Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Over 60% of the analgesic/antipyretic drug acetaminophen is eliminated by glucuronidation, which competes with a toxifying pathway involving cytochromes P-450-catalyzed bioactivation to a hepatotoxic reactive intermediate. A genetic deficiency of bilirubin UDP-glucuronyl transferase (GT) occurs in 5 to 7% of the population (Gilbert's disease, Crigler-Najjar syndrome) and this could predispose such people to acetaminophen hepatotoxicity. This hypothesis was evaluated in the homozygous Gunn rat, which is similarly deficient in GT, and the heterozygous Gunn rat, which has intermediary GT activity. Acetaminophen, 1 g/kg, was administered by gavage to animals 6 and 11 weeks of age, and age-matched Wistar rats as controls. Hepatic and renal cellular damage were assessed by respective increases in the peak plasma concentration of alanine aminotransferase and the blood urea nitrogen concentration, and confirmed by histological examination. Acetaminophen and metabolites were measured by high-performance liquid chromatography. Compared to Wistar controls, Gunn rats demonstrated up to a 110-fold greater hepatotoxic response to acetaminophen, with significantly lower production of the glucuronide conjugate and higher plasma concentrations of acetaminophen. Elevated acetaminophen concentrations correlated positively with both increased production of the acetaminophen-cysteine conjugate, reflecting bioactivation and hepatotoxicity. Older Gunn but not Wistar rats showed up to 26-fold more hepatotoxicity compared to their younger counterparts. In younger animals, heterozygotes demonstrated intermediary hepatotoxicity between homozygotes and Wistar controls. Hepatotoxicity was similar in the older heterozygotic and homozygotic Gunn rats, as was renal toxicity, which was enhanced 2- to 3-fold over controls. These results indicate that a genetic deficiency in bilirubin GT can be an important determinant of acetaminophen bioactivation and toxicity.
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PMID:Deficiency in bilirubin UDP-glucuronyl transferase as a genetic determinant of acetaminophen toxicity. 313 68

Hepatic associated metabolic disorders represent 5% of the indications for orthotopic liver transplantation (OLTX) according to the European Liver Transplant Registry. We studied the outcome of this group at our institution after OLTX and combined liver/kidney transplantation. Between September 1988 and January 1997, 837 OLTXs were performed in 735 patients. Patient survival and graft function at 1 yr were 91.3 and 86%, respectively. Thirty-nine OLTXs were performed in 38 patients (15 female/23 male, median age +/- SD: 35 +/- 14 yr, range 4-60 yr) due to liver associated metabolic disorders (4.7%). Indications included Wilson's disease (n = 14), alpha-1-anti-trypsin-deficiency (n = 7), hemochromatosis (n = 4), erythropoetic protoporphyria (n = 4), cystic fibrosis (n = 2), Crigler-Najjar syndrome type I (n = 1), glycogenosis type I (n = 1), ornithine-transcarbomylase-deficiency (n = 1). In addition 4 patients suffering from primary hyperoxaluria type I received combined liver/kidney grafts. Survival rate the 1 yr after OLTX and combined OLTX/NTX was 91.8%. Twenty patients received cyclosporin A (55%) and 17 patients tacrolimus (45%) as primary immunosuppression. The mean follow-up was 28.6 months (range 4-73 months). Two patients with hemochromatosis died 1 and 3 months after OLTX, respectively, from Aspergillus sepsis followed by multiorgan-failure. One patient died of malignant lymphoma 5 months after transplantation. One patient required retransplantation 2 months after OLTX following arterial thrombosis and ischemic type biliary lesion. One year after OLTX, all patients demonstrated good graft function, liver grafts (ALT 17.9 +/- 13.6 IU/L, bilirubin 0.8 +/- 0.3.mg/dl, thromboplastin time 94 +/- 15%), and combined liver/kidney grafts (creatinine 2.4 +/- 1.4 mg/dl). OLTX, respectively combined OLTX/NTX, represent a successful therapy for hepatic associated metabolic disorders. Survival rates and graft function are similar to those in liver graft recipients for established indications at our institution. OLTX seems to be an excellent treatment for hepatic based therapy resistant neurological disorders.
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PMID:Orthotopic liver transplantation for hepatic associated metabolic disorders. 964 15

Crigler-Najjar syndrome is a recessively inherited disorder characterized by severe unconjugated hyperbilirubinemia caused by a deficiency of uridine diphospho-glucuronosyl transferase 1A1. Current therapy relies on phototherapy to prevent kernicterus, but liver transplantation presently is the only permanent cure. Gene therapy is a potential alternative, and recent work has shown that helper-dependent adenoviral (HD-Ad) vectors, devoid of all viral coding sequences, induce prolonged transgene expression and exhibit significantly less chronic toxicity than early-generation Ad vectors. We used a HD-Ad vector to achieve liver-restricted expression of human uridine diphospho-glucuronosyl transferase 1A1 in the Gunn rat, a model of the human disorder. Total plasma bilirubin levels were reduced from >5.0 mg/dl to <<1.4 mg/dl for >2 yr after a single i.v. administration of vector expressing the therapeutic transgene at a dose of 3 x 10(12) viral particles per kg. HPLC analysis of bile from treated rats showed the presence of bilirubin glucuronides at normal WT levels >2 yr after one injection of vector, and i.v. injection of bilirubins IIIalpha and XIIIalpha in the same animals revealed excess bilirubin-conjugating capacity. There was no significant elevation of liver enzymes (alanine aminotransferase) and only transient, moderate thrombocytopenia after injection of the vector. A clinically significant reduction in serum bilirubin was observed with a dose as low as 6 x 10(11) viral particles per kg. We conclude that complete, long-term correction of hyperbilirubinemia in the Gunn rat model of Crigler-Najjar syndrome can be achieved with one injection of HD-Ad vector and negligible chronic toxicity.
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PMID:Lifelong elimination of hyperbilirubinemia in the Gunn rat with a single injection of helper-dependent adenoviral vector. 1575 92

Crigler-Najjar syndrome type 1 (CN1) is an inherited disorder characterized by the absence of hepatic uridine diphosphoglucuronate glucuronosyltransferase (UDPGT), the enzyme responsible for the conjugation and excretion of bilirubin. We performed allogenic hepatocyte transplantation (AHT) in a child with CN1, aiming to improve bilirubin glucuronidation in this condition. A 9-year-old boy with CN1 was prepared with plasmapheresis and immunosuppression with prednisolone and tacrolimus. When a graft was made available, 7.5 x 10(9) hepatocytes were isolated and infused into the portal vein percutaneously. After 2 weeks phenobarbitone was added to promote the enzymatic activity of UDPGT of the transplanted hepatocytes. Nocturnal phototherapy was continued throughout the studied period. Total bilirubin was considered a reliable marker of allogenic cell function. There was no significant variation of vital signs nor complications during the infusion. Mean +/- SD bilirubin level was 530 +/- 38 micromol/L before and 359 +/- 46 micromol/L after AHT (t-test, p < 0.001). However, the introduction of phenobarbitone was followed by a drop of tacrolimus level with increase of alanine aminotransferase (ALT) and increase of bilirubin. After standard treatment of cellular rejection bilirubin fell again but from then on it was maintained at a greater level. After discharge the patient experienced a further increase of bilirubin that returned to predischarge levels after readmission to the hospital. This was interpreted as poor compliance with phototherapy. Only partial correction of clinical jaundice and the poor tolerability to nocturnal phototherapy led the parents to refuse further hepatocyte infusions and request an orthotopic liver transplant. After 24 months the child is well, with good liver function on tacrolimus and prednisolone-based immunosuppression. Isolated AHT, though effective and safe, is not sufficient to correct CN1. Maintenance of adequate immunosuppression and family compliance are the main factors hampering the success of this procedure.
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PMID:Isolated hepatocyte transplantation for Crigler-Najjar syndrome type 1. 1588 24

Crigler-Najjar syndrome is a rare disorder of bilirubin metabolism with two distinct forms: type 1 and type 2. We report three patients with Crigler-Najjar syndrome type 2 (CN-2). All patients had serum bilirubin values higher than 171 micromol/L and deep yellow skin color. The results of other liver function tests, glucose-6-phosphate dehydrogenase activity and hematology tests were normal, and immunologic tests for hepatitis A, B and C were negative, although one patient had slightly elevated alanine aminotransferase level (45 IU/L). Polymerase chain reaction and sequence analysis of the UDP-glucuronosyltransferase 1A1 (UGT1A1) gene revealed a novel homozygous T>A mutation at nucleotide 479 in exon 1 (Val160Glu) of patient 1, a novel homozygous A>G mutation at nucleotide 610 in exon 1 (Met204Val) of patient 2, and a homozygous T>G variation at nucleotide 1456 in exon 5 (Tyr486Asp) plus a heterozygous G>A variation at nucleotide 211 in exon 1 (Gly71Arg/normal) of patient 3. Two of these mutations were novel and variations identified within the coding region of the UGT1A1 gene were considered the cause of CN-2 in all three patients.
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PMID:Crigler-Najjar syndrome type 2. 1709 98