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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
PubMed1986

Demonstration of 20K growth hormone in human plasma by gel electrophoretic-immunostaining-autoradiographic assay (GEISAA).

A variant of human growth hormone (hGH), in which 15 amino acids are missing (commonly referred to as 20K-hGH in contrast to the traditional form which is referred to as 22K-hGH), is known to exist in human pituitary glands. However, lack of a method to measure it in blood has hindered investigations of its physiopathology. We have applied a newly-developed technique called GEISAA for its detection in small volumes of human plasma. The method is based upon the lower Mr of the variant and its ability to partially crossreact with existing antibodies for 22K-hGH. It consists of retrieval of the substance from plasma by immunoprecipitation, separation from 22K-hGH by NaDodSO4-polyacrylamide gel electrophoresis, transfer onto nitrocellulose paper by electroblotting and visualization by immunostaining and autoradiography. It revealed the 20K-hGH in plasma of some normal individuals and in that of an acromegalic patient. Furthermore, plasma concentration of the variant rose in conjunction with 22K-hGH following exercise, a natural stimulus for GH release. These results show that the 20K-hGH circulates under normal conditions and it is measurable by GEISAA using existing antibodies.

Adult↗
PubMed1984

Antigenic sites of human growth hormone and related molecules detected by monoclonal antibodies to human growth hormone.

Four major antigenic sites for human growth hormone (hGH) were identified by 27 mouse monoclonal antibodies to hGH. Sites 1 and 2 are spatially close whereas sites 3 and 4 are located in other parts of the molecule. There also appears to be a subdivision of antigenic sites. A panel of 10 monoclonal antibodies, which included representatives from each antigenic site group, were used to determine cross-reactivities between hGH and human placental lactogen (hPL), human prolactin (hPRL), the 20,000 mol. wt variant of hGH (hGH20K) and a disulfide-linked dimer of hGH (diS-dimer). The data suggest a high conformational dependence of antigenic sites in hGH. DiS-dimer retains all four antigenic sites of hGH, although all have been altered. hGH20K retains sites 2-4 but site 1 has been dramatically altered. hPL retains site 3, whereas sites 1 and 4 have been dramatically altered and site 2 may be lacking. The extremely low cross-reactivity observed for hPRL is consistent with the dissimilarity between hGH and hPRL. Antigenic site 3 is the most conserved of all sites. The lack of structural similarity compared with hGH of site 1 in hGH20K and of a portion of site 3 in diS-dimer suggests that it may be possible to develop specific radioimmunoassays for these structural variants of hGH.

Antibodies, Monoclonal↗
PubMed1983

Radioimmunoassay of human prolactin based on a 13 amino acid synthetic analog of the amino terminus.

A 13 amino acid analog of the human prolactin amino terminus was synthesized, substituting tyrosine for valine at residue 13. The peptide was coupled to crystalline bovine serum albumin for antisera production. The peptide was used for iodination with 125I, and displacement curves were found to be parallel when human prolactin and the synthetic peptide were compared as standards. The radioimmunoassay using the synthetic peptide has the advantages of purity in its roles as hapten in the antigen and as labelled peptide, of ease of iodination of the peptide, of its stability after iodination, and of obviating the need for native human prolactin. The radioimmunoassay is suitable for the measurement of human prolactin concentration in plasma.

Amino Acid Sequence↗
PubMed1983

Production of antibodies by inoculation into lymph nodes.

The intra-lymph node technique used to inoculate rabbits with small quantities of antigen has been described. A variety of antigens in the 20,000-22,000 molecular weight range, as well as a 15-amino acid peptide coupled to BSA, have been inoculated successfully by this procedure. We have made no attempt to compare the success rate of the intra-lymph node inoculation route with other techniques utilizing small (microgram) quantities of antigen.

Animals↗
PubMed1982

The biological half-life of human growth hormone and a biologically active 20,000-dalton variant in mouse blood.

We compared the disappearance rate of hGH and hGH20K injected into groups of mice. Radioactivity measurements and RIA were used to determine the amount of hormone in blood collected at various times after injection. The results indicate that the T1/2 value for hGH and hGH20K are equal. We conclude that there is no apparent relationship between the equal rates of disappearance, the dissimilar binding characteristics that have been shown for the hormones and their equipotent growth promoting activities.

Animals↗
PubMed1980

Effects of calcium, lanthanum, and temperature on the fluidity of spin-labeled human platelets.

Previous platelet studies have shown that calcium plays important roles in stimulus-secretion coupling, aggregation, and other membrane-associated functions. In addition, lanthanum induces platelet aggregation and the platelet release reaction and also influences platelet responsiveness to various stimuli. The spin-label results presented here suggest that one mechanism through which calcium and lanthanum mediate their effects on platelet functions may be by decreasing the lipid fluidity of the surface membrane. The structure of platelet membrane lipids was examined with the spin-label method. Washed human platelets were labeled with the 5-, 12- and 16-nitroxide stearic acid spin probes. Order parameters which measure the fluidity of the lipid environment of the incorporated probe may be calculated from the electron spin resonance (ESR) spectra of 5-nitroxide stearate [I(12,3)]-labeled cells. Evidence is presented which indicates that these spectra principally reflect properties of the platelet surface membrane lipids. The membrane fluidity increased with temperature for the range 17 to 37 degrees C. Either calcium or lanthanum additions to intact cells increased the rigidity of the platelet membranes at 37 degrees C, although the La3+ effect was larger and occurred at lower concentrations than that of Ca2+. For example, addition of 1 mM La3+ or 4 mM Ca2+ increased the order parameter of I(12,3)-labeled platelets by 4.3 +/- 1.7% or 2.1 +/- 0.5%. Preliminary studies conducted on purified platelet plasma membranes labeled with I(12,3) indicated that 1 mM LaCl3 or 4 mM CaCl2 additions similarly decreased the lipid fluidity at 37 degrees C. The above cation-induced effects on the fluidity of whole platelets were reversed by the use of the divalent cation-chelating agent ethylene glycol-bis-(beta-aminoethyl ether)-N,N'-tetra-acetic acid (EGTA). Lastly, lanthanum (0.2-1 mM) caused rapid aggregation of platelets which were suspended in a 50-mM Tris buffer pH 7.4 that did not contain adenosine.

Blood Platelets↗
PubMed1979

Glycohemoglobins and glucose tolerance.

Glycohemoglobin (GHb) levels were assayed after chromatography on weakly acidic acrylic cationite columns in 167 patients undergoing glucose tolerance test (GTT) and in 105 known diabetics. In 95% of patients with normal GTT levels, the GHb level was in the range of 6.8% to 9.8%. The GHb level was normal in patients with latent diabetes. Glycohemoglobin levels were elevated in patients with poorly controlled diabetes. Even in patients with normal GTT results, GHb levels correlated positively with fasting plasma glucose and glucose tolerance values. In patients with abnormal GTT results or diabetes but not receiving insulin therapy, the correlation between GHb levels and fasting plasma glucose values was significant. The GHb level that distinguished between latent and overt diabetes correlated strongly with the values of fasting plasma glucose and glucose tolerance and reflected changes in the control of diabetes.

Adult↗
PubMed1979

Effect of 2-deoxyglucose on [32P] phosphate and insulin release from perifused rat pancreatic islets.

The effect of 2-deoxyglucose on glucose mediated insulin and [32P]phosphate release was studied by perifusion of isolated rat pancreatic islets. When islets were perifused with media containing 2.8 mmol/l glucose and 20 mmol/l 2-deoxyglucose for 60 minutes and then exposed to media containing 8.3 or 16.7 mmol/l glucose and 20 mmol/l 2-deoxyglucose for the next 15 minutes, insulin release at either glucose concentration was prompt but blunted. Similarly, islets preincubated (90 min) with [32P] orthophosphate, then perifused with 20 mmol/l 2-deoxyglucose for 75 min and stimulated by either 8.3 or 16.7 mmol/l glucose for the final 15 minutes or 2-deoxyglucose exposure demonstrated obtundation of [32P]phosphate release. Perifusion of islets with 20 mmol/l 2-deoxyglucose alone induced no heightened 32P efflux. These studies suggest that 2-deoxyglucose affects initial events in stimulus-secretion coupling of glucose mediated insulin release.

Animals↗
PubMed1978

Insulin secretion from pancreatic islets: effect of growth hormone and related proteins.

Insulin responses to clinical grade human growth hormone (hGH), intact hGH, naturally occurring diabetogenic substance (NDS), and subtilisin cleaved forms of hGH (S1 and S3) were studied using hypophysectomized rat pancreatic islets. While clinical grade hGH (200 microgram/ml) elicited a prompt and sustained release of insulin, purified intact hGH (200 microgram/ml) did not. Naturally occurring diabetogenic substance, isolated from clinical grade hGH preparations, stimulated insulin release at 200 ng/ml. Upon repeat stimulation with NDS, a significantly greater insulin release than with initial stimulation was observed. Although S3 (200 microgram/ml) elicited significant insulin release, S1 (200 microgram/ml) did not. Direct stimulation of insulin release with clinical grade hGH is not due to intact hGH but another proteins(s) such as NDS. Enzymic modification of intact hGH appears to enhance insulin stimulatory capacity.

Animals↗