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Insulin-like growth factor-I (IGF-I) in concentration as low as 10 ng/ml significantly increased basal testosterone formation and 100 ng/ml of IGF-I increased testosterone production more than two fold in primary cultures of purified mature Leydig cells. IGF-I also markedly potentiated hCG-induced testosterone formation in a dose-dependent manner.(More)
The effects of human chorionic gonadotropin (hCG) on type I insulin-like growth factor (IGF) receptors of purified Leydig cells were investigated. Sprague-Dawley rats (50 day-old) were treated with a single injection of hCG 10 units intraperitoneally, type I IGF receptors were then determined daily for 4 days. HCG caused a rapid increase in type I IGF(More)
BACKGROUND Epidemiological reports suggest that Asians consuming a diet high in soy have a low incidence of prostate cancer. In animal models, soy and genistein have been demonstrated to suppress the development of prostate cancer. In this study, we investigate the mechanism of action, bioavailability, and potential for toxicity of dietary genistein in a(More)
To better define the biologic function of the type II insulin-like growth factor (IGF) receptor, we raised a blocking antiserum in a rabbit by immunizing with highly purified rat type II IGF receptor. On immunoblots of crude type II receptor preparations, only bands corresponding to the type II IGF receptor were seen with IgG 3637, indicating that the(More)
Characterization of insulin and type I insulin-like growth factor (IGF-I) receptors and the effects of insulin and IGF-I on steroidogenesis were evaluated by using purified adult Leydig cells from Sprague-Dawley rats. Purified Leydig cells were found to contain both high and low affinity binding sites for insulin, with Ka values of 1.08 X 10(9) and 1.1 X(More)
Genomic methylation, which influences many cellular processes such as gene expression and chromatin organization, generally declines with cellular senescence although some genes undergo paradoxical hypermethylation during cellular aging and immortalization. To explore potential mechanisms for this process, we analyzed the methylating activity of three DNA(More)
Defined factors regulating or influencing mammalian ventricular myocyte (cardiomyocyte) development are not known at this time. During early neonatal ventricular growth, cardiomyocytes begin a 'transition phase' of development toward cellular maturation (hypertrophy) that entails terminal proliferation and cellular binucleation. Insulin-like growth factor-I(More)
Purified preparations of renal glomeruli and tubules were obtained by a procedure involving perfusion of rat kidneys with magnetic iron oxide particles to selectively separate the iron-containing glomeruli from the nonmagnetic tubules. Detergent-soluble extracts of both renal glomerular and tubular membranes showed high-affinity, specific binding of(More)
Rat renal glomeruli were isolated by a technique involving kidney perfusion with a solution containing magnetic iron oxide particles, followed by homogenization, sieving, and concentration over a strong magnet. Isolated glomeruli were treated with 1% Triton X-100 to solubilize plasma membrane components, while insoluble basement membrane components were(More)
We investigated whether exposure of rats to sublethal hyperoxia (85% O2 for 7 days) raises the levels of proteins antigenically related to Na+ channels in alveolar type II (ATII) cells and, if so, whether this rise was accompanied by an increase in conductive Na+ transport in vitro. ATII cells were isolated from the lungs of these rats at the end of the(More)