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O Tottmar

Publications and source records attributed to O Tottmar.

At least 37 records · Page 2Linked to original sources
PubMed1987

Metabolism of biogenic aldehydes in isolated human blood cells, platelets and in plasma.

The metabolism of biogenic aldehydes was measured in different human blood fractions. Isolated erythrocytes, leukocytes, platelets and plasma were incubated with 3,4-dihydroxyphenyl-acetaldehyde (DOPAL) or 5-hydroxyindole-3-acetaldehyde (5-HIAL), the aldehydes derived from dopamine and 5-hydroxytryptamine, respectively. The disappearance of the aldehydes and the formation of acid and alcohol metabolites were analysed using high-performance liquid chromatography with electrochemical detection. The aldehydes were unstable in phosphate-buffered saline, but this nonenzymatic oxidation was prevented in the presence of EDTA, pyrophosphate or blood tissue. When DOPAL or 5-HIAL were incubated with erythrocytes, only acid metabolites were formed, whereas both acid and alcohol metabolites were formed in incubations with leukocytes or platelets. The amount of the acid metabolite exceeded that of the alcohol metabolite, both with leukocytes and platelets. No metabolites were formed when the aldehydes were incubated in plasma. The oxidation of the aldehydes in incubations with erythrocytes or platelets was totally inhibited in the presence of 50 microM of the aldehyde dehydrogenase inhibitor disulfiram. However, disulfiram did not inhibit the metabolism of DOPAL and 5-HIAL in incubations with leukocytes, suggesting that different isozymes of aldehyde dehydrogenase are present in leukocytes as compared to erythrocytes and platelets.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Biogenic aldehydes in brain: on their preparation and reactions with rat brain tissue.

When 1 mM serotonin, dopamine, or norepinephrine was incubated with a monoamine oxidase preparation (mitochondrial membranes) in the presence of 4 mM sodium bisulfite, 85-95% of the amines were oxidized to the corresponding aldehydes. In the absence of bisulfite, the recoveries were only approximately 30%, and dark colored products were formed during the incubations. The aldehydes derived from tyramine, octopamine, methoxytyramine, and normetanephrine were also prepared by the use of this method. The bisulfite-aldehyde compounds were stable during storage at -20 degrees C. Bisulfite-free aldehyde solutions were made by diethylether extraction. When the aldehydes derived from dopamine or serotonin were incubated with rat brain homogenates, they were found to disappear in an aldehyde dehydrogenase- and aldehyde reductase-independent manner. The disappearance of the latter aldehyde was more pronounced, and the results indicated that this aldehyde may react with both proteins and phospholipids.

Aldehydes↗
PubMed1987

Metabolism of biogenic aldehydes in human blood: effects of ethanol, acetaldehyde and disulfiram.

The metabolism of biogenic aldehydes was measured in different fractions of human blood. Isolated erythrocytes, leukocytes, platelets and plasma were incubated with the aldehydes derived from dopamine and serotonin (DOPAL and 5-HIAL, respectively). The disappearance of the aldehydes and the formation of the acid and alcohol metabolites were analysed using HPLC with electrochemical detection. When erythrocytes were incubated with 1 microM DOPAL or 5-HIAL only the acid metabolites were formed, whereas both acid and alcohol metabolites were formed in incubations with leukocytes or platelets. No metabolites were formed when the aldehydes were incubated with plasma. In incubations with erythrocytes, the oxidation of the aldehydes was totally inhibited in the presence of 50 microM disulfiram, whereas the formation of both acid and alcohol metabolites was inhibited in incubations with platelets. Disulfiram did not affect the metabolism of DOPAL or 5-HIAL in incubations with leukocytes. The oxidation of the aldehydes was inhibited by 50-70% in the presence of a 500-fold excess of acetaldehyde. Ethanol at a concentration of 10 mM did not affect the metabolism.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Aldehyde dehydrogenase activity and vascular disease in type II diabetes--a comparison between 2 different assays for activity.

We have recently reported that type II diabetic subjects with macroangiopathy have a higher activity of aldehyde dehydrogenase (ALDH) in blood than those without clinical vascular disease. ALDH activity was measured as the elimination of acetaldehyde added to a blood homogenate in vitro. We have re-examined our clinical material with another assay of ALDH which uses indole-3-acetaldehyde as substrate and measures the formation of indole-3-acetic acid. A negative correlation between the half-life of acetaldehyde and the formation of indole-3-acetic acid was found in the group of subjects free from vascular disease (r = -0.55, p less than 0.01). Thus, a rapid elimination of acetaldehyde corresponded to a rapid formation of indole-3-acetic acid. No such correlation was found in subjects with macroangiopathy. These results suggest that the 2 groups, with and without clinical vascular disease, have differences in isoenzyme composition, in the kinetic properties of the enzyme, or in the non-enzymatic binding of acetaldehyde.

Aldehyde Dehydrogenase↗
PubMed1986

Assay of brain aldehyde dehydrogenase activity using high-performance liquid chromatography with electrochemical detection.

A method has been developed for assay of aldehyde dehydrogenase (ALDH) in brain tissue or in other tissues containing low ALDH-activity. The aldehyde of dopamine was used as the substrate, and the 3,4-dihydroxyphenylacetic acid formed was measured using high-performance liquid chromatography (HPLC) with electrochemical detection. The aldehyde was prepared enzymatically by incubating dopamine with a monoamine-oxidase preparation from rat liver mitochondria in the presence of Na+-bisulfite in 10 mM K+-phosphate buffer (pH 7.5). Rat brain homogenates were incubated in 50 mM Na+-pyrophosphate buffer (pH 8.8) containing 0.5 mM NAD+ and 5 microM aldehyde. The reaction was terminated with perchloric acid containing Na+-bisulfite to trap excess of the aldehyde. The acid supernatants were injected on a reverse-phase HPLC column and elution was performed with citrate buffer, pH 2.50. The method permits assay with 1-10 mg of brain tissue with an overall precision of 3%. The assay rate was 5-6 samples per hour.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Electrophysiological effects of monoamine-derived aldehydes on single neurons in neocortex and cerebellum in rats.

The electrophysiological effects of aldehydes derived from several monoamines were studied on single neurons in the cerebellum and neocortex of rats. The aldehydes derived from dopamine (3,4-dihydroxyphenylacetaldehyde) and serotonin (5-hydroxy-3-acetaldehyde) were prepared as stable disulfite complexes, from which free aldehydes were extracted. Serotonin and 5-hydroxy-3-acetaldehyde caused pronounced depression of firing rates both of cerebellar Purkinje neurons and neurons in prefrontal cortex. When locally applied from multibarrel micropipettes by pressure ejection, 5-hydroxy-3-acetaldehyde was twice as potent in the neocortex as in the cerebellum, and was equipotent with serotonin in both brain areas. The aldehyde of tryptamine also caused depressions of neuronal activity in cerebellum, but only at 5-fold higher doses than were effective for 5-hydroxy-3-acetaldehyde. 3,4-Dihydroxyphenylacetaldehyde was without effect in prefrontal cortex, but had mixed responses in the cerebellum. The results show that monoamine-derived aldehydes are physiologically active. It is possible that changes in the steady state level of these aldehydes caused by drugs such as ethanol and barbiturates might influence the electrophysiological properties of neurons in the central nervous system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

Biogenic aldehydes in brain: characteristics of a reaction between rat brain tissue and indole-3-acetaldehyde.

When indole-3-acetaldehyde was incubated with rat brain tissue, an aldehyde dehydrogenase-independent irreversible disappearance of the aldehyde was found. This was accompanied by an increase in absorbance at 240-400 nm, with a peak at 310 nm. The results suggested that this change in absorbance was caused by a membrane-bound nonenzymatic reaction between indole-3-acetaldehyde and phospholipids. A similar reaction occurred between indole-3-acetaldehyde and pure preparations of phosphatidylethanolamine and phosphatidylserine, but not phosphatidylcholine. Indole-3-acetaldehyde levels also decreased slightly when incubated with albumin but absorbance at 310 nm was unaltered. It is suggested that nonenzymatic reactions between indole-3-acetaldehyde (or other biogenic aldehydes) and membrane components might occur in vivo, and could be involved in the effects of drugs such as ethanol and barbiturates.

Albumins↗
PubMed1983

Studies in vitro on the inactivation of mitochondrial rat-liver aldehyde dehydrogenase by the alcohol-sensitizing compounds cyanamide, 1-aminocyclopropanol and disulfiram.

The inhibition of the low-Km, rat-liver mitochondrial aldehyde dehydrogenase (ALDH) by the alcohol-sensitizing agents cyanamide, 1-aminocyclopropanol (ACP) and disulfiram was studied in vitro. All three compounds caused a progressive decline in the enzyme activity. Restoration of activity could not be achieved by gel-filtration, dilution or by the addition of excess thiol. High concentrations of acetaldehyde partly restored the activity of the cyanamide-inactivated enzyme but had no effects on the disulfiram- or ACP-inactivated enzyme. In the presence of saturating concentrations of the coenzyme (NAD+), the inactivation process followed first-order kinetics at fixed concentrations of the inhibitors. Plots of the apparent first-order rate constants against inhibitor concentration were curved, suggesting the formation of saturable, reversible holoenzyme-inhibitor complexes prior to the covalent reactions. In the absence of NAD+, the rate of inactivation by disulfiram was biphasic and considerably higher than that in the presence of NAD+. In contrast, no inactivation was obtained with cyanamide in the absence of NAD+. Likewise, the presence of NAD+ greatly promoted the inactivation by ACP. The esterase activity of the enzyme was also affected by the inhibitors, although to a lesser extent than was the dehydrogenase activity. The results obtained suggest that all three inhibitors inactivate the enzyme through covalent reactions with the thiol groups at the active site. It is proposed that binding of NAD+ limits access of disulfiram to the thiols at the active site but provides a situation that favours an electrophilic attack of cyanamide and ACP on the thiol groups.

Aldehyde Oxidoreductases↗
PubMed1983

Aldehyde dehydrogenase in blood: a sensitive assay and inhibition by disulfiram.

The characteristics of human blood aldehyde dehydrogenase with indole-3-acetaldehyde as the substrate were investigated. Blood volumes of less than 25 microliter could be assayed. The Km-value was below 10 microM for indole-3-acetaldehyde and 100 microM for NAD+. The ALDH-activity appeared to be located exclusively in the intracellular fraction of the erythrocytes. Acetaldehyde or ethanol at concentrations up to 1 and 40 mM respectively did not affect the activity. Disulfiram caused a pronounced inhibition of the enzyme both in vitro and in vivo. The blood ALDH-activity in disulfiram-treated patients was not fully restored until 6 weeks after discontinuation of the treatment. The inhibition observed in vitro was reversed completely by 2-mercaptoethanol but only partially by glutathione. No restoration of activity in blood from disulfiram-treated patients was obtained with these two reagents. The inhibition found in vitro and in vivo was more pronounced when the assays were performed with indole-3-acetaldehyde than with acetaldehyde. The results suggest that different isozymes of ALDH are involved in the assay with these two substrates.

Adolescent↗
PubMed1983

Effects of oral administration or implantation of disulfiram on aldehyde dehydrogenase activity in human blood.

The general characteristics of the NAD-dependent aldehyde dehydrogenase (ALDH) present in blood were examined to find suitable assay conditions for activity measurements with whole blood samples from disulfiram-treated patients. The ALDH activity was measured as the rate of acetaldehyde disappearance. The ALDH activity in blood from alcoholics before disulfiram treatment was 39% lower than that found in blood from control subjects. Disulfiram caused a decreased ALDH activity in vitro. Similarly, a decreased activity was found in blood from patients treated with disulfiram orally (400 mg/day). The activity declined to a level being 60% of the control activity during the first week of treatment. A significant inhibition was observed 1 week after the treatment was discontinued. Implantation of 1 g of disulfiram in patients pretreated for 10 days with oral disulfiram did not cause a delayed return of ALDH activity, suggesting that the amounts of disulfiram released were too low to affect the ALDH activity in blood.

Acetaldehyde↗
PubMed1982

Effects of aldehyde dehydrogenase inhibitors on enzymes involved in the metabolism of biogenic aldehydes in rat liver and brain.

The effects of the aldehyde dehydrogenase inhibitors disulfiram, coprine and cyanamide on enzymes involved in the metabolism of biogenic aldehydes in rat liver and brain were studied. Both liver and brain aldehyde dehydrogenase activities were significantly decreased in rats pretreated with these drugs. In the liver, the low-Km aldehyde dehydrogenase activity was markedly decreased by all three drugs after 2 and 24 hr whereas only cyanamide inhibited the high-Km enzymes. The brain ALDH-activity with a low acetaldehyde concentration was significantly decreased by coprine and cyanamide at both times tested, whereas disulfiram caused no change after 2 hr but an inhibition of 38% after 24 hr. The brain ALDH-activity with a high acetaldehyde concentration was significantly decreased by coprine and cyanamide but not by disulfiram. The activity of the substrate specific enzyme succinate semialdehyde dehydrogenase in brain was slightly but significantly decreased in rats pretreated with cyanamide but not in rats pretreated with disulfiram or coprine. None of the drugs caused any changes in the activities of aldehyde reductase and monoamine oxidase in brains in vivo. The activity of monoamine oxidase in liver was significantly decreased by coprine after 24 hr. In contrast to the effects obtained in vivo, disulfiram was found to be an inhibitor in vitro of brain succinate semialdehyde dehydrogenase and liver monoamine oxidase. Aldehyde reductase was slightly inhibited by both disulfiram and 1-aminocyclopropanol in vitro.

Aldehyde Dehydrogenase↗
PubMed1982

Acute effects of ethanol and acetaldehyde on blood pressure and heart rate in disulfiram-treated and control rats.

The cardiovascular effects of ethanol and acetaldehyde were studied in control rats and rats pretreated with disulfiram. Ethanol administration to control rats decreased mean blood pressure and increased heart rate significantly. Injection of ethanol to disulfiram-treated rats decreased mean blood pressure, increases pulse pressure and increased heart rate and respiratory rate. The blood acetaldehyde levels were 10-15 times higher than those found in controls. The effects evoked by ethanol in disulfiram-treated rats were prevented or abolished in rats given 4-methylpyrazole before or after ethanol. Heart rate increased with increasing concentrations of acetaldehyde in control rats given acetaldehyde intravenously. Only a slight decrease in mean blood pressure was seen at high acetaldehyde levels (150-250 microM), whereas pulse pressure increased markedly as well as respiratory rate. At acetaldehyde levels lower than 50 microM, no effects on blood pressure were seen. The effects of acetaldehyde infusion in disulfiram-treated rats were similar to those observed in controls having comparable acetaldehyde levels. The results suggest that the disulfiram-ethanol reaction in rats is caused by the combined action of ethanol and acetaldehyde on the cardiovascular system.

Acetaldehyde↗
PubMed1982

Inhibition of aldehyde dehydrogenases in rat brain and liver by disulfiram and coprine.

Rats were treated with either coprine or disulfiram and the inhibition of aldehyde dehydrogenase (ALDH) in liver and brain mitochondria was measured with acetaldehyde, 3,4-dihydroxyphenylacetaldehyde (DOPAL), and succinate semialdehyde at different concentrations. The inhibition pattern was similar for both inhibitors, but the degree of inhibition was lower with disulfiram. The ALDH activity both in the liver and the brain was inhibited at low concentrations of acetaldehyde and DOPAL, but not with succinate semialdehyde. The high-Km enzyme activities with acetaldehyde were not inhibited in liver and brain. The activity at high concentration of DOPAL was inhibited in the liver, but only slightly affected in the brain, suggesting the presence of a brain enzyme with an intermediate Km value for DOPAL. In contrast with the results observed in vivo, it was found that the high-Km activities with acetaldehyde and DOPAL in brain mitochondrial preparations were more sensitive to the inhibitors in vitro than the low-Km activities. Kinetic studies on ALDH preparations from brain and liver mitochondria suggested that acetaldehyde and DOPAL are metabolized by the same low-Km ALDH.

Aldehyde Oxidoreductases↗
PubMed1982

Aldehyde dehydrogenases in rat brain. Subcellular distribution and properties.

Kinetic studies suggested the presence of several forms of NAD-dependent aldehyde dehydrogenase (ALDH) in rat brain. A subcellular distribution study showed that low- and high-Km activities with acetaldehyde as well as the substrate-specific enzyme succinate semialdehyde dehydrogenase were located mainly in the mitochondrial compartment. The low-Km activity was also present in the cytosol (less than 20%). The low-Km activity in the homogenate was only 10-15% of the total activity with acetaldehyde as the substrate. Two Km values were obtained with both acetaldehyde (0.2 and 2000 microM) and 3,4-dihydroxyphenylacetaldehyde (DOPAL) (0.3 and 31 microM), and one Km value with succinate semialdehyde (5 microM). The main part of the aldehyde dehydrogenase activities with acetaldehyde, DOPAL, and succinate semialdehyde, but only little activity of the marker enzyme for the outer membrane (monoamine oxidase, MAO), was released from a purified mitochondrial fraction subjected to sonication. Only small amounts of the ALDH activities were released from mitochondria subjected to swelling in a hypotonic buffer, whereas the main part of the marker enzyme for the intermembrane space (adenylate kinase) was released. These results indicate that the ALDH activities with acetaldehyde, DOPAL and succinate semialdehyde are located in the matrix compartment. The low-Km activity with acetaldehyde and DOPAL, but not the high-Km activities and succinate semialdehyde dehydrogenase, was markedly stimulated by Mg2+ and Ca2+ in phosphate buffer. The low- and high-Km activities with acetaldehyde showed different pH optima in pyrophosphate buffer.

Aldehyde Dehydrogenase↗
PubMed1982

Effects of dopamine-beta-hydroxylase inhibitors FLA-57 and FLA-63 on ethanol metabolism and aldehyde dehydrogenase activity in rats.

In rats pretreated with the dopamine-beta-hydroxylase (DBH)-inhibitors FLA-57 and FLA-63 (60 mg/kg, intraperitoneally, for 4 and 18 hrs), no effects on the blood acetaldehyde level after ethanol administration or on the activity of the low-Km aldehyde dehydrogenase (ALDH) in the liver were found. FLA-63 but not FLA-57 decreased the rate of ethanol elimination. FLA-63 inhibited the low-Km enzyme in vitro, but much less than the ALDH-inhibitors disulfiram and cyanamide. FLA-57 caused no inhibition in vitro. The results show that the previously observed suppression of ethanol intake in rats by FLA-57 and FLA-63 was not caused by an acetaldehyde-mediated aversion such as during the disulfiram-ethanol reaction.

Aldehyde Dehydrogenase↗
PubMed1981

Catecholamines in bovine semen.

In seminal plasma 5 x 10(-6) noradrenaline was found to induce head-to-head association in bull spermatozoa. The sum of noradrenaline and adrenaline in freshly collected semen was 10 ng/ml (5.2 x 10(-8) M), i.e., about 100 times lower than previously reported.

Animals↗
PubMed1980

Implantation of disulfiram in rats.

The biochemical and pharmacological effects of disulfiram implantation were studied in rats. Sterile disulfiram pellets (1000 mg/kg) were implanted subcutaneously. Groups of 5 rats were killed after 3, 7, 14, 28 and 56 days. The release of disulfiram during the first week corresponded to a daily dose of 12--16 mg/kg and during the following period to 5--8 mg/kg. The activity of the low-Km aldehyde dehydrogenase in liver and brain, the carboxylesterase activity in liver and the dopamine-beta-hydroxylase activity in heart were significantly decreased by approximately 45, 35, 20 and 35% respectively at all periods tested. The rate of ethanol elimination, the activity of monoamine oxidase in the brain, and the content of cytochrome P-450 in the liver were unaffected. The level of norepinephrine in the brain was slightly decreased after 14 days. The acetaldehyde level in blood after ethanol injection (1.0 g/kg) was 55--60 microM in the disulfiram group and 25--30 microM in the control group. Ethanol administration caused a slightly decreased blood pressure and increased respiratory rate 14 days after implantation but not after 28 days.

Acetaldehyde↗