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Biomedical subjects

R Horton

Publications and source records attributed to R Horton.

At least 379 records · Page 21Linked to original sources
PubMed1969

Conversion of blood androgens to estrogens in normal adult men and women.

Continuous infusions of Delta(4)-androstenedione-7-(3)H and testosterone-7-(3)H have been used to demonstrate that these androgens are converted to estrone and 17beta-estradiol, and contribute to the circulating blood levels of these estrogens in normal males and females. The conversion ratio (ratio of concentrations of radioactivity of free product steroid [chi(-PRO)] and free precursor steroid [chi(-PRE)], both corrected for recoveries, after an infusion of radioactive precursor steroid) for androstenedione (precursor) to estrone (product) is 0.013 in males and 0.007 in females, and the conversion ratio for testosterone (precursor) to estradiol (product) is 0.0018 in males and 0.005 in females. The transfer constant, [rho](BB) (AE1), for androstenedione conversion to estrone ([rho](BB) (AE1) = per cent of infused androstenedione, precursor, converted to estrone, product, when infusion and measurement are both in blood) is 1.35% in males and 0.74% in females, and the transfer constant, [rho](BB) (TE2), for testosterone conversion to estradiol is 0.39% in males and 0.15% in females. Whether measured as conversion ratio or transfer constant, the peripheral aromatization of androstenedione takes place to a greater degree than that of testosterone, and, for the respective androgens, both the conversion ratio and [rho](BB) value are greater in males than females. For the androgen interconversions, [rho](BB) (AT) is 4.5% in males and 2.2% in females; [rho](BB) (TA) is 8.2% in males and 12.0% in females. Studies on the distribution coefficients (effective concentration in red cells/plasma) for precursor radioactivity were also made. In both males and females the distribution coefficient for androstenedione is 0.16-0.17 while that of testosterone is 0.01-0.03.

Adult↗
PubMed1967

Androstenedione and its conversion to plasma testosterone in congenital adrenal hyperplasia.

The plasma concentration, production rate, and conversion ratio of androstenedione and testosterone were studied in seven children with congenital adrenal hyperplasia (CAH) of the 21-hydroxylase type. Plasma androstenedione and testosterone measured by double isotope derivative assay and estimated blood production rates were manyfold increased in the untreated state, markedly suppressed with glucocorticoid, and increased after the administration of ACTH. The metabolic clearance rate when corrected for body size and the conversion ratio of androstenedione to testosterone were similar to previously determined values in normal adults. Consideration of the androgen concentrations and conversion ratios indicates that in children with CAH, 76% of the plasma testosterone in prepubertal females and 36% in males are derived from peripheral conversion of blood androstenedione. The calculated amount of testosterone unaccounted for by peripheral conversion is similar to normal prepubertal values. This approach indicates that virilization in these children results from increased levels of testosterone but that the major source in CAH of this potent androgen is androstenedione secreted by the adrenal cortex.

17-Ketosteroids↗
PubMed1967

Hirsutism and virilization.

In normal females, androstenedione from both the adrenal cortex and ovary, as a result of peripheral conversion, is the source of the majority of biologically active testosterone in the circulation. The control of the secretion of precursor steroid and androgenic hormone (testosterone) in females is not clear at this time. There are a number of possibilities to explain various types of hirsutism and virilization. The presence of true virilization indicates a significant disorder and requires complete investigation. The presence of increased amounts of 17-ketosteroids in the urine implicates the adrenal cortex as a source of the pathologic manifestations. The suppressibility of elevated 17-ketosteroids with cortisol analogues aids in distinguishing between adrenal hyperplasia and autonomous neoplasm of the adrenal cortex. By far the most common entity in this area is simple hirsutism without virilization. Although our knowledge of this disorder is quite incomplete, conservative management is indicated. Further progress in this field is rapidly occurring. An informed clinician can do an adequate job of diagnosis and treatment with the clinical and laboratory tools generally available.

Androgens↗
PubMed1966

Cervico-vaginal smears. Cytologic examination.

Discrepancies among classification systems of Papanicolaou smears and lack of communication between cytologist and clinician are not uncommon. An attempt should be made by the cytologist to estimate, on a percentage scale, the likelihood of any given smear indicating carcinoma. This enables a more realistic and systematic management of a patient whose smear is other than negative. Proper technique in obtaining the smear is essential to proper interpretation, and it must be stressed that a negative smear in a patient with a cervical lesion does not rule out carcinoma. Likewise, a negative smear cannot rule out carcinoma higher in the generative tract.

Female↗