid retention. Along the nephron, the pharmacological target of TZDs, peroxisome proliferator-activated receptor-gamma (PPARgamma, encoded by Pparg), is most abundant in the collecting duct. Here we show that mice treated with TZDs experience early weight gain from increased total body water. Weight gain was blocked by the collecting duct-specific diuretic amiloride and was also prevented by deletion of Pparg from the collecting duct, using Pparg (flox/flox) mice. Deletion of collecting duct Pparg decreased renal Na(+) avidity and increased plasma aldosterone. Treating cultured collecting ducts with TZDs increased amiloride-sensitive Na(+) absorption and Scnn1g mRNA (encoding the epithelial Na(+) channel ENaCgamma) expression through a PPARgamma-dependent pathway. These studies identify Scnn1g as a PPARgamma target gene in the collecting duct. Activation of this pathway mediates fluid retention associated with TZDs, and suggests amiloride might provide a specific therapy.

Persisting consequences of stroke measured by the stroke impact scale

Abstract: Background and Purpose— The purpose of this study was to compare disability and quality of life as measured by the Stroke Impact Scale (SIS) of stroke patients deemed recovered (Barthel Index ≥95) with 2 stroke-free populations of community-dwelling elderly. Methods— Eighty-one stroke patients who participated in the Kansas City Stroke Registry and achieved a Barthel Index of ≥95 at 3 months after stroke and 246 stroke-free subjects enrolled in the Community Elders Study were enrolled in this study. The Community Elders Study group was further divided into 2 groups, those recruited from the Department of Veterans Affairs Health System (VA) and a those from a local health maintenance organization (HMO). Stroke patients were administered the SIS ≈90 days after stroke, and the stroke-free community dwellers were administered a version of the SIS adapted for nonstroke subjects, the Health Impact Scale (HIS). A general linear model was used to examine differences in health outcomes measured by the SIS or HIS b...