Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In patients undergoing coronary surgery, the uptake of amino acids, which has been shown to correlate with oxygen consumption, is a mechanism of cardiac adaptation to the iatrogenic ischemia-reperfusion injury associated with cardioplegic arrest. Based on these premises, we sought to determine whether oral supplementation with mixed amino acids may protect the rat heart exposed to ischemia-reperfusion and to address whether this hypothesized cardioprotection is achieved, at least in part, through preservation of the energy-producing properties of mitochondria. Sprague-Dawley rats were fed (by enteral route) a liquid diet, with or without mixed essential amino acids (daily dose of 1 g/kg) for 30 days. Hearts from anesthetized rats were perfused by the Langendorff method and randomized to 3 groups. The control group was perfused with buffer for 60 minutes; the ischemia-reperfusion control and the amino acid-treated groups were exposed to 35 minutes of ischemia, followed by 60 or 120 minutes of reperfusion. Amino acid supplements minimized infarct size (22 +/- 1.8% vs 33 +/- 2.5%; p <0.05) and occurrence of cardiomyocyte apoptosis, as assessed by co-localization of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and caspase-3-positive staining (p <0.01). Long-term treatment with amino acids also reduced the proportion of cardiomyocytes exhibiting immunostaining for cleaved caspase-9 (p <0.01) but was ineffective on processing of caspase-8. Similar results were obtained in the whole heart by caspase activity assays (p <0.01). The lessened activation of caspase-9 detected in amino acid-treated hearts paralleled a strong reduction in mitochondrial release of cytochrome c. Adenosine triphosphate (ATP) content and rate of ATP production in isolated mitochondria were reduced by >75% in control hearts after 2 hours of reperfusion (p <0.05 vs control hearts); these values returned toward those of the control group in hearts supplemented with amino acids (p <0.01). Finally, the oxygen consumption rate in myocardial skinned bundles was markedly reduced in ischemia-reperfusion control hearts and almost normalized in amino acid-treated hearts (approximately 20% and 93% of the value for normoxic hearts; p <0.01). These results suggest that oral amino acid supplementation attenuates the extent of ischemia-reperfusion injury in the rat heart, through preservation of the mitochondria-generated production of high-energy phosphates.
 ...
PMID:Nutritional supplementation with mixed essential amino acids enhances myocyte survival, preserving mitochondrial functional capacity during ischemia-reperfusion injury. 1509 4

1. Considerable evidence indicates that calcium plays a critical role in apoptosis. We have previously shown that benidipine, a vasodilatory calcium channel blocker, attenuates postischemia myocardial apoptosis. The present study was designed to determine the mechanisms by which benidipine exerts its antiapoptotic effect. 2. Adult male rats were subjected to 30 min of ischemia followed by 3 h of reperfusion. Rats were randomized to receive either vehicle or benidipine (10 microg x kg(-1), i.v.) 10 min before reperfusion. 3. Compared with rats receiving vehicle, those rats treated with benidipine had reduced postischemic myocardial apoptosis as evidenced by decreased TUNEL-positive staining (8.4+/-1.2 vs 15.3+/-1.3%, P<0.01) and caspase-3 activity (1.94+/-0.25 vs 3.43+/-0.29, P<0.01). 4. Benidipine treatment significantly reduced mitochondrial cytochrome c release and caspase-9 activation, but had no effect on caspase-8 activation, suggesting that benidipine exerts its antiapoptotic effect by inhibiting the mitochondrial-mediated, but not death receptor-mediated, apoptotic pathway. 4. 5. Benidipine treatment not only increased the maximal activity of ERK1/2 at 10 min after reperfusion, but also prolonged the duration of ERK1/2 activation. Benidipine treatment had no significant effect on other apoptotic regulating molecules, such as p38 MAPK. 6. Taken together, our present study demonstrated for the first time the differential regulation of a calcium channel blocker. Benidipine tilted the balance between ERK1/2 and p38 MAPK toward an antiapoptotic state, decreased mitochondrial cytochrome c release, reduced caspase-9 activation, and attenuated subsequent caspase-3 activation and postischemic myocardial apoptosis.
 ...
PMID:Antiapoptotic mechanisms of benidipine in the ischemic/reperfused heart. 1517 61

Mitochondria play a critical role in the pathogenesis of cerebral ischemia. Acute hyperglycemia has been shown to activate the mitochondria-initiated cell death pathway after an intermediate period of ischemia. The objective of the present study was to determine if diabetic hyperglycemia induced by streptozotocin activates the cell death pathway after a brief period of global ischemia. Five minutes of global ischemia was induced in nondiabetic and diabetic rats. Brain samples were collected after 30 min, 6 h, 1, 3, and 7 days of recirculation as well as from sham-operated controls. Histopathological examination in the hippocampal CA1, CA3, hilus, and dentate gyrus regions, as well as in the cortical and thalamic areas, showed that neuronal death in diabetic animals increased compared to nondiabetic ischemic controls. Neuronal damage maturation occurred after 7 days of recovery in nondiabetic rats, while it was shortened to 3 days of recovery in diabetic animals. Western blot analyses revealed that release of cytochrome c markedly increased after 1 and 3 days of reperfusion in diabetic rats. Caspase-3 activation was evident in the nuclear fraction of the cortex of diabetic rats after 3 days recovery and it was preceded by activation of caspase-9, but not activation of caspase-8. Electron microscopy demonstrated that chromatin condensation and mitochondrial swelling were features of the diabetes-mediated ischemic neuronal damage. However, no apoptotic bodies were observed in any sections examined. These results suggest that a brief period of global ischemia in diabetic animals activates a neuronal cell death pathway involving cytochrome c release, caspase-9 activation, and caspase-3 cleavage, all of which are most likely initiated by early mitochondria damage.
 ...
PMID:Activation of cell death pathway after a brief period of global ischemia in diabetic and non-diabetic animals. 1524 41

Cardiomyocyte apoptosis contributes to cell death during myocardial infarction. One of the factors that regulate the degree of apoptosis during ischemia is the amino acid taurine. To study the mechanism underlying the beneficial effect of taurine, we examined the interaction between taurine and mitochondria-mediated apoptosis using a simulated ischemia model with cultured rat neonatal cardiomyocytes sealed in closed flasks. Exposure to medium containing 20 mM taurine reduced the degree of apoptosis following periods of ischemia varying from 24 to 72 h. In the untreated group, simulated ischemia for 24 h led to mitochondrial depolarization accompanied by cytochrome c release. The apoptotic cascade was also activated, as evidenced by the activation of caspase-9 and -3. Taurine treatment had no effect on mitochondrial membrane potential and cytochrome c release; however, it inhibited ischemia-induced cleavage of caspase-9 and -3. Taurine loading also suppressed the formation of the Apaf-1/caspase-9 apoptosome and the interaction of caspase-9 with Apaf-1. These findings demonstrate that taurine effectively prevents myocardial ischemia-induced apoptosis by inhibiting the assembly of the Apaf-1/caspase-9 apoptosome.
 ...
PMID:Taurine inhibits apoptosis by preventing formation of the Apaf-1/caspase-9 apoptosome. 1525 91

We describe the isolation and characterization of a new apaf-1-interacting protein (APIP) as a negative regulator of ischemic injury. APIP is highly expressed in skeletal muscle and heart and binds to the CARD of Apaf-1 in competition with caspase-9. Exogenous APIP inhibits cytochrome c-induced activation of caspase-3 and caspase-9, and suppresses cell death triggered by mitochondrial apoptotic stimuli through inhibiting the downstream activity of cytochrome c released from mitochondria. Conversely, reduction of APIP expression potentiates mitochondrial apoptosis. APIP expression is highly induced in mouse muscle affected by ischemia produced by interruption of the artery in the hindlimb and in C2C12 myotubes created by hypoxia in vitro, and the blockade of APIP up-regulation results in TUNEL-positive ischemic damage. Furthermore, forced expression of APIP suppresses ischemia/hypoxia-induced death of skeletal muscle cells. Taken together, these results suggest that APIP functions to inhibit muscle ischemic damage by binding to Apaf-1 in the Apaf-1/caspase-9 apoptosis pathway.
 ...
PMID:Induced inhibition of ischemic/hypoxic injury by APIP, a novel Apaf-1-interacting protein. 1526 85

After cardiac transplantation, graft damage occurs secondary to ischemia-reperfusion injury and acute rejection. This damage ultimately leads to the development of graft coronary artery disease (GCAD), which limits long-term graft survival. Apoptosis is directly involved in graft injury, contributing to the development of GCAD. To assess the role of the antiapoptotic factor Bcl-2 in the process of GCAD, we transplanted hearts from FVB transgenic mice overexpressing human Bcl-2 under the control of alpha-myosin heavy chain promoter into allogenic C57BL/6 mice. Bcl-2 overexpression led to reduced cytochrome c-mediated caspase-9-dependent cardiomyocyte apoptosis and local inflammation (neutrophil infiltration and proinflammatory cytokine production) in cardiac allografts during ischemia-reperfusion injury and also led to reduced immune responses (inflammatory cell infiltration, production of T(H)1 cytokines and chemokines, and expression of adhesion molecules) during acute and chronic rejection without affecting host CD4(+) and CD8(+) cell responses in the spleen. Thus, local Bcl-2 expression directly contributes to the modulation of local immune responses in allograft rejection, resulting in attenuated GCAD. In conclusion, our findings suggest that the modulation of Bcl-2 expression by pharmacologic up-regulation or gene transfer may be of clinical benefit in the short- and long-term function of cardiac allografts.
 ...
PMID:Cardiomyocyte-specific Bcl-2 overexpression attenuates ischemia-reperfusion injury, immune response during acute rejection, and graft coronary artery disease. 1528 Feb 1

To investigate the in vivo apoptotic machinery in oxygen deprived brain, we examined the expression of caspase-9 and caspase-3 in the hippocampus of Mongolian gerbils subjected to either transient hypoxia (4% O2 for 6 min) or forebrain ischemia (10 min bilateral carotid artery occlusion) followed by 8 h to 7 days of reoxygenation or blood recirculation. Apoptotic death was characterized by isolating hippocampal genomic DNA and analysing DNA fragmentation as well as histological studies including TUNEL assay and toluidine blue staining of brain sections. The results showed that both hypoxic and ischemic gerbil brains exhibited an increase in caspase-9 and caspase-3 gene expression. However, no cell damage was detectable following hypoxia, while marked DNA fragmentation and extensive cell death was observed following ischemia. Moreover, although hypoxia did not lead to cell death, both hypoxia and ischemia were associated with cleavage of procaspase-9 and procaspase-3 and increases in their activities as well as cleavage of poly(ADP-ribose) polymerase-1 (PARP-1), a major caspase-3 substrate. These results indicate that, in vivo, even late apoptotic events such as caspase activation and PARP-1 cleavage in hypoxic brains do not necessarily induce an irreversible commitment to apoptotic neuronal death.
 ...
PMID:Hypoxia induces caspase-9 and caspase-3 activation without neuronal death in gerbil brains. 1530 62

In hypoxia, ATP depletion causes cellular Ca(2+) increase, mitochondrial injury, and apoptosis in renal tubular cells. However, the molecular basis of these observations is incompletely delineated. IRPTC, a rat renal proximal tubular cell line, was treated with antimycin A, and disturbances in cytoplasmic calcium ([Ca(2+)]c) and mitochondrial calcium ion concentration ([Ca(2+)]m), dissipation of mitochondrial membrane potential (DeltaPsi(m)), cytochrome c release, and resultant apoptosis were examined. Pharmacologic targeting of L-type Ca(2+) channels in vitro and in vivo was used to clarify the involvement of voltage-dependent Ca(2+) channels during this process. In vitro studies indicated that ATP depletion-induced apoptosis was preceded by increased [Ca(2+)]c and [Ca(2+)]m before activation of mitochondrial signaling. Antagonizing L-type Ca(2+) channels offset these findings, suggesting [Ca(2+)]c and [Ca(2+)]m involvement. Azelnidipine administration ameliorated cellular and mitochondrial Ca(2+) accumulation, mitochondrial permeability transition, cytochrome c release, caspase-9 activation, and resultant apoptosis (15.8 +/- 0.8% versus 8.9 +/- 0.7%; P < 0.01). Similar effects of azelnidipine were substantiated in an in vivo ischemia/reperfusion injury model. There were fewer terminal-deoxynucleotidyl transferase mediated dUTP nick-end labeling-positive cells in the azelnidipine-treated group (0.322 +/- 0.038/tubule) as compared with the vehicle-treated group (0.450 +/- 0.041; P < 0.05), although the antiapoptotic effect was smaller in vivo than in vitro, partly as a result of distinct levels of Bax expression. It is proposed that voltage-dependent Ca(2+) channels are involved in cellular and mitochondrial accumulation of Ca(2+) subsequent to ATP depletion and play an important role in regulating mitochondrial permeability transition, cytochrome c release, caspase activation, and apoptosis.
 ...
PMID:Blockade of calcium influx through L-type calcium channels attenuates mitochondrial injury and apoptosis in hypoxic renal tubular cells. 1533 81

Apoptosis is a form of cell death which utilizes energy resources to dismantle and remove cells in an orderly or programmed fashion. It plays an essential role in establishing normal embryonic development, maintaining adult tissue homeostasis and contributes to a variety of human diseases including certain pathological processes in the heart. Apoptosis is mediated by a distinct biochemical pathway that is conserved in multicellular organisms. Signaling for apoptosis is initiated from outside the cell (extrinsic or death receptor pathway) or from inside the cell (intrinsic or mitochondrial pathway). In both pathways, signaling results in the activation of a family of cysteine proteases, named caspases, that act in a proteolytic cascade to dismantle and remove the dying cell. The activation of the intrinsic death pathway involves the release of cytochrome c from the mitochondria and formation of the apoptosome, a catalytic multiprotein platform that activates caspase-9. There is evidence that the mitochondrial pathway is involved in ischemia-induced myocyte apoptosis in the heart. Diminished expression of pro-apoptotic factors and/or expression of certain inhibitors of the apoptosome may raise the threshold for apoptosis in long-lived post-mitotic cells including myocytes of the heart.
 ...
PMID:Apoptosome formation and caspase activation: is it different in the heart? 1535 Aug 37

The pattern of cell death in the immature brain differs from that seen in the adult CNS. During normal development, more than half of the neurons are removed through apoptosis, and mediators like caspase-3 are highly upregulated. The contribution of apoptotic mechanisms in cell death appears also to be substantial in the developing brain, with a marked activation of downstream caspases and signs of DNA fragmentation. Mitochondria are important regulators of cell death through their role in energy metabolism and calcium homeostasis, and their ability to release apoptogenic proteins and to produce reactive oxygen species. We find that secondary brain injury is preceded by impairment of mitochondrial respiration, signs of membrane permeability transition, intramitochondrial accumulation of calcium, changes in the Bcl-2 family proteins, release of proapoptotic proteins (cytochrome C, apoptosis inducing factor) and downstream activation of caspase-9 and caspase-3 after hypoxia-ischemia. These data support the involvement of mitochondria-related mechanisms in perinatal brain injury.
 ...
PMID:Mitochondrial impairment in the developing brain after hypoxia-ischemia. 1537 74


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>