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Biomedical subjects

S E Baker

Publications and source records attributed to S E Baker.

28 records · Page 2Linked to original sources
PubMed1995

Determination of pesticide metabolites in human urine using an isotope dilution technique and tandem mass spectrometry.

A method that measures 12 analytes in urine and reflects possible exposure to pesticides was developed. The sample preparation involves enzyme hydrolysis and solvent extraction through the use of laboratory robotics, followed by phase-transfer catalysis derivatization and silica cleanup. Samples are analyzed by capillary gas chromatography and tandem mass spectrometry using an isotope dilution technique with 13C-labeled internal standards. The limit of detection is 1 microgram/L (1 part per billion) for most analytes, and most analytes have a linear response up to 100 micrograms/L. The precision of the method is reflected in the variation observed in quality control materials over 33 months; the variation averaged 17% for these analytes. On the basis of the detectable analyte levels of unspiked urine samples collected from unexposed volunteers, this method can be used to measure the low levels necessary for establishing reference range values of the selected pesticides or metabolites.

Calibration↗
PubMed1995

Murine cytomegalovirus-associated arteritis.

Unique inflammatory lesions affecting the ascending aorta and pulmonary artery of BALB/c and C57BL/6 mice infected with murine cytomegalovirus (MCMV) were identified in a pilot and two subsequent experiments to characterize the potential effect of MCMV infection on diet-induced atherosclerotic lesions. Suckling BALB/c and C57BL/6 mice were inoculated with MCMV and subsequently fed either a commercial mouse diet or a synthetic atherogenic diet from weaning. The three experiments varied with respect to the age of the mice at the time of MCMV inoculation and the dose of virus given. The conditions of MCMV exposure were progressively modified in the three experiments to increase the prevalence of MCMV-associated inflammatory lesions in the pulmonary artery and aorta. In the final experiment, in which suckling mice were inoculated at 9 days of age, MCMV-associated arteritic lesions had an observed prevalence at 8 weeks post-inoculation of 87.5% (7/8) in BALB/c mice on the normal diet and 100% (8/8) in C57BL/6 mice on the normal diet and in both strains on the atherogenic diet. The inflammatory lesions in both vessels were characterized by mononuclear cell infiltrates containing CD3+, CD4+, and CD8+ lymphocytes. The cellular infiltrates were often more intense on the adventitial surface and infiltrated into the overlying tunica media. The intima was infiltrated by mononuclear cell infiltrates that appeared to contain more macrophages and fewer lymphocytes than did the adventitial infiltrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMedDate not supplied

Quantification of selected pesticide metabolites in human urine using isotope dilution high-performance liquid chromatography/tandem mass spectrometry.

The annual domestic use of pesticides is continually increasing, virtually ensuring that everyone is exposed to some level of pesticides on a regular basis through diet or environment. The potential developmental and physical adverse effects these chronic pesticide exposures have on children are of increasing concern. To adequately evaluate the potential adverse effects resulting from these exposures, accurate methods to measure the amount of the pesticide absorbed by the body must be developed. We have developed a sensitive method to measure the urinary metabolites of atrazine, diazinon, malathion, 2,4-dichlorophenoxyacetic acid (2,4-D), and certain synthetic pyrethroids in human urine. In our method, stable isotopically labeled analogues of the metabolites were spiked into the urine, which was subsequently extracted at both a neutral and acidic pH using organic solvents. The extracts were analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) using atmospheric pressure chemical ionization. Our method has limits of detection ranging from 20 to 500 ng/l (parts per trillion) and relative standard deviations of less than 11%. This method has been used to measure the internal doses of these pesticides in both adults and children (n = 130) with no documented exposure to the pesticides. We detected atrazine and synthetic pyrethroid metabolites in less than 12% of the samples analyzed. The metabolites of 2,4-D, malathion, and diazinon were detected in 22%, 32%, and 57% of the samples, respectively.

Adult↗