Detection of photobilirubin in urine of jaundiced infants supporting the diagnosis of ‘bronze baby syndrome’

Meisel, Peter; Jährig, D; Meisel, M.

doi:10.1016/0009-8981(87)90195-1

Cited by 5 publications

(3 citation statements)

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“…The excess Cu(I1) ions could overcome the binding capacity of endogenous serum and liver proteins. Such a mechanism for the onset of BBS is in agreement with the known deranged liver function and cholestasis in BBS patients (6,23), whereas the need for the simultaneous presence of cholestasis, hyperbilirubinemia, and phototherapy would explain the rare occurrence of this syndrome. To check the validity of our hypothesis, we developed an animal model where rats were artificially made cholestatic and hyperbilirubinemic.…”

Section: Resultssupporting

confidence: 79%

“…At the same time, one can DISCUSSION The exact nature of the pigments responsible for the bronze color of the skin in neonates developing BBS is still debatable. The involvement of photoisomerization and photooxidation products of bilirubin (7,23) and biliverdin-related compounds (24) has been proposed. However, previous studies from our laboratory (8,9) pointed out the presence of abnormally high serum concentrations of copper-porphyrins in those hyperbilirubinemic neonates developing BBS upon phototherapy; bluelight irradiation of these porphyrins in the presence of bilirubin yields brown photoproducts whose spectral features closely resemble those typical of sera isolated from BBS patients (lo, 24).…”

Section: Resultsmentioning

confidence: 99%

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Bronze Baby Syndrome: An Animal Model

1990

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ABSTRACT. We evaluated the appropriateness of an animal model for the bronze baby syndrome. Ligation of the common bile duct in adult Wistar rats induces an accumulation of porphyrins and copper in the liver and a 20% conversion of protoporphyrin IX into Cu(I1)-protoporphyrin IX. Upon irradiation of these animals with superblue lamps, the plasma content of Cu(I1)-protoporphyrin increases by about 30%. Cholestasis also increases the recovery of porphyrins in the urine, although light treatment of ligated rats further increases urinary porphyrin excretion. The spectroscopic changes induced by irradiation of sera of ligated rats are consistent with the formation of products that have the typical spectrum found in bronze baby syndrome patients, i.e. a reduced absorbance in the visible region and an increased absorption in near-UV and red spectral regions. The products responsible for the brown discoloration found in bronze baby syndrome seem to result from phototransformation of copper-porphyrins subsequent to an electron transfer between photoexcited bilirubin and the copper ion. who observed a newborn infant with a gray-brown discoloration after phototherapy for unconjugated hyperbilirubinemia. Subsequent reports (2-6) described the clinical aspects of this syndrome, whereas other studies attempted to clarify the biochemical mechanisms leading to BBS (7-9). In 1982, large amounts of porphyrins were demonstrated in sera of BBS patients (8). These were identified as Cu-uro-, Cu-copro-, and Cu-protoporphyrin (9). In addition, large amounts of porphyrins were detected in sera of adult and pediatric patients with cholestatic disorders (10). The proposed mechanism for the onset of BBS invokes, first, the presence of cholestasis, causing elevated copper and porphyrin concentrations in serum, and second, hyperbilirubinemia and phototherapy (9-1 1). Cu-porphyrins undergo photodestruction, sensitized by bilirubin, to products that have generalized absorption in the near UV and red spectral regions and therefore are responsible for the brown discoloration (9-1 1).To shed further light on the mechanisms of development of this syndrome, we evaluated an animal model of BBS using Wistar rats subjected to ligation of the common bile duct. This strain of animals was chosen because in preliminary experiments we observed a consistent serum level of both conjugated and unconjugated bilirubin after common bile duct ligation. The results of these experiments were similar with those obtained by using heterozygous Gunn rats (12). MATERIALS AND METHODSChemicals. Bilirubin IX was purchased from Serva (Heidelberg, FRG) and used without further purification. Its concentration was evaluated by absorbance measurements at 460 nm using a molar extinction coefficient 164 000 M-' cm-' (ethanol solution) (13). All the free base porphyrins used were obtained from Porphyrin Products (Logan, UT) and converted into their Cu(I1) derivatives by reaction with cupric acetate (14). SDS was the product of Merck (Darmstadt, FRG). All other chemicals were comm...

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Bronze Baby Syndrome: An Animal Model

1990

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“…Insufficient excretion of bilirubin isomers by the liver in the Bronze Baby Syndrome, the photoisomers accumulate in patient serum. In periods of low concentration of bilirubin isomers in the urine, fluorescent porphyrins are often detected [32]. These results suggest that porphyrin-induced singlet oxygen formation and superoxide formed through redox cycling of porphyrin [33] contribute to the fragmentation of bilirubin whether free or conjugated.…”

Section: Resultsmentioning

confidence: 93%