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Biomedical subjects

M Horder

Publications and source records attributed to M Horder.

At least 19 recordsLinked to original sources
PubMed1980

Adrenal function in subgroups of the PCO syndrome assessed by a long ACTH test.

Fifteen patients with the polycystic ovarian (PCO) syndrome were classified into Group A (n = 6) and Group B (n = 9) based on their LH responses to LHRH before and at 44 and 92h after administration of oestradiol benzoate. Adrenal function in both groups was assessed by comparing the hormone responses to ACTH (0.5mg twice daily for 4 days) with those obtained in nine normally ovulating women during the early follicular phase of their cycles. In Group A patients there was no significant difference from normals in the serum concentration of dehydroepiandrosterone sulphate (DHAS), 17 alpha-hydroxy-progesterone (17-OHP) or androgens (testosterone and dihydrotestosterone). In contrast, the serum concentrations in Group B were significantly higher (P less than 0.01) for each of these steroids before ACTH, and remained higher at 2 and 4 days for DHAS, but not for the other two steroids. The concentration of oestrone was significantly higher (P less than 0.05) in Group B patients before, and 2 days after, ACTH, while in Group A patients higher concentrations (P less than 0.02) were found only after 2 days. The concentrations of oestradiol, on the other hand, were not different from normal in either group before ACTH and became lower than normal in both groups at 2 days and remained lower at 4 days in Group B. The concentration of cortisol was within the normal range throughout in Group A, but was lower than normal after 4 days in Group B patients (P less than 0.05). The ratios between the sums of concentrations of DHAS to cortisol on days 2 and 4 (P less than 0.001) or 17-OHP to cortisol (P less than 0.05) were elevated in Group B compared with normal subjects. LH, FSH and prolactin values were normal throughout in Group A, but in Group B patients the mean value for LH was significantly elevated before ACTH and at 4 days after ACTH (P less than 0.02).

Adrenal Glands↗
PubMed1977

Biological variability in aspartate aminotransferase activity in serum of healthy persons, and effect of in vitro supplemantation with pyridoxal 5-phosphate.

Aspartate aminotransferase (EC 2.6.1.1) activities in sera from nine healthy individuals were monitored during two weeks, both with and without first supplementing the serum with pyridoxal phosphate. Pyridoxal phosphate supplementation caused a mean increase of 39% (range, 33-55%) in measured activity. The biological variability during the two-week period was independent of pyridoxal phosphate supplemantation. The intra-individual variability (CV) was 5.3% and 5.1% with and without pyridoxal phosphate supplementation, respectively; the corresponding inter-individual variability was 13.2% and 13.6%. We conclude that the reference interval will be insensitive to intra-individual fluctuations in aspartate aminotransferase activity in serum, whether or not the serum is supplemented with pyridoxal phosphate.

Adult↗
PubMed1976

Aspartate aminotransferase activity in human serum. Factors to be considered in supplementation with pyridoxal 5'-phosphate in vitro.

The pyridoxal phosphate reactivation of the apo form of aspartate aminotransferase (EC 2.6.1.1) in human serum has been studied with "normal" and above-normal activity of this enzyme. The extent of the reactionation did not depend on the presence of the substrates, L-aspartate or 2-oxoglutarate. Reactivation was greatest with 110 mumol of added pyridoxal phsophate present per liter during a preinucation for 7 min in tris(hydroxymethyl)methylamine buffer wit;h serum volume fractions ranging from 0.017 to 0.267. In comparison with measurements prformed with no exogenous pyridoxal phosphate present, we found two potential sources of error when this cofactor was added: (a) reagent and sample blanks in the pyridoxal phosphate-supplemented system were two- to eightfold higher and (b) progress curves were nonlinear when L-aspartate rather than 2-oxoglutarate was used as the startin substrate. Aspartate aminotransferase measurement sith pyridoxal phosphate supplementation was slightly more precise than without.

Acute Disease↗