Correction of altered plasma amino acid pattern in cirrhosis of the liver by somatostatin

Association of eNOS Gene Polymorphisms G894T and T-786C with Risk of Hepatorenal Syndrome

Background. There are no studies investigating the relationship between endothelial nitric oxide synthase (eNOS) gene polymorphisms and hepatorenal syndrome (HRS). Aim. The purpose of this study is to elucidate whether eNOS gene polymorphisms (G894T and T-786C) play a role in the development of type-2 HRS. Methods. This study was carried out in a group of 92 patients with cirrhosis (44 patients with type-2 HRS and 48 without HRS) and 50 healthy controls. Polymorphisms were determined by polymerase chain reaction (PCR) and melting curve analysis. Results. We did not find any significant difference in allele and genotype distributions of the eNOS -T-786C polymorphism among the groups (p = 0.440). However, the frequency of GT (40.9%) and TT (13.6%) genotypes and mutant allele T (34.1%) for the eNOS G894T polymorphism were significantly higher (p < 0.001 and p < 0.001, resp.) in the HRS group than in both the stable cirrhosis (14.6%, 4.2%, and 11.5%, resp.) and the control (22.0%, 2.0%, and 13.0%, resp.) groups. Conclusion. The occurrence of mutant genotypes (GT/TT) and mutant allele T in eNOS -G894T polymorphisms should be considered as a potential risk factor in cirrhotic patients with HRS.

A metabonomic analysis of serum from rats treated with ricinine using ultra performance liquid chromatography coupled with mass spectrometry

A metabonomic approach based on ultra performance liquid chromatography coupled with mass spectrometry (UPLC/MS) was used to study the hepatotoxicity of ricinine in rats. Potential biomarkers of ricinine toxicity and toxicological mechanism were analyzed by serum metabonomic method. The significant differences in the metabolic profiling of the control and treated rats were clear by using the principal components analysis (PCA) of the chromatographic data. Significant changes of metabolite biomarkers like phenylalanine, tryptophan, cholic acid, LPC and PC were detected in the serum. These biochemical changes were related to the metabolic disorders in amino acids and phospholipids. This research indicates that UPLC/MS-based metabonomic analysis of serum samples can be used to predict the hepatotoxicity and further understand the toxicological mechanism induced by ricinine. This work shows that metabonomics method is a valuable tool in drug mechanism study.

Clofibrate-induced reduction of plasma branched-chain amino acid concentrations impairs glucose tolerance in rats

It has been reported that branched-chain amino acid (BCAA) administration stimulates glucose uptake into muscles and whole body glucose oxidation in rats. The authors examined the effect of decreased plasma BCAA concentrations induced by clofibrate treatment on glucose tolerance in rats. Since clofibrate, a drug for hyperlipidemia (high serum triglyceride concentration), is a potent inhibitor of the branched-chain α-keto acid dehydrogenase kinase, clofibrate treatment (0.2 g/kg body weight) activated the hepatic branched-chain α-keto acid dehydrogenase complex, resulting in decreased plasma BCAA concentrations by 30% to 50% from the normal level. An intraperitoneal glucose tolerance test was conducted after clofibrate administration, and the results showed that peak plasma glucose concentration and the area under the curve of glucose concentration during the intraperitoneal glucose tolerance test were significantly higher in clofibrate-treated rats than in control rats. This impaired glucose tolerance in the clofibrate-treated rats was ameliorated by administration of BCAAs (0.45 g/kg body weight, leucine:isoleucine:valine = 2:1:1), which kept plasma BCAA concentrations at normal levels during the intraperitoneal glucose tolerance test. These results suggest that plasma BCAAs play an important role in maintaining normal glucose tolerance in rats.

Increased plasma nitric oxide, L-arginine, and arginase-1 in cirrhotic patients with progressive renal dysfunction

BACKGROUND AND AIMS

Increased levels of nitric oxide (NO) are hypothesized to contribute to renal dysfunction in patients with decompensated cirrhosis. In this study, we examined whether splanchnic and/or peripheral NO levels and L-arginine (L-Arg) correlate with progressive renal dysfunction in cirrhotics.

METHODS

Serum NO metabolites (NOx) and L-Arg were measured in: controls (n = 10); organ donors (n = 12); compensated cirrhotics (n = 17), cirrhotics with ascites (n = 25), refractory ascites (n = 11) or hepatorenal syndrome type II (HRS) (n = 11) and chronic renal failure patients (n = 18).

RESULTS

Plasma NOx and L-Arg levels rose progressively with worsening renal function in decompensated cirrhotics. Both NOx and L-Arg levels were highest in patients with HRS (P < 0.001 and P < 0.025, respectively). While there were no differences in NOx levels related to the site of sampling, L-Arg levels were lowest in hepatic venous blood. There were significant relationships of NOx and L-Arg with Model for End-Stage Liver Disease score and Child-Pugh scores (P < 0.04 and P < 0.01, respectively). Multivariate analysis showed a significant relationship between NOx, L-Arg and HRS.

CONCLUSION

Worsening renal function in decompensated cirrhosis is accompanied by progressive elevation in plasma NOx and L-Arg. These findings support the hypothesis that NO-mediated vasodilation is probably linked with the mechanism of progressive renal failure in decompensated cirrhotics.

Altered alanine plasma levels despite normalized hepatic alanine extraction in the long-term course after liver transplantation

BACKGROUND

The amino acid (AA) metabolism in cirrhosis is deranged, reflected by an altered plasma AA profile. Alanine is a unique AA with predominant production by muscle and the highest hepatic extraction rate.

METHODS

We studied circulating levels and hepatic alanine extraction in 52 patients with advanced cirrhosis, 16 stable patients more than 6 months after orthotopic liver transplant (OLT), and 50 controls. In addition, hepatic hemodynamics (portal pressure, hepatic blood flow, and splanchnic percent indocyanine green extraction) and parameters of hepatic metabolism (splanchnic oxygen uptake and splanchnic glucose production) were assessed.

RESULTS

Circulating alanine levels decreased independently of the clinical stage in cirrhosis (262+/-15 micromol/L vs. 330+/-14 micromol/L in controls, P<0.001) and decreased even further after OLT (209+/-10 micromol/L, P<0.001). Hepatic alanine extraction decreased dependently on the clinical stage in cirrhosis (59+/-7 micromol/min) and was normalized after OLT (100+/-10 micromol/min, P<0.001), indicating that decreased plasma alanine levels in OLT patients are the result of changes in extrahepatic metabolism. Hepatic alanine extraction correlated with splanchnic oxygen uptake (r=0.64, P<0.001) and hepatic glucose production (r=0.65, P<0.001).

CONCLUSIONS

These results demonstrate that significant alterations in muscular AA metabolism persist even in the clinically stable long-term course after OLT when the hepatic AA metabolism is normalized.

Plasma amino acids in cirrhosis and after liver transplantation: influence of liver function, hepatic hemodynamics and circulating hormones

Liver cirrhosis is characterized by substantial changes in amino acid (AA) metabolism, resulting in a deranged plasma AA profile. To investigate the effect of liver transplantation (OLT), we studied arterial AA profiles in 52 patients with advanced cirrhosis, 16 stable patients over 6 months after OLT and 48 controls. Changes in AA levels were correlated with portal pressure (hepatic venous pressure gradient), functional hepatic blood flow (indocyanine green extraction) and circulating hormone levels (catecholamines, insulin, C-peptide). Fourteen of 18 measured AA were significantly altered in cirrhosis and 11 of 18 remained abnormal after OLT compared with controls. Aromatic AA (AAA) and methionine were elevated in cirrhosis (p < 0.001 each), increasing with disease stage, and normalized after OLT. Branched chain AA (BCAA) levels were decreased in cirrhosis (p < 0.001) and were unrelated to disease stage. After OLT, BCAA levels remained subnormal (p < 0.01), although higher than in cirrhosis (p < 0.001). AAA levels increased with decreasing functional hepatic blood flow (r = -0.67; p < 0.001) and increasing portal pressure (r = 0.59; p < 0.001). BCAA levels decreased with increasing catecholamine (r = - 0.54, p < 0.001) and insulin levels (r = - 0.40, p = 0.001). We conclude that despite normal liver function, AA metabolism is only partially normalized after OLT. AAA levels mainly determined by hepatic metabolic function and functional liver blood flow return to normal, while BCAA levels remain subnormal, indicating persistent changes in muscular AA metabolism after OLT.

Effect of mesocaval interposition shunting and repeated sclerotherapy on blood levels of gastrointestinal regulatory peptides, amino acids, and lysosomal enzymes--a prospective randomised trial

AIMS/BACKGROUND

Patients with liver cirrhosis and portal hypertension frequently exhibit a multitude of alterations of hormones and metabolism, but the relation of these alterations to liver function, degree of blood shunting, and hepatic encephalopathy remains unclear.

METHODS

Twenty-four patients were randomised to mesocaval interposition shunt (MIS) and 21 patients to repeated sclerotherapy (ST). Several peptide hormones, amino acids and lysosomal enzymes were monitored during a 4 year follow-up period.

RESULTS

Insulin and glucagon levels were elevated in the MIS group compared to pre-therapy levels, whereas the gastrin level was significantly higher in the ST group. Pancreatic polypeptide, somatostatin and vasoactive intestinal peptide levels were not affected by either treatment. The branched chain amino acids valine, leucine and isoleucine serum levels were all elevated after ST, and the arginine, proline and tyrosine levels were higher in the MIS group at follow-up. Other amino acids were not changed, neither were the lysosomal enzymes beta-hexosaminidase nor beta-glucoronidase during this longterm follow-up.

CONCLUSION

MIS or repeated ST treatment only affected serum levels of hormones, amino acids and lysosomal enzymes to a limited extent. In this trial, the type of treatment had only a small influence on these parameters during long term follow-up.

Intravenous and subcutaneous administration of a long-acting somatostatin analogue: effects on glucose metabolism and splanchnic haemodynamics in healthy subjects

The effect of SMS 201-995, a long-acting somatostatin analogue, on splanchnic blood flow and glucose metabolism, was investigated in five groups of healthy subjects. Groups A (n = 4), B (n = 5), C (n = 5) and D (n = 5) were studied before, during and after a 60-min intravenous infusion of SMS (1.7, 0.8, 0.2 and 0.1 micrograms min-1, respectively). Group E (n = 6) was investigated before and for 6 h after a subcutaneous injection of 25 micrograms of SMS. The splanchnic blood flow decreased by 20-25% in all groups in response to SMS and remained low during the entire observation periods. Arterial concentrations of glucose showed a 15-20% decline during SMS infusion in Groups A and B (P less than 0.05-0.01) and a less pronounced decrease in the other groups. Fifteen minutes after the end of infusion the glucose levels started to rise and in group A, the levels were significantly higher than basal (+25%, P less than 0.05-0.01) at 90-180 min after the end of infusion. The net splanchnic glucose production, determined in groups A and B, decreased by 65-75% in response to SMS infusion. Towards the end and immediately after the infusions, however, the net glucose output increased, but decreased again at 30-60 min after the end of infusion. Arterial, insulin and glucagon concentrations decreased significantly during infusion in all groups. This decline was more pronounced for insulin (50%) than for glucagon (20-25%) and insulin concentrations remained low for a longer period after the end of infusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Pancreatic hormones and amino acid levels following liver transplantation

Glucose intolerance, hyperinsulinemia, peripheral insulin resistance and hyperglucagonemia are common in patients with advanced liver disease. These abnormalities in the plasma levels of the pancreatic hormones, insulin and glucagon have been thought to be responsible, at least in part, for the abnormal plasma ratio of branched-chain amino acids to aromatic amino acids. To evaluate this issue, plasma levels of glucose, insulin, glucagon, C-peptide and the branched-chain and aromatic amino acids were measured before and serially after orthotopic liver transplantation in 9 humans and 5 dogs. The abnormal plasma amino acid levels rapidly improved and achieved normal levels following orthotopic liver transplantation. Insulin levels also became normal following orthotopic liver transplantation, despite enhanced insulin secretion documented by an even further increased level of C-peptide. In contrast, the baseline abnormal plasma glucagon levels which are commonly seen in cirrhotics became even more abnormal following orthotopic liver transplantation. Despite this progressive increase in the abnormally elevated plasma glucagon levels, plasma amino acid levels, both branched-chain and aromatic, became normal. These data demonstrate that before and after orthotopic liver transplantation, there is: (i) no relationship between the changes in the plasma levels of glucagon and changes observed in the plasma level of amino acids; and (ii) plasma insulin and amino acid levels change in the same direction. In addition, these changes in plasma insulin and amino acid levels following orthotopic liver transplantation occur despite enhanced secretion of insulin evidenced by the progressive increase in plasma levels of C-peptide.