Spontaneous dissociation of human pituitary luteinizing hormone in solution.

Aliquots of a solution of highly purified human pituitary LH (hLH) were incubated with variations in temperature and time. The incubates were chromatographed on Sephadex G-100 as well as on DEAE-Sephadex A25. The column effluents were assayed in radioligand assay and in specific hLH alpha- and hLH beta-RIA systems. The results indicate that there is spontaneous dissociation of hLH at elevated temperatures under otherwise "normal" conditions concerning, for example, pH and ionic strength. The degree of dissociation is both time and temperature dependent. This dissociation is not due to proteolytic enzymes. It is concluded that one should be alert when using hLH subunit RIA systems at elevated temperatures for measuring hLH levels, e.g. in clinical samples, because artificial high levels may be obtained.

Determination of hepatitis A antibody response to vaccination by an enzyme immunoassay.

The quantitative responses to vaccination with hepatitis A vaccine was determined in 113 volunteers using a commercially available enzyme-linked immunosorbent assay for total antibodies to hepatitis A. Administration of vaccine or control preparation was carried out according to two regimens; at 0, 1 and 12 months (regimen I) and at 0, 0.5 and 12 months (regimen II). Seroconversion rates (concentrations of HAV antibodies > 50 IU/l) were between 94 and 97% at month 1 for regimen I and regimen II, respectively. The geometric mean titres (GMTs) fell gradually by month 12, and increased rapidly 10-100 fold 1 month after the booster dose at month 12. The GMTs of the groups receiving the control preparation remained below 50 IU/l. No significant differences were found between the antibody responses after regimen I or regimen II. It is concluded that the antibody test (Hepanostika HAV Antibody) can be used safely and adequately for quantitation of responses to hepatitis A immunisation.

Circadian rhythm of prolactin during the menstrual cycle.

Ten women with regular cycles volunteered in a study of the relationship between PRL diurnal rhythm and menstrual cycle. A PRL surge during the afternoon between 2:00 and 8:00 P.M. was observed in the luteal and periovulatory phases, but not in the early follicular phase. The authors advise PRL measurement in the morning between 10:00 A.M. and 12 noon for diagnosing hyperprolactinemia, because morning PRL levels seem to remain constantly low during the menstrual cycle.

Reproduction in the vervet monkey (Cercopithecus aethiops): I. Testicular volume, testosterone, and seasonality.

To test whether the male could contribute to the birth peak seen in both wild and captive vervets, testicular volume and peripheral testosterone concentration were measured monthly in nine adults throughout a 14-month period. Volume was an average of 15% greater during the months of June to September, the period of natural breeding activity in the wild, than at other times of the year. Testosterone concentration rose throughout the time period but did not correlate with testicular volume. Quarterly biopsies of the right testis in animals either used for or withheld from breeding revealed the presence of spermatozoa and the existence of spermatogenesis throughout the year. There was no correlation of testicular volume with breeding status or biopsy. If these results from individually caged animals are representative of group-caged and wild animals, then such small seasonal changes are unlikely to affect year-round breeding. Therefore, a physiological contribution by the male to natural birth peaks seen in the wild and captivity is not readily apparent.

Reproduction in the vervet monkey (Cercopithecus aethiops): II. Annual menstrual patterns and seasonality.

Menstrual patterns and progesterone levels were monitored for 5 years from a cohort of 28 female vervet monkeys that were individually caged indoors. Three distinct cycle types (short, normal, and prolonged) were defined according to cycle length. Mean length of the normal cycle (32.5 days) and menses duration (4.8 days) are in agreement with previous reports. Prolonged cycles (> 50 days) contributed 20% of the total, with a decreased incidence during the natural peak breeding period. Weekly progesterone measurements indicated that many prolonged cycles were associated with an extended luteal phase, while others were probably due to lack of ovulation. From these data it would appear that the vervet monkey, although not strongly seasonal, does favor a particular time of year for breeding in a colony housed indoors.

[Marius Tausk (1902-1990), influential endocrinologist and producer of medicines; a retrospect to mark the centenary of his birth]. / Marius Tausk (1902-1990), invloedrijk endocrinoloog en producent van geneesmiddelen; terugblik bij zijn honderdste geboortedag.

Marius Tausk, born in Sarajevo, studied medicine at Graz in Austria. In 1926, he attended a socialist youth rally in Amsterdam. Whilst there, he met Prof. Ernst Laqueur, a pharmacologist in Amsterdam, who offered him a position at Organon, a newly-founded pharmaceutical company in Oss, the Netherlands. He remained in the Netherlands and became the driving force behind this innovative company. Tausk made many contributions to new developments across the field of endocrinology, including the discovery of the adrenal steroids (together with T. Reichstein, Nobel Prize Laureate in 1950), and the development of oral contraceptive pills. He was astute enough to quickly patent the first corticosteroids. He could quickly extract the essential elements from an information source and disseminate this in five languages. His sharp judgment brought him friends and admirers, yet also those who feared him. In 1937 he was appointed as a private lecturer at the Medical Faculty of Utrecht University and in 1956 he was made Special Professor of Theoretical Endocrinology. He was awarded a number of scientific distinctions including two honorary doctorates. In 1949 he was honoured with the Knighthood of the Order of The Netherlands Lion.

Pseudohyperparathyroidism associated with perirectal adenocarcinomas in elderly female dogs.

In 8 elderly female dogs a syndrome of hypercalcaemia and hypophosphataemia was found in association with a perirectal adenocarcinoma. Following removal of the tumour the hypercalcaemia resolved within two days in four of the five operated animals.

Early detection of pregnancy in rhesus and stump-tailed macaques (Macaca mulatta and Macaca arctoides). Evaluation of two radioimmunoassays and a hemagglutination inhibition test.

Chorionic gonadotropin (mCG) in serum and urine of monkeys was determined by a radioimmunoassay and hemagglutination inhibition (HAI subhuman primate tube test for pregnancy). HAI-positive pregnancy tests coincided fully with the mCG excretion patterns as determined by RIA (oLH beta system). The least reliable system was the hCG-beta RIA. The HAI test allowed accurate prediction of the parturition date.

A radioimmunoassay for pregnancy associated protein, beta 1SP1: levels in pregnancy, trophoblastic and neoplastic disease.

A radioimmunoassay system for the glycoprotein beta 1SP1, one of the pregnancy-associated proteins, has been set up. beta 1SP1 levels in normal pregnancy have been established transversally. Clearance (t1/2) from the circulation postpartum ranged from 1.4 to 1.8 days. Several patients with trophoblastic disease, e.g., mola hydatidosa, choriocarcinoma and embryonic cell carcinoma, were followed longitudinally. Human chorionic gonadotropin (hCG), a highly reliable tumor marker in trophoblastic disease, has been determined concomitantly by radioimmunoassay. In all instances, hCG proved to be a better indicator of the presence of a tumor, because by the time beta 1SP1 became undetectable, hCG could still be detected. Samples from a large multicenter study on trophoblastic disease were studied: out of 100 positive for hCG, beta 1SP1 could be detected in 86; however, out of 21 samples in which hCG was not detectable, 1 was found to be positive for beta 1SP1. In a number of samples from patients with bronchial carcinoma, no beta 1SP1 could be detected.

An unexpected effect of L-5 hydroxytryptophan-ethyl-ester combined with a peripheral decarboxylase inhibitor on human serum prolactin.

While the 5-HT precursors tryptophan and 1-5-HTP cause an increase in serum prolactin concentration, a combination of 1-5-HTP with a peripheral decarboxylase inhibitor was found to reduce the serum prolactin concentration. This combination seemed to behave like a DA agonist. This effect is not produced by the decarboxylase inhibitor per se. A possible explanation is that 5-HTP is converted to 5-HT in CA-ergic neurons, that 5-HT supersedes the CA from the stores, and that some of the CA reach the synaptic cleft and stimulate CA receptors. Another possible explanation is that 5-HTP decarboxylase is centrally inhibited as well, and that an effect of 5-HTP itself is involved here. In view of the observations made it is doubtful whether the therapeutic effect of 5-HTP combined with a peripheral decarboxylase inhibitor in depressions and myoclonus can in fact be atributed to activation of central serotonergic systems.

Human thyrotropin and its alpha and beta subunits.

A new procedure is described for the isolation of human thyrotropin using ion exchange chromatography and gel filtration only. Thyroid stimulating activity of the final preparation of our human thyrotropin amounted to 0.5 IU/mg by bioassay. The alpha and beta subunit of the hormone were also obtained by a new procedure. In this method the native hormone was incubated in an acidified 8 M urea solution and the chains were then separated by ion exchange chromatography and gel filtration. The amino-terminal residues of the alpha and beta chains were valine and phenylalanine respectively. The beta chain appears shorter at its carboxy-terminal end by one methionine residue than its bovine counterpart. Cross-contamination of the subunit preparations were measured by radioimmunoassay. The beta chain exhibited a contamination of about 3 percent of the alpha subunit by weight. The alpha subunit is contaminated by about one percent of the beta chain by weight.

Is oxytocin present in platelets?

For arginine-vasopressin (AVP) it has been suggested that about 90% of the total amount present in peripheral blood is platelet-membrane bound. Oxytocin (OT) and AVP are nonapeptides which are similar in many respects. We investigated the possibility that OT might be found in platelet-rich plasma samples from patients undergoing ovarian super-stimulation for in-vitro fertilization purposes. These plasma samples were treated with acid repeated freezing/thawing and sonification in an attempt to solubilize or expose the possible bound OT. No differences between OT concentrations in platelet-rich or -poor plasma samples were found. We conclude that plasma OT is not bound or confined to platelets.