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.

Context: To investigate the incidence of acute kidney injury after cardiac surgery and its association with mortality in a patient population receiving ibuprofen and gentamicin perioperatively.', 'Retrospective study with Cox regression analysis to control for possible preoperative, intraoperative and postoperative confounders.', 'University hospital-based single-center study.', 'All patients who underwent coronary artery bypass grafting valve surgery during 2012.', 'None.', 'Acute surgery within 24 hours of coronary angiography, previous nephrectomy, preoperative sCr >2.26 mg/dL and selective cerebral perfusion during cardiopulmonary bypass were used as exclusion criteria. Acute kidney injury was defined, using the Acute Kidney Injury Network (AKIN) criteria. Six hundred eight patients were included in the study. Mean age was 68.2 9.7 years, and 81% were males. Acute kidney injury was seen in 28.1% of the patients. Overall mortality at one year was 7% and 3% in the no-AKI group. At one year, mortality was 15% in patients with AKIN stage 1 and AKIN stage 2 compared to 70% in AKIN stage 3. A hazard ratio of 2.34 (95% CI: 1.21-4.51, p = 0.011) and 5.62 (95% CI: 2.42-13.06), p<0.0001) were found for AKIN stage 1 and 2/3 combined, respectively.\Question: Is acute kidney injury independently associated with higher mortality after cardiac surgery?
More than 28% of the patients undergoing elective or subacute cardiac surgery developed AKI in this contemporary cohort. Furthermore, acute kidney injury was an independent predictor of increased mortality irrespective of the perioperative risk factors.

Context: The aim of this study was to evaluate the effect of local injection of vasopressin on blood loss and secondary impact on complications during cesarean section in patients with placenta previa.', 'We retrospectively reviewed the medical records of all patients diagnosed with placenta previa admitted to our hospital. Two consecutive periods were compared. During period B, 59 patients underwent the local injection of a vasopressin solution (4 U in 20 mL of saline) into the placental implantation site after placental delivery. During period A, 50 patients underwent cesarean section without vasopressin injection, and were analyzed as a control group. The estimated blood loss was recorded, as were the complications during surgery. In addition, the expression of the vasopressin V1 receptor in uterine smooth muscle was evaluated by immunohistochemistry.', 'The mean estimated blood loss was significantly lower in the vasopressin group than in the control group. There were no statistically significant differences with surgical complications. The vasopressin V1 receptor was highly expressed in smooth muscle cells in the lower segment of the uterine body, whereas the immunoreactivity for the oxytocin receptor was faint in the lower segment.\Question: Does local injection of vasopressin reduce the blood loss during cesarean section in placenta previa?
The local injection of vasopressin into the placental implantation site significantly reduced the blood loss without increasing the morbidity.

Context: Anorectal melanoma (AM) is a rare but highly malignant tumor, displaying histologic and immunohistochemical features very similar to cutaneous melanoma (CM). Because BRAF mutations were recently identified in the majority of CM and nevi, we investigated AM for BRAF mutations and mutations of NRAS , an additional component of the MAPK-signalling pathway.', 'DNA from formalin-fixed and paraffin-embedded AM was PCR amplified and sequenced.', "We detected BRAF mutations in 2 of 19 cases and NRAS mutations in none of the cases. Mutations in exon 15 of BRAF were present in only 1 tumor (1 of 19 cases). The A1800T base exchange represented a novel mutation and resulted in a K600N transition in an AM from a 96-year-old white man who presented with rectal bleeding and painful sitting of a few weeks' duration. The second positive AM case, a 69-year-old white man who presented with painless rectal bleeding and clinical symptoms of an intestinal constipation showed a novel missense mutation (C1327T leading to R443W conversion) in BRAF exon 11. None of the AM cases displayed the oncogenic V599E mutation preponderating in CM.\Question: Do bRAF mutations distinguish anorectal from cutaneous melanoma at the molecular level?
With regard to the frequency of V599E BRAF mutations, AM significantly differs from CM (P < or = .0001), which suggests that BRAF mutations distinguish anorectal from cutaneous melanoma at the molecular level.