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.

Input: Consider Input: Context: Therapeutic and prophylactic vena cava filters (VCFs) are used to prevent pulmonary embolism. Concerns exist over placing a permanent filter in a young trauma patient. Recently, retrievable VCFs have become available. One such filter is the OptEase, which has a recommended time of removal of up to 23 days after insertion. Data supporting this recommendation are sparse. Many trauma patients will need filters for more than 2 weeks, and there are no data evaluating the safety of removal after extended time periods. The purpose of this study was to determine the safety, feasibility, and reaction of the vena cava when removing the OptEase retrievable VCF at different time intervals.', 'Twenty Yorkshire cross pigs (80-113 kg) underwent general anesthesia with tiletamine and zolazepam. Filters were placed in the infrarenal vena cava (VC) through the femoral vein under fluoroscopic guidance. Animals were then divided into four groups. In group 1, filters were removed at 14 days; in group 2, at 30 days; in group 3, at 60 days; and in group 4, at 90 days. Removal was attempted using a snare-and-sheath technique through the femoral vein. Animals with successful filter removal were allowed to recover; then, the animals underwent autopsy (gross and microscopic VC examination) 2 months later. Animals with unsuccessful filter removal underwent autopsy immediately after attempted removal. Venacavograms were taken at filter insertion, at removal, and before autopsy to evaluate any VC abnormalities.', 'Successful removal of the filter in all five pigs (100%) was reliably performed only in the 14-day group. In this group, the initial VC transverse diameter was 19.4 +/- 0.8 mm and was significantly reduced to 9.8 +/- 1.1 mm (p < 0.05) immediately after removal. Sixty days later, before autopsy, VC diameter had increased to 15.3 +/- 1.9 mm, which was significantly larger than at removal (p < 0.05) but not different from the initial value. In the 30-day group, removal was successful in only one of five animals. Although removal was successful in the one pig, autopsy at 2 months postremoval revealed total occlusion of the VC. Filters could not be removed from 60- and 90-day groups. At autopsy, the VCF struts were embedded or protruded through the VC wall. Microscopic examination of the VC revealed significant scarring underneath and between the struts.\Question: Is removal of the OptEase retrievable vena cava filter feasible after extended time periods because of filter protrusion through the vena cava?

Output: Removal of the retrievable OptEase VCF may be successfully performed up to 14 days after insertion. Strut protrusion through the VC wall prohibited successful and safe removal at extended time intervals.

Input: Consider Input: Context: B-type natriuretic peptide (BNP) correlates with cardiac filling pressures and outcomes in patients with heart failure. In heart transplant recipients, we hypothesize that a within-individual change in BNP over time would be more helpful than absolute BNP in detecting International Society of Heart and Lung Transplantation (ISHLT) grade 2R or greater rejection.', 'N-terminal pro-BNP (NT-proBNP) levels were measured in 146 consecutive transplant recipients undergoing routine endomyocardial biopsies. In the cross-sectional analysis, multiple observations per individual were accounted for using generalized estimation equations.', "A cross-sectional analysis demonstrated a weak association between NT-proBNP levels and rejection, with an odds ratio (OR) of 1.01 for every 100-pg/mL increase in NT-proBNP (p = 0.02). However, with a doubling of an individual's NT-proBNP level, the OR for significant rejection was 2.9 (95% confidence interval [CI] 1.2-7.0), the OR with a 5-fold increase was 9.1 (95% CI, 2.7-31.5), and the OR with a 10-fold increase was 27.7 (95% CI, 5.9-129). A 10-fold increase in NT-proBNP offered a negative predictive value of 95% for the diagnosis of rejection. The relationship between within-individual increases in NT-proBNP and rejection persisted after adjusting for a fall in ejection fraction and a rise pulmonary capillary wedge pressure, and was a stronger predictor than changes in these parameters.\Question: Does the change in B-type natriuretic peptide levels over time predict significant rejection in cardiac transplant recipients?

Output: There is a strong, graded relationship between the within-individual increase in NT-proBNP and the odds of significant rejection independent of hemodynamic parameters. These results suggest that the change in NT-proBNP rather than absolute BNP levels may offer a non-invasive approach to detect rejection.

Input: Consider Input: Context: Asthma is characterized by airway inflammation and remodelling in which matrix metalloproteinases (MMPs) play an important role. MMP-9 is the major MMP found in the bronchoalveolar lavage fluids and bronchial biopsies from patients with allergic asthma after allergen challenge, where it correlates with the count of neutrophils and macrophages. However, the cellular sources of MMP-9 in this inflammatory condition have not yet been clearly identified. This work was undertaken to analyse whether neutrophils may be a source of MMP-9 in the allergic asthma condition upon allergen challenge.', 'Neutrophils from allergic asthmatic patients were invitro stimulated, and the levels of MMP-9 release were measured in the cell culture supernatants using enzyme-linked immunosorbent assay (ELISA) and zymography.', 'We show that MMP-9 is released by neutrophils, but not by eosinophils from allergic asthmatic patients in response to allergens to which the patients were sensitized. Neutrophils also released MMP-9 in response to anti-IgE Abs, and agonist Abs against FcRI, FcRII/CD23 and galectin-3. Inhibitors of transcription and translation, actinomycin D and cycloheximide, partially cancelled this process, suggesting that MMP-9 is also de novo synthesized in response to stimuli. We also show evidence that the MAPKs, p38 and extracellular signal-regulated kinase, as well as the transcription factor NF-B, are involved, as specific chemical inhibitors of these cell-signalling pathways abolished the anti-IgE/allergen-dependent MMP-9 release.\Question: Do neutrophils from allergic asthmatic patients produce and release metalloproteinase-9 upon direct exposure to allergens?
Output: These data demonstrate that the exposure of neutrophils to allergens leads to generation of MMP-9, which may then lead to remodelling in asthma.