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Biomedical subjects

J Marsala

Publications and source records attributed to J Marsala.

At least 91 records · Page 5Linked to original sources
PubMed1988

The relation between free and membrane-bound ribosomes in light dorsal root ganglia neurons after aortic ligature in dogs.

To study the relation between free and membrane-bound ribosomes after repeated aortic ligature we examined light dorsal root ganglia (DRG) neurons by quantitative electron microscopy. For counting ribosomes we applied two methods--the hit method and the total counting of ribosomes on electronograms. By both methods we found that there was a prevalence of free ribosomes in DRG neurons on the first and second postoperative day this relation was significantly shifted in favour of free ribosomes which was in agreement with our morphological findings characterized by disaggregation of polysomes and an increasing number of membrane-free ribosomes. At the advanced period of survival (6 days) the studied relation no longer differed from control values. These findings indicate that reorganized proteosynthesis in light DRG neurons plays a most important role during recovery after ischemic insult.

Animals↗
PubMed1987

Axoplasmic transport of monoamine oxidase after ischemia.

Rabbit spinal cords were subjected to 40 min of ischemia by abdominal aorta occlusion followed by 1 or 4 days of recirculation. Axoplasmic transport of mitochondria was investigated by monitoring the accumulation of monoamine oxidase activity (MAO, EC 1.4.3.4) at the proximal and distal ligatures placed on sciatic nerves. Within 1 day following ischemia, MAO accumulation was reduced to 45% and 34% at the proximal and distal ties, respectively. Within 4 days after ischemia, MAO accumulation was depressed still further to 22% in either direction. The substantial decrease in transport velocity appears to be the immediate cause for the observed decrease in MAO accumulation in sciatic nerve.

Animals↗
PubMed1987

Molecular mechanisms of ischemic damage of spinal cord.

Incomplete ischemia of the spinal cord of rabbits was produced by a 40-min occlusion of the abdominal aorta followed by 1 and 4 days of recirculation. Regional evaluation of ATP-induced bioluminescence after 20 min of ischemia revealed ATP depletion mainly in the gray matter of the spinal cord. After 40 min of ischemia, ATP-induced bioluminescence was too faint to expose the photographic film. Within 1 and 4 days of recovery following 40 min of ischemia, restitution of ATP was regionally heterogeneous, reduced predominantly in the anterior horns of gray matter. Polysome profiles remained unaltered during the ischemic period, but a marked disaggregation of polyribosomes occurred after 10 min of recirculation. Protein synthesis in a cell-free system was inhibited by the addition of a postischemic cytosol or protein fraction isolated from cytosols on a DEAE column. The inhibition can be overcome by the addition of each initiation factor 2 (eIF-2), GTP and GDP exchange factor (GEF). Occlusion of abdominal aorta for 40 min results in decrease in monoamine oxidase accumulation in both proximal and distal ligature placed on sciatic nerve. Within 4 days of recovery the transport was progressively depressed to 22 and 21% in the proximal and distal direction, respectively.

Adenosine Triphosphate↗
PubMed1987

Effects of incomplete ischemia and subsequent recirculation on free palmitate, stearate, oleate and arachidonate levels in lumbar and cervical spinal cord of rabbit.

The effect of severe incomplete ischemia, induced by abdominal aorta ligation for 40 minutes, and subsequent recirculation for one and four days on accumulation of free fatty acids was studies in the lumbar and cervical part of rabbit spinal cord. Changes in free fatty acid levels were determined separately in gracile fascicle (Fg), dorsal part (Dp, without Fg) and ventral part (Vp) of both spinal cord regions. In lumbar spinal cord increases in free fatty acid levels, especially that of arachidonate, were observed in Fg, Dp and Vp a the end of the ischemic period. During recirculation all values were similar to nonischemic controls. In cervical spinal cord a slight increase in free fatty acid levels was found in Fg after four days of recirculation, and in Dp arachidonate and stearate levels were most markedly elevated after one day of recirculation. No changes at any interval were found in Vp of cervical spinal cord. The present results indicate that the experimental insult induced typical ischemic injury to spinal cord tissue demonstrated by fatty acid liberation from membrane lipids. This injury may affect neurotransmission and other processes and free fatty acids themselves impair tissue metabolism (inhibition of oxidative phosphorylation, edema precipitation, synthesis of eicosanoids) and thus restrict the possibilities to enhance recovery in the recirculation period.

Animals↗
PubMed1987

The arrangement of endoplasmic reticulum and proteosynthesis in spinal ganglia neurons of dog after ischemia.

The authors studied ultrastructural and biochemical changes in spinal ganglia neurons of dogs after ischemia. Partial spinal cord ischemia was induced by occlusion of the abdominal aorta just below the renal arteries and the arterial blood pressure was registered above and below the occlusion. - In the course of 2-4 hours' ischemia the amount of free ribosomes increased. In some cases the formation of filamentous material or tubular structures inside the cisterns of endoplasmic reticulum was apparent. The proteosynthesis declined. Incorporation of 14C - leucine into the spinal ganglion was 50% as compared to the control animals. The morphological and biochemical changes were more pronounced after 4 h ischemia.

Animals↗
PubMed1987

Effect of local ischemia on catecholamine and 5-hydroxytryptamine levels in the dog brain.

Sixty-minute partial ischemia (occlusion of a. cerebri media dextra) had no such marked effect on changes in monoamine levels as observed after longer intervals. In differentiated parts of area S II (area of direct damage) there was a significant increase of NE in g. sylvius ant. and g. coronarius in comparison to sham-operated controls, a significant elevation of 5-HT in g. sylvius ant. and lesser nonsignificant dopamine changes in area S II. An interesting finding was that in comparison with monoamine levels in sham-operated controls there were changes in their levels also in the contralateral hemisphere of animals with experimentally induced ischemia. In the other areas monitored there were no changes. These results from unilateral partial brain ischemia are corroborated by the findings of other authors at total brain ischemia and indicate that shorter intervals of ischemia produce only slight reversible changes in monoamines whereas longer intervals produce their reduction and impaired metabolism.

Animals↗
PubMed1987

Levels of norepinephrine and 5-hydroxytryptamine in the spinal cord of the dog following ischemia and recirculation.

Forty minutes of abdominal aorta ligature (partial ischemia in the lumbosacral segments of the spinal cord) did not change significantly levels of norepinephrine (NE) and 5-hydroxytryptamine (5-HT) in the spinal cord of the dog in comparison with sham-operated controls. After a 40-minute interval of recirculation NE levels dropped nonsignificantly below levels of the control group and 5-HT significantly in lumbar segments. It thus appears that even though in the stage of recirculation in the spinal cord energy metabolism is restored, the functional deficit of monoamines may persist.

Animals↗
PubMed1986

Influence of blood sera from dogs subjected to ischemia and recirculation on incorporation of 14C-amino acids in vitro.

Incomplete ischemia of the spinal cord was produced in dogs by 40 min occlusion of the abdominal aorta that was followed by 5-40 min of recirculation. Amino acid incorporation into ribosomes in vitro in the presence of venous blood sera was estimated. The most significant reduction in incorporation was produced by sera of the dogs following a short recirculation period (5-10 min). No significant changes were observed at the end of the ischemic period nor at longer periods of recirculation. The decrease in incorporation might be the consequence of inactivation or absence of a substance stimulating polypeptide synthesis in vitro, normally present in blood sera of intact dogs, that temporarily loses its activity during recirculation.

Amino Acids↗
PubMed1986

Arylamidase activity in the rabbit spinal cord after ligation of the abdominal aorta.

Effect of ischaemia, induced by abdominal aorta occlusion, and subsequent survival on the activity of arylamidases was studied in the lumbar and cervical spinal cord of the rabbit. No effect of 40 min ischaemia on the activity of arylamidases was found either in homogenates or in subcellular fractions of the spinal cord. In the lumbar spinal cord a moderate decrease in arylamidase activity was observed after 1 day of survival and a marked decrease was found after 4 days. The decrease were localized in the microsomal and, particularly, in the cytosole fraction. No changes were found in the cervical spinal cord at the corresponding intervals.

Aminopeptidases↗
PubMed1986

Effect of partial ischemia and axotomy on activities of cholinergic enzymes in lower motor neurons of the dog.

Activities of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in the ventral spinal cord, ventral spinal roots and in the central and peripheral stumps of the sciatic nerve transected under conditions of partial ischemia (produced by aortic ligation just below the renal arteries) were compared to those obtained under intact blood supply in time intervals 5, 10, or 15 days after surgery. The significant increase of ChAT activity in the central part of the sciatic nerve following 15 days of partial ischemia correlated with less significant elevation of ChAT in the ventral spinal cord. The changes of AChE activity were not significant during partial ischemia. ChAT in the peripheral stump of the sciatic nerve following 5 days of partial ischemia was preserved by 40% and AChE by 20% more than under normal blood supply. On the contrary, in the next 5 days interval losses of enzymes activity in the degenerating nerve were greater. ChAT was almost totally inactivated whereas 50% of AChE activity was preserved until the end of period examined.

Acetylcholinesterase↗
PubMed1986

Peripheral chromatolysis in spinal ganglia neurons after aortic ligature in dog.

The chromatolytic response of neurons to repeated aortic ligature (2 X 40 min) was studied in lumbar spinal ganglia in dogs with 1, 2, 3 and 6 days survival. The cells were examined by electron microscopy and morphometry. The early changes of endoplasmic reticulum (ER) were characterized by a degranulation of its cisterns and disaggregation of polysomes and resulted in reduction of membrane component remarkable mainly in the peripheral zone of cytoplasm. The chromatolytic neurons were more numerous after a 2 days survival and most of them (60%) showed signs of peripheral chromatolysis. Morphometric analysis revealed a significant decrease in ER area and an increase in its cistern dispersion as well as a reduction of ER membrane component (2 days). Changes of the observed parameters with longer period of survival (6 days) turned to normal level.

Animals↗
PubMed1985

Free amino acids in the spinal cord and ganglia of dogs after ligation of the abdominal aorta.

The authors studied the effect of 40 min and 6 days occlusion of the abdominal aorta on the aspartate [Asp], glutamic acid [Glu], glutamine [Gln], glycine [Gly] and alanine [Ala] concentration in both parts of the grey matter of the lumbosacral cord, in the spinal ganglia and along the dorsal fasciculi. After 40 min ischaemia, an increase was found in the Glu, Gln, Gly and Ala concentration in the dorsal part of the grey matter and in the Glu, Gly and Ala concentration in the spinal ganglia. In the ventral part of the grey matter only the Ala concentration was increased. After 6-day ligation, the Asp and Gly concentration fell in the ventral horns, while the Gly concentration rose in the dorsal horns. The Ala and Asp concentration in the spinal ganglia rose. After this interval the Asp and Glu concentration also rose in the fasciculus gracilis. The Ala/Glu concentration ratio showed the most pronounced increase in the central horns of the grey matter.

Alanine↗