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.
--------
Question: Context: Total shoulder arthroplasty (TSA) results in superior clinical outcomes to hemiarthroplasty (HA); however, TSA is a more technical and invasive procedure. This study retrospectively compares perioperative complications after HA and TSA using the National Surgical Quality Improvement Program (NSQIP) database.', 'The NSQIP user file was queried for HA and TSA cases from the years 2005 through 2010. Major complications were defined as life-threatening or debilitating. All complications occurred within 30 days of the initial procedure. We performed multivariate analysis to compare complication rates between the two procedures, controlling for patient comorbidities.', 'The database returned 1,718 patients (HA in 30.4% [n = 523] and TSA in 69.6% [n = 1,195]). The major complication rates in the HA group (5.2%, n = 29) and TSA group (5.1%, n = 61) were similar (P = .706). Rates of blood transfusions for postoperative bleeding in patients undergoing HA (2.3%, n = 12) and TSA (2.9%, n = 35) were indistinguishable (P = .458). Venous thromboembolism was a rare complication, occurring in 0.4% of patients in each group (2 HA patients and 5 TSA patients, P > .999). On multivariate analysis, the operative procedure was not associated with major complications (P = .349); however, emergency case, pulmonary comorbidity, anemia with a hematocrit level lower than 36%, and wound class of III or IV increased the risk of a major complication (P < .05 for all).\Question: Are perioperative complications after hemiarthroplasty and total shoulder arthroplasty equivalent?

Answer: Multivariate analysis of patients undergoing TSA or HA in the NSQIP database suggests that patient factors-not the procedure being performed-are significant predictors of major complications. Controlling for patient comorbidities, we found no increased risk of perioperative major complications in patients undergoing TSA compared with HA.


Question: Context: The cyclooxygenase-2 (cox-2) pathway is now recognized to be important in human cancer development and progression. The gene for cox-2 carries a common single nucleotide polymorphism, T8473C, located within a potential functional region in the 3'-UTR of cox-2 gene was identified. We have investigated the frequencies of cox-2 genotypes in Tunisian population to determine whether that polymorphism was associated with the risk of nasopharyngeal carcinoma (NPC) in Tunisian population.", 'One hundred and eighty-nine NPC patients were compared to 237 healthy controls.', 'The cox-2 T8473C polymorphism was significantly associated with NPC (P=0.031). The CC-genotype and C allele were more frequent in control compared to patients group [CC: OR=0.37; P=0.013; 95% CI: 0.17-0.81; C: OR=0.72; P=0.032; 95% CI: 0.53-0.97]. Multivariate logistic regression analyses revealed that the CC-genotype was associated with a significantly decreased risk of NPC (P=0.013). Tumor sizes, histologic grade, presence of primary lymph node metastases, age or sex were not associated with cox-2 genotypes.\Question: Does the CC-genotype of the cyclooxygenase-2 gene associate with decreased risk of nasopharyngeal carcinoma in a Tunisian population?

Answer: We conclude that the CC-genotype and C allele of cox-2 T8473C gene polymorphism are associated with decreased risk of nasopharyngeal carcinoma in a Tunisian population.


Question: Context: Transient lower esophageal sphincter relaxation is the main mechanism for gastroesophageal reflux. Although there is evidence that transient lower esophageal sphincter relaxations are neurally mediated, another school of thought is that transient lower esophageal sphincter relaxations result from gastric distention, which shortens the sphincter to the point where it opens and the pressure decreases. We assessed the relationship of transient lower esophageal sphincter relaxation to gastroesophageal junction opening in an unsedated human model.', 'Seven healthy volunteers (6 men and 1 woman, aged 18-53 years) were studied while they were sitting. Manometry was performed by using a sleeve catheter passed through 1 nostril. A 5.3-mm endoscope was placed through the other nostril to obtain a retroflexed view of the cardia. The biopsy channel was connected to a barostat to distend the stomach with air at 15 mm Hg for 30 minutes. Manometric and endoscopic video-recording times were synchronized but scored independently.', 'The transient lower esophageal sphincter relaxation onset invariably preceded gastroesophageal junction opening (median, 5.0 seconds; range, 0.5-20.7 seconds; P < .001). The transient lower esophageal sphincter relaxation nadir also typically occurred before gastroesophageal junction opening (median, 2.1 seconds; range, -4.2 to +19.5 seconds; P < .001). Once open, the gastroesophageal junction moved proximally for the duration of the transient lower esophageal sphincter relaxation. Termination of transient lower esophageal sphincter relaxations occurred about the time the time of gastroesophageal junction closure.\Question: Do transient lower esophageal sphincter relaxations result from passive opening of the cardia by gastric distention?

Answer:
These data refute the hypothesis that transient lower esophageal sphincter relaxations result from passive mechanical distraction of the gastroesophageal junction. Rather, transient lower esophageal sphincter relaxations must occur before the gastroesophageal junction can open.