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Biomedical subjects

H Esterbauer

Publications and source records attributed to H Esterbauer.

At least 127 records · Page 7Linked to original sources
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

Evidence for 4-hydroxyalkenals in rat renal cortex peroxidized by N2-methyl-9-hydroxyellipticinium acetate or Celiptium.

The antitumor drug celiptium is an ellipticine derivative whose nephrotoxic pathogenesis implicates a lipid peroxidation process. It has been shown that hydrophobic lipid deposits overload the proximal tubular cells. Histochemistry with Holczinger's technique has demonstrated that these deposits are free fatty acids. In this study, the fatty acid analysis of phospholipids and neutral lipids was performed in rat renal cortex 4 and 8 days following a single i.v. dose of 20 mg/kg celiptium and showed: (1) a loss of polyunsaturated fatty acids within total phospholipids and a loss of phosphatidylethanolamine with a preferential decrease of arachidonic (20:4) and docosahexaenoic (22:6) acids; (2) an increase of free fatty acid levels with an increase in oleic (18:1) and linoleic (18:2) acids; (3) an increase of thiobarbituric acid-reactive substances or aldehydes. The analysis of these aldehydes showed significant amounts of 4-hydroxyalkenals, mainly the presence of 4-hydroxynonenal on day 4 and of a hydroxyaldehyde with a chromatographic behavior very similar to 4-HNE on day 8. We conclude that celiptium induced a preferential decrease of phosphatidylethanolamine linked to the formation of unsaturated free fatty acids and of 4-hydroxyalkenals. The toxic side-effects of these breakdown products produced in the proximal tubular cell are discussed in light of the lipid peroxidation process involved in the renal toxicity of celiptium.

Aldehydes↗
PubMed1990

Effect of 4-hydroxylalkenals on hepatic phosphatidylinositol-4,5-bisphosphate-phospholipase C.

The effects of some 4-hydroxyalkenals, carbonylic products of lipid peroxidation, on hepatic phosphatidylinositol-4,5-bisphosphate (PIP2)-phospholipase C (PL-C) activity were investigated. The enzymatic activity was assayed in vitro by measuring the hydrolysis of [3H]PIP2 added as exogenous substrate to liver membranes. 4-Hydroxyhexenal (HEE), 4-hydroxyoctenal (HOE) and 4-hydroxynonenal (HNE) were able to stimulate both the basal and the GTPgammaS induced PL-C activity, whereas 4-hydroxyundecenal was inactive. HOE was the most active compound, being able to accelerate PIP2 breakdown at concentrations between 10(-12) and 10(-6) M, while in the case of HEE the effective doses ranged from 10(-11) to 10(-7) M and from 10(-9) to 10(-6) M in the case of HNE. 4-Hydroxynonenal was able to increase also bombesin stimulated PL-C activity. As these aldehydes accelerated PIP2 breakdown at doses which can be actually reached in tissues, the effects shown in vitro are likely to occur in vivo.

Aldehydes↗
PubMed1990

Detection of new epitopes formed upon oxidation of low-density lipoprotein, lipoprotein (a) and very-low-density lipoprotein. Use of an antiserum against 4-hydroxynonenal-modified low-density lipoprotein.

4-Hydroxynonenal (HNE) is a major aldehydic propagation product formed during peroxidation of unsaturated fatty acids. The aldehyde was used to modify freshly prepared human low-density lipoprotein (LDL). A polyclonal antiserum was raised in the rabbit and absorbed with freshly prepared LDL. The antiserum did not react with human LDL, but reacted with CuCl2-oxidized LDL and in a dose-dependent manner with LDL, modified with 1, 2 and 3 mM-HNE, in the double-diffusion analysis. LDL treated with 4 mM of hexanal or hepta-2,4-dienal or 4-hydroxyhexenal or malonaldehyde (4 or 20 mM) did not react with the antiserum. However, LDL modified with 4 mM-4-hydroxyoctenal showed a very weak reaction. Lipoprotein (a) and very-low-density lipoprotein were revealed for the first time to undergo oxidative modification initiated by CuCl2. This was evidenced by the generation of lipid hydroperoxides and thiobarbituric acid-reactive substances, as well as by a marked increase in the electrophoretic mobility. After oxidation these two lipoproteins also reacted positively with the antiserum against HNE-modified LDL.

Adult↗
PubMed1990

Influence of superoxide dismutase on staphylococcal arthritis--a histological and biochemical investigation using an experimental animal model.

The effect of superoxide dismutase (SOD) on staphylococcal arthritis has not been successfully evaluated to date. A suitable animal model has been developed to investigate a possible correlation. Using 16 rabbits divided into four groups, we injected the knee joints of two groups with Staphylococcus aureus and the other two with NaCl. One group in each of the two treatment groups was also injected with SOD. Blood samples and samples of joint fluid were taken at 12 hour intervals. Lipids were measured in plasma and joint fluid. The joints were examined macroscopically and microscopically using a scoring system to quantitate the deterioration of joint structures. Lipid peroxide concentrations measured in plasma differed in each of the groups, with higher values found in animals with septic arthritis compared with controls. The estimations made of lipid peroxide in joint fluid also displayed extreme variability, with the highest values found in animals with Staphylococcal arthritis treated with SOD. Histological examination also verified that the infected joints injected with SOD showed significantly more inflammation, a higher amount of bacteria in the joint cavity, and more distinct joint damage than joints injected only with bacteria. The mechanisms responsible for this SOD effect remain to be determined.

Animals↗
PubMed1990

Possible mutagens derived from lipids and lipid precursors.

Free radicals can initiate the oxidative decomposition of cellular membranes by lipid peroxidation. In this process a great variety of reactive aldehydes are produced intracellularly. Some of them, such as 4-hydroxynonenal or malonaldehyde, are biologically very active and might be involved in free radical-mediated DNA damage. A short review of the effects of aldehydic lipid peroxidation products on isolated DNA, their genotoxic effect in prokaryotes and eukaryotes and their in vivo carcinogenicity is given. Additionally own experiments on cytotoxic and genotoxic effects of 4-hydroxynonenal, 2-nonenal and nonanal in primary cultures of rat hepatocytes are reported. 4-Hydroxynonenal was highly cytotoxic at 100 microM, at subcytotoxic concentrations of 0.1-10 microM 4-hydroxynonenal increased the frequency of micronuclei, chromosomal aberrations and sister-chromatid exchange. 2-Nonenal and nonanal were not cytotoxic at 100 microM, the maximum dose tested. At 100 microM 2-nonenal led to a slight increase in micronuclei; chromosomal aberrations were not significantly altered. Nonanal had no detectable genotoxic effects. The level of endogenous 4-hydroxynonenal in tissues is in the range of 0.1-3.0 microM and can increase to 10 microM in conditions of oxidative stress; such levels appear to be sufficiently high to produce DNA damages, whether such damages are transient or irreversible is not known.

Aldehydes↗
PubMed1990

Cumene hydroperoxide, an agent inducing lipid peroxidation, and 4-hydroxy-2,3-nonenal, a peroxidation product, cause coronary vasodilatation in perfused rat hearts by a cyclic nucleotide independent mechanism.

STUDY OBJECTIVE - The aim of the study was to determine whether cumene hydroperoxide, a substance known to induce lipid peroxidation through free radical action, and 4-hydroxy-2,3-nonenal (4-hydroxynonenal), a major aldehyde formed during lipid peroxidation, induce coronary vasodilatation by changing cyclic nucleotide levels. DESIGN - The study involved Langendorff perfused rat hearts, using different concentrations of cumene hydroperoxide and 4-hydroxynonenal, with sodium nitroprusside for comparison. Coronary flow was measured indirectly as retrograde aortic flow, with constant perfusion pressure. Information about the precise localisation of cyclic guanosine monophosphate (cGMP) in the heart was obtained by immunocytochemistry, using a new cGMP antiserum. EXPERIMENTAL MATERIAL - Hearts were from male Wistar rats, body weight 200-250 g. MEASUREMENTS and RESULTS - Both cumene hydroperoxide and 4-hydroxynonenal caused a dose dependent and reversible increase in coronary flow comparable with sodium nitroprusside. With sodium nitroprusside there was a good correlation between extent of vasodilatation and total heart cGMP concentration. Vasodilatation induced by cumene hydroperoxide or 4-hydroxynonenal was not accompanied by increase in total heart cGMP or cAMP (cyclic adenosine monophosphate) concentration. Isoprenaline was used as a positive control for cAMP. cGMP immunostaining was found in coronary vascular smooth muscle after vasodilatation with sodium nitroprusside, but no immunostaining was found in vascular smooth muscle after vasodilatation with cumene hydroperoxide or 4-hydroxynonenal. CONCLUSIONS - Cumene hydroperoxide and 4-hydroxynonenal can provoke reversible coronary vasodilatation in isolated perfused rat hearts by a cyclic nucleotide independent mechanism.

Aldehydes↗
PubMed1990

Antioxidants and resistance against oxidation of porcine LDL subfractions.

The objective of this study was to determine the level of antioxidants, the content of fatty acids and peroxidation products, and the resistance against oxidation of native porcine LDL1 and LDL2. There were no significant differences in the fatty acid distribution of both native low density lipoprotein (LDL) subfractions, which was similar to that of human LDL. The total amount of alpha- and gamma-tocopherol of pig LDL was significantly lower than in human LDL, and beta-carotene, lycopene, and retinyl esters were totally absent. Levels of thiobarbituric acid-reacting substances (TBARS) and lipid peroxides in freshly isolated pig LDL subfractions were below or only slightly above the detection limit. The susceptibility to oxidation of both LDL subfractions was investigated by addition of Cu2+ as prooxidant. The results show that pig LDL subfractions are much more susceptible to oxidation as measured by the duration of the lag phase preceding the onset of rapid lipid peroxidation. From the low content of vitamin E one would expect even much shorter lag phases. The possibility therefore exists that pig LDL contains additional, and as yet unidentified, antioxidants.

Animals↗
PubMed1989

Promethazine inhibits the formation of aldehydic products of lipid peroxidation but not covalent binding resulting from the exposure of rat liver fractions to CCl4.

Promethazine is known to have protective activity in relation to CCl4-induced liver necrosis. This hepatoprotective property has been investigated with regard to the free radical scavenging and antioxidant properties of promethazine using isolated hepatocytes and microsomal suspensions. CCl4 is activated in both systems to free radical metabolites that bind covalently to lipid and protein, and initiate lipid peroxidation. A large number of carbonyl products is produced during CCl4-induced lipid peroxidation; promethazine strongly inhibits the production of all classes of carbonyl compounds in both microsomal suspensions and isolated hepatocytes. In contrast, promethazine is a very weak inhibitor of the covalent binding of metabolites of CCl4. We conclude that promethazine acts by scavenging the trichloromethylperoxyl radical and lipid peroxyl radicals, and is a weak scavenger of the trichloromethyl radical. These data, when considered together with the hepatoprotective effects of promethazine, suggest that lipid peroxidation is of relatively more importance than covalent binding in the pathogenesis of CCl4-induced liver necrosis.

Aldehydes↗
PubMed1989

Monoclonal antibodies against different domains of cellobiohydrolase I and II from Trichoderma reesei.

Monoclonal antibodies have been produced against two functionally different domains present in two cellobiohydrolases from Trichoderma reesei (CBH I and CBH II). Four groups of antibodies were obtained, which specifically recognized (Western blotting, ELISA) (a) the core protein within CBH I, (b) the core protein within CBH II, (c) the BA region of CBH I, and (d) the ABB' region of CBH II. No cross-reactivities within these four groups were observed. The antibodies reacted also specifically with proteins of similar size to CBH I and CBH II (SDS-PAGE) from other Trichoderma strains (Western blotting), whereas no reaction was observed with cellulases from other fungal sources. Analysis of culture filtrates of T. reesei QM 9414 harvested at various times of growth on cellulose under buffered conditions (pH 5-6) indicated the presence of only single bands of CBH I and CBH II, even after prolonged cultivation (160 h). Cultivation on cellulose in unbuffered media, however, showed the appearance (Western blotting) of additional lower molecular weight proteins, which reacted with the monoclonal antibodies directed against the cores of CBH I and II, but not with those recognizing the respective BA and ABB' regions. The appearance of these lower molecular weight bands was most pronounced in unbuffered media, supplemented with a 3-fold (w/w) amount of organic nitrogen (peptone). Analysis of some commercial cellulase preparations from T. harzianum revealed the same pattern of lower molecular weight proteins, in contrast to samples from other fungal cellulases. Those samples or preparations, showing a multiple pattern of CBH I and CBH II, exhibited higher activities of an acid proteinase. These results imply that the use of unbuffered, high nitrogen-supplemented culture conditions for production of cellulases may lead to considerable proteolytic modification of the secreted cellobiohydrolases.

Antibodies, Monoclonal↗
PubMed1989

Methods for determination of aldehydic lipid peroxidation products.

A complex pattern of aldehydes (alkanals, 2-alkenals, 2,4-alkadienals, 4-hydroxyalkenals) is generated by peroxidizing biological samples. Several methods based on HPLC or GC-MS have been developed to qualitatively and quantitatively measure the aldehydes in tissues, cells and cell fractions exposed to various pro-oxidative stimuli. 4-Hydroxynonenal, hexanal and propanal are, besides malonaldehyde, the most abundant aldehydes formed. The high sensitivity of the methods also allows the measurement of physiological aldehyde levels in plasma or low density lipoproteins and this could be of great importance for in vivo studies.

Aldehydes↗
PubMed1989

Continuous monitoring of in vitro oxidation of human low density lipoprotein.

The kinetics of the oxidation of human low density lipoprotein (LDL) can be measured continuously by monitoring the change of the 234 nm diene absorption. The time-course shows three consecutive phases, a lag-phase during which the diene absorption increases only weakly, a propagation phase with a rapid increase of the diene absorption and finally a decomposition phase. The increase of the dienes is highly correlated with the increase of MDA or lipid hydroperoxides. The duration of the lag-phase is determined by the endogenous antioxidants contained in LDL (vitamin E, carotenoids, retinylstearate). Water-soluble antioxidants (ascorbic acid, urate) added in micromolar concentrations prolong the lag-phase in a concentration-dependent manner. The determination of the lag-phase is a convenient and objective procedure for determining the susceptibility of LDL from different donors towards oxidation as well as effects of pro- and antioxidants.

Adult↗
PubMed1989

Cytotoxic effects of 6-hydroxydopamine, merocyanine-540 and related compounds on human neuroblastoma and hematopoietic stem cells.

6-Hydroxydopamine(6-OHDA) and Merocyanine-540(MC-540) have been used clinically for purging of neuroblastoma cells prior to autologous bone marrow transplantation. Both substances were found to be more toxic against neuroblastoma cells than against hematopoietic stem cells. The more pronounced cytotoxic effects of 6-OHDA against neuroblastoma cells were not caused by its selective uptake; the rapid autooxidation at physiological pH leads to the formation of H2O2 already in the incubation medium. Cytotoxic effects were not detected in short-time test systems (4 hour chromium-51 release assay) but only after longer incubation periods. In contrast, MC-540 proved to be toxic almost equally in short- and long-time test systems. 4-Hydroxynonenal(4-HNE) that may be formed in the plasma membrane subsequently to photoactivation of MC-540 was only slightly more toxic to neuroblastoma cells than to hematopoietic cells. Although the use of 6-OHDA and MC-540 in bone marrow purging has some limitations, the sensitivity of neuroblastoma cells against reactive oxygen compounds may be exploited more generally for therapy of this tumor.

Aldehydes↗
PubMed1989

Staphylococcal arthritis--effects of superoxide dismutase on infected knee joints of rabbits.

The effect of SOD on staphylococcal arthritis has not been successfully evaluated to date. We developed an animal model to investigate the correlation. Using 16 rabbits divided into four groups, we injected two groups with staphylococcus aureus and the other two with NaCl. One group in each was also injected with SOD. The presence of SOD activity in untreated and infected knee joints of rabbits over a period of 72 hours showed no significant difference. TBA-reactive substances (TBARS) measured in joint fluid and plasma did differ in each of the groups, with the highest values found in animals with septic arthritis treated with SOD. This finding corresponded especially with the histological investigation. Joints of infected animals intra-articularly injected with SOD also showed histologically significantly more inflammation, a higher amount of bacteria in the joint cavity, and more distinct joint damage than joints injected only with bacteria. The mechanisms responsible for this SOD effect remain to be determined.

Animals↗