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.

[Q]: Context: Some subjects with suspected asthma and a negative exercise challenge test (ECT) demonstrate improved expiratory flow rates after administration of bronchodilators (BD) at the end of the ECT (unpublished observation). This study investigated whether this response predicts the presence of bronchial hyperreactivity (BHR).', 'The study population included 133 young adults (29.4% women) 21.1 +/- 4.2 years of age who underwent ECT and a methacholine challenge test (MCT). A receiver-operator-characteristic curve was used to calculate the optimal cutoff level of the response to BD as a predictor of BHR according to MCT.', 'Using a MCT cutoff level of PC(20) </= 4 mg/mL showed BHR in 12.8% of subjects. Failure to improve FEV(1) by 8% after BD administration predicted the absence of BHR with sensitivity, specificity, and positive and negative predictive values of 76.5%, 68.4%, 25.3%, and 95.5%, respectively. Avoiding MCT in subjects with less than 8% response to BD would have saved 62.5% of the MCTs and would have missed only four (3%) patients with BHR.\Question: Does response to bronchodilators after exercise challenge predict bronchial hyperreactivity?
[A]: BD should be administered routinely after ECT, as the response may be used as a simple, inexpensive tool to predict BHR in young patients and may substantially reduce the number of unnecessary MCTs.


[Q]: Context: Intrathecal magnesium sulfate coinfusion with morphine increases antinociception in normal rats; however, because magnesium also delays the onset of tolerance, it is not clear whether this additional antinociception is a result of potentiated analgesia or tolerance abatement. We examined the antinociceptive interaction of intrathecal (IT) bolus magnesium sulfate and morphine in morphine naive rats and those with mechanical allodynia after a surgical incision. After intrathecal catheter implantation, rats were given preinjections of magnesium or saline, followed by injections of morphine or saline. In morphine naïve rats, IT bolus magnesium sulfate 281 and 375 microg followed by IT morphine 0.25 or 0.5 nmol enhanced peak antinociception and area under the response versus time curve two-to-three-fold in the tail-flick test as compared with morphine alone. Likewise, in rats with incisional pain, IT bolus magnesium sulfate 188 and 375 microg followed by morphine 0.5 nmol reduced mechanical allodynia, whereas morphine 0.5 nmol alone did not. This study suggests that IT magnesium sulfate potentiates morphine at a spinal site of action.\Question: Does magnesium sulfate potentiate morphine antinociception at the spinal level?
[A]: Magnesium sulfate potentiates morphine analgesia when coadministered intrathecally in normal rats, and in an animal model of mechanical allodynia after a surgical incision. These results suggest that intrathecal administration of magnesium sulfate may be a useful adjunct to spinal morphine analgesia.


[Q]: Context: To assess whether intratumoral heterogeneity measured by (18)F-FDG PET texture analysis has potential as a prognostic imaging biomarker in patients with pancreatic ductal adenocarcinoma (PDAC).', 'We evaluated a cohort of 137 patients with newly diagnosed PDAC who underwent pretreatment (18)F-FDG PET/CT from January 2008 to December 2010. First-order (histogram indices) and higher-order (grey-level run length, difference, size zone matrices) textural features of primary tumours were extracted by PET texture analysis. Conventional PET parameters including metabolic tumour volume (MTV), total lesion glycolysis (TLG), and standardized uptake value (SUV) were also measured. To assess and compare the predictive performance of imaging biomarkers, time-dependent receiver operating characteristic (ROC) curves for censored survival data and areas under the ROC curve (AUC) at 2\xa0years after diagnosis were used. Associations between imaging biomarkers and overall survival were assessed using Cox proportional hazards regression models.', 'The best imaging biomarker for overall survival prediction was first-order entropy (AUC\u2009=\u20090.720), followed by TLG (AUC\u2009=\u20090.697), MTV (AUC\u2009=\u20090.692), and maximum SUV (AUC\u2009=\u20090.625). After adjusting for age, sex, clinical stage, tumour size and serum CA19-9 level, multivariable Cox analysis demonstrated that higher entropy (hazard ratio, HR, 5.59; P\u2009=\u20090.028) was independently associated with worse survival, whereas TLG (HR 0.98; P\u2009=\u20090.875) was not an independent prognostic factor.\Question: Does intratumoral heterogeneity of ( 18 ) F-FDG uptake predict survival in patients with pancreatic ductal adenocarcinoma?
[A]:
Intratumoral heterogeneity of (18)F-FDG uptake measured by PET texture analysis is an independent predictor of survival along with tumour stage and serum CA19-9 level in patients with PDAC. In addition, first-order entropy as a measure of intratumoral metabolic heterogeneity is a better quantitative imaging biomarker of prognosis than conventional PET parameters.