TASK DEFINITION: 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.
PROBLEM: Context: Hypercontracture is an important mechanism of myocyte death during reperfusion. cGMP modulates the sensitivity of contractile myofilaments to Ca2+, and increasing cGMP concentration during the last minutes of anoxia prevents reoxygenation-induced hypercontracture in isolated cardiomyocytes. The purpose of this study was to determine whether stimulation of particulate guanylyl cyclase with the natriuretic peptide urodilatin, given at the time of reperfusion, reduces myocardial necrosis in the rat heart submitted to transient ischemia.', 'Isolated rat hearts (n = 38) were submitted to either 40 or 60 min of no-flow ischemia and 2 h of reperfusion, and were allocated to receive or not receive 0.05 microM urodilatin during the first 15 min of reperfusion or non-reperfusion treatment.', 'A marked reduction in myocardial cGMP concentration was observed in control hearts during reperfusion after 40 or 60 min of ischemia. Urodilatin significantly attenuated cGMP depletion during initial reperfusion, markedly improved contractile recovery after 40 min of ischemia (P < 0.0309), and reduced reperfusion-induced increase in left ventricular end-diastolic pressure (P = 0.0139), LDH release (P = 0.0263), and contraction band necrosis (P = 0.0179) after 60 min of ischemia. The beneficial effect of urodilatin was reproduced by the membrane permeable cGMP analog 8-Bromo-cGMP.\Question: Does urodilatin limit acute reperfusion injury in the isolated rat heart?

SOLUTION: These results indicate that reduced cGMP concentration may impair myocyte survival during reperfusion. Stimulation of particulate guanylyl cyclase may appear as a new strategy to prevent immediate lethal reperfusion injury.

PROBLEM: 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?

SOLUTION: 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.

PROBLEM: Context: Patients suffering traumatic brain and chest wall injuries are often difficult to liberate from the ventilator yet best timing of tracheostomy remains ill-defined. While prior studies have addressed early versus late tracheostomy, they generally suffer from the use of historical controls, which cannot account for variations in management over time. Propensity scoring can be utilized to identify controls from the same patient population, minimizing impact of confounding variables. The purpose of this study was to determine outcomes associated with early versus late tracheostomy by application of propensity scoring.', 'Patients requiring intubation within 48h and receiving tracheostomy from January 2010 to June 2012 were identified. Early tracheostomy (ET) was a tracheostomy performed by the fifth hospital day. ET patients were matched to late tracheostomy patients (LT, tracheostomy after day 5) using propensity scoring and compared for multiple outcomes. Cost for services was calculated using average daily billing rates at our institution.', 'One hundred and six patients were included, 53 each in the ET (mean day tracheostomy=4) and the LT (mean day tracheostomy=10) cohorts. The average age was 47 years and 94% suffered blunt injury, with an average NISS of 23.7. Patients in the ET group had significantly shorter TICU LOS (21.4 days vs. 28.6 days, p<0.0001) and significantly fewer ventilator days (16.7 days vs. 21.9, p<0.0001) compared to the LT group. ET patients also had significantly less VAP (34% vs. 64.2%, p=0.0019).\Question: Does early tracheostomy in trauma patients save time and money?

SOLUTION:
In the current era of increased health-care costs, early tracheostomy significantly decreased both pulmonary morbidity and critical care resource utilization. This translates to an appreciable cost savings, at minimum $52,173 per patient and a potential total savings of $2.8million/year for the entire LT cohort. For trauma patients requiring prolonged ventilator support, early tracheostomy should be performed.