Ethanol metabolism in the generation of new antigenic determinants on liver cells.

Antibodies directed against ethanol altered liver cell components have been detected in the serum of nearly 50% of patients with alcoholic liver disease although the pathogenetic mechanisms are unclear. The importance of ethanol metabolism in the generation of new antigenic determinants on liver cells was investigated by in vivo inhibition of alcohol or acetaldehyde dehydrogenase and an induced cytotoxicity assay. There was a significant reduction in cytotoxicity to hepatocytes isolated from rabbits treated with ethanol 1 g/kg when the metabolism of ethanol to acetaldehyde by alcohol dehydrogenase was inhibited. In contrast when the oxidation of acetaldehyde was inhibited by disulfiram cytotoxicity was significantly enhanced. These results show that ethanol metabolism is integral to the expression of the ethanol related determinant and suggest that an impaired ability to metabolism acetaldehyde could lead to the development of immunological reactions to alcohol altered liver membrane antigens.

Effects of ethanol administration on rat liver plasma membrane-bound enzymes.

Changes in the properties of rat liver plasma membranes were examined in studies designed to differentiate between direct and metabolic effects of acute and chronic ethanol ingestion. One hour after a single dose of ethanol (3 g/kg body weight) there were increases in Na+,K+-ATPase (32%) and 5'-nucleotidase (36%), and hepatic concentrations of ethanol and acetaldehyde were approximately 23 mM and 50 microM, respectively. Na+,K+-ATPase and 5'-nucleotidase activities in liver plasma membranes from control rats were not significantly changed by in vitro addition of 30 microM acetaldehyde or 50 mM ethanol. Increases in Na+,K+-ATPase (approximately 20%) and 5'-nucleotidase (approximately 30%) were also observed in liver plasma membranes isolated from rats 16 hr after feeding ethanol or sucrose supplements for 17 days. The intake of calories from dietary protein and lipid was decreased by about 25% in both the ethanol and sucrose-fed animals. Na+,K+-ATPase activities in liver plasma membranes isolated from control rats were inhibited (approximately 20%) by 100 mM ethanol in vitro, whereas no inhibition was observed using membrane preparations from rats fed ethanol or sucrose supplements. Our results show that changes in liver plasma membrane enzyme activities associated with a single dose of ethanol are not a direct effect correlated with blood, hepatic or plasma membrane concentrations of ethanol or acetaldehyde. Chronic ingestion of ethanol or sucrose supplements had similar effects on liver plasma membrane enzyme characteristics and parallel changes in nutrient intake may be a more feasible explanation of these results than any analogous direct effects of the two compounds.

Effects of converting enzyme inhibitor on hepatic blood flow in man.

The acute effects of the oral angiotension converting enzyme inhibitor captopril on hepatic blood flow and systemic hemodynamics were studied in six patients with essential hypertension. Mean arterial pressure decreased from 141.9 +/- 6.9 mm Hg to 130.2 +/- 6.7 mm Hg (p less than 0.05) one hour after the administration of captopril. There was no significant change in other hemodynamic values, but hepatic blood flow decreased uniformly from 1,127 +/- 115 ml per minute to 841 +/- 93 ml per minute (p less than 0.001).

Antibodies to alcohol altered liver cell determinants in patients with alcoholic liver disease.

Circulating antibodies reacting specifically with hepatocytes isolated from ethanol pretreated rabbits have been demonstrated by two techniques - induced cytotoxicity and immunofluorescence. In the cytotoxicity assay antibodies were found in seven of 19 (39%) of patients with alcoholic fatty liver (with or without fibrosis), six of 13 (46%) of those with alcoholic hepatitis, 15 of 36 (43%) of those with cirrhosis, and seven of 14 patients (50%) of those with hepatitis and cirrhosis. In the immunofluorescence studies, nine of 15 sera induced a granular pattern of fluorescence on the ethanol pretreated hepatocytes; two sera which induced significant cytotoxicity did not induce immunofluorescence. No ethanol related antibodies were found in normal individuals or in patients with other types of acute or chronic liver disease. These results show that antibodies directed against ethanol altered liver cell determinants are present in the serum of 43% of patients with alcoholic liver disease, and suggest a mechanism whereby chronic alcohol consumption may, by inducing antigenic changes in hepatocyte membranes, trigger a cell damaging immune reaction.

Selective and non-selective beta receptor blockade in the reduction of portal pressure in patients with cirrhosis and portal hypertension.

To elucidate the mechanisms by which beta receptor blockade leads to a reduction of portal pressure, 18 patients with cirrhosis and portal hypertension were given comparable doses of propranolol or metoprolol. The fall in portal pressure was more marked with propranolol together with a significant reduction in hepatic blood flow, which was not seen with metoprolol. No correlation between the reduction in cardiac output and the decrease in portal pressure or changes in hepatic blood flow could be elicited in each group, but there was a direct relationship between the decrease in hepatic blood flow and fall in portal pressure in the propranolol treated patients. The difference observed may be related to blockade of beta 2 vasodilator receptors in the splanchnic circulation which will occur only with propranolol and lead to a greater fall in splanchnic blood flow than will be produced by a reduction in cardiac output alone. Metoprolol, by maintaining effective hepatic blood flow, may be preferable to propranolol in patients with severely impaired liver function.

Effect of chronic alcohol intake on hepatic fibrosis and granulomas in murine schistosomiasis mansoni.

In consideration of the vast prevalence of schistosomiasis and heavy alcohol consumption in many parts of the world, the possibility of an interaction between these two conditions inducing liver disease was studied in mice infected with Schistosoma mansoni. Alcohol consumption significantly reduced by 25% the mean granuloma diameter and by about 60% the extent of fibrous tissue deposition determined chemically as hydroxyproline. DNA, as an expression of the inflammatory and cellular components of the granulomatous reaction in the infected animals, was also significantly reduced by alcohol consumption. These results indicate the need for epidemiological studies in the clinical manifestations and course of schistosomiasis in human alcoholics.

Correlation of intrahepatic pressure with collagen in the Disse space and hepatomegaly in humans and in the rat.

In 70 alcoholic patients the amount of collagen in the space of Disse was compared, using an electron microscopic graded score, to the height of the intrahepatic pressure. A highly significant correlation was found between the amount of collagen and intrahepatic pressure in the group as a whole (r = 0.84; p < 10(-6)), as well as in subgroups of 30 alcoholic patients with normal livers or steatosis (r = 0.83; p < 10(-6)), 9 patients with alcoholic hepatitis (r = 0.81; p < 0.01), and 31 with cirrhosis (r = 0.86; p < 10(-6)). A nonparametric correlational analysis for the complete group also showed a significant relationship (rho = 0.85; p < 10(-6)) between collagen scores and intrahepatic pressure. In 60 patients hepatocyte surface area was measured in the biopsies. In these, hepatocyte surface area significantly correlated with intrahepatic pressure (r = 0.68; p < 10(-7)). No correlation was found between intrahepatic pressure and fat, alcoholic hyalin, or terminal hepatic vein sclerosis. Only with necrosis (r = 0.38; p < 0.001) and inflammation (r = 0.29; p < 0.05) was there a significant relationship with intrahepatic pressure. Chronic ethanol administration for 4 wk in liquid diets to young Wistar rats produced a 50% hepatomegaly due to an increase in hepatocyte size. Intrahepatic pressure in the rats receiving alcohol (19.3 +/- 2.3 mmHg) was significantly higher than in the controls on sucrose (10.4 +/- 0.9 mmHg) (p < 0.01). A highly significant correlation was found between hepatocyte surface area and intrahepatic pressure (r = 0.70; p < 0.005). There was no increase in collagen in the Disse space in these animals. Therefore, hepatomegaly in the absence of an increase in collagen in the Disse space may result in increased intrahepatic pressure. These studies may indicate a sequence of events: hepatomegaly, portal hypertension, and collagenization in the Disse space, which could occur in alcoholic liver disease.

Long-term ethanol administration and short- and long-term liver regeneration after partial hepatectomy.

The purpose of this study was to determine whether long-term ethanol consumption affects the long-term regeneration of the liver after partial hepatectomy and to study whether the metabolic demands imposed on the liver by the regenerative process accentuate liver damage produced in the liver by ethanol. Animals fed alcohol (35% of total calories) in liquid diets over time were partially hepatectomized (68% removal) and then were given ethanol-containing diets until complete liver restitution. They were studied at 24 hr and at 7 and 14 days. At these times, prior and continued ethanol administration did not result in changes in total DNA restituted, percent of cells undergoing mitosis, or incorporation of 3H-thymidine into DNA as determined chemically and by autoradiography. After partial hepatectomy, ethanol-fed animals showed a reduction in both DNA and proteins per gram of liver. However, these effects were the result of the hepatomegaly induced by ethanol and were also observed in sham-operated animals fed the diets containing ethanol. An apparent decrease in percent restitution of live weight was observed at 24 hr after hepatectomy in the ethanol-fed animals. However, this was caused by a marked increase in hepatocyte size in the controls, which matched the already enlarged hepatocytes in the ethanol-fed animals. Partial hepatectomy was found to transiently increase the lipid content of the livers in control animals. In ethanol-fed animals partial hepatectomy resulted in markedly fatty livers, as observed both histologically and chemically, which exceeded these abnormalities in alcohol-fed sham-operated rats. In conclusion, long-term ethanol consumption prior to partial hepatectomy and continuous ethanol consumption after the operation did not affect negatively the complete restitution of the liver when compared with controls.

Portal hypertension in vinyl-chloride production workers.

Portal hypertension was seen in seven patients who had been involved in the production of vinyl-chloride monomer for 4-15 years. Four presented with bleeding oesophageal varices. In liver biopsy specimens non-cirrhotic portal fibrosis was inconspicuous and was seen more clearly on wedge rather than needle biopsy specimens. The intrahepatic venous pattern was hardly distrubed. Three patients have done well following shunt surgery. In one patient an angiosarcoma developed, but fibrosis was a more common lesion and was probably not pre-malignant.

Monitoring liver disorders in vinyl chloride monomer workers using greyscale ultrasonography.

Recognition that vinyl chloride could be hepatotoxic led to a survey of workers to determine whether changes had been induced by past exposure, and to evaluate standard liver function tests as monitors of early liver abnormalities. Standard liver function tests were found to be unsuitable for the detection of such abnormalities in the population at risk. Of 487 workers examined, 102 (20-9%) had abnormalities on initial testing but only two were finally shown to have portal hypertension; in both cases, thrombocytopaenia provided the first diagnostic evidence since liver function tests were normal. Furthermore, 40 (35-7%) of 112 control subjects had initial test abnormalities. A sample of 19 workers with various exposures to vinyl chloride monomer were examined blind by greyscale ultrasonography. Five with minimal or no exposure were confirmed as normal but 12 of the remainder had abnormalities. These consisted of an enlarged portal vein (seven instances), splenomegaly (eight), and changes in hepatic texture (seven). Five of these 12 cases had previously been considered normal. It was concluded that greyscale ultrasonography had many advantages over standard methods for screening workers exposed to hepatotoxic chemicals, and should be the subject of a large scale evaluation.