Knock-down resistance due to a point mutation in the voltage gated sodium channel at L1014 residue (kdr) is a common mechanism of resistance to DDT and pyrethroids.
The selection of this resistance may pose a serious threat to the success of the pyrethroid-impregnated bed net programme. This study reports the presence of kdr mutation (L1014F) in a field population of An. culicifacies s.l. and three new PCR-based methods for kdr genotyping.
Methods: The IIS4-IIS5 linker to IIS6 segments of the para type voltage gated sodium channel gene of DDT and pyrethroid resistant An. culicifacies s.l. population BMS202 clinical trial from the Surat district of India was sequenced. This revealed the presence of an A-to-T substitution at position 1014 leading to a leucine-phenylalanine mutation (L1014F) in a few individuals. Three molecular methods viz. Allele Specific PCR (AS-PCR), an Amplification Refractory Mutation System NVP-HSP990 chemical structure (ARMS) and Primer Introduced Restriction Analysis-PCR (PIRA-PCR) were developed and tested for kdr genotyping. The specificity of the three assays was validated following DNA sequencing of the samples genotyped.
Results: The genotyping of this An. culicifacies s.l. population by the three PCR based assays provided consistent result and were in agreement with DNA sequencing
result. A low frequency of the kdr allele mostly in heterozygous condition was observed in the resistant population. Frequencies of the different genotypes were in Hardy-Weinberg equilibrium.
Conclusion: The Leu-Phe mutation, which generates MDV3100 the kdr phenotype in many insects, was detected in a pyrethroid and DDT resistant An. culicifacies s.l. population. Three PCR-based methods were developed for kdr genotyping. All the three assays were specific. The ARMS method
was refractory to non-specific amplification in non-stringent amplification conditions. The PIRA-PCR assay is able to detect both the codons for the phenylalanine mutation at kdr locus, i.e., TTT and TTC, in a single assay, although the latter codon was not found in the population genotyped.”
“Improvements in overactive bladder (OAB) symptoms and health-related quality of life (HRQL) were assessed during a 24-week study of tolterodine extended release (TOL ER) in sexually active women with OAB and urgency urinary incontinence (UUI). A 12-week, double-blind, randomized, placebo-controlled trial was followed by a 12-week open-label phase. Sexually active women reported symptoms for a parts per thousand yen3 months. Subjects completed bladder diaries and HRQL measures at baseline and weeks 12 and 24. One hundred sixty-one women received TOL ER for 24 weeks. Women reported significant improvements in all end points at week 12 that were maintained or improved at 24 weeks. At week 24, 70% of subjects reported no UUI episodes. TOL ER resulted in improvements in OAB symptoms and HRQL that were maintained or greater with 6 months of use.