Biomedical subjects

William Hurtle

Publications and source records attributed to William Hurtle.

6 recordsLinked to original sources

PubMed2004

Exponential modeling, washout curve reconstruction, and estimation of half-life of toluene and its metabolites.

Health risks from ostensible occupational and environmental toxicant exposure are difficult to quantify. Maximal use of limited biological measurements of xenobiotic or metabolite concentration in the body is therefore essential. Elimination rates of exhaled [2H8]toluene and urinary metabolites were analyzed from 33 exposures of males to 50 ppm [2H8]toluene for 2 h at rest. It was hypothesized that the shapes from our decay curves would be applicable to any occupational or environmental toluene exposure. Except for a rapid decline in toluene blood and breath levels in the 0-0.1 h period, this "curve reconstruction" method successfully fit data from published studies. Urinary hippuric acid concentrations were not well fit due to substantial background levels, whereas o-cresol levels were accurately described. Our approach was able to reconstruct data from studies where exposure duration ranged from 10 min to 7 h, and where activity level ranged from rest to 150 W (strenuous exercise). Using this approach, limited biological data following toluene exposure could be back-extrapolated to immediate postexposure concentrations, which in turn could be compared to biological indicators of exposure to determine risk.

Adult↗

PubMed2004

Detection of the Bacillus anthracis gyrA gene by using a minor groove binder probe.

Identification of chromosomal markers for rapid detection of Bacillus anthracis is difficult because significant chromosomal homology exists among B. anthracis, Bacillus cereus, and Bacillus thuringiensis. We evaluated the bacterial gyrA gene as a potential chromosomal marker for B. anthracis. A real-time PCR assay was developed for the detection of B. anthracis. After analysis of the unique nucleotide sequence of the B. anthracis gyrA gene, a fluorescent 3' minor groove binding probe was tested with 171 organisms from 29 genera of bacteria, including 102 Bacillus strains. The assay was found to be specific for all 43 strains of B. anthracis tested. In addition, a test panel of 105 samples was analyzed to evaluate the potential diagnostic capability of the assay. The assay showed 100% specificity, demonstrating the usefulness of the gyrA gene as a specific chromosomal marker for B. anthracis.

Bacillus anthracis↗

PubMed2004

Real-time PCR assay for a unique chromosomal sequence of Bacillus anthracis.

Real-time PCR has become an important method for the rapid identification of Bacillus anthracis since the 2001 anthrax mailings. Most real-time PCR assays for B. anthracis have been developed to detect virulence genes located on the pXO1 and pXO2 plasmids. In contrast, only two published chromosomal targets exist, the rpoB gene and the gyrA gene. In the present study, subtraction-hybridization with a plasmid-cured B. anthracis tester strain and a Bacillus cereus driver was used to find a unique chromosomal sequence. By targeting this region, a real-time assay was developed with the Ruggedized Advanced Pathogen Identification Device. Further testing has revealed that the assay has 100% sensitivity and 100% specificity, with a limit of detection of 50 fg of DNA. The results of a search for sequences with homology with the BLAST program demonstrated significant alignment to the recently published B. anthracis Ames strain, while an inquiry for protein sequence similarities indicated homology with an abhydrolase from B. anthracis strain A2012. The importance of this chromosomal assay will be to verify the presence of B. anthracis independently of plasmid occurrence.

Bacillus anthracis↗

PubMed2003

Use of denaturing high-performance liquid chromatography to identify Bacillus anthracis by analysis of the 16S-23S rRNA interspacer region and gyrA gene.

Denaturing high-performance liquid chromatography (DHPLC) was evaluated as a method for identifying Bacillus anthracis by analyzing two chromosomal targets, the 16S-23S intergenic spacer region (ISR) and the gyrA gene. The 16S-23S ISR was analyzed by this method with 42 strains of B. anthracis, 36 strains of Bacillus cereus, and 12 strains of Bacillus thuringiensis; the gyrA gene was analyzed by this method with 33 strains of B. anthracis, 27 strains of B. cereus, and 9 strains of B. thuringiensis. Two blind panels of 45 samples each were analyzed to evaluate the potential diagnostic capability of this method. Our results show that DHPLC is an efficient method for the identification of B. anthracis.

Bacillus anthracis↗

PubMed2003

Detection and identification of ciprofloxacin-resistant Yersinia pestis by denaturing high-performance liquid chromatography.

Denaturing high-performance liquid chromatography (DHPLC) has been used extensively to detect genetic variation. We used this method to detect and identify Yersinia pestis KIM5 ciprofloxacin-resistant isolates by analyzing the quinolone resistance-determining region (QRDR) of the gyrase A gene. Sequencing of the Y. pestis KIM5 strain gyrA QRDR from 55 ciprofloxacin-resistant isolates revealed five mutation types. We analyzed the gyrA QRDR by DHPLC to assess its ability to detect point mutations and to determine whether DHPLC peak profile analysis could be used as a molecular fingerprint. In addition to the five mutation types found in our ciprofloxacin-resistant isolates, several mutations in the QRDR were generated by site-directed mutagenesis and analyzed to further evaluate this method for the ability to detect QRDR mutations. Furthermore, a blind panel of 42 samples was analyzed by screening for two mutant types to evaluate the potential diagnostic value of this method. Our results showed that DHPLC is an efficient method for detecting mutations in genes that confer antibiotic resistance.

Anti-Infective Agents↗

PubMed2002

Denaturing HPLC for identifying bacteria.

Denaturing HPLC (DHPLC) is used in a wide variety of genetic applications. Here we introduce a new application for this technique, the identification of bacteria. We combined the capability of DHPLC to detect sequence variation with the principles of rRNA genotyping analysis to develop a high-throughput method of identifying microorganisms. Thirty-nine bacterial species from a broad spectrum of genera were tested to determine if DHPLC could be usedfor identification. Most (36 of 39) species of bacteria had a unique peak profile that could be used as a molecular fingerprint. Furthermore, a blind panel of 65 different bacterial isolates was analyzed to demonstrate the diagnostic capability of this method to specifically identify Yersinia pestis and Bacillus anthracis. All the Y. pestis samples (10 of 10) and the majority of B. anthracis samples (12 of 14) were correctly identified. The procedure had an overall specificity of 100%, overall sensitivity of 91.7%, and a predictive value of 96.9%. The data suggest that DHPLC of products spanning regions of genetic variability will be a useful application for bacterial identification.

Bacteria↗