Biomedical subjects
Publications and source records attributed to A F Parlow.
For the first time the entire linear amino acid sequence of hPRL has been ascertained. The sequence features 198 amino acid residues, leucine at the NH2-terminus, and 6 half custines. hPRL sequence identity with porcine, ovine, and rat PRL is 77, 73, and 60%, respectively. However, hPRL sequence identity with hGH is only 16%, and with human placental lactogen 13%.
Consecutive daily serum samples were obtained over 25-30 days from 2 pre-pubertal girls (Stage I), 2 girls with breast development alone (Stage II); one girl with both breast development and pubic hair (Stage III), and 2 girls who were six months and three years post-menarche, respectively (Stage IV). All serum samples were assayed for LH, FSH, progesterone and 17-hydroxyprogesterone. Sera from 6 girls were assayed for testosterone, and sera from 3 were assayed for oestradiol. The patterns of gonadotrophins and sex steroid concentrations in both Stage I and Stage II girls were characterized by day to day stability. LH and FSH concentration was increased in Stage II subjects, while steroid concentration were similar to those in Stage I. The Stage III subject showed marked, apparently random, fluctuations in the concentrations of LH, FSH, oestradiol and 17-hydroxyrogesterone. In Stage IV, as early as six months post-menarche, there was a definte peak in the serum concentration of gonadotrophins, 17-hydroxyprogesterone and oestradiol. However, luteal phase length and maximal progesterone levels of these post-menarchial girls were less than those observed for normal adult females. These data are consistent with evolution of the adult menstrual pattern of hormone secretion through a series of developmental stages.
A sensitive, semi-quantitative radioimmunoassay method to screen for elevations of TSH concentration in blood is described. The method requires two 0.32 cm dots of dried blood-impregnated filter paper (equivalent to 3 mul plasma) and a 3-day incubation. Separation of bound and free is obtained using polyethylene glycol. The method can recognize TSH concentrations as low as 22 muU/ml using a highly sensitive antiserum developed by one of us (AFP). TSH in dried cord and newborn blood from 4 infants with congenital hypothyroidism was clearly higher than in normal infants. The method is suitable for use in a newborn screening program to confirm the suspicion of primary hypothyroidism in specimens with low T4 concentrations.
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Serum levels of testosterone, estradiol, progesterone, 17alpha-hydroxyprogesterone, follicle-stimulating hormone, and luteinizing hormone were measured in 16 boys with pubertal gynecomastia. Six patients had elevated serum estradiol concentrations, and four of these six also had elevated progesterone levels. Serum estradiol/testosterone ratios were high for the stage of puberty in 11 of the 16 patients. In five patients who had two or more determinations, the steroid concentrations returned toward or into the normal range. Transient increases in serum estradiol concentration or an abnormally high estradiol/testosterone ratio may be causally related to the development of gynecomastia in adolescent boys.
A highly purified preparation of rat thyrocalcitonin (TCT) has been obtained from lyophilized thyroid glands by gel chromatography following acid-acetone extraction. Biological activity of Sephadex G-50 eluates appeared in two peaks. The TCT in the major peak was concentrated, and applied to a Bio-Gel P-6 column, and a major protein peak was eluted which coincided with TCT activity. Potency, estimated by bioassay in rats, increase approximately 3500-fold from 0.075 MRC U/mg lyophilized glands to 250-400 MRC U/mg in the final product. The overall yield of TCT activity was about 36%. The purified product was characterized by chemical procedures and evaluated for its antigenic properties and use for radioimmunoassay. The purified rat TCT was used both labeled with 125I and as unlabeled standard. The following results were obtained: 1) Guinea pig antisera to either human or rat TCT were capable of binding 125I-rat TCT or 125I-human TCT; 2) Using either 125I-human or 125I-rat TCT and antisera to either TCT, pg amounts of rat and human TCT reacted in the assay while ng to mug amounts of salmon calcitonin or porcine TCT failed to react; 3) Using 125I-rat TCT and antisera to human or rat TCT, synthetic C-terminal (10-32 or 22-32) fragments of human TCT reacted well, while N-terminal (1-18) or desamide (1-32) derivatives reacted poorly or not at all; 4) Rat TCT was easily detected in normal thyroid venous plasma (5-10 ng/ml) and thyroid gland extracts (similar to 1 mug/gland) but not in peripheral blood; 5) Bioassay and radioimmunoassay of rat thyroid extracts (N equals 18) showed good agreement (r equals 0.86, p less than 0.001). The results support the idea that rat TCT is closely related to human TCT, indicate that major antigenic determinants reside in the C-terminal portion of the molecule, and show that antisera to either human or rat TCT can be used to measure rat TCT.
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hLHa, whose primary amino acid sequence is known, was reduced and s-carboxymethylated (RCM) to remove secondary and teriary structure. RCM-hLHa was utilized for development of a "sequence specific" ria. RCM-hLHa ria revealed that the NH2-terminal tryptic peptide of hLHa (consisting of only 32 amino acid residues) was nearly as immunoreactive as the entire RCM-hLHa molecule (consisting of 89 residues). No other tryptic peptide was immunoactive. Reduced and s-carbamidomethylated hLHa, differing only slight in structure from RCM-hLHa, was weakly active in the RCM-hLHa ria, demonstrating the utility of this ria for precise study of structure-immunologic activity relationships.
A high-sensitivity radioimmunoassay for human thyroid-stimulating hormone (hTSH) has been developed utilizing a highly specific rabbit antibody (developed by AFP) to hTSH with an affinity constant of 4.4 x 10(11) M-1. Optimal conditions which minimized both 125I-hTSH radiation damage and 125I dissociation included storage at -60 C in 0.25% albumin. Repetitive freezing and thawing did not cause loss of structural integrity or of full immunochemical reactivity of 125I-hTSH. Effects of human and calf sera on the precipitation of first antibody-bound 125I-hTSH by second antibody have been tabulated; the addition of TSH-free human serum to the standard curve is necessary to compensate for the serum effect. The minimum detectable amount of TSH in the new assay at a 1:1,000,000 final dilution of the hTSH antibody is 0.02 muU/tube. The mean normal hTSH value of 1.5 +/- 1.0 muU/ml (mean +/- SD) fell within the central one-third of the logit (B/Bo) plot where antigen concentrations are measured with highest precision. This assay gives good precision and reproducibility of measurements throughout the normal range of serum TSH concentrations.
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