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T Grune

Publications and source records attributed to T Grune.

At least 127 records · Page 7Linked to original sources
PubMed1992

Adaptational increase of liver glutathione content during long-term application of cyclosporine A may attenuate toxic side effects.

The concentrations of reduced and oxidized glutathione and of adenine nucleotides were determined in liver, kidney and heart of rats during long-term (four weeks), high-dose therapy with cyclosporine A. In liver and kidney the concentration of oxidized glutathione increased following 4 weeks-therapy suggesting increased formation of free radicals and accelerated lipid peroxidation processes. These processes may be due to an increased activity of the cytochrome P-450 system. Compensatory levels of reduced glutathione were also increased. The adaptational increase of the tissue level of reduced glutathione, presumably the response to a chronic oxidative stress, was more distinct in the liver. The liver did not lose adenine nucleotides. In contrast the kidney, after 4 weeks of cyclosporine A therapy, lost 25% of the adenine nucleotides. These findings suggest that the liver is characterized by a greater potential for effective adaptation to oxidative stress conditions compared to the kidney. These adaptations may prevent distortions of energy and nucleotide metabolism in the liver which is in agreement with the minor ultrastructural changes we have observed.

Adaptation, Physiological↗
PubMed1992

Adenine metabolism of Ehrlich mouse ascites cells in proliferating and resting phase of tumor growth.

The incorporation of 14C from [U-14C]adenine into the pools of purine nucleotides, nucleosides and bases in Ehrlich mouse ascites cells (EMAC1) during the proliferating and resting phases of tumor growth was compared. In the proliferating phase the total 14C incorporation into purine pools is much faster than in the resting phase. The ATP turnover as well as the purine breakdown to hypoxanthine and uric acid are increased in the proliferating phase. That corresponds to previous findings on higher nucleotide pool sizes and higher ATP yield and ATP-consuming processes in this growth period.

Adenine↗
PubMed1992

Protective influence of oxypurinol on the trinitrobenzene sulfonic acid(TNB) model of inflammatory bowel disease in rats.

Chronic inflammation of the colon and the rectum was induced by intracolonic administration of 25 mg trinitrobenzoic sulfonic acid (TNB) in 0.25 ml 30% ethanol. Three weeks after TNB administration the colon and the rectum showed transmural, granulomatous inflammation which had many similarities to Crohn's disease and furthermore to the morphological and functional changes which occur in early phases of postischemic intestinal damage. In the colon of TNB-treated animals the ATP and GTP levels were markedly decreased. The accumulation of thiobarbituric acid-reactive substances (TBA-RS) demonstrated a free radical-mediated component of the tissue damage. Treatment with oxypurinol radical scavenger and xanthine oxidoreductase inhibitor diminished the morphological changes, the loss of energy-rich nucleotides and the TBA-RS accumulation.

Animals↗
PubMed1991

Determination of the ultraviolet absorbance and radioactivity of purine compounds separated by high-performance liquid chromatography. Application to metabolic flux rate analysis.

A double detection system for the determination of adenine metabolism in biological tissues using isocratic ion-pair reversed-phase chromatography is presented. Two isocratic ion-pair separations were used: (i) 10 mM NH4H2PO4, 2 mM tetrabutylammonium phosphate (PIC reagent A) and 18% acetonitrile for the determination of nucleotides and (ii) 50 mM KH2PO4, 1 mM PIC reagent A and 1% acetonitrile for the determination of monophosphorylated nucleotides, nucleosides and nucleobases. The parallel detection of ultraviolet absorbance at 254 nm and the radioactivity of separated purine compounds allows the detection of pool sizes and of the specific radioactivities in tracer kinetic experiments. The high-performance liquid chromatography methods were applied to the determination of flux rates during adenine nucleotide metabolism in suspensions of Ehrlich mouse ascites tumour cells. The pathways of adenine metabolism in cells during the proliferation and plateau phases of tumour growth were compared.

Animals↗
PubMed1991

Changes of nucleotide patterns in liver, muscle and blood during the growth of Ehrlich ascites cells: application of the reversed-phase and ion-pair reversed-phase high-performance liquid chromatography with radial compression column.

The pool of purine compounds was analysed in liver, skeletal muscle and blood of mice during the growth of Ehrlich ascites tumour cells. Three fast isocratic high-performance liquid chromatographic methods were used. (1) Determination of nucleotides by an isocratic ion-pair reversed-phase chromatography with a 10 mM ammonium phosphate buffer containing acetonitrile and tetrabutylammonium phosphate. (2) Separation of nucleosides and nucleobases in cell extracts by a reversed-phase system with methanol and 50 mM potassium phosphate buffer as eluent. (3) Nucleosides and nucleobases in body fluids were analysed by a reversed-phase system with 10 mM potassium phosphate containing methanol. These methods allow the rapid determination of purine compounds in small biological samples from various cell types and body fluids, with high accuracy and sensitivity. The pool of cellular nucleotides increased during the exponential phase of tumour growth. Adenosine accumulated significantly in all tissues in the stationary phase of tumour growth.

Animals↗
PubMed1991

Superoxide dismutase promotes ATP and GTP restoration of rat small intestine during postischaemic reperfusion.

The small intestine of rats was prepared according to a procedure which is taken for preservation and transplantation in clinical practice. The blood supply of the rat intestine was completely interrupted for 30 min in situ. During this period the lumen of the intestine was rinsed with Ringer-lactate solution. This ischaemic period was followed by 10 min of reperfusion. As a result a decrease in ATP, and GTP concentrations, and of the total adenine nucleotide content during the preservation period occurred. In animals pretreated with superoxide dismutase (i.v. application; superoxide dismutase preparation from human erythrocytes) an accelerated restoration of nucleotide concentrations during the reperfusion period was observed. From the beneficial effect of superoxide dismutase it can be concluded, that there is a considerable formation of active species of oxygen which disturb the energy generation by the mitochondrial respiratory chain during ischaemia/re-oxygenation.

Adenine Nucleotides↗
PubMed1991

Identification of metabolic pathways of the lipid peroxidation product 4-hydroxynonenal by enterocytes of rat small intestine.

The cytotoxic lipid peroxidation product 4-hydroxynonenal (HNE1) is rapidly metabolized in enterocytes. The degradation of HNE and other aldehydic products of lipid peroxidation processes seems to be an antioxidative defense system. The metabolism of HNE was studied in suspensions of rat enterocytes at 37 degrees C, pH 7.4 and at initial HNE concentration of 100 microM. About 70% of the HNE were degraded within three minutes of incubation. Main products of HNE which were identified in enterocytes were the glutathione-HNE-1:1-conjugate, the hydroxynonenoic acid and the 1,4-dihydroxynonene. Furthermore, the formation of metabolites of the tricarboxylic acid cycle is suggested. The quantitative share of HNE binding to proteins was low with about 1% of total HNE consumption after three minutes of incubation.

Aldehydes↗
PubMed1991

Discrepancy between biochemical normalization and morphological recovery of jejunal mucosa during postischemic reperfusion in presence of the xanthine oxidase inhibitor oxypurinol.

An increased formation of oxygen free radicals in the reperfused rat small intestine is concluded from accumulations of oxidized glutathione, of thiobarbituric acid-reactive substances and of 4-hydroxynonenal. Xanthine oxidase inhibition prevented these biochemical changes. The histological and electronmicroscopic studies of intestinal sucosa showed significant structural deteriorations already at the end of the ischemic period obviously due to disturbances of cellular energy metabolism. The extent of dosage was increased during the reperfusion without qualitative changes of the pattern of structural dosage. The beneficial effects of oxypurinol on biochemical criteria which occurred already in the early phase of reperfusion were not reflected in significant morphological differences within the first hour of reperfusion. Differences of morphological findings between oxypurinol-treated and untreated animals could be observed after longer periods of reperfusion--during the regeneration of the tissue.

Animals↗
PubMed1990

Aldehyde and nucleotide separations by high-performance liquid chromatography. Application to phenylhydrazine-induced damage of erythrocytes and reticulocytes.

High-performance liquid chromatographic (HPLC) techniques were used for the determination of aldehydes as lipid peroxidation products and of nucleotide concentrations in rabbit red blood cells exposed to phenylhydrazine hydrochloride. Aldehydes were determined by derivatization to dinitrophenylhydrazones, followed by thin-layer chromatographic and HPLC separation with methanol-water on an ODS column. Nucleotides and their derivatives were measured by ion-pair reversed-phase HPLC gradient elution with 10 mM ammonium phosphate buffer containing 2 mM tetrabutylammonium phosphate on ODS columns. The sensitivity of mature erythrocytes was compared with that of reticulocytes against the toxicological effects of phenylhydrazine. For both cell types an increase in aldehyde concentrations, especially of 4-hydroxynonenal, and a decline in both energy-rich nucleoside triphosphate and NAD+ were demonstrated.

Aldehydes↗
PubMed1990

Interrelation between nucleotide degradation and aldehyde formation in red blood cells. Influence of xanthine oxidase on metabolism: an application of nucleotide and aldehyde analyses by high-performance liquid chromatography.

The mechanism by which hypoxia leads to irreversible cellular damage is poorly understood. A decrease in purine nucleotides is common to all ischaemic tissues, yielding hypoxanthine as the substrate of the xanthine oxidase reaction. Excessive production of radicals via xanthine oxidase induces peroxidation of unsaturated fatty acids, accompanied with the formation of aldehydes. The nucleotides and aldehydes were determined by high-performance liquid chromatography (HPLC) of red blood cell extracts. Nucleotides and their derivatives were determined by HPLC on an ODS column and elution with 10 mM phosphate buffer containing 2 mM tert.-butylammonium phosphate. The aldehyde production in glucose deprived red blood cells was stimulated by addition of xanthine oxidase and by inhibition of different haemotype enzymes with sodium azide. Aldehydes were analysed by derivatization to dinitrophenylhydrazones, followed by thin-layer chromatographic and HPLC separation with aqueous methanol on an ODS column. The HPLC methods presented are appropriate for the determination of nucleotides, nucleosides and nucleobases, in addition to alkenals and hydroxyalkenals in extracts of oxidatively stressed red blood cells.

Aldehydes↗
PubMed1990

Balancing of energy-consuming processes of rat hepatocytes.

A method for the quantification of energy consuming processes described by Siems et al. for reticulocytes and by Müller et al. for ascites tumour cells was applied to balance the ATP-consumption of isolated rat hepatocytes. On the basis of decreased coupled respiration rates following the specific inhibition of energy-requiring reactions, the energy demands of protein turnover, nucleic acid synthesis, Na+/K(+)-ATPase and Ca2(+)-transport of hepatocytes in different incubation media were assessed. These processes together with urea synthesis account for about 60 per cent of the total energy consumption in a glucose and amino acid-enriched Eagle/Borsook medium. The metabolic flux rates of total ATP-consumption and ATP-consumption of single energy-requiring processes in hepatocytes are compared with those in reticulocytes and different tumour cell types.

Adenosine Triphosphate↗
PubMed1990

Long term effects of monthly low dose whole body irradiation on the glutathione status and thiobarbituric acid-reactive substances in different organs of male Wistar rats.

Male Wistar-H-rats were exposed monthly to a 60cobalt-source low dose whole body irradiation (0.25 Gy, total dose: 4.5 Gy). The glutathione disulphide:total glutathione ratio, the concentration of thiobarbituric acid-reactive substances and the activities of glutathione peroxidase and glutathione transferase in eight different organs and blood were analysed. The low dose irradiation is accompanied by distinct peroxidative changes in organs. These oxidative loadings occur in the small intestine, the spleen and the kidneys. The measurements of glutathione status and of thiobarbituric acid-reactive substances are proposed as sensitive parameters for low dose radiation induced changes.

Animals↗
PubMed1990

[Metabolic pool of purine compounds in erythrocytes of mice during growth of transplanted tumors].

The pattern of purine derivatives was studied in the erythrocytes of C3HA and ICR mice during Hepatoma 22 and Ehrlich ascites tumor cells growth. Host erythrocytes purine nucleotides, nucleosides and bases were affected by the implanted tumors. The results indicated that the host erythrocytes markedly concentrated adenine and guanine nucleotides on the 5th and 11th-12th day of tumor growth. By contrast, content of nucleosides and bases were sharply decreased during the log growth phase (5th day) with the restoring of these precursors within the 11th-12th day (plateau phase). These observations indicate that aspects of the purine compounds metabolism in host erythrocytes are linked with tumor development.

Adenine Nucleotides↗