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Biomedical subjects

J Marsala

Publications and source records attributed to J Marsala.

At least 73 records · Page 4Linked to original sources
PubMed1991

Mapping of the canine lumbosacral spinal cord neurons by Nauta method at the end of the early phase of paraplegia induced by ischemia and reperfusion.

The Nauta impregnation method was used to map the neuronal changes in the canine lumbosacral segments following ischemia and reperfusion. The early perikaryal changes ensuing during the first phase after 30 min of thoracic aorta cross-clamping alone or followed by 30 min of reperfusion were mapped. During the second phase (one to six postischemic reperfusion days) the dendritic, preterminal and synaptic degeneration developed. The influence of 30 min cross-clamping immediately followed by perfusion fixation is characterized by the occurrence of flocculent argyrophilic clusters in the cytoplasm of middle-sized and large neurons of L3-S1 segments. Declamping of the thoracic aorta followed by 30 min of reperfusion basically modifies the susceptibility of lumbosacral neurons to Nauta impregnation promoting somatic and dendritic argyrophilia mainly of small (less than 15 microns) neurons, localized mostly in the fifth, sixth and seventh layers, respectively. This early appearing somatic and dendritic argyrophilia is not abolished by a pretreatment of sections with acetone in which cholesterol and its esters are highly soluble, or chloroform-methanol which extracts total lipid. After 24 h of reperfusion the somatic and dendritic argyrophilia is lost but the first signs of drop-like degeneration are detected in all but three superficial dorsal horn layers. At the end of the third reperfusion day, an atypical form of bouton degeneration was found, consisting of massive occurrence of enlarged (greater than 4 microns) boutons encircled by a clear halo. Laminar distribution of enlarged degenerating boutons coincides with laminar quantitative distribution of small argyrophilic neurons detected 30 min after reperfusion. The basic orientation of the many terminal fibres attached to enlarged boutons suggests that they belong to the axons localized mainly in the lateral and anterior columns. Despite a dense argyrophilic network pervading the gray matter of lumbosacral segments only pale shadows of middle-sized and large neurons were found at the end of the sixth reperfusion day and neither somatic nor vessel wall argyrophilia could be detected. All animals surviving one, three and six days postoperatively suffered from fully developed paraplegia.

Animals↗
PubMed1991

Graded postischemic reoxygenation ameliorates inhibition of cerebral cortical protein synthesis in dogs.

The purpose of this study was to determine the effect of normoxic reperfusion and graded postischemic reoxygenation on cerebral protein synthesis in a cell-free system. Ischemia alone produced a relatively small decrease (15-17%) in activity in all the subcellular systems studied. After a 15-min interval of normoxic reperfusion (75-90 mmHg O2 in arterial blood), a 40% decrease (p less than 0.01) in [14C]leucine incorporation was observed. Reoxygenation with hypoxemic blood containing 37.5 mm Hg O2 at 0-5 min and 56 mm Hg O2 at 6-10 min of recirculation followed by 5 min of normoxic reperfusion resulted in a significant increase (p less than 0.05) of polypeptide chain synthesis in vitro when compared with normoxic reperfusion. The results obtained by this experimental approach tend to show that graded postischemic reoxygenation could be used as a simple and effective neuroprotective tool that substantially diminishes the secondary postischemic damage in nervous tissue, including the newly synthesized proteins.

Animals↗
PubMed1990

Postischemic hypoxia improves metabolic and functional recovery of the spinal cord.

We studied the effect of graded postischemic reoxygenation on the tissue concentrations of adenylates, glucose, and lactate in the rabbit lumbar spinal cord after 10, 20, and 30 minutes of ischemia. In comparison with recirculation without manipulated PaO2, a decrease of PaO2 to 40 to 45 mm Hg upon reestablishment of blood circulation after ischemia led to an amelioration of the energy metabolism in the spinal cord tissue as determined by measuring the ATP concentration and energy charge. The protective effect of postischemic hypoxia was also reflected by the improvement of neurologic functions in animals after 10 and 20 minutes of ischemia.

Adenosine Triphosphate↗
PubMed1990

Effect of severe incomplete ischaemia and postischaemic reperfusion on phospholipids and unesterified cholesterol in rabbit spinal cord.

Effect of severe incomplete ischemia, induced by occlusion of the abdominal aorta caudal to the left renal artery for 40 min, and postischemic reperfusion for 6 h, 1 and 4 days on phospholipid composition and unesterified cholesterol concentration was studied in the lumbosacral (L3-S1) spinal cord separated into the gracile fascicle (Fg), dorsal part without Fg (Dp) and ventral part (Vp). Ischemia decreased the inositol phospholipid (PI) concentration in Dp and Vp and this was recovered during reperfusion. Within 6 h following ischemia, ethanolamine (PE) and serine (PS) phospholipid concentrations decreased in Dp and PS also in Vp. During the long reperfusion intervals the concentrations of the two major phospholipids, PE and choline phospholipid (PC) declined in Fg, Dp and Vp. No changes were observed in sphingomyelin (SM). The concentration of unesterified cholesterol (UC) was lower throughout the reperfusion period in Dp and Vp, while the decrease in Fg was delayed. The molar ratio UC/TPL was reduced starting from 24 h of reperfusion. The pattern of changes, which were delayed in the white matter as compared to Dp and Vp (containing the gray matter) indicated severe damage to the membrane structures in the tissue, developed during reoxygenation, that was related to decreased tissue viability.

Animals↗
PubMed1989

Early neurohistopathological changes of canine lumbosacral spinal cord segments in ischemia-reperfusion-induced paraplegia.

Mapping the canine lumbosacral spinal cord neurons damaged by ischemia-reperfusion after high thoracic aorta ligation was performed using the Nauta degenerating method. Highly Nauta-positive perikarya of the long ascending projection systems in the 4th to 6th dorsal layer, interneurons in the 7th layer and motoneurons in the 8th and 9th layers in L3-S3 segments subjected to 30 min of ischemia and 30 min of reperfusion were localized and their laminar distribution was specified. Spastic paraplegia fully developed 2 days postoperatively after 30 min of aortic ligation is neurohistopathologically characterized by occurrence of enlarged Nauta-positive boutons with prevailing localization in the 4th to 8th layer of the gray matter.

Animals↗
PubMed1989

Effect of spinal cord ischemia on axonal transport of cholinergic enzymes in rabbit sciatic nerve.

The fast axonal transport of acetylcholinesterase (AChE) and the slow transport of choline acetyltransferase (ChAT) were measured by the stop-flow ligation technique in the sciatic nerve of rabbits 6 and 24 h after ischemia performed by the occlusion of the abdominal aorta which lasted 40 min. Activities of these enzymes were also measured in punched samples of the spinal cord (L5-6). Results were correlated with those obtained from the sham-operated control group. Six h after ischemia, its only apparent effect was a different distribution of accumulated enzymes in the central nerve segments. Twenty-four h after ischemia, the transport of AChE was markedly depressed; proximodistal accumulation decreased by 68%, whereas enzyme activity in the intact contralateral nerve and in the ventral horns of the spinal cord was preserved. No effect of ischemia on the retrograde axonal transport of AChE was observed in this experimental model. Cytoplasmic ChAT is much more susceptible to necrotic degeneration than membrane-bound AChE; 24 h after ischemia its activity decreased significantly in all investigated parts of the sciatic motoneurones but the rate of slow axonal transport did not seem to be affected.

Acetylcholinesterase↗
PubMed1989

Effect of partial ischemia on phospholipids and postischemic lipid peroxidation in rabbit spinal cord.

Rabbit spinal cord, subjected to severe partial ischemia induced by abdominal aorta ligation tightly below the renal arteries, was analyzed for phospholipid composition and levels of lipid peroxidation products after 10, 20, and 40 min of the insult. Under conditions when spinal cord blood flow was decreased below 5% of control, concentrations of inositol and ethanolamine phospholipids were decreased by 30% and 10%, respectively. Phosphatidic acid concentration was also altered during ischemia. No accumulation of thiobarbituric acid reactive substances (TBA-RS), conjugated dienes and fluorescent lipid soluble material was found throughout the ischemic period. Pattern of TBA-RS, conjugated diene, and fluorophore formation during postischemic in vitro incubation without and with a peroxidation couple (Fe2+, ascorbic acid) showed increased susceptibility to postischemic lipid peroxidation in tissues after 20 and 40 min of ischemia.

Animals↗
PubMed1989

Improvement of energy state and basic modifications of neuropathological damage in rabbits as a result of graded postischemic spinal cord reoxygenation.

The role of graded postischemic reoxygenation applied at the end of 20 min of spinal cord ischemia was studied with respect to the intraspinal pO2 tension, energy state, and histopathological sequelae. Graded postischemic reoxygenation can induce a positive shift in the intraspinal pO2 tension, but normal postischemic reoxygenation with normotensive pO2 blood tension inevitably causes the postischemic intraspinal pO2 overshoot. Graded postischemic reoxygenation significantly improves the energy state expressed by higher adenosine triphosphate (ATP), phosphocreatine (PCr) and glucose levels. Using the Nauta impregnating degenerating method, clear histopathological differences were found in the L3-S3 segments after 20 min of ischemia. Apparently divergent damage was observed when normal reoxygenation or graded postischemic reoxygenation was used. Diametrically different histopathological outcomes were obtained with normal reoxygenation and graded postischemic reoxygenation 2 and 4 days postoperatively.

Animals↗
PubMed1989

Regional concentrations of transmitter amino acids after spinal cord ischaemia in the rabbit.

Concentrations of Asp, Glu, Gly, GABA and Gln were studied in the ventral and dorsal horns of the rabbit spinal cord after ligation of the abdominal aorta. The most significant changes observed after 10, 20 and 40 min ischaemia were an increase in the Asp and GABA concentration in the ventral horns and an increase in the Asp, Gly and GABA concentration in the dorsal horns. These changes correspond to shifts in the relevant reactions under conditions of the altered redox equilibrium in the tissue during ischaemia. Four days after 10 min ischaemia, amino acid concentrations in the spinal cord were at the control levels. Four days after 20 and 40 min ischaemia Asp, Gly and GABA concentrations were decreased in the ventral horns and Asp, Gly, GABA and Glu concentrations in the dorsal horns. The percentually greater decrease in the concentration in the ventral horns may be associated with the greater morphological damage to these structures.

Amino Acids↗
PubMed1989

[Transplantation of embryonic brain tissue into newborn rats after unilateral bulbectomy].

Embryonic tissue (E14-E16) of the olfactory bulb and substantia nigra resp. was transplanted to neonatal rats into cavities formed by partial or total unilateral bulbectomy. After 40 days of survival the animals were perfused with Bouin's fluid and processed for histological examination. Complete series of 10 microns horizontal or sagittal sections were stained with Gill haematoxylin and Bodian's silver method. To demonstrate the olfactory protein immunohistochemical staining with peroxidase-antiperoxidase was used. After bulbectomy degeneration of the axons of the olfactory cells occur, which subsequently regenerate, penetrate into the transplant and form typical glomerular structures in the latter. By immunohistochemical staining in both types of transplants olfactory structures were reliably differentiated from non-olfactory elements.

Animals↗
PubMed1989

[Experimental model of ischemic injury of the spinal cord after temporary occlusion of the thoracic artery in the dog].

An experimental model for the ischemic damage of the spinal marrow is described by occlusion of the descending thoracic aorta at a level with the 5th or 6th thoracic vertebrae during 30 min. 17 dogs were operated in general anesthesia. The thoracic aorta was clamped by a Pean's clamp in the 1st group (11 animals). One dog was not paralysed, another dog died after thrombosis of the aorta in the locality of clamping. The occlusion was carried out by means of a tourniquet in a 2nd group (6 animals) and pH, blood gas values, and blood pressure in the axillary artery or the common carotid artery were measured. An increase of the blood pressure above the initial value was prevented by slow infusion of nitroprusside. The oxygen pressure in the spinal marrow tissue was measured continuously simultaneously. All these animals survived the operation and a complete damage of the spinal marrow occurred.

Animals↗
PubMed1989

[Experimental implantation of peripheral nerves in cerebral hemispheres of rabbits].

The authors give a report on the results obtained in the implantation of autologous nerves in the cerebral hemispheres of rabbits. In a group of five rabbits they implanted a nerve immediately after its removal, in a second equally large group they implanted a nerve only after seven days of preliminary degeneration. After 12 to 14 weeks of the animals with 10 per cent neutral formalin was carried out and the preparations were impregnated according to the Nauta-Gygax method. In the histological sections they only succeeded in discovering individual fibres, which may be the axons of the cerebral cells growing through into the transplanted peripheral nerves. The authors did not see any differences between the immediately implanted nerves and nerves only implanted after a preliminary degeneration. The results obtained require a maximum of caution in the appraisal of the transplantation possibilities in the central nervous system.

Animals↗
PubMed1989

Spinal ascending projections to the nucleus tractus spinalis nervi trigemini of the dog.

Seven dogs were subjected 30 min to ligation of the thoracic aorta and were then kept alive 6-7 days after the ligature had been removed. Their spinal cord and brain stem were treated by the Nauta-Gygax method and the extent and appearance of preterminal and terminal degeneration of certain ascending spinal systems were analysed. In the medulla oblongata region, marked degenerating fibres from the lower thoracic and lumbosacral cord segments were found in the nucleus tractus spinalis nervi trigemini. Preterminal and terminal degenerating fibres were visualized in the caudal part of the trigeminal nuclear complex. Comparison with the literature showed these to be previously unknown projections with a relationship to the nucleus tractus spinalis nervi trigemini.

Animals↗
PubMed1989

Changes in nucleus tractus spinalis nervi trigemini after temporary occlusion of aorta thoracica in dog.

In a group of seven dogs the thoracic aorta was occluded by means of tourniquet for 30 minutes. After the release of aorta the animals were left living for 6-7 days. The spinal cord and brain stem were treated by Nauta-Gygax method after sacrificing the animals, then the preterminal and terminal degenerations of some ascending spinal systems were analysed. Distinct degenerations in nucleus tractus spinalis nervi trigemini were detected. They originated in lower thoracic and lumbosacral segments of spinal cord. Degenerations were localised in the caudal part of nuclei of trigeminal complex. It looks like the above mentioned projections terminating in nucleus tractus spinalis nervi trigemini are related to tractus spinocerebellaris posterior.

Afferent Pathways↗
PubMed1988

[Laminectomy in the dog for experimental purposes--a technical comment].

The reach of the lumbar vertebral column in the dog should be preferred in operations on the spinal marrow after own experiments. A better survey during the operation and a smaller risk of contusion of the spinal marrow by surgical instruments passed through there by reason a wider spinal canal a more voluminous spinal marrow. This method is more expensive, however more advantageous than a laminectomy in the reach of the thoracic spine because there exist some differences in the form of the bodies of the vertebra in humans and dogs.

Animals↗