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.

Context: After ingestion of phosphatidylcholine, l-carnitine or betaine, trimethylamine-N-oxide (TMAO) is formed by gut microbiota and liver enzymes. Elevated TMAO plasma levels were associated with increased cardiovascular risk and other diseases. Also betaine and choline itself were recently associated with increased cardiovascular risk.', 'A newly developed LC-HRMS method was applied to measure the plasma concentrations of TMAO, betaine and choline in a cohort of 339 patients undergoing coronary angiography for the evaluation of suspected coronary artery disease.', "Betaine concentrations in males were significantly higher than in females (42.0 vs. 35.9mol/L; p<0.001). Plasma concentrations of TMAO but not of betaine or choline were higher in patients with diabetes compared to euglycemic patients (2.39 vs. 0.980mol/L; p=0.001) as well as in patients with metabolic syndrome as compared to patients without metabolic syndrome (2.37 vs. 1.43mol/L; p=0.002). Plasma concentrations of TMAO or choline increased significantly with decreasing renal function (Spearman's rho:-0.281; p<0.001). However, plasma levels of TMAO or betaine were associated with neither a history of myocardial infarction nor the angiographically assessed presence of coronary heart disease, nor incident cardiovascular events during 8 years of follow-up. Plasma levels of choline were significantly lower in patients with a history of acute myocardial infarction as compared to those without such history (10.0 vs. 10.8mol/L; p=0.045).
Answer: Plasma levels of TMAO are confounded by impaired kidney function and poor metabolic control but are not associated with the history, presence or incidence of symptoms or events of coronary heart disease.
Are plasma levels of trimethylamine-N-oxide confounded by impaired kidney function and poor metabolic control?

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

Context: Compared with standard donors, kidneys recovered from donors after cardiac death (DCD) exhibit higher rates of delayed graft function (DGF), and DCD livers demonstrate higher rates of biliary ischemia, graft loss, and worse patient survival. Current practice limits the use of these organs based on time from donor extubation to asystole, but data to support this is incomplete. We hypothesized that donor postextubation parameters, including duration and severity of hemodynamic instability or hypoxia might be a better predictor of subsequent graft function.', 'We performed a retrospective examination of the New England Organ Bank DCD database, concentrating on donor factors including vital signs after withdrawal of support.', 'Prolonged, severe hypotension in the postextubation period was a better predictor of subsequent organ function that time from extubation to asystole. For DCD kidneys, this manifested as a trend toward increased DGF. For DCD livers, this manifested as increased rates of poor outcomes. Maximizing the predictive value of this test in the liver cohort suggested that greater than 15 min between the time when the donor systolic blood pressure drops below 50 mm Hg and flush correlates with increased rates of diffuse biliary ischemia, graft loss, or death. Donor age also correlated with worse outcome.
Answer: Time between profound instability and cold perfusion is a better predictor of outcome than time from extubation to asystole. If validated, this information could be used to predict DGF after DCD renal transplant and improve outcomes after DCD liver transplant.
Do donor postextubation hypotension and age correlate with outcome after donation after cardiac death transplantation?