instruction:
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.
question:
Plasma high-density lipoprotein (HDL) level is inversely correlated with the risk of atherosclerosis. However, the cellular mechanism by which HDL exerts antiatherogenic actions is not well understood. In this study, we focus on the lipid components of HDL as mediators of the lipoprotein-induced antiatherogenic actions.', 'HDL and sphingosine 1-phosphate (S1P) stimulated the migration and survival of human umbilical vein endothelial cells. These responses to HDL and S1P were almost completely inhibited by pertussis toxin and other specific inhibitors for intracellular signaling pathways, although the inhibition profiles of migration and survival were different. The HDL-stimulated migration and survival of the cells were markedly inhibited by antisense oligonucleotides against the S1P receptors EDG-1/S1P1 and EDG-3/S1P3. Cell migration was sensitive to both receptors, but cell survival was exclusively sensitive to S1P1. The S1P-rich fraction and chromatographically purified S1P from HDL stimulated cell migration, but the rest of the fraction did not, as was the case of the cell survival.
answer:
Does high-density lipoprotein stimulate endothelial cell migration and survival through sphingosine 1-phosphate and its receptors?


question:
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.
answer:
Are von Hippel-Lindau disease-associated hemangioblastomas derived from embryologic multipotent cells?


question:
Cam impingement as a known sequelae of slipped capital femoral epiphysis (SCFE) has led to speculation that subclinical SCFEs may be the causative factor in idiopathic cam morphology; alternatively, others have implicated an abnormal extension of the growth plate as a causative factor.', 'To investigate the growth plate tilt angle in 4 patient cohorts: normal patients, patients with idiopathic cam morphology (CamIP), patients with cam morphology secondary to known SCFE (CamSCFE), and patients with incidental findings of an asymptomatic cam (Camasymp).', 'Case-control study; Level of evidence, 3.', 'A database of 192 computed tomography scans of abdomens/pelvises of patients (ages, 5-19 years) with no known orthopaedic issues, reformatted to neutral tilt, inclination, and rotation, were utilized for the normal cohort, the Camasymp cohort, and to create an age- and sex-matched control cohort. In addition, a retrospective review of all patients treated for femoroacetabular impingement (FAI) with preoperative advance imaging was conducted, and patients were separated to CamIP and CamSCFE cohorts. The alpha angle and tilt angle were measured on each hip. Statistical analysis was performed.', 'The mean tilt angle among the normal patients was 12.1°, with 1.9% of the variation in tilt angle being explained by age; each additional year of age decreased the tilt angle by 0.27° (P = .008). The tilt angle for the CamSCFE cohort (mean, 44.5°) was found to be significantly greater than both the CamIP cohort (mean, 5.9°; P < .001) and the control cohort (mean, 12.8°; P < .001). The tilt angle for the CamIP cohort was found to be significantly less than the control cohort (P = .003). The alpha angle and tilt angle were positively correlated in the CamIP cohort, but no correlation was found in the other cohorts. The mean tilt angle of the 18 hips in the Camasymp cohort was 13.9° ± 11.5° (range, -12° to 37°), with 12 hips (67%) in the tilt angle range of CamIP cohort and 6 in the tilt angle range of CamSCFE.
answer:

Is idiopathic Cam Morphology Caused by Subclinical Slipped Capital Femoral Epiphysis : An MRI and CT Study?