Evaluation of four DNA extraction methods for the detection of Mycobacterium avium subsp. paratuberculosis by polymerase chain reaction

Polymerase chain reaction (PCR) has been widely used due to its high specificity, sensitivity, and rapid turn-around time. However, inhibitory factors may be co-extracted with the target nucleic acid that will hinder the performance of PCR. In this study, DNA extraction methods for Mycobacterium avium subsp. paratuberculosis were evaluated including rapid lysis, organic extraction, silica-based and magnetic particle-based (MagaZorb) technologies on bacterial cells, and spiked bovine feces. Efficiency of the extraction was determined by PCR end point titration with primers targeting the insertion sequence, IS900. Results of the end point titrations are identical for bacterial cells and spiked feces. Inhibition was observed in PCR with DNA isolated from spiked feces, and a 1/100 dilution was able to alleviate this problem with DNA extracted by MagaZorb. A 1/1000 dilution was required for the other three methods. MagaZorb proved to be more efficient at removing inhibitory factors and required the least labor and completion time. Further evaluation is required for its utilization in other clinical specimens.     

Involvement and detachment in researching sexuality: reflections on the process of semistructured interviewing

In this article, the authors reflect on the utility of the concept of involvement-detachment for researchers involved in a study of the lifeworlds of gay, lesbian, and bisexual young people where one of the researchers was lesbian. They focus in particular on the process of semistructured interviewing in qualitative research and the analysis of material generated by the interviews, noting that complete detachment from the subject of study is neither achievable nor desirable. They discuss the benefit of teamwork in supporting researchers and enhancing the integrity of the research, particularly when the subject is sensitive, the importance of researchers' active management of their own ideological leanings, and the understanding of project management as a conceptual and cognitive process that is fundamental to enhancing research rigor.     

Optimal placement of syringe-exchange programs

Syringe-exchange programs (SEPs) will likely play a major role in slowing the spread of acquired immunodeficiency syndrome (AIDS) among injecting drug users (IDUs), but the success of any single SEP will depend to a large extent on where it is located. We show how the optimal position for a new SEP can be chosen given accurate knowledge of where IDUs live and how far they are willing to travel to an SEP. This information is not normally available, and one of our major points is that SEPs will necessarily be placed in suboptimal locations and will serve fewer ID Us than they otherwise might until it becomes available. Our method for choosing the best SEP placement is illustrated with Manhattan as an idealized example.