Comparison of the bilirubin concentration and the bilirubin/albumin ratio with the bilirubin-binding ability in neonatal serum

Robertson, Alex; Karp, Warren B.; Brodersen, Rolf

doi:10.1016/s0022-3476(98)70457-3

Cited by 7 publications

(1 citation statement)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Serum albumin concentrations in the early neonatal period are dependent on gestational age, varying from a mean of 1.9 g/dl before 30 wk gestation to 3.1 g/dl at term (9). One study revealed a mean serum albumin level of 2.5 g/dl (range: 0.8-4.0 g/dl) for infants with gestational ages ranging from 26 to 42 wk (mean: 33 wk) admitted to the neonatal intensive care unit (33). Although serum levels of apo D also appear to correlate with gestational age, variations are much less pronounced compared with albumin, with a mean value of 3.7 Ϯ 1.4 mg/dl at birth (22).…”

Section: Discussionmentioning

confidence: 99%

Role of apolipoprotein D in the transport of bilirubin in plasma

Goessling

Zucker

2000

American Journal of Physiology-Gastrointestinal and Liver Physi

View full text Add to dashboard Cite

Apolipoprotein D (apo D) is a 30-kDa glycoprotein of unknown function that is associated with high-density lipoproteins (HDL). Because unconjugated bilirubin has been shown to bind apo D with a 0. 8:1 stoichiometry, we examined the contribution of this protein to transport of bilirubin in human plasma. Density gradient centrifugation analysis using physiological concentrations of [(14)C]bilirubin reveals that 9% of unconjugated bilirubin is associated with HDL, with the remaining pigment bound primarily to serum proteins (i.e., albumin). The percentage of total plasma bilirubin bound to HDL was found to increase proportionally with bilirubin concentration. Affinity of human apo D for bilirubin was determined by steady-state fluorescence quenching, with Scatchard analysis demonstrating a single binding site for unconjugated bilirubin with an affinity constant (K(a)) of approximately 3 x 10(7) M(-1). Incorporation of apo D into phosphatidylcholine vesicles had no effect on K(a), suggesting that a lipid environment does not alter the affinity of the protein for bilirubin. Using stopped-flow techniques, the first-order rate constant for bilirubin dissociation from apo D was measured at 5.4 s(-1) (half-time = 129 ms). Our findings indicate that HDL is the principal nonalbumin carrier of bilirubin in human plasma and further support the proposition that the affinity of HDL for bilirubin is primarily the result of binding to apo D.

show abstract

Section: Discussionmentioning

confidence: 99%