Abstract: The metabolism of [1,2-14C]vinyl bromide (VBR) to products irreversibly bound to DNA and protein was examined in rat liver microsomes, reconstituted cytochrome P-450 systems, and isolated hepatocytes. A role for cytochrome P-450 was confirmed using inhibition and reconstitution experiments. The major form of cytochrome P-450 involved in VBR metabolism does not appear to be either of the major isozymes induced by phenobarbital or beta-naphthoflavone, as determined by induction, reconstitution, and antibody inhibition studies. 2-Bromoethylene oxide and 2-bromoacetaldehyde, suspected metabolites of VBR, were synthesized and found to be substrates for rat liver epoxide hydrolase and equine liver alcohol dehydrogenase, respectively. These enzymes were used to probe the roles of the two possible metabolites in the irreversible binding of products of VBR to protein and DNA. Alcohol dehydrogenase was more effective than epoxide hydrolase in inhibiting the binding of VBR metabolites to protein in microsomal incubations. Epoxide hydrolase was effective in inhibiting the binding of VBR or vinyl chloride metabolites to calf thymus DNA added to such systems, but alcohol dehydrogenase was not. Similar results were obtained for binding of VBR metabolites to DNA in a reconstituted enzyme system. Reduced glutathione blocked nonenzymatic binding of 2-bromo[1,2-14C]acetaldehyde to protein but not DNA. Binding of vinyl chloride and VBR metabolites to protein was blocked by reduced glutathione, but binding to DNA was not. These results are consistent with the view that 2-haloethylene oxides are the major alkylating agents bound to DNA, and 2-haloacetaldehydes are the major alkylating agents bound to protein in these experimental systems. Studies with labeled 2-bromoacetaldehyde indicate that the slow kinetics of DNA binding by this compound is responsible in part for this phenomenon. Studies with isolated rat hepatocytes suggest that a significant portion of the total and reactive metabolites are able to leave these cells. In these systems, binding of metabolites of vinyl chloride to DNA outside the hepatocytes could be partially blocked by epoxide hydrolase or by alcohol dehydrogenase, implying that, as target farther away from sources of reactive species are considered, the stabilities of these species become more important for reaction with nucleophilic sites.

Abstract: Incorporation of 3H-thymidine into DNA was significantly diminished by treatment with ethanol and acetaldehyde in regenerating rat liver, rat ceils in culture, and rat fetal tissues. Reduced incorporation was especially marked in the fetal central nervous system and was observed with both compounds at levels similar to those reported to occur in human alcoholics. The reduced incorporation of 3H-thymidine into fetal DNA, together with the increased fetal mortality observed in dams treated specifically with acetaldehyde during pregnancy, suggests that acetaldehyde is implicated in the mechanism of teratogenesis associated with the fetal alcohol syndrome.

Abstract: Deterioration as evidenced by decline in germination or seedling growth of soybean (cv. Essex) seeds during accelerated aging treatments at 41 C and 100% relative humidity is accompanied by increased levels of acetaldehyde and ethanol in imbibing embryonic axes and seeds. These increases become more pronounced with duration of the aging treatment. A similar inverse relationship between levels of acetaldehyde and ethanol and deterioration was observed when seeds were “naturally” aged for several years. During imbibition of low-vigor, accelerated-aged seeds at 25 C, acetaldehyde and ethanol increased from near trace amounts in dry tissues to maximum levels at 4 hours. Increases in acetaldehyde and ethanol during imbibition were less in high- than in low-vigor seeds. Increases were also less pronounced in low-vigor seeds when water uptake injury was avoided by osmotically decreasing water uptake rate with 30% polyethylene glycol. Embryonic axes from deteriorated seeds were characterized by low rates of O2 uptake and high respiratory quotients relative to the unaged controls. Anaerobic conditions and respiratory inhibitors, such as sodium azide, increased acetaldehyde and ethanol in unaged seeds to levels similar to those in accelerated-aged seeds after 2 hours imbibition. It is suggested that, during aging, an imbalance between tricarboxylic and glycolytic activities, present during early imbibition to some degree even in vigorous unaged seeds, becomes more pronounced and leads to accumulation of ethanol and acetaldehyde.

Abstract: The effects of varying concentrations of ethanol (1, 10, and 30 mM) and its metabolites (1 mM acetate and 1 and 10 mM acetaldehyde) on insulin and glucagon secretion induced by glucose (11.1 mM) and arginine (20 mM) were studied in isolated perfused pancreas of Sprague-Dawley rats. Ethanol and its metabolites did not significantly modify basal secretion of the two hormones. Ethanol reduced glucose-induced insulin secretion by means of a dose-related effect. Arginine-induced insulin output did not seem to be influenced to any significant degree. Acetate and acetaldehyde significantly inhibited glucose and arginine-induced insulin secretion. While ethanol (10 and 30 mM ) did not modify glucagon output during arginine perfusion, acetate and acetaldehyde markedly enhanced it. The block of insulin secretion and the increased secretion of glucagon could explain the diabetogenic effect of ethanol demonstrated in vivo. The mechanism by which ethanol acts on the pancreatic beta- and alpha-cells is discussed.

Abstract: 1 Ethanol was oxidized more slowly by rats which were given an ethanol dose of 5.1 g/kg than by rats which were given an ethanol dose of 1.4 g/kg. 2 A positive correlation was found between [lactate]/[pyruvate] ratios and rates of ethanol oxidation. 3 Acetaldehyde concentrations varied widely between rats, but in some cases were high enough to influence rates of ethanol oxidation. 4 Liver alcohol dehydrogenase levels were just sufficient to account for ethanol oxidation rates observed invivo 5 Pre-administration fo a large ethanol dose (6.5 g/kg) did not alter mean [lactate]/[pyruvate] ratios or ethanol oxidation rates during metabolism of test doses of 2.5 g/kg. 6 Injection of pyruvate did not increase rates of ethanol oxidation. 7 The results do not support suggestions that a high Km ethanol oxidizing system plays an important role in vivo, that increased rates of ethanol oxidation can be induced by large, acute ethanol doses or that he rate of NADH reoxidation controls rates of ethanol metabolism. 8 The results support other evidence which has indicated that the level of alcohol dehydrogenase is the major factor limiting rates of ethanol oxidationin vivo.

Abstract: Rate constants for the gas-phase reactions of O3 with the carbonyls acrolein, crotonaldehyde, methacrolein, methylvinylketone, 3-penten-2-one, 2-cyclohexen-1-one, acetaldehyde, and methylglyoxal have been determined at 296 ± 2 K. The rate constants ranged from <6 × 10−21 cm3 molecule−1 s−1 for acetaldehyde to 2.13 × 10−17 cm3 molecule−1 s−1 for 3-penten-2-one. The substituent effects of CHO and CH3CO groups on the rate constants are assessed and discussed, as are implications for the atmospheric chemistry of the natural hydrocarbon isoprene.

Abstract: A pseudoCushing syndrome, indistinguishable from true Cushing syndrome except that it disappears with abstinence from alcohol, is known to occur in alcoholics. An animal model was used to study this syndrome in vitro, as earlier studies have shown that ethanol administration to animals increases corticosterone secretion. Such secretion appears to be the result of ethanol-induced ACTH secretion. We have examined the effects of ethanol and acetaldehyde on the production of three steroids: corticosterone, progesterone, and androstenedione in the isolated perfused rat adrenal. The adrenal glands and left kidney of rats were perfused with medium and one of the following additions: ethanol, acetaldehyde, ACTH or ACTH with either ethanol or acetaldehyde. The amount of the three steroids in the adrenal and the perfusion effluent was determined and compared to that of nonperfused adrenal glands. We found that perfusion with medium alone increased the production of each steroid (p

Abstract: 4-methylpyrazole (4-MP), an inhibitor of alcohol dehydrogenase, rapidly abolished the accumulation of acetaldehyde following alcohol ingestion both in volunteers pretreated with the Antabuse analog calcium carbimide and in an antabuse-treated alcoholic. 4-MP also attenuated other typical symptoms, including facial flushing and tachycardia, thus suggesting its usefulness in the acute treatment of severe disulfiram-alcohol reactions.

Abstract: Calcium cyanamide, an aldehyde dehydrogenase (ALDH) inhibitor used in the treatment of alcoholism, strongly suppressed voluntary ethanol drinking by rats Such inhibitors have generally been believed to act primarily by limiting drinking through acetaldehyde accumulation after ethanol consumption Administration of a low dose of 4-methylpyrazole (4-MP) that abolished acetaldehyde accumulation did not, however, remove the suppression produced by cyanamide 4-MP alone did not affect the unsuppressed alcohol intake by Long Evans rats or the drinking by rats of the ANA strain developed for low levels of ethanol consumption When given from the start with cyanamide, 4-MP did affect the development of the suppression, but probably by its effect in lessening the degree of brain ALDH inhibition: a high correlation (r = +0825, p less than 0001) was found between brain ALDH activity and ethanol consumption The results suggest that cyanamide suppresses alcohol drinking also in the absence of acetaldehyde accumulation probably by some action related to its direct inhibition of brain ALDH

Abstract: The effect of ethanol, acetaldehyde, and acetate upon testicular production of testosterone was studied utilizing the isolated perfused rat testes. In addition, effects of 4-methylpyrazole (an inhibitor of alcohol dehydrogenase) and methylene blue (a proton acceptor) were evaluated alone and with addition of ethanol. Finally, the effect of penicillamine (a drug that forms a Schiff base with acetaldehyde) alone and with the addition of acetaldehyde to the perfusion medium was assessed. No changes in testicular light microscopic appearance and ATP content were noted as a result of the 2 h of perfusion. Testosterone production by the isolated perfused testes was reduced in a dose-related manner by the addition of ethanol over a range of concentrations from 50–150 mg/dl. Moreover, both acetaldehyde and acetate, products of ethanol and acetaldehyde metabolism, respectively, also inhibited testicular production of testosterone. In contrast, the addition of 4-methylpyrazole or methylene blue to the perfusion med...

Abstract: A commercial buttermilk culture was added to Grade a skim milk. Samples were analyzed hourly for a total of eighteen hours. Headspace gas chromatography measured changes in acetaldehyde, acetone, ethanol, and diacetyl concentrations. High performance liquid chromatography measured changes in orotic, citric, pyruvic, lactic, uric, acetic, and propionic acid concentrations. Consumption of orotic acid and citric acid substrates was noted. Production of diacetyl, ethanol, pyruvic, lactic, acetic, and propionic acids was observed. Acetaldehyde concentration increased initially and then decreased as ethanol was formed. Acetone and uric acid concentrations remained constant during fermentation. In addition, chemical changes occurring during refrigeration were measured after seven days. Acetaldehyde, ethanol, and acetic acid increased in concentration; diacetyl, orotic, citric, pyruvic, lactic, and propionic acids decreased in concentration. Also, a headspace gas chromatographic test was done for the quantitation of acetoin.

Abstract: The kinetic mechanism for the formation and decay of HCO(0,0,0) following flashlamp excitation (10 μs pulse width) into the 1A″ → 1A′ absorption transition of gas phase acetaldehyde (0.2 Torr) was examined by time-resolved intracavity laser detection (TRMD) and by phosphorescence lifetime measurements. The HCO radical was found to appear primarily in the vibrationless level reaching a maximum concentration about 250 μs after the excitation of acetaldehyde. The formation rate of HCO(0,0,0) was observed to be insensitive to an order of magnitude change in the number of collisions of excited-state acetaldehyde with either argon, cyclohexane, or the cell wall. Contrastingly, the decay rate of HCO exhibited a strong dependence on the collisional environment. The rate constants for HCO(0,0,0) decay by collisions with acetaldehyde, argon, and cyclohexane and by reaction with O2 were measured by TRILD. The rate constant for O2, quenching of 3A″ phosphorescence was also obtained. The potential for HCO(0,0,0) being either a primary or secondary dissociation product is considered in the formulation of a kinetic mechanism describing both the formation and decay behavior observed. Evidence is presented in support of a mechanism in which (1) HCO(0,0,0) is formed by the thermal reaction between acetyl radicals. CH3CO, and ground-state acetaldehyde after excited-state acetaldehyde undergoes primary dissociation to CH3CO, and (2) HCO(0,0,0) decays principally by collisionally-induced dissociation at the cell wall.

Abstract: To test the suggestion that chlorpropamide-alcohol flushing (CPAF) resembles the disulfiram effect and might be mediated by acetaldehyde, the initial metabolite of alcohol, blood concentrations of acetaldehyde were measured after a drink of alcohol in controls and diabetics positive and negative for CPAF. The CPAF-positive diabetics had significantly greater blood acetaldehyde concentrations after alcohol than the CPAF-negative diabetics both with a single dose of chlorpropamide and after two weeks' chlorpropamide treatment. Concentrations in the CPAF-positive group after chlorpropamide were also significantly greater than after a placebo tablet. There was also a clear separation in the increase in facial temperature after two weeks of chlorpropamide between the CPAF-positive and CPAF-negative groups (although there was some overlap after a single tablet). There was no difference in plasma chlorpropamide or alcohol concentrations between CPAF-positive and CPAF-negative diabetics. These findings show that CPAF is distinct from alcohol flushing and that the acetaldehyde concentration in the blood provides an objective measure of CPAF. The difference between flushing and non-flushing diabetics cannot be accounted for by differences in blood concentrations of chlorpropamide or alcohol.

Abstract: Ethanol is easily absorbed from the intestine and diffuses quickly throughout body water. The bulk of ethanol is metabolized in the liver, where alcohol dehydrogenase, a complex mixture of isoenzymes, oxidizes ethanol to acetaldehyde. Ethanol abuse produces functional and structural changes in the gastrointestinal tract, such as in the stomach, small intestine, liver, and pancreas. Accumulating evidence suggests direct toxicity of ethanol and possibly of acetaldehyde. Fatty liver, alcoholic hepatitis, liver cirrhosis, acute and chronic gastritis, deranged structure and function of the small intestine, acute and chronic pancreatitis, and pancreatic lithiasis are some of the sequelae of ethanol abuse. Recent investigations have enhanced our understanding of the functional and structural changes of the gastrointestinal tract produced by the abuse of ethanol.

Abstract: The effect of ethanol infusion upon placental uptake of amino acids was studied in pregnant sheep. Blood ethanol levels of 150-260 mg/dl obliterated the normal uptake of amino acids by the in vivo placenta. However, when human placental villi were incubated in vitro with ethanol at 300 mg/dl, there was no inhibition of uptake of 14C alpha-amino isobutyric acid (AIB). In contrast, 2-20 mM, but not 50 or 200 micro M, acetaldehyde significantly inhibited AIB uptake (% inhibition at 90 min: 2 mM, 23.5 +/- 9.6%; 5 mM, 33.8 +/- 4.7%; 10 mM, 54.6 +/- 2.9%; 20 mM, 61.5 +/- 7.5%; p less than 0.01 for all 4 concentrations). When human placental villi were preincubated with 10 micro M acetaldehyde, washed, and incubated with 14C-AIB in the absence of acetaldehyde, there was significant residual inhibition of AIB uptake. The data suggest that ethanol-associated placental injury may contribute to the pathophysiology of the fetal alcohol syndrome.

Abstract: Diamine oxidase (EC 1436) activity, measured as Δ1-[14C]pyrroline formation from [14C]putrescine, was studied in homogenates of regenerating liver and of 4-dimethylaminoazobenzene-induced and Yoshida AH 130 hepatomas of rat The addition in the incubation medium of acetaldehyde increased Δ1-pyrroline formation in normal and regenerating liver that contained aldehyde dehydrogenase but not in hepatomas where this enzymatic activity was very low or virtually absent Acetaldehyde did not modify the activity of a preparation of hog kidney diamine oxidase, while chloral hydrate and disulfiram, respectively, enhanced and depressed the activity of this enzyme These results suggest that aldehyde-metabolizing enzymes present in homogenate may interfere with the amount of Δ1-pyrroline formation and that the use of acetaldehyde may give better information on tissue diamine oxidase activity Diamine oxidase activity, which was very low in normal liver, increased rapidly in regenerating liver and reached maximum values between 16 and 48 hr after hepatectomy A large increase in diamine oxidase activity, as compared to the values of normal liver, was also observed in 4-dimethylaminoazobenzene and Yoshida ascites hepatomas