TASK DEFINITION: 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.
PROBLEM: Context: Prostaglandin D2 (PGD2) and cysteinyl leukotrienes (cysLTs) are lipid mediators derived from mast cells, which activate TH2 cells. The combination of PGD2 and cysLTs (notably cysteinyl leukotriene E4 [LTE4]) enhances TH2 cytokine production. However, the synergistic interaction of cysLTs with PGD2 in promoting TH2 cell activation is still poorly understood. The receptors for these mediators are drug targets in the treatment of allergic diseases, and hence understanding their interaction is likely to have clinical implications.', 'We aimed to comprehensively define the roles of PGD2, LTE4, and their combination in activating human TH2 cells and how such activation might allow the TH2 cells to engage downstream effectors, such as neutrophils, which contribute to the pathology of allergic responses.', 'The effects of PGD2, LTE4, and their combination on human TH2 cell gene expression were defined by using a microarray, and changes in specific inflammatory pathways were confirmed by means of PCR array, quantitative RT-PCR, ELISA, Luminex, flow cytometry, and functional assays, including analysis of downstream neutrophil activation. Blockade of PGD2 and LTE4 was tested by using TM30089, an antagonist of chemoattractant receptor-homologous molecule expressed on TH2 cells, and montelukast, an antagonist of cysteinyl leukotriene receptor 1.', 'PGD2 and LTE4 altered the transcription of a wide range of genes and induced diverse functional responses in TH2 cells, including cell adhesion, migration, and survival and cytokine production. The combination of these lipids synergistically or additively enhanced TH2 responses and, strikingly, induced marked production of diverse nonclassical TH2 inflammatory mediators, including IL-22, IL-8, and GM-CSF, at concentrations sufficient to affect neutrophil activation.
Answer: PGD2 and LTE4 activate TH2 cells through different pathways but act synergistically to promote multiple downstream effector functions, including neutrophil migration and survival. Combined inhibition of both PGD2 and LTE4 pathways might provide an effective therapeutic strategy for allergic responses, particularly those involving interaction between TH2 cells and neutrophils, such as in patients with severe asthma.

SOLUTION: Do prostaglandin D2 and leukotriene E4 synergize to stimulate diverse TH2 functions and TH2 cell/neutrophil crosstalk?

PROBLEM: 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.

SOLUTION: Does dentin enhance the effectiveness of bioactive glass S53P4 against a strain of Enterococcus faecalis?

PROBLEM: Context: The prognosis of patients with severe aortic stenosis, low aortic gradient and preserved ejection fraction is controversial. Our study analyzed the prognosis of these patients and its relation to pressure gradient and aortic valve flow.', 'We performed a retrospective cohort study of 363 consecutive patients with severe aortic stenosis and preserved ejection fraction, divided into 4 groups, based on the presence of a systolic volume index greater or lower than 35 mL/m(2) and the presence of a mean aortic gradient greater or lower than 40 mmHg. Group I: normal flow, high gradient (n=169, 47%); group II: normal flow, low gradient (n=98, 27%); group III: low flow, high gradient (n=54, 15%), and group IV: low flow, low gradient (n=42, 12%). The primary endpoint was overall mortality.', 'Independent risk factors for mortality were age (hazard ratio=1.04; 95% confidence interval, 1.01-1.08) and atrial fibrillation (hazard ratio=2.21; 95% confidence interval, 1.24-3.94). Surgical treatment was associated with longer survival in all groups (hazard ratio=0.25; 95% confidence interval: 0.13-0.49). Mortality was higher in patients with low flow than in those with with normal flow (26.6% vs 13.6%; P=.004). The most favorable mean prognosis was found in group II (hazard ratio=0.4; 95% confidence interval, 0.2-0.9).
Answer: Patients with severe aortic stenosis, normal ejection fraction and low aortic flow have a worse prognosis. Analysis of aortic flow by Doppler echocardiography is useful in risk stratification and therapeutic decision-making in patients with aortic stenosis.

SOLUTION:
Is systolic volume index by Doppler echocardiography an useful marker for stratification and prognostic evaluation in patients with severe aortic stenosis and preserved ejection fraction?