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.

Example Input: To date, cardiac catheterization and endomyocardial biopsy have been considered the "gold standard" for rejection surveillance after heart transplantation. Factors such as patient size (i.e., infant transplantation), loss of vascular access after repeated catheterizations, and anesthesia requirements all present unique problems and risks related to pediatric rejection surveillance. Therefore, additional methods to monitor for rejection in a non-invasive, reliable and frequent manner have been sought. We studied the utility of echocardiographic measurement of the left ventricular myocardial performance index (LVMPI), a reproducible measure of combined systolic and diastolic performance, in pediatric heart transplant recipients as a method of identifying acute rejection.', 'Two-dimensional/Doppler echocardiographic studies (n = 36) were performed on 21 cardiac transplant patients (ages 6.2 to 21.9 years) at the time of endomyocardial biopsy. The LVMPI, the sum of the isovolumic contraction time and isovolumic relaxation time divided by aortic ejection time, was determined at each study, as well as other echocardiographic measures of systolic and diastolic function. Patients were grouped by concurrent histologic rejection grade and the results compared between groups.', 'Significant differences in LVMPI (p < 0.001) were noted between patients with no rejection (Grade 0; n = 23) and those with moderate to severe rejection (Grade 3; n = 5), as well as between those with no rejection and those with focal moderate (Grade 2; n = 8) rejection (p < 0.05). The LVMPI was 0.42 +/- 0.03 (mean +/- SEM) for the group without rejection, 0.57 +/- 0.06 for those with Grade 2 rejection and 0.73 +/- 0.05 for those with Grade 3 rejection. Although 9 of the 23 studies in the non-rejection group had LVMPI values exceeding 0.44 (upper threshold value), 12 of 13 patients in the rejection groups exceeded this threshold. LVMPI >or= 0.64 was associated with significant rejection in all cases in this study (n = 7). No significant differences were noted between groups for left ventricular ejection fraction or shortening fraction, percent septal or posterior wall thickening, left ventricular mass index or mitral valve deceleration time. In addition, for those individual patients with multiple studies, the LVMPI consistently increased with higher rejection grades and decreased after therapy.
Example Output: Does increased myocardial performance index correlate with biopsy-proven rejection in pediatric heart transplant recipients?

Example Input: To investigate B7-H4 expression and its correlation with the number of infiltrating T lymphocytes and cytokine production by those lymphocytes in human cervical cancer and to determine the effect of recombinant B7-H4 on the active peripheral blood T cells of the patients in vitro.', 'B7-H4 expression was detected in 67 cases of cervical cancer using immunohistochemical staining. Tumor-infiltrating CD8(+)T, CD4(+)T, and FOXP3(+) (Forkhead Box P3) T lymphocytes and their levels of IFN- and TGF- production were determined by immunofluorescent double-staining. After the peripheral blood T lymphocytes of patients were co-cultured with B7-H4, proliferation, apoptosis, and cell subtypes were analyzed using flow cytometry. Cytokines in the supernatant were detected by ELISA.', "B7-H4 was expressed in 46% (31/67) of the cases of cervical cancer. The number of infiltrating CD8(+)T lymphocytes and their IFN- production in positive B7-H4 expression cervical cancers was significantly lower than in negative B7-H4 cases (P<0.01, P<0.05), but there was no significant difference between cases positive and negative for B7-H4 with respect to infiltrating FOXP3(+)T and CD4(+)T cells or TGF-1 production. After co-culture with B7-H4 for 48 h, the patients' activated T lymphocytes were arrested at G1/G2 phase. The Ki67 positive rates of CD4(+)T and CD8(+)T cells were 2.13 0.13% and 1.03 1.33%, and they were lower than in the blank group. The proportion of CD4(+)T and CD8(+)T cells decreased, but CD4(+)T/CD8(+)T and the proportion of CD4(+)CD25(+)Foxp3(+)T cells increased. In addition, concentrations of IL-10 and TGF-1 in the supernatant of co-cultured T cells increased significantly (P<0.05, P<0.05), but that of IFN- decreased. B7-H4 had no significant effect on apoptosis of the T cells.
Example Output: Does b7-H4 overexpression impair the immune response of T cells in human cervical carcinomas?

Example Input: To determine if the presence of perineural invasion (PNI) predicts biochemical recurrence in patients who underwent low-dose-rate brachytherapy for the treatment of localized prostate cancer.', 'A retrospective case control matching study was performed. The records of 651 patients treated with brachytherapy between 1996 and 2003 were reviewed. Sixty-three of these patients developed biochemical failure. These sixty-three patients were then matched in a one-to-one ratio to patients without biochemical failure, controlling for biopsy Gleason score, clinical stage, initial prostate-specific antigen, age, and the use of androgen deprivation. The pathology of the entire cohort was then reviewed for evidence of perineural invasion on initial prostate biopsy specimens. The biochemical relapse free survival rates for these two groups were compared.', 'Cases and controls were well matched, and there were no significant differences between the two groups in age, Gleason grade, clinical stage, initial prostate-specific antigen, and the use of androgen deprivation. PNI was found in 19 (17%) patients. There was no significant difference in the rates of PNI between cases and controls, 19.6% and 14.3% respectively (p = 0.45). PNI did not correlate with biochemical relapse free survival (p = 0.40).
Example Output:
Does perineural invasion on prostate needle biopsy predict biochemical failure following brachytherapy for prostate cancer?