In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

[EX Q]: Context: The blasticidin S resistance gene (bsr) is a selectable marker used for gene transfer experiments. The bsr gene encodes for blasticidin S (BS) deaminase, which has a specific activity upon BS. Therefore, its expression is supposed to be harmless in cells. The work reported on herein consisted of experiments to verify a possible toxicity of bsr on mammalian cells, which include several cell lines and primary cultures.', 'Murine keratinocyte BALB/MK and human primary keratinocyte cells transduced with the retroviral vector LBmSN, which has an improved expression system of bsr, namely bsrm, died in five days after the transduction. Meanwhile the control vector LBSN, which expresses bsr, did not provoke cell death. The lethal activity of bsrm was observed only in human keratinocytes and BALB/MK cells among the cell types tested here. Death appears to be mediated by a factor, which is secreted by the BALB/MK transduced cells.\Question: Is over expression of the selectable marker blasticidin S deaminase gene toxic to human keratinocytes and murine BALB/MK cells?
[EX A]: By our study we demonstrated that the expression of bsrm gene is toxic to human keratinocytes and BALB/MK cells. It is likely over expression of BS deaminase gene is responsible for the death.

[EX Q]: Context: Non-viral gene transfer efficiency is low as compared to viral vector systems. Here we describe the discovery of new drugs that are capable of enhancing non-viral gene transfer into mammalian cells using a novel two-stage screening procedure.', 'First, potential candidates are preselected from a molecular library at various concentrations by a semi-automated yeast transfection screen (YTS). The maximal transfection efficiency of every positive drug is subsequently determined in independent experiments at the optimal concentration and compared to the inhibitory effect of the drug on cell growth (IC50). In a subsequent mammalian cell transfection screen (MTS), the maximal transfection efficiency and the IC50 are determined for all preselected drugs using a human cell line and a luciferase reporter gene construct.', 'Employing our novel system we have been able to identify a new class of transfection enhancers, the tricyclic antidepressants (i.e. doxepin, maprotiline, desipramine and amoxapine). All positive drugs enhanced gene transfer in both yeast and human cell lines, but lower concentrations were sufficient for mammalian cells. With a triple combination of doxepin, amoxapine and chloroquine we obtained a transfection efficiency that exceeded that of chloroquine, one of the best-known transfection enhancers of mammalian cells, by nearly one order of magnitude.\Question: Does novel two-stage screening procedure lead to the identification of a new class of transfection enhancers?
[EX A]: Non-viral gene transfer efficiency can be increased significantly using new transfection enhancers that are identified by a novel, semi-automated two-stage screening system employing yeast cells in the first and specific human target cells in the second round.

[EX Q]: Context: The use of a system for continuous control of endotracheal tube cuff pressure reduced the incidence of ventilator-associated pneumonia (VAP) in one randomized controlled trial (RCT) with 112 patients but not in another RCT with 142 patients. In several guidelines on the prevention of VAP, the use of a system for continuous or intermittent control of endotracheal cuff pressure is not reviewed. The objective of this study was to compare the incidence of VAP in a large sample of patients (n=284) treated with either continuous or intermittent control of endotracheal tube cuff pressure.', 'We performed a prospective observational study of patients undergoing mechanical ventilation during more than 48 hours in an intensive care unit (ICU) using either continuous or intermittent endotracheal tube cuff pressure control. Multivariate logistic regression analysis (MLRA) and Cox proportional hazard regression analysis were used to predict VAP. The magnitude of the effect was expressed as odds ratio (OR) or hazard ratio (HR), respectively, and 95% confidence interval (CI).', 'We found a lower incidence of VAP with the continuous (n=150) than with the intermittent (n=134) pressure control system (22.0% versus 11.2%; p=0.02). MLRA showed that the continuous pressure control system (OR=0.45; 95% CI=0.22-0.89; p=0.02) and the use of an endotracheal tube incorporating a lumen for subglottic secretion drainage (SSD) (OR=0.39; 95% CI=0.19-0.84; p=0.02) were protective factors against VAP. Cox regression analysis showed that the continuous pressure control system (HR=0.45; 95% CI=0.24-0.84; p=0.01) and the use of an endotracheal tube incorporating a lumen for SSD (HR=0.29; 95% CI=0.15-0.56; p<0.001) were protective factors against VAP. However, the interaction between type of endotracheal cuff pressure control system (continuous or intermittent) and endotracheal tube (with or without SSD) was not statistically significant in MLRA (OR=0.41; 95% CI=0.07-2.37; p=0.32) or in Cox analysis (HR=0.35; 95% CI=0.06-1.84; p=0.21).\Question: Does continuous endotracheal tube cuff pressure control system protect against ventilator-associated pneumonia?
[EX A]:
The use of a continuous endotracheal cuff pressure control system and/or an endotracheal tube with a lumen for SSD could help to prevent VAP in patients requiring more than 48 hours of mechanical ventilation.