PubMed · 5995286
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F Kokot. 1966-09-01. [Biochemical liver function diagnosis].. https://pubmed.ncbi.nlm.nih.gov/5995286/
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CONTEXT: Recommendations for management of jaundice in newborns presume thatjaundice is a reliable clinical finding and that the pattern and intensity of jaundice reflects the degree of elevation of the serum bilirubin level. OBJECTIVES: To determine whether experienced observers agree in describing the extent of jaundice and to evaluate the reliability of visual assessment as an indication for the measurement of serum bilirubin levels. DESIGN: Comparison of independent judgments of the extent of jaundice between examiners and with actual serum bilirubin measurements. SETTING: Well-newborn nursery in an urban public hospital. PARTICIPANTS: A convenience sample of 122 healthy term newborns whose bilirubin concentration was measured in the course of standard newborn care. Observers were experienced pediatric nurse practitioners, pediatric house staff, and pediatric attending physicians. RESULTS: Agreement was moderately good for whether an infant's skin was darkly pigmented (K = 0.56). However, agreement between observers regarding the presence of jaundice at each specific body site was poor (0%-23% agreement beyond chance); correlation between estimated bilirubin concentrations was similarly poor (Pearson correlation coefficient, 0.37). Correlation between estimated and actual bilirubin values was slightly better (Pearson correlation coefficient, 0.43-0.54). CONCLUSIONS: Clinical examination with visual assessment for jaundice in newborns is neither reliable nor accurate. The decision to perform serum bilirubin testing should be based on additional factors.
The relative steric size of methyl, methoxy, and methylthio groups was determined from circular dichroism (CD) spectroscopy using a sensitive system based on the bilirubin model. In the cyclohexane model, equatorial vs. axial orientation and conformational analysis led to quantitative measurements of orientation preference or steric demand: conformational A-values CH(3) > SCH(3) > OCH(3). A more sterically demanding model for assessing group size has been found in bilirubin analogs, which are yellow pigments that adopt a ridge-tile shape stabilized by a matrix of intramolecular hydrogen bonds. Optically active bilirubins have been shown to exhibit intense bisignate CD Cotton effects from exciton coupling of their two dipyrrinone chromophores held in either of two enantiomeric ridge-tile conformations. Interconversion of these M and P conformational enantiomers of helical chirality is rapid at room temperature but may be displaced toward either enantiomer by intramolecular nonbonded steric interactions that arise when substituents are introduced at equivalent sterically demanding sites, viz., the alpha or beta carbons of the pigment's propionic acid chains. Such substituents shift the conformational equilibrium toward the M or the P-chirality conformer, depending only on the S or R stereochemistry at the alpha and beta sites, and the resulting exciton CD for the approximately 430 nm transition(s) was used to evaluate the relative steric size, SCH(3) > CH(3) > OCH(3).
Capillary electrophoresis (CE) is a promising technique for assessment of free bilirubin and its interaction with albumin, as it requires only a small sample volume and provides a rapid and efficient separation of free bilirubin from its albumin-bound complex in a one-phase system. In order to maintain the equilibrium without dissociation of bilirubin from the albumin/bilirubin complex as in real clinical conditions, the coupling of CE with frontal analysis (FA) was investigated. A very large sample plug was introduced hydrodynamically into the capillary (36 cm length, 50 microm inner diameter) at 15 psi x s to develop the frontal conditions during CE separation. The working conditions for CE/FA separation of bilirubin and albumin were optimized as follows: +20 kV; running buffer, 10 mmol/L phosphate and 1 mmol/L ethylenediaminetetraacetic acid (EDTA), pH 7.4. The working range for bilirubin was found to vary from 5 to 206 micromol/L; precision with relative standard deviation (RSD) <2.0% for n = 3 and detection limit (signal to noise, S/N = 2) was 2 micromol/L. The residual binding capacity of a simulated cord blood serum for bilirubin was 26 mg/100 mL at pH 7.4. Bilirubin was shown to be displaced from albumin when aspirin was added. The free bilirubin concentration was found to increase to clinical significant concentrations from 11.9 to 21.1% when increasing aspirin was added in the range of 5-50 mg/100 mL, respectively. Thus, the investigation of aspirin displacement of bilirubin from albumin is clinically important and the CE/ FA method is a suitable procedure for this purpose.