Richard H. Selinfreund

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Nervous system development involves a coordinated series of events, including regulation of cell proliferation and differentiation by specific extracellular factors. S100 beta is a neurotrophic protein that has been implicated in regulation of cellular proliferation, but direct evidence was lacking. In this report, nanomolar concentrations of S100 beta are(More)
A rapid method for the purification of plasma membrane from a relatively small number of A431 cells is described. The method is a simple, two-step differential centrifugation in the presence of Ca2+ that requires a total centrifugation time of 7 min. The membrane preparations contained a high level of epidermal growth factor (EGF) receptor activity(More)
The role of growth factors in the adult brain is largely unknown, although receptors for factors such as insulin-like growth factor-I (IGF-I) have been localized on nondividing mature neurons. Because neurons use the frequency and pattern of action potentials to encode information, we assessed the ability of IGF-I to modulate rapidly the electrical(More)
The phenotypic effects of selectively decreasing the levels of S100B in cultured glial cells were analyzed. Two separate antisense approaches were utilized for inhibition of S100/3 production: analysis of clonal isolates of rat C6 glioma cells containing an S100B antisense gene under the control of a dexamethasone-inducible promoter, and analysis of C6(More)
The phenotypic effects of selectively decreasing the levels of S100 beta in cultured glial cells were analyzed. Two separate antisense approaches were utilized for inhibition of S100 beta production: analysis of clonal isolates of rat C6 glioma cells containing an S100 beta antisense gene under the control of a dexamethasone-inducible promoter, and analysis(More)
The cell membrane isolation procedure we developed here can be scaled up from four to several hundred plates of cultured cells. Transmission electron microscopy, membrane marker enzyme analysis, binding study, EGF-dependent receptor autophosphorylation, and Western blots all demonstrate the biological activity of the purified cell membranes. The membrane(More)
Chlorpromazine (CPZ) or the functionally related N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide caused a rapid decrease in binding of 125I-epidermal growth factor (EGF) that was due to a specific decrease in receptor affinity. The decrease in ligand binding was observed when cells were exposed to CPZ at either 4 degrees C or 37 degrees C but a rapid(More)
We have devised a rapid and simple protocol for the purification of the plasma membrane from several lines of transformed cultured cells. A431 or KB plasmalemma was purified in 90 min with a two-step centrifugation cycle after selectively inducing microsomal aggregation by the addition of calcium to homogenized cells. Relative specific activity analysis(More)
The addition of medium containing 0.1% serum and 12-O-tetradecanoylphorbol-13-acetate (TPA) to quiescent cultures of BALB/c-3T3 cells caused a rapid decrease in the subsequent binding and accumulation of epidermal growth factor (EGF) during a 30-min exposure at 37 degrees C. With further incubation in medium containing TPA, the rate of EGF accumulation(More)
We have developed a novel Western blot procedure for the detection of epidermal growth factor (EGF) receptors within a complex mixture of membrane proteins. Purified cell membranes from either human placenta or cultured A431 cells were solubilized, resolved by electrophoresis, and electroblotted onto nitrocellulose paper. With 5-15% gradient gels,(More)