instruction:
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.
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Context: Disruptions to intermyocyte coupling have been implicated in arrhythmogenesis and development of conduction disturbances. At present, understanding of the relationship between the microscopic organization of intercellular coupling and the macroscopic spread of impulse in the normal and diseased heart is largely confined to theoretical analyses.', 'The abundance and arrangement of gap junctions, as well as conduction properties, were assessed in terminal crest preparations isolated from the atria of neonate, weanling, and adult rabbits. We report that the connexin composition of terminal crest was uncomplicated, with Cx43 being the most prominent isoform detectable by Western blotting and immunostaining. Terminal crest myocytes showed little change in total Cx43-gap junction per cell during postnatal growth as assessed by stereology. However, marked non-uniformities emerged in the sarcolemmal distribution of Cx43-gap junctions. Cx43-gap junction area at myocyte termini increased 3.5-fold from birth to adulthood. Correlated with this change in Cx43, impulse propagation velocity parallel to the myofiber axis, as assessed by multi-site optical mapping using voltage-sensitive dye (di-4-ANEPPS), increased 2.4-fold. Conversely, the amount of Cx43-gap junctions on myocyte sides, and the conduction velocity transverse to the myofiber axis, remained relatively invariant during maturation. Hence, the increasing electrical anisotropy of maturing terminal crest was wholly accounted for by increases in conductance velocity along the bundle. This increase in longitudinal conduction velocity was correlated with changes in the sarcolemmal pattern, but not the overall density, of Cx43-gap junctions.
Answer: This study provides the first correlative structure/function analysis of the relationship between the macroscopic conduction of impulse and the microscopic cellular organization of gap junctions in a differentiating cardiac bundle. Confirmation is provided for theoretical predictions which emphasize the importance of the cell-to-cell geometry of coupling in determining the spread and pattern of myocardial activation.
answer:
Are the rate and anisotropy of impulse propagation in the postnatal terminal crest correlated with remodeling of Cx43 gap junction pattern?


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Context: Noninvasive pacemaker stress echocardiography is a newly introduced method for the diagnosis of coronary artery disease in patients with a permanent pacemaker. The prognostic value of pacemaker stress echocardiography has not been studied.', 'We studied 136 patients (mean age 64+/-12 years) with a permanent pacemaker who underwent pacemaker stress echocardiography for evaluation of coronary artery disease. All patients underwent pacemaker stress echocardiography by external programming (pacing heart rate up to ischemia or target heart rate).', 'Thirty-one patients (23%) had normal study results. Ischemia was detected in 75 patients (55%). During a mean follow-up of 3.5+/-2.4 years, 35 deaths (26%) (20 the result of cardiac causes) and 2 nonfatal myocardial infarctions (1%) occurred. The annual cardiac death rate was 1.3% in patients without ischemia and 4.6% in patients with ischemia (P=.01). The annual all-cause mortality rate was 3.1% in patients without ischemia and 7% in patients with ischemia (P=.004). The presence of ischemia during pacemaker stress echocardiography was the strongest independent predictor of cardiac death (hazard ratio 4.1, confidence interval 1.2-14.5) and all-cause mortality (hazard ratio 2.7, confidence interval 1.2-6.0) in a multivariable model.
Answer: Myocardial ischemia during pacemaker stress echocardiography is an independent predictor of cardiac death and all-cause mortality in patients with a permanent pacemaker.
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Does pacemaker stress echocardiography predict cardiac events in patients with permanent pacemaker?


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Context: RECQ helicase family members act as guardians of the genome to assure proper DNA metabolism in response to genotoxic stress. Hematological malignancies are characterized by genomic instability that is possibly related to underlying defects in DNA repair of genomic stability maintenance.', 'We have investigated the expression of RECQ helicases in different hematological malignancies and in their normal counterparts using publicly available gene expression data. Furthermore, we explored whether RECQ helicases expression could be associated with tumor progression and prognosis.', 'Expression of at least one RECQ helicase family member was found significantly deregulated in all hematological malignancies investigated when compared to their normal counterparts. In addition, RECQ helicase expression was associated with a prognostic value in acute myeloid leukemia, chronic lymphocytic leukemia, lymphoma and multiple myeloma.
Answer: RECQ helicase expression is deregulated in hematological malignancies compared to their normal counterparts in association with a prognostic value. Deregulation of RECQ helicases appears to play a role in tumorigenesis and represent potent therapeutic targets for synthetic lethal approaches in hematological malignancies.
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Are rECQ helicases deregulated in hematological malignancies in association with a prognostic value?