Alteration in cerebral polynucleotide metabolism following chronic ethanol ingestion

Alcoholic liver disease: pathologic, pathogenetic and clinical aspects

Alcoholic liver disease includes steatosis, alcoholic hepatitis and cirrhosis. Other liver diseases of genetic origin, but with a curious association with alcohol intake, are hemochromatosis and porphyria cutanea tarda. The attribution of chronic hepatitis to alcohol intake remains speculative, and the association may reflect hepatitis C infection. Hepatic injury attributed to alcohol includes the changes reported in the fetal alcohol syndrome. Steatosis, the characteristic consequence of excess alcohol intake, is usually macrovesicular and rarely microvesicular. Acute intrahepatic cholestasis, which in rare instances accompanies steatosis, must be distinguished from other causes of intrahepatic cholestasis (e.g., drug-induced) and from mechanical obstruction of the intrahepatic bile ducts (e.g., pancreatitis, choledocholithiasis) before being accepted. Alcoholic hepatitis (steatonecrosis) is characterized by a constellation of lesions: steatosis, Mallory bodies (with or without a neutrophilic inflammatory response), megamitochondria, occlusive lesions of terminal hepatic venules, and a lattice-like pattern of pericellular fibrosis. All these lesions mainly affect zone 3 of the hepatic acinus. Other changes, observed at the ultrastructural level, are of importance in progression of the disease. They include widespread cytoplasmic shedding, and capillarization and defenestration of sinusoids. Progressive fibrosis complicating alcoholic hepatitis eventually leads to cirrhosis that is typically micronodular but can evolve to a mixed or macronodular pattern. Hepatocellular carcinoma occurs in 5 to 15% of patients with alcoholic liver disease. The clinical syndrome of alcoholic liver disease is the result of three factors--parenchymal insufficiency, portal hypertension and the clinical consequences of extrahepatic damage produced by alcohol. At the several phases of the life history of alcoholic liver disease, the individual factors play a different role. The clinical manifestations of alcoholic steatosis are mainly extrahepatic in origin. Those of alcoholic hepatitis reflect mainly parenchymal insufficiency and those of cirrhosis are mainly those of portal hypertension. Alcoholic liver injury appears to be generated by the effects of ethanol metabolism and the toxic effects of acetaldehyde, perhaps the immune responses to alcohol- or acetaldehyde-altered proteins, and questionably enhanced by viral hepatitis. Alcoholic hepatitis may be mimicked histologically, and to a varying degree clinically, by a number of conditions (obesity, diabetes, several drug-induced injuries, jejunoileal bypass, and related "shortcircuiting" of the bowel). Perhaps the most important facet of the hepatotoxicity of alcohol is its enhancement of the effects of a number of other hepatotoxic agents, among which acetaminophen is the prime example.

Properties of cerebral polyribosomes and membranes of the rough endoplasmic reticulum after ethanol dependence in rats

Effects of physical dependence upon ethanol on the polyribosomal properties and the reconstitution of the rough endoplasmic reticulum (RER) of the brain has been examined. The purified free polyribosomes (polysomes), membrane-bound polysomes, and a fraction of RER membrane that has been stripped of polysomes were isolated from rat brain. RNA yields, amino acid incorporation activities, and electron micrographs established the purity of stripped membranes, but no differences were detected following the ethanol treatment. For the polyribosomal fractions, the stability of the mRNA/ribosomal complex was decreased after ethanol dependence as was the in vitro translation of endogenous mRNA. In the reconstitution reaction, the incubation of membranes from ethanol-treated animals with either source of purified bound polysomes resulted in higher yields of protein than when control membranes were used. The above results suggest that ethanol dependence affects the properties of both the RNA and membrane components of the RER of brain.

On the possibility that opiate and ethanol actions are mediated by similar mechanisms

Opiates and alcohol modify neuronal electrical activity in many sites of the nervous system. Both act as depressants or stimulants of cell firing depending upon the type of cell studied. Alcohol seems to act upon some nerves by changing their membrane ionic conductance, while opiates seem to affect synaptic events. However, all of the known neural actions of these substances involve calcium-dependent mechanisms. A hypothesis is proposed to account for these facts.