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:
Class III antiarrhythmic agents exhibit reverse rate-dependent lengthening of the action potential duration (APD). In spite of the several theories developed so far to explain this reverse rate dependency (RRD), its mechanism has not yet been clarified. The aim of the present work was to further elucidate the mechanisms responsible for reverse rate-dependent drug effects.', 'Action potentials were recorded from multicellular canine ventricular preparations and isolated cardiomyocytes, at cycle lengths (CLs) varying from 0.3 to 5 s, using conventional sharp microelectrodes. APD was either modified by applying inward and outward current pulses, or by superfusion of agents known to lengthen and shorten APD. Net membrane current (I(m)) was calculated from action potential waveforms. The hypothesis that RRD may be implicit in the relationship between I(m) and APD was tested by numerical modelling. Both drug-induced lengthening (by veratrine, BAY-K 8644, dofetilide, and BaCl(2)) and shortening (by lidocaine and nicorandil) of action potentials displayed RRD, i.e. changes in APD were greater at longer than at shorter CL. A similar dependency of effect on CL was found when repolarization was modified by injection of inward or outward current pulses. I(m) measured at various points during repolarization was inversely proportional to APD and to CL. Model simulations showed that RRD is expected as a consequence of the non-linearity of the relationship between I(m) and APD.
answer:
Is reverse rate dependency an intrinsic property of canine cardiac preparations?


question:
Obstructive sleep apnea (OSA) is a common disorder characterized by chronic intermittent hypoxia (CIH). OSA is prevalent in obese subjects and is associated with endothelial dysfunction and cardiovascular disorders. We tested the hypothesis that the deleterious effects of IH could be further modulated by diet-induced obesity.', 'Thirty adult (8-10 weeks) male C57BL/6J mice were divided into four groups. Mice were subjected to CIH or intermittent air (IA) for 12h a day and fed either a high fat (HF) or a low fat control diet (CD) for 6weeks. We analyzed endothelial function using a wire myograph, and measured markers of oxidative stress (plasma malondialdehyde (MDA) and total antioxidant capacity (TAC)) using colorimetrical assays. We also measured C-reactive protein (CRP) using ELISA and endothelial nitric oxide (eNOS) gene expression using real time PCR.', 'Stimulated endothelial dependent dilation was significantly impaired only in the group fed high fat diet and subjected to CIH (Emax: HFIH 78±2%, p<0.0001) when compared to the other groups (Emax: HFIA 95±0.7%, CDIH 94±2%, CDIA 97±1%). Also basal endothelial dependant dilation was attenuated in the HFIH group compared to the HFIA group (Emax: HFIH: 179±10% vs. HFIA: 149±11% in the presence of L-NAME). Levels of MDA were elevated in the CDIH group when compared to CDIA (0.68±0.04 vs. 0.41±0.03 μM, p<0.05) but were greatest in the HFIH group (0.83±0.08 μM, p<0.05). However, there was no significant increase in MDA levels in the HFIA group (0.45±0.03 μM, p=NS) when compared to all other groups. Similar effects were observed with CRP levels; CRP levels were significantly higher in the CDIH group compared with intermittent air (10.39±0.38 vs. 8.70±0.21 μg/ml, p<0.05) but the HFIH had the greatest levels of CRP (11.87±0.31 μg/ml, p<0.05). In the HFIA group, CRP levels were not elevated (9.96±0.37 μg/ml, p=NS). Nevertheless, total antioxidant capacity and eNOS gene expression were not significantly different in the groups.
answer:
Does chronic intermittent hypoxia cause endothelial dysfunction in a mouse model of diet-induced obesity?


question:
To determine if early pregnancy serum biomarkers in high-risk women who develop preeclampsia vary according to risk factor.', 'We performed a secondary analysis of the Maternal-Fetal Medicine Units Network randomized controlled trial of low-dose aspirin for the prevention of preeclampsia in high-risk women. Serum biomarker levels at enrollment (before initiation of aspirin or placebo) were compared between women who did and did not develop preeclampsia, both for the group as a whole and within each of 4 high-risk groups (insulin-dependent diabetes, hypertension, multiple gestation, and previous preeclampsia) using a regression model adjusting for gestational age at collection and prepregnancy body mass index.', '1258 women were included (233 with insulin-dependent diabetes, 387 with chronic hypertension, 315 with a multiple gestation, 323 with previous preeclampsia). Multiple early pregnancy serum biomarkers differed between women who did and did not develop preeclampsia. Each high-risk group had a unique and largely nonoverlapping pattern of biomarker abnormality. Differences between those who did and did not develop preeclampsia were noted in vascular cell adhesion molecule in the diabetes group; human chorionic gonadotropin, soluble tumor necrosis factor receptor-2, tumor necrosis factor-alpha, selectin and angiogenin in the chronic hypertension group; interleukin-6, placental growth factor, soluble fms-like tyrosine kinase plus endoglin to placental growth factor ratio in the multiple gestation group; and angiogenin in the previous preeclampsia group.
answer:

Is preeclampsia in high risk women characterized by risk group-specific abnormalities in serum biomarkers?