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.
question:
Context: Progenitor cells isolated from cardiac explant-derived cells improve cardiac function after myocardial infarction (MI). To fully realize the therapeutic potential of these cells, it is essential to develop a safe and efficient delivery method. Therefore, the objective of this study was to determine the efficacy of our newly developed approach to retrograde coronary vein (RCV) infusion of cardiac c-Kit(+) cells in a small-animal model of congestive heart failure (CHF).', 'Sprague-Dawley rats underwent experimental MI. After 21 days, cardiac explant-derived c-Kit(+) cells were delivered to both sham and CHF animals using RCV delivery. Vehicle-treated (serum-free medium) sham and CHF animals were used as controls. Cardiac function and heart tissues were evaluated 21 days post-transplantation.', 'RCV-delivered cells were retained in infarcted hearts for at least 21 days after transplantation. At 21 days post-RCV infusion, the majority of transplanted c-Kit(+)/GFP(+) cells were localized in the left ventricle. Compared with vehicle-treated CHF animals, RCV-treated rats showed a significant improvement in cardiac function. Furthermore, RCV-treated rats exhibited an increase in capillary density, a decrease in total heart collagen, and a reduction in both infarct size and cardiomyocyte hypertrophy when compared with vehicle-treated CHF rats.
Answer: Our study showed that the RCV infusion approach is an efficient technique for targeted cell delivery to the infarcted myocardium. Cardiac c-Kit(+) cells, delivered using RCV infusion ameliorated progression of heart failure, improved cardiac function and retarded myocardial remodeling in heart failure rats.
answer:
Does retrograde coronary vein infusion of cardiac explant-derived c-Kit+ cells improves function in ischemic heart failure?


question:
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: Restenosis occurs in 40-50% of patients treated with percutaneous transluminal coronary angioplasty (PTCA). Some data indicate that platelet derived growth factor (PDGF) plays a pathogenetic role. The aims of the present study were to measure the plasma levels of PDGF across the coronary circulation during PTCA and relate them to the development of restenosis.', 'Blood samples from the aortic root and coronary sinus were drawn simultaneously before, and after completed PTCA in 26 patients. Plasma levels of PDGF and beta-thromboglobulin (BTG), as well as platelet counts were measured. Restenosis was evaluated by quantitative coronary angiography after 6 months. Significant increases both in PDGF and BTG were encountered in the aortic root after PTCA in patients who developed restenosis as compared to patients without restenosis. Patients who developed restenosis also had significantly higher platelet counts compared to those without.
Answer: Increases in plasma PDGF and BTG in the aortic root after PTCA seem to be markers for restenosis 6 months after PTCA. This finding may strengthen the hypothesis that platelets contribute to the process of restenosis.
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Are blood platelet count and reactivity associated with restenosis 6 months after coronary angioplasty?