Hepatic Encephalopathy, Hyperammonemia, and Ammonia Toxicity

This volume contains the papers presented at the International Symposium on "Cirrhosis, Hyperammonemia and Hepatic Encephalopathy", held in Valencia, Spain, January 24th-27th, 1994. Liver cirrhosis and other hepatic dysfunctions such as fulminant hepatic failure and congenital defects of urea cycle enzymes can lead to hepatic encephalopathy, coma and death. Hepatic encephalopathy is one of the main causes of death in western countries. The ability to detoxify ammonia by its incorporation into urea is diminished by impaired liver function, resulting in increased ammonia levels in blood and brain. Hyperammonemia is considered one of the main factors in the mediation of hepatic encephalopathy and the classical clinical treatments are directed towards reducing blood ammonia levels. However, the molecular bases of the pathogenesis of hepatic encephalopathy and the role of hyperammonemia in this process remain unclear and several hypotheses have been proposed. To clarify the mechanisms involved in hepatic encephalopathy and hyperammonemia suitable animal models are necessary. The animal models available and the ideal features of an animal model are presented in the initial part of the book.

Inhalt
Animal Models of Hepatic Encephalopathy and Hyperammonemia.- Brain Metabolism in Encephalopathy Caused by Hyperammonemia.- In Vivo Brain Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) in Hepatic Encephalopathy.- Role of the Cellular Hydration State for Cellular Function: Physiological and Pathophysiological Aspects.- Astrocyte-Neuron Interactions in Hyperammonemia and Hepatic Encephalopathy.- Spinal Seizures in Ammonia Intoxication.- Molecular Mechanism of Acute Ammonia Toxicity and of its Prevention by L-Carnitine.- Portal-Systemic Encephalopathy: a Disorder of Multiple Neurotransmitter Systems.- The GABA Hypothesis: State of the Art.- Neuropharmacologic Modulation of Hepatic Encephalopathy: Experimental and Clinical Data.- S-Adenosyl-L-Methionine Synthetase and Methionine Metabolism Deficiencies in Cirrhosis.- Diagnosis and Therapy of Hepatic Encephalopathy.- Neomycin Reduces the Intestinal Production of Ammonia from Glutamine.- N-Acetylglutamate Synthetase (NAGS) Deficiency.- Ornithine Transcarbamylase Deficiency: A Model for Gene Therapy.- Retroviral Gene Transfer for LDL Receptor Deficiency into Primary Hepatocytes.- The Carnitine System: Recent Aspects.- Use of Hepatocyte Cultures for Liver Support Bioreactors.- Hepatitis C Viral infection after Orthotopic Liver Transplantation.- Exercise-Induced Hyperammonemia: Skeletal Muscle Ammonia Metabolism and the Peripheral and Central Effects.- Possible Role of Ammonia in the Brain in Dementia of Alzheimer Type.- Contributors.