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Biomedical subjects

W Klinger

Publications and source records attributed to W Klinger.

At least 37 records · Page 2Linked to original sources
PubMed1998

Developmental changes of cytochrome P450 dependent monooxygenase functions after transplantation of fetal liver tissue suspension into spleens of adult syngenic rats.

Fetal liver tissue suspensions were transplanted into the spleens of adult male syngenic Fisher 344 inbred rats. Animals were sacrificed at 3 days, 1, 2, 4 weeks, and 2, 4 and 6 months after transplantation and cytochrome P450 (P450) dependent monooxygenase functions in spleen and liver 9000 g supernatants were assessed by measuring three model reactions for different P450 subtypes: ethoxyresorufin O-deethylation (EROD; mainly 1A), ethoxycoumarin O-deethylation (ECOD; predominantly 1A, 2A, 2B) and ethylmorphine N-demethylation (END; mainly 3A). Values of transplant recipients were compared to those of sham operated and age matched control rats. Spleen weights were significantly higher in transplanted rats, compared to controls or sham operated animals, but there was no influence of the transplants within the spleens on liver weights. With fetal livers at the 21st day of gestation, the day of transplantation, a weak EROD and ECOD, but no END activity was seen. Spleens of controls or sham operated animals displayed nearly no P450 mediated monooxygenase functions. In the explant containing spleens a significant and increasing EROD activity was found from 4 weeks after surgery on and an ECOD activity already 2 weeks after transplantation. END was only slightly enhanced at 6 months after surgery. The livers of all three groups of rats displayed normal EROD, ECOD and END activities. Transplantation of fetal liver tissue suspensions into the spleens did not influence the P450 dependent monooxygenase functions within the livers of the animals. From these results it can be concluded that intrasplenically transplanted liver cells originating from syngenic fetal liver tissue suspensions proliferate and differentiate within the host organs. They display P450 dependent monooxygenase functions with some developmental changes during the observed time period of 6 months.

Animals↗
PubMed1998

Luminol and lucigenin amplified chemiluminescence and lipidperoxidation with brain microsomes from rats during ontogenetic development.

The chemiluminescence (CL) amplifiers luminol (LM) and lucigenin (LC) react with different reactive oxygen species (ROS) in dependence on the ROS generating system used. With liver microsomes LMCL indicates predominantly superoxide anion radicals, whereas LCCL is mainly a measure for hydroxyl radical formation or of reactive organic radicals. With brain microsomes only LCCL, but not LMCL could be measured. For both brain microsomes from newborn (both sexes) and 60 day-old (male) rats LCCL is dependent on protein and NADPH concentration, activity in newborns being only 15% compared with young adult rats. As compared with liver microsomes 10-fold higher protein concentrations are needed to obtain comparable LCCL, whereas the NADPH demand is the same as with liver. A distinct ontogenetic development was demonstrated: low activities in the fetus, in newborn and 10-day-old rat are followed by higher activities with increasing age, after a maximum at an age of 60 days a decline was observed. Microsomal lipidperoxidation (LPO) was measured as formation of thiobarbituric acid reactive substances (TBARS) and was also dependent on protein and NADPH concentration. Unexpectedly, LPO with brain microsomes from newborn rats did not show any developmental variation.

Acridines↗
PubMed1998

[Cleavage and biotransformation of the central muscle relaxant chlormezanone].

Chlormezanone, a chiral centrally acting muscle relaxant, will be cleaved at its S-C-1 bond by an autoprotolytic process. The optimum of chemical stability exists between pH 2 up to pH 9 with a maximum at pH 7.4. The plasma half life at 37 degrees C is 76 h. Enzymes do attack the products of cleavage namely 4-chlorobenzaldehyde and 2-carboxyethane-sulfinic-acid-N-methyl-amide. The main metabolite in urine is 4-chlorohippuric acid in the range of up to 70% of the oral administered dose to humans. No cytochrome P-450 is engaged in the cleavage of the S-C-bond.

Biotransformation↗
PubMed1997

Influence of various estrogens on biotransformation: affinity to cytochrome P-450, structure activity relationships, and scavenger function.

Nine natural and synthetic estrogens all derived from endogenous 17 beta-estradiol, were tested for their affinity to cytochrome P-450 (P450). Binding spectra of the estrogens with rat liver microsomal P450 and inhibition kinetics with characteristic monooxygenase model reactions (ethylmorphine N-demethylation, EN, and ethoxycoumarin O-deethylation, EO) were determined. In addition, uncoupling effects and/or free radical scavenger functions were analysed by NADPH/Fe2+ stimulated microsomal luminol- and lucigenin-amplified chemiluminescense (CL). 17 beta-Estradiol, 17 alpha-ethynylestradiol, and D-estradiol 3-methyl ether inhibited both monooxygenase reactions of cytochrome P-450, whereas L-estradiol 3-methyl ether inhibited EO only. 17 beta-Estradiol, 17 alpha-ethynylestradiol, and D-estradiol 3-methyl ether seem to act as free radical scavengers. From the results both structure activity relationships could be established and data on possible interferences with drug metabolism obtained. The enantiomers D- and L-estradiol 3-methyl ether differ in their effects on these systems.

Animals↗
PubMed1996

Luminol-and lucigenin-amplified chemiluminescence with rat liver microsomes. Kinetics and influence of ascorbic acid, glutathione, dimethylsulfoxide, N-t-butyl-a-phenyl-nitrone, copper-ions and a copper complex, catalase, superoxide dismutase, hexobarbital and aniline.

For the investigation of luminol (LM)-and lucigenin (LC)-amplified chemiluminescence (CL) in rat liver microsomes using both a liquid-scintillation counter (LKB/Wallac 1219 Rackbeta) and a Berthold luminometer (AutoLumat LB 953) optimal incubation mixtures and conditions and basic kinetics have been established. Whereas calibration curves for both LM- and LC-CL are performed with hydrogenperoxide (LC quantum yield is 6.25 fold higher as that of LM), distinct differences were revealed with microsomes, indicating that different reactive oxygen species (ROS) are determined: Both LM- and LC-CL follow the kinetics of enzymatic reactions in terms of dependence on protein and NADPH or NADH concentration, time course, temperature etc., but with differences. LM-CL does not work without addition of Fe2+, whereas LC-CL does. Both copper ions and copper bound in a complex abolish CL, LC-CL being much more sensitive. Isolated cytochrome P-450 (P450) and NADPH P450 reductase from liver of pheno-barbital treated rats alone proved to be inactive in LM-and LC-CL production, whereas te combination 1:1 without and with addition of lipid was highly active in both LM-and LC-CL. Ascorbic acid and glutathione as scavengers diminish both LM- and LC-CL in concentrations higher then 10(5). Dimethyl-sulfoxide (DMSO) was ineffective in LM-CL up to concentrations of 0.2 M, the very high concentration of 2 M diminished LM-CL only to 1/3. LC-CL was diminished starting at concentrations of 100 mM and at 2 M only 10% of maximum LC-CL was observed. The trap substance N-t-butyl-a-phenylnitrone (BNP) also diminished LC-CL more effectively than LM-CL. Clearcut differences were revealed by the addition of catalase and superoxide dismutase: both enzymes diminished LM-CL only, without any influence on LC-CL. Hexobarbital, a potent uncoupler of P450, enhances LM-CL fivefold, whereas LC-CL is barely influenced. Aniline (without uncoupling capability) decreased both LM-and LC-CL increasingly with increasing concentrations. Therefore the conclusion is drawn that LM-CL measures in liver microsomes predominantly superoxide anion radicals, whereas LC-CL is mainly a measure for microsomal hydroxyl radical formation or of reactive organic radicals. With microsomes of phenobarbital and beta-naphthoflavone treated rats CL was much higher but in principle the same kinetic characteristics could be shown. All results on microsomes were obtained uniformly with the liquid scintillation counter and the Berthold luminometer, the letter being much more effective and more sensitive.

Acridines↗
PubMed1995

Nerval influences on liver cytochrome P450.

In male young adult Wistar rats the influences of nucleus raphe electrocoagulation, spinal cord dissection (cordotomy between C7 and Th1), vagotomy and denervation of liver hilus by phenol on liver cytochrome P450-system (cytochrome P450 concentration, ethylmorphine N-demethylation and ethoxycoumarin O-deethylation activities, hexobarbitone sleeping time) were investigated. In general the influences were small or negligible when compared with sham operated controls, only after vagotomy the depressing effect of sham operation was abolished. In all cases sham operation had a depressing effect until up to five weeks after operation.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1995

Influence of skin and muscle lesions on the hepatic cytochrome P450 function in 10 and 60 day-old male Wistar rats.

In 10 and 60 day-old male Wistar rats skin lesions of different extents and muscle lesions lead to decreases in cytochrome P450 concentrations and monooxygenase activities (ethylmorphine N-demethylation and ethoxycoumarin O-deethylation) at least up to 7 days after operation. The extent of the depression was related to the extent of the lesion and independent of the nature of the tissue involved.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1995

Brain peroxidative and glutathione status after moderate hypoxia in normal weight and intra-uterine growth-restricted newborn piglets.

In order to investigate the pathogenetic factors causing the relatively frequent occurrence of brain injury in intrauterine growth-restricted newborns, lipid peroxidation products (TBAR), glutathione (GSH, GSSG) and in vitro production of reactive oxygen species (chemiluminescence, stimulated lipid peroxidation, H2O2 formation) were studied in the brain of normal weight (NW) and intra-uterine growth-restricted newborn piglets (IUGR) after 1 hour of hypoxia (FiO2 11%) and 90 min reoxygenation. Cardiocirculatory parameters and catecholamine release into the blood were also measured. In the cerebellum, higher GSH content, but also higher in vitro production of lucigenin amplified chemiluminescence were found in comparison to other brain regions, independent of growth restriction and hypoxia. Moderate hypoxia without acidosis and hypercapnia resulted in GSH depletion especially in the brain of IUGR, but no changes in GSSG concentrations were measured. Though TBAR decreased after hypoxia/reoxygenation, in some brain areas of IUGR higher TBAR values were found in comparison to NW. H2O2 formation, stimulated lipid peroxidation and lucigenin and luminol amplified chemiluminescence in the 9000 x/g supernatant of brain tissue did not reveal special response of IUGR to hypoxia/reoxygenation. Hypoxia-induced circulatory centralisation due to increased release of catecholamines into the plasma prevented oxygen deficiency also in the brain of IUGR. The role of brain monoamine metabolism in the production of reactive oxygen species, followed by greater GSH depletion and higher in vivo formation of lipid peroxides in IUGR is discussed.

Animals↗
PubMed1994

Influence of the xanthine derivative denbufylline and the anti-inflammatory agent nabumetone on microsomal free radical production and lipid peroxidation in rat liver.

The influence of denbufylline, nabumetone and its main metabolite BRL 10,720 on iron stimulated lipid peroxidation (LPO), cytochrome P 450 dependent H2O2 and chemiluminescence (CL) production was investigated in rat liver microsomes in vitro (10(-5)-10(-3) M) and in vivo after treatment of rats (5-300 mg/kg b.m. orally on three consecutive days). In rat liver slices the release of thiobarbituric acid reactants (TBAR) was measured after 1 hour of incubation with the drugs. Denbufylline, nabumetone and BRL 10,720 exerted a significant inhibition of iron stimulated LPO in vitro. Nabumetone showed the strongest antioxidative activity, which was also seen in liver slices. These antioxidative effects were not found after in vivo treatment of rats. Denbufylline (10(-3) M) additionally inhibited H2O2 formation and the luminol and lucigenin amplified CL in vitro. Unexpectedly, nabumetone increased H2O2 formation both in vitro and in vivo, but in vitro only lucigenin amplified CL. BRL 10,720 increased microsomal H2O2 production in vivo. Moreover, BRL 10,720 enhanced CL in vitro and in vivo significantly, which is interpreted as an increase of the production of superoxide anion radicals and other reactive oxygen species such as H2O2, but lipid peroxidation in liver microsomes was not enhanced. These results suggest that denbufylline, nabumetone and BRL 10,720 in contrast to the in vitro effects did not exert antioxidative activities after treatment of rats. On the contrary, BRL 10,720 was found to support the formation of reactive oxygen species in liver microsomes.

Animals↗
PubMed1994

Peroxidative status and glutathione content of the brain in normal weight and intra-uterine growth-retarded newborn piglets.

The peroxidative and glutathione status as well as the production of reactive oxygen species were studied in the brain of normal weight (NW) and intra-uterine growth-retarded (IUGR) newborn piglets. In NW as well as IUGR newborn piglets reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxides, iron stimulated lipid peroxidation, H2O2 production and lucigenin and luminol amplified chemiluminescence are very similar in the different brain regions, with one exception. In the cerebellum, higher GSH concentration, higher superoxide anion generation, lower levels of lipid peroxides and a tendency toward a lower capacity of H2O2 production were seen. But the intra-uterine growth retardation to body weights of half the average body weights of the respective litter did not influence the peroxidative status and the GSH/GSSG equilibrium in the brain of newborn piglets.

Animals↗
PubMed1993

Age dependent different influence of carbon tetrachloride on biotransformation of xenobiotics, glutathione content, lipid peroxidation and histopathology of rat liver.

15- and 60-day-old male rats were treated with different doses of CCl4 orally. 24 h later cytochrome P-450 (P450) concentration, 7-ethoxyresorufin O-deethylation (EROD) and 7-pentoxy-resorufin O-deethylation (PEROD) activities were determined. Whereas P450 and EROD are lowered to the same extent in both ages, PEROD shows a more pronounced inhibition in the livers of younger rats. The formation of endogenous lipid peroxides (measured as thiobarbituric acid reactive substances) is drastically increased only in the livers of young rats. The hepatic glutathione (GSH) content was unaffected by CCl4 treatment whereas oxidized glutathione is more increased in the livers of adult rats. This can be caused by a higher activity of GSH-peroxidase in the livers of adult rats. The changes in NADPH-induced lipid peroxidation and chemiluminescence correlate partially with the changes in P450 and biotransformation reactions. Histopathologically the liver damage is more extensive in suckling rats. The necrosis is localized predominantly in the perivenous tissue, which has normally the highest activities of toxification and detoxification enzymes.

Age Factors↗
PubMed1993

Enzymes of glutathione synthesis in dog skeletal muscles and their response to training.

The glutathione synthesizing enzymes, gamma-glutamyl cysteinyl synthetase and glutathione synthetase, were found in all skeletal muscles studied in dogs. Both occurred also in the liver, but only the former in the lung. The influence of physical training on these enzyme activities was also investigated. For 30 weeks the dogs ran 5 days week-1 on a treadmill at a 15 degrees uphill grade. A 1.5- to 2-fold increase in the gamma-glutamyl cysteinyl synthetase and 3-fold increase in the glutathione synthetase activities was observed in muscles affected by the training procedure (m. triceps, m. extensor carpi radialis and m. gastrocnemius). No training effect could be observed in the splenius and longissimus dorsi muscles or in the liver. The training increased total glutathione levels in the lung and gastrocnemius muscle as well as in the plasma. Glutathione disulfide levels were not altered. Acute physical exercise significantly decreased the plasma total glutathione concentrations in the trained dogs. The results indicate a training responsive adaptation of glutathione system in skeletal muscle.

Animals↗
PubMed1992

The influence of systemic hypoxia and reoxygenation on the glutathione redox system of brain, liver, lung and plasma in newborn rats.

The concentrations of reduced (GSH) and oxidized glutathione (glutathione disulfide, GSSG) in lung, liver, brain and plasma of newborn rats were investigated under the condition of reversible hypoxia. Brain and lung of newborn rats seem to be susceptible to reversible hypoxia. We found an increase in GSSG concentration after hypoxia in these organs. This alteration of the GSH-GSSG redox system was reversible within 2 hours of reoxygenation. A second increase in cerebral GSSG concentration after 4 hours of reoxygenation was connected with fasting during the experiment. In the liver we found a hypoxia dependent decrease in the GSH level, followed by a decrease in GSSG concentration. The increased GSSG concentrations in lung and brain are accompanied by an enhancement of plasma GSSG concentration.

Animals↗
PubMed1992

Glutathione homeostasis in rats chronically treated with ethanol. Evidence for an increased hepatic GSH export in vivo.

The influence of chronic ethanol feeding to rats on the hepatic glutathione (GSH and GSSG) system (synthesis, catabolism, export) and on the GSH and GSSG concentrations in extrahepatic tissues was investigated. Histological examination of livers from ethanol pretreated rats revealed a minor dilatation of the hepatic sinusoids. After ethanol administration the distribution pattern of gamma-glutamyltranspeptidase (enzymehistochemistry) was nearly unchanged, but the hepatic activity of this enzyme was increased. The ethanol pretreatment led to a decrease in hepatic GSH content. The hepatic activity of the GSSG-reductase were increased after ethanol treatment whereas the activities of the GSH synthesizing enzymes (gamma-glutamyl-cysteinyl-synthetase and GSH-synthetase) were not affected. A strong increase in sinusoidal GSH export was found in the ethanol-pretreated rats. The GSH- and GSSG concentrations of brain, lung, kidney and skeletal muscle were unchanged. It can be concluded that the ethanol-induced alteration of the hepatic GSH metabolism is caused mainly by changes of the sinusoidal membrane of the hepatocytes (direct effect of ethanol on the sinusoidal GSH carrier) leading to an increased GSH export into plasma. This effect should not due to an increased extrahepatic requirement for GSH.

Animals↗
PubMed1992

Glutathione homeostasis and turnover in the totally hepatectomized rat: evidence for a high glutathione export capacity of extrahepatic tissues.

Glutathione (GSH) homeostasis and turnover were investigated in totally hepatectomized (HX) rats. A technique is described to remove the liver totally, with preservation of the hepatic portal and vena caval vasculature. Euglycemia could be maintained with hourly infusions of 50 mg 100 g-1 b.m. of glucose after bolus i.v. injection of glucose at the same dose. The efficiency of the animal model was demonstrated by examination of paraclinical blood parameters: progressive increases in total plasma bilirubin and alkaline phosphatase activity were noted after HX; the other parameters tested were predominantly in the normal range during the observation period of 6 hours. Histological examination revealed an acute but reversible impairment of intestine and kidneys. These results indicate that the surgical procedure and postoperative care were able to secure sufficient physiological conditions for the experiments over a longer period. 3 to 6 hours after HX we observed a decreased but stable plasma GSH level in anhepatic rats (about 50% of the control value). The GSH levels of brain and kidney were not changed. With increasing time period after HX the heart and lung GSH levels were depressed. A small depression of muscle GSH concentration was observed 4 and 6 hours after HX. A progressive increase in the concentration of oxidized glutathione was seen in brain and kidney. Our observations could be indicative for a high GSH export capacity of extrahepatic tissues contributing about 50% of the total GSH influx into circulation. Probably, the skeletal musculature is an important GSH origin for plasma.

Animals↗
PubMed1992

[Determining progesterone in saliva].

A radioimmunoassay for the determination of progesterone in saliva using a 125J-labelled progesterone derivate has been developed. The assay is characterized by the excellent sensitivity of 3.12 pg progesterone/ml. During the menstrual cycle of normal women the biphasic rhythm of progesterone in saliva could not been clearly demonstrated. In the follicle phase high peaks of progesterone have been shown and even in the luteal phase individual low values have been observed. The circadian rhythms of progesterone in saliva are characterized by irregular oscillations. The saliva flow rate is not responsible for the progesterone concentration. The measurement of progesterone in serum seems to be more useful in the diagnosis of sterility.

Adult↗