Biomedical subjects

D W Heser

Publications and source records attributed to D W Heser.

5 recordsLinked to original sources

PubMed2000

Techniques to measure testosterone in the elderly.

In today's clinical and research settings, there is an unfortunate lack of consistency for the term "measuring testosterone status." This term is often used to refer to a measure of biologic androgen activity rather than the specific measurement of the chemical concentration of the testosterone steroid molecule. Even the measurements of chemical concentrations show considerable methodologic differences. This is true for measurements in elderly men, as well as in other populations, including women. All of the current methods for measuring total testosterone have limitations, especially with regard to low concentrations. In addition, unresolved questions concerning the active form of the hormone preclude definitive determination of which form of testosterone and which other androgen hormones are best suited for measuring androgen activity. When measurement techniques are compared, the numbers correlate with each other but certainly do not represent the same value. There is a need for a consensus as to which forms of hormones should be measured to best assess androgen status, and there is a need to standardize the procedures used to measure these hormones.

Aged↗

PubMed1986

Atrial natriuretic peptide elevation in congestive heart failure in the human.

A sensitive radioimmunoassay for atrial natriuretic peptide was used to examine the relation between circulating atrial natriuretic peptide and cardiac filling pressure in normal human subjects, in patients with cardiovascular disease and normal cardiac filling pressure, and in patients with cardiovascular disease and elevated cardiac filling pressure with and without congestive heart failure. The present studies establish a normal range for atrial natriuretic peptide in normal human subjects. These studies also establish that elevated cardiac filling pressure is associated with increased circulating concentrations of atrial natriuretic peptide and that congestive heart failure is not characterized by a deficiency in atrial natriuretic peptide, but with its elevation.

Adult↗

PubMed1984

Demonstration of biological activity of prolactin molecular weight variants in human sera.

Three immunoreactive forms of PRL, separated by Sephadex G-100 column chromatography, were identified in serum samples from 10 normal subjects and 7 patients with PRL-secreting pituitary tumors. Fractions eluted from the column were assayed for bioactivity by using a sensitive bioassay with the Nb2 cell line. Three molecular weight variants of PRL were identified in normal subjects. In samples from 9 of the 10 normal subjects, 80.1 +/- 3.6% (mean +/- SEM) of the total bioactivity eluted in a peak corresponding to a PRL monomer (peak III) with a mol wt of approximately 24,000, 18.3 +/- 3.7% eluted in a peak with a mol wt of approximately 56,000 (peak II), and 1.6 +/- 1.1% of the biological activity was in the void volume (peak I). In the 10th normal sample, 65% of the total bioactivity was in the void volume (peak I), 31% was in peak III, and 4% was in peak II. Samples from the patients had 3.6 +/- 0.7% of the total bioactivity in peak I, 9.3 +/- 1.0% in peak II, and 87.0 +/- 1.1% in peak III, percentages not significantly different from normal. For comparison with bioassay, RIA measurement of PRL was performed on all fractions of six samples (three normal subjects and three tumor patients). Good correlation was found between RIA and bioassay measurements under each of the three peaks identified. We conclude that 1) in sera from normal subjects, three molecular weight variants of PRL have biological activity; 2) in patients with PRL-secreting tumors, secretion of biologically active PRL molecular weight variants is not proportionately different from that in normal subjects; and 3) the results of the Nb2 PRL bioassay correlate well with PRL levels determined by RIA for each of three molecular weight variants identified.

Adenoma↗

PubMed1984

Simultaneous determination of 25-hydroxy- and 1,25-dihydroxyvitamin D from a single sample by dual-cartridge extraction.

With this dual-cartridge system we extract 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] from a single serum sample by using a nonpolar octadecylsilanol silica cartridge to adsorb the vitamin D metabolites and other nonpolar substances; the polar substances wash through the cartridge. The eluted material is then applied to a second alkylamine cartridge, which adsorbs the relatively polar hydroxylated metabolites; the less-polar substances are washed from the second cartridge. Elution from the second cartridge purifies and also separates 25(OH)D and 1,25(OH)2D with analytical recoveries near 90%. The monohydroxyl metabolites are determined by "high-performance" liquid chromatography (HPLC); the dihydroxyl metabolites are further purified by HPLC and determined by radioreceptor assay according to established procedures. Mean (+/- SD) winter normal values (34 subjects of both sexes; blood drawn in mid-April) were 18 +/- 5 micrograms/L for 25(OH)D and 25 +/- 7 ng/L for 1,25(OH)2D. In nine laboratory volunteers, the mean increase in the serum 25(OH)D3 value 5 h after ingestion of 50 micrograms of 25-hydroxycholecalciferol (Calderol) was 9 (SD 4) micrograms/L.

Absorption↗

PubMedDate not supplied

C-peptide immunochemiluminometric assay developed from two seemingly identical polyclonal antisera.

Two goats were immunized with synthetic C-peptide. Their antisera were immunopurified separately on a C-peptide affinity column. The purified antibodies from one goat were labeled with acridinium ester; the other goat's antibodies were immobilized on plastic beads. Standards were synthetic C-peptide. The new immunochemiluminometric assay (ICMA) for C-peptide was compared with our routine radioimmunoassay (RIA) by using Novo's 125I-labeled C-peptide and Cambridge Medical's antiserum. Good correlations were found between the new ICMA and the RIA (r = 0.951; ICMA = 1.07 RIA + 147; n = 112). The new ICMA showed good recoveries (91 percent to 108 percent) of added C-peptide and parallelism of diluted specimens. The incubation time was shortened from 48 hours for RIA to five hours for ICMA. In addition, it was shown that polyclonal antisera from two animals immunized by the same antigen and purified by the same affinity column can be used to prepare immunometric assays.

Animals↗