Showing papers on "Steroid biosynthesis published in 1971"
TL;DR: Evidence is presented in support of the hypothesis that the principle acute effect of o,p′-DDD in the dog adrenal cortex is to inhibit an ACTH mediated step in steroidogenesis which occurs prior to pregnenolone formation.
56 citations
TL;DR: Observations made in vivo with an alga and with tissue cultures of an angiosperm indicate that lanosta-8,24-dien-3β-ol (lanosterol) and its 9,19-cyclo derivative (cycloartenol) are both acceptable precursors in the biosynthesis of the major sterols of photosynthetic organisms.
46 citations
TL;DR: It is concluded that the increasing production of estrogens in the second half of gestation arises from an increasingProduction of androgen sulfates by the fetal adrenal associated with progressive growth of and stimulation of steroid biosynthesis in this gland, which are provoked by an elevated secretion of ACTH from the fetal pituitary.
Abstract: Publisher Summary This chapter focuses on progressive increase in estrogen production in human pregnancy. Estrogens are synthesized in the placenta largely from androgen sulfates secreted by the fetal zone of the fetal adrenal. The level of supply of these precursors determines the quantity of estrogen produced. This chapter considers factors that modify the concentration of cortisol in the fetal circulation. These are discussed in terms of synthesis, metabolism, transport from the maternal system, and transport to the maternal system. It is concluded that the increasing production of estrogens in the second half of gestation arises from an increasing production of androgen sulfates by the fetal adrenal associated with progressive growth of and stimulation of steroid biosynthesis in this gland, which, in turn, are provoked by an elevated secretion of ACTH from the fetal pituitary. The secretion of ACTH in increased quantities is a response to an increased metabolic clearance rate of cortisol from the fetal plasma. A major factor concerned in the increased clearance of cortisol is the disparity in the number of available binding sites for cortisol in fetal and maternal plasma.
35 citations
TL;DR: The fine structure of corpora lutea from 14 white-tailed deer was studied from early through near-term pregnancy and appeared more active in steroid biosynthesis than the modified granulosal and thecal lutein cells.
Abstract: The fine structure of corpora lutea from 14 white-tailed deer was studied from early through near-term pregnancy. The corpora contained both thecal and granulosal lutein cells. The small, elongate and cylindrical thecal lutein cells contained many lipid droplets, juxtanuclear Golgi elements, abundant agranular endoplasmic reticulum, and other cytoplasmic organelles. These cells were observed throughout pregnancy. Some of the thecal lutein cells became modified during early to midpregnancy. The modified thecal lutein cells possessed many lipid droplets, several lysosomes, packets of PAS-positive glycogen granules, and numerous small membranous whorls of agranular endoplasmic reticulum. The granulosal lutein cells had highly folded and/or ruffled plasma membranes, abundant tortuous tubular and cisternal agranular endoplasmic reticulum, numerous rod-shaped to round mitochondria with tubular and lamellar cristae, Golgi elements, and a few packets of granular endoplasmic reticulum. Many granulosal lutein cells became modified during mid- to near-term pregnancy by the addition of numerous small membrane-bound osmiophilic droplets and variable numbers of large nonmembrane-bound lipid droplets. The granulosal and thecal lutein cells appeared more active in steroid biosynthesis than the modified granulosal and thecal lutein cells.
17 citations
TL;DR: It is suggested that the first crucial event in the pyridine nucleotide linked reduction is the activation of the substrate through protonation to give an electron deficient species which in the next step is neutralized by the addition of a hydride from NAD(P)H to furnish the product.
Abstract: The conversion of desmosterol into cholesterol was carried out in the presence of either tritiated water or [43H2]NADPH. The side chain fragment consisting of carbon atoms 23–27 of cholesterol was obtained through the combination of biological and chemical techniques. Selective degradation of the fragment led to the conclusion that in the saturation of the 24,25-double bond of desmosterol a hydrogen atom from the medium is added to C-24 and another from the 4-position of NADPH to C-25. These results in conjunction with similar studies previously reported on the saturation of other C═C in steroid biosynthesis are interpreted in terms of a general mechanism. It is suggested that the first crucial event in the pyridine nucleotide linked reduction is the activation of the substrate through protonation to give an electron deficient species which in the next step is neutralized by the addition of a hydride from NAD(P)H to furnish the product.
16 citations
TL;DR: In this paper, the results indicate that the in vitro transformation of these C 21 radioactive substrates by bullfrog interrenals is similar to that of avian and noncortisol-producing mammalian adrenal glands.
13 citations
TL;DR: Aminoglutethimide, an inhibitor of steroid biosynthesis, seems to have an extraglandular site of action on steroid catabolism, which may be responsible for a few signs of virilization and fetal masculinization in women taking AG.
Abstract: Aminoglutethimide (AG), an inhibitor of steroid biosynthesis, seems to have an extraglandular site of action on steroid catabolism. To study this effect, five males with peripheral hypogonadism were first given testosterone propionate and then the same dose was repeated combined with AG and urinary testosterone, and its metabolites were measured. AG was shown to have a very evident effect on the peripheral degradation of exogenous testosterone. This may be responsible for a few signs of virilization and fetal masculinization in women taking AG.
12 citations
TL;DR: Cholesterol-4-14C was not degraded into corticosteroids by surviving interrenal sections, whether it was emulsified in Tween 80 or not and regardless of the addition of ACTH or NADP plus G-6-P to the in vitro systems.
9 citations
TL;DR: Treatment of day 8 pregnant rats for 3 days with 30 mg aminoglutethimide, an inhibitor of steroid biosynthesis, did not affect gestation but when administered with as little as 0.1 μg of estradiol-17β, abortion occurred in 50% of the animals.
9 citations
TL;DR: Investigation of the conversion of pregnenolone-7α- 3 H to progesterone-3 H by immature and term placental villi supported in organ culture found that organ culture may prove valuable in further studies of placental steroid metabolism.
5 citations
TL;DR: The ability of the testes of rats deficient in essential fatty acids (EFA) to synthesize testosterone from labeled cholesterol was investigated in eviscerated animals and it seems unlikely that the degenerative changes in thetestes of EFA - deficient rats are due to a lack of androgens.
Abstract: The ability of the testes of rats deficient in essential fatty acids (EFA) to synthesize testosterone from labeled cholesterol was investigated in eviscerated animals. The data indicate that the testes of deficient rats were capable of synthesizing more testosterone than the control animals. It seems unlikely therefore that the degenerative changes in the testes of EFA - deficient rats are due to a lack of androgens. A significant increase (p < .005) in the biosynthesis of testosterone by the deficient testes is postulated to be due to changes in the physical structure of mitochondria. Mitochondria isolated from the deficient testes were found to have a different configuration than mitochondria from the normal animals. Mitochondria from deficient animals displayed a greater tendency to swell upon the addition of Ca++. The degeneration of the male reproductive organs despite the increased capacity for steroid biosynthesis in this deficiency may be due to decreased responsiveness of the target organs to cir...
Journal Article•
TL;DR: Distributed as a Mendelian recessive characteristic, familial Addison's disease of childhood may represent a milder form of the same genetic disorder responsible for congenital adrenal hypoplasia of infancy.
Abstract: Familial prepubertal Addison's disease is presented in two sets of brothers. Predominance of males with normal sex differentiation, lack of defects in steroid biosynthesis and absence of antibodies and associated endocrinopathies, separate this entity from other forms due to enzyme deficiencies or disordered cellular immune response. Distributed as a Mendelian recessive characteristic, familial Addison's disease of childhood may represent a milder form of the same genetic disorder responsible for congenital adrenal hypoplasia of infancy.
Journal Article•
TL;DR: This long acting progesterin acts by suppressing ovulation and the endometrium becomes hypoplastic, however it seems to exert a cortisol like effect possibly by suppressing ACTH secretion.
Abstract: Long acting "depo" progesterins require less-frequent intramuscular administration. The biochemical effects of medroxyprogesterone acetate (17alpha-hydroxy 6 alpha-methyl progesterone acetate) were evaluated with respect to liver function bone homeostasis adrenocortical function ovarian function amino acid excretion and carbohydrate metabolism in patients having received the steriod for at least 6 months. Standard biochemical assays were used: GLC methods for assay of pregnanediol and pregnanetriol fluorometry for estrogen determinations. Carbohydrate metabolism was evaluated by measuring plasma glucose serum insulin growth hormone triglycerides and free fatty acids after oral administration of 100 g of glucose. The results indicated no detectable cholestasis or abnormal serum levels of hepatocellular enzymes. No abnormality of bone homeostasis was found. Suppression of steroid biosynthesis in the adrenal cortex was inferred from a decrease in urinary excretion of 17-hydroxycorticosteroids and anovulatory state. Qualitatively urinary amino acids were essentially normal. The results of carbohydrate metabolism will be discussed. Biopsy specimens of endometrium were in keeping with an anovulatory state. This long acting progesterin acts by suppressing ovulation and the endometrium becomes hypoplastic. However it seems to exert a cortisol like effect possibly by suppressing ACTH secretion.(FULL TEXT)
01 Jan 1971
01 Jun 1971
TL;DR: Findings reveal possibilities for the enzymatic conversion of steroids which cannot be acetylated in their primary form to compounds which can be determined by the double isotope technique and a disturbance of steroid biosynthesis in the form of an inhibition of 11β hydroxylation.
Abstract: The effect of general damage to suprarenal gland cells on the bio-synthetic output of steroid hormones by the adrenal cortex was examined in rabbits and compared with the state of the energy metabolism. For this purpose the suprarenal glands were cut off from their blood supply for up to 120 min. Regarding the chief steroid of the suprarenal gland, corticosterone, the secretion at maximum ACTH stimulation was 17.89 nmol/min; this level dropped to 5.83 nmol/min after 60 min of ischemia and 30 min of recovery, and to 2.38 nmol/min after 120 min of ischemia and 30 min of recovery. A comparison of these findings with the other data revealed a disturbance of steroid biosynthesis in the form of an inhibition of 11β hydroxylation. Maximum ACTH efficiency at ACTH saturation is proportional to the time of damage; it can be expressed by the exponential equation ACTH-eff (max.)=17.9×exp (−0.0156×t) The meaning of the findings with regard to the mechanism of ACTH activity is discussed. In addition, possibilities are shown for the enzymatic conversion of steroids which cannot be acetylated in their primary form to compounds which can be determined by the double isotope technique.