Visual assessment of jaundice in term and late preterm infants.

OBJECTIVE: To determine the accuracy of predischarge visual assessment of jaundice for estimating bilirubin concentration and predicting risk of significant neonatal hyperbilirubinaemia. DESIGN: Prospective cohort study. SETTING: Well Baby Nursery at the Hospital of the University of Pennsylvania. PATIENTS: 522 term and late preterm newborns. INTERVENTIONS: Nurses used a 5-point scale to grade the maximum cephalocaudal extent of jaundice prior to discharge. MAIN OUTCOME MEASURES: (1) Correlation between jaundice grade and bilirubin concentration. (2) Predictive accuracy of jaundice grade for identifying infants who developed significant hyperbilirubinaemia, defined as a bilirubin level that at any time after birth exceeded or was within 1 mg/dl (17 micromol/l) of the American Academy of Pediatrics-recommended hour-specific phototherapy treatment threshold. RESULTS: Nurses' assessment of jaundice extent was only moderately correlated with bilirubin concentration and was similar in black and non-black infants (Spearman's rho = 0.45 and 0.55, respectively (p = 0.13)). The correlation was particularly weak among infants <38 weeks' gestational age (rho = 0.29) compared with infants > or = 38 weeks' gestation (rho = 0.53, p = 0.05). Jaundice extent had poor overall accuracy for predicting risk of significant hyperbilirubinaemia (c-statistic = 0.65) but complete absence of jaundice had high sensitivity (95%) and excellent negative predictive value (99%) for ruling out the development of significant hyperbilirubinaemia. CONCLUSIONS: Clinicians should not use extent of cephalocaudal jaundice progression to estimate bilirubin levels during the birth hospitalisation, especially in late preterm infants. However, the complete absence of jaundice can be used to predict with very high accuracy which infants will not develop significant hyperbilirubinaemia.

Assessment of concordance among genealogical reconstructions from various mtDNA segments in three species of Pacific salmon (genus Oncorhynchus).

Seven segments of mitochondrial DNA (mtDNA), comprising 97% of the mitochondrial genome, were amplified by polymerase chain reaction (PCR) and examined for restriction site variation using 13 restriction endonucleases in three species of Pacific salmon: pink (Oncorhynchus gorbuscha), chum (O. keta) and sockeye (O. nerka) salmon. The distribution of variability across the seven mtDNA segments differed substantially among species. Little similarity in the distribution of variable restriction sites was found even between the mitochondrial genomes of the even- and odd-year broodlines of pink salmon. Significantly different levels of nucleotide diversity were detected among three groups of genes: six NADH-dehydrogenase genes had the highest; two rRNA genes had the lowest; and a group that included genes for ATPase and cytochrome oxidase subunits, the cytochrome b gene, and the control region had intermediate levels of nucleotide diversity. Genealogies of mtDNA haplotypes were reconstructed for each species, based on the variation in all mtDNA segments. The contributions of variation within different segments to resolution of the genealogical trees were compared within each species. With the exception of sockeye salmon, restriction site data from different genome segments tended to produce rather different trees (and hence rather different genealogies). In the majority of cases, genealogical information in different segments of mitochondrial genome was additive rather than congruent. This finding has a relevance to phylogeographic studies of other organisms and emphasizes the importance of not relying on a limited segment of the mtDNA genome to derive a phylogeographic structure.