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 Input:
Context: Pandemic strains of HIV-1 (group M) encode a total of nine structural (gag, pol, env), regulatory (rev, tat) and accessory (vif, vpr, vpu, nef) genes. However, some subtype A and C viruses exhibit an unusual gene arrangement in which the first exon of rev (rev1) and the vpu gene are placed in the same open reading frame. Although this rev1-vpu gene fusion is present in a considerable fraction of HIV-1 strains, its functional significance is unknown.', 'Examining infectious molecular clones (IMCs) of HIV-1 that encode the rev1-vpu polymorphism, we show that a fusion protein is expressed in infected cells. Due to the splicing pattern of viral mRNA, however, these same IMCs also express a regular Vpu protein, which is produced at much higher levels. To investigate the function of the fusion gene, we characterized isogenic IMC pairs differing only in their ability to express a Rev1-Vpu protein. Analysis in transfected HEK293T and infected CD4+ T cells showed that all of these viruses were equally active in known Vpu functions, such as down-modulation of CD4 or counteraction of tetherin. Furthermore, the polymorphism did not affect Vpu-mediated inhibition of NF-B activation or Rev-dependent nuclear export of incompletely spliced viral mRNAs. There was also no evidence for enhanced replication of Rev1-Vpu expressing viruses in primary PBMCs or ex vivo infected human lymphoid tissues. Finally, the frequency of HIV-1 quasispecies members that encoded a rev1-vpu fusion gene did not change in HIV-1 infected individuals over time.
Answer: Expression of a rev1-vpu fusion gene does not affect regular Rev and Vpu functions or alter HIV-1 replication in primary target cells. Since there is no evidence for increased replication fitness of rev1-vpu encoding viruses, this polymorphism likely emerged in the context of other mutations within and/or outside the rev1-vpu intergenic region, and may have a neutral phenotype.

Ex Output:
Does a Naturally Occurring rev1-vpu Fusion Gene Confer a Fitness Advantage to HIV-1?

Ex Input:
Context: Our previous studies suggested that brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) axis inhibited cardiomyocyte apoptosis in myocardial infarction (MI). However, the relationship between BDNF and microRNA (miRNA) in cardiomyocytes are unclear. The present study was performed to investigate the role of miR-195 and the interplay between BDNF and miR-195 in ischemic cardiomyocyte apoptosis.', 'Male Wistar rats were subjected to coronary artery ligation, and primary neonatal rat ventricular myocytes were treated with hypoxia or hydrogen peroxide (H2O2). BDNF level in rat ventricles was measured by enzyme linked immunosorbent assay (ELISA). miR-195 mimic, inhibitor or negative control was transfected into the cardiomyocytes. Cell viability and apoptosis were detected by MTT assay and TdT-mediated dUTP nick end labeling (TUNEL) staining, respectively. Cardiac function and apoptosis were detected in MI rats intravenously injected with antagomiR-195. Luciferase assay, Western blot and Real-time RT-PCR were employed to clarify the interplay between miR-195 and BDNF.', 'miR-195 level was dynamically regulated in response to MI and significantly increased in ischemic regions 24 h post-MI as well as in hypoxic or H2O2-treated cardiomyocytes. Meanwhile, BDNF protein level was rapidly increased in MI rats and H2O2-treated cardiomyocytes. Apoptosis in both hypoxic and H2O2-treated cardiomyocytes were markedly reduced and cell viability was increased by miR-195 inhibitor. Moreover, inhibition of miR-195 significantly improved cardiac function of MI rats. Bcl-2 but not BDNF was validated as the direct target of miR-195. Furthermore, BDNF abolished the pro-apoptotic role of miR-195, which was reversed by its scavenger TrkB-Fc.
Answer: Up-regulation of miR-195 in ischemic cardiomyocytes promotes ischemic apoptosis by targeting Bcl-2. BDNF mitigated the pro-apoptotic effect of miR-195 in rat cardiomyocytes. These findings may provide better understanding of the pro-apoptotic role of miR-195 in MI and suggest that BDNF/miR-195/Bcl-2 axis may be beneficial for limiting myocardial ischemic injury.

Ex Output:
Does bDNF-mediates Down-regulation of MicroRNA-195 inhibit Ischemic Cardiac Apoptosis in Rats?

Ex Input:
Context: We sought to investigate the effect of cardiac medication on long-term mortality in patients with peripheral arterial disease (PAD).', 'Peripheral arterial disease is associated with increased cardiovascular morbidity and mortality. Treatment guidelines recommend aggressive management of risk factors and lifestyle modifications. However, the potential benefit of cardiac medication in patients with PAD remains ill defined.', 'In this prospective observational cohort study, 2,420 consecutive patients (age, 64 +/- 11 years, 72% men) with PAD (ankle-brachial index < or =0.90) were screened for clinical risk factors and cardiac medication. Follow-up end point was death from any cause. Propensity scores for statins, beta-blockers, aspirin, angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers, diuretics, nitrates, coumarins, and digoxin were calculated. Cox regression models were used to analyze the relation between cardiac medication and long-term mortality.', 'Medical history included diabetes mellitus in 436 patients (18%), hypercholesterolemia in 581 (24%), smoking in 837 (35%), hypertension in 1,162 (48%), coronary artery disease in 1,065 (44%), and a history of heart failure in 214 (9%). Mean ankle-brachial index was 0.58 (+/-0.18). During a median follow-up of eight years, 1,067 patients (44%) died. After adjustment for risk factors and propensity scores, statins (hazard ratio [HR] 0.46, 95% confidence interval [CI] 0.36 to 0.58), beta-blockers (HR 0.68, 95% CI 0.58 to 0.80), aspirins (HR 0.72, 95% CI 0.61 to 0.84), and ACE inhibitors (HR 0.80, 95% CI 0.69 to 0.94) were significantly associated with a reduced risk of long-term mortality.
Answer: On the basis of this observational longitudinal study, statins, beta-blockers, aspirins, and ACE inhibitors are associated with a reduction in long-term mortality in patients with PAD.

Ex Output:
Is cardioprotective medication associated with improved survival in patients with peripheral arterial disease?