Albumin dialysis has a favorable effect on amino acid profile in hepatic encephalopathy

According to one popular theory, hepatic encephalopathy (HE) is partly caused by an imbalance in plasma amino acid levels. The Fischer's ratio between branched chain amino acids (BCAAs) and aromatic amino acids (AAAs) correlates with the degree of HE; the lower Fischer's ratio, the higher the grade of HE. Extra-corporeal liver support systems, like MARS(R)-albumin dialysis (Molecular Adsorbents Recirculating System), can improve HE. The MARS(R) system uses a hyperosmolar albumin circuit to remove both water-soluble and albumin-bound substances. Plasma levels of neuroactive amino acids were analyzed in 82 consecutive patients with life-threatening liver failure admitted to our ICU. All patients fulfilled our indications for MARS treatment and most also fulfilled the criteria for liver transplantation (LTx). In patients with acute liver failure (ALF), as compared to those with acute decompensation of chronic liver failure (AcOChr), levels of leucine and isoleucine were significantly higher before MARS(R) treatment. In all patients, before MARS(R) treatment the higher the grade of HE grade the lower was the Fischer's ratio and higher were the levels of inhibitory neuroactive amino acids. During MARS(R) treatments the Fischer's ratio increased, and the grade of HE decreased. The increase in Fischer's ratio was mainly due to the decrease in AAAs. The plasma levels of neuroactive amino acids, methionine, glutamine, glutamate, histidine and taurine decreased during MARS(R)-treatment. In this study MARS(R)-albumin dialysis had a favorable effect on the plasma amino acid profile of patients with HE.

Increased concentrations of histamine and its metabolite, tele-methylhistamine and down-regulation of histamine H3 receptor sites in autopsied brain tissue from cirrhotic patients who died in hepatic coma

BACKGROUND/AIMS

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication of chronic liver disease. To determine whether changes in the central histaminergic system are a feature of human HE, we studied histamine, tele-methylhistamine, and presynaptic autoregulatory H(3) receptors in cerebral cortex and caudate-putamen obtained at autopsy from six cirrhotic patients and six appropriately matched controls.

METHODS

Histamine was assayed by HPLC; tele-methylhistamine by GC-MS. H(3) receptors were studied by in vitro receptor binding using [3H]R-alpha-methylhistamine as ligand.

RESULTS

In HE patients, there was a significant fourfold increase of histamine in caudate-putamen and a significant increase in all cortical regions studied. tele-Methyhistamine was also increased and the densities of histamine H(3) receptor sites were significantly decreased in patient material.

CONCLUSIONS

These findings are consistent with activation of the histaminergic system in HE. Given that histamine participates in the regulation of arousal and circadian rhythmicity, they indicate that induction of central histamine mechanisms may contribute to the development of neuropsychiatric symptoms, such as sleep disturbances and altered circadian rhythms in chronic HE and suggest that pharmacological manipulation of the histaminergic system could be beneficial in the treatment of HE in chronic liver failure.