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Biomedical subjects

W P Vanderlaan

Publications and source records attributed to W P Vanderlaan.

At least 19 recordsLinked to original sources
PubMed1987

Detection of multiple PRL- and GH-like proteins in human pituitary by Western blot analysis.

Surgically removed normal and tumorous pituitary tissues from a prolactinoma patient were analyzed by Western blot techniques for PRL and GH variants. Criteria for identification were the Rf of the bands within the gel, immunologic crossreactivity to specific antisera, and structural verification by tyrosine peptide-mapping of individual bands from the gel. The authors found the tumor-tissue to be characterized by the presence of a PRL band greater in concentration than in the normal tissue and the virtual absence of a GH band. Immunoblotting of the electrophoretically resolved proteins form both types of tissues revealed several new bands crossreactive with human PRL and GH antibodies. Some of the new bands were of Mr greater than the monomeric PRL and GH and others were of lower Mr. Relative of two of the low mobility Mr PRL-immunoreactive bands designated as 16K and 8K corresponded to the Rf of the two fragments of cleaved PRL, which suggested that cleaved PRL occurred naturally in the human pituitary gland. The most conspicuous of the new PRL-immunoreactive bands, a 25,000 Mr protein migrating slightly behind PRL, displayed strong crossreactivity to hPRL antibodies and was present in greater concentration in the prolactinoma tissue than in the normal tissue. These properties suggested that it was related to hPRL and perhaps represented its glycosylated variant. However, its tyrosine peptide map did not resemble that of hPRL. Thus, it is not clear whether it represented G-hPRL or a new pituitary protein that cross-reacts with hPRL antibodies. In addition, two other bands of low Mr, designated as unknown 1 and unknown 2, reacted with hPRL antibodies. Immunostaining with hGH antibodies revealed the 20K-hGH variant, the F1 fragment of cleaved hGH, and a pair of new bands immediately behind GH that could represent glycosylated hGH--possibly a product of Seeburg's variant hGH gene. Both PRL and GH antibodies elicited numerous bands of high Mr by the technique employed, far more than ever observed by Sephadex chromatography. The nature of the high Mr bands remains unknown. Further characterization of these new PRL- and GH-immunoreactive proteins might help in the understanding of the multiple physiologic functions of PRL and GH in man.

Adenoma↗
PubMed1985

Glycosylated human prolactin.

A glycosylated form of human PRL (G-hPRL) was isolated from pituitary glands. The glycoprotein was separated from the major form of PRL on columns of lentil lectin-Sepharose 4B. The major form of PRL did not bind to the lentil lectin, whereas the glycosylated modification did and could be eluted with methyl-alpha-D-mannopyranoside. By gel electrophoresis in sodium dodecyl sulfate, a mol wt of 25,000 was estimated for the glycosylated PRL. The mol wt of hPRL is 23,000. In a RIA for hPRL, the glycosylated hormone was about one third as reactive as the principal form. Since there is only one Asn-X-Ser(Thr) sequence in hPRL, the asparagine at position 31 is the likely point of N-linked glycosylation.

Chromatography↗
PubMed1982

Effect on growth of prolactin deficiency induced in infant mice.

The effect of lowering PRL levels in blood during early infancy on subsequent growth and development was studied in mice. PRL was reduced by injecting either an antiserum raised against homologous PRL or a PRL-inhibiting drug, 2-chloro-6-methylergoline-8 beta-acetonitrile methanesulfonate (ergoline), into 4-day-old mice for a period of 4 or 5 days. Both the anti-PRL serum and ergoline rapidly killed some of the injected animals, but the effect of anti-PRL serum was much more severe than that of ergoline (39% vs. 8.7% mortality during the period of injection). Similar administration of an antiserum against mouse GH or the GH-inhibiting peptide somatostatin did not cause a significant number of deaths. The deaths from the anti-PRL serum largely ceased when the antiserum was neutralized with rat PRL (NIH-RP-1) before injection. The gain in body weight of baby mice was markedly retarded within 24 h of injecting anti-PRL serum and ergoline, in contrast to the anti-GH serum and somatostatin injections, which took 3--4 days to inhibit growth perceptibly. The anti-PRL serum, despite having only one eighth the titer of anti-GH serum, was by far the most effective of the two antisera in diminishing tibial epiphyseal cartilage width as well as weights of pituitary glands, testes, and adrenals and retarding sexual maturity. The more severe and generalized developmental abnormalities and the incidence of mortality as a result of anti-PRL serum administration suggest that PRL in mice may be involved in the maintenance of some vital function during infancy.

Animals↗
PubMed1981

Binding characteristics of a biologically active variant of human growth hormone (20K) to growth hormone and lactogen receptors.

The dose-dependent displacement characteristics of a biologically active 20,000 molecular weight human pituitary growth hormone variant (20K) and of human growth hormone (hGH) were compared using hGH liver plasma membrane receptors both from 20-30 day pregnant rabbits and from normal female rats and also using mammary gland plasma membrane receptors from 5-6 day lactating rabbits. Different preparations of 20K were found to be only 3-20% as potent as hGH when compared at the dose necessary to cause 50% displacement of (125I)iodo-hGH from liver receptor and was 22-53% as effective as hGH in the mammary receptor assay system. These findings suggest that 20K and hGH may have separate receptors or that the binding characteristics of the two hormones may be quite different.

Animals↗
PubMed1979

Serum, pituitary and urine concentrations of prolactin and growth hormone in eight strains of mice with varying incidence of mammary tumors.

Eight inbred strains of mice with varying incidences of spontaneous mammary tumor were compared in regard to prolactin and growth hormone concentrations in sera, pituitary glands and urine. Serum prolactin was compared under basal conditions as well as after stimulation with perphenazine. Both hormones were measured with specific, homologous radioimmunoassays. Although some strains having a high incidence of mammary tumors had high levels of prolactin in sera, urine and pituitary glands, neither basal nor perphenazine-induced serum concentrations showed a consistent pattern across mouse strains that correlated with the incidence of mammary tumors. Growth hormone levels in sera, pituitary glands and urine also had no characteristic pattern that applied to all strains studied. The ratio of prolactin depleted from the pituitary gland to prolactin detected in serum after perphenazine injection, which reflected the metabolic clearance rate of prolactin, was highest in two strains with a high incidence of mammary tumors and relatively lower in low-tumor strains. These results suggest that if prolactin plays a part in mammary tumor development in mice, its mechanism varies with strains: while hyperprolactinemia may be the means in some strains, a peculiarity in the metabolism of the hormone may be more important in others.

Animals↗
PubMed1979

Comparative potency of subtilisin-cleaved and intact human growth hormone measured in growth hormone-deficient human subjects.

Eight GH-deficient subjects received both subtilisin-cleaved human GH (hGH-S) and intact hGH (hGH-I) during short term balance studies to compare the potency of these two forms of GH. Both forms caused nitrogen retention, calciuria, postassium retention, and elevation of blood glucose. The effects on plasma insulin concentrations were inconstant at the doses used. hGH-S was more potent than hGH-I, as measured by nitrogen and potassium retention, and the differences reached levels of statistical significance. hGH-S also caused greater calciuria and increases in fasting the postprandial blood glucose and in postprandial insulin in absolute terms, but these differences did not reach levels of statistical significance. In no instance was hGH-I significantly more potent than hGH-S. We conclude hGH-S, a two-chain form of hGH, caused significantly greater nitrogen and potassium retention in human subjects in short term balance studies than hGH-I.

Blood Glucose↗
PubMed1977

Serum and pituitary concentrations of prolactin and growth hormone in mice during a twenty-four hour period.

The objective of this study was to investigate changes in the secretion of prolactin (PRL) and growth hormone (GH) occurring during a 24 h period in the mouse. Adult female mice of the C57BL/St strain and male mice of the C3H/St strain, maintained on a 14 h light and 10 h dark schedule, were used. Serum and pituitary concentrations of PRL and GH were measured by radioimmunoassay in samples collected by decapitation at hourly intervals through 24 h. Serum PRL concentrations in female mice averaged higher during the daylight hours and lower at night. However, the pattern was just the opposite in males: the values were lower during the day time and higher and variable during the night. Pituitary PRL levels dropped significantly after the onset of the dark phase in mice of both sexes. Serum GH concentrations of female mice did not fluctuate significantly with the time of the day, but those of male mice displayed a distinct flux: the levels were low from 0800 h until 1500 h, began to rise in the afternoon, and remained relatively high throughout the night. Pituitary levels of GH did not change with time in mice of either sex. The data suggest the existence of daily rhythms in the secretion of PRL and GH in mice, with marked differences related to sex. In general, the changes were most pronounced for serum PRL in females and for serum GH in males.

Animals↗