2001年6月
Cyclobilirubin formation by in vitro photoirradiation with neonatal phototherapy light
PEDIATRICS INTERNATIONAL
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- 巻
- 43
- 号
- 3
- 開始ページ
- 270
- 終了ページ
- 275
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- 出版者・発行元
- BLACKWELL PUBLISHING ASIA
Background: The main mechanism of phototherapy for neonatal hyperbilirubinemia is the production and excretion of (EZ)- and (EE)-cyclobilirubin (4E,15Z- and 4E,15E-cyclobilirubin). Thus, the clinical efficacy of the light source for phototherapy must be evaluated by cyclobilirubin formation from (ZZ)-bilirubin in in vitro photoirradiation.
Methods: In the present study, we investigated the in vitro production pattern of bilirubin photoisomers by phototherapy light from the bilirubin-human serum albumin complex.
Results: No clear difference was found in the curves relative to (ZZ)-bilirubin and its photoisomers under aerobic and anaerobic conditions. The ratio of (EZ)-cyclobilirubin to (ZZ)-bilirubin increased proportionately to the dose of irradiating light and no photoequilibrium state was observed analogous to that found in configurational photoisomerization. The concentration of (EZ)- and (EE)-cyclobilirubin increased proportionately with the grade of the percentage decrease in A(460 nm) from 0 to 23%. With a percentage decrease in A(460 nm) of 23% or more, the cyclobilirubin concentrations reached a steady state. The reason for this appears to be that the concentration of (ZZ)-bilirubin, a substrate for photoisomers, dropped below 1 mg/100 mL. Biliverdin was produced only in trace amounts. However, the absorption at 520-700 nm increased after a percentage decrease in A(460 nm) of more than 23%.
Conclusions: The results of the present study show that little bilirubin photooxidation occurred with in vitro aerobic photoirradiation. Before the concentration of cyclobilirubin reaches a steady state, it is theoretically valid to use the percentage decrease in A(460 nm) for the evaluation of the clinical efficacy of the light source.
Methods: In the present study, we investigated the in vitro production pattern of bilirubin photoisomers by phototherapy light from the bilirubin-human serum albumin complex.
Results: No clear difference was found in the curves relative to (ZZ)-bilirubin and its photoisomers under aerobic and anaerobic conditions. The ratio of (EZ)-cyclobilirubin to (ZZ)-bilirubin increased proportionately to the dose of irradiating light and no photoequilibrium state was observed analogous to that found in configurational photoisomerization. The concentration of (EZ)- and (EE)-cyclobilirubin increased proportionately with the grade of the percentage decrease in A(460 nm) from 0 to 23%. With a percentage decrease in A(460 nm) of 23% or more, the cyclobilirubin concentrations reached a steady state. The reason for this appears to be that the concentration of (ZZ)-bilirubin, a substrate for photoisomers, dropped below 1 mg/100 mL. Biliverdin was produced only in trace amounts. However, the absorption at 520-700 nm increased after a percentage decrease in A(460 nm) of more than 23%.
Conclusions: The results of the present study show that little bilirubin photooxidation occurred with in vitro aerobic photoirradiation. Before the concentration of cyclobilirubin reaches a steady state, it is theoretically valid to use the percentage decrease in A(460 nm) for the evaluation of the clinical efficacy of the light source.
- リンク情報
- ID情報
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- ISSN : 1328-8067
- Web of Science ID : WOS:000176170800013