Recent and changing concepts of hyperbilirubinemia and its management in the newborn

Adsorption of bilirubin by amine-containing crosslinked chitosan resins

Crosslinked chitosan resin, which has good blood compatibility, was prepared by crosslinking chitosan solution with glutaraldehyde. Polymeric adsorbents for bilirubin have been synthesized by chemical modification of crosslinked chitosan resins with di-, tri-, tetra-, and pentammines. The adsorption of bilirubin on the adsorbents was investigated in detail. The results indicated that electrostatic interaction and hydrophobic interactions are the main driving forces for the adsorption. Compared with crosslinked chitosan resin, the functionalized chitosan beads have higher adsorption capacity for unconjugated and conjugated bilirubin.

Adsorption of bilirubin with polypeptide-coated resins

Poly-L-lysine, poly-D-lysine and poly-L-ornithine have been coated covalently onto a water-swellable polyamide resin. These sorbents, especially the polylysine coated resins, exhibit high binding affinities for bilirubin in aqueous phosphate buffer solutions at 0 degrees C. The polylysine coated resins have an improved binding affinity for bilirubin over the sorbents with lysine containing oligopeptide pendants and much higher affinity than cholestyramine. The binding capacity is directly proportional to the number of lysine residues on the resin. Replacement of poly-L-lysine with poly-D-lysine does not affect the adsorption capacity.

Jaundice in full term healthy neonates--a population study

A geographically based population of 498 full term, appropriate for gestational age, healthy, singleton neonates was used to study the effect of obstetric and nursery practices on the occurrence of neonatal jaundice. At 3-4 days 56% of babies became visibly jaundiced (plasma bilirubin (PB) greater than 100 mumol/l) and 10% were hyperbilirubinaemic (PB greater than 200 mumol/l). Less mature babies, those slow to pass meconium and those who had lost weight at 4 and 7 days were more likely to be jaundiced. Obstetric practices, drugs given during labour, mother's or baby's blood group, natural illumination, plethora, extravasated blood or mode of feeding were found to have no effect. No benefit from giving supplementary milk or dextrose to breast fed babies was discovered. At 6-7 days at least 9% of babies, all but one of whom were breast fed, were visibly jaundiced. The frequency of prolonged jaundice (breast milk jaundice) was 3.8% of breast fed babies at 3 weeks and zero by 7 weeks. The proportion of babies receiving phototherapy was 2.2%.

Concerning the structure of photobilirubin II

Evidence is presented which supports the postulate that the photobilirubins IIA and IIB are diastereoisomers in which the C-3 vinyl group has cyclized intramolecularly. The evidence comes principally from proton n.m.r. spectroscopy at 400 MHz and from chemical considerations. The cyclic structures require the E-configuration at the C-4 double bond in the precursor; this is the first structural evidence for the Z leads to E isomerization in bilirubin and supports the view that the precursor (photobilirubin IA or IB) is (4E, 15Z)-bilirubin. Brief irradiation of photobilirubin II gives bilirubin, a new compound (photobilirubin III) and unchanged starting material. The various photoisomers are discussed in terms of their inter-relationships and biological fates.

Demonstration of a geometric isomer of bilirubin-IX alpha in the serum of a hyperbilirubinaemic newborn infant and the mechanism of jaundice phototherapy

Photobilirubin-IX alpha in the serum of a hyperbilirubinaemic newborn infant was demonstrated for the first time by reversed-phase high-pressure liquid chromatography. The concentrations increased significantly during phototherapy. Corresponding to these changes in the serum, biliary unconjugated bilirubin concentrations increased markedly but photobilirubin-IX alpha was not detected in the bile. Moreover, large amounts of 'unknown pigment' that are diazo-negative appeared in the bile during phototherapy.

Evidence of riboflavin depletion in breast-fed newborns and its further acceleration during treatment of hyperbilirubinemia by phototherapy

Phototherapy in the treatment of newborns with hyperbilirubinemia, resulting in degradation of bilirubin, also appears to have other photodynamic effects on metabolism. We studied flavin adenine dinucleotide (FAD) saturation of erythrocyte glutathione reductase, which should reflect riboflavin nutritional status, in 28 healthy newborns, and followed 37 newborns with hyperbilirubinemia prior to the start of and during phototherapy. The results indicate that healthy newborns on human milk feeding, relatively poor in riboflavin, have evidence of a transient riboflavin depletion soon after birth. This effect is made more pronounced by phototherapy and partially prevented by parenteral or oral administration of moderate amounts of riboflavin.