Paul Knapstein

Metabolism of free and sulfoconjugated DHEA in brain tissue in vivo and in vitro.

Abstract Two rhesus monkey brains were perfused in vivo either with 14C-DHEA (dehydroepiandrosterone) and 3H-DHEA sulfate or with 3H-DHEA. Plasma from the jugular vein and the brain were analyzed for free and conjugated metabolites. Many more free than sulfoconjugated steroids were withdrawn from the blood. These were not stored to a large extent. Up to 16% of DHEA were metabolized to ring D hydroxylated Δ5-compounds. When fresh human fetal brain was incubated with 3H-DHEA, 5.9% of the free steroids were sulfurylated. 30% were converted mainly to ring D hydroxylated Δ5-metabolites.

Rapid quantitation of estrogens by diazotization and direct thin layer densitometry

Abstract Fast Violet Salt B (6-benzoylamino-4-methoxy-5-toluidine, diazonium salt) reacts with estrogens to form stable yellow compounds. These can be separated by thin layer chromatography and quantitated directly with a double beam spectrodensitometer. The method is sensitive enough to measure 0.05 μg steroid.

Rapid quantitation of 2,4-dinitrophenylhydrazones of plasma ketosteroids by thin layer densitometry.

Abstract A double beam absorbance spectrodensitometer is used for the quantitation of DHEA, androsterone and etiocholanolone from about 2 ml plasma. After solvolysis, purification and formation of the 2,4-dinitrophenylhydra-zone, DHEA can be estimated directly on the thin layer plate without elution. The proper determination of androsterone and etiocholanolone requires elution and rechromatography on a second plate. The whole procedure can be performed in an 8-hour workday.

Biosynthesis of steroid hormones in human gonads VI. in vivo perfusion of the testis with 1-14c-acetate and 7α-3h-cholesterol

Abstract 14 C-acetate (22.2 μg) and 3 H-cholesterol (0.39 μg) were injected into the spermatic artery of a 58-year-old man. In the following 45 min., 137.5 ml blood (64.5 ml plasma) were collected from the corresponding vein. Here 3 H/ 14 C-double labeled dehydroepiandrosterone (DHEA) and testosterone were isolated and identified by chromatography, by formation of the acetates and 2,4-dinitrophenylhydrazones and by crystallization with non-labeled standards. Venous cholesterol, purified by digitonin precipitation, bromination and crystallization with standard, contained only 3 H activity. The data suggested that the testis was able in vivo to synthesize steroid hormones de novo from acetate as well as from cholesterol. Significant amounts of 3 H and 14 C activity were found to be coupled with sulfuric acid.