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We studied whether nerve growth factor (NGF) can affect the membrane potential and conductance of PC12 cells. We demonstrate that NGF depolarizes the membrane of PC12 cells within a minute and by using transfected NIH 3T3-Trk and -p75 cells we show that both the high affinity NGF receptor p140trk and the low affinity NGF receptor or p75NGF may be involved in the depolarization. Tyrosine kinase inhibitor, K252a, partially inhibited the depolarization, but two agents affecting intracellular calcium movements, Xestospongin C (XeC) and thapsigargin, did not. The early depolarization was eliminated in Na+ free solutions and under this condition, a prolonged (>2 min) hyperpolarization was observed in PC12 cells in response to NGF. This hyperpolarization was also induced in PC12 cells by epidermal growth factor (EGF). Voltage clamp experiments showed that NGF produced a late (>2 min) increase in membrane conductance. The Ca2+-dependent BK-type channel blocker, iberiotoxin, and the general Ca2+-dependent K+ channel blocker, TEA, attenuated or eliminated the hyperpolarization produced by NGF in sodium free media. Under pretreatment with the non-selective cation channel blockers La3+ and Gd3+, NGF hyperpolarized the membrane of PC12 cells. These results suggest that three different currents are implicated in rapid NGF-induced membrane voltage changes, namely an acutely activated Na+ current, Ca2+-dependent potassium currents and non-selective cation currents. Published 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Based on over 50,000 parental descriptors of children gathered in eight different countries, we used a combination of focus group sorting of descriptors in each country and factor analyses of instruments developed in four of the countries (United States, China, Greece, and the Netherlands) to describe children ages 3 to 12 years to select items for an instrument that would work well across countries to access personality. Through many factor analyses of indigenous items in each country, a core set of 141 items was used in three of the countries, with over 3000 parents responding to our instruments in China, Greece, and the United States. Much cross-comparative research analysis has resulted in 15 robust midlevel scales that describe the structures of parental descriptors that are common to the three countries. The data on the English (U.S.) sample are presented in detail. Links to temperament and behavior problems are presented and discussed. [ABSTRACT FROM AUTHOR]