Comparison of PNA clamping and direct sequencing for detecting KRAS mutations in matched tumour tissue, cell block, pleural effusion and serum from patients with malignant pleural effusion.

BACKGROUND AND OBJECTIVE: Peptide nucleic acid (PNA)-mediated real-time polymerase chain reaction clamping was recently developed to improve mutation detection sensitivity. Pleural effusion could be a good sample candidate for mutation analysis. To establish if PNA clamping could be used to detect KRAS mutation in particular in pleural effusion, we analysed its diagnostic performance. METHODS: We studied 57 patients with malignant effusion. KRAS mutation was evaluated in samples of matched tumour tissue, cell block, pleural effusion and serum using PNA clamping and direct sequencing. RESULTS: The detection rate of KRAS mutation using pleural effusion was 14% for PNA clamping and 10.5% for direct sequencing. The κ coefficient between the two methods was 0.76 (P value < 0.0001), 1.00 (P value < 0.0001) and 0.87 (P value < 0.0001) in pleural effusion, tissue and cell block, respectively. The diagnostic performance of KRAS mutation detection from pleural effusion compared with the results obtained for all samples combined showed that the sensitivity, specificity, positive predictive value and negative predictive value were as follows: 89, 100, 100 and 98%, respectively for PNA clamping; 67, 100, 100 and 94%, respectively for directing sequencing. CONCLUSIONS: The current study suggests that PNA clamping had a good concordance with direct sequencing for the detection of KRAS mutation in patients with malignant effusion. Furthermore, the good diagnostic performance obtained from pleural effusion samples provides evidence that pleural effusion can be a useful source for detecting KRAS mutation in a clinical setting, in which the collection of tumour tissues is challenging.

Efficacy of team-based financial incentives for smoking cessation in the workplace.

Worksite smoking cessation programs offer accessibility of the target population, availability of occupational health support, and the potential for peer pressure and peer support. The purpose of this study was to identify the efficacy of the financial incentives given to various teams in the workplace. St. Paul's Hospital's employees were enrolled. Each team of employees consisted of smoking participants and non-smoking fellow workers from the same department. The financial incentive of 50000 won (about $45) was rewarded to the team for each successful participant-not to individual members-after the first week and then after one month. If the smokers in the team remained abstinent for a longer time period, the team was given an incentive of 100000 won for each successful participant after 3 and 6 months. A total 28 smoking participants and 6 teams were enrolled. Self-reported abstinence rates validated by urinary cotinine test at 3, 6, and 12 months after the initial cessation were 61%, 54%, and 50%, respectively. Smokers with high nicotine dependence scores or those who began participation 1 month after enrollment initiation had a lower abstinence rate at 3 months, but not at 6 and 12 months. Participants who succeeded at smoking cessation at 12 months were more likely to be older and have a longer smoking duration history. The financial incentives given to teams could be promising and effective to improve long-term rates of smoking cessation. This approach could use peer pressure and peer support in the workplace over a longer period.

Electrochemical detection of 17beta-estradiol using DNA aptamer immobilized gold electrode chip.

An electrochemical detection method for chemical sensing has been developed using a DNA aptamer immobilized gold electrode chip. DNA aptamers specifically binding to 17beta-estradiol were selected by the SELEX (Systematic Evolution of Ligands by EXponential enrichment) process from a random ssDNA library, composed of approximately 7.2 x 10(14) DNA molecules. Gold electrode chips were employed to evaluate the electrochemical signals generated from interactions between the aptamers and the target molecules. The DNA aptamer immobilization on the gold electrode was based on the avidin-biotin interaction. The cyclic voltametry (CV) and square wave voltametry (SWV) values were measured to evaluate the chemical binding to aptamer. When 17beta-estradiol interacted with the DNA aptamer, the current decreased due to the interference of bound 17beta-estradiol with the electron flow produced by a redox reaction between ferrocyanide and ferricyanide. In the negative control experiments, the current decreased only mildly due to the presence of other chemicals.