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)

Ceramide is a key mediator of apoptosis during the cellular stress response which is also involved in stroke-induced death. Transient occlusion of the middle cerebral artery (MCA) in rats led to a strong generation of ceramide as measured in thalamus and entorhinal cortex of the ischemic brain tissue. Enhanced levels of ceramide may be involved in apoptosis signaling following stroke since exogenously added synthetic C2-ceramide increased expression of c-jun and the death-inducing ligands (DILs) CD95-L, TRAIL and TNF-alpha in neuroblastoma cells. DILs in turn mediated death via binding to their respective receptors as concluded from diminished apoptosis upon blocking of the common pathway by dominant negative FADD. C2-ceramide induced both necrosis and apoptosis in a concentration-dependent manner corresponding to the situation present in the ischemic brain. The immunosuppressant FK506 inhibited the release of ceramide, expression of CD95-L and apoptosis in an in vitro and in vivo model for ischemia/reperfusion. These data suggest that ceramide is a crucial initiator of death, e.g., by induction of DILs following stroke.
 ...
PMID:FK506 prevents stroke-induced generation of ceramide and apoptosis signaling. 1022 98

Recent evidence has implicated proinflammatory mediators such as TNF- alpha in the pathophysiology of ischemia-reperfusion (I/R) injury. Clinically, serum levels of TNF-alpha are increased after myocardial infarction and after cardiopulmonary bypass. Each of these represent clinically relevant instances of cardiac I/R injury. We and others have recently reported that TNF-alpha is produced by the heart following experimental I/R in animals and that TNF-alpha directly decreases animal and human myocardial contractility in a dose dependent fashion. Thus, strategies to reduce or neutralize myocardial TNF- alpha production should conceptually decrease myocardial contractile dysfunction following I/R. The purposes of this manuscript are: 1) to explore the clinical and experimental instances of I/R injury in which TNF-alpha is elevated, 2) to review the molecular mechanisms of TNF- alpha induced contractile dysfunction, 3) to examine both experimental and clinical strategies of reducing myocardial TNF-alpha production, and 4) to determine the influence of reducing post-I/R TNF-alpha on cardiac contractile function in both animals and man.
 ...
PMID:Therapeutic strategies to reduce TNF-alpha mediated cardiac contractile depression following ischemia and reperfusion. 1033 35

In traumatized and septic patients, excessive cytokine production may lead to organ dysfunction and death. Current understanding of cytokine kinetics with regard to clinical scenarios, however, is still limited by a paucity of studies investigating the cytokine levels in humans with inflammation-reperfusion injury in the absence of infection. Our hypothesis was that endotoxin is introduced into circulation during and after abdominal aortic aneurysm (AAA) repair and is associated with pro- and anti-inflammatory cytokine-response. The purpose of this prospective pilot study in 10 patients who underwent elective AAA repair was to assess organ function and immune response to systemic endotoxemia after the operation by measuring endotoxin, endotoxin neutralizing capacity (ENC), tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-10, and TNF-RI and II. Blood samples were obtained from indwelling catheters or direct venipuncture preoperatively, perioperatively (8 time points) until the second postoperative day. Endotoxin and ENC were determined by a special kinetic Limulus amoebocyte lysate (LAL) assay and TNF-alpha, IL-6, IL-10, and TNF-RI and II by commercial ELISA. Endotoxin levels were significantly elevated after declamping and 90 min after clamping of the aorta (2.3 + .9 pg/mL; 5.4+/-3.6 pg/mL). ENC decreased to the lowest levels at 90 min after clamping. TNF-alpha levels were maximal, but not significantly elevated, 120 min after clamping. IL-6 increased significantly during the operation and reached maximum levels (189.8+/-47 pg/mL) at the first postoperative day. Anti-inflammatory IL-10 and TNF-RI and II were elevated early during the operation. The changes in cytokine levels were associated with mild organ dysfunction. We conclude that AAA repair is associated with endotoxin, proinflammatory, and an almost coincidental anti-inflammatory cytokine release, providing baseline data about what constitutes an appropriate immune response. Such responses to trauma and ischemia-reperfusion need to be further investigated before attempting immunomodulation.
 ...
PMID:Pro- and anti-inflammatory cytokine-response in abdominal aortic aneurysm repair: a clinical model of ischemia-reperfusion. 1035 34

Using a polyclonal antibody against rat TNF-alpha, we have identified specific intracellular immunoreactive sites in hippocampal pyramidal cells, astroglia, and in microglia within 72 h after a period of ischemia. Electron opaque immunoreactive products in pyramidal cells were found mainly in somata and dendrites. Astrocytes and microglia were nearly devoid of such complexes. These findings demonstrate the presence of TNF-alpha in hippocampal neurons and its enhancement by ischemic stress.
 ...
PMID:Ultrastructural localization of hippocampal TNF-alpha immunoreactive cells in rats following transient global ischemia. 1037 86

With the use of immunohistochemical technique, nerve biopsy is more informative for the diagnosis of inflammatory neuropathies. In chronic inflammatory demyelinating neuropathy, an increased number of T cells are frequently present in endoneurium, which is in contrast to hereditary neuropathies. In active demyelinating lesions, macrophages adhering nerve fibers showed stainings with TNF-alpha. NOS and cyclooxygenase-2 (COX-2). These molecules may act in concert to promote nerve damage. The inhibitor of COX-2, nimesulide, was effective on experimental allergic neuritis, even if given after the onset of clinical signs. A COX-2 inhibitor may have potential as an additional therapeutic agent in human inflammatory neuropathies. In vasculitic neuropathies, cell-mediated cytotoxicity may be involved in the pathogenesis of small vessel injury. Axonal injury may be caused by focal ischemia. However, an immune attack might be involved in nerve damage, since T cells and IL-12 positive cells were found in endoneurium of some patients with active vasculitis.
 ...
PMID:[Immunopathology of inflammatory neuropathies]. 1037 18

The liver is an organ with abundant blood flow, consisting of hepatic arterial and portal blood flow. The viability of liver tissue depends on the condition of the hepatic microcirculation which is controlled by hepatic sinusoidal lining cells. Hepatic ischemia and reperfusion (HIR) injury is inevitable in surgical procedures for liver trauma and hepatectomy as well as liver transplantation. Reperfusion through an ischemically damaged organ enhances the tissue injury. Cytokines are pivotal factors in neutrophil-mediated liver injury following HIR, while various other mediators are involved in this insult. Advances in molecular biology have allowed the identification of various cytokines. Inflammatory cytokines such as TNF-alpha are associated with the induction of cellular adhesion molecules and hepatic microcirculatory impairment based on neutrophil-vascular endothelial cell interaction. Members of the chemokine family such as IL-8, CINC, MIP-2, and MCP-1 are involved in neutrophil infiltration in the liver and remote organs. Since each cytokine has a wide variety of actions and interacts' among others' via the cytokine network, their actions in HIR injury have not been determined completely. Kupffer cells have been focused on as a source of cytokine production in HIR injury. Further studies on the mechanisms of cytokine production after HIR and analysis of regulation in the cytokine network would clarify the pathophysiology of HIR injury and the most suitable therapeutic strategy for this insult.
 ...
PMID:[Role of cytokines in hepatic ischemia and reperfusion injury]. 1041 51

Recent evidence has implicated proinflammatory mediators such as TNF-alpha in the pathophysiology of ischemia-reperfusion (I/R) injury. Clinically, serum levels of TNF-alpha are increased after myocardial infarction and after cardiopulmonary bypass. Both cardiopulmonary bypass and renal ischemia-reperfusion injury induce a cascade of events leading to cellular damage and organ dysfunction. Tumor necrosis factor (TNF), a potent proinflammatory cytokine, is released from both the heart and the kidney in response to ischemia and reperfusion. TNF released during cardiopulmonary bypass induces glomerular fibrin deposition, cellular infiltration, and vasoconstriction, leading to a reduction in glomerular filtration rate (GFR). The signaling cascade through which renal ischemia-reperfusion induces TNF production is beginning to be elucidated. Oxidants released following reperfusion activate p38 mitogen-activated protein kinase (p38 MAP kinase) and the TNF transcription factor, NFkappaB, leading to subsequent TNF synthesis. In a positive feedback, proinflammatory fashion, binding of TNF to specific TNF membrane receptors can reactivate NFkappaB. This provides a mechanism by which TNF can upregulate its own expression as well as facilitate the expression of other genes pivotal to the inflammatory response. Following its production and release, TNF results in both renal and myocardial apoptosis and dysfunction. An understanding of these mechanisms may allow the adjuvant use of anti-TNF therapeutic strategies in the treatment of renal injury. The purposes of this review are: (1) to evaluate the evidence which indicates that TNF is produced by the heart following cardiopulmonary bypass; (2) to examine the effect of TNF on myocardial performance; (3) to outline the mechanisms by which the kidney produces significant TNF in response to ischemia and reperfusion; (5) to investigate the role of TNF in renal ischemia-reperfusion injury, (6) to describe the mechanisms of TNF-induced renal cell apoptosis, and (7) to suggest potential anti-TNF strategies designed to reduce renal insufficiency following cardiac surgery.
 ...
PMID:Role of TNF in mediating renal insufficiency following cardiac surgery: evidence of a postbypass cardiorenal syndrome. 1042 18

There is a large body of evidence that the liver microcirculation has to be considered as a major target in hepatic ischemia/reperfusion injury. The nature of microvascular injury, which precedes manifestation of hepatic parenchymal tissue damage, includes both hypoxia due to lack of microvascular perfusion (i.e. no-reflow), and a reperfusion-associated inflammatory response, which includes the activation and dysfunction of leukocytes and Kupffer cells (the reflow paradox). No-reflow in sinusoids is thought to be caused by endothelial cell swelling and intravascular hemoconcentration, and involves also a deterioration of the balance between ET and NO. The reflow paradox is associated with: (i) the release and action of proinflammatory cytokines (TNF-alpha, IL-1) and oxygen radicals; (ii) the up-regulation of endothelial and leukocytic adhesion molecules (selectins, beta-integrins, ICAM-1); and (iii) the interaction of leukocytes with the endothelial lining of the hepatic microvasculature.
 ...
PMID:Role of microcirculation in hepatic ischemia/reperfusion injury. 1043 6

Proinflammatory cytokines are produced in the brain after various kinds of insult (ischemia, trauma, infection). In this process interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF)-alpha are most important. These cytokines are key mediators of inflammation. Furthermore, these cytokines can act as neurotransmitters and develop direct effects on the central nervous system (CNS) including fever, sleep and stimulation of the neuroendocrine as well as sympathetic nervous system. Moreover, IL-1beta and TNF-alpha may also be involved in brain repair and regenerating processes. However, most of the data about the role of cytokines in the brain have been obtained from either in vitro studies or bolus injections into the brain parenchyma or cerebroventricular system. On the other hand, it is known that cytokines are released continuously into the brain after a cerebral insult over a period of 24 to 48 h. In order to further complete the knowledge about the interactions between neural and immune cells to overcome the primary insult and initiate repair and regeneration in the CNS, a new animal model of local inflammation reaction was established using chronic intracerebral infusion of rat recombinant cytokines.
 ...
PMID:Continuous infusion of proinflammatory cytokines into the brain to study brain cytokine induced local and systemic immune effects. 1044 17

Accelerated hepatic apoptosis was first described in portal vein-ligated livers but has since been reported in a variety of liver injuries. Because porto-prival states can induce apoptosis we sought to determine whether transient ischemic periods followed by reperfusion would trigger such cell death. The cytokines TNF-alpha and TGF-beta are known to facilitate apoptosis and are released in response to a number of stimuli including ischemia. We also investigated alterations in plasma and tissue levels of these cytokines which might lend support to their role in increased apoptotic activity following ischemia/reperfusion. Female pigs were used as the experimental model. Inflow occlusion of portal and hepatic arterial blood was performed to a portion of the swine liver directing the entire splanchnic flow to the remaining hepatic lobes for a period of 2 h. The livers were then reperfused and plasma and tissue samples taken for determination of apoptotic activity utilizing cell death immunoperoxidase staining of 3'-OH DNA ends generated by fragmentation and ELISA assay of histone-associated DNA fragments. Plasma and tissue levels of TNF-alpha and plasma levels of TGF-beta were determined by ELISA assay. An increase in apoptotic activity following reperfusion was seen at Day 2 and Day 4 compared to preischemic values by the cell death stain. The ELISA cell death assay showed an increase in apoptotic activity at 60 min, Day 2, and Day 4. Moreover, the ELISA cell death assay showed enhanced apoptotic activity in "hyperperfused" hepatic lobes compared to preischemic, or resting, liver. This was also observed when compared to sham-operated animals. Surprisingly, there was no detectable increase in plasma TNF-alpha or TGF-beta levels following ischemia/reperfusion, although homogenized liver TNF-alpha levels were increased at 60 min and Day 2 following reperfusion. We conclude that transient hepatic inflow occlusion followed by reperfusion can induce increased apoptotic activity in the swine model. Furthermore, increased apoptotic activity also occurs in the hyperperfused liver raising the possibility of a locally active factor or global hepatic expression of receptor activity in response to ischemia/reperfusion. This period of ischemia/reperfusion did not produce a detectable increase in circulating cytokine levels, and accelerated apoptosis could not be linked to heightened TNF-alpha or TGF-beta plasma activity. Higher tissue levels of TNF-alpha could reflect enhanced binding to TNF cell surface receptors or amplified receptor expression.
 ...
PMID:Hepatic apoptotic activity following transient normothermic inflow occlusion and reperfusion in the swine model. 1045 71


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