Citations

Abstract —Communication between the cytoplasm and nucleoplasm of cardiac cells occurs by molecular transport through nuclear pores. In lower eukaryotes, nuclear transport requires the maintenance of cellular energetics and ion homeostasis. Although heart muscle is particularly sensitive to metabolic stress, the regulation of nuclear transport through nuclear pores in cardiomyocytes has not yet been characterized. With the use of laser confocal and atomic force microscopy, we observed nuclear transport in cardiomyocytes and the structure of individual nuclear pores under different cellular conditions. In response to the depletion of Ca 2+ stores or ATP/GTP pools, the cardiac nuclear pore complex adopted 2 distinct conformations that led to different patterns of nuclear import regulation. Depletion of Ca 2+ indiscriminately prevented the nuclear import of macromolecules through closure of the nuclear pore opening. Depletion of ATP/GTP only blocked facilitated transport through a simultaneous closure of the pore and relaxation of the entire complex, which allowed other molecules to pass into the nucleus through peripheral routes. The current study of the structural plasticity of the cardiac nuclear pore complex, which was observed in response to changes in cellular conditions, identifies a gating mechanism for molecular translocation across the nuclear envelope of cardiac cells. The cardiac nuclear pore complex serves as a conduit that differentially regulates nuclear transport of macromolecules and provides a mechanism for the control of nucleocytoplasmic communication in cardiac cells, in particular under stress conditions associated with disturbances in cellular bioenergetics and Ca 2+ homeostasis.

Abstract The presence of ≥ 15% bone marrow (BM) ring sideroblasts (RS) and < 5% blasts is required for a diagnosis of refractory anemia with ring sideroblasts. We examined the phenotypic and prognostic relevance of this “15%” RS threshold in 200 patients with myelodysplastic syndromes (MDS) without excess blasts and with ≥ 1% RS. The impact of RS% was assessed both as a continuous and categorical variable: < 5% (n = 56), 5%-14% (n = 32), 15%-50% (n = 79), and > 50% (n = 33). RS% correlated (P < .05) directly with age, platelet count, transfusion dependency, BM cellularity, and mutant SF3B1 and inversely with hemoglobin level, multilineage dysplasia, and high-risk karyotype; but did not correlate with IDH mutations. At a median follow-up of 33 months, 156 (73%) deaths and 24 (12%) leukemic transformations were documented. Neither univariate nor multivariable analysis showed significant effect for RS% on overall or leukemia-free survival, suggesting the limited prognostic value of quantifying BM RS in MDS.

Aims: Percutaneous coronary intervention (PCI) is frequently accompanied by myocardial injury. The present study was performed to determine whether remote ischemic preconditioning (IP) induces cardioprotection during PCI. Methods: We enrolled 95 patients requiring nonemergency PCI for stable disease or unstable angina into this prospective clinical trial. Patients were randomized to either remote IP (induced by three 3‐min cycles of blood pressure cuff inflations to 200 mm Hg around the upper arm, followed by 3‐min of reperfusion n = 47) or sham control ( n = 48) immediately preceding PCI. The primary outcome measure was the frequency of post‐PCI myonecrosis, defined as a peak postprocedural cTnT T ≥0.03 ng/dL. Secondary outcome measures were the change in plasma high‐sensitivity C‐reactive protein (hsCRP) levels following PCI and in endothelial progenitor cells (EPC) counts following IP. Results: There was no difference in the primary endpoint of the frequency of PCI related myonecrosis which occurred in 22 (47%) and 19 (40%) patients in the remote IP and control groups, respectively, P = 0.42. There was significant increase in hsCRP post‐PCI in both groups ( P < 0.001), but there was no difference between the groups (median %change in hsCRP 46% vs. 54%, P = 0.73). There was no significant change in circulating early (CD34 −/CD133+/KDR+), intermediate (CD34+/CD133+/KDR+), or late (CD34+/CD133−/KDR+) EPC in the two groups immediately following IP. The composite rate of death, myocardial infarction, and target lesion revascularization at 1 year was 14.1% versus 13.7% ( P = 0.90). Conclusions: Our study indicates that remote IP immediately before PCI does not induce cardioprotection in low to moderate risk patients. © 2012 Wiley Periodicals, Inc.