Role of bilirubin overproduction in revealing Gilbert's syndrome: is dyserythropoiesis an important factor? (1/56)

Gilbert's syndrome was diagnosed in 37 patients with unconjugated hyperbilirubinaemia without overt haemolysis or structural liver abnormality, who had a marked reduction in hepatic bilirubin UDP-glucuronosyltransferase activity (B-GTA) (as compared with that of 23 normal subjects). No significant correlation existed in these patients between serum bilirubin level and the values of B-GTA, thus suggesting that factors other than a low B-GTA must influence the degree of hyperbilirubinaemia in Gilbert's syndrome. Studies of 51Cr erythrocyte survival and 59Fe kinetics in 10 unselected patients demonstrated slight haemolysis in eight, whereas mild ineffective erythropoiesis was suggested in all from a low 24-hour incorporation of radioactive iron into circulating red cells. This overproduction of bilirubin resulting from mild haemolysis and perhaps dyserythropoiesis might reflect only an extreme degree of the normal situation. It certainly contributes to the hyperbilirubinaemia of Gilbert's syndrome and may play a major role in the manifestation of this condition.  (+info)

Involvement of an organic anion transporter (canalicular multispecific organic anion transporter/multidrug resistance-associated protein 2) in gastrointestinal secretion of glutathione conjugates in rats. (2/56)

We investigated the role of cMOAT/MRP2 (canalicular multispecific organic anion transporter/multidrug resistance-associated protein 2) in the intestinal secretion of organic anions by comparing the behavior in Sprague-Dawley (SD) rats and Eisai hyperbilirubinemic rat (EHBR) whose cMOAT/MRP2 is hereditarily defective. After i.v. administration of 1-chloro-2,4-dinitrobenzene (30 micromol/kg), the biliary and intestinal excretion of its glutathione conjugate 2, 4-dinitrophenyl-S-glutathione (DNP-SG), a substrate for cMOAT/MRP2, was significantly reduced in EHBR compared with SD rats. This result also was confirmed by Ussing chamber studies; DNP-SG showed 1.5-fold greater serosal-to-mucosal flux compared with the mucosal-to-serosal flux in SD rats, whereas a similar flux was observed in both directions in EHBR. In addition, metabolic inhibitors reduced the preferential serosal-to-mucosal flux of DNP-SG in SD rats. In everted sac studies, intestinal secretion clearance, defined as the efflux rate of DNP-SG into the mucosal side divided by the area under the curve on the serosal side, was significantly lower in the jejunum of EHBR than that in SD rats. Northern blot analyses demonstrated the highest mRNA level of cMOAT/MRP2 in the jejunum, which is in good agreement with the results of the everted sac studies. These results suggest that cMOAT/MRP2 is involved in the secretion of organic anions in the small intestine.  (+info)

Stimulation of defective Gunn-rat liver uridine diphosphate glucuronyltransferase activity in vitro by alkyl ketones. (3/56)

Addition of alkyl ketone (10mM) to Gunn-rat liver homogenates increased UDP-glucuronyltransferase activity towards 2-aminophenol by 10--20 fold, up to enhanced values of enzyme activity observed with similarly treated Wistar-rat liver homogenates. Alkyl ketones also activate the defective enzyme purified from Gunn-rat liver. This genetic deficiency of UDP-glucuronyltransferase activity is no longer apparent when assayed in the presence of alkyl ketones.  (+info)

Liver ultrastructure in Gilbert's syndrome. (4/56)

Electron microscopy of hepatic tissue obtained by percutaneous needle biopsy from nine patients with Gilbert's syndrome has revealed in every case gross hypertrophy of hepatocyte agranular endoplasmic reticulum but no other important abnormality. While this may have relevance to impairment of microsomal enzyme activity controlling bilirubin conjugation within liver cells, the serum bilirubin levels in all nine patients were below that normally associated with demonstrable UDP-glucuronyl transferase deficiency. Gross hypertrophy of agranular endoplasmic reticulum may be, therefore, a constant feature of this form of Gilbert's syndrome and may have some diagnostic value in the investigation of unconjugated hyperbilirubinaemia.  (+info)

The urinary concentrating defect in the Gunn strain of rat. Role of bilirubin. (5/56)

The role of high serum and tissue levels of unconjegated bilirubin in the pathogenesis of the impaired urinary concentrating ability was investigated in homozygous (jj) Gunn rats with the congenital absence of hepatic glucuronyl transferase. Continuous phototherapy with blue fluorescent lights at a wave length of 460 nm or oral cholestyramine feeding or both reduced serum levels of unconjugated hilirubin to levels consistently below 3.0 mg/100 ml for several weeks in both weanling and adult jj Gunn rats. The renal concentrating defect was already present in weanling jj Gunn rats by 21 days of age. In treated weanling jj animals, maximum concentrating ability and the concentration of urea and nonurea solutes in the papilla and medulla, determined after 24 h of fluid deprivation, were normal when compared to unaffected heterozygous (Jj) littermates. Solute-free water reabsorption which is reduced in jaundiced jj Gunn rats was restored to normal in treated weanling jj rats. The tissue concentration of unconjugated bilirubin was reduced throughout the papilla and inner and outer medulla in the treated jj rats in comparison with untreated jj littermates. The defect in urinary concentrating ability was only partially reversible and sometimes irreversible in adult jj rats, probably because of permanent renal parenchymal damage occurring secondary to massive crystalline deposits in the papilla and medulla. It is concluded that unconjugated bilirubin is directly involved in the pathogenesis of the concentrating defect in jaundiced jj Gunn rats.  (+info)

Population studies on Gilbert's syndrome. (6/56)

Total serum bilirubin concentration was measured by an Autoanalyzer technique in 197 normal males and 102 normal females. The mean bilirubin concentration was significantly lower in the females than in the males. Total bilirubin concentration in the males showed a bimodal distribution with an antimode at 24 mumol/1 (1.4 mg/100ml). Individuals with bilirubin concentration above this value had unconjugated hyperbilirubinaemia and probable Gilbert's syndrome. Total bilirubin concentration in the females again showed a bimodal distribution with an antimode at 12 mumol/1 (0.7 mg/100ml). It is conceivable that females with bilirubin levels above this also have Gilbert's syndrome. This suggests that the population incidence of Gilbert's syndrome could be as high as 6% and that the sex incidence is approximately equal.  (+info)

Comparison of treatments for congenital nonobstructive nonhaemolytic hyperbilirubinaemia. (7/56)

A patient with Crigler-Najjar disease has survived with the help of phototherapy to the age of 2 years without neurological damage. Because long periods of phototherapy are a threat to normal development, a search was made for supplementary treatments. Cholestyramine and a high fat diet were effective, and possibly also aspartic acid. Maintenance therapy with cholestyramine allowed the amount of phototherapy given to be reduced.  (+info)

Effect of dietary composition on the unconjugated hyperbilirubinaemia of Gilbert's syndrome. (8/56)

The influence of dietary composition on the unconjugated hyperbilirubinaemia of Gilbert's syndrome was studied in 29 patients. After a period on a normal diet (10 MJ) an intravenous infusion of 40% glucose (8-4 MJ) together with a 1-6 MJ oral diet for two days resulted in an increment in plasma bilirubin concentration of 127 +/- 18% (mean +/- SEM) above the basal level. Both the administration of intravenous Intralipid 20% and the return to a normal diet caused a prompt reversal of this glucose effect. An increment of 135 +/- 10% in plasma bilirubin concentration was obtained when a standard "fasting" diet (1-6 MJ) was given for two days. When the lipid content of this "fasting" diet was increased from 33% to 85%, the rise in plasma bilirubin was only 49 +/- 19%. A 10 MJ oral diet for three days, which contained most of its energy content as carbohydrate and only 0-6% as lipid, produced a 76 +/- 12% increase in plasma bilirubin concentration. When the lipid content of the diet was increased to 9% of the energy intake no significant change from the basal level was observed. These findings support the hypothesis that the hyperbilirubinaemia associated with both carbohydrate feeding and fasting is attributable, at least in part, to lipid withdrawal. Although a restricted dietary intake or the parenteral administration of lipid-free solutions has a marked effect on the hyperbilirubinaemia of patients with Gilbert's syndrome, normal daily variation in dietary composition is unlikely to cause a significant change. The influence of different feeding regimes on neonatal hyperbilirubinaemia requires investigation.  (+info)