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.
--------
Question: Context: Severe mitral regurgitation (MR) reduces left atrial thrombus formation in patients with mitral stenosis (MS) and atrial fibrillation (AF). Plasma D-dimer levels represent a biochemical marker for fibrinolytic activity in prothrombotic states. The prothrombotic burden in patients with mitral valve disease and/or AF was assessed using plasma D-dimer levels.', 'The study population included 89 patients with mitral valve disease, 21 with AF but normal valves, and 15 healthy controls. The mitral valve group was subdivided into patients with MS (n = 27), severe MR (n = 26), and MS with concomitant with severe MR (MS/MR; n = 36). These subgroups were further subdivided according to the atrial rhythm (sinus rhythm (SR)+AF).', 'The mean left atrial size was increased in all groups with cardiac disease. D-dimer levels were highest in the MS+AF subgroup (527 +/- 134 microg/l). Patients with MS+AF, MS+SR, and nonvalvular AF had significantly higher D-dimer levels than controls (p < 0.01, by ANOVA). Patients with MR had normal levels of D-dimer. The atrial rhythm did not influence D-dimer levels in the MS/MR subgroup, or in the pure MR subgroup (p = NS).
Answer: Plasma D-dimer levels correlated with the embolic risk in mitral valve disease and non-valvular AF. The highest levels were found in patients with MS+AF and non-valvular AF. Severe MR decreased the D-dimer levels in MS and/or AF to control levels.

Answer: Does mitral regurgitation reduce systemic coagulation activity in patients with rheumatic heart disease?


Question: Context: Bone marrow stromal cell antigen 2 (BST2), also known as tetherin, HM1.24 or CD317 represents a type 2 integral membrane protein, which has been described to restrict the production of some enveloped viruses by inhibiting the virus release from the cell surface. This innate antiviral mechanism is counteracted by the HIV-1 viral factor Vpu, targeting BST2 for cellular degradation. Since antiviral BST2 activity has been mainly confirmed by in vitro data, we investigated its role in vivo on the disease progression using the SIV/macaque model for AIDS. We determined BST2 expression in PBMC and leukocyte subsets of uninfected and SIV-infected rhesus macaques by real-time PCR and flow cytometry and correlated it with disease progression and viral load.', 'Compared to pre-infection levels, we found increased BST2 expression in PBMC, purified CD4(+) lymphocytes and CD14(+) monocytes of SIV-infected animals, which correlated with viral load. Highest BST2 levels were found in progressors and lowest levels comparable to uninfected macaques were observed in long-term non-progressors (LTNPs). During acute viremia, BST2 mRNA increased in parallel with MX1, a prototype interferon-stimulated gene. This association was maintained during the whole disease course.
Answer: The detected relationship between BST2 expression and viral load as well as with MX1 indicate a common regulation by the interferon response and suggest rather limited influence of BST2 in vivo on the disease outcome.

Answer: Is increased BST2 expression during simian immunodeficiency virus infection a determinant of disease progression in rhesus monkeys?


Question: Context: Based on the data from elective surgical patients, positioning patients in a back-up head-elevated position for preoxygenation and tracheal intubation can improve patient safety. However, data specific to the emergent setting are lacking. We hypothesized that back-up head-elevated positioning would be associated with a decrease in complications related to tracheal intubation in the emergency room environment.', 'This retrospective study was approved by the University of Washington Human Subjects Division (Seattle, WA). Eligible patients included all adults undergoing emergent tracheal intubation outside of the operating room by the anesthesiology-based airway service at 2 university-affiliated teaching hospitals. All intubations were through direct laryngoscopy for an indication other than full cardiopulmonary arrest. Patient characteristics and details of the intubation procedure were derived from the medical record. The primary study endpoint was the occurrence of a composite of any intubation-related complication: difficult intubation, hypoxemia, esophageal intubation, or pulmonary aspiration. Multivariable logistic regression was used to estimate the odds of the primary endpoint in the supine versus back-up head-elevated positions with adjustment for a priori-defined potential confounders (body mass index and a difficult intubation prediction score [Mallampati, obstructive sleep Apnea, Cervical mobility, mouth Opening, Coma, severe Hypoxemia, and intubation by a non-Anesthesiologist score]).', 'Five hundred twenty-eight patients were analyzed. Overall, at least 1 intubation-related complication occurred in 76 of 336 (22.6%) patients managed in the supine position compared with 18 of 192 (9.3%) patients managed in the back-up head-elevated position. After adjusting for body mass index and the Mallampati, obstructive sleep Apnea, Cervical mobility, mouth Opening, Coma, severe Hypoxemia, and intubation by a non-Anesthesiologist score, the odds of encountering the primary endpoint during an emergency tracheal intubation in a back-up head-elevated position was 0.47 (95% confidence interval, 0.26-0.83; P = 0.01).
Answer: Placing patients in a back-up head-elevated position, compared with supine position, during emergency tracheal intubation was associated with a reduced odds of airway-related complications.

Answer:
Does head-Elevated Patient Positioning decrease Complications of Emergent Tracheal Intubation in the Ward and Intensive Care Unit?