Synthesis of hepatotoxic agents in germfree and conventional mice which had been fed NaNO 2 and dimethylamine

Indian National Association for the Study of Liver Consensus Statement on Acute Liver Failure (Part-2): Management of Acute Liver Failure

Acute liver failure (ALF) is not an uncommon complication of a common disease such as acute hepatitis. Viral hepatitis followed by antituberculosis drug-induced hepatotoxicity are the commonest causes of ALF in India. Clinically, such patients present with appearance of jaundice, encephalopathy, and coagulopathy. Hepatic encephalopathy (HE) and cerebral edema are central and most important clinical event in the course of ALF, followed by superadded infections, and determine the outcome in these patients. The pathogenesis of encephalopathy and cerebral edema in ALF is unique and multifactorial. Ammonia plays a crucial role in the pathogenesis, and several therapies aim to correct this abnormality. The role of newer ammonia-lowering agents is still evolving. These patients are best managed at a tertiary care hospital with facility for liver transplantation (LT). Aggressive intensive medical management has been documented to salvage a substantial proportion of patients. In those with poor prognostic factors, LT is the only effective therapy that has been shown to improve survival. However, recognizing suitable patients with poor prognosis has remained a challenge. Close monitoring, early identification and treatment of complications, and couseling for transplant form the first-line approach to manage such patients. Recent research shows that use of dynamic prognostic models is better for selecting patients undergoing liver transplantation and timely transplant can save life of patients with ALF with poor prognostic factors.

Gut microbiota in liver disease: too much is harmful, nothing at all is not helpful either

The intestinal microbiome plays a major role in the pathogenesis of liver disease, with a hallmark event being dysbiosis, or an imbalance of pathobionts and beneficial bacteria with the associated deleterious effects on their host. Reducing the number of intestinal bacteria with antibiotic treatment is generally advantageous in experimental liver diseases. Complete absence of intestinal microbiota as in germ-free rodents can be protective in autoimmune hepatitis and hepatic tumors induced by chemicals, or it can exacerbate disease as in acute toxic liver injury and liver fibrosis/cirrhosis. In alcoholic liver disease, nonalcoholic fatty liver disease, and autoimmune cholangiopathies, germ-free status can be associated with worsened or improved hepatic phenotype depending on the experimental model and type of rodent. Some of the unexpected outcomes can be explained by the limitations of rodents raised in a germ-free environment including a deficient immune system and an altered metabolism of lipids, cholesterol, xenobiotics/toxins, and bile acids. Given these limitations and to advance understanding of the interactions between host and intestinal microbiota, simplified model systems such as humanized gnotobiotic mice, or gnotobiotic mice monoassociated with a single bacterial strain or colonized with a defined set of microbes, are unique and useful models for investigation of liver disease in a complex ecosystem.

Teratogenic and macromolecular synthesis inhibitory effects of trimethylamine on mouse embryos in culture

Trimethylamine (TMA) is an aliphatic amine, and its blood levels can increase after ingestion of certain foods, such as fish, and during disease states, such as chronic renal failure. We recently reported that TMA can inhibit fetal development in vivo and in vitro in mice. The present studies were done to find out if the inhibitory effects of TMA on embryonic development are caused by a decrease in macromolecular synthesis, using mouse embryo cultures as the experimental model. At a submaximally toxic concentration (0.75mM), TMA inhibited the growth of embryos to approximately 70% of control and caused neural-tube defects in 73% of embryos. By 42 h of culture, DNA, RNA, and protein content of TMA-treated embryos were approximately 50% of the control values. Embryotoxic effects of TMA were not caused by changes in pH and osmolarity of the culture media. The inhibitory effects of TMA on embryonic growth were time dependent and apparent at 2-4 h of culture. The inhibition of growth was accompanied by a decrease in the incorporation of tritium-labeled thymidine, uridine, and leucine into DNA, RNA, and proteins, respectively. Thiols (L- and D-cysteine, glutathione) and the antioxidant L-ascorbic acid did not cause significant antagonism of embryotoxic effects of TMA. It is concluded that TMA exerts teratogenic effects on mouse embryos in culture and inhibits their growth by reducing macromolecular synthesis; these effects may not involve glutathione depletion or generation of free radicals.