Simultaneous measurement of cortisol, cortisone, and prednisolone is described. A dichloromethane extract of plasma is separated and purified by partition thin-layer chromatography and assayed by competitive protein binding. Using 0.2 ml of plasma, we could assay about 1 µg of these three steroids per 100 ml. We measured plasma corticosteroids in men on prednisone therapy, during ACTH stimulation, and in pregnant women at the time of delivery, and also in arterial and venous blood samples collected from the umbilical cord. Plasma concentrations of prednisolone (4.46 ± 1.07 µg/100 ml) were maximal 2 h after oral administration of prednisone (10 mg). Basal concentrations of cortisol and cortisone in these subjects were 10.50 ± 1.04 and 1.88 ± 0.69 (SD) µg/100 ml, respectively. The values decreased to less than 1 µg/100 ml 4 h after administration and returned to 12.82 ± 1.92 and 2.16 ± 0.49 µg/100 ml, respectively, by 24 h. After intramuscular injection of synthetic ACTH, values for cortisol and cortisone were maximal at 30 min, declining to pre-injection concentrations within 4 h. Plasma cortisol and cortisone values for maternal venous blood at delivery were 47.0 ± 8.5 and 7.1 ± 2.2, umbilical vein blood 4.9 ± 2.6 and 19.7 ± 2.8 and in blood from the umbilical arteries 7.3 ± 4.5 and 11.6 ± 4.9 µg/ 100 ml, respectively. Cortisol was higher (P < 0.05) in the umbilical arteries, cortisone (P < 0.01) in the umbilical vein.
A RIA for 2-hydroxyestrone (2-OHE1) in rat plasma has been developed. The assay employs an antiserum that is specific for catechol estrogens. Specificity is further ensured by purification of plasma extracts on Sephadex LH-20 columns before RIA. Blood was collected at 0 C in the presence of ascorbic acid to prevent oxidation. Under these conditions, the conversion of 2-OHE1 to methylated derivatives was found to be negligible. Plasma 2-OHE1, LH, FSH, PRL, estradiol, and progesterone were measured at 3-h intervals throughout the 4-day estrous cycle of the rat. The 2-OHE1 concentration varied from undetectable to 11 pg/ml plasma. No clearly defined relationship with the other hormones analyzed was observed. Thus, it is unlikely that changes in circulating 2-OHE1 levels are involved in the regulation of the gonadotropin surge and ovulation.
Summary High fat diets have been implicated in incidence of colon cancer both in epidemiological and animal studies. Present investigation deals with the incidence, location and numbers of large and small bowel tumours induced by 1,2-dimethyl hydrazine (DMH) in rats fed high fat diets and neomycin. Neomycin was used to modify the faecal sterol metabolism and the relationship of the high fat diet and faecal neutral and acid sterols to the large bowel tumorigenesis was evaluated. DMH administered rats were fed with (a) 20% safflower oil; (b) 20% safflower oil and neomycin; (c) 20% safflower oil, cholesterol and cholic acid; and (d) 20% safflower oil, cholesterol, cholic acid and neomycin. Neomycin was found to be associated with both increase and decrease of tumour numbers. The faecal sterols lithocholic and deoxycholic acids were found to have no participation, while cholesterol and cholic acid were found to decrease with increase in tumour numbers. However, faecal coprostanol has been found to have a significant positive correlation with tumorigenesis in all dietary groups. Therefore coprostanol might possibly be associated with colon carcinogenesis in DMH-fed rats and cholesterol metabolism in gut appears to be related to the development of tumours.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.