instruction:
Given a passage with a context and an answer, 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.
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Context: The failure of in utero transplantation in immune-competent recipients suggests the existence of a fetal immune barrier. The importance of donor major histocompatibility complex (MHC) class I expression in the induction of prenatal tolerance remains undefined. We hypothesized that donor cell MHC class I expression facilitates engraftment in prenatal allogeneic recipients rather than promoting immune rejection.', 'B6.Ly5.2 (class I(+)) or B6.TAP(-/-) (class I(-)) murine fetal liver cells were transplanted into age-matched allogeneic fetal recipients. Survival to weaning and subsequent growth was assessed. Engraftment rates and peripheral blood chimerism levels were measured serially.', 'The presence or absence of class I expression did not affect survival or growth of recipients and no graft-vs-host disease developed. Allogeneic recipients of B6.Ly5.2 cells exhibited significantly higher levels of donor hematopoietic chimerism when compared to recipients of B6.TAP(-/-) cells (27% + 10% vs 11% + 8%; P = .004) that deteriorated further over time.
Answer: Donor class I MHC antigen expression is essential for stable long-term engraftment and maintenance of donor-specific tolerance. Further studies are needed to better characterize the role of the fetal innate immune system in prenatal allotransplantation.
answer:
Does donor major histocompatibility complex class I expression determine the outcome of prenatal transplantation?

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Context: The epigenetic mechanism of tumorigenesis in pancreatic intraductal papillary mucinous neoplasm (IPMN) remains largely unknown. The aim of this study is to examine the role of enhancer of zeste homologue 2 (EZH2) alteration in pancreatic IPMN progression.', 'Fifty-four surgically resected pancreatic IPMN specimens, including a total of 181 lesions (normal duct in 48, adenoma in 50, borderline atypia in 53, carcinoma in situ (CIS) in 19, and invasive carcinoma in 11) were analyzed by immunohistochemical staining (EZH2, Ki-67, p27Kip1). Using paraffin embedded sections, total RNA was successfully extracted from 20 IPMN lesions (borderline IPMN in 9, CIS in 6, invasive carcinoma in 5) and 7 pancreatic normal ducts, and then levels of EZH2 and p27Kip1 mRNA were analyzed by real time PCR.', 'In immunohistochemical analysis, cell proliferative activity revealed by Ki-67 positive nuclei was increased during IPMN progression (normal duct<adenoma<borderline atypia<CIS invasive carcinoma). EZH2 expression displayed a similar pattern (normal duct<adenoma<borderline atypia<CIS invasive carcinoma) with cell proliferative activity. EZH2 expression in malignant (CIS and invasive carcinoma) IPMNs was significantly higher than that in adenoma and borderline-atypia IPMNs. EZH2 expression level in IPMN lesions was positively correlated with the Ki-67 positive nuclear ratio (p<0.0001). EZH2-positive cells in malignant IPMN did not express p27Kip1. EZH2 mRNA expressions in malignant lesions were significantly higher than those in benign lesions (p<0.0001). In contrast, p27Kip1 mRNA in malignant lesions was significantly decreased compared to those in benign lesion (p<0.05), and there was an inverse correlation between EZH2 and p27Kip1 mRNA levels (p = 0.0109).
Answer: EZH2 is associated with the accelerated cell proliferation and malignant step in pancreatic IPMN via the downregulation of p27Kip1.
answer:
Is eZH2 associated with malignant behavior in pancreatic IPMN via p27Kip1 downregulation?

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Context: Our purpose was to study the incidence and location of histologic evidence of intrauterine bleeding in preterm and term placentas.', "A total of 462 consecutive placentas delivered at < 32 weeks' gestation, from which cases of placenta previa, stillbirth, and multiple gestation were excluded, were compared with 108 consecutive term placentas (with similar exclusion criteria) in regard to the presence of hemosiderin in decidua of basal plate or placental membranes. Of the 462 preterm cases, 448 charts made specific reference to the presence or absence of vaginal bleeding. Bloody show alone was not considered bleeding. The blinded scoring of lesions (including acute ascending infection, uteroplacental vascular pathologic processes and related ischemic damage, chronic inflammation, and coagulation related lesions) was analyzed by contingency tables (p < 0.05 significant).", 'A total of 196 of 462 (43%) preterm placentas had any decidual hemosiderin compared with one of 108 (0.8%) at term (p < 0.00001). Among the preterm cases, hemosiderin was significantly more common in preeclampsia (45/76, 60%) and in cases clinically diagnosed as nonhypertensive abruptio placentae (21/33, 64%) than in premature membrane rupture (72/192, 37.5%) and preterm labor (58/161, 36%, p < 0.003). The incidence of placental lesions in preterm cases with extraplacental membrane hemosiderin was not different than it was in cases without hemosiderin. Placental lesions related to basal-plate decidual hemosiderin in the preterm cases were villous infarct (p < 0.0001), uteroplacental vessels with absence of physiologic change (p < 0.003) and increased numbers of circulating nucleated erythrocytes (p < 0.0007), uteroplacental thrombosis (p < 0.0001), and villous fibrosis (p < 0.0001) and hypovascularity (p < 0.0001). Among the preterm cases, 23 of 48 (48%) with first-trimester bleeding, 33 of 66 (50%) with second-trimester bleeding, and 31 of 64 (48%) with multiple episodes of bleeding had decidual hemosiderin (p < 0.0001). A clinical history of gestational bleeding was significantly less common in cases of preterm preeclampsia with histologic evidence of bleeding (four of 73, 5.5%) than in nonhypertensive abruptio placentae (18/31, 58%), premature rupture of membranes (52/183, 28%), or preterm labor (31/161, 19%, p < 0.0001). Hemosiderin was not related to clinical bleeding < 72 hours of delivery (p > 0.20).
Answer: Decidual bleeding is common in all clinical types of preterm birth and is most common in preterm preeclampsia and nonhypertensive abruption placentae. A clinical history of bleeding is not correlated with the presence of decidual hemosiderin. Bleeding in the basal plate is related to histologic evidence of chronic uteroplacental vascular pathologic processes, which in cases of spontaneous prematurity (premature rupture of membranes, preterm labor, nonhypertensive abruptio placentae) may be associated with decidual bleeding which occasionally may be clinically manifested as gestational bleeding.
answer:
Is histologic evidence of old intrauterine bleeding more frequent in prematurity?