PubMed Health⌕ Search

Biomedical subjects

J M Gibbons

Publications and source records attributed to J M Gibbons.

12 recordsLinked to original sources
PubMed1996

In vitro inactivation of mammalian methionine synthase by nitric oxide.

The research described here provides one mechanism of uniting current effects of nitric oxide (NO) with the elevated levels of homocysteine detected in patients with cardiovascular and other disease. Time- and dose-dependent studies of the inhibition of purified mammalian methionine synthase by NO were performed. The in vitro study gave an effective IC50 value of 3 mu mol L-1. Methionine synthase converts cellular homocysteine to methionine and is a major enzyme in the biosynthetic pathways for folates, S-adenosylmethionine and biological methylations, sulphur amino acids and polyamines. Nitric oxide-induced inactivation of methionine synthase alters the levels of these metabolites and could therefore provide a connection between the cardiovascular effects of NO, the plasma homocysteine levels and cardiovascular diseases that is complementary to the more traditional NO-induced stimulation of guanylate cyclase and the convertion of homocysteine to oxidized sulphur amino acids.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1980

Amniotic fluid phosphatidylglycerol and phosphatidylinositol separated by stepwise-development thin-layer chromatography.

We describe a stepwise-development thin-layer-chromatographic technique for separating phosphatidylglycerol and phosphatidylinositol in samples of amniotic fluid. Plates are prepared from silica gel G slurried in a 50 g/L ammonium sulfate solution. Phospholipid phosphorus determination is not needed. Phospholipid phosphorus determination is not needed. Phosphatidylglycerol and phosphatidylinositol, measured densitometrically, are expressed as ratios to the sphingomyelin present. These ratios are correlated with the lecithin/sphingomyelin ratio and age of gestation in normal and abnormal pregnancies.

Amniotic Fluid↗
PubMed1980

Correlation of nonstressed fetal heart rate with sequential contraction stress test.

Two hundred seven high-risk patients were studied prospectively by standardized nonstressed fetal heart rate monitoring followed immediately by contraction stress testing (CST). Of the 604 combined procedures examined, 90.2% of nonstress tests (NST) were interpreted as reactive; none was associated with a positive CST. Of the nonreactive NSTs, 37% were followed by positive CSTs. These data support the contention that a reactive NST performed in compliance with a standard protocol is unlikely to be associated with a positive CST.

Female↗
PubMed1975

In vitro biosynthesis of TSH- and LH-releasing factors by the human placenta.

Human chorionic membrane and human placental tissue contain substances with the same elution volume as hypothalamic TRF and LRF standards during separation by carboxyl-methyl-cellulose ion-exchange chromatography. Homogenates prepared from fresh human placentas delivered at term caused release of TSH (thyroid-stimulating hormone) and LH (luteinizing hormone) when bioassayed in rats. After dialysis of placental homogentes, synthesis of biologically active TSH-and LH-releasing factors can be shown to occur in vitro following the addition of appropriate precursor amino acids and cofactors.

Amino Acids↗