A Genetic Screen Using the PiggyBac Transposon in Haploid Cells Identifies Parp1 as a Mediator of Olaparib Toxicity.

A Genetic Screen Using the PiggyBac Transposon in Haploid Cells Identifies Parp1 as a Mediator of Olaparib Toxicity.

PLoS One. 2013; 8(4): e61520
Pettitt SJ, Rehman FL, Bajrami I, Brough R, Wallberg F, Kozarewa I, Fenwick K, Assiotis I, Chen L, Campbell J, Lord CJ, Ashworth A

Genetic perturbation screens have the potential to dissect a wide range of cellular phenotypes. Such screens have historically been difficult in diploid mammalian cells. The recent derivation of haploid embryonic stem cells provides an opportunity to cause loss of function mutants with a random mutagen in a mammalian cell with a normal genetic background. We describe an approach to genetic screens that exploits the highly active piggyBac transposon in haploid mammalian cells. As an example of haploid transposon (HTP) screening, we apply this approach to identifying determinants of cancer drug toxicity and resistance. In a screen for 6-thioguanine resistance we recovered components of the DNA mismatch repair pathway, a known requirement for toxicity. In a further screen for resistance to the clinical poly(ADP-ribose) polymerase (PARP) inhibitor olaparib we recovered multiple Parp1 mutants. Our results show that olaparib toxicity to normal cells is mediated predominantly via Parp1, and suggest that the clinical side effects of olaparib may be on target. The transposon mutant libraries are stable and can be readily reused to screen other drugs. The screening protocol described has several advantages over other methods such as RNA interference: it is rapid and low cost, and mutations can be easily reverted to establish causality. HubMed – drug


Linkage of Presumptive Multidrug Resistant Tuberculosis (MDR-TB) Patients to Diagnostic and Treatment Services in Cambodia.

PLoS One. 2013; 8(4): e59903
Khann S, Mao ET, Rajendra YP, Satyanarayana S, Nagaraja SB, Kumar AM

National Tuberculosis Programme, Cambodia.In a cohort of TB patients, to ascertain the proportion of patients who fulfil the criteria for presumptive MDR-TB, assess whether they underwent investigation for MDR-TB, and the results of the culture and drug susceptibility testing (DST).A cross sectional record review of TB patients registered for treatment between July-December 2011.Of 19,236 TB patients registered, 409 (2%) fulfilled the criteria of presumptive MDR-TB; of these, 187 (46%) were examined for culture. This proportion was higher among relapse, failure, return after default (RAD) and non-converters at 3 months of new smear positive TB patients (>60%) as compared to non-converters at 2 months of new TB cases (<20%). Nearly two thirds (n?=?113) of the samples were culture positive; of these, three-fourth (n?=?85) grew Mycobacterium tuberculosis complex (MTBc) and one-fourth (n?=?28) grew non-tuberculous Mycobacteria. DST results were available for 96% of the MTBc isolates. Overall, 21 patients were diagnosed as MDR-TB (all diagnosed among retreatment TB cases and none from non-converters) and all of them were initiated on MDR-TB treatment.There is a need to strengthen mechanisms for linking patients with presumptive MDR-TB to culture centers. The policy of testing non-converters for culture and DST needs to be reviewed. HubMed – drug


Prevalence of HIV, STIs, and Risk Behaviors in a Cross-Sectional Community- and Clinic-Based Sample of Men Who Have Sex with Men (MSM) in Lima, Peru.

PLoS One. 2013; 8(4): e59072
Perez-Brumer AG, Konda KA, Salvatierra HJ, Segura ER, Hall ER, Montano SM, Coates TJ, Klausner JD, Caceres CF, Clark JL

Further research is necessary to understand the factors contributing to the high prevalence of HIV/STIs among men who have sex with men (MSM) in Peru. We compared HIV/STI prevalence and risk factors between two non-probability samples of MSM, one passively enrolled from an STI clinic and the other actively enrolled from community venues surrounding the clinic in Lima, Peru.A total of 560 self-identified MSM were enrolled between May-December, 2007. 438 subjects enrolled from a municipal STI clinic and 122 subjects enrolled during community outreach visits. All participants underwent screening for HIV, syphilis, HSV-2, gonorrhoea, and chlamydia and completed a survey assessing their history of HIV/STIs, prior HIV testing, and sexual behavior.HIV prevalence was significantly higher among MSM enrolled from the clinic, with previously undiagnosed HIV identified in 9.1% compared with 2.6% of community participants. 15.4 % of all MSM screened were infected with ?1 curable STI, 7.4% with early syphilis (RPR?1?16) and 5.5% with urethral gonorrhoea and/or chlamydia. No significant differences between populations were reported in prevalence of STIs, number of male sex partners, history of unprotected anal intercourse, or alcohol and/or drug use prior to sex. Exchange of sex for money or goods was reported by 33.5% of MSM enrolled from the clinic and 21.2% of MSM from the community (p?=?0.01).Our data demonstrate that the prevalence of HIV and STIs, including syphilis, gonorrhoea, and chlamydia are extremely high among MSM enrolled from both clinic and community venues in urban Peru. New strategies are needed to address differences in HIV/STI epidemiology between clinic- and community-enrolled samples of MSM. HubMed – drug