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Biomedical subjects

A G Herman

Publications and source records attributed to A G Herman.

At least 253 records · Page 14Linked to original sources
PubMed1979

Biosynthesis of prostaglandin (PGI2) and 12L-hydroxy-5,8,10,14-eicosatetraenoic acid (HETE) by pericardium, pleura, peritoneum and aorta of the rabbit.

Prostacyclin generation by pericardium, pleura, peritoneum, aorta and dura mater of the rabbit was assessed as platelet aggregation inhibitory activity in platelet rich plasma. All tissues except the dura mater, were also incubated with labelled (1-14C) arachidonic acid and (1-14C) prostaglandin endoperoxide H2 and the various metabolites formed were identified radiochromatographically. Pericardium, pleura and peritoneum form substantially high amounts of prostacyclin and HETE indicating that these tissues contain both cyclo-oxygenase and prostacyclin-synthetase. They also show considerable lipoxygenase activity.

Animals↗
PubMed1979

Involvement of SRS-A in the Schultz-Dale response of the guinea-pig small intestine.

1 The anaphylactic reaction of the guinea-pig ileum, the so called Schultz-Dale reaction, shows a biphasic response: a short rapid contraction followed by a partial relaxation and a slow contractile response. 2 Dose-response curves with ovalbumin as an antigen were obtained for the quick and slow contraction of this anaphylactic reaction. 3 Mepyramine (1 microgram/ml) blocked the rapid first contraction, but failed to abolish the slow one in about 50% of the animals studied. 4 The SRS-A antagonist, FPL 55712, significantly depressed the slow sustained contraction during the Schultz-Dale reaction. Disodiumcromoglycate was without effect on both phases when it was added 5 min before addition of the antigen. However, when added simultaneously with the antigen it produced a 30% suppression of the slow phase in the highest concentration used.

Anaphylaxis↗
PubMed1979

The role of thromboxane A2 in endotoxin-induced aggregation of guinea-pig platelets in vitro.

Large concentrations of endotoxin lipopolysaccharides (LPS) E. coli O127:B8 and E. coli O26:B6 were needed for induction of platelet aggregation in citrated platelet rich plasma (PRP) from normal guinea-pigs. When guinea-pigs were actively immunized with LPS E. coli O127:B8 their PRP became more sensitive to the aggregatory effects of this type of LPS. The increase in sensitivity was rather selective since the responses to ADP and LPS E. coli O26:B6 remained unchanged. In endotoxin-stimulated PRP from normal guinea-pigs thromboxane A2 (TXA2) was not detectable by bioassay. Thus biosynthesis of TXA2 seemed to be of little importance in endotoxin-induced platelet responses in normal citrate PRP. LPS E. coli O127:B8, but not LPS E. coli O26:B6, was a potent inducer of the biosynthesis of TXA2 in sensitized PRP. Under those conditions endotoxin-induced aggregation seemed to be dependent on the endogenous biosynthesis of TXA2 by the platelets.

Animals↗
PubMed1978

Effect of prostacyclin on myogenic activity and adrenergic neuroeffector interaction in canine isolated veins.

In isolated strips of canine mesenteric vein prostacyclin (PGI2) causes a dose-dependent depression of the amplitude of the spontaneous rhythmic contractions without influencing their frequency. This suggests that prostacyclin affects the events leading from the depolarization of the smooth muscle cells to their contractions, rather than the induction of the myogenic activity itself. Furthermore, prostacyclin reduces the noradrenaline-induced contraction of the canine saphenous vein without affecting the electrically induced responses, suggesting a possible dual effect of the drug: at the smooth muscle it causes depression of the responsiveness to noradrenaline whereas at the adrenergic nerve endings it enhances the evoked release of the adrenergic transmitter.

Animals↗
PubMed1978

Prostaglandins restore the hyoscine-induced inhibition of the guinea-pig ileum.

Prostaglandins E1, E2 and F2alpha as well as arachidonic acid partially increase the hyoscine inhibited twitch and tetanic responses of the guinea-pig ileum to electrical stimulation. They also produce a shift to the left of the dose-effect curve for acetylcholine and histamine previously displaced to the right by the administration of hyoscine or mepyramine. These results indicate a postsynaptic sensitization effect of the prostaglandins rather than a presynaptic facilitatory activity.

Acetylcholine↗