Talia R Walker

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Brainstem gliomas (BSG) are a rare group of central nervous system tumors that arise mostly in children and usually portend a particularly poor prognosis. We report the development of a genetically engineered mouse model of BSG using the RCAS/tv-a system and its implementation in preclinical trials. Using immunohistochemistry, we found that platelet-derived(More)
A characteristic response of cells subjected to a stress stimulus is a rapid activation of cellular glucose transport. The mechanisms governing this increase in glucose transport are poorly understood, but it has been suggested that the response may involve the intracellular-signaling components that also participate in the hormonal activation of glucose(More)
Phosphatidylinositol 3-kinase (PI3k) activity is required for the insulin stimulation of glucose transport in adipocytes and Chinese hamster ovary cells. Wortmannin (WM), an inhibitor of PI3k, inhibits the stimulation of glucose transport by insulin and the gain of glucose transporters at the cell surface. However, the effect of inhibition of PI3k on the(More)
We have investigated the action of a novel inhibitor of DG-kinase, R59949. This agent was found to produce partial inhibition of formation of phosphatidic acid in human platelets challenged with thrombin, DC8 or OAG. However, this effect was not associated with enhanced phosphorylation of a 47 kDa protein, a known substrate for protein kinase C. We(More)
The aim of this study was to establish further the role of protein kinase C in aggregation and secretion of 5-hydroxytryptamine (5-HT) from human platelets by using the selective inhibitor Ro 31-8220. Ro 31-8220 (3 microM) inhibited completely phosphorylation of pleckstrin, the major protein kinase C substrate, induced by thrombin, A23187 or phorbol(More)
By contrast with mammalian beta-adrenergic receptors, the avian isoform elicits two distinct effector responses, activation of adenylate cyclase and polyphosphoinositide-specific phospholipase C (PLC) leading to the accumulation of both cyclic adenosine monophosphate (cyclic AMP) and inositol phosphates. We have investigated the mechanisms of(More)
We report that activation of phospholipase C (PLC) by cross-linking of the platelet low-affinity Fc gamma receptor II (Fc gamma RII) is inhibited by two structurally distinct tyrosine kinase inhibitors, staurosporine and ST271. This contrasts with PLC activation induced by thrombin and U46619, a thromboxane mimetic, whose receptors have seven transmembrane(More)
Vanadate ions in the presence of H2O2 (peroxovanadate) induce a marked increase in the degree of tyrosine phosphorylation of proteins in human platelets. This increase preceded the onset of platelet shape change and aggregation, and is associated with activation of phospholipase C and increased [32P]phosphorylation of proteins of 47 kDa, a substrate for(More)
1. The effect of okadaic acid, a potent inhibitor of protein phosphatases 1 and 2A (PP1 and PP2A), on human platelets has been investigated. 2. Okadaic acid exerts a general increase in phosphorylation of platelet proteins but did not induce aggregation or secretion of 5-hydroxytryptamine (5-HT). Okadaic acid, however, did inhibit thrombin-induced(More)
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