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Objectives: Identifying common clinical and environmental factors that influence newborn metabolic biomarkers will improve the utilization of metabolite panels for clinical diagnostic medicine., Design and Methods: Environmental effects including gender, season of birth, gestational age, birth weight, feeding method and age at time of collection were evaluated for over 50 metabolites collected by the Iowa Neonatal Metabolic Screening Program on 221,788 newborns over a six year period., Results: We replicated well known observations that low birth weight and preterm infants have higher essential amino acids and lower medium and long chain acylcarnitine levels than their term counterparts. Smaller, but still significant, differences were observed for gender and timing of sample collection, specifically the season in which the infant was born. Most intriguing were our findings of higher thyroid stimulating hormone in the winter months (P<1×10(-40)) which correlated with an increased false positive rate of congenital hypothyroidism in the winter (0.9%) compared to summer (0.6%). Previous studies, conducted globally, have identified an increased prevalence of suspected and confirmed cases of congenital hypothyroidism in the winter months. We found that the percentage of unresolved suspected cases were slightly higher in the winter (0.3% vs. 0.2%)., Conclusions: We identified differences in metabolites by gestational age, birth weight, gender and season. Some are widely reported such as gestational age and birth weight, while others such as the effect of seasonality are not as well studied., (Copyright © 2012 The Canadian Society of Clinical Chemists. All rights reserved.)

Detergent-solubilized hepatic microsomal fractions from alloxan diabetic rats exhibited a 52,000 molecular weight hemeprotein band that was not present in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) protein profiles of identically solubilized hepatic microsomal fractions from normal, 3-methylcholanthrene- or phenobarbital-treated rats. This 52,000 mol. wt hemeprotein band disappeared from the protein profile of insulin-treated diabetic rat liver to yield the SDS-PAGE profile of normal rat liver. When P-450 hemeproteins were purified by lauric acid affinity and hydroxylapatite chromatography from solubilized microsomes, only the diabetic rat had a 52,000 mol. wt P-450. This distinct 52,000 mol. wt diabetes-induced P-450 interacted with type II compounds to yield a 2-fold greater absorbance change than was observed with the purified P-450s from either the normal or the chemically induced rats. The properties of this unique 52,000 mol. wt P-450 suggest that it may be the catalytic component responsible for the increased rate of type II substrate (aniline) metabolism observed in the diabetic rat.

1. Glucagon stimulated gluconeogenesis from both [U-14C]lactate and [14C]xylitol in isolated perfused mouse liver. 2. Addition of cyclic AMP also stimulated gluconeogenesis from [U-14C]lactate. 3. Glucagon caused a rapid (2.5 min) 12-fold increase in hepatic cyclic AMP but not cyclic GMP concentration. 4. Glucagon caused a rapid and stable decrease in hepatic fructose 1,6-diphosphatase activity measured in vitro. 5. The results are interpreted to indicate that glucagon stimulates hepatic gluconeogenesis in mice via cyclic AMP by two different mechanisms: (a) increased substrate uptake (i.e. utilization) and (b) increased gluconeogenic efficiency (i.e. inhibition of alternate substrate fates).