BackgroundRecent research suggests that diabetes, a condition whose incidence is increasing, is associated with exposure to polychlorinated biphenyls (PCBs) and chlorinated pesticides.ObjectivesWe investigated the potential association between diabetes and serum levels of PCBs, dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), and mirex in a cross-sectional study of an adult Native-American (Mohawk) population.MethodsThrough a standardized questionnaire we collected demographic, medical, and lifestyle information from 352 adults, ≥30 years of age. We collected fasting serum samples that were analyzed for 101 PCB congeners, DDE, HCB, and mirex along with fasting glucose, triglycerides, and cholesterol. Participants who had fasting-glucose values > 125 mg/dL and/or who were taking antidiabetic medication were defined as persons with diabetes. We conducted logistic regression to assess the potential association between organochlorine serum levels and diabetes, while controlling for the potential confounding variables of age, body mass index (BMI), smoking, sex, and serum lipid levels. Organochlorine serum levels were categorized in tertiles, and the lowest tertile was used as the reference category.ResultsThe prevalence of diabetes was 20.2%. The odds ratio (OR) of having diabetes for participants in the highest tertile of total PCB concentration compared with the lowest tertile was 3.9 (95% confidence interval, 1.5–10.6). The corresponding ORs for DDE and HCB were even higher. Elevated serum mirex was not associated with diabetes. After adjustment for other analytes, the OR for HCB remained significant, whereas ORs for PCBs and DDE remained elevated but not statistically significant. In contrast, after adjustment for other analytes, the OR for mirex became statistically significant and indicated an inverse association.ConclusionsIn this study of adult Native Americans, elevated serum PCBs, DDE, and HCB were positively associated with diabetes after controlling for potential confounders, whereas a negative association was observed for mirex.

We have investigated the relationships among the concentration of total serum polychlorinated biphenyls (PCBs), various PCB congener groupings, and three pesticides to total serum lipids in humans with and without self-reported cardiovascular disease. Blood samples were obtained from 335 adult Akwesasne Mohawks, and were analyzed for 101 PCB congeners, mirex, DDE, and hexachlorobenzene (HCB), as well as serum triglycerides and cholesterol. Structural equation modeling, following the definition of latent variables by means of confirmatory factor analysis, was used to analyze the relationships between serum lipids with PCBs and heart disease. There were significant associations among PCBs, lipids, age, and body mass index (BMI), a fact which justified the application of the structural equation model. Gender of the participant was unrelated to any of the remaining study variables. The results of this study are consistent with a model in which age is considered as both an exogenous explanatory variable and a biological driving mechanism for the acquisition of PCBs. Moreover, the results of this study are consistent with the conclusion that PCBs, acting through P450 enzymes, are directly responsible for increased synthesis of cholesterol and triglycerides, substances known to be major risk factors for cardiovascular disease.

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Fifteen children with infantile spasms and a hypsarrhythmic EEG defined by EEG-videotelemetry monitoring received a regimen of high-dose (150 IU/m2/d) ACTH for their seizures. We carried out an endocrinologic evaluation before and after initiation of the ACTH and conducted a time course study of plasma ACTH and cortisol levels after ACTH dosing. Spasms were controlled and the EEG normalized in 14 of the 15 children. Prior to starting ACTH therapy all the patients had normal prolactin, insulin, cortisol, and ACTH levels in plasma and normal thyroid function. Although the pattern of rise of ACTH levels in plasma after ACTH dosing was similar in all the children, there was great individual variation in the absolute concentrations. However, both the pattern of rise and absolute level of cortisol in plasma after ACTH was highly predictable in all patients. Plasma cortisol rose rapidly within 1 hour of ACTH administration and continued a slower rise for 12 to 24 hours after the ACTH dose. High-dose ACTH therapy seems quite effective in infantile spasms, perhaps because of a sustained high level of plasma cortisol. This sustained plateau of cortisol may be more effective in controlling infantile spasms than the pulse effect expected with oral steroids or lower doses of ACTH.

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Aspartate aminotransferase (EC 2.6.1.1) activity and the distribution of its isoenzymes in human liver were examined. Rabbit antiserum against porcin soluble (i.e., non-mitochondrial) enzyme cross-reacted with the soluble enzyme of human origin and was used in an immunoprecipitation assay to quantitate the soluble and mitochondrial isoenzymes. These were separated by rapid, semiquantitative electrophoresis on cellulose acetate and by three other quantitative techniques: isoelectric focusing and anion-and cation-exchange chromatography. The mitochrondrial enzyme averaged 81% of the total activity in normal adult human liver (n = 4). Its contribution was dramatically reduced in single specimens of human fetal liver (56% of total activity) and hepatoblastoma tissue (38%). Total enzyme activities (mumol min-1 per gram of tissue) were: adult, 150; fetal, 38; tumor, 6. Total enzyme concentrations (micromoles of enzyme per kilogram of tissue) found were: adult, 10.8; fetal, 2.7; tumor, 0.4. The concentrations and isoenzyme distribution in human liver are compared to those in various animal model systems. Other methods for quantitative estimation of the isoenzymes and their adaptability for use in estimating concentrations in serum are reviewed.

In addition to hormones, the serum constituents affected by stripping are certain vitamins, electrolytes, enzyme activities, and metabolites.

Commutability is a property of a reference material (RM) that relates to the closeness of agreement between results for an RM and results for clinical samples (CSs) when measured by ≥ 2 measurement procedures (MPs). Commutability of RMs used in a calibration traceability scheme is an essential property for them to be fit for purpose. Similarly, commutability of trueness controls or external quality assessment samples is essential when those materials are used to assess trueness of results for CSs. This report is part 1 of a 3-part series describing how to assess commutability of RMs. Part 1 defines commutability and addresses critical components of the experimental design for commutability assessment, including selection of individual CSs, use of pooled CSs, qualification of MPs for inclusion, establishing criteria for the determination that an RM is commutable, generalization of commutability conclusions to future measurements made with the MPs included in the assessment, and information regarding commutability to be included in the certificate for an RM. Parts 2 and 3 in the series present 2 different statistical approaches to commutability assessment that use fixed criteria related to the medical decisions that will be made using the laboratory test results.