Tyrosine hydroxylase phosphorylation in bovine adrenal chromaffin cells: the role of intracellular Ca2+ in the histamine H1 receptor-stimulated phosphorylation of Ser8, Ser19, Ser31, and Ser40.

Tyrosine hydroxylase (TOH), the rate-limiting enzyme in catecholamine biosynthesis, is regulated by phosphorylation. Activation of histaminergic H1 receptors on cultured bovine adrenal chromaffin cells stimulated a rapid increase in TOH phosphorylation (within 5 s) that was sustained for at least 5 min. The initial increase in TOH phosphorylation (up to 1 min) was essentially unchanged by the removal of extracellular Ca2+. In contrast, the H1-mediated response was abolished by preloading the cells with BAPTA acetoxymethyl ester (50 microM) and significantly reduced by prior exposure to caffeine (10 mM for 10 min) to deplete intracellular Ca2+. Tryptic-phosphopeptide analysis by HPLC revealed that the H1 response in the presence or absence of extracellular Ca2+ resulted in a major increase in the phosphorylation of Ser19 with smaller increases in that of Ser40 and Ser31. In contrast, although a brief stimulation with nicotine (30 microM for 60 s) also resulted in a major increase in Ser19 phosphorylation, this response was abolished in the absence of extracellular Ca2+. These data indicate that the mobilization of intracellular Ca2+ plays a crucial role in supporting H1-mediated TOH phosphorylation and may thus have a potentially important role in regulating catecholamine synthesis.

Amoxicillin treatment of bacterial vaginosis during pregnancy.

The purpose of this investigation was to evaluate the efficacy of amoxicillin for treatment of bacterial vaginosis during pregnancy. The diagnosis of bacterial vaginosis was established by clinical examination and microscopic examination of a Gram stain and saline preparation of vaginal secretions. In a double-blind, randomized manner, 108 patients at 15-25 weeks' gestation were assigned to treatment with oral amoxicillin, 500 mg three times daily for 14 days, or placebo. Patients were evaluated 2 weeks after treatment, at 34-36 weeks' gestation, and at delivery. There were no significant differences between the two groups with respect to any clinical or microbiologic measure of treatment outcome. There were also no significant differences in the frequency of obstetric complications. We conclude that amoxicillin is not effective therapy for bacterial vaginosis in pregnant women.