Biomedical subjects

Ajaib Singh

Publications and source records attributed to Ajaib Singh.

5 recordsLinked to original sources

PubMed2005

Development of procedures for direct extraction of Cryptosporidium DNA from water concentrates and for relief of PCR inhibitors.

Extraction of high-quality DNA is a key step in PCR detection of Cryptosporidium and other pathogens in environmental samples. Currently, Cryptosporidium oocysts in water samples have to be purified from water concentrates before DNA is extracted. This study compared the effectiveness of six DNA extraction methods (DNA extraction with the QIAamp DNA minikit after oocyst purification with immunomagnetic separation and direct DNA extraction methods using the FastDNA SPIN kit for soil, QIAamp DNA stool minikit, UltraClean soil kit, or QIAamp DNA minikit and the traditional phenol-chloroform technique) for the detection of Cryptosporidium with oocyst-seeded samples, DNA-spiked samples, and field water samples. The study also evaluated the effects of different PCR facilitators (nonacetylated bovine serum albumin, the T4 gene 32 protein, and polyvinylpyrrolidone) and treatments (the use of GeneReleaser or ultrafiltration) for the relief from or removal of inhibitors of PCR amplification. The results of seeding and spiking studies showed that PCR inhibitors were presented in all DNA solutions extracted by the six methods. However, the effect of PCR inhibitors could be relieved significantly by the addition of 400 ng of bovine serum albumin/mul or 25 ng of T4 gene 32 protein/mul to the PCR mixture. With the inclusion of bovine serum albumin in the PCR mixture, DNA extracted with the FastDNA SPIN kit for soil without oocyst isolation resulted in PCR performance similar to that produced by the QIAamp DNA minikit after oocysts were purified by immunomagnetic separation.

Animals↗

PubMed2004

Distribution of Giardia duodenalis genotypes and subgenotypes in raw urban wastewater in Milwaukee, Wisconsin.

Giardia cysts in 131 raw wastewater samples from Milwaukee, Wis., were genotyped by sequence analysis of the triosephosphate isomerase gene which showed the presence of two distinct genotypes (assemblages A and B) of Giardia duodenalis. Of the 131 samples, 111 belonged to assemblage A, and the remaining samples belonged to assemblage B. A high degree of genetic polymorphism was evident within the assemblage B cluster, with 10 distinct subgenotypes identified, eight of which have not been reported before.

Animals↗

PubMed2004

Decision analysis: point-of-care Chlamydia testing vs. laboratory-based methods.

OBJECTIVE: To evaluate and compare the performance of several different methods available for detection of Chlamydia trachomatis (Ct) infection, and to explore possible testing and treatment strategies incorporating point-of-care testing versus laboratory-based tests. DESIGN: Prospective trial and decision analysis. SETTING: Large, urban, publicly funded sexually transmitted disease clinic. PARTICIPANTS: 1,384 female patients. METHODS: Each subject was tested for Ct infection by direct fluorescent antibody (DFA, Sanofi/Kallestad, Chaska, MN), optical immunoassay (OIA, Thermo Electron, Point of Care and Rapid Diagnostics, Louisville CO), McCoy cell culture (in-house method), and polymerase chain reaction (microwell PCR, microwell assay, Roche, Branchburg NJ). RESULTS: Performing a rapid in-clinic test on women who did not meet empiric treatment criteria would have increased the overall proportion of infected persons receiving same-day treatment from 48.6% to 79.1% using DFA or 78.4% using OIA. CONCLUSIONS: Use of empiric treatment criteria and same-day point-of-care testing for patients not meeting the empiric treatment threshold appears to be an appropriate, useful, and cost-effective strategy for increasing same-day treatment of Ct infections in this population.

Adolescent↗

PubMed2004

Non-point source pollution: determination of replication versus persistence of Escherichia coli in surface water and sediments with correlation of levels to readily measurable environmental parameters.

Racine, Wisconsin, located on Lake Michigan, experiences frequent recreational water quality advisories in the absence of any identifiable point source of pollution. This research examines the environmental distribution of Escherichia coli in conjunction with the assessment of additional parameters (rainfall, turbidity, wave height, wind direction, wind speed and algal presence) in order to determine the most probable factors that influence E. coli levels in surface waters. Densities of E. coli were highest in core samples taken from foreshore sands, often exceeding an order of magnitude greater than those collected from submerged sands and water. Simple regression and multivariate analyses conducted on supplementary environmental data indicate that the previous day's E. coli concentration in conjunction with wave height is significantly predictive for present-time E. coli concentration. Genetic fingerprinting using repetitive element anchored PCR and cellular fatty acid analysis were employed to assess the presence of clonal isolates which indicate replication from a common parent cell. There were relatively few occurrences of clonal patterns in isolates collected from water, foreshore and submerged sands, suggesting that accumulation of E. coli, rather than environmental replication, was occurring in this system. Non-point source pollution, namely transport of accumulated E. coli from foreshore sands to surface waters via wave action, was found to be a major contributor to poor recreational water quality at the Lake Michigan beaches involved in this study.

Analysis of Variance↗

PubMed2003

Molecular surveillance of Cryptosporidium spp. in raw wastewater in Milwaukee: implications for understanding outbreak occurrence and transmission dynamics.

Six Cryptosporidium spp. were found in 50 of 179 Milwaukee wastewater samples collected weekly over a year. Of the eight subtypes of Cryptosporidium hominis and Cryptosporidium parvum present, allele Ib was found in 14 of 16 samples, and its sequence was identical to that of the subtype in human samples from the 1993 Milwaukee outbreak of cryptosporidiosis.

Animals↗