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Biomedical subjects

D W Hahn

Publications and source records attributed to D W Hahn.

At least 73 records · Page 4Linked to original sources
PubMed1980

Studies on the mechanism of the antifertility activity of human chorionic gonadotropin in rodents.

Administration of 2.0 IU (3300 IU/mg) Human Chorionic Gonadotropin (hCG) to rats on days 7 to 13 or pregnancy induced complete embryonic resorption. This commercial preparation was also active in the mouse and hamster at 20 and 50 IUs per animal per day, respectively. It was inactive in the rat when administered after day 13 of pregnancy. Studies to determine how hCG could exert this effect resulted in the following findings: Concomitant administration of progesterone (8 mg/rat) to ovariectomized pregnant rats reduced the antifertility activity of hCG. Little or no estrogen could be identified by radioimmunoassay in the hCG preparations which had antifertility activity. The antifertility activity was, however, found associated with a molecular fraction which could be destroyed by both boiling and treatment with pronase, and which cross-reacted with anti-hCG. The antifertility activity of hCG was abolished by anti-hCG. Finally, serum estrogen levels in pregnant rats were found to be elevated by treatment with hCG.

Animals↗
PubMed1978

Intravas device studies in rabbits: II. Effects on sperm output, fertility and histology of the reproductive tract.

Solid (rod) and open (tube) prototype gole-platinum intravas device housings of three different surface designs were surgically inserted into the vasa deferentia of rabbits to test the feasibility of controlling male fertility. The devices were inserted through a short longitudinal slit in each vas deferens, secured with 4-0 silk suture and remained in situ for various periods ranging from 56--426 days. The solid devices completely inhibited the fertility of 6 rabbits in 20 of 21 matings. The fertile mating resulted after the loss of a device in one animal. In contrast, 7 of 9 rabbits receiving identical, but open (i.d. 0.8 mm), devices were fertile in numerous matings. Reduced sperm numbers or sperm-free ejaculates were usually obtained for 2--3 weeks after surgery, but returned to normal following this period. However, sperm blockage due to connective tissue infiltration and eventual encapsulation of the open devices was subsequently observed in about 50% of the animals. Histological changes of the vas deferens at the sites of some of the devices included occasional sperm granulomas, mild focal submucosal edema, mucosal erosion and mild mucosal hyperplasia due to fibroblastic proliferation.

Animals↗
PubMed1977

Contragestational agents. 1. Steroidal O-aryloximes.

The preparation of a series of O-aryloximes of various steroids by two different routes is described. These compounds were prepared by reacting a keto steroid with a substituted O-arylhydroxylamine in the presence of an acid catalyst or, alternatively, by the reaction of a steroidal oxime with a substituted aryl halide in the presence of a suitable base. These compounds were examined for their ability to interrupt postimplantive gestation in female rats. The most significant contragestational activity was seen with compounds in which the basic steroid structure was a 5alpha-androstane and the 3-oxime was of the p-nitrophenyl series. One of the most active compounds in the series (16) was shown to have the ability to terminate pregnancy, when orally administered to rats at 2.5 mg/kg on days 9-12 of gestation. This compound was found to be devoid of androgenic activity at this dose level.

Animals↗
PubMed1976

Changes in the sensitivity of adrenergic receptors in the oviduct during early gestation in the rabbit.

There is evidence to indicate that the transport of an egg through the rabbit oviduct is controlled through an interaction of the sympathetic nervous system and ovarian hormones. The effect of norepinephrine (NE) on the contractility of the oviduct during the first 8 days of gestation was studied using the rabbit perfused oviduct. The sensitivity of the alpha-adrenergic receptors of the oviduct to NE decreased progressively during early gestation. This was reflected in a potency change and a decrease in the maximal response obtained. These data support the concept that an isthmic sphinctering effect mediated by the autonomic nervous system may play a role in the regulation of egg transport through the oviduct. Blood pressure responses to NE did not change during early pregnancy except that the responses to NE were significantly enhanced immediately after mating. This suggests that the sensitivity changes to autonomic agents during early gestation may be selective for reproductive tissues.

Animals↗
PubMed1975

17alpha-Ethyl-20alpha-and -20beta-dihydroprogesterones and other 17alpha-ethyl-substituted pregnanes as potential contragestational agents.

The 17alpha-ethyl-substituted analogs of the two epimeric 20-dihydroprogesterones, allopregnadedione and pregn-5-ene-3,20-dione, were synthesized and evaluated for their possible oral contragestational (postcoital antifertility) activity in the rat. The compounds, though bound strongly to the progesterone receptor in vitro, were inactive preimplantively at 10 mg/kg and postimplantively at 40 mg/kg in vivo.

20-alpha-Dihydroprogesterone↗