Detection and Quantification of Organophosphate Pesticides in Human Serum

The United States Environmental Agency permits the use of 39 organophosphate pesticides. Many of these pesticides are acutely toxic and have lasting effect on human health. Organophosphates quickly metabolize in the body, therefore currently human exposure is studied by measuring the metabolic products in urine. In this work a suite of analytical methods was developed to determine the presence of un-metabolized organophosphate pesticides in human serum. First mass spectroscopic detection methods were evaluated. Gas chromatograph coupled tandem mass spectrometer was used to compare the detection limits using chemical and electron impact ionization. Positive chemical ionization was selected, because it provided better detection limits for this set of analytes. Liquid chromatograph coupled tandem mass spectrometry was also evaluated and was found advantageous over the gas chromatographic method for approximately 50% of the compounds. Positive atmospheric pressure chemical ionization was chosen for this group of compounds. Once the analytes were separated by detection methods, analytical separation methods were compared: column and eluent was selected for liquid chromatography, column alone was selected for gas chromatography. Last step of the method development was to produce a suitable sample cleanup process. Solid phase extraction was not suitable because the very wide range of solubility characteristics and hydrolytic stability of the analytes. Lyophilization, liquid-liquid extraction methods were tested and compared. A multi step cleanup method was produced, which starts with liquid-liquid extraction using high pressure ethyl acetate in accelerated solvent extractor, solvent exchange and a lipid removal step. The concentrated extract then injected in a HPLC-MS-MS system then the same extract either directly injected in GC-MS-MS or further purified using headspace solid phase micro extraction before the GC-NS-MS step. The method was used with good results for analyzing samples collected from farm workers using OP pesticides

Polyfluoroalkyl Chemicals in the U.S. Population: Data from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 and Comparisons with NHANES 1999–2000

BACKGROUND: Polyfluoroalkyl chemicals (PFCs) have been used since the 1950s in numerous commercial applications. Exposure of the general U.S. population to PFCs is widespread. Since 2002, the manufacturing practices for PFCs in the United States have changed considerably. OBJECTIVES: We aimed to assess exposure to perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and eight other PFCs in a representative 2003–2004 sample of the general U.S. population ≥ 12 years of age and to determine whether serum concentrations have changed since the 1999–2000 National Health and Nutrition Examination Survey (NHANES). METHODS: By using automated solid-phase extraction coupled to isotope dilution–high-performance liquid chromatography–tandem mass spectrometry, we analyzed 2,094 serum samples collected from NHANES 2003–2004 participants

Association Among Serum Perfluoroalkyl Chemicals, Glucose Homeostasis, and Metabolic Syndrome in Adolescents and Adults

OBJECTIVE - Perfluoroalkyl chemicals (PFCs) have been used worldwide in a variety of consumer products. The effect of PFCs on glucose homeostasis is not known. RESEARCH DESIGN AND METHODS - We examined 474 adolescents and 969 adults with reliable serum measures of metabolic syndrome profile from the National Health and Nutrition Examination Survey 1999-2000 and 2003-2004. RESULTS - In adolescents, increased serum perfluorononanoic acid (PFNA) concentrations were associated with hyperglycemia (odds ratio [OR] 3.16 [95% Cl 1.39-7.16], P < 0.05). Increased serum PFNA concentrations also have favorable associations with serum HDL cholesterol (0.67 [0.45-0.99], P < 0.05). Overall, increased serum PFNA concentrations were inversely correlated with the prevalence of the metabolic syndrome (0.37 [0.21-0.64], P < 0.005). In adults, increased serum perfluorooctanoic acid concentrations were significantly associated with increased beta-cell function (beta coefficient 0.07 +/- 0.03, P < 0. 05 ). Increased serum perfluorooctane sulfate (PFOS) concentrations were associated with increased blood insulin (0.14 +/- 0.05, P < 0.01), homeostasis model assessment of insulin resistance (0.14 0.05, P < 0.01), and beta-cell function (0.15 +/- 0.05, P < 0.01). Serum PFOS concentrations were also unfavorably correlated with serum HDL cholesterol (OR 1.61 [95% Cl 1.15-2.26], P < 0.05). CONCLUSIONS - Serum PFCs were associated with glucose homeostasis and indicators of metabolic syndrome. Further clinical and animal studies are warranted to clarify putative causal relationships

Effect of the ABCA1 agonist CS-6253 on amyloid-beta and lipoprotein metabolism in cynomolgus monkeys

BACKGROUND: Inducing brain ATP-binding cassette 1 (ABCA1) activity in Alzheimer's disease (AD) mouse models is associated with improvement in AD pathology. The purpose of this study was to investigate the effects of the ABCA1 agonist peptide CS-6253 on amyloid-β peptides (Aβ) and lipoproteins in plasma and cerebrospinal fluid (CSF) of cynomolgus monkeys, a species with amyloid and lipoprotein metabolism similar to humans. METHODS: CS-6253 peptide was injected intravenously into cynomolgus monkeys at various doses in three different studies. Plasma and CSF samples were collected at several time points before and after treatment. Levels of cholesterol, triglyceride (TG), lipoprotein particles, apolipoproteins, and Aβ were measured using ELISA, ion-mobility analysis, and asymmetric-flow field-flow fractionation (AF4). The relationship between the change in levels of these biomarkers was analyzed using multiple linear regression models and linear mixed-effects models. RESULTS: Following CS-6253 intravenous injection, within minutes, small plasma high-density lipoprotein (HDL) particles were increased. In two independent experiments, plasma TG, apolipoprotein E (apoE), and Aβ42/40 ratio were transiently increased following CS-6253 intravenous injection. This change was associated with a non-significant decrease in CSF Aβ42. Both plasma total cholesterol and HDL-cholesterol levels were reduced following treatment. AF4 fractionation revealed that CS-6253 treatment displaced apoE from HDL to intermediate-density- and low density-lipoprotein (IDL/LDL)-sized particles in plasma. In contrast to plasma, CS-6253 had no effect on the assessed CSF apolipoproteins or lipids. CONCLUSIONS: Treatment with the ABCA1 agonist CS-6253 appears to favor Aβ clearance from the brain

Raman spectroscopic detection of the T-HgII-T base pair and the ionic characteristics of mercury

Developing applications for metal-mediated base pairs (metallo-base-pair) has recently become a high-priority area in nucleic acid research, and physicochemical analyses are important for designing and fine-tuning molecular devices using metallo-base-pairs. In this study, we characterized the HgII-mediated T-T (T-HgII-T) base pair by Raman spectroscopy, which revealed the unique physical and chemical properties of HgII. A characteristic Raman marker band at 1586 cm−1 was observed and assigned to the C4=O4 stretching mode. We confirmed the assignment by the isotopic shift (18O-labeling at O4) and density functional theory (DFT) calculations. The unusually low wavenumber of the C4=O4 stretching suggested that the bond order of the C4=O4 bond reduced from its canonical value. This reduction of the bond order can be explained if the enolate-like structure (N3=C4-O4−) is involved as a resonance contributor in the thymine ring of the T-HgII-T pair. This resonance includes the N-HgII-bonded state (HgII-N3-C4=O4) and the N-HgII-dissociated state (HgII+ N3=C4-O4−), and the latter contributor reduced the bond order of N-HgII. Consequently, the HgII nucleus in the T-HgII-T pair exhibited a cationic character. Natural bond orbital (NBO) analysis supports the interpretations of the Raman experiments