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Biomedical subjects

H E Hirsch

Publications and source records attributed to H E Hirsch.

At least 19 recordsLinked to original sources
PubMed1983

Na+- and K+-dependent adenosine triphosphatase changes in multiple sclerosis plaques.

Na+- and K+-dependent adenosine triphosphatase [(Na+ + K+)-ATPase] was studied in microdissected samples from sections of histologically active and inactive plaques of multiple sclerosis. In active plaques the enzyme was found to be markedly reduced in activity, whereas in old, chronic plaques ATPase activities were higher than those of unaffected white matter. White matter from control patients and normal-appearing white matter from MS patients did not differ with regard to ATPase activities. The results suggest that reversible changes in the sodium pump mechanism may be involved in the pathophysiology of multiple sclerosis.

Brain↗
PubMed1982

The ratio of 3-hydroxyacyl-CoA dehydrogenase to lipoamide dehydrogenase activity in individual muscle fibers: mitochondrial specialization for source of energy.

3-Hydroxyacyl-CoA dehydrogenase (HAD) has been widely used to assess the capacity for fatty acid oxidation by different muscle fiber types, with various Krebs cycle enzymes as a base for comparison. We have measured this enzyme in individual lyophilized fibers of the guinea pig soleus and the white and red portions of the vastus lateralis, and compared its activity in each fiber with that of lipoamide dehydrogenase (LAD), which as a part of the pyruvate dehydrogenase complex fulfills a function similar to HAD in forming acetyl-CoA, but from pyruvate and, thus, mainly from a carbohydrate source. The mean HAD/LAD ratio was 17.2 +/- 3 in the red vastus, 24.9 +/- 3 in the white vastus, and 43.7 +/- 10 in the soleus, all differences being highly significant. The two types of fast fibers were not distinguished from one another by the enzyme ratio within either the white or the red portion of the vastus lateralis. Data from all of the fast fibers taken together indicate a close correlation (0.93) between the two enzymes, whereas values from the soleus indicate a specialization of the mitochondria of the slow muscle fibers for the oxidation of fatty acids.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1981

Fibrinolytic activity of plaques and white matter in multiple sclerosis.

Recent work has implicated plasminogen activator released from macrophages as a possible mediator of the demyelinating process in experimental allergic encephalomyelitis and multiple sclerosis (MS). We have studied the capacity of white matter and plaques from MS patients to break down fibrin clots, using a histochemical technique. Fibrinolytic activity was localized exclusively to areas around blood vessels and capillaries in both patients and controls. While there was marked variation between individuals, the unaffected white matter from MS patients was, on the average, not more active than that of controls, but plaques tended to show more numerous foci of lysis, often also more intense, than adjacent white matter; there was no correlation with disease activity or age of the plaques as determined by histological criteria. The localization and degree of fibrinolysis observed were not related to the presence of lymphocytic infiltrates, gliosis, or macrophages. However, the findings do not exclude an involvement of fibrinolytic enzymes (although originating from vascular endothelium rather than macrophages) in the genesis of the MS plaque, which commonly starts around a small vein.

Brain↗
PubMed1980

Partition coefficients of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO0 in erythrocyte lipids in multiple sclerosis.

Electron spin resonance (ESR) was used in a search for a possible generalized membrane defect underlying myelin instability in multiple sclerosis (MS). In contrast to most ESR studies of biological membranes, a small, nonelectrolyte spin label, TEMPO, was chosen; its partition coefficient was determined in extracted erythrocyte lipids from MS patients and normal controls. No differences were observed the advantages and limitations of TEMPO in comparison with lipid spin labels as probes for the study of biological membranes are discussed.

Cyclic N-Oxides↗
PubMed1976

[Mono- or biphasic release of gastrin. Results after isolated antrum perfusion in vitro].

In an in vivo preparation, isolated rat antra were perfused with different releasing agents in an oxygenated Krebs-Ringer-A solution. Upon perfusion with acetylcholine (+ 0,1 mM eserine), the mean gastrin levels in the effluent increased within 2 min to 4 times the basal level, while there was a smaller second release after 20 min. During perfusion with 50 mM glycine and 30 mM calcium chloride containing Krebs-Ringer-A solution gastrin levels in the effluent increased within 4 min to twice the basal level without a secondary release of gastrin. Perfusion with eserine alone or with Krebs-Ringer-A solution failed to release gastrin. The apparent biphasic release of gastrin with acetylcholine may suggest that antral gastrin may exist in two different populations, one of which is readily accessible, the other less so. Alternatively, the initial peak may consist only of stored gastrin and the second peak of newly synthesized gastrin, stimulated only by the physiologic stimulus of acetylcholine, and not by other releasers.

Acetylcholine↗
PubMed1975

[Mechanism for the liberation of duodenal gastrin in the dog].

The mechanisms of duodenal gastrin release were studied in 13 mongrel dogs after selective mucosal antrectomy: Vagal stimulation with insulin and local perfusion with acetylcholine at pH 7 resulted in a significant increase of the serum gastrin level taken from the pancreatico-duodenal vein. No significant amounts were detected after vagal stimulation with 2-deoxy-d-glucose, local perfusion with acetylcholin at pH 1, 5 nor after duodenal distension with 20, 40 and 120 cm water.

Acetylcholine↗