• Acetylation of the Pro-Apoptotic Factor, p53 in the Hippocampus following Cerebral Ischemia and Modulation by Estrogen

      Raz, Limor; Zhang, Quan-Guang; Han, Dong; Dong, Yan; De Sevilla, Liesl; Brann, Darrell W; Institute of Molecular Medicine and Genetics (2011-10-26)
      Background: Recent studies demonstrate that acetylation of the transcription factor, p53 on lysine373 leads to its enhanced stabilization/activity and increased susceptibility of cells to stress. However, it is not known whether acetylation of p53 is altered in the hippocampus following global cerebral ischemia (GCI) or is regulated by the hormone, 17b-estradiol (17b2E2), and thus, this study examined these issues.
    • An Improved Test for Detecting Multiplicative Homeostatic Synaptic Scaling

      Kim, Jimok; Tsien, Richard W.; Alger, Bradley E.; Institute of Molecular Medicine and Genetics; Graduate Program in Neuroscience; Department of Neurology (2012-05-17)
      Homeostatic scaling of synaptic strengths is essential for maintenance of network "gain", but also poses a risk of losing the distinctions among relative synaptic weights, which are possibly cellular correlates of memory storage. Multiplicative scaling of all synapses has been proposed as a mechanism that would preserve the relative weights among them, because they would all be proportionately adjusted. It is crucial for this hypothesis that all synapses be affected identically, but whether or not this actually occurs is difficult to determine directly. Mathematical tests for multiplicative synaptic scaling are presently carried out on distributions of miniature synaptic current amplitudes, but the accuracy of the test procedure has not been fully validated. We now show that the existence of an amplitude threshold for empirical detection of miniature synaptic currents limits the use of the most common method for detecting multiplicative changes. Our new method circumvents the problem by discarding the potentially distorting subthreshold values after computational scaling. This new method should be useful in assessing the underlying neurophysiological nature of a homeostatic synaptic scaling transformation, and therefore in evaluating its functional significance.
    • Role of Rac1 GTPase in NADPH Oxidase Activation and Cognitive Impairment Following Cerebral Ischemia in the Rat

      Raz, Limor; Zhang, Quan-Guang; Zhou, Cai-feng; Han, Dong; Gulati, Priya; Yang, Li-cai; Yang, Fang; Wang, Rui-min; Brann, Darrell W; Institute of Molecular Medicine and Genetics (2010-09-7)
      Background: Recent work by our laboratory and others has implicated NADPH oxidase as having an important role in reactive oxygen species (ROS) generation and neuronal damage following cerebral ischemia, although the mechanisms controlling NADPH oxidase in the brain remain poorly understood. The purpose of the current study was to examine the regulatory and functional role of the Rho GTPase, Rac1 in NADPH oxidase activation, ROS generation and neuronal cell death/cognitive dysfunction following global cerebral ischemia in the male rat.