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W Augustin

Publications and source records attributed to W Augustin.

At least 37 records · Page 2Linked to original sources
PubMed1996

Isolation of functionally intact pig retina mitochondria.

Two alternative methods for the isolation of functionally intact mitochondria from pig retina were evaluated by means of differential centrifugation. If ATP and bovine serum albumin were present during the isolation procedures mitochondria exhibited ADP sensitive respiration and membrane potentials, comparable to values from other tissues. The mitochondria fraction of both methods differed in purity, being almost free of synaptosomes when a discontinuous Ficoll gradient centrifugation was used.

Animals↗
PubMed1996

Improved method for studying skin lipid samples from cyanoacrylate strips by high-performance thin-layer chromatography.

A non-invasive method for sampling skin surface lipids is cyanoacrylate stripping (CAC-TS). It was the purpose of our study to improve the method for sampling of skin surface lipids and the separation of epidermal lipid fractions by a modification of the methods described by Melnik and by Imokawa et al. Briefly, lipids on the glass slide sampled by CAC-TS from the forearm of 75 volunteers and from the forehead of 60 volunteers were eluted in hexane/ethanol under ultrasonication. Identification of the diluted total superficial sebaceous and epidermal skin lipids was performed by sequential high-performance thin-layer chromatography. For quantification of the lipids we used densitometric methods. By this modified method we were able to show a clear and complete separation of all relevant lipids from a cyanoacrylate strip that represented 1-2 mg stratum corneum only.

Cell Fractionation↗
PubMed1995

Electrophoretic evidence for the impairment of complexes of the respiratory chain during iron/ascorbate induced peroxidation in isolated rat liver mitochondria.

The impairment of the complexes of the respiratory chain was studied in isolated rat liver mitochondria under the conditions of an iron/ascorbate-mediated oxidative stress. Using blue native electrophoresis technique the NADH-ubiquinone oxidoreductase, ubiquinol-cytochrome-c oxidoreductase, cytochrome oxidase and ATP-synthetase were separated from mitochondrial samples at different stages of peroxidation and quantified by densitometry. In the second dimension the protein complexes were separated into their individual subunits by Tricine/SDS-electrophoresis. In relation to the time course of lipid peroxidation protein losses were moderate in the exponential phase and enhanced towards plateau phase of TBARS formation, when the intensity of staining for the native complexes became reduced by 84%, 69%, 63% and 24% for complexes I, III, V and IV, respectively, and a high molecular aggregation band as a putative marker of oxidative stress was formed. The decline of overall staining by 23%, a decrease in trichloroacetic acid precipitable protein and the formation of acid soluble primary amines suggest the occurrence of fragmentation or degradation processes. Apparently, the impairment of the respiratory chain complexes during peroxidation was not reflected in altered electrophoretic mobilities or specific losses of protein subunits of these innermitochondrial membrane components.

Animals↗
PubMed1995

Effects of trapidil on the PGI2 and TXA2 synthesis in human umbilical veins perfused in vitro.

Current therapeutical concepts for prophylactic treatment of preeclampsia are based on the hypothesis that this pathological state is mainly due to a functional imbalance between vascular prostacyclin (PGI2) and thromboxane A2 (TXA2) biosynthesis. The influence of Trapidil on PGI2 and TXA2 formation was studied by in vitro perfusion of human umbilical veins by measuring the production of the metabolites 6-keto-PGF1 alpha and TXB2, respectively, in the perfusates using Enzyme-Immunoassay. The basal production of 6-keto-PGF1 alpha was 90.6 pg/mL/cm of vessel wall, whereas TXB2 formation attained a rate of 7.5 pg/mL/cm. The addition of Trapidil to the perfusate resulted in a significant stimulation of PGI2 production but apparently does not exhibit any effect on TXB2 generation. These data support the suggestion that Trapidil may act by increasing the ratio of PGI2/TXA2 in favor of the antiaggregatory/vasodilatory PGI2.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

[Effect of trapidil in prevention of pre-eclampsia and fetal retardation].

Pre-eclampsia is suggested to be characterized by a functional imbalance between vascular prostacyclin and thromboxane A2 production. On the basis of this hypothesis it is attempted to correct this pathologic conditions by pharmacological manipulation with Trapidil, a triazolo pyrimidin derivative, because of its effects on the prostanoid metabolism. A prospective, randomized, double blind, placebo-controlled study was carried out to investigate Trapidil in the prevention of pregnancy-induced hypertension or pre-eclampsia. A total of 160 pregnant women with the risk to develop pre-eclampsia received Trapidil or placebo between week 24 and 38 of gestation. The number of patients in whom pregnancy-induced hypertension or pre-eclampsia developed was significantly lower in the Trapidil-treated (5.5%) compared with the placebo-treated group (14.1%). Additionally, a reduced risk of preterm deliveries and severe fetal growth retardation could be observed. In 7 patients with manifest pre-eclampsia or pregnancy-induced hypertension the circulating eicosanoid concentrations were determined before and during Trapidil medication. Trapidil was associated with an about twofold increase of 6-keto PGF1 alpha concentration in the peripheral venous blood, while the concentration of thromboxane A2 revealed no changes.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

A new animal model of dopamine supersensitivity using s.c. implantation of haloperidol releasing polymers.

Dopamine supersensitivity was induced by either the continuous daily release of 1.0 mg/kg haloperidol from controlled release polymers implanted subcutaneously in rats or by daily bolus injection. In vitro, these polymers were found to release haloperidol for more than 250 days. After implantation in vivo, supersensitivity was quantified by locomotor activity following apomorphine injection and specific [3H]spiroperidol binding to striatal synaptic membranes. Supersensitivity in rats with haloperidol implants was remarkably similar to that evoked by daily drug applications after 3 weeks without producing the detrimental daily sedations, typically seen after bolus administration. Furthermore, no difference in specific binding between both group was seen. A continuous delivery of haloperidol for 8 weeks also resulted in comparable denervation supersensitivity. Controlled release polymers may thus be a superior tool to induce denervation supersensitivity in a gradual, continuous fashion.

Animals↗
PubMed1994

Relations between tocopherol depletion and coenzyme Q during lipid peroxidation in rat liver mitochondria.

In order to evaluate different mitochondrial antioxidant systems, the depletion of alpha-tocopherol and the levels of the reduced and oxidized forms of CoQ were measured in rat liver mitochondria during Fe++/ascorbate and NADPH/ADP/Fe++ induced lipid peroxidation. During the induction phase of malondialdehyde formation, alpha-tocopherol declined moderately to about 80% of initial contents, whereas the total CoQ pool remained nearly unchanged, but reduced CoQ9 continuously declined. At the start of massive malondialdehyde formation, CoQ9 reaches its fully oxidized state. At the same time alpha-tocopherol starts to decline steeply, but never becomes fully exhausted in both experimental systems. Evidently the oxidation of the CoQ9 pool constitutes a prerequisite for the onset of massive lipid peroxidation in mitochondria and for the subsequent depletion of alpha-tocopherol. Trapping of the GSH by addition of dinitrochlorbenzene (a substrate of the GSH transferase), results in a moderate acceleration of lipid peroxidation, but alpha-tocopherol and ubiquinol levels remained unchanged when compared with the controls. Addition of succinate to GSH depleted mitochondria effectively suppressed MDA formation as well as alpha-tocopherol and ubiquinol depletion. The data support the assumption that the protective effect of respiratory substrates against lipid peroxidation in the absence of mitochondrial GSH is mediated by the regeneration of the lipid soluble antioxidants CoQ and alpha-tocopherol.

Animals↗
PubMed1994

Haloperidol-induced behavioral supersensitivity is increased by monosialoganglioside treatment in rats without affecting spiroperidol-binding.

In rats, dopamine supersensitivity was induced by haloperidol (HAL) treatment for 3 weeks, either by implanted polymer matrices or by daily i.p. injections (1.0 mg/kg/day). Thereafter, dopamine supersensitivity was tested by measurement of motor activity of the animals after application of the dopamine agonist apomorphine (0.5 mg/kg i.p.) and by determination of the specific D2 dopamine binding sites in the corpus striatum by using [3H]spiroperidol. In both modes of HAL administration, no differences were found in the behavioral and neurochemical parameters. The apomorphine-induced motility was enhanced, and the known up-regulation of the striatal D2 dopamine binding was detected. When monosialoganglioside (GM1) was given daily i.p. for 3 weeks parallel to HAL application, dopamine supersensitivity, as indicated by the apomorphine-induced motility, was enhanced significantly without affecting the striatal D2 dopamine receptor up-regulation. In a subsequent experiment, we reduced the HAL dose and observed the expected D2 dopamine up-regulation. However, GM1 had no effect either on striatal D2 dopamine binding or on motility. A thin-layer chromatography analysis revealed that the endogenous gangliosides pattern in the corpus striatum also remained unchanged after HAL treatment. In conclusion, GM1-induced elevation of behavioral supersensitivity cannot be explained by a direct interaction with the D2 dopamine receptor, but other mechanisms may be involved, such as the modification of second messenger pathways.

Animals↗
PubMed1993

Quantitative analysis of retinal vessel changes in galactose-fed dogs.

Retinal vessel changes in 36-month 30% galactose-fed beagles treated with or without aldose reductase inhibitors were quantified using an Olympus Cue-3 color image analysis system. Individual maps of the intact retinal vasculature, isolated by trypsin-digestion, were divided into 24 distinct subregions and measurements of either the endothelial cell to pericyte (E/P) ratio or cell densities, expressed as pericytes per mm capillary length or endothelial cells per mm capillary length, were conducted in 0.1 mm2 areas surrounding the midpoints of 12 subregions associated with the highest incidence of microaneurysms. Significantly increased E/P ratios and decreased pericyte densities were observed with the duration of galactose-feeding. These retinal changes were reduced by aldose reductase inhibitor treatment. Correlations between the E/P ratio and either number of microaneurysms or cataract severity were also observed. These data support the dose-dependent effects of aldose reductase inhibitors in preventing pericyte degeneration and subsequent formation of microaneurysms (Archives Ophthalmol. 108:1301, 1990).

Aldehyde Reductase↗
PubMed1992

Evaluation of a procedure for the simultaneous determination of oxidized and reduced pyridine nucleotides and adenylates in organic phenol extracts from mitochondria.

An extraction procedure using mixtures of phenol, chloroform, and isoamyl alcohol originally applied to quench mitochondria for determining adenylates proved suitable also for the quantification of reduced and oxidized pyridine nucleotides yielding recoveries of more than 90%. In combination with HPLC, this approach allows the simultaneous determination of NAD+, NADP+, NADH, and NADPH as well as of adenylates within one extract. A comparison of this extraction method with fluorimetric measurements of pyridine nucleotide reduction in intact mitochondria revealed that about 30% of the fluorescence signal in the resting state of liver mitochondria is caused by NADPH.

Adenine Nucleotides↗
PubMed1991

Prediction of total body lipid from total body water in rats. Part 1. Relations between directly measured major body components.

Aimed to the construction of a prediction equation for estimations of lipid content from animal water content body composition was determined by whole body analysis of male rats (1) given access, ad libitum, to a commercial standard diet (n = 144; ranging from 60 to 600 g in weight, and from the 4th to the 34th week of age), and (2) showing striking variations with regard to nutritional state, dietary history, enlarged fat deposition, genetic origin, intestinal microbial status, and advanced age (n = 75). It was shown that a unique coefficient of water content in lipid-free body mass does not exist. The results of statistical analysis for the grouped values of percentage body dry matter (x) and percentage body lipid (y) indicate that the latter can be estimated accurately from body water content directly determined by the use of the quadratic regression equation y = -0.2864 x +0.01615 x2 with a standard deviation of the procedure Sy = +/- 1.40. This prediction equation is valid for a wide developmental span even under highly different experimental states. Differences between the calculated body lipid contents vs. analytically determined values are smaller than by using a linear regression equation or coefficient(s) of hydration of lipid-free body mass.

Aging↗
PubMed1991

Prediction of total body lipid from total body water in rats. Part 2. In vivo estimation of total body lipid by tritium water dilution.

Body composition data estimated for normal young, normal adult, and adult obese Wistar rats by a tritiated water (THO) dilution procedure (b. wt. range 119-237 g, n = 31; 305-597 g, n = 43; 274-381 g, n = 6) were compared with the results of whole body analysis. As for the predicted total body lipid (TBL), the content was calculated from the virtual THO-dilution space estimated by a simple micro-method and a regression equation between TBL [%] and DM [%] (dry matter) content (Part 1. Relations between directly measured major body components. Nahrung 35 (1991) 581. Due to different degrees of overestimations in the animal groups examined, the THO-space can be corrected via subtraction of 3.8%, 2.2% and 1.1% in the sequence young, obese, and adult groups. The derived TBL [%] data show a non-significant deviation of less than 1 g/100 g b. wt. in comparison to the three group means after direct lipid determinations. In the best case, i. e. after the additional elimination of extremely overestimated values for total body water (outliers) the combined tritium-derived lipid values (y) are correlated with the lipid data obtained analytically (x), both as proportion of the body weight, by the regression equation y = 0.848 + 0.963 x, r = 0.985, Sy.x = 1.77, n = 58. For a group of young rats (n = 14) after a pre-experimental supplementation with a sucrose solution, TBL values, not significantly different from analytically determined ones, could be calculated without any corrections.

Animals↗
PubMed1991

Morphological changes of isolated rat liver mitochondria during Fe2+/ascorbate-induced peroxidation and the effect of thioctacid.

Fe2+/ascorbate-induced peroxidation of isolated rat liver mitochondria leads to initial volume changes and, ultimately, to severe damage characterized by gross swelling and loss of cristae and matrix material. Only the last phase is associated with significant production of malondialdehyde. The shrinkage of mitochondria during the onset of peroxidation matches changes observed in mitochondria of aging animals. Thioctacid (alpha-lipoic acid) prevents this initial shrinkage. However, its main effect in the system studied here is inhibition of active respiration.

Animals↗
PubMed1989

Flux control coefficients for Pi- and adenine nucleotide translocator in rat liver mitochondria after Fe2+/ascorbate induced oxidative stress.

In the early phase of iron/ascorbate induced peroxidation in rat liver mitochondria a progressively diminished active and uncoupled respiration, likely caused by an attack at the level of the respiratory chain was established, whereas the transmembrane potential (delta psi) under phosphorylating conditions did, however, not reflect this inhibition. A tentative explanation for this behaviour was suggested on the basis of an impairment of both membrane potential generating and consuming processes. By measurements of the velocity of mitochondrial 32Pi-uptake during the time course of peroxidation an inhibition of the Pi-carrier was detected. The calculated flux control coefficients for the Pi- and ATP/ADP-translocator indicate that the last one exerts a large control independent on the respiration rate during the initial phase of peroxidation. The data show that the predominant step in the control of oxidative phosphorylation at the site of the consumers must be attributed to the ATP/ADP-exchanger.

Animals↗
PubMed1989

The role of mitochondrial glutathione in the defence against Fe2+/ascorbate induced peroxidation of rat liver mitochondria.

The protective role of the glutathione system against oxidative stress was studied in the model of Fe2+/ascorbate induced peroxidation in isolated rat liver mitochondria. There was a successive diminution of the mitochondrial glutathione pool, essentially due to losses of the reduced form (GSH) during the initiation phase of peroxidation, while the redox state of glutathione was not influenced significantly before the onset of massive malondialdehyde formation. Oxidizable substrates such as glutamate/malate and 3-hydroxybutyrate affected peroxidation by extending the period of the induction phase. Obviously that was due to the supply of NADPH to recover GSH via GSSG-reductase as evidenced by the parallel decline of the NADP(H) and the glutathione-system redox states. Although the data strongly support the fact that mitochondrial glutathione plays a central role in the defence against oxidative stress, there are, under special conditions of a high succinate supply, other potent defence systems in isolated mitochondria.

Animals↗
PubMed1989

Studies of lipid peroxidation in isolated rat heart mitochondria.

Peroxidation in isolated, functionally intact rat heart mitochondria was induced by iron/ascorbate or ADP-iron/NAD(P)H. Compared to liver mitochondria, MDA formation was very low and lipohydroperoxides not detected. The NADPH-mediated peroxidation which generally resulted in somewhat higher MDA levels was accompanied by an increasing inhibition of ADP-stimulated respiration. The active respiration was sensitively inhibited at very early stages of MDA formation, whereas in the same period the CAT-insensitive respiration exhibited almost no response at all. It was demonstrated that the decrease in active respiration correlated with the time for half-maximum MDA formation. No considerable degradation of major mitochondrial phospholipids was observed during two hours of incubation. It was not until after complete inhibition of respiration and onset of enhanced MDA formation that cardiolipin, phosphatidylethanolamine and, later, phosphatidylcholine were diminished.

Adenosine Diphosphate↗
PubMed1988

Injury of mitochondrial respiration and membrane potential during iron/ascorbate-induced peroxidation.

First functional events during peroxidation in mitochondria consisted in a progressive inhibition of the phosphorylating and uncoupled respiration with succinate and glutamate/malate as substrates, whereas the resting state respiration during the same period was virtually not influenced. The membrane potential registered at a time with the respiration rates was capable of being built up for a relatively long time interval with only minor decreases, and broke down rather promptly when the active respiration was highly diminished. Inhibition of respiration proceeded mainly during the initiation phase of peroxidation. Lag phases of varied length, of malondialdehyde formation which were predominantly attributed to the iron/protein ratios correlated closely with different time intervals needed to attain maximal inhibition of respiration and decrease in glutathione. Hence, the lessening of respiration, drop of membrane potential and loss of the antioxidant, glutathione, represent early stages in the causal chain of events which precede the onset of intensive lipid peroxidation.

Animals↗