We have examined the effect of physiologic concentrations of dexamethasone on the induction of differentiation of the human promyelocytic leukemia cells (HL-60) and the activity of surface receptors for the f-met-leu-phe chemotactic peptide. Dexamethasone at a concentration of 500 nM was markedly synergistic with dimethylformamide and dimethylsulfoxide, but not with trans-retinoic acid, in indu...

Sixteen steroids with different endocrine activities were administered to female rats for 6 or 7 days, in a broad range of doses. Liver growth was recorded by measuring weight and DNA contents and monooxygenase activity by assaying the turnover of five different substrates. According to their effects on these parameters steroids were assigned into one of the following three groups: (a) Estrogen...

Vitellogenin (Vtg), the precursor molecule for yolk, is synthesized in the liver under estrogenic control. In all oviparous species, including fish, the process of vitellogenesis is crucial to subsequent embryonic development. This study attempted to obtain the cDNA encoding for Vtg from female Japanese eels, Anguilla japonica. Rapid amplification of cDNA ends (RACE) and polymerase chain reacti...

The synthetic hormone, 17-α-methyltestosterone (MT), is used in fish hatcheries to induce male monosex. Androgenic effects on various fish species have been reported; however, few studies have assessed possible genotoxic effects, although there are concerns about such effects in target and non-target species. We evaluated genotoxic and gonadal effects of MT in adult tilapia (Oreochromis nilotic...

The central role of testosterone in the development of male characteristics, as well as its beneficial effects on physical performance and muscle growth, has led to the search for synthetic alternatives with improved pharmacological profiles. Hundreds of steroidal analogs have been prepared with a superior oral bioavailability, which should also possess reduced undesirable effects. However, onl...

In previous papers (1, 2), it has been reported that in male rats the administration of morphine and also starvation caused a marked decrease in the activities of drug-metabolizing enzymes of liver microsomes for hexobarbital hydroxylation and aminopyrine N-demethyl ation, but this was not the case in female rats. On the other hand, the activities of drug metabolizing enzymes for aniline hydrox...

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of the egg yolk precursor vitellogenin (VTG) in the liver of medaka (Oryzias latipes) and was employed to establish an in vivo testing system for estrogen and estrogenic compounds using liver homogenates. Results of 3-month-old fish exposed to three reference chemicals (ethynylestradiol, methyltestosterone and flutamid...

This study aimed to develop sex reversal procedures targeting the embryonic period as tools to study the early steps of sex differentiation in Nile tilapia with XX, XY, and YY sexual genotypes. XX eggs were exposed to masculinizing treatments with androgens (17α-methyltestosterone, 11-ketotestosterone) or aromatase inhibitor (Fadrozole), whereas XY and YY eggs were subjected to feminizing treat...

Both testosterone and cyclic GMP stimulate DNA synthesis. Because cyclic GMP and testosterone seem to have similar actions, the objective of this investigation was to determine if testosterone and its precursors might have part of their mechanism of action through stimulation of guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2], the enzyme that catalyzes the formation of cycli...

Epidemiological and psychophysiological data suggest that groups that differ in reproductive hormones and stress responses also differ in risk for cardiovascular disease. To evaluate the effects of hormone therapy on women's cardiovascular responses to laboratory stressors, 89 healthy postmenopausal women were tested twice, before and after exposure for about 8 weeks to one of the five conditio...