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Improved sensitivity and specificity of radioimmunoassays (RIAs) for hCG, hCG alpha and hCG beta have allowed measurements of these substances to become a powerful diagnostic aid applicable to several clinical disorders of pregnancy. In threatened abortion of the 1st trimester, the doubling time of hCG concentrations is significantly slower than in early normal pregnancies. Low levels of hCG are uniformly encountered in case of impending abortion. The overall predictive value of hCG determinations is 75-97%, whereas the predictive value of hCG alpha and hCG beta levels 88%. In patients progressing slowly to inevitable abortion, an increase in hCG alpha and/or the ratio hCG alpha: hCG is frequently observed. In ectopic pregnancies, sensitive new-generation tube tests and RIAs can detect urine or serum hCG in almost 100% of the cases. Abnormally low levels of hCG are encountered in about 85% of the patients. A significant increase in the ratio hCG alpha: hCG is observed. Toxemia of pregnancy is abided by significantly higher maternal levels of serum hCG, hCG alpha and hCG beta and by a lower ratio hPL: hCG than in normal pregnancies, or pregnancies complicated by isolated or chronic hypertension. It is concluded that in the above-mentioned pathological conditions of pregnancy, hCG is a reliable trophoblastic marker and that, additionally, hCG alpha could prove to be an index of chronic placental hypoxia.

Seasonal variation of prolactin nyctohemeral rhythm has been studied by radioimmunoassay on female cattle of the white blue belgian breed. Animals are divided into three groups as age is concerned : 6 calves, 6 heifers and 5 lactating cows. In december all groups of animals show a significant increase of plasma prolactin concentration between 5 a.m. and 7 a.m. Calves and heifers have a second secretion period either at the end of the afternoon between 17 and 19 p.m. or during the evening between 20 and 23 p.m. The circadian rhythm observed in may with heifers is similar to that in december with two waves whose relative importance is different at the two seasons considered. Nyctohemeral rhythm of prolactin in cattle is age and season dependent.

The maternal serum levels of hCG and its alpha or beta subunits were measured in 96 normal pregnancies and correlated with the fetal sex. During the first 20 weeks (69 cases), the maternal serum levels of hCG, of its alpha subunit and particularly of its beta subunit were higher in cases of female fetuses. However no statistically significant difference was observed between the levels of hCG or its subunits in serum of pregnancies with male or female fetuses. During the second half of pregnancy, the serum hCG levels were discretely higher in cases with female fetuses (no significant difference) and the serum levels of its alpha or beta subunits were identical in cases of male of female fetuses.

5 micrograms of human beta-endorphin were labelled with 2 mCi 125I by the chloramine T technique. After two gel filtrations on Sephadex G-15 and on Sephadex G-50 in phosphate buffer with EDTA, Trasylol and mercapto-ethanol, a pure tracer was obtained with a specific activity about 150 microCi/ug. Kept at + 4 degrees C, the tracer remained utilizable for 30 days without loss of immunoreactivity. The labelling with lactoperoxydase and the use of another gel filtration method (filtration on Aca 202) gave a 125I beta-END tracer with the same immunoreactivity. The binding of this tracer to the antibody of an anti-beta-END antiserum diluted at 1/8000 was 32% with a non specific binding of 2%. 5 micrograms of human beta-lipotropin were labelled with 0.5 mCi 125I by the lactoperoxydase method. After two gel filtrations on Sephadex G-25 and on Sephadex G-75 in phosphate buffer with EDTA, Trasylol and mercapto-ethanol, a pure tracer with a specific activity of 140 microCi/micrograms was obtained. It remained utilizable for 30 days when kept at + 4 degrees C. Gel filtration on Aca 202 did not give good purification, while gel filtration on Aca 54 was good but slower than on Sephadex G-75. The binding to antibody in absence of unlabelled beta-LPH was 32% for an anti-beta-LPH antiserum diluted at 1/4000. The non specific binding was 2.5%.

We have performed topical applications of HCG and LH on fixed paraffin-embedded sections of adult rat testes. Thereafter, immuno-cytochemical demonstration of the peptides was carried on and demonstrated that HCG and LH specifically bound to the cell membrane of Leydig cells. This technique is highly reproductible provided that adequate fixation (with formalin containing fixatives) as been performed.

The radioimmunological dosage of human prolactin using the hormone as tracer and reference and an anti-prolactin antiserum is described. The labeling of human prolactin is carried out in the presence of a small quantity of chloramine T (10 mug). The purification of the labeled hormone is carried out by gel filtration on Sephadex G-75 or by polyacrylamide gel electrophoresis. The optimal incubation conditions were found using a first incubation of 40-48 hours at room temperatures followed by an incubation of 4 to 6 hours with cellulose-bound second antibody. The interference of serum proteins is small. There is no cross reaction with follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), human chorionic gonadotrophin (HCG), human placental lactogen (HPL) and human growth hormone (HGH). However, cross reaction with ovine, bovine and rat prolactin is found. These cross reactions are complete with endogenous human prolactin and hormone of different origin. Serum prolactin was determined in normal subjects and subjects treated with TRH and bromoergocryptine.