In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: Allergic asthma is characterized by inflammation and airway remodeling. Bronchial epithelium is considered a key player in coordinating airway wall remodeling. In mild asthma, the epithelium is damaged and fails to proliferate and to repair, whereas in severe asthma, the epithelium is highly proliferative and thicker. This may be due to different regulatory mechanisms. The purpose of our study was to determine the role of miRNAs in regulating proliferation of bronchial epithelial cells obtained from severe asthmatic subjects in comparison with cells obtained from mild asthmatics and healthy controls.', 'Human bronchial epithelial cells (BEC) were isolated by bronchoscopy from bronchial biopsies of healthy donors and patients with mild and severe asthma. MiRNA expression was evaluated using the TaqMan low-density arrays and qRT-PCR. Transfection studies of bronchial epithelial cells were performed to determine the target genes. Cell proliferation was evaluated by BrdU incorporation test.', 'MiR-19a was upregulated in epithelia of severe asthmatic subjects compared with cells from mild asthmatics and healthy controls. Functional studies based on luciferase reporter and Western blot assays suggest that miR-19a enhances cell proliferation of BEC in severe asthma through targeting TGF-β receptor 2 mRNA. Moreover, repressed expression of miR-19a increased SMAD3 phosphorylation through TGF-β receptor 2 signaling and abrogated BEC proliferation.\Question: Does microRNA-19a enhance proliferation of bronchial epithelial cells by targeting TGFβR2 gene in severe asthma?
Our study uncovers a new regulatory pathway involving miR-19a that is critical to the severe phenotype of asthma and indicates that downregulating miR-19a expression could be explored as a potential new therapy to modulate epithelium repair in asthma.

Context: The blasticidin S resistance gene (bsr) is a selectable marker used for gene transfer experiments. The bsr gene encodes for blasticidin S (BS) deaminase, which has a specific activity upon BS. Therefore, its expression is supposed to be harmless in cells. The work reported on herein consisted of experiments to verify a possible toxicity of bsr on mammalian cells, which include several cell lines and primary cultures.', 'Murine keratinocyte BALB/MK and human primary keratinocyte cells transduced with the retroviral vector LBmSN, which has an improved expression system of bsr, namely bsrm, died in five days after the transduction. Meanwhile the control vector LBSN, which expresses bsr, did not provoke cell death. The lethal activity of bsrm was observed only in human keratinocytes and BALB/MK cells among the cell types tested here. Death appears to be mediated by a factor, which is secreted by the BALB/MK transduced cells.\Question: Is over expression of the selectable marker blasticidin S deaminase gene toxic to human keratinocytes and murine BALB/MK cells?
By our study we demonstrated that the expression of bsrm gene is toxic to human keratinocytes and BALB/MK cells. It is likely over expression of BS deaminase gene is responsible for the death.

Context: This study evaluates whether depression is a risk factor for incident myocardial infarction (MI) in Department of Veterans Affairs (VA) patients with rheumatoid arthritis (RA) between 30 and 79 years of age.', 'We used a retrospective cohort study of 15,634 patients with RA. Diagnoses and sociodemographic data were obtained from VA administrative and pharmacy databases between fiscal years 1999 and 2006. Entry into the cohort required 2 years of patient time with no evidence of cardiovascular disease. Cox proportional hazard models with time-dependent covariates were computed to determine whether RA patients with depression as compared to RA patients without depression were at increased risk for MI during the maximum 6-year follow-up period.', 'Unadjusted analyses indicated depressed RA patients were 1.4 times more likely than nondepressed RA patients to have an MI during follow-up. These results remained significant (HR=1.4; 95% CI: 1.1-1.8) in the adjusted Cox proportional hazards model which included the effects of sociodemographics and known physical risks (e.g., diabetes) for MI.\Question: Does depression increase risk of incident myocardial infarction among Veterans Administration patients with rheumatoid arthritis?

Depressed RA patients, without a history of cardiovascular disease, are 40% more likely to have a heart attack as compared to those without depression. These data demonstrate a rapid (within 6 years) transition to MI following onset of depression in RA patients. Increased monitoring of depression and heart disease status in this patient population may be warranted which in turn may result in longer duration of life.