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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxygen free radicals (OFR) are thought to mediate ischemia-reperfusion injury to endothelium of heart, lung, brain, liver, and kidney and contribute to development of atherosclerosis, pulmonary O2 toxicity, and adult respiratory distress syndrome. Increased cytosolic free Ca2+ (Cai2+) has been proposed as a mechanism of injury from oxidative stress, yet the pathways by which an increase in Cai2+ may cause OFR-mediated endothelial cell injury remain unknown. Using multiparameter digitized video microscopy and the fluorescent probes, fura-2 acetoxymethyl ester and propidium iodide, we measured Cai2+ and cell viability in human umbilical endothelial cells during oxidative stress with xanthine (50 microM) plus xanthine oxidase (40 mU/ml). Oxidative stress caused a sustained increase in Cai2+ from a resting level of 90-100 nM to near 500 nM, which was preceded by formation of plasma membrane blebs. The increase in Cai2+ was prevented by removal of extracellular Ca2+ (Cao2+). Prevention of the increase in Cai2+ was associated with prolonged cell viability. Readdition of Cao2+ resulted in an immediate large increase in Cai2+ and rapid onset of cell death. The protease inhibitors, leupeptin and pepstatin, delayed the increase in Cai2+ and prolonged cell viability. The results are consistent with the hypothesis that endothelial cell injury due to oxidative stress may be the result of Cai2+ influx and resultant activation of Ca(2+)-dependent proteases.
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PMID:Cytosolic free Ca2+ and proteolysis in lethal oxidative injury in endothelial cells. 195 73

The hypothesis that a significant reduction in colonic mucosal perfusion, and hence ischemic injury, precedes the development of mucosal ulceration and inflammation is tested in this report. The microcirculatory changes in the rat colonic mucosa within 1 hr of topical exposure to 10% acetic acid were assessed. Colonic mucosal blood flow signals measured by laser Doppler flowmetry were significantly reduced to 61 +/- 8, 52 +/- 10, and 37 +/- 13% (mean +/- SEM) of baseline values at 1 min, 4 min, and 10 min after the colonic mucosa was exposed to 10% acetic acid, respectively, but not in controls exposed to saline. After the start of application of 10% acetic acid (for 4 min), in vivo microscopy studies demonstrated that colonic mucosal ischemia (stasis of the red blood cells in the mucosal capillaries) occurred at 9 +/- 5 min (mean +/- SEM). Evidence of endothelial cell death (failure to exclude a fluorescent dye, propidium iodide, by endothelial cells) developed at 25 +/- 10 min (mean +/- SEM). These findings indicate that within minutes after contact of the colonic mucosa with 10% acetic acid, colonic mucosal ischemia develops, followed shortly by death of endothelial cells. The data do not establish a cause-and-effect relationship between the reductions in mucosal blood flow and loss of endothelial cell viability in response to acetic acid. Nevertheless, because these events occur at such an early time point, they may play a pathogenetic role in the development of the subsequent inflammatory and ulcerative changes in this animal model of colitis. Further studies to define the potential causal relationships between these parameters are warranted.
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PMID:Mucosal vascular stasis precedes loss of viability of endothelial cells in rat acetic acid colitis. 203 12

Starting from the assumption that tumor cells constantly experience transient ischemia and anoxia, and that this results in metabolic stress which is reflected above all, on the concentration of ATP, ADP and AMP, in other words, the adenine nucleotide pool (AdN), the aim of our research was to study the degradation and resynthesis kinetics of that pool on two types of malignant cells. All experiments were conducted in vitro with cells of the transplantable tumors of Ehrlich's ascitic carcinoma and the AS 30D hepatoma, and metabolite analyses were carried out enzymatically or by way of the HPLC chromatography method. It was found that immediately after the setting on of anoxia, there comes not only to a fall in ATP, but also to a fall in the complete adenine nucleotide pool for about 50%. The further maintenance of anaerobiosis does not have a significant influence on the AdN pool. The adenine nucleotide pool resynthesis is very rapid in the examined cells, and in the presence of glutamine and inosine, there comes to an occurrence of its significant growth. Evidence is given that the resynthesis in Ehrlich's ascitic carcinoma cells is made possible through the purine nucleotide cycle, which probably brings about the intensive glutamine oxidation and aspartate production, while in the AS 30D hepatoma cells it develops by means of adenosine kinase. The AS 30D hepatoma cells maintain a high ATP level in the absence of oxygen for a long time, provided that iodine-acetate is not added, which points to the fact that they have some other kind of energetic reserve aside from ATP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Kinetics of degradation and resynthesis of the adenine-nucleotide pool in tumor cells]. 209 81

The susceptibility of lung tissue to ischemia-reperfusion injury has made distant procurement of heart-lung allografts difficult. The effects of hypothermia, ventilation without perfusion, and various reperfusion solutions (PSS/Ficoll or whole blood) on the development of ischemia-reperfusion lung injury were investigated. Use of an ex vivo rat lung model in which the above variables were individually varied permitted a direct approach for these studies. Normothermic ischemia for 1 hour caused significant damage, documented by increased iodine 125 bovine serum albumin (125I-BSA) in alveolar lavage fluid and lung parenchyma compared with nonischemic controls. Hypothermic (4 degrees C) ischemia for 4 hours in lungs reperfused with salt solution and for as many as 12 hours in lungs reperfused with whole blood caused no significant increase in 125I-BSA in alveolar lavage fluid and lung parenchyma compared with nonischemic controls. Lungs ventilated without perfusion showed no increase in 125I-BSA leakage compared with controls. The ex vivo rat lung model is excellent for studying ischemia-reperfusion injury. It is reproducible, allows for variance of reperfusion solutions, and permits change in temperature and ventilation easily.
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PMID:Hypothermia or continuous ventilation decreases ischemia-reperfusion injury in an ex vivo rat lung model. 265 79

Intestinal ischemia-reperfusion injury is a common and important clinical event associated with the activation of an endogenous inflammatory response. Some of the mediators of this response may be involved in the pathogenesis of multiple organ system failure. The purpose of this study was to determine whether remote organ dysfunction--specifically, acute lung injury--occurs after intestinal ischemia-reperfusion injury. After an ischemia-reperfusion event in rat intestine, whole lungs were obtained for measurement of tissue adenosine triphosphate (ATP) and myeloperoxidase values, and evaluation of histologic condition. In addition, lung microvascular permeability was assessed by determination of the rate at which iodine 125-labeled bovine serum albumin sequestration in the extravascular compartment occurred. Lung tissue ATP levels were no different in sham-operated animals than in those that had undergone 120 minutes of intestinal ischemia. Within 15 minutes of gut reperfusion, however, lung ATP decreased from 3.82 +/- 0.27 to 1.53 +/- 0.90 x 10(-7) moles/50 mg tissue, p less than 0.05. Neutrophil accumulation in the lungs, estimated by tissue myeloperoxidase determination, increased sevenfold (0.13 +/- 0.02 to 0.97 +/- 0.25 units/gm, p less than 0.05) after 120 minutes of ischemia and 15 minutes of reperfusion. Lung microvascular permeability increased threefold after 120 minutes of intestinal ischemia and 120 minutes of reperfusion (0.10 +/- 0.01 vs. 0.35 +/- 0.05 [lung/blood counts per minute], p less than 0.05). Intestinal ischemia followed by reperfusion is associated with acute lung injury characterized by increased microvascular permeability, histologic evidence of alveolar capillary endothelial cell injury, reduced lung tissue ATP levels, and the pulmonary sequestration of neutrophils. These data confirm an acute lung injury associated with intestinal ischemia-reperfusion and suggest a possible pathogenic role for the neutrophil.
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PMID:Evidence for neutrophil-related acute lung injury after intestinal ischemia-reperfusion. 276 27

Whether patients with silent myocardial ischemia have a lesser mass of ischemic myocardium than patients with symptomatic ischemia is controversial. Forty-five patients with angiographic coronary artery disease (greater than or equal to 70% luminal diameter narrowing) were studied. All patients had ischemic patterns of myocardial uptake and clearance of the long-chain fatty acid perfusion/metabolic imaging agent iodine-123 phenylpentadecanoic acid after maximal exercise. Single-photon emission computed tomography was performed and 25 myocardial segments were analyzed using circumferential activity profile curves. The 21 patients with silent treadmill ischemia exercised longer than the 24 patients with painful treadmill ischemia (430 +/- 137 vs 337 +/- 96 seconds, p less than 0.01) and to a higher heart rate (138 +/- 21 vs 125 +/- 18 beats/min, p less than 0.05). Patients with treadmill silent ischemia had the same number of abnormally perfused myocardial segments as patients with painful treadmill ischemia (8.6 +/- 4.5 vs 6.5 +/- 4.1 segments, difference not significant) and the same number of reversibly ischemic myocardial segments (4.0 +/- 1.4 vs 4.2 +/- 3.0 segments, difference not significant). The angiographic severity and extent of coronary artery disease were similar in the 2 groups. Thus, in this selected group of patients, those with silent treadmill ischemia appear to have at least as great an extent of ischemic myocardium as patients with painful exertional ischemia.
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PMID:Estimation of jeopardized left ventricular myocardium in symptomatic and silent ischemia as determined by iodine-123 phenylpentadecanoic acid rotational tomography. 278 27

Radiographic techniques used to quantify coronary blood flow all require bolus injection of contrast material, which markedly alters the flow being measured. Newer nonionic contrast agents have been shown to have fewer adverse hemodynamic, inotropic, and rheologic effects compared with ionic media and it has been suggested that they might not substantially affect coronary blood flow. Six dogs were instrumented with electromagnetic flow probes and subendocardial ultrasonic crystals. Intracoronary injections of iohexol (300 mg/ml iodine) were administered to establish a relationship between the dose and rate of contrast injection and the effect on flow and regional myocardial function. Two and 4 ml volumes of iohexol were injected at 3 ml/sec; 4 ml volumes were administered at 1 and 4 ml/sec. The 2 and 4 ml volumes decreased coronary flow by a mean of 31% (p less than .01) and 77% (p less than .001). The 4 ml injection at 1 and 4 ml/sec 77% (p less than .001) and 69% (p less than .001). The magnitude of the fall in flow was directly related to the dose, and the rate at which the flow nadir was attained was directly related to the rate of injection. Decrements in fractional shortening were temporally delayed by several beats compared with the flow changes and showed mean decrements of 19% to 29%. The effects on regional myocardial function were independent of contrast volume. However, the degree of dysfunction was more profound with slower infusion rates, suggesting that prolongation of contrast-induced ischemia was a major modulating factor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The immediate effects of iohexol on coronary blood flow and myocardial function in vivo. 294 95

The experimental results from comparing the low-osmolar radiographic contrast media (CM) iohexol, iodixanol, and ioxaglate to the hyperosmolar CM sodium diatrizoate or barium for enteric follow-up examination in rats, suggest that low-osmolar CM are the better alternatives for use in examinations of obstructed small intestine. Excretion of iodine to the urinary bladder in rats with acute intestinal ischemia indicates that water soluble CM may be helpful in the discrimination between this serious disease and simple obstruction of the small intestine.
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PMID:Comparison of water-soluble contrast media and barium in rats with small bowel obstruction or ischemia. 319 48

Iodine-123 phenylpentadecanoic acid (IPPA) is a synthetic long chain fatty acid with myocardial kinetics similar to palmitate. Two hypotheses were tested in this study. The first hypothesis was that IPPA imaging with single photon emission computed tomography (SPECT) is useful in the identification of patients with coronary artery disease. Fourteen normal volunteers (aged 27 +/- 2 years) and 33 patients (aged 54 +/- 11 years) with stable symptomatic coronary artery disease and at least one major coronary artery with luminal diameter narrowing greater than or equal to 70% were studied with symptom-limited maximal exercise testing. The IPPA (6 to 8 mCi) was injected 1 min before the termination of exercise, and tomographic imaging was performed beginning at 9 min and repeated at 40 min after the injection of IPPA. Nine of the normal volunteers and 13 of the patients had a second examination performed at rest on another day. Using the limits of normal as 2 SD from the normal mean values, 27 of the 33 patients with coronary artery disease demonstrated abnormalities in either the initial distribution or the clearance of IPPA, or both. Nineteen of the 33 patients had a maximal variation of activity distribution of greater than or equal to 25% on the 9 min IPPA images. Twenty-two of the 33 patients had a maximal variation in IPPA washout greater than 17% and 17 had a washout rate less than or equal to 2%. There was good agreement between the location of significant coronary artery stenoses and abnormalities in the initial distribution and clearance of IPPA. The second hypothesis tested was that IPPA imaging is as or more sensitive and, therefore, complementary to thallium-201 imaging in the identification of exercise-induced ischemia in patients. Twenty-five of the 33 patients underwent both thallium-201 and IPPA tomographic imaging after symptom-limited maximal exercise testing. The amount of exercise performed by each patient during both studies was similar. Twenty-one of the 25 patients had abnormal IPPA tomographic studies, whereas 18 had abnormal thallium-201 tomographic studies (p = NS). The results of this study suggest the following conclusions: 1) iodine-123 phenylpentadecanoic acid imaging using single photon emission computed tomography and exercise provides a sensitive and relatively noninvasive method for identifying abnormalities in myocardial metabolism associated with significant coronary artery stenoses, and 2) iodine-123 phenylpentadecanoic acid is at least as sensitive as thallium-201 for this purpose using tomographic imaging and exercise testing.
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PMID:Iodine-123 phenylpentadecanoic acid and single photon emission computed tomography in identifying left ventricular regional metabolic abnormalities in patients with coronary heart disease: comparison with thallium-201 myocardial tomography. 325 60

A case of giant internal carotid ophthalmic aneurysm was presented. In order to clarify whether the patient could tolerate carotid occlusion, a balloon clamping test was performed. before surgery. The cerebral blood flow was measured using early imaging by single photon emission computed tomography (SPECT) with N-isopropyl-(iodine-123)-p-iodoamphetamine (123I-IMP). When the balloon clamping test was performed the tracer was injected, and scanning was performed 35 minutes after removing the catheter. This tracer enabled a "memory of blood flow" during temporary ischemia to determine the character of quick diffusion and slow wash out, that could not be performed by other methods of cerebral blood flow measurement. SPECT with 123I-IMP can simplify the measurement of cerebral blood flow during the balloon clamping test.
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PMID:A simple technique to measure regional cerebral blood flow during intravascular balloon clamping. 326 24


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