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Biomedical subjects

L Zieve

Publications and source records attributed to L Zieve.

97 records · Page 6Linked to original sources
PubMedDate not supplied

Visual evoked potentials in encephalopathy induced by galactosamine, ammonia, dimethyldisulfide, and octanoic acid.

Visual evoked potentials were utilized to examine the neuronal transmission changes provoked by galactosamine-induced hepatic encephalopathy and by administration in normal animals of toxins presumably involved in the pathogenesis of hepatic encepalopathy. Separate acute administrations of ammonia, dimethyldisulfide, and octanoic acid induced lethargy, convulsions in the case of the first two, and coma with visual-evoked potential patterns that never resembled the evoked potentials recorded in hepatic coma. By contrast, single and repeated administrations of the three above-mentioned toxins together at lower doses induced lethargy and coma with visual-evoked potential patterns similar to those observed in galactosamine-induced hepatic coma. These observations, together with previously published data, are consistent with the concept that the synergistic interaction of these toxins plays a significant role in the pathogenesis of hepatic encephalopathy.

Ammonia↗
PubMedDate not supplied

Ammonia, octanoate and a mercaptan depress regeneration of normal rat liver after partial hepatectomy.

Four injections of subcoma doses of ammonium acetate, octanoic acid or dimethyl disulfide during the first 24 hr after two-lobe hepatectomy in normal rats markedly depressed DNA synthesis as reflected by liver thymidine kinase activity or the incorporation of tritiated thymidine into hepatic DNA. Recovery from the depressant effects of the three toxins took 16 to 28 hr. Similar doses of the same toxins injected hourly for 3 or 5 hr after the two-lobe hepatectomy had similar depressant effects on the early peak of ornithine decarboxylase activity measured at 4 or 6 hr. Recovery occurred within 3 hr perhaps because of the very short half-life of ornithine decarboxylase and its rapid regeneration time. These observations may have implications for the lack of regeneration observed in many patients with fulminant hepatic failure who have accumulated sufficient ammonia, methanethiol and fatty acids over periods of days or weeks to become encephalopathic.

Ammonia↗
PubMedDate not supplied

In vivo studies of GABAergic effects in experimental hepatic encephalopathy.

The GABAergic agonist, muscimol, and antagonists, picrotoxin and bicuculline, have been studied in rats with chronic portacaval shunts and in rats developing hepatic encephalopathy after massive ischemic necrosis due to hepatic artery ligation within 48 hr of a portacaval shunt. After the chronic portacaval shunt and to a lesser extent in normal rats intraventricular muscimol resulted in chewing and eating behavior, ataxia and loss of balance that lasted 2 to 3 hr. Lethargy, stupor and coma did not occur. Intraventricular saline had no effect. Bicuculline i.p. lessened the effects of the muscimol. In rats developing hepatic encephalopathy, intraventricular muscimol shortened the time to precoma and coma by approximately 40%. Bicuculline i.p. counteracted this effect of muscimol significantly. However, neither bicuculline nor picrotoxin given alone altered the times to precoma (Stage III), coma (Stage IV) or death. While hepatic encephalopathy in this experimental model is susceptible to GABAergic effects, its natural progression does not appear to be due to GABA.

Animals↗
PubMedDate not supplied

Hepatic encephalopathy and orotic aciduria associated with hepatocellular carcinoma in a noncirrhotic liver.

A 40-yr-old man presented with encephalopathy and was found to have hepatocellular carcinoma without cirrhosis. A large vascular hepatic mass was defined by CT scan and angiography; laparoscopy with biopsy confirmed the absence of chronic liver disease. A definitive tissue diagnosis of hepatocellular carcinoma was made at laparotomy; the tumor was unresectable. Peripheral arterial and selective portal and hepatic venous ammonia levels were high, and this finding suggested that the encephalopathy was nitrogenous and hepatic in origin. The proposed mechanisms of the encephalopathy are generation of ammonia from tumor breakdown and portosystemic shunting, a result of partial tumor occlusion of the hepatic veins. An unusually high urinary excretion of orotic acid was found similar to that seen in hereditary orotic aciduria.

Adult↗