instruction:
Given a passage, 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:
Changes of volume status can be readily inferred from variations in diameter of the inferior vena cava (IVC) measured by ultrasound. However the effect of IVC changes following acute blood loss are not fully established. In this study, three different approaches to measuring IVC variables were compared in healthy blood donors, as a model of acute volume depletion, in order to establish their relative ability to detect acute blood loss.', 'Inspiratory and expiratory IVC diameters were measured before and after blood donation in hepatic long axis, hepatic short axis and renal short axis views using a 2-5\xa0MHz curvilinear probe. All measurements were recorded and examined in real-time and post-processing sessions.', 'All windows performed satisfactorily but the renal window approach was feasible in only 30 out of 47 subjects. After blood donation, IVC diameters decreased in hepatic long axis, hepatic short axis and renal short axis (expiratory: -19.9, -18.0, -26.5\xa0%; CI 95\xa0%: 14.5-24.1; 13.1-22.9; 16.0-35.9, respectively) (inspiratory: -31.1, -31.6, -36.5\xa0%; CI 95\xa0%: 21.3-40.1; 18.8-45.2; 23.4-46.0, respectively), whereas the IVC collapsibility index increased by 21.6, 22.6 and 19.3\xa0% (CI 95\xa0%: 11.6-42.9; 18.5-39.5; 7.7-30.0). IVC diameters appeared to return to pre-donation values within 20\xa0min but this was only detected by the hepatic long axis view.
answer:
Do inferior vena cava diameters and collapsibility index reveal early volume depletion in a blood donor model?


question:
The tumor necrosis factor (TNF) gene is located within the highly polymorphic major histocompatibility complex region, exhibiting the -308 GA promoter region polymorphism and six microsatellites (TNFa-f) spanning the region nearby the TNF locus.', 'In the present study, we evaluated the frequency of -308 GA and TNFa-e polymorphisms and respective haplotypes (in chromosomal sequence: TNFd-TNFe-308GA-TNFc-TNFa-TNFb), in 222 patients with AIDS, 52 of whom exhibited cytomegalovirus retinitis, and in 202 healthy HIV-negative individuals.', 'TNF microsatellite and single nucleotide polymorphism typings were performed by PCR followed by polyacrylamide gel electrophoresis.', 'The TNF-308A allele and the 4-3-G-2-7-1 haplotype were associated with susceptibility to AIDS, whereas the TNFb4 allele and the 3-3-G-1-11-4 haplotype were associated with protection against AIDS development. The TNFc2 allele and the 4-1-G-2-2-1 haplotype, which contains the TNFc2 allele, were associated with cytomegalovirus retinitis.
answer:
Are tumor necrosis factor region polymorphisms associated with AIDS and with cytomegalovirus retinitis?


question:
Arterial age can be estimated from equations relating arterial stiffness to age and blood pressure in large cohorts. We investigated whether estimated arterial age (eAA) was elevated in patients with the metabolic syndrome and/or known cardiovascular disease (CVD), which factors were associated with eAA and whether eAA added prognostic information.', 'In 1993, 2366 study participants, 41, 51, 61, and 71 years old, had traditional cardiovascular risk factors and carotid-femoral pulse wave velocity (cfPWV) measured. Risk groups were identified based on known CVD and components of metabolic syndrome, Systematic COronary Risk Evaluation, or Framingham risk score. From age, mean blood pressure, and cfPWV, eAA and estimated cfPWV (ePWV) were calculated. In 2006, the combined cardiovascular endpoint (CEP) of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, and hospitalization for ischemic heart disease was registered.', 'cfPWV and ePWV increased with ageing and cardiovascular risk (all P\u200a<\u200a0.001), but ePWV increased more with ageing than cfPWV. The difference between eAA and chronological age was associated with male sex (β\u200a=\u200a0.14), higher heart rate (β\u200a=\u200a0.16 both P\u200a<\u200a0.001), fasting glucose (β\u200a=\u200a0.08) soluble urokinase plasminogen activator receptor (β\u200a=\u200a0.06, both P\u200a<\u200a0.01), and known CVD (β\u200a=\u200a0.06, P\u200a<\u200a0.05) independently of age, SBP, and heart rate. Independently of Systematic COronary Risk Evaluation, eAA (hazard ratio\u200a=\u200a1.20, P\u200a<\u200a0.01) predicted CEP, but not as accurately as ePWV (hazard ratio\u200a=\u200a1.58, P\u200a<\u200a0.001) and cfPWV (hazard ratio\u200a=\u200a1.32, P\u200a<\u200a0.001) among apparently healthy study participants.
answer:

Is elevated estimated arterial age associated with metabolic syndrome and low-grade inflammation?