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 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.
Answer: In this series, increased LVMPI correlated with biopsy-proven rejection, and frequent serial assessments using this technique may provide a relatively sensitive non-invasive means of rejection surveillance after pediatric cardiac transplantation. False positive results may be encountered, likely due to alterations in diastolic function that have been previously observed in transplant recipients.
[EX A]: Does increased myocardial performance index correlate with biopsy-proven rejection in pediatric heart transplant recipients?

[EX Q]: Context: The aim of the current study was to test the impact of dentin powder on the antimicrobial efficacy of bioactive glass S53P4 (BAG).', 'BAG was suspended (preincubated) in saline at 37 degrees C for different time periods with or without human dentin powder, hydroxylapatite, or decalcified dentin. Subsequently, Enterococcus faecalis ATCC 29212 cells were added to these suspensions and bacterial recovery measured with and without the use of gentle sonication. Furthermore, survival of bacteria in test and control suspensions was assessed over time. Supernatants of suspensions were analyzed for their element contents using atomic absorption spectrophotometry. The effects of pH, silica, and osmolarity on E faecalis viability were assessed using specifically prepared solutions.', 'BAG preincubated with dentin powder caused a significant (P < .05) decrease in viability compared to pure BAG suspensions. This was not based on adherence of bacteria to solid particles or agglutination of the cells, because sonication did not increase bacterial yields. Hydroxylapatite and decalcified dentin did not increase BAG killing efficacy. The additive effect of BAG + dentin powder was dose dependent, occurred only with solids in suspension, and increased with suspension time. An augmented dissolution of glass components, especially silicon, was measured in BAG + dentin powder compared to pure BAG suspensions or counterparts containing hydroxylapatite or decalcified dentin. High osmolarity per se did not affect E faecalis viability, whereas high pH and silica levels did.
Answer: The observed phenomenon was related to an increased BAG dissolution triggered by dentin powder, causing elevated local pH and silica levels.
[EX A]: Does dentin enhance the effectiveness of bioactive glass S53P4 against a strain of Enterococcus faecalis?

[EX Q]: Context: The aim of this study was to examine the growth arrest and DNA damage-inducible (Gadd45a) expression and its role in tumor progression, invasion and metastasis in oral squamous cell carcinoma (OSCC).', 'Growth arrest and DNA damage-inducible 45a distribution was detected by immunohistochemistry in tumor sections of 106 patients with primary OSCC and sections of adjacent pericancerous tissues from 60 patients among the 106. The association between the Gadd45a expression and clinical prognosis of OSCC were performed by statistical analysis. Gadd45a gene knockdown was performed in Tca8113 cells by small interfering ribonucleic acid treatment and its effects on cell cycle, and migration were detected by Flow Cytometric (Becton Dickinson, USA) and transwell chamber assay respectively.
Answer: The results showed that Gadd45a was redistributed to cytoplasm in poorly differentiated carcinoma from its nucleus location in normal tissue (P < 0.05). The expression of Gadd45a was significantly associated with lymph node metastasis, tumor stage and tumor histological grade (P < 0.05). Knockdown of Gadd45a gene abolished the G2/M arrest and increased migrating ability of Tca8113 cell (P < 0.05). The results indicate that Gadd45a play an important role in OSCC metastasis by affecting the bioactivity of the tumor cells, and its distribution may serve for the prediction of clinical outcome of OSCC.
[EX A]:
Is expression of growth arrest and DNA damage inducible 45a in human oral squamous cell carcinoma associated with tumor progression and clinical outcome?