Effect of apolipoprotein a-I complex with tetrahydrocortisone on protein biosynthesis and glucose absorption by rat hepatocytes.

We studied the effect of apolipoprotein A-I-tetrahydrocortisone complex on (14)C glucose absorption and lactate accumulation and on the rate of protein biosynthesis in isolated rat hepatocytes. The presence of apolipoprotein A-I-tetrahydrocortisone complex in the incubation medium increased absorption of labeled glucose by hepatocytes by 52%, while lactate content in the conditioning medium increased 4-fold. The rate of protein biosynthesis increased by 80% in comparison with control cells. It is hypothesized that the increase in protein biosynthesis rate in hepatocytes under the effect of apolipoprotein A-I-tetrahydrocortisone complex is due to stimulation of energy metabolism, specifically, of its glycolytic component.

Heparin-steroid conjugates lacking glucocorticoid or mineralocorticoid activities inhibit the proliferation of vascular endothelial cells.

A new class of angiogenesis inhibitors consist of a non-anticoagulating derivative of heparin, which binds to vascular endothelial cells, coupled to a steriod (e.g., cortisol) which suppresses endothelial cell division. We linked heparin to a further 10 steroids in an effort to identify ones which would yield more effective or safer angiogenesis inhibitors. Steroids having a C3 ketone group were linked by reaction with a hydrazide derivative of heparin. Steroids having a C20 ketone group and lacking a C3 ketone could not be prepared by this method, necessitating the development of alternative methods. The most efficient was to convert the steroid into a derivative having a hydrazone group at C20 and then link the steroid hydrazone to heparin. Conjugates prepared from steroids having C3 ketones were at most 6-fold more inhibitory than the free steroids to endothelial cells in tissue culture. In contrast, steroids having a C20 ketone but lacking a C3 ketone (tetrahydrocortisone, tetrahydrocortisol and tetrahydro S) became highly inhibitory to endothelial cells only after conjugation to heparin. They inhibited [3H]thymidine incorporation by 50% at a steroid concentration of 18-30 microM and by 95% at 300 microM. Since tetrahydrocortisone, tetrahydrocortisol and tetrahydro S lack glucocorticoid and mineralocorticoid activity, they may prove safer alternatives to cortisol for prolonged administration, as is likely to be necessary with anti-angiogenic therapies.

Estrogen can regulate the cell cycle in the early G1 phase of yeast by increasing the amount of adenylate cyclase mRNA.

The effects of beta-estradiol (estrogen; a minor component of yeast cells) on S. cerevisiae cells in the G0 and G1 phases were examined. Results showed that estrogen stimulated the recovery of growth from G0 arrest induced by nutrient limitation or ts mutation of cdc35 (adenylate cyclase) in the early G1 phase, and inhibited entry into the resting G0 phase by increasing the intracellular cAMP level. However, estrogen had no effect on late G1 arrest induced by the alpha factor or ts mutation of cdc36. Estrogen was found to lead to higher steady-state levels of adenylate cyclase mRNA but not to affect the expression of the RAS1 and RAS2 genes, although these can also alter the intracellular cAMP level. These results suggest that estrogen influences the cell cycle of yeast in the early G1 phase by controlling the level of cAMP through the increase of adenylate cyclase mRNA.

Effect of estradiol and steroid analogues on the clearance of immunoglobulin G-coated erythrocytes.

Although the disproportionate frequency of several immunologic disorders among women is well recognized, the effect of sex steroids on immunologic processes is unclear. We used an animal model, which has helped to elucidate the effect of corticosteroids in vivo, to quantitatively assess the effect of estradiol and steroid analogues on the immune clearance of IgG-coated erythrocytes. While corticosteroids impaired the clearance of IgG-coated erythrocytes, estradiol, in doses comparable to those achieved during pregnancy, significantly enhanced the clearance. Estradiol, however, did not enhance the splenic clearance of heat-altered erythrocytes. Splenic macrophages isolated from estradiol-treated animals expressed enhanced receptor affinity for the Fc portion of immunoglobulin G [Fc(IgG)], an effect probably responsible for the enhanced in vivo clearance. No consistent effect of estradiol on the splenic macrophage C3 receptors was observed. The synthetic androgen danazol, the mineralocorticoid deoxycorticosterone, and the cortisol metabolite tetrahydrocortisone did not alter the clearance of IgG-coated cells after 7 d of therapy. The estrogen antagonist/agonist tamoxifen enhanced the clearance of IgG-coated cells, but to a lesser extent than estradiol. An effect of estrogens on macrophage Fc (IgG) receptor-mediated clearance may explain in part the variation in clinical expression of several autoimmune disorders during changes in hormonal state, such as pregnancy.

The use of tetrahydrocortisone-3-beta-D-glucuronide in the measurement of urinary 17-hydroxycorticosteroids.

THE 3-G was added to H2O and 56 urines, and the recovered THE was measured by the Porter-Silber method. The recovery from H2O was quantitative (98 +/- 2%), but highly variables from urine, ranging from 35 to 100%. The necessity of the proper standard in analysis of urinary steroid glucuronides was demonstrated. The presence in urine of endogenous inhibitors to beta-glucuronidase was confirmed.