Tissue inhibitor of metalloproteinase is increased in the serum of precirrhotic and cirrhotic alcoholic patients and can serve as a marker of fibrosis.

One of the contributory factors to the development of cirrhosis is a decrease in collagenase activity, which may be related to levels of inhibitors such as serum tissue inhibitor of metalloproteinase. We therefore measured serum tissue inhibitor of metalloproteinase and serum procollagen III peptides (another proposed marker of fibrosis) in 16 healthy controls and 44 alcoholic patients with biopsy-proved liver disease, namely steatosis without fibrosis (n = 13), perivenular fibrosis (n = 10), septal fibrosis or cirrhosis or both (n = 15) and alcoholic hepatitis (n = 6). In alcoholic patients, serum tissue inhibitor of metalloproteinase values strongly correlated with fibrosis (rs = 0.

Susceptibility to alcohol-related liver injury.

Alcohol affects the liver through metabolic disturbances associated with its oxidation. Redox changes produced by the hepatic alcohol dehydrogenase pathway affect lipid, carbohydrate and protein metabolism. Ethanol is also oxidized in liver microsomes by the ethanol-inducible cytochrome P4502E1, resulting in ethanol tolerance and selective hepatic perivenular damage.

First pass metabolism of ethanol.

The human stomach has both low and high K(m) ADH isozymes, resulting in significant ethanol metabolism in gastric cells in vitro, and decreased bioavailability of ethanol (first pass metabolism: FPM) in vivo. Intraduodenal or intraportal infusion of amounts of ethanol equivalent to those emptied into the duodenum or disappearing from pylorus-ligated stomachs produced significantly higher blood levels than intragastric administration, whereas portal ligation had no effect, documenting the role of gastric ethanol metabolism in vivo. This "protective barrier" against the systemic effects of ethanol disappears after gastrectomy and is partly lost in the alcoholic because of accelerated gastric emptying and decreased gastric ADH activity, respectively.

Mechanisms of ethanol-drug-nutrition interactions.

Mechanisms of the toxicologic manifestations of ethanol abuse are reviewed. Hepatotoxicity of ethanol results from alcohol dehydrogenase-mediated excessive hepatic generation of nicotinamide adenine dinucleotide and acetaldehyde. It is now recognized that acetaldehyde is also produced by an accessory (but inducible) pathway, the microsomal ethanol-oxidizing system, which involves a specific cytochrome P450.

First-pass metabolism of ethanol is predominantly gastric.

Oral consumption of alcohol results in much lower blood alcohol concentrations (BACs) than does the same dose administered intravenously, suggesting significant first-pass metabolism (FPM). The questions remain, however, (1) whether this difference truly represents FPM or simply reflects slower absorption of alcohol, and (2) if there is FPM, is it mainly of gastric or hepatic origin. To study this, rats were given the same dose alcohol (1 g/kg) by either intragastric intubation or by intravenous, intraportal, and intraduodenal infusions at a rate that mimicked the loss of alcohol from the stomach.

Alcohol consumption enhances fatty acid omega-oxidation, with a greater increase in male than in female rats.

Because ethanol inhibits mitochondrial fatty acid oxidation, with substantial accumulation of fatty acids in the livers of female (but not male) rats, and induces microsomal activities, we assessed possible changes in omega-oxidation. To study this, we pair-fed 24 male and 24 female littermate rats of the same age liquid diets containing 36% of energy either as ethanol or as additional carbohydrate for 4 wk. In controls, the microsomal omega-hydroxylation of lauric acid was 28% greater in female than in male rats (p < 0.

Ethanol metabolism in deermice: role of extrahepatic alcohol dehydrogenase.

The relative contributions to ethanol metabolism of extrahepatic alcohol dehydrogenase (ADH) and of liver microsomes were assessed in deermice, which lack hepatic low Km ADH (ADH-). In vitro kinetic studies showed the existence of high Km (> 1 M) ADH activity in the liver and kidney, and an enzyme with intermediate Km in the gastric mucosa (Km = 133 mM), whereas the low Km ADH was missing. With deuterated ethanol, ADH- deermice showed a significant exchange of reducing equivalents that had been equated with ethanol metabolism by others, whereas we found a poor correlation between the rate of exchange and the rate of metabolism.

Acetaldehyde adducts and autoantibodies against VLDL and LDL in alcoholics.

Alcohol consumption markedly increases the hepatic output of very low density lipoprotein (VLDL), whereas it decreases the resulting low density lipoprotein (LDL) levels and apolipoprotein B. As ethylation of apoB-lysine renders LDL immunogenic and accelerates their clearance, and as alcoholics develop antibodies against acetaldehyde-protein adducts, we searched for antibodies against lipoproteins. We measured serum IgG, IgA, and IgM titers against VLDL, LDL and high density lipoprotein (HDL) in 10 non-alcoholics and 35 recently drinking alcoholics by ELISA assay.

Effects of ethanol on prostanoid production by liver fat-storing cells.

Fat-storing cells participate in the development of alcoholic liver disease. To study possible effects of ethanol on prostaglandin metabolism by fat-storing cells, we isolated them from normal rat liver. Cultured fat-storing cells produced substantial amounts (DNA, about 2 ng/micrograms every 24 hr) of prostaglandin E2 and prostaglandin I2 (measured as 6-keto prostaglandin F1 alpha) but no significant amounts of prostaglandin F2 alpha.

In vivo induction of hepatic P4502E1 by ethanol: role of increased enzyme synthesis.

P4502E1 (2E1), an ethanol-inducible P450 enzyme, plays an important role in the bioactivation of certain hepatotoxins and chemical carcinogens. Different mechanisms of 2E1 induction by ethanol and other agents (e.g.

Hepatitis C virus antibody in alcoholic patients. Association with the presence of portal and/or lobular hepatitis.

Objective: To evaluate the relationship between hepatitis C viral infection and alcoholic liver disease.

Design: Case-comparison study.

Setting: Bronx (NY) Veterans Affairs Medical Center.

Induction of cytochrome P-4502E1 in the human liver by ethanol is caused by a corresponding increase in encoding messenger RNA.

The propensity of centrilobular liver damage to develop in alcohol abusers after exposure to various hepatotoxins, including ethanol itself, has been linked to the induction by ethanol of P-4502E1, a microsomal P-450 enzyme that bioactivates these agents to reactive metabolites. Whereas long-term ethanol consumption elicits a marked increase in hepatic P-4502E1 content, the molecular mechanism by which ethanol produces this effect is the subject of controversy in animals, and it has not been elucidated in human beings. Possible mechanisms include increased enzyme synthesis stemming from elevated 2E1 messenger RNA levels, enhanced translation of preexisting messenger RNA or stabilization of P-4502E1 protein.

Acetaldehyde-collagen adducts in N-nitrosodimethylamine-induced liver cirrhosis in rats.

Increased acetaldehyde levels have been found in non-alcoholic liver diseases and an acetaldehyde-collagen adduct has been reported in rats with CCl4-induced cirrhosis. In cytosol and microsomes of rats with cirrhosis produced by N-nitrosodimethylamine, a similar acetaldehyde-protein adduct of approximately 200 kD was recognized by rabbit IgG raised against either an in vitro produced hemocyanin-acetaldehyde adduct or an in vivo occurring P4502E1-acetaldehyde adduct isolated from alcohol-fed rats, as well as by anti-rat collagen (I) IgG. Its immune complexes contained 3 proteins that reacted with the anti-collagen IgG and were digested by collagenase: 2 proteins with molecular weights similar to procollagens alpha 1 and alpha 2, and a beta 1,2(I)-like protein which was readily produced by in vitro modification of cytosol with acetaldehyde.

Comparison of new methods for measuring carbohydrate-deficient transferrin (CDT): application to a public health approach for the prevention of alcoholic cirrhosis.

Recently, Xin et al. (1991) developed an isoelectric focusing/Western blot (IEF/WB) procedure for serum CDT measurement which compares favorably with the micro anion-exchange chromatography/radioimmunoassay technique of Stibler et al. (1986).

Uridine diphosphoglucose restores lipocyte proliferation in the regenerating liver of ethanol-treated rats.

The effect of continuous intraperitoneal infusion of uridine diphosphoglucose on ethanol-induced suppression of lipocyte proliferation was studied in regenerating rat livers from 1-4 days after hepatectomy. Proliferating lipocytes were positively identified using a two-sequence immunohistochemical staining for cytoplasmic desmin and bromodeoxyuridine-labelled nuclei. Hepatectomy rapidly stimulated lipocyte proliferation which peaked 2 days after hepatectomy (labelling index, 17.

Polyunsaturated lecithin prevents acetaldehyde-mediated hepatic collagen accumulation by stimulating collagenase activity in cultured lipocytes.

We recently found that polyunsaturated lecithin prevents ethanol from causing cirrhosis in the baboon. Because transformation of lipocytes to transitional cells plays a key role in hepatic fibrogenesis in vivo, and because this process in alcohol-fed baboons was found to be attenuated by polyunsaturated lecithin, we focused on lipocytes to study the mechanism of the protective effect. Rat lipocytes cultured on plastic undergo spontaneous activation, accompanied by expression of alpha-smooth muscle actin isoform and production of substantial amounts of type I collagen.

Effects of H2-receptor antagonists on gastric alcohol dehydrogenase activity.

Inhibition of gastric alcohol dehydrogenase (ADH) activity by cimetidine results in elevated blood levels of ethanol after moderate consumption. To search for alternative H2-blockers lacking such an effect, we compared cimetidine, ranitidine, nizatidine, and famotidine. They inhibited rat gastric ADH noncompetitively, with a Ki for ethanol oxidation of 0.

Isoelectric focusing/western blotting: a novel and practical method for quantitation of carbohydrate-deficient transferrin in alcoholics.

Carbohydrate-deficient transferrin (CDT) has been described as the single, most accurate marker of chronic alcohol consumption. Rapid, sensitive, and specific measurement of serum CDT levels can thus provide important clinical information concerning patient diagnosis and treatment. To date, however, methods used for assessing CDT concentrations [e.

Effect of concentration of ingested ethanol on blood alcohol levels.

The effect of the concentration of ingested ethanol on the resulting blood alcohol concentrations (BAC) was tested in both humans and rats. In humans, when 0.3 g/kg body weight ethanol was ingested postprandially, the mean area under the blood alcohol curve (AUC) and the mean peak BAC were significantly lower with a concentrated (40% w/v) than with a dilute (4%) solution.

Hepatic, metabolic and toxic effects of ethanol: 1991 update.

Until two decades ago, dietary deficiencies were considered to be the only reason for alcoholics to develop liver disease. As the overall nutrition of the population improved, more emphasis was placed on secondary malnutrition and direct hepatotoxic effects of ethanol were established. Ethanol is hepatotoxic through redox changes produced by the NADH generated in its oxidation via the alcohol dehydrogenase pathway, which in turn affects the metabolism of lipids, carbohydrates, proteins, and purines.

Acetaldehyde increases procollagen type I and fibronectin gene transcription in cultured rat fat-storing cells through a protein synthesis-dependent mechanism.

We previously reported that acetaldehyde increases the production of type I collagen in cultured rat fat-storing cells. We studied the regulation of this effect by determining the expression of procollagen type I, fibronectin and transforming growth factor-beta 1 messenger RNAs in passage 1 and 2 cultures of fat-storing cells exposed to acetaldehyde for up to 24 hr. By 6 hr, acetaldehyde increased the steady-state levels of alpha 1 procollagen type I messenger RNA 3.

The effect of the prostaglandin analogue-misoprostol on rat liver mitochondria after chronic alcohol feeding.

Rats fed ethanol (36% of total calories in a nutritionally adequate liquid diet) for 5 weeks develop functional alterations of hepatic mitochondria and steatosis of the liver. At the fatty liver stage, ADP-stimulated respiration of mitochondria was depressed in ethanol fed rats by 30% (p less than 0.001) with glutamate + malate and by 23% (p less than 0.

Alcohol and fibrogenesis.

In addition to fibrosis in response to necrosis and inflammation, alcohol may promote fibrogenesis directly, resulting in pericellular, perisinusoidal and perivenular fibrosis, in association with increased collagen mRNA. Acetaldehyde (produced in increased amounts because of the selective induction of cytochrome P450IIE1) stimulates collagen formation from either myofibroblasts, Ito cells or fibroblasts. One postulated mechanism is adduct formation of acetaldehyde with intracellular proteins, possibly stabilized by the NADH generated upon ethanol oxidation.

Effects of liver disease on red blood cell acetaldehyde in alcoholics and non-alcoholics.

High endogenous levels of acetaldehyde were found in the blood (mainly in red blood cells) of patients with liver disease of various etiologies. The presence of severe liver injury increased the blood acetaldehyde response to ethanol consumption and resulted in a more prolonged persistence of high levels after ethanol withdrawal.