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.

[EX Q]: Context: Women have poorer outcomes after vascular surgery as compared to men as shown by studies recently. Frailty is also an independent risk factor for postoperative morbidity and mortality. This study examines the interplay of gender and frailty on outcomes after infrainguinal vascular procedures.', 'The American College of Surgeons National Surgical Quality Improvement Program database was used to identify all patients who underwent infrainguinal vascular procedures from 2005-2012. Frailty was measured using a modified frailty index (mFI; derived from the Canadian Study of Health and Aging). Univariate and multivariate analysis were performed to investigate the association of preoperative frailty and gender, on postoperative outcomes.', 'Of 24,645 patients (92% open, 8% endovascular), there were 533 deaths (2.2%) and 6198 (25.1%) major complications within 30 d postoperatively. Women were more frail (mean mFI = 0.269) than men (mean mFI = 0.259; P < 0.001). Women and frail patients (mFI>0.25) were more likely to have a major morbidity (P < 0.001) or mortality (P < 0.001) with the highest risk in frail women. On multivariate logistic regression analysis, female gender and increasing mFI were independently significantly associated with mortality (P < 0.05) as well as major complications. The interaction of gender and frailty in multivariate analysis showed the highest adjusted 30-d mortality and morbidity in frail females at 2.8% and 30.1%, respectively and that was significantly higher (P < 0.001) than nonfrail males, nonfrail females and frail males.
Answer: Female gender and frailty are both associated with increased risk of complications and death following infrainguinal vascular procedures with the highest risk in frail females. Further studies are needed to explore the mechanisms of interaction of gender and frailty and its effect on long-term outcomes for peripheral vascular disease.
[EX A]: Do gender and frailty predict poor outcomes in infrainguinal vascular surgery?

[EX Q]: Context: Cyclosporine causes intrarenal vasoconstriction, which may account for its nephrotoxic side effects. Plasma levels of the vasoconstrictor peptide endothelin-1 are increased after cyclosporine administration, and endothelin-1 has been shown to cause renal vasoconstriction. In this study we used in vivo microscopy to investigate the role of endothelin-1 in cyclosporine-induced vasoconstriction.', 'Hydronephrotic kidneys in decerebrate rats were suspended in an environmentally controlled tissue bath with neurovascular supply intact. Interlobular, afferent, and efferent arteriolar diameters and flow were measured by videomicroscopy and Doppler velocimetry. Cyclosporine was added to the tissue bath, and measurements were repeated for 60 minutes. In study groups endogenous endothelin-1 was blocked by infusion of either specific endothelin antiserum or an endothelin-1 receptor antagonist.', 'Cyclosporine caused constriction of the interlobular artery by 20% +/- 2% and a corresponding decrease in blood flow by 66% +/- 4%. The afferent and efferent arterioles constricted to a similar degree. This vasoconstriction was entirely prevented by infusion of either the endothelin antiserum or the receptor antagonist. The antagonist reagents alone had no effect on hemodynamic parameters or renal microvessel diameters.
Answer: The acute renal vasoconstriction induced by cyclosporine is mediated by endothelin-1. Endogenous endothelin-1 has little role in maintaining basal vascular tone.
[EX A]: Is acute cyclosporine-induced renal vasoconstriction mediated by endothelin-1?

[EX Q]: Context: Increased oxidative stress is associated with coronary heart disease (CHD). We examined the association between plasma markers of oxidative stress and CHD in a cross-sectional sample of patients with diabetes and prospective CHD risk in a sample of men predominantly without diabetes.', 'Plasma total antioxidant status (TAOS) and the ratio of oxidized LDL (Ox-LDL) to LDL-cholesterol (LDL-C) were determined in a cross-section of 761 Caucasian individuals with diabetes (UDACS study). Plasma TAOS was also determined in 310 baseline samples from a 10-year prospective cohort of 3012 healthy males (NPHSII).', 'Within UDACS, males with CHD had lower mean (SD) plasma TAOS [no CHD, 43.4 (13.2)%; CHD, 40.3 (13.8)%; P = 0.04]. The prevalence of CHD was higher in the lowest compared with the upper quartiles (32.7% vs 19.7%; P = 0.004). We observed a significant association between plasma Ox-LDL:LDL-C and CHD status [no CHD vs CHD, 16.9 (3.1) vs 19.3 (5.0) units/mmol; P = 0.04], with the prevalence of CHD being higher among men in the upper compared with lower quartiles (18.4% vs 35.1%; P = 0.003). No association was observed in females. In NPHSII, TAOS was lower in those who developed CHD [35.1 (8.0)% vs 37.1 (7.9)%; P = 0.04]. The odds ratio for CHD in the lowest compared with the upper quartile was 1.91 (95% confidence interval, 0.99-3.70; P = 0.04). This remained unchanged after adjustment for classic risk factors.
Answer: A cross-sectional and prospective association exists between baseline plasma measures of oxidative stress and CHD risk. The association with prospective CHD risk remained after adjustment for "traditional" risk factors, implying an independent role for oxidative stress in CHD risk.
[EX A]:
Are increased plasma markers of oxidative stress associated with coronary heart disease in males with diabetes mellitus and with 10-year risk in a prospective sample of males?