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R P Shearman

Publications and source records attributed to R P Shearman.

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Studies of human chorionic gonadotrophin, placental lactogen, and progesterone secretion in vitro.

The relative ability of explants of villous tissue from 8- to 10-week placenta to synthesize and release human chorionic gonadotrophin (HCG), human placental lactogen (HPL) and progesterone in culture was investigated. It was found that the synthesis and release of all three hormones was two to four times greater than the initial tissue content in the first 24 hours in culture. Between 24 and 48 hours of the secretion of HCG, HPL and progesterone was reduced to about 40 per cent, 20 per cent and 60 per cent respectively of that produced in the previous 24 hours. These results support previous findings that the production of HPL is more labile than HCG in culture, and suggest that progesterone secretion under the present conditions is least affected. When azastene (4, 4, 17 alpha-trimethylandrost-5-eno (2,3-d) isoxazol-17-ol), an inhibitor of gonadal and placental 3 beta-hydroxy steroid dehydrogenase conversion of pregnenolone to progesterone in rhesus monkeys, was added to the culture medium at a concentration of 0.3-150 mumol/l, no marked effect on the secretion of progesterone was observed. This indicates that the dehydrogenase in human placental tissue is either less accessible to azastene or that the inhibitory activity in the rhesus monkey was due to a metabolite of azastene.

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