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Biomedical subjects

B J Mrsulja

Publications and source records attributed to B J Mrsulja.

At least 19 recordsLinked to original sources
PubMed1985

Ultracytochemical localization of ouabain-sensitive K+-dependent, p-nitrophenyl phosphatase in myelin.

Ouabain-sensitive, K+-dependent p-nitrophenyl phosphatase (K-NPPase) activity was demonstrated ultracytochemically in the myelin of nerve fibers in peripheral and central white matter. Enzyme activity was more prominent in paranodal than compact myelin, and it was absent from nodal and interparanodal axolemma. Since K-NPPase is part of the Na-KATPase complex, we consider myelin as an important site of the sodium pump and believe that myelin participates in cationic regulation of the nervous tissue.

4-Nitrophenylphosphatase↗
PubMed1984

Histochemical localization of gamma glutamyl transpeptidase in the paranodal region of peripheral nerve.

Gamma glutamyl transpeptidase (GGT), an amino acid transport enzyme, was investigated in normal and degenerated sciatic nerve of rat. The enzyme activity, which is considered to be a marker for cerebrovascular endothelium, was found to be absent in microvessels of normal and degenerated nerves. In the perineurium of normal nerve, GGT activity was faint, while in degenerated nerve, it increased. The most striking finding of this study was the observation of GGT activity at the paranode of each normal myelinated axon. It is interesting that after axotomy (8 weeks), no GGT activity was observed in the Schwann cells of degenerated nerve. Thus, Schwann cell plasmalemma contributed to GGT staining only when this cell was in contact with an axon mature enough to cause it to produce myelin. We conclude that, in peripheral nerve, transmembrane amino acid transport is apparently regional and associated with the paranodal region of myelinated nerve fibers.

Animals↗
PubMed1980

Monoamines and related enzymes in cerebral cortex and basal ganglia following transient ischemia in gerbils.

The post-ischemic effects on cerebral cortex and basal ganglia monoamine levels and monoamine oxidase (MAO A and B) and catechol-O-methyl transferase (COMT) activities were evaluated in Mongolian gerbils (Meriones unguiculatus) subjected to bilateral common carotid arteries of occlusion for 15 min and reflow for 7 days. Disorders of monoamine metabolism was found in ischemic brain which persisted during the long-term post-ischemia. A rebound increase of norepinephrine and serotonin appeared in early stages (up to 1 h) of post-ischemia both in cerebral cortex and basal ganglia; a rebound increase of dopamine as found only in cerebral cortex. Thereafter, the serotonin level ws enhanced over the control level during the whole post-ischemic period whereas the levels of catecholamines were reduced particularly in basal ganglia. With respect to monoamine content and activities of monoamine degraded enzymes an oscillatory behavior was observed in the post-ischemia. Disorder of the monoamine metabolism found during post-ischemic period possibly contributes to neurological dysfunction after an ischemic insult.

Animals↗
PubMed1979

Histochemical investigation of the Mongolian gerbil's brain during unilateral ischemia.

The ischemic effect on cerebral enzymes and glycogen content was histochemically evaluated in mongolian gerbils subjected to unilateral common carotid artery occlusion for various periods of time from 1/2 to 9 h. In early stages (up to 2 h), the only enzyme affected was the phosphorylase which revealed a decreased activity. Thereafter, the observed changes inclusive of glycogen and other enzymes such as the dehydrogenase, nonspecific acid and alkaline phosphatases, leucine aminopeptidase and thiamine pyrophosphatase progressed proportionally to the duration of ischemia. There was an overall inverse appearance of histochemically demonstrated enzymatic disturbances between the severely damaged ischemic regions and its marginal zones; the former revealing a conspicuous decrease and/or loss of enzymatic activities while the latter showing an increase of the same enzymes. Correlating the various ischemic responses of the intracellular organelles it appears that the changes in the lysosomes and Golgi apparatus occurred slower than those of mitochondria.

Acid Phosphatase↗
PubMed1978

Alterations of putative neurotransmitters and enzymes during ischemia in gerbil cerebral cortex.

Bilateral occlusion of common carotid arteries in Mongolian gerbils was produced for the periods (up to 15 min) which were shown to be totally reversible. There was an initial increase of cyclic AMP and GABA levels and enhanced activities of adenylate cyclase and glutamate decarboxylase, as well as the reduction of norepinephrine level and decreased activities of monoamine oxidase, GABA-transaminase and Na+-K+-ATPase. Following these changes, decreased concentration of dopamine, serotinin and glutamate were found. The activities of total protein kinase and acetylcholinesterase were found to be reduced after longer periods of short-term ischemia. The data are consistent with the concept of increased non-controled release of putative neurotransmitters in ischemia.

Adenylyl Cyclases↗
PubMed1976

Experimental cerebral ischemia in Mongolian gerbils. v. Ultrastructural changes in H3 sector of the hippocampus.

Mongolian gerbils exposed to relatively short (7 or 15 min) unilateral or bilateral occlusions of the common carotid artery develop, 20 h after release of the clipping, characteristic morphologic changes in the H3 sector of the hippocampus. Ultrastructural study of these changes revealed an eccentric shift of the nuclei associated with chromatolytic perikarya which showed a dense accumulation of lysosomes and mitochondria in their central parts. The Golgi apparatus was recognizable only by clusters of vesicles, and this change was associated with a negative thiamine pyrophosphatase reaction.

Animals↗
PubMed1976

Experimental cerebral ischemia in Mongolian gerbils. IV. Behaviour of biogenic amines.

Behaviour of biogenic amines was studied in the brains of Mongolian gerbils subjected to unilateral occlusion of the common carotid artery. Assays on the hemispheres ipsilateral to occlusion revealed in symptom-positive animals a progressive decrease in norepinephrine and dopamine, and an increase in serotonin throughout the duration of an ischemic insult. In post-ischemic periods following the release of the clip, changes in biogenic amine levels generally conformed to the principles of a previously described "maturation" phenomenon, with delayed reactions occurring after the shorter ischemic insults.

Animals↗
PubMed1976

Brain serotonin after experimental vascular occlusion.

Unilateral ligation of a common carotid artery in gerbils causes a decreased rate of serotonin synthesis and degradation but an increased release of this monoamine. In the brain, reduction of cerebral serotonin content during ischemia is followed by accumulation of its main metabolite, 5-hydroxyindolacetic acid. These data support the contention that serotonin plays an important role in the progression of cerebral infarction.

Animals↗
PubMed1975

Experimental cerebral ischemia in Mongolian gerbils. II. Changes in carbohydrates.

A cerebral ischemia was produced by unilateral ligation of the common carotid artery in the neck of Mongolian gerbils (Meriones unguiculatus), which are frequently characterized by deficiencies in the circulus of Willis. Concentrations of glucose, lactate, pyruvate and glycogen were measured in the hemisphere on the side of occlusion and in the contralateral control hemisphere of animals sacrificed after 5, 15 and 30 min, as well as after 1,3,5 and 9 hrs of carotid clamping. Significant decrease of glucose, and increase in lactate and pyruvate concentration were found in the hemisphere ipsilateral to occlusion; the extent of the changes was proportional to the duration of the ischemia. After an initial fall, an increase in the glycogen content occurred in the later stages of ischemia. Glycogen, glucose, lactate and pyruvate were determined also at 1, 5, 20 hrs and 1 week intervals following release of an occlusion lasting for 1 hr. Return to normal values of glucose and pyruvate was seen at 1 hr after release. The lactate and glycogen levels were significantly raised on the occluded side after 20 hrs release. An increased level of glycogen was observed as long as 1 week after a 1-hr carotid occlusion.

Animals↗