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.

[EX Q]: Context: To investigate a putative increased risk of rectal cancer subsequent to prostatic radiotherapy.', 'In an analysis of the Surveillance, Epidemiology, and End Results registry, we compared men who had radiotherapy for prostatic carcinoma with those treated surgically and those treated with neither modality. Kaplan-Meier analyses for the time to failure from rectal cancer were performed between age-matched subgroups of the three cohorts. Cox proportional hazards analyses were performed to ascertain what influences might affect the incidence of subsequent rectal cancer.', 'In all, 33,831 men were irradiated, 167,607 were treated surgically, and 36,335 received neither modality. Rectal cancers developed in 243 (0.7%) of those irradiated (mean age, 70.7 years), 578 (0.3%) of those treated surgically (68.7 years), and 227 (0.8%) of those treated with neither modality (74.2 years). When age effects and the differences between the surgical and untreated cohorts were controlled for, we were unable to demonstrate any significant increased incidence of rectal cancer in men irradiated for prostatic cancer.
Answer: An increased frequency of rectal cancer after prostatic irradiation, apparent on crude analysis, could be attributed to age confounding and other unmeasured confounders associated with prostate cancer treatment and rectal cancer risk.
[EX A]: Is prostatic irradiation associated with any measurable increase in the risk of subsequent rectal cancer?

[EX Q]: Context: The BXD2 mouse strain spontaneously develops glomerulonephritis and erosive arthritis. The goal of this study was to identify the antigenic target proteins and epitopes and to unravel the mechanisms by which the related conditions arise in BXD2 mice.', 'Individual hybridomas isolated from the spleen of a 10-month-old BXD2 mouse were injected intraperitoneally into nonautoimmune mice for evaluation of pathogenicity of each autoantibody. Autoantigens were immunoprecipitated with the pathogenic autoantibody L3A4. Autoantigens were identified using enzyme-linked immunosorbent assay, Western blotting, 2-dimensional gel electrophoresis, and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MS) and tandem MS. Antigenic epitopes were determined using a high-throughput epitope mapping method.', 'The production of autoantibodies in BXD2 mice occurred in an orderly progression, with peak levels of autoantibodies to nitrotyrosine (NT)-modified enolase, Ro, alpha-actin, and heat-shock proteins (HSPs) preceding peak levels of antihistone, anti-DNA, and rheumatoid factor. Two monoclonal autoantibodies, L3A4 and T56G10, were identified that could induce immune complexes, renal disease, and/or arthritis. Both L3A4 and T56G10 were polyreactive, and each reacted with separate sets of autoantigens. The antigenic targets of L3A4 consisted of NT-modified enolase, ATP5b, alpha-actin, and Hsp70 family proteins including Hspa5 and Hsp74. The antigenic epitopes of NT-modified enolase and Hspa5 exhibited sequence homology and cross-reactivity, suggesting that epitope spreading may occur through a molecular mimicry mechanism.
Answer: The polyreactivity of autoantibodies that target a novel class of autoantigens may enable these autoantibodies to induce erosive arthritis or glomerulonephritis either by direct pathogenic mechanisms or indirectly via Fc or immune complex deposition.
[EX A]: Does production of a novel class of polyreactive pathogenic autoantibodies in BXD2 mice cause glomerulonephritis and arthritis?

[EX Q]: Context: An anti-angiogenic state has been described in patients with preeclampsia, small-for-gestational age (SGA) fetuses and fetal death, and changes in the concentration of circulating angiogenic and anti-angiogenic factors can precede the clinical recognition of preeclampsia and SGA by several weeks. Gene deletion studies demonstrate that a selective group of endothelial growth factors are required for vascular development, including members of the vascular endothelial growth factor (VEGF) family, as well as angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2), both ligands for the tyrosine kinase endothelial cell receptor Tie-2. These angiogenic factors have been proposed to promote angiogenesis in a coordinated and complementary fashion. Soluble Tie-2 (sTie-2) is the soluble form of the Tie-2 receptor, which is detectable in biological fluids. The purpose of this study was to determine whether patients with preeclampsia and mothers who deliver a SGA neonate have changes in the plasma concentrations of sTie-2.', 'This cross-sectional study included patients in the following groups: (1) non-pregnant women (n = 40), (2) women with normal pregnancies (n = 135), (3) patients with preeclampsia (n = 112), and (4) patients who delivered an SGA neonate (n = 53). Maternal plasma concentrations of sTie-2 were measured by a sensitive immunoassay. Non-parametric statistics were used for analysis.', '(1) The median maternal plasma concentration of sTie-2 was lower in normal pregnant women than in non-pregnant women [median 16.0 ng/mL (range 5.0-71.6) vs. median 20.7 ng/mL (range 10.8-52.4), respectively; p = 0.01)). (2) Plasma sTie-2 concentrations in normal pregnancy changed significantly as a function of gestational age. (3) Patients with preeclampsia and those who delivered SGA neonates had a lower median maternal plasma concentration of sTie-2 than those with a normal pregnancy [preeclampsia: median 14.9 ng/mL (range 4.9-67.3); SGA: median 10.9 ng/mL (range 5.1-29.1); normal pregnancy: median 16.0 ng/mL (range 5.0-71.6); p = 0.048 and p < 0.001, respectively]. (4) Patients with SGA neonates had a lower median plasma concentration of sTie-2 than that of those with preeclampsia [median 10.9 ng/mL (range 5.1-29.1) vs. median 14.9 ng/mL (range 4.9-67.3), respectively; p < 0.001]. (5) Patients with early-onset preeclampsia (<or=34 weeks) had lower concentrations of sTie-2 than women with late-onset preeclampsia (>34 weeks) median of delta values: -0.13 ng/mL (range -0.47-0.58) vs. median of delta values: -0.09 ng/mL (range: -0.60-0.58), respectively; p = 0.043]. In contrast, there were no significant differences in the maternal plasma sTie-2 concentration between women with severe and mild preeclampsia (p = 0.6).
Answer: Patients with preeclampsia and those with SGA fetuses have lower median plasma concentrations of soluble Tie-2 than women with normal pregnancies.
[EX A]:
Are preeclampsia and small-for-gestational age associated with decreased concentrations of a factor involved in angiogenesis : soluble Tie-2?