Glucuronide-Forming Enzymes

Dutton, Geoffrey J.

doi:10.1007/978-3-642-65177-9_24

Cited by 28 publications

(25 citation statements)

References 122 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reason for this low capacity is not known but is thought to be due to a combination of low UDP glucose dehydrogenase activity and low UDP transglucuronylase (i.e. glucuronyl trans ferase) activity (2). Studies of livers obtained from human fetuses up to the third month of gestation indicate absence of transglucuronylase activity (7).…”

Section: Discussionmentioning

confidence: 99%

“…Studies of livers obtained from human fetuses up to the third month of gestation indicate absence of transglucuronylase activity (7). Furthermore, questions have been raised as to whether a single enzyme is involved or if a family of closely related enzymes having different acceptor specificities catalyzes these glucuronidations (2,13). Because of these prob lems it is hazardous to discuss the general development of glucuronidation by hepatic microsomes isolated from the fetal monkey when the sample size is small and only one substrate has been utilized.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Drug Metabolism by the Fetal Stump-Tailed Monkey (<i>Macaca arctoides</i>)

Dvorchik¹,

Stenger²,

Hartman³

1979

Pharmacology

View full text Add to dashboard Cite

Sensitive radiometric assays were adapted to study the development and kinetics of meperidine and methadone N-demethyiation and morphine glucuronidation by microsomes isolated from livers of fetal stump-tailed macaques (Macaca arctoides). Times in development selected for study were midterm, three-quarter term, near term and newborn (0.5 hand 14 days). With appropriate attention to keeping blanks low, hepatic drug metabolism was demonstrable as early as midterm. V_max for the N-demethylation reactions (nmole product/10 min/mg microsomal protein) increased throughout gestation, whereas the apparent K_ms remained constant. With respect to morphine glucuronidation, all kinetic parameters remained constant throughout the last half of gestation.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Drug Metabolism by the Fetal Stump-Tailed Monkey (<i>Macaca arctoides</i>)

Dvorchik¹,

Stenger²,

Hartman³

1979

Pharmacology

View full text Add to dashboard Cite

show abstract

“…o-Aminophenyl glucuronide was measured by the method described by Dutton and Storey [1962], incubates for the estimation of UDPglucuronyl transferase activity consisting of sulphate-free Krebs-Henseleit solution containing o-aminophenol (0-23 mmol/l), ascorbic acid (1 mmol/l) and tissue.…”

Section: Methodsmentioning

confidence: 99%

Activities of Mixed Function Oxidases, Udp‐glucuronyl Transferase and Sulphate Conjugation Enzymes in Galliformes and Anseriformes

Bartlet

Kirinya

1976

Exp Physiol

View full text Add to dashboard Cite

The activities of certain drug metabolizing enzymes have been measured in liver and kidney slice preparations from domesticated birds. Aminopyrine demethylase activity was significantly lower in liver slices from the duck (Aylesbury x Pekin, KhakiCampbell) than from the rat (Wistar), and in the Aylesbury x Pekin duck lower than in the turkey (Triple 6 FLX), chicken (Brown Leghorn, Rhode Island Red x Light Sussex) and goose (Emden x Doulouse). The microsomal cytochrome P-450 was lower in duck liver (Aylesbury x Pekin) than in rat liver, and the aniline hydroxylase and aminopyrine demethylase activities in a 10,000 g supernatant fraction of liver were lower in duck preparations (Aylesbury x Pekin, Khaki-Campbell) than rat preparations. These observations suggest that the duck is likely to be susceptible to drugs which are metabolized by the cytochrome P-450 containing mono-oxygenases.UDP-Glucuronyl transferase activity was not detectable in liver and kidney slices from two mature geese. This observation was not the outcome of a deficiency of UDPglucuronic acid, rapid breakdown of glucuronide by ,B-glucuronidase or the presence of a substance inhibitory to UDP-glucuronyl transferase. Liver slices from geese, ducks (Aylesbury x Pekin) and chickens contained low UDP-glucuronyl transferase and high sulphate conjugation enzyme activities, whereas the reverse was found in Khaki-Campbell ducks. The activities of UDP-glucuronyl transferase and the sulphate conjugation enzymes were both relatively high in liver slices from the turkey and rat.The kidney contained lower enzyme activities than the liver except in the duck (Aylesbury x Pekin), in which low activities of aminopyrine demethylase and UDPglucuronyl transferase were present in slices of both organs.In liver slices from chickens and geese the activities of aminopyrine demethylase and the sulphate conjugation enzymes were similar in mature and immature birds, and the activity of UDP-glucuronyl transferase was considerably higher in chicks and goslings than in mature birds of the same species.In the chick the activities of aminopyrine demethylase, UDP-glucuronyl transferase and the sulphate conjugation enzymes were higher in the duodenum than the remainder of the alimentary tract. The activities of these enzymes in pieces of duodenum were as high as those in slices of liver.The inclusion of sulphate in the incubation medium produced a significant increase in the synthesis of p-nitrophenyl sulphate in liver slices and not kidney slices except those from the duck. The kidney slices seemed to produce sufficient sulphate for the reaction of the sulphate conjugation enzymes to proceed at the maximum rate, but the liver slices did not do so.Although domesticated birds sometimes exhibit great differences in susceptibility to foreign compounds, there is little information on the activities of enzymes which metabolize toxic substances in these species. In the present paper we describe experiments which compare the activities of mixed function

show abstract

“…The present study was, therefore, undertaken to evaluate the effect of maternally administered dexamethasone on the serum bilirubin levels of premature infants. Since the hepatic microsomal enzyme glucuronyl transferase (UDPGT), which is immature in the newborn infant [1, 8,24], plays a key role in the metabolism of both bilirubin and glucocorticoids [7], it was also of some interest to provide additional data by studying the influence of prenatal dexamethasone treatment on the urinary D-glucaric acid excretion of infants bom prematurely.…”

Section: Introductionmentioning

confidence: 99%