Robert Rej

Diabetes in relation to serum levels of polychlorinated biphenyls and chlorinated pesticides in adult Native Americans.

Background Recent research suggests that diabetes, a condition whose incidence is increasing, is associated with exposure to polychlorinated biphenyls (PCBs) and chlorinated pesticides. Objectives We 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. Methods Through 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. Results The 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. Conclusions In 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.

Lower Serum Testosterone Associated with Elevated Polychlorinated Biphenyl Concentrations in Native American Men

Background Polychlorinated biphenyls (PCBs) and chlorinated pesticides are endocrine disruptors, altering both thyroid and estrogen hormonal systems. Less is known of action on androgenic systems. Objective We studied the relationship between serum concentrations of testosterone in relation to levels of PCBs and three chlorinated pesticides in an adult Native American (Mohawk) population. Methods We collected fasting serum samples from 703 adult Mohawks (257 men and 436 women) and analyzed samples for 101 PCB congeners, hexachlorobenzene (HCB), dichlorodiphenyldichloroethylene (DDE), and mirex, as well as testosterone, cholesterol, and triglycerides. The associations between testosterone and tertiles of serum organochlorine levels (both wet weight and lipid adjusted) were assessed using a logistic regression model while controlling for age, body mass index (BMI), and other analytes, with the lowest tertile being considered the referent. Males and females were considered separately. Results Testosterone concentrations in males were inversely correlated with total PCB concentration, whether using wet-weight or lipid-adjusted values. The odds ratio (OR) of having a testosterone concentration above the median was 0.17 [95% confidence interval (CI), 0.05–0.69] for total wet-weight PCBs (highest vs. lowest tertile) after adjustment for age, BMI, total serum lipids, and three pesticides. The OR for lipid-adjusted total PCB concentration was 0.23 (95% CI, 0.06–0.78) after adjustment for other analytes. Testosterone levels were significantly and inversely related to concentrations of PCBs 74, 99, 153, and 206, but not PCBs 52, 105, 118, 138, 170, 180, 201, or 203. Testosterone concentrations in females are much lower than in males, and not significantly related to serum PCBs. HCB, DDE, and mirex were not associated with testosterone concentration in either men or women. Conclusions Elevation in serum PCB levels is associated with a lower concentration of serum testosterone in Native American men.

Effects of Resin or Charcoal Treatment on Fetal Bovine Serum and Bovine Calf Serum

Introduction. Charcoal- or resin-stripping of fetal bovine serum (FBS) or bovine calf serum (BCS) intended for supplementation of cell culture media is widely practiced to remove a variety of endogenous compounds, including steroid, peptide, and thyroid hormones. The possibility that stripping removes other biologically relevant factors from serum may not be appreciated. Methods. In this report, standardized clinical laboratory testing methods were used to assess the effects of resin- and charcoal-stripping on content in FBS and BCS of more than 25 analytes in the sera. Results and Conclusion. In addition to hormones, the serum constituents affected by stripping are certain vitamins, electrolytes, enzyme activities, and metabolites.

Interference by Tris buffer in the estimation of protein by the Lowry procedure

Abstract Tris buffers were found to distort the measurement of protein by the Lowry method both by decreasing chromophore development with protein and by contributing blank color. Tris at an assay concentration of 0.37 m m markedly affects measured results. Similar Tris effects were observed at all wavelengths between 450 and 800 nm and with diverse protein samples. The distortion due to Tris is not correctable by simple blank correction, but it can be overcome by incorporating the same amount of Tris in the standards used. The distortion at Tris concentrations m appears to be within tolerable limits. No interference or distortion was observed with sodium phosphate buffer to an assay concentration of 40 m m . An automated Lowry procedure is also presented which gives excellent correlation with the manual method and an average coefficient of variation of

Quality control in clinical chemistry: characterization of reference materials.

Reference serum preparations are key components of internal and external quality-control programmes. These materials are often poorly characterized, and use of inappropriate specimens may result in erroneous conclusions regarding quality of laboratory data. Several techniques are described that characterize specimens used in the quality-control or calibration of laboratory procedures. A characteristic approach requires detailed study of a few fundamental characteristics of reference preparations-such as steady-state kinetic properties of an enzyme-and comparison with the same parameters determined for patient specimens. Descriptive techniques-ratio methods and the multivariate statistical procedure of correspondence analysis-are used for further description of the interactions of materials in a variety of assay methods. The applications of these procedures to two clinical analytes-theophylline and alkaline phosphatase-are described.

Acute toxicity in guinea pigs and rabbits of soot from a polychlorinated biphenyl-containing transformer fire

Abstract A fire involving a polychlorinated biphenyl (PCB)-containing transformer extensively contaminated the State Office Building in Binghamton, New York, with a sootlike material containing 2,3,7,8-tetrachlorodibenzo- p -dioxin (2,3,7,8-TCDD), 2,3,7,8-tetrachlorodibenzofuran, and high concentrations of numerous other polychlorinated dibenzodioxins, dibenzofurans, and PCBs. The oral LD50s of the soot and of its benzene extract, each administered to female guinea pigs in 0.75% aqueous methyl cellulose, were 410 mg of soot/kg and 327 mg of soot equivalent/kg, respectively. Serum triglycerides were elevated in males at 100 and 500 mg/kg and in females at 500 mg/kg. Alkaline phosphatase was lowered in females at 500 mg/kg. Histopathology revealed dose-related pancreatic duct hyperplasia and salivary gland duct metaplasia in males. Body weight loss was observed in both sexes at 500 mg/kg. Thymus weight decreased in both sexes at 100 and 500 mg/kg, and kidney weights decreased in males at these doses. Dermal application of soot to rabbits for 24 hr caused no overt toxicity, although hepatic centrilobular hypertrophy was observed in both sexes. Similar application of soot extract caused a local serous inflammation in addition to the hepatic centrilobular hypertrophy. The oral LD50 for 2,3,7,8-TCDD in female guinea pigs was 19 μg/kg in aqueous methyl cellulose and 2.5 μg/kg in corn oil. We concluded that the soot matrix alters the dermal but not the oral toxicity of its components, that the toxic effects were consistent with those reported after exposure to dibenzodioxins and dibenzofurans, and the aqueous vehicle markedly diminished the acute toxicity of 2,3,7,8-TCDD relative to that in corn oil vehicle.

Transferrin and mitochondrial aspartate aminotransferase in young adult alcoholics

Two recently proposed biochemical markers of alcoholism, namely, quantitation of plasma transferrin variant (Tf5.7) and the ratio of plasma mitochondrial aspartate aminotransferase (m-AspAT) to total AspAT (t-AspAT), were tested for their ability to detect young adult alcoholics. Another commonly used biochemical test, namely, activity of plasma gamma glutamyltransferase (GGT) was included as a comparison. Although mean values of GGT, TF5.7, total transferrin (Tftot), m-AspAT and t-AspAT in alcoholics were significantly higher than those in controls, there were too many overlapping values in each test between alcoholics and controls to render any of these tests suitable as a marker for young adult alcoholics. Depending on cut-off limits, the sensitivity of each test ranged from 0-52% and the specificity ranged from 80-97%. Moreover, the m-AspAT/t-AspAT and Tf5.7/Tftot ratios were not significantly different between alcoholics and controls. A stepwise linear discriminant function analysis of all the variables resulted in a slight increase in classification sensitivity (66%) but a decrease in specificity (77%). The relatively short duration (mean = 5.6 years) of heavy alcohol intake and the time elapsed (mean = 5.8 days) since the alcoholics last consumed alcohol very likely contributed to the low sensitivity. Young adults might also be more resilient with regard to the damaging biochemical effects of ethanol. Abnormal biochemical values might reverse to normal values much more quickly in young adult alcoholics than in those who are older and have more years of alcohol abuse.

A Convenient Continuous -Rate Spectrophotometric Method for Determination of Amino Acid Substrate Specificity of Aminotransferases: Application to Isoenzymes of Aspartate Aminotransferase

Abstract A continuous-rate spectrophotometric procedure is presented for determination of the amino acid substrate specificity of 2-oxoglutarate-dependent aminotransferases. The reaction utilizes a glutamate dehydrogenase- and diaphorase-coupled enzyme system; the rate of formazan dye produced is related to enzyme activity at 500 nm. Of 20 amino acids examined with this assay, only l -aspartate and l -glutamate were found to be substrates for human and porcine cytosolic aspartate aminotransferase (EC 2.6.1.1). l -Tyrosine was found to be a significant substrate for the human liver mitochondrial enzyme.

Standardization of high-sensitivity immunoassays for measurement of C-reactive protein; II: Two approaches for assessing commutability of a reference material.

BACKGROUND We evaluated the commutability of a proposed reference material (PRM), with a formulation based on dilution of Certified Reference Material 470 (CRM470), for 24 high-sensitivity C-reactive protein (hsCRP) methods. We also investigated whether calibration by use of PRM was effective in harmonizing results. METHODS A set of 40 native clinical samples was measured along with PRM and 3 dilutions of PRM. We used weighted least-squares polynomial regression (WLS/PR) to perform comparisons between all method combinations and to calculate normalized residuals for the PRM. The PRM was considered noncommutable if any of the normalized residuals for a method pair was >2. Correspondence analysis (CA) was used to explore the multidimensional relationships between methods and samples to evaluate if the PRM had properties similar to native clinical samples. Clinical sample results from the methods for which PRM was commutable were recalibrated based on the PRM results, and ANOVA was used to estimate the CVs before and after recalibration. RESULTS After omitting data for 9 methods because of poor precision or procedural flaws, we used data from the 15 remaining methods to evaluate commutability. Using both WLS/PR and CA we found that PRM was noncommutable with 1 method. We found modest improvement in total and among-method CVs when PRM was used to harmonize the results from the 14 methods for which it was commutable. CONCLUSIONS A PRM with a formulation based on dilution of CRM470 was commutable with native clinical samples for 14 of 15 hsCRP methods that had acceptable precision. For those methods the use of PRM may contribute to improved harmonization of results for native clinical samples.

Subchronic exposure of mice to Love Canal soil contaminants.

The health hazard potential of soil collected from the surface of the Love Canal chemical dump site in Niagara Falls, New York, was assessed in 90-day exposure studies. Female CD-1 mice were exposed to two concentrations of the volatile components of 1 kg of soil with and without direct soil contact. Control mice were identically housed but without soil. The soil was replaced weekly and 87 compounds were detected in the air in the cages above fresh and 7-day-old soil as analyzed by gas chromatography/mass spectrometry. The concentration of many of these compounds decreased during the 7-day exposure cycle. Histopathologic, hematologic, and serum enzyme studies followed necropsy of all mice. There was no mortality of mice exposed for up to 90 days under any condition. Thymus and spleen weights relative to body weight were increased after 4 weeks of exposure by inhalation but not after 8 or 12 weeks of exposure. alpha-, beta-, and delta- Benzenehexachlorides , pentachlorobenzene, and hexachlorobenzene were detected in liver tissue from these animals. Mice exposed to 5- to 10-fold elevated concentration of volatiles had increased body and relative kidney weights. There was no chemically induced lesion in any animal exposed only to the volatile soil contaminants. Mice exposed by direct contact with the soil without elevated volatile exposure had increased body (10%) and relative liver weights (169%). Centrolobular hepatocyte hypertrophy, which involved 40 to 70% of the lobules, was observed in all mice in this group.(ABSTRACT TRUNCATED AT 250 WORDS)