Occurrence of thrombocytopenia in psychiatric patients taking valproate.

OBJECTIVE: Few studies, with conflicting results, have examined the occurrence of thrombocytopenia with valproate administration. This study assessed whether the platelet-lowering effects of valproate are increased among elderly psychiatric patients. METHOD: The charts of 39 psychiatric inpatients taking valproate were reviewed. Information on hematologic function and on doses and serum levels of valproate at sequential intervals over a 12-month period was abstracted. Data for subjects age <60 years (nonelderly subjects) and those age >/=60 years (elderly subjects) were compared. RESULTS: More than half (53.8%) of the elderly patients but only 13.0% of the nonelderly patients had at least one episode of thrombocytopenia. This difference corresponded to a significantly greater lowering of platelet counts among elderly patients than among nonelderly patients. CONCLUSIONS: The high rate of thrombocytopenia in our study suggests the need for routine monitoring of platelet counts among patients taking valproate, particularly among elderly patients.

Expression of embryonic myosin heavy chain mRNA in stretched adult chicken skeletal muscle.

Chronic stretch of the chicken fast-twitch patagialis muscle increases the rate of growth and percentage of fast-twitch oxidative fibers. We have analyzed the effects of stretch on the expression of two previously identified "embryonic" myosin heavy chain (MHC) mRNAs (p251 and p110). Both MHC mRNAs were expressed in the patagialis at their highest levels in the embryo and 1 wk after hatching. During posthatch development (7-52 wk), the p110 mRNA was expressed in only trace quantities while the p251 mRNA was not detectable. After 2 wk of stretch of the patagialis in 7- or 38-wk-old birds, the p110 mRNA was increased to levels similar to that found in patagialis of newly hatched chicks, whereas expression of the p251 transcript was not affected. The existence of two other MHC mRNAs homologous to the p110 mRNA was suggested by the S1 mapping analysis, one of which was expressed at dramatically reduced levels in the stretched patagialis. It is concluded that stretch can cause selective alterations in the expression of developmentally regulated MHC isoforms in chicken fast-twitch muscle.