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Biomedical subjects

M Ledig

Publications and source records attributed to M Ledig.

At least 55 records · Page 3Linked to original sources
PubMed1983

Comparative investigations of glutaminase development in cerebral cortex of chick embryo and in primary cultures of neurons and glial cells.

Glutaminase activity was determined in pure cultures of neurons, glial cells and in mixed cultures obtained from chick embryo brain. The development of this enzyme was observed periodically over time and compared to its evolution in corresponding cerebral hemispheres during embryonic and postnatal development. The specific activity of brain glutaminase increased between the twelfth and sixteenth day of embryogenesis. A similar increase was observed in cultures of neuroblasts during the corresponding period of time, although the activity in culture was about one-third lower than in vivo. In contrast to neurons, there was no significant increase of glutaminase activity in glial cells before the fifteenth day of culture. The enzyme level in glial cells between the thirteenth and fifteenth days of culture was approximately 25% of that in 7- and 8-day-old neurons. The different development of glutaminase activity in neurons and glial cells was demonstrated in both pure and mixed cultures. The results support the hypothesis that there is a glutamine shunt from glial cells to neurons.

Animals↗
PubMed1983

[The pulmonary toxicity of mercury vapors in the rat].

Rats have been exposed for periods of 120 to 240 minutes to an atmosphere containing 6 +/- 0.7 mg per cu.m mercury vapor. All rats developed an acute respiratory distress which lead to death within 2 to 210 hours (mean 53.5 h). Microscopical examination of the lungs showed an oedema rich in fibrin, an epithelial necrosis, hyaline membranes and in two cases an interstitial fibrosis. Mercury levels in the lungs ranged between 0.5 and 9.37 micrograms per gramme wet weight. The activity of pulmonary superoxide dismutase was decreased to 1.57 +/- 0.66 micrograms per mg of soluble proteins, compared with the level of 5.01 +/- 0.76 micrograms per mg in control rats. This study confirm the pulmonary toxicity of mercury vapors observed in human intoxication.

Animals↗
PubMed1982

Modifications in energy metabolism during the development of chick glial cells and neurons in culture.

Developmental changes in lactate dehydrogenase (LDH), enolase, hexokinase (HK), malate dehydrogenase (MDH), and glutamate dehydrogenase (GDH) activities were measured in cultures of pure neurons and glial cells prepared from brains of chick embryos (8 day-old for neurons, 14 day-old for glial cells) as a function of cellular development with time in culture. The modifications observed in culture were compared to those measured in brain extracts during the development of the nervous tissue in the chick embryo and during the post-hatching period. A significant increase of MDH, GDH, LDH, and enolase activities are observed in neurons between 3 and 6 days of culture, whereas simultaneously a decrease of HK values occurs. In the embryonic brain between 11 and 14 days of incubation, which would correspond for the neuronal cultures to day 3 through 6, modifications of MDH, GDH, HK, and enolase levels are similar to those observed in neurons in culture. Only the increase of LDH activity is less pronounced in vivo than in cultivated cells. The evolution of the tested enzymatic activities in the brain of the chick during the period between 7 days before and 10 days after hatching is quite similar to that observed in cultivated glial cells (prepared from 14 day-old embryos) between 6 and 18 days of culture. All tested activities increased in comparable proportions. The modifications of the enzymatic profile indicate that some maturation phenomena affecting energy metabolism of neuronal and glial elements in culture, are quite similar to those occuring in the total nervous tissue. A relationship between the development of the energy metabolism of the brain and differentiation processes affecting neuroblasts and the glial-forming cells is discussed.

Animals↗
PubMed1982

Effect of hydrocortisone and thyroxine on ATPase activities of neuronal and glial cell lines in culture.

The effect of hydrocortisone and thyroxine, on the activities of Ca2+- and Mg2+- ATPase was studied in cultured neuronal (clone M1) and glial (clones NN and C6) cell lines. For M1 and NN cells an increase in Ca2+- and Mg2+-ecto-ATPase activity was found when the cells were cultured during 4-6 days in presence of hydrocortisone or together with thyroxine. In the same conditions, a decrease in Ca2+- and Mg2+-ecto-ATPase activity was found for the C6 cells. In C6 cells the effect of hormones was more pronounced for the Mg2+- than for the Ca2+-ecto-ATPase activity. The observed decrease may be related to the tumoral origin of the C6 cells. The activity of (Na+, K+)-ATPase in all three cell lines increased in presence of hydrocortisone or together with thyroxine when the cells were cultured during 4-6 days, in presence of the hormones, whereas the total Mg2+- ATPase activity increased only after 6 days of treatment. Thyroxine alone has very few effect either on Ca2+- and Mg2+-ecto-ATPase, or on (Na+, K+)- and total Mg2+-ATPase activity. These observations are interpreted to indicate that hormones may modulate or induce enzymatic activities involved in active transport phenomena in nervous tissue.

Adenosine Triphosphatases↗
PubMed1982

Regional distribution of superoxide dismutase in rat brain during postnatal development.

Superoxide dismutase in nervous system protects readily oxidizable compounds such as catecholamines against toxic effects of oxygen. We investigated superoxide dismutase activity during development in 5 brain regions selected for a wide range of catecholamine concentration and turnover: cerebellum, neocortex, striatum, hypothalamus and medulla-pons. The cytosolic and the particulate enzyme were measured from birth to 6 months of age. In cerebellum the cytosolic enzyme shows considerable activity on the first postnatal days; the particulate enzyme is less active, both reach a maximum at 3 months. In cortex and striatum both activities were low during the postnatal days and reach a plateau at 3 months. In hypothalamus both activities are higher during the postnatal days and reach a maximum at 3 months. In medulla-pons the values are 2 times higher than in all other regions; the cytosolic enzyme reaches a maximum at 2 months whereas the particulate enzyme reaches a plateau at 3 months. Thus our results show an increase of superoxide dismutase activity during development in all brain regions; the highest activities were found in regions with high catecholamine content.

Aging↗
PubMed1982

Neuron-specific and non-neuronal enolase in developing chick brain and primary cultures of chick neurons.

Developmental changes of the neuron-specific enolase (NSE) and the non-neuronal enolase (NNE) were determined in pure neuronal, or mixed cultures of neuronal and glial cells, prepared from brains of 8-day-old chick embryos, as a function of cellular development with time in culture. The modifications observed in culture were compared to those measured in brain during the development of the nervous tissue in the embryo and during the post-hatching period. In the whole brain, the total enolase activity increases progressively until the adult level, the NSE appears only 4 days before hatching. The total enolase activity of pure neurons increases until 8 days of culture but the NSE never appears during this period. Mixed cultures of neurons and glial cells present an increase of total activity until 14 days of culture and neuron-specific form of the enzyme can be observed after 6 days of culture. Our results suggest that NSE appears only in the functional brain and is expressed in cultivated neurons only when glial cells are present simultaneously.

Animals↗
PubMed1982

Free amino acids in the brain of ethanol treated rats.

Both acute and chronic ethanol administration to rats produce changes in free amino acids involved in nervous system function. Glutamic and aspartic acid levels are especially increased. Chronic ethanol treatment produces in addition an increase in GABA and a decrease in glutamine level. Taurine and glycine were not affected by ethanol. These variations may be explained by changes in transport phenomena and in the redox balance. They seem to correlate with the behavioural effects of acute and chronic alcohol intoxication. Tyrosine, phenylalanine and tryptophan which are related to serotonin and catecholamines formation, were found to be decreased by acute and short chronic ethanol administration.

Amino Acids↗
PubMed1981

Superoxide dismutase activity in rat brain during acute and chronic alcohol intoxication.

The effect of acute and chronic ethanol administration on rat brain superoxide dismutase (SOD) activity was studied. Intraperitoneal injections of ethanol led to an inhibition of SOD activity. When ethanol was fed as the sole fluid, the SOD activity decreased progressively, reaching a plateau after 6 weeks of treatment. Withdrawal of ethanol produced a recovery of control values within 48 hr. SOD activity was also decreased in rats born from ethanol-drinking mothers. Inhibition of SOD activity by ethanol may allow an accumulation of cytotoxic O2 - radicals; this may account for some nervous system disorders during alcohol intoxication.

Alcoholic Intoxication↗
PubMed1980

Biochemical correlates of tolerance in rodents and in Drosophila. Possible role of alcohol dehydrogenase, aldehyde dehydrogenase and superoxide dismutase.

In the rat, prolonged exposure to ethanol (ETOH) vapor induced an acquired increase in tolerance. After a single ETOH administration, the duration of recovery was decreased by 20% as compared to control animals and the rate of ETOH elimination from blood was increased by 27%. From the data obtained on liver enzymes--alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH) and superoxide dismutase (SOD)--it is suggested that the increased ALDH activity would be the consequence of an increased formation of the product of ETOH oxidation, the acetaldehyde. This over-production would not be accounted for by ADH. It is assumed that among others, the coupled reaction SOD-catalase would represent a possible alternate pathway. Data on Drosophila demonstrate that initial tolerance to ETOH is well correlated with ADH activity. It is suggested that ETOH metabolites (mainly acetaldehyde) would act also as determinant of this initial tolerance. The value of Drosophila as animal model for the study of behavioral and biochemical correlates of initial tolerance is discussed.

Alcohol Oxidoreductases↗
PubMed1980

Effect of ethanol on superoxide dismutase activity in cultured neural cells.

Superoxide dismutase (EC 1.15.1.1) activity was investigated in several types of neural cells cultivated in the presence of 100 mM ethanol. Superoxide dismutase was inhibited by acute treatment with ethanol. Chronic treatment with ethanol specifically inhibited superoxide dismutase in glial cells. In all instances withdrawal of ethanol produced a quick return to control values. Inhibition of superoxide dismutase by ethanol may increase toxic oxygen radicals in nervous tissue.

Animals↗
PubMed1980

Study of some enzyme activities in cultured chick embryo brain nerve cells treated by chick embryo brain extracts.

Brain extracts from 8-day-old chick embryos have been shown to influence morphological development of dissociated brain cells from 7-day-old chick embryos in culture. Stimulatory effects on size of the neuronal somas and on growth of long processes were observed by adding the cytosol of the brain extract or the dialysate of the cytosol. These morphological changes parallel modifications of various enzyme activities according to the age of the cultures. Adenyl cyclase, (Na+,K+)- and Mg2+-ATPase, 5'-nucleotidase, choline acetyltransferase, and acetylcholinesterase activities were studied between 5 and 14 days of culture. Adenyl cyclase activity was strongly stimulated at 8 days by both extracts. (Na+,K+)- and Mg2+-ATPase activities were stimulated in 8-day-old cultures only by the dialysate. 5'-Nucleotidase activity was stimulated in 8-day-old cultures by the dialysate and in 11-day-old cultures by both extracts. Choline acetyltransferase activity was stimulated by the cytosol in 8-day-old cultures and by the dialysate in 11-day-old cultures. The total acetylcholinesterase activity was higher in 8-, 11-, and 14-day-old cultures treated with the cytosol. When the cells were treated with the dialysate, the activity was only higher in 14-day-old cultures. We also found that following the addition of brain extracts, the specific activity of the enzymes we studied was enhanced and became close to the values found in vivo during embryogenesis. Thus in parallel to the morphological modifications observed in nerve cell cultures treated by embryo brain extracts, biochemical variations especially involved in synaptogenesis and membrane development could be measured.

Acetylcholinesterase↗
PubMed1980

Ethanol and neuronal metabolism.

The effect of ethanol on membrane enzymes (Na+, K+ and Mg2+ ATPases, 5'-nucleotidase, adenylate cyclase) alcohol dehydrogenase, aldehyde dehydrogenase and superoxide dismutase were studied in nerve cells (established cell lines, primary cultures of chick and rat brain) cultured in the presence of 100 mM ethanol, and in total rat brain, following various ethanol treatments of the rats (20% ethanol as the sole liquid source, intraperitoneal injection). The results show a difference between neuronal and glial cells. Most of the observed changes in enzymatic activities returned rapidly to control values when ethanol was withdrawn from the culture medium or from the diet. Alcohol dehydrogenase was more stimulated by ethanol than aldehyde dehydrogenase; therefore acetaldehyde may be accumulated. The inhibition of superoxide dismutase activity may allow an accumulation of cytotoxic O2- radicals in nervous tissue and may explain the polymorphism of lesions brought about by alcohol intoxication.

Adenosine Triphosphatases↗
PubMed1978

Purification of a soluble ATPase from rat liver mitochondria by AMP-Sepharose affinity chromatography.

ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity was shown in the soluble fraction of rat liver micochondria. Two molecular forms (ATPase 1 and 2) were isolated. ATPase 1 has already been studied. The present paper deals with the purification method of ATPase 2 which was achieved by the following steps: (NH4)2SO4 precipitation. DEAE-cellulose chromatography, hydroxyapatite chromatography, Sephadex G100 filtration and AMP-Sepharose affinity chromatography. The purified protein was characterized by bidimensional polyacrylamide gel electrophoresis. Molecular weight evaluated by SDS-polyacrylamide gel electrophoresis and Sephadex G100 gel filtration was found to be 61 500 +/- 3000.

Adenosine Monophosphate↗
PubMed1978

Superoxide dismutase activity in nerve cell culture.

Superoxide dismutase (EC 1.15.1.1) activity was assayed in preparations obtained from several clonal lines of nerve cell culture, by enzymatic and nonenzymatic assays. The enzyme was found in dialyzed homogenates of washed cells and in partially purified fractions. The enzyme was also found in cells which had been grown in media containing 5-bromodeoxyuridine, where cell differentiation was observed.

Astrocytoma↗
PubMed1978

[Extraction and purification of tissue phosphopeptides].

We describe a method of extraction and partial purification of phosphopeptides isolated from pig brain or from the electrical organ of Torpedo marmorata. The extraction of the phosphopeptides was achieved by alcoholic 0,04 N potassium hydroxyde solution or by 10(-1) M KCL containing 10(-3) M EDTA and 10(-4) M DTT. After having tried various fractionation methods like ion exchange chromatography or gel filtration we chose chromatography on DEAE Sephadex followed by purification of the isolated fractions by Sephadex G 25 filtration. The most important phosphate fractions (one was purified to about 90 per cent) were characterized by the determination of the N/P ratio which was different from one phosphopeptide to another. The amino acid composition showed a high glycin, serine and "acid" amino acid content. The presence of phosphoserine was shown by electrophoresis and chromatography of a partial hydrolysate of in vivo 32P labelled phosphopeptides isolated from rat liver. The polyanionic structure of these phosphopeptides allow them to act as real ion exchangers which might be involved during active transport mechanisms in cellular membranes.

Amino Acids↗
PubMed1978

Studies of soluble rat liver mitochondrial acid ATPases. II. Structural and immunological properties of ATPase 1.

We described previously the existence of a soluble ATPase activity in rat liver mitochondria [1]. The purification and catalytic properties have been described [2]. In a continuation of these experiments, we have studied the immunologic and structural properties of one molecular form of this enzyme : ATPase I. We have prepared the antiserum anti-ATPase I and demonstrated the purity of our enzyme preparation by immunodiffusion and immunoelectrophoresis. An immunohistochemical method also confirmed the localization of ATPase I in the soluble fraction of mitochondria. The molecular weight of ATPase I was measured by G 100 Sephadex gel filtration and was found to be 18,400; electrophoresis on polyacrylamide gels gave a value of 18,600. The pHi of ATPase I was found to be 7,2. Amino acid analysis showed high amounts of aspartic acid, glutamic acid, serine and glycine. The molecular weight calculated from the total amino acid residues was found to be 17,000. Alanine is the NH2 terminal amino acid. The peptide maps obtained after degrading ATPase I with cyanogen bromide or trypsin are in accordance with the methionine, lysine and arginine residues we found in the ATPase I molecule. ATPase I does not appear to be a glycoprotein.

Adenosine Triphosphatases↗