We have characterized and purified the bile salt hydrolase from Lactobacillus sp. strain 100-100. Bile salt hydrolase from cells of the strain was purified with column and high-performance liquid chromatography. The activity was assayed in whole cells and cell-free extracts with either a radiochemical assay involving ['4C]taurocholic acid or a nonradioactive assay involving trinitrobenzene sulfonate. The activity was detectable only in stationary-phase cells. Within 20 min after conjugated bile acids were added to stationary-phase cultures of strain 100-100, the activity in whole cells increased to levels three-to fivefold higher than in cells from cultures grown in medium free of bile salts. In cell-free extracts, however, the activity was about equal, 1.41 and 1.53 ,umol/min per mg of protein, respectively, whether or not the cells have been grown with bile salts present. When supernatant solutions from cultures grown in medium containing taurocholic acid were used to suspend cells grown in medium free of the bile salt, the bile salt hydrolase activity detected in whole cells increased two-to threefold. Two forms of the hydrolase were purified from the cells and designated hydrolases A and B. They eluted from anion-exchange high-performance liquid chromatography in two sets of fractions, A at 0.15 M NaCl and B at 0.18 M NaCl. Their apparent molecular weights in nondenaturing polyacrylamide gel electrophoresis were 115,000 and 105,000, respectively. However, discrepancies existed in the apparent molecular weights and number of peptides detected in sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the two forms. Both had similar substrate specificities, highest on taurodeoxycholic and glycocholic acid, and pH optima between 3.8 and 4.5. The kinetic properties were also similar, with Vmaxs of 17 and 53 ,Lmol/min per mg of protein and Kms of 0.76 and 0.95 mM taurocholic acid for A and B, respectively.

No abstract

Neuroprotective effects of estradiol are well characterized in animal experimental models. However, in humans, the outcome of estrogen treatment for cognitive function and neurological diseases is very controversial. Selective estrogen receptor modulators (SERMs) may represent an alternative to estrogen for the treatment or the prevention of neurodegenerative disorders. SERMs interact with the estrogen receptors and have tissue-specific effects distinct from those of estradiol, acting as estrogen agonists in some tissues and as antagonists in others. In this study we have assessed the effect of tamoxifen, raloxifene, lasofoxifene (CP-336,156), bazedoxifene (TSE-424), and 17beta-estradiol on the hippocampus of adult ovariectomized rats, after the administration of the excitotoxin kainic acid. Administration of kainic acid induced the expression of vimentin in reactive astroglia and a significant neuronal loss in the hilus. SERMs did not affect vimentin immunoreactivity in the hilus, while 17beta-estradiol significantly reduced the surface density of vimentin immunoreactive profiles. Estradiol, tamoxifen (0.4-2 mg/kg), raloxifene (0.4-2 mg/kg), and bazedoxifene (2 mg/kg) prevented neuronal loss in the hilus after the administration of kainic acid. Lasofoxifene (0.4-2 mg/kg) was not neuroprotective. These findings indicate that SERMs present different dose-dependent neuroprotective effects. Furthermore, the mechanisms of neuroprotection by SERMs and estradiol are not identical, because SERMs do not significantly affect reactive gliosis while neuroprotection by estradiol is associated with a strong down-regulation of reactive astroglia.

Estrogens protect against cardiovascular disease in women through effects on the vascular wall and liver. Here we further characterize the rat as a model for the evaluation of estrogenic effects on plasma lipid levels vs. uterine wet weight. In adult ovariectomized female rats treated for 4 days s.c., 17alpha-ethinyl estradiol (EE) was the most potent agent to lower plasma total and high density lipoprotein cholesterol levels, followed by 17beta-estradiol and 17alpha-estradiol. However, 17alpha-estradiol had the greatest separation of uterotropic vs. cholesterol-lowering effects. EE had the same lipid-lowering potency whether administered s.c. or orally to adult rats. It had no effect on cholesterol levels in immature rats, even though the uterotropic response was dramatic. Testosterone propionate, dexamethasone, and progesterone did not significantly lower cholesterol levels. The antiestrogens tamoxifen and raloxifene lowered cholesterol levels, but with less efficacy and potency than the estrogens. ICI 182780 had no effect on cholesterol levels. When coadministered with EE, ICI 182780 inhibited the cholesterol-lowering and uterotropic activities of EE, suggesting that the estrogen receptor pathway is involved. In conclusion, although the information from the rat is limited as a model of the low density lipoprotein-lowering effects of estrogens in humans, it can be used to study the effects and mechanism of action of estrogen and antiestrogens on plasma cholesterol levels.

Novel 6-aryl-1,4-dihydro-benzo[d][1,3]oxazin-2-ones were synthesized and tested as progesterone receptor (PR) antagonists. These compounds were potent and showed good selectivity for PR over other steroid receptors such as the glucocorticoid and androgen receptors (e.g., greater than 80-fold selectivity at PR for 4h). Numerous 6-aryl benzoxazinones (e.g., 4h-j) were active orally in the uterine decidualization and component C3 assays in the rats. In these in vivo models,4h had potencies comparable to mifepristone.