Karel P. M. Heirwegh

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1. In aqueous solution above pH7 bilirubin-IXalpha 1-O-acylglucuronide rapidly isomerizes to the non-C-1 glucuronides by sequential migration of the bilirubin acyl group from position 1 to positions 2, 3 and 4 of the sugar moiety. The transformations are enhanced by increasing the pH. Compared with the rates at 37 degrees C the transformations are rather(More)
1. The bilirubin UDP-glucuronyltransferase assay described by Van Roy & Heirwegh (1968) has been improved. 2. Extraction of final azo-derivatives is rendered more simple and efficient by thorough emulsification and by cooling. 3. Pretreatment of homogenates and cell fractions with digitonin increases the sensitivity of the assays and gives less variable(More)
1. T.l.c. with neutral solvent systems of ethyl anthranilate azopigments derived from bile of man, dog and rat revealed pronounced species variation. The less polar components (alpha-group) could be separated conveniently by development with chloroform-methanol (17:3, v/v). 2. The azopigment material derived from gallbladder bile of dog contained about 10%(More)
Bilirubin pigments were studied in the bile of 20 normal adults, 25 patients with Gilbert's syndrome, 9 children with Crigler-Najjar disease, and 6 patients with hemolysis, to determine how a deficiency of hepatic bilirubin UDP-glucuronosyltransferase would affect the end products of bilirubin biotransformation. In the bile from patients with Gilbert's(More)
The ability of porous bodies to distinguish between molecules of different sizes has been repeatedly observed. If these porous bodies are devoid of charged groups, solutes placed on top of a column filled with such a material will be partitioned chiefly by molecular sieve effect (1). Molecules with a size above a limiting value will leave the column(More)
The bilrubin-IXalpha conjugates in bile and the activities of bilirubin-IX alpha--UDP-glycosyltransferases in liver and kidney were determined for ten species of mammals and for the chicken. 1. In the mammalian species, bilirubin-IX alpha glucuronide was the predominant bile pigment. Excretion of neutral glycosides was unimportant, except in the cat, the(More)
Conjugates of bilirubin were studied in normal bile of man and rat, and in bile of liver patients. In general human bile was obtained by duodenal intubation. In addition T-tube bile was examined in patients operated on for mechanical obstruction. The bile pigment compositions of duodenal and T-tube bile were similar in two patients where comparison was(More)
1. Conjugated bilirubin is conveniently determined by coupling with the diazonium salt of ethyl anthranilate. 2. This method has been used in the development of assays for UDP-glucuronyltransferase (EC, with bilirubin as substrate, in rat liver homogenates, microsomal preparations and partly purified fractions. 3. Chromatographic analysis suggests(More)