Search PubMed⌕ Search

Biomedical subjects

M Renis

Publications and source records attributed to M Renis.

At least 37 records · Page 2Linked to original sources
PubMed1994

Lipid peroxidation and survival in rats following cerebral post-ischaemic reperfusion: effect of drugs with different molecular mechanisms.

In the present study the authors investigated the effect of pretreatment with exogenous antioxidants such as deferoxamine (iron chelating drug), allopurinol (competitive inhibitor of xanthine oxidase) and vitamin E (scavenger of oxygen free radicals) on lipid peroxidation in rat cerebral cortex after post-ischaemic reperfusion, and on the survival rate. The effect of pretreatment with two calcium-antagonist drugs (diltiazem and verapamil) was also evaluated under the same experimental conditions. Pretreatment with exogenous antioxidants and with calcium-antagonist drugs significantly decreased cerebral conjugated diene levels (index of lipoperoxidation) with a concomitant increase in survival with respect to untreated ischaemic rats.

Allopurinol↗
PubMed1994

Heat shock proteins following rat cerebral ischemic/reperfusion episode: effect of ketamine.

This paper reports the influence of ketamine on HSP70 expression, during an ischemic/reperfusion episode, in rat cerebral cortex and hippocampus. The results indicate that ketamine, injected 1h before the surgical treatment, increases HSP70 cellular concentration in both ischemic and sham-operated animals. The HSP70 levels, after the transient ischemic episode, are higher in ketamine treated than in urethane-treated animals respect to the control levels. After reperfusion an increase of HSP70 levels is observed; this induction is maintained for at least 22h, irrespective of the anaesthetic drug treatment. Comparing the cerebral areas examined, the hippocampus exhibits higher protein levels than those of the cerebral cortex.

Animals↗
PubMed1993

Free radical scavenger depletion in post-ischemic reperfusion brain damage.

In the present study the influence of pretreatment with various GSH depletors such as buthionine sulfoximine (BSO) and diethylmaleate (DEM) was investigated in rats following cerebral post-ischemic reperfusion. Moreover, the effect of diethyldithiocarbamic acid (DDC), inhibitor of endogenous Cu,Zn-SOD, was evaluated. A significant depletion (40% of control value) of GSH levels was observed 24 h after DEM administration; after 48 h the value reached control levels. BSO showed maximal GSH depletion (59%) 24 h after administration and it was constant for almost 48 h. DDC administration caused a marked decrease (60%) of Cu,Zn-SOD activity 4 h after the injection and induced a marked decrease in percentage of survival with respect to control (untreated, ischemic) rats, when administered 4 h before ischemia. BSO and DEM prolonged the survival time of animals when administered 24 h before ischemia. This last paradoxical effect is unclear at present, but it might be due to an influence on glutamate cascade.

Animals↗
PubMed1992

Transglutaminase activity in primary and subcultured rat astroglial cells.

Transglutaminases, calcium-dependent thiol enzymes, may be involved in cellular growth control and differentiation, having an intracellular regulatory role in some post-translational modifications found in various classes of proteins. In order to elucidate the involvement of this class of enzymes in cellular differentiation processes, we have assayed transglutaminase activity in primary and subcultured rat glial cells. Reduced activity was found from 3rd to 5th passage. In the 5th passage the activity was some 50% of that found in the primary cultures and was not restored by addition of 10 microM retinoic acid. The decrease of TGase activity, observed during serial passages, could represent an early metabolic alteration related to cell dedifferentiation and loss of growth control. In fact, the subcultured cells may have undergone a "disarranged" state, as confirmed by a decrease in GFAP-stained cells and glutamine synthetase activity, respectively, immunocytochemical and biochemical markers of astroglial cells.

Animals↗
PubMed1990

Reduced transcription of mitochondrial DNA in the senescent rat. Tissue dependence and effect of L-carnitine.

A quantitative study on the effect of senescence on mitochondrial DNA expression has been carried out by measuring the levels of the 12S rRNA and of the mRNA for the subunit I of cytochrome oxidase in several tissues of adult and senescent rats. The concentration of both RNA species/mitochondrial DNA molecule is significantly reduced in senescent brain and heart, as opposed to the respective adult tissues. No appreciable variation occurs in the liver. A 1-h pretreatment with acetyl-L-carnitine brings back the level of senescent brain and heart transcripts to that of adult tissues. The same treatment of adult rats does not cause significant changes in mitochondrial RNA content. These results suggest that the age-dependent impairment of both heavy-strand mitochondrial DNA transcription units is related to altered environmental conditions which acetyl-L-carnitine, a substance which acts by stimulating, directly or indirectly, the energy metabolism, is able to remove.

Acetylcarnitine↗
PubMed1989

Age-dependent changes of nucleic acid labeling in different rat brain regions.

The effects of aging on in vivo DNA and RNA labeling and on RNA content in various brain regions of 4-, 12-, and 24-month-old rats were investigated. No difference in [methyl-14C]thymidine incorporation into DNA of cerebral cortex and cerebellum during aging was observed. The ratio of RNA/DNA content significantly decreased from 4 to 24 months of age in cerebral cortex, cerebellum and striatum. RNA labeling decreased by 15% in cerebral cortex of 24-month-old animals while in the other brain areas examined (cerebellum, hippocampus, hypothalamus, brainstem, striatum) did not change during aging. In the cerebral cortex, the ratio of the specific radioactivity of microsomal RNA to that of nuclear RNA, determined by in vivo experiments, was not affected by the aging process. A significant decrease of total, poly(A) RNA and poly(A) RNA content was observed in the same brain area of 24-month-old rats compared to 4-month-old ones. Moreover, densitometric and radioactivity patterns obtained by gel electrophoresis of labeled RNA after in vitro experiments (tissue slices of cerebral cortex) showed a different ribosomal RNA processing during aging. In vivo chronic treatment with CDP-choline was able to increase RNA labeling in corpus striatum of 24-month-old animals.

Aging↗
PubMed1989

Content of mitochondrial DNA and of three mitochondrial RNAs in developing and adult rat cerebellum.

The content of DNA and of 16S rRNA and of two mRNAs, i.e., the mRNA for the cytochrome c oxidase subunit I and the mRNA for one subunit of the NADH dehydrogenase (ND4), in free (nonsynaptic) mitochondria of developing and adult rat cerebellum has been determined. During postnatal development, DNA content of free (nonsynaptic) mitochondria increases 10 times from 1 to 30 days of age whereas, in adult rats, it is about 60% compared to that found in 30-day-old rats. The total content of each RNA species studied also increases during development. However, when the content of each RNA is expressed per mtDNA molecule, rRNAs and mRNAs behave differently: 16S rRNA level does not change during development and it is not significantly different from that of the adult rat, whereas the level of mRNAs is higher during development than in the adult rat and changes with age. These results are discussed in light of mitochondrial biogenesis in rat cerebellum during development and of the regulation of the mitochondrial DNA transcription process.

Animals↗
PubMed1988

Protein synthesis rates in rat brain regions and subcellular fractions during aging.

In vivo protein synthesis rates in various brain regions (cerebral cortex, cerebellum, hippocampus, hypothalamus, and striatum) of 4-, 12-, and 24-month-old rats were examined after injection of a flooding dose of labeled valine. The incorporation of labeled valine into proteins of mitochondrial, microsomal, and cytosolic fractions from cerebral cortex and cerebellum was also measured. At all ages examined, the incorporation rate was 0.5% per hour in cerebral cortex, cerebellum, hippocampus, and hypothalamus and 0.4% per hour in striatum. Of the subcellular fractions examined, the microsomal proteins were synthesized at the highest rate, followed by cytosolic and mitochondrial proteins. The results obtained indicate that the average synthesis rate of proteins in the various brain regions and subcellular fractions examined is fairly constant and is not significantly altered in the 4 to 24-month period of life of rats.

Aging↗
PubMed1986

Nuclear and mitochondrial DNA synthesis and energy metabolism in primary rat glial cell cultures.

DNA synthesis in nuclei and mitochondria purified from serum-supplemented rat glial cell cultures at different days after plating was studied. Furthermore in mitochondria, some enzymatic activities related to energy transduction (citrate synthase, malate dehydrogenase, total NADH-cytochrome c reductase, cytochrome oxidase and glutamate dehydrogenase) were measured. For DNA labeling [methyl-3H]thymidine was added to the culture medium at different days after plating. During the culture times studied the specific activity of total, nuclear, and mitochondrial DNA decreased from 8 days in vitro (DIV) to 21 DIV and increased at 30 DIV. The specific activity of nuclear DNA was always higher than that of mitochondrial DNA. The specific activity of the above mentioned mitochondrial enzymes increased from 8 DIV up to 21 DIV and decreased at 30 DIV, suggesting a relationship between the energy metabolism and the differentiation of glial cells in culture.

Animals↗
PubMed1986

Mitochondrial DNA, RNA and protein synthesis in normal and hypothyroid developing rat liver.

Mitochondrial DNA, RNA and protein synthesis in normal and hypothyroid rat liver between the ages of -3 and 21 days were followed. In normal rats DNA polymerase activity and protein synthesis behaved similarly, showing two peaks of activity, one at -3 and the other at 21 days of age. RNA polymerase activity did not change between days -3 and 14, whereas it increased by 21 days of age. Hypothyroidism delayed the developmental pattern of DNA polymerase activity, affected RNA polymerase activity only at 21 days, whereas it inhibited protein synthesis at birth and in the third week of life. The cytochrome aa3 content appeared to be affected by hypothyroidism at birth and at 21 days of age.

Animals↗
PubMed1986

Acetylation and phosphorylation of histones and nonhistone chromosomal proteins in neuronal and glial nuclei purified from cerebral hemispheres of developing rat brain.

The processes of acetylation and phosphorylation of histones and nonhistone proteins (NHPs) in neuronal and glial nuclei purified from cerebral hemispheres of rats at 1, 10, and 30 days of age were investigated. Purified neuronal and glial nuclei were incubated in the presence of [3H]acetyl-CoA and of [gamma-32P]ATP. Histones and NHPs were extracted and fractionated by gel electrophoresis. Densitometric and radioactive patterns were obtained. The results showed an increase of acetylation and phosphorylation from 1 to 10 and 30 days of age in both neuronal and glial nuclei in almost all histone and NHP fractions. Among the histones, the H3 fraction was always more labeled than the other fractions and showed the most remarkable differences during postnatal development. In the NHP fractions, the increase in acetylation from 1 to 10 and 30 days of age was more evident in the low-molecular-weight region of neuronal nuclei than in the corresponding fraction of glial nuclei. The appearance of highly phosphorylated proteins (70,000-90,000 daltons)--absent at 1 day, appearing at 10 days, and more evident at 30 days of age--was observed in both neuronal and glial nuclei.

Acetylation↗
PubMed1986

Human polymorphic APO-LDL investigated by high-resolution two-dimensional electrophoresis.

The APO part of a human polymorphic low density lipoprotein (LDL) was investigated by two-dimensional electrophoresis. Since these allotypic LDL were purified from sera by specific immunochromatography, the data presented here refer to only one molecular species of LDL. The two-dimensional electrophoresis revealed the presence of isoforms which were correlated to the serological phenotype. A hypothesis about APO-LDL gene organization is outlined.

Apolipoproteins↗
PubMed1985

Effect of hypothyroidism on the biogenesis of free mitochondria in the cerebral hemispheres and in cerebellum of rat during postnatal development.

The effect of propylthiouracil-induced neonatal hypothyroidism on some aspects of the biogenesis of free (non-synaptosomal) mitochondria in the cerebral hemispheres and in the cerebellum of developing rat has been studied. The results obtained show that in hypothyroid rats mitochondrial DNA synthesis is delayed, mitochondrial RNA synthesis is not affected and cytochrome aa3 content of mitochondria is lower than in controls. Furthermore ultrathin sections of 14- and 21-day old hypothyroid rat cerebella show mitochondria with an altered ultrastructural organization and large intracristal spaces.

Animals↗
PubMed1985

Effect of hypothyroidism on the labeling of the various RNA species in developing rat brain.

The effect of hypothyroidism on the vitro incorporation of [3H]uridine into different RNA species in tissue slices of rat cerebral hemispheres at 5, 10, 15, and 21 days of age has been investigated. Gel electrophoresis analysis of total, nuclear and microsomal RNA was also accomplished. The results obtained indicate that RNA labeling is differently influenced by hypothyroidism at the various ages examined. RNA labeling is not significantly affected at 5 days of age while at later ages and especially at 21 days it is higher in hypothyroid rats compared to the controls. Moreover distinct differences at the various ages in the transport of newly synthesized RNA from the nucleus to the cytoplasm in the two groups of animals were found. These results are in agreement with the hypothesis that thyroid hormone deficiency causes a delay of the processes of cell proliferation and differentiation in developing rat brain.

Age Factors↗
PubMed1979

Macromolecular synthesis in mitochondria isolated from different regions of developing rat brain.

DNA, RNA, and protein synthesis in mitochondria isolated from cerebral hemispheres, brain stem, and cerebellum of 10- and 30-day-old rats was measured. Synthesis of different macromolecules was affected by the respective mitochondrial specific inhibitors, showing a good level of purity of mitochondrial preparations. DNA and protein synthesis in 10-day-old rats was about 70% higher than in 30-day-old animals. In contrast, RNA synthesis did not decrease with age in all the regions examined.

Aging↗
PubMed1979

Mitochondrial DNA, RNA, and protein synthesis in different regions of developing rat brain.

In vivo and in vitro (tissue slices) incorporation of labeled precursors into DNA, RNA, and proteins was measured in mitochondria obtained from cerebral hemispheres, cerebellum, and brain stem of rats at different days of postnatal development. To compare the synthesis of macromolecules in mitochondria with that in other subcellular fractions, the incorporation of labeled precursors into DNA, RNA, and proteins extracted from nuclei and into RNA and proteins extracted from microsomes and cytoplasmic soluble fractions was also measured. The results obtained showed that the incorporation of [3H]thymidine into DNA and of [14C]leucine into proteins of nuclei and mitochondria from the various brain regions examined decreased during postnatal development; however, at 30 days of age the specific radioactivity of mitochondrial DNA was higher than that of nuclear DNA. [3H]Uridine incorporation into RNA decreased from 10 to 30 days of age in nuclei while in mitochondria it was quite similar at both ages. This result may be due to a faster turnover of mitochondrial RNA compared to that of mitochondrial DNA and proteins. The results obtained suggest an active biosynthesis of macromolecules in brain mitochondria and might indicate an intense biogenesis of these organelles in rat brain during postnatal development.

Animals↗
PubMed1978

MAO activity in rat brain stem and cerebral cortex: effect of acute and chronic treatment with ethanol and tetrahydropapaveroline.

Brain mitochondria were prepared from rat brain stem and cerebral cortex. Four substrates were used for enzyme characterization: dopamine, serotonin, noradrenaline and tryptamine. Monoamine oxidase (MAO) activities were tested on two different groups of rats treated with ethanol and tetrahydropapaveroline (THP); another group was used as control group. Data obtained show that there is almost always activation of MAO activities after acute treatment with either ethanol or THP, while after chronic treatment, the two drugs show opposite effects. In particular, the same type of MAO activity continues to be activated by ethanol, whereas it is inhibited by THP.

Animals↗