Nitrite (NO2
−) is an intrinsic signaling molecule that is reduced to NO during ischemia and limits apoptosis and cytotoxicity at reperfusion in the mammalian heart, liver, and brain. Although the mechanism of nitrite-mediated cytoprotection is unknown, NO is a mediator of the ischemic preconditioning cell-survival program. Analogous to the temporally distinct acute and delayed ischemic preconditioning cytoprotective phenotypes, we report that both acute and delayed (24 h before ischemia) exposure to physiological concentrations of nitrite, given both systemically or orally, potently limits cardiac and hepatic reperfusion injury. This cytoprotection is associated with increases in mitochondrial oxidative phosphorylation. Remarkably, isolated mitochondria subjected to 30 min of anoxia followed by reoxygenation were directly protected by nitrite administered both in vitro during anoxia or in vivo 24 h before mitochondrial isolation. Mechanistically, nitrite dose-dependently modifies and inhibits complex I by posttranslational S-nitrosation; this dampens electron transfer and effectively reduces reperfusion reactive oxygen species generation and ameliorates oxidative inactivation of complexes II–IV and aconitase, thus preventing mitochondrial permeability transition pore opening and cytochrome c release. These data suggest that nitrite dynamically modulates mitochondrial resilience to reperfusion injury and may represent an effector of the cell-survival program of ischemic preconditioning and the Mediterranean diet.
SUMMARYPrimary leiomyosarcomas of the heart, particularly those affecting the right ventricle, are uncommon. We report the case of a 70-year-old Belgian woman presenting with the symptoms of progressive exertional dyspnea and left-sided pleuritic pain. A leiomyosarcoma which originated from the right lateral ventricle wall, causing pulmonary outflow obstruction. was diagnosed. Pathology revealed a neoplasm with a myxoid stroma, high mitotic activity and nuclei expressing atypia. Immunohistochemical staining was positive for vimentine and desmin. Seven months after complete surgical resection the tumor relapsed.This case demonstrates the poor outcome, the high relapse rate and inefficiency of treatment associated with primary cardiac leiomyosarcomas. The current literature regarding the incidence, diagnostic techniques, treatment strategies and survival rates of this rare but terminal disease is reviewed. (Jpn Heart J 2001; 42: 377-386)
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