Mt Vilei

Bilirubin inhibits bile acid induced apoptosis in rat hepatocytes.

Background and aims: Hydrophobic bile acids contribute to hepatocellular injury in cholestasis and rapidly induce apoptosis in vitro; however, unlike Fas agonists, cholestasis does not cause extensive hepatocyte apoptosis. As antioxidants provide protection against bile acid induced liver injury, our premise was that bilirubin, a free radical scavenger with increased plasma levels in the presence of liver disease, could protect hepatocytes against bile acid induced apoptosis. Methods: Freshly isolated rat hepatocytes were incubated for four hours with 100 μmol/l glycochenodeoxycholate (GCDC) alone or with increasing concentrations of unconjugated (UCB) or conjugated (CB) bilirubin. Results: Both UCB and CB inhibited GCDC induced apoptosis in a dose dependent fashion and suppressed the generation of reactive oxygen species by hepatocytes. Conclusions: The antiapoptotic effect of bilirubin associated with its antioxidant properties indicates that hyperbilirubinaemia may have a protective role in liver disease.

Neonatal bilirubin production-conjugation imbalance: Effect of glucose-6-phosphate dehydrogenase deficiency and borderline prematurity

Objective: To evaluate relations between production and conjugation of bilirubin in the pathophysiology of jaundice in glucose-6-phosophate dehydrogenase (G6PD) deficient neonates. Methods: Term and borderline premature (35–37 weeks gestational age), healthy, male, G6PD deficient neonates were studied close to the beginning of the 3rd day. Blood carboxyhaemogobin corrected for inspired CO (COHbc; an index of bilirubin production) and serum total conjugated bilirubin (TCB; a reflection of bilirubin conjugation) were measured in simultaneously drawn blood samples by gas chromatography and reverse phase high performance liquid chromatography respectively. A bilirubin production-conjugation index comprising COHbc/TCB was determined; a high index reflects imbalance between the bilirubin production and conjugation processes. COHbc and TCB individually and the production-conjugation index were studied in relation to serum total bilirubin (STB) concentration. Results: Fifty one G6PD deficient neonates were sampled at 51 (8) hours. COHbc values did not correlate with STB (r u200a=u200a 0.22, p u200a=u200a 0.15). TCB did correlate inversely with STB (r u200a=u200a −0.42, p u200a=u200a 0.004), and there was a positive correlation between the production-conjugation index and STB (r u200a=u200a 0.45, p u200a=u200a 0.002). The production-conjugation index (median (interquartile range)) was higher in the premature (n u200a=u200a 8) than term neonates (2.31 (2.12–3.08) v 1.05 (0.53–1.81), p u200a=u200a 0.003). This difference was the result of changes in TCB. Conclusions: The data show that jaundice in G6PD deficient neonates is the result of an imbalance between production and conjugation of bilirubin with a tendency for inefficient bilirubin conjugation over increased haemolysis in its pathogenesis. Borderline premature infants are at especial risk of bilirubin production-conjugation imbalance.

Comparison of pig, human and rat hepatocytes as a source of liver specific metabolic functions in culture systems--implications for use in bioartificial liver devices.

The limited availability of human hepatocytes results in the use of animal cells in most bioartificial liver support devices. In the present work, clinically relevant liver specific metabolic activities were compared in rat, pig and human hepatocytes cultured on liver-derived biomatrix to optimize the expression of differentiated functions. Pig hepatocytes showed higher rates of diazepam metabolism (2.549±0.821 μg/h/million cells vs. 0.474±0.079 μg/h/million cells rats, p<0.005, and vs. 0.704±0.171 μg/h/million cells in man, p<0.005) and of bilirubin conjugation (21.60116±8.433237 μmoles/l/24 h vs. 6.786809±2.983758 in man, p<0.001 and vs. 9.956538±1.781016 μmoles/l/24 h in rats, p<0.005). Urea synthesis was similar in pig and in human hepatocytes (150±46.3 vs. 144.8±21.46 nmoles/h/million cells) and it was lower in rats (84.38±35.2; p<0.001 vs. man, p<0.02 vs. pig). High liver specific metabolic activities in cultured pig hepatocytes further support their use as a substitue for human cells in bioartificial liver devices

Serum bile acids and esterified bilirubin in early detection and differential diagnosis of hepatic dysfunction following orthotopic liver transplantation

Routine laboratory tests are of little help for early detection and differential diagnosis of hepatic dysfunction following orthotopic liver transplantation (OLT). In the present study, serum levels of esterified bilirubin, total bilirubin and bile acids were investigated in 20 patients after OLT. Twenty episodes of liver dysfunction were observed: 10 rejection episodes, 3 cases of thrombosis of the hepatic artery, 3 cases of septic shock, and 4 episodes of cyclosporin toxicity. During rejection, the median increase in esterified bilirubin was 3.2-fold (range 1.6-24.9), while total bilirubin increased 1.5-fold (range 0.7-3.4). Bile acids increased 3.6-fold (range 2.5-6.6; peak levels 25-87 microM). Both bile acids and esterified bilirubin increased 1-3 days earlier than serum transaminases and decreased only after successful anti-rejection treatment. The response of bile acids to successful treatment was usually more rapid than the response of esterified bilirubin. Hepatic artery thrombosis and septic shock were associated with a sharp increase in esterified bilirubin and very high bile acid levels (peak levels 80-185 microM). During cyclosporin toxicity, a characteristic pattern of progressively increasing bilirubin with no change in the bile acid levels was observed. Both esterified bilirubin and bile acids are very sensitive indicators of hepatic graft dysfunction. In particular, serum bile acids are useful for identifying cyclosporin toxicity and monitoring the response to anti-rejection treatment.

Acute effects of HMG-CoA reductase inhibitors on biliary lipids in patients with interrupted enterohepatic circulation

Abstract. HMG‐CoA reductase inhibitors decrease serum cholesterol by inhibiting hepatic cholesterol synthesis, but their influence on biliary lipids is not well characterized. In the present study Pravastatin (80 mg) was administered as a single oral dose to 10 patients with external bile fistula, after 1 week of interruption of the enterohepatic circulation, in order to assess the effect of inhibition of hepatic cholesterol synthesis on biliary lipids in conditions of stimulated bile acid synthesis. Bile was collected every hour for 12 h. On the day before, the same procedure was applied with a placebo, and collected bile used as control. Pravastatin decreased both bile acid and phospholipid concentration to about 60% of basal values; this change was still significant after 10 h. Cholesterol concentration was also decreased to about 70% of basal values, but this change was significant only from the 5th to the 7th h. The per cent of cholic and chenodeoxycholic acid was not affected by the drug, but the ratio of glyco‐ to tauroconjugated bile acids was decreased to about half the initial values. Bilirubin concentration exhibited a late increase, suggesting a reduction in the bile flow. These results suggest that, in patients with interrupted enterohepatic circulation, biliary excretion of bile acids can be largely dependent on hepatic cholesterol synthesis.

Ultrasonic evaluation of gallbladder emptying with ceruletide: comparison to oral cholecystography with fatty meal

Assessment of gallbladder function is required prior to nonsurgical treatment of gallstones. In order to develop a practical and reproducible method of evaluation, gallbladder emptying was studied by ultrasound (US) in 55 gallstone patients after intramuscular administration of ceruletide (0.3 μg/kg). In 27 of these subjects, the US procedure was compared to oral cholecystography (OCG) with fatty meal. Maximal percent gallbladder contraction was reached 30 min after ceruletide in all patients. Maximal percent contractions were 47.5±27.7 during US with ceruletide and 33.9±16.3 during OCG with fatty meal (p = 0.03). A significant linear relationship was found between the results obtained with the two different procedures (r=0.57; p = 0.002). Serial US determinations of gallbladder emptying were performed in 16 patients. Individual variation was below 20% in 11 subjects, and in five subjects it ranged between 20 and 40%. Minor, self-limiting side effects were observed in 13 patients. US determination of gallbladder emptying after ceruletide appears to be a practical and reliable method to assess gallbladder function.