83 This study provided further support for the ammonia-glutamine brain water hypothesis see more of HE. The effect of hyperammonemia is likely to be determined by the ability of the astrocytes to maintain osmotic equilibrium by losing osmolytes such as myo-inositol in response to the ammonia-induced increase in glutamine.84 It has been observed that severity of MHE may not correlate with severity of liver disease or the level of ammonia, suggesting presence of other pathogenic influences. Inflammation is one such factor that may contribute to the development of MHE and its progression to overt HE.85 A recent study found that severity of MHE was independent

of severity of liver disease and levels of blood ammonia but markers of inflammation were significantly higher in those with MHE compared to those without MHE.86 Induction of hyperammonemia led to deterioration BMN 673 cell line in one

or more neuropsychological tests in 73.3%, which was significantly greater in those with more marked inflammation, that is, higher neutrophil counts, C-reactive protein levels, and interleukin-6 levels. These two studies suggest that inflammation plays a synergistic role with ammonia in producing and modulating MHE. Another link between inflammation, ammonia and MHE is through gut flora and endotoxins. Indeed, lactulose, the most commonly used standard therapy for HE, works in part by altering gut flora to decrease ammonia production and absorption. Zhao et al.87 demonstrated varying degrees of imbalance of intestinal flora among cirrhotics compared to normal healthy controls; there was increase in the counts of aerobes (such as Enterobacter and Enterococcus) and anaerobes (such as Clostridium) MCE公司 and a decrease in the count of Bifidobacterium. The severity of imbalance in gut flora matched the degree of liver dysfunction, with the most serious imbalance observed

in patients in Child–Turcotte–Pugh (CTP) class C. Liu et al.65 found that cirrhotic patients with MHE had substantial derangements in the gut microecology, with significant fecal overgrowth of potentially pathogenic Escherichia coli and Staphylococcus species. Treatment with synbiotics significantly increased the fecal content of non-urease-producing Lactobacillus species at the expense of these other bacterial species. Such modulation of gut flora was associated with a significant reduction in blood ammonia levels and reversal of MHE in 50% of patients. Synbiotic treatment was also associated with a significant reduction in endotoxemia. The CTP functional class improved in nearly 50% of the patients. 37 Ammonia plays a key role in the pathogenesis of MHE. Ammonia has deleterious effects on brain metabolism and neurotransmission. (1b) The frequency of MHE increases as the severity of liver disease increases.