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Biomedical subjects

M Viola

Publications and source records attributed to M Viola.

At least 55 records · Page 3Linked to original sources
PubMed1989

Intracellular transport and neuronal activation of phospholipid and glycoprotein synthesis during axonal regeneration of cranio-spinal nerves.

In the present work, the hypothesis that the increased rapid intracellular transport of newly-synthesized material along the axons of a regenerating system is sustained by an alteration of the transport of proteolipid complexes through subcellular compartments of a neuronal cell body was tested by a biochemical methodology. The motoneurons of spinal cord ventral horn, 4 wk after unilateral lesion (crush) of cervico-thoracic nerves of the rabbit at the level of brachial plexus, were chosen as the model system of regeneration. A time-staggered procedure of in vivo and in vitro double labeling with metabolic precursors, such as [3H]-choline, [14C]-choline, [3H]-fucose, and [14C]-fucose, was used. Subcellular fractions (RER, SER, Golgi apparatus, and plasma membranes) of ventral horn tissue, taken from spinal cord hemisections (regenerating and contralateral side), were further isolated. Twenty-eight days after axotomy, we did not observe any change of intracellular transport kinetics (14C/3H ratio) of newly-synthesized choline-phospholipids and glycoproteins in regenerating motoneurons compared to controls. However, associated with regenerating phenomenon in Golgi apparatus, we observed an increase of labeled choline-phospholipid and glycoprotein material that could contribute to the increased fast axonal transport and delivery of membrane proteolipid complexes to plasma membrane and axonal compartments. The increase of glycoprotein labeling was more pronounced in the SER portion (vesicles and elements of smooth membranes). This result is in favor of the hypothesis that membrane-bound proteins are transported from the Golgi to the axon through the perikaryal SER.

Animals↗
PubMed1989

Region-selective decline of in vivo lipid synthesis in the aged rat visual system.

[14C]palmitate and [3H]choline were injected intravitreally and, at the same time, intraventricularly in Wistar male rats at 4, 10, and 24 mo of age. The precursor incorporation into lipids of the retina, optic nerve tract, superior colliculus, and lateral geniculate body was followed for 2 h. The specific radioactivity of precursors pool (choline, phosphorylcholine, and free fatty acids) showed a marked decrease in optic nerve tract and lateral geniculate body of aged rats, whereas in retinal tissue and superior colliculus no changes were observed as a function of age. In rats of the three age groups, whole retina and superior colliculus showed neither changes of choline incorporation into phosphatidylcholine and sphingomyelin nor alteration of palmitate incorporation into diacylglycerols, triacylglycerols, and major phospholipid classes as a function of age. In sharp contrast, the optic nerve tract and, to a lesser extent, the lateral geniculate body exhibited a significant age-related decline of either the incorporation of both precursors into all lipid classes or the specific radioactivities of endogenous precursor pools. We concluded that the visual pathway structures are metabolically affected in a different manner by aging. Particularly, the ability of the retina and superior colliculus to metabolize lipids appeared to be age invariant. The marked decline of lipid biosynthesis with age, for some visual structures, is consistent with the trend generally observed in metabolic turnover and function of other CNS regions.

Aging↗
PubMed1988

Age-related changes of RNA and lipid synthesis in vitro by retina and optic nerve of the rat.

We examined the effects of age on RNA and lipid formation by whole retina and optic nerve in vitro. Male Wistar rats, aged 4, 12, and 24 mo, were used. From the results obtained the following conclusions may be drawn: 1. In assaying the lipid biosynthesis during aging, a striking difference between the retina and optic nerve clearly emerged; 2. In isolated retina, [3H]uridine incorporation into RNA was relatively constant at the three ages, whereas both [14C]palmitate and [3H]choline incorporation into lipids showed a substantial increase in rats at 24 mo of age compared with those at 4 mo; 3. In contrast, in the optic nerve of the oldest rats, compared with the youngest, a significant decrease of [14C]acetate and [14C]palmitate incorporation into acylglycerols, cerebrosides, and phospholipids was found. Each fatty acid precursor label was incorporated to a proportion that reflected the typical acyl group composition of individual lipids; 4. Following labeling of the optic nerve with [3H]choline, the specific radioactivity of choline-containing phospholipids was drastically decreased with increasing rat age; and 5. The incorporation of [2-3H]glycerol into optic nerve diacylglycerols, PtdEtn, and PtdIns declined with age, whereas no significant change took place in the incorporation into PtdCho. The results strongly support the concept that RNA metabolism of rat retina (most likely photoreceptor cell layer) is not altered during aging; on the contrary, phospholipid synthesis is stimulated in comparison with that of the optic nerve, for which a serious impairment was concomitantly observed. The physiological significance of these responses, and the mechanism by which retinal tissue is spared from the general age derangement of the nervous system, remain to be defined.

Aging↗
PubMed1985

Synthesis of myelin proteins and ultrastructural investigations in regenerating rat sciatic nerve.

Myelin protein synthesis, as well as ultrastructural and morphometric changes in regenerating peripheral nerve, was studied. Sciatic nerves of rats were crushed unilaterally; sham-operated nerves of the contralateral side served as controls. For the in vivo experiments, rats were killed at selected periods after the nerves were crushed (30, 60, 90, and 120 days); seven days prior to killing, the animals were injected intravenously with L-[4,5-3H]leucine. For the in vitro experiments, proximal and distal segments of sciatic nerve and equivalent sham-operated nerves were labeled with 3H-amino acid mixture 90 days after axotomy. Purified myelin was isolated from nerve segments; specific radioactivity and gel electrophoretic patterns of proteins were analyzed. Cross-sectional electron microscope (EM) preparations of proximal, distal, and contralateral segments of nerves also were examined. Results showed that the incorporation of labeled amino acids into total myelin proteins was enhanced significantly in the distal segment of sciatic nerves at all of the periods of regeneration studied. The yield of myelin protein per mm distal nerve segment increased as regeneration proceeded. The remyelination of fibers early after nerve crush was weak, whereas it gradually attained the normal range 90-120 days after axotomy. Morphometric analysis of myelin sheath thickness of regenerating axons was consistent with the data obtained for myelin protein synthesis.

Animals↗
PubMed1985

Remodeling and sorting process of ethanolamine and choline glycerophospholipids during their axonal transport in the rabbit optic pathway.

The existence of a mechanism by which the ester- and ether-linked aliphatic chains of the major phospholipids are retailored during their axonal transport and sorted to specific membrane systems along the optic nerve and tract was investigated. A mixture of [1-14C]hexadecanol and [3H]arachidonic acid was injected into the vitreous body of albino rabbits. At 24 h and 8 days later, the distribution (as measured by the 3H/14C ratio) and the positioning (as monitored by hydrolytic procedures) of radioactivity in the various phospholipid classes of retina, purified axons, and myelin of the optic nerve and tract were determined. At the two intervals after labeling, the 3H/14C ratios of each diradyl type of phosphatidylethanolamine and phosphatidylcholine were (a) substantially unchanged all along the axons within the optic nerve and tract and (b) markedly modified in comparison with those found in the retina and axons for molecular species selectively restricted to myelin sheath. Evidence is thus available that intraxonally moving ethanolamine and choline glycerophospholipids, among others, are added to axonal membranes most likely without extensive modifications. In contrast, they are transferred into myelin after retailoring. Through these two processes, the sorting and targeting of newly synthesized phospholipids to their correct membrane domains, such as axoplasmic organelles, axolemma, or periaxonal myelin, could be controlled.

Animals↗
PubMed1984

Myelination process in the rat sciatic nerve during regeneration and development: molecular species composition and acyl group biosynthesis of choline-, ethanolamine-, and serine-glycerophospholipids of myelin fractions.

The content of alkenyl-acyl, alkyl-acyl and diacyl types of the three major myelin glycerophospholipids such as PtdCho, PtdEtn and PtdSer was determined in myelin fractions prepared from sciatic nerve segments of rats at 12, 25 and 45 days after birth, and of adult rats (6-month-old) 90 days after crush injury. The biosynthesis and metabolic heterogeneity of lipid classes and types were also studied by incubation with [1-14C] acetate of nerve segments of young rats at different ages as well as crushed and sham-operated control nerve segments of adult rats. The analysis of composition and positional distribution in major individual molecular species extracted from light myelin and myelin-related fraction suggest that the metabolism of alkenyl-acyl-glycerophosphorylethanolamines and unsaturated species of PtdCho and PtdSer may not be regulated in the same manner during peripheral nerve myelination of developing rat and remyelination of regenerating nerve in the adult animal. The 14C-radioactivity incorporation into lipid classes and alkyl and acyl moieties of the three major phospholipids of sciatic nerve segments during the developmental period investigated revealed that Schwann cells were capable of synthesizing acyl-linked fatty acids in both myelin fractions at a decreasing rate and with different patterns during development. In regenerating sciatic nerve of adult animals the labeling of myelin lipid classes and types of remyelinating nerve segment distal to the crush site was markedly higher than that of sham-operated normal one; however, the magnitude and the pattern of the specific radioactivity never approached those observed during active myelination of the nerve in young animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1983

Axonal transport of glycerophospholipids in regenerating sciatic nerve of the rat during aging.

The effect of age upon the axoplasmic transport of glycerophospholipids has been studied using as a model the regenerating sciatic nerve of young (2-month-old), young adult (6-month-old), middle-aged (16-month-old), and aged (20-month-old) male rats. The right sciatic nerve was crushed 0.5 mm down the incisura ischiadica. Four and nine days after the lesion, a mixture of [2-3H] glycerol and [methyl-14C] choline was bilaterally injected into the spinal cord, at a level of the L4-L5 vertebrae. The animals were killed 18 hr after the isotope injection. Proximal and distal portions of crushed nerve and of contralateral sham-operated ones were dissected and consecutive 5-mm segments were subjected to lipid extraction and analysis. The findings of the present study are summarized as follows: (1) The accumulation of labeled lipid material axonally transported four days after nerve injury was mainly located at the crush site in young, young adult, middle-aged, and aged rats. The accumulation of both 3H-glycerolipids and 14C-choline phospholipids in postcrush segments was markedly higher for young and young adult than for aged rats, four and nine days after crush; (2) the average rate of axonal regeneration, determined between days 4 and 9 following crush injury was 3.6 and 4.2 mm/day for 2-month-old and 6-month-old rats, respectively; it decreased to the value of 2.5 mm/day for 16-20-month-old rats.

Aging↗
PubMed1983

Myelination of regenerating sciatic nerve of the rat: lipid components and synthesis of myelin lipids.

Changes of lipid, free fatty acid, protein, DNA, and RNA content in proximal and distal segments of regenerating sciatic nerve, from 14 to 120 days after crush, were determined. During the early stage of Wallerian degeneration, a marked decrease of phospholipid, cerebroside and sulfatide content and, in contrast, a marked increase of protein, DNA, RNA, and free fatty acid content, in the distal segment of crushed nerve compared to control, was observed. A gradual increase of phospholipid, cerebroside, and sulfatide levels, approaching normal values, and a gradual slope in the increase of protein, DNA, RNA, and free fatty acid levels over the ensuing time periods of regeneration was seen. Total cholesterol content was relatively constant during regeneration, slightly increasing at day 120. The activity of 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) of myelin fraction purified from distal segment of regenerating sciatic nerve showed a significant increase in the 30-120 day regenerating period. A marked increase of the incorporation of [2-3H]glycerol and of [Me-14C]choline into myelin lipids of distal segment of regenerating nerve, was found. Labeling of myelin lipids with [3H]oleic acid (injected intravenously seven days before crush) support the evidence that a similar pattern of degeneration exists between two different types of trauma, i.e. nerve crush or cut. The findings suggest that, in the distal segment of crushed nerve, the lipid content as well as the myelin lipid synthesis increase as the regeneration period proceeds.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1983

Labeling of RNA in young and adult rat brain: evidence for different RNA processing.

The labeling of RNA in young and adult rat brain has been studied by measuring in vitro (tissue slices incubation) the incorporation of labeled uridine into RNA of total tissue and of the various subcellular fractions purified from cerebral hemispheres of 1- and 10-month-old rats. Gel electrophoretic analysis of the newly synthesized nuclear and microsomal RNA was also accomplished. An active metabolism of RNA in adult animals was found; moreover, distinct differences in ribosomal RNA processing in cerebral hemispheres of 1- and 10-month-old rats, with a more rapid processing in the brain of adult animals, were obtained.

Aging↗
PubMed1983

Rapid axonal transport of glycerophospholipids in regenerating hypoglossal nerve of the rabbit.

The intraaxonal transport of phospholipids in regenerating hypoglossal nerve of the rabbit was investigated by administration of labeled lipid precursors into the medulla oblongata. At various time intervals after crushing the left hypoglossal nerve at the level of the digastric muscle, a mixture of 60 mu Ci of [2-3H]glycerol and 15 mu Ci of [1-14C]palmitate, dissolved in 15% bovine serum albumin, was injected into the calamus scriptorius of the fourth ventricle. The amount and the pattern of labeling of glycerophospholipids synthesized in the motor neurons were determined. Three days after nerve crush there was an accumulation of labeled glycerophospholipids immediately proximal to the injury site. Seven days after crushing, the regenerating nerve incorporated rapidly transported labeled lipids in greater amounts than the contralateral normal nerve; the incorporation was elevated along the entire length of the nerve containing both regenerating axons and the post-crush sprouting terminals. The difference between the two sides increased up to 14 days, but disappeared as regeneration proceeded (21-45 days). The "pool" of radioactive lipids remaining in the cell bodies of hypoglossal nuclei, in the segments of nerve, both proximal and distal to the crush site, and in all the segments of uncrushed nerve was similar 6-12 h after labeling. Among the phospholipids, the highest 3H and 14C radioactivity was observed in phosphatidylcholine and phosphatidylethanolamine. These results support the hypothesis than an increase in the amount of glycerophospholipids, conveyed by rapid axonal transport, takes place in the first 2 weeks during nerve regeneration. The increased transport of lipids presumably reflects an augmented demand for membrane precursors during the sprouting process.

Animals↗
PubMed1983

Changes in rapid transport of phospholipids in the rat sciatic nerve during axonal regeneration.

Axonal transport of phospholipids in normal and regenerating sciatic nerve of the rat was studied. At various intervals after axotomy of the right sciatic nerve in the midthigh region and subsequent perineurial sutures of the transected fascicles, a mixture of 60 mu Ci [Me-14C]choline and 15 muCi [2-3H]glycerol in the region of the spinal motor neurons of the L5 and L6 segments was injected bilaterally. The amount of radioactive lipid (and in certain cases its distribution in various lipid classes) along the nerve was determined as a function of time. Three days after fascicular suture and 6 h after spinal cord injection of precursors, there was an accumulation of labeled phospholipids and sphingolipids in the transected sciatic nerve in the region immediately proximal to the site of suture. Nine days after, there was a marked increase in the accumulation of radioactivity in the distal segments of the injured nerve, which increased up to 14 days after cutting and disappeared as regeneration proceeded (21-45 days). In all segments of both normal and regenerating nerve fibers, as well as in L5 and L6 spinal cord segments, only phosphatidylcholine and sphingomyelin were labeled with [14C]choline. These results suggest that the regeneration process in a distal segment of a peripheral neuron, following cutting and fascicular repairing by surgical sutures, is sustained in the first 3 weeks by changes in the amount of phospholipids rapidly transported along the axon towards the site of nerve fiber outgrowth.

Animals↗
PubMed1983

[Prevention of ischemic heart disease: a feasibility study of health education in the primary school].

To verify the level of participation of children and teachers in an educational program, the reliability of the program itself and to determine whether children can modify family's behavioral patterns, a feasibility study was undertaken among the pupils of a primary school. Seventy-two children, belonging to different socio-economic classes, were studied. Children were given a questionnaire before and after the course, which was held by previously trained teachers. Very good participation of children and teachers in the program was observed. On the contrary very low involvement of the parents was achieved. This experience emphasizes the difficulties arising when actions to modify adult's life styles are attempted. On the contrary, a standardized education program, lasting for a whole school year, could be a feasible, useful and not too costly program not only for the primary prevention of coronary artery disease, but for any program of extensive health care.

Adolescent↗
PubMed1982

Changes in enzyme activities of glycerolipid metabolism of guinea-pig cerebral hemispheres during experimental hypoxia.

Hypoxic treatment causes changes of some enzymatic activities involved in the glycerolipid metabolism in subcellular fractions of guinea pig cerebral hemispheres. The activity of lysophosphatidylcholine acyltransferase, choline phosphotransferase, glycerol-3-phosphate acyltransferase(s), as well as the activity of triacylglycerol lipase significantly decreased in the microsomes of cerebral hemispheres of animals intermittently exposed to hypoxic treatment for eighty hours. At the same time, a marked activation of microsomal and mitochondrial phospholipase A2 occurred. The changes of the above-mentioned enzymatic activities after the hypoxic treatment correlated well with the increase in the level of brain and blood free fatty acids. The changes also correlated with the decrease of labeled lipid precursors incorporated into lipids of the cerebral hemispheres, observed during oxygen insufficiency.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1982

Transfer of axonally transported phospholipids into myelin isolated from the rabbit optic pathway.

The contribution of the axonal transport to the biosynthesis of myelin phospholipids was investigated in the rabbit optic pathway. A double labeling technique was used. The same animals were injected with one isotope intravitreally and the other intraventricularly. This procedure allows double labeling of the optic nerves, optic tracts, lateral geniculate bodies (LGB), and superior colliculus (SC). The precursors simultaneously injected were: [1-14C]palmitate (15 microCi intravitreally in both eyes or 50 microCi intraventricularly) and [2-3H]glycerol (50 microCi intravitreally in both eyes of 100 microCi intraventricularly). Twenty four hours and 10 days after the injections, myelin was purified from pooled optic nerves and optic tracts as well as from pooled LGBs or SCs. The phospholipids were extracted and then separated by thin-layer chromatography; the specific radioactivity of the various classes of phospholipids was determined. Using both administration routes of C- or 3H-precursors, the distribution of label and specific radioactivity of myelin phospholipids in the retina and in all other optic structures were very similar. Phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine + phosphoinositol were preferentially labeled with both precursors. These results suggest that, in the rabbit optic pathway the phospholipids synthesized in the retinal ganglion cells and transported along the axons, could undergo transaxonal transfer into myelin.

Animals↗
PubMed1981

Effect of CDP-choline on the biosynthesis of phospholipids in brain regions during hypoxic treatment.

Acute administration of CDP-choline (i.p. 100 mg/Kg b.w.), 10 min before the intraventricular injection of labeled precursors, [2-3H] glycerol and [1-14C]-palmitate, was able to correct the impairment caused by hypoxic treatment of lipid metabolism in some brain regions, ie, cerebral hemispheres, cerebellum, and brainstem. After CDP-choline treatment, an increase of the specific radioactivity of total lipids and of phospholipids was observed in mitochondria purified from the three above-mentioned brain regions of the hypoxic animals, while no effect on the other subcellular fractions was found. CDP-Choline had a stimulating effect particularly on the incorporation of both precursors into mitochondrial PC, PE, and polyglycerophosphatides isolated form the three brain regions examined. The results obtained show that the action of CDP-choline in restoring lipid metabolism was more pronounced in brain mitochondria, which, among subcellular fractions, were the most affected by the hypoxic treatment.

Animals↗