No abstract available

[en] A simple procedure for the preparation of 21-³H- pregnenolone using pregnenolone as starting material is described. The procedure involved removal of the C-21-methyl group of the steroid and the side-chain was constructed with ³H-CH₃MgI in two steps: a Grignard reaction followed by oxidation of the resulting alcohol. An overall yield of 71% was achieved. (author)

No abstract available

[en] 26,26,26,27,27,27 Hexadeuterio cholesterol has been prepared in 9 steps from pregnenolone and hexadeuterio acetone with an overall yield of 7%. (author)

No abstract available

No abstract available

[en] From clinical experience it is known that medroxyprogesterone acetate (MPA) can increase the radiosensitivity of adenocarcinomas of the corpus uteri. This study investigates this phenomenon in vitro. Primary explants of highly differentiated adenocarcinomas were irradiated with or without pretreatment with MPA and compared with an untreated control group and to a group treated with MPA only. Cell culture itself was performed on an agarose medium in order to prevent overgrowth by fibroblasts. Untreated samples formed 43 +/- 5 clones, explants treated with MPA only produced 39 +/- 5 clones, a difference which was not statistically different; samples irradiated without pretreatment produced 16 +/- 8 and samples after combined treatment 9 +/- 3 clones (all values means +/- SD). This numeric reduction of cell growth through preirradiation treatment with MPA was statistically significant. The effect of MPA as a radiosensitizer may be due to its potential to prolong the radiosensitive G2 phase of the cell cycle. This effect of MPA may be useful also in other hormone-dependent tumors

[en] The alpaca and llama are considered to be seasonally reproductive (from December to March) and given good feeding conditions are reproductively active throughout the year. The males reach puberty at the age of about 2 years when they are free from peno-preputial adhesions. Puberty in the females is affected by body weight and may be reached at the age of 12 months. The females do not have sexual cycles but follicular waves, therefore oestrus varies from 2 to 36 days. Copulation takes place in a seated position and lasts from 5 to 50 minutes; ovulation is induced by coitus, hCG, GnRH and the semen of the alpaca and the bull. 'Spontaneous' ovulation has been observed at the height of the reproductive season and is caused by mechanisms which are not well defined. Multiple ovulation occurs in 10% of females but the number of multiple births is very low. The corpus luteum (CL) forms after mating, attaining maximum size and having the greatest secretory activity on day 9(14.0 nmol/L); it lasts for the 11 months of gestation. If there is no pregnancy, shrinkage of the corpus luteum begins between days 10 and 13 and the progesterone levels fall rapidly. The incidence of embryonic mortality during the first two months of gestation is high. Gestation lasts approximately 342 days, and 93.5% of births occur during the daytime when the environmental conditions are favourable for the newborn animal. The placenta is diffuse and epitheliochorial. Uterine involution is completed within 20 days after birth. Intra- and inter-specific artificial insemination tests have been carried out with intra-uterinal implantation of semen. Embryonic transplant tests have also been conducted. (author)

[en] Oestrous cycles of shorter duration (8-12 days) are usually found when either dairy or beef cows resume cyclicity post partum. The incidence of short cycle is so high that it should be considered a normal physiological phenomenon. Strong evidence in beef cattle suggests that the short cycle follows an ovulation (probably the same in dairy cows). In dairy cows it is likely that a premature release of prostaglandin is responsible for the short luteal phase (probably the same in beef cows). The occurrence of short oestrous cycles is incompatible with the establishment of pregnancy. In water buffaloes the occurrence of short oestrous cycles following weaning has to be considered and breeding of animals subsequenty adjusted. (author)

[en] [4-¹⁴C]-Progesterone is converted into [4-¹⁴C]-20, 20-ethylene-dioxypregn-4-ene-3-one through the eniminium perchlorate intermediate. Silylation of the ethylenedioxy derivative gives rise to [4-¹⁴C]-3β-trimethylsilyloxy-20, 20-ethylenedioxypregna-3,5-diene which is reduced stereospecifically into [4-¹⁴C]-3β-hydroxy-20, 20-ethylenedioxy-5-pregnene. Cleavage of the protecting group leads to [4-¹⁴C]-pregnenolone with a radiochemical yield of 50% based on [4-¹⁴C]-progesterone after purification; specific activity: 59mCi/mM