Radioimmunoassay of plasma testosterone, with use of polyethylene glycol to separate antibody-bound and free hormone

We have developed a reliable radioimmunoassay for testosterone in plasma, polyethylene glycol ("Carbowax 6000") being used to separate antibody-bound and free hormone. Testosteron is separated from interfering steroids, notably dihydrotestosterone, by liquid-liquid partition chromatography on infusorial earth (Celite). The assay is sensitive (9 pg for standards), precise, and accurate. The lowest measurable concentration fo testosterone is 350 ng/liter for plasma from men and 70 ng/liter for plasma from women. Intra- and inter-assay coefficients of variation were 6.9% and 9.7%, respectively, for plasma from men, and 9.6% and 11.8%, respectively, for plasma from women. Our method for separating antibody-bound and free hormone is practical and convenient and may be generally applicable to all radioimmunoassays of steroid hormones in plasma.

Enzymatic oxidation and reduction of C19-delta5-3beta-hydroxysteroids by hepatic microsomes. IV. Induction of DHA hydroxylases and aminopyrine N-demethylase in immature male rats by androgens

The capacities of various C19 steroids for prematurely inducing the normal metabolic patterns of rat liver in adulthood (70 days old) have been studied with hepatic microsomes of 42-day-old males castrated on day 24, 30, 32, or 34 of life. Dehydroepiandrosterone 16alpha-hydroxylase activity was significantly reduced (P less than 0.05) by castration during this 10-day interval but the 7alpha- and 7beta-hydroxylases, the N-demethylation of aminopyrine, and cytochrome P-450 concentration were unaffected. Daily administration of testosterone stimulated the DHA 16-alpha- and 17beta-hydroxylases, aminopyrine N-demethylation, and increased the P-450 content, but suppressed the 7alpha-hydroxylase. These effects only appeared with more than 1 week of the continuous treatment. Testosterone was the most active of the androgens studied; dihydrotestosterone (DHT) increased the DHA 16alpha-hydroxylase to a lesser extent, but this steroid and etiocholanolone stimulated DHA 7alpha-hydroxylation; androsterone was totally ineffective. These data suggest that testosterone rather than DHT from pubertal testes plays a significant role in control of hepatic oxidative enzyme activities during puberty.

Antitumor activity of amino acid derivatives in the primary screening

Approximately 350 amino acid derivatives were synthesized and tested for antitumor activity in four tumor systems. The effect on life prolongation and tumor growth was examined using mouse leukemia SR-61, Ehrlich ascites carcinoma, ascites sarcoma-180, and rat ascites hepatoma (AH-60C). Among these 350 derivatives, 29 compounds were found to be significantly effective in prolongation of the median life-span and inhibitory effect on tumor growth in the primary screening. Among these 29 compounds, the following five compounds were found to possess potential antitumor activity: N-(2-Naphthalene)sulfonyl-DL-tryptophan (A-91), 2-naphthylaminomethyl-gamma-aminobutyric acid (A-144), N-ethylcarbaminomethyl-L-isoleucine (A-145), N-9-fluorenylacetyl-L-phenylalanine (A-192), and N-propionyl-L-valine (A-195). These five compounds were active in prolongation of the life-span of mice bearing Ehrlich ascites carcinoma and in the inhibition of the cell growth. Some of these amino acid derivatives inhibited biosynthesis of macromolecules, DNA, RNA, and protein, in tumor cells. These results suggest that the site of action of the five amino acid derivatives appears to result from the inhibition of macromolecules and another unknown mechanism.