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Biomedical subjects

H Horn

Publications and source records attributed to H Horn.

At least 91 records · Page 5Linked to original sources
PubMed1977

21-Hydroxylation of C-11-oxygenated and C-11-deoxysteroids by perfused dog adrenals.

The left adrenal of two female dogs were perfused with either 3 muCi [4-14C]cpd. S (2) and 45 muCi [1, 2-3H] 21-deoxycortisone (Dog I), or with 1 muCi [4-14C] 17-hydroxyprogesterone and 65 muCi [1,2-3H] 21-deoxycortisone (Dog II). In Dog I, 40% of the perfused 21-deoxycortisone was converted to cortisone and 23% of cpd. S was converted to cortisol. In Dog II the percent conversion of 21-deoxycortisone to cortisone and of 17- hydroxyprogesterone to cortisol was 24% and 15% respectively. The results demonstrate that the dog adrenal has the capability of hydroxylating an 11-oxygenated steroid at C-21.

Adrenal Glands↗
PubMed1977

Single versus fractionated doses of X-radiation and their effect on mammary carcinoma in the rat.

Selective destruction of neoplastic tissue by X-radiation, delivered as a single pulse or as a series of fractions, was investigated in transplanted DMBA-induced rat mammary tumors. Dosage was based on Strandqvist's fractionation curve, and compared with nominal standard doses. Tumor growth was most effectively inhibited when radiation was divided into three fractions. These results are consistent with predictions based on the NSD formula, rather than with the expected isoeffect of Strandqvist's curve. The higher doses of the three fractions were significantly more effective.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

Steroid C-21-hydroxylation by dog adrenal microsomes.

1,2-3H121-Deoxycortisol (1) 1,2-3H21-deoxycortisone and 1,2-3H-17OH-progesterone were incubated separately with dog adrenal microsomes. With substrates concentrations of 30 and 150 nmoles all the substrates were hydroxylated at C-21 to a similar extent. This result suggests that 21-deoxycortisol could be an intermediate in the biosynthesis of cortisol provided it is avilable in vivo.

Adrenal Glands↗
PubMed1976

Preparation of 1,2-3H-21-deoxycortisol by incubation of 1,2-3H-17-hydroxyprogesterone with rat adrenal mitochondria.

A method is described for preparation of 1,2-3H-21-deoxycortisol by incubation of 1,2-3H-17-hydroxyprogesterone with rat adrenal mitoochondria. The radiochemical purity of the product was established by two subsequent chromatographies, reversed isotopic dilution and oxidation to 21-deoxycortisone. The final yield of 1,2-3H-21-deoxycortisol was approximately 15%.

17-Hydroxycorticosteroids↗
PubMed1976

Anti-tumour efficacy of calusterone against DMBA-induced rat mammary adenocarcinoma in vivo and in organ culture.

The effect of calusterone (7beta,17alpha-dimethyltestosterone) on rat mammary DMBA-induced adenocarcinoma was studied both in vivo and in organ culture. In vivo all 8 tumours with a diameter of less than 30 mm regressed following calusterone injection (10 mg/day for 2-3 weeks). In organ culture calusterone (20 mug/ml medium) inhibited the synthesis of DNA and RNA in all 7 cases examined. Testosterone also inhibited the synthesis of DNA and RNA in organ culture in 12 out of 14 and 10 out of 14 tumours respectively. Oestradiol-17beta on the other hand had no effect on DNA and RNA synthesis in organ culture although 70% of the tumours examined were ovarian dependent, i.e. regressed following castration. This could be explained by the direct effect of calusterone on rat adenocarcinoma compared with the indirect effect of oestradiol-17beta which probably exerts its action by activating the secretion of prolactin which acts on the tumour.

9,10-Dimethyl-1,2-benzanthracene↗