Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Input: Consider Input: To determine the origin of the neoplastic cell in central nervous system (CNS) hemangioblastomas in von Hippel-Lindau disease (VHL) and its role in tumor formation and distribution, we characterized and differentiated neoplastic cells from hemangioblastomas removed from VHL patients.', 'A total of 31 CNS hemangioblastomas from 25 VHL patients were resected and analyzed. Tumor cells from the hemangioblastomas were characterized, grown, and differentiated into multiple lineages. Resected hemangioblastomas were located in the cerebellum (11 tumors), brainstem (five tumors), and spinal cord (15 tumors). Consistent with an embryologically derived hemangioblast, the neoplastic cells demonstrated coexpression of the mesodermal markers brachyury, Flk-1 (vascular endothelial growth factor-2), and stem cell leukemia (Scl). The neoplastic cells also expressed hematopoietic stem cell antigens and receptors including CD133, CD34, c-kit, Scl, erythropoietin, and erythropoietin receptor. Under specific microenvironments, neoplastic cells (hemangioblasts) were expanded and differentiated into erythrocytic, granulocytic, and endothelial progenitors. Deletion of the wild-type VHL allele in the hematopoietic and endothelial progeny confirmed their neoplastic origin.

Output: Are von Hippel-Lindau disease-associated hemangioblastomas derived from embryologic multipotent cells?


Input: Consider Input: The objective in lung transplantation is to prolong life, but the survival effect in patients with chronic obstructive pulmonary disease (COPD) or alpha1-anti-trypsin deficiency emphysema is still unresolved. This study assesses the impact of diagnosis, single-lung transplantation (SLT) vs bilateral lung transplantation (BLT) and timing of transplantation on survival in a national cohort.', 'In 219 consecutive patients accepted onto the lung transplantation waiting list in Norway, 1990 to 2003, we assessed predictors of death: (1) on the waiting list; (2) <or=90 days after transplantation; and (3) >90 days after transplantation. For each period we used Cox regression, including age, gender, diagnosis, baseline pulmonary function tests, cardiac catheterization data, exercise capacity and transplant type, as potential predictors. Survival benefit was assessed graphically by combining adjusted survival curves after transplantation with the curve for those waiting, modeling transplantation after 6, 12 or 24 months.', 'Mean patient age was 49 years (SD 10), with 55% women. High forced expiratory volume in 1 second (FEV(1)) percentage predicted death on the waiting list. Diagnoses other than COPD/emphysema and receiving SLT were associated with death <or=90 days after transplantation. Only low forced vital capacity (FVC) percentage predicted death >90 days after transplantation. In COPD/emphysema, there was no clear survival benefit from BLT or SLT. For patients in the "Other" group, the data suggest a survival benefit from BLT.

Output: Is lung transplantation in patients with chronic obstructive pulmonary disease in a national cohort without obvious survival benefit?


Input: Consider Input: Despite recent advances in preoperative diagnostic imaging and operative techniques, biliary variation of the donor still remains a challenge in the procurement of graft. The supraportal right bile duct (BD) variant including presentation as trifurcation is a potential trap for injuring the remnant bile duct of donor.', 'Before living/related-donor liver transplantation (LRLT), cholangiogram with magnetic resonance images of each donor was performed as a routine. After exploration of the donor before hilar dissection, intraoperative chloangiography (IOC) was routinely performed. Among the supraportal right bile duct variants, if the preoperative cholangiography showed a suspected trifurcation of the bile duct, we then performed 3 sessions of IOC during liver graft procurement, including prior to hilar dissection, before the division of bile ducts and after the division. We reviewed the cholangiogram and the postoperative laboratory data of a consecutive series of 25 donors of LRLT.', 'There was no division injury of the remnant bile duct of all of the donors.


Output: Is repeated introperative cholangiography helpful for donor safety in the procurement of right liver graft with supraportal right bile duct variants in living-donor liver transplantation?