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

Cerebral blood volume, hemoglobin saturation and the cytochrome a, a3 redox state were monitored simultaneously by using three wavelengths of light in the near infrared portion of the spectrum for transillumination of the intact skull of rats. The changes in these parameters following incomplete cerebral ischemia were assessed in Wistar and Long-Evans rats submitted to carotid ligation. Another group of Wistar rats was submitted to vertebral + carotid occlusion. The experiments, performed under N2O/O2 anesthesia, showed that in all three groups carotid occlusion induced a decrease in blood volume, Hb saturation and a reduction of cyt. a, a3. However, the cytochrome redox state tended to normalize during ischemia as a consequence of higher O2 extraction from blood. The primary finding of this study was the marked hyperoxidation of cyt. a, a3 which occurred after reestablishing of the carotid blood supply, in spite of a secondary post-ischemic hypoperfusion of the brain. Although uncoupling of oxidative phosphorylation cannot be excluded the dissociation between blood supply and metabolism could well be due to ischemia-induced hypermetabolism of the central nervous tissue. In view of the marked oxidation of cyt. a, a3 during the reperfusion period as compared with the small extent of its reduction during the ischemic episode, the data also support the hypothesis that under steady state conditions in vivo, cytochrome oxidase is mainly reduced.
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PMID:Incomplete cerebral ischemia in the rat: vascular and metabolic changes as measured by infrared transillumination in vivo. 631 78

Blood present in the tissue distorts the results obtained during measurement of antibiotic tissue levels. The greater the blood supply to the tissue, the bigger the error when tissue levels are measured. The examination of tissue removed during temporary intraoperative ischemia is an alternative to the indirect mathematical method of correcting errors of blood level measurement. This technique was tested by determining tissue concentrations after i.v. injection of 4 g mezlocillin and 2 g oxacillin. The tissue was removed during operations on limbs after the application of an Esmarch's bandage. Determination of hemoglobin in ischemic tissue confirmed exsanguination so that the 6-((R)-2-[3-methylsulfonyl-2-oxo-imidazolidine-1-carboxamido]-2-phenylacetamido )-penicillanic acid-Na (mezlocillin) and 5-methyl-3-phenyl-4-isoxazolylpenicillin (oxacillin) concentrations determined corresponded to the actual tissue levels. The concentrations of mezlocillin and oxacillin in fat, skin, tendon, muscle, ganglion, aponeurosis, tumour, ligament, subcutis, synovial fluid, epineurium and serum are given in the text.
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PMID:Antibiotic concentrations in blood and tissue. Intraoperative ischemia as a model for the determination of tissue concentrations using mezlocillin and oxacillin as examples. 645

Ischemic change of cerebral energy metabolism and catecholamine have already been discussed largely using biochemical quantitative assay. However, regional change and their correlation are not well understood. In the present study, the ischemic regional change of cerebral energy metabolism and catecholamine were investigated in gerbils and histochemical method. Adult either sex mongolian gerbils, weighing 50-100 g, were anesthetized with ether and the left carotid artery was ligated. After observation of clinical symptoms, the brain was frozen in situ by pouring liquid N2 after 30 min and 60 min of ischemic insult. The frozen brain was sectioned with precooled saw in the coronal plane. The brain section were placed in liquid N2 bath and illuminated with 366 nm light (UV) from a 200 watt mercury lamp and Corning filter 5840. NADH fluorescence was recorded photographically through Corning filter 3387 and 5562. Also UV reflectance was recorded through Corning filter 5840 to observe quenching effect of hemoglobin. Regional change of catecholamine was observed in the same frozen brain processed with Falck-Hillarp method. According to neurological abnormalities following left carotid ligation, animals were divided into three groups; symptomatic, borderline and asymptomatic. The intensity and distribution of tissue NADH fluorescence were closely correlated to the clinical symptoms. In the symptomatic group, both in 30 min and 60 min of ischemia, homogeneously and markedly increased fluorescence was observed in the ipsilateral temporal cortex, caudate nucleus, hypothalamus and dorsolateral thalamus. Columnar mild increase of NADH fluorescence was seen in the ipsilateral parietal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Regional change of brain energy metabolism and catecholamine in the early stage of experimental cerebral ischemia--histochemical study]. 673 86

In acute myocardial infarction the effect of oxygen administration in modifying infarct size is uncertain. To evaluate this as well as the effects of moderate hypocarbia, four groups of anesthetized dogs were studied experimentally for 2 hours after coronary branch ligation: group I (controls; room air, normal blood gases): group IIA (FIo2 50%, normal Paco2); group IIB (FIo2 50%, low Paco2); and group IIC (50% oxygen given after ligation, normal Paco2). In addition to hemodynamics, the effect of differing blood gas patterns on hemoglobin-oxygen affinity (P50) and ischemic alterations of myocardial electrolyte and water content were evaluated. Hemodynamic changes among the four groups included decreases in LV ejection fraction and cardiac output. The latter was more pronounced in the oxygen treated groups with proportionately greater increases in systemic resistance. P50 increased in all groups, indicating decreased hemoglobin-oxygen affinity; in group IIC this increase was significantly greater than in group I. In all groups an analysis of central and border areas of myocardial ischemia showed loss of potassium and gain of sodium and water, but no beneficial effect on this result by oxygen administration pre or post ligation could be demonstrated. On the contrary, among those dogs administered oxygen the ischemic changes appeared more pronounced than in the control group. Moderate hypocarbia did not modify the myocardial electrolyte and water change. The results of this study do not support the hypothesis that oxygen administration can favorably modify the myocardial changes of ischemia, at least early in the course of myocardial infarction.
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PMID:Effects of oxygen administration and alteration in arterial PCO2 on ischemic myocardial changes following experimental coronary artery ligation. 681 24

We quantitated hemorrhage associated with reperfusion after varying periods of myocardial ischemia and examined the flow characteristics that accompany reperfusion hemorrhage. Anesthetized dogs were reperfused after 2, 6 or 24 hours of circumflex occlusion. A control group underwent coronary occlusion without reperfusion. Radioactive microspheres were injected before and 5 minutes and 24 hours after reperfusion. The papillary muscles were analyzed for hemoglobin content, flow during myocardial ischemia and flow early and 24 hours after reperfusion. Myocardial creatine kinase activity was assayed to determine the severity of myocardial necrosis in the papillary muscles. Hemorrhage into the posterior papillary muscle was dependent upon the duration of coronary artery occlusion. Posterior papillary hemoglobin averaged 14 mg/g in the 2-hour group, 28 mg/g in the 6-hour group and 36 mg/g in the group reperfused 24 hours after occlusion, compared with 8.7 mg/g in the control group. Myocardial hemorrhage was associated with severe depression in myocardial CK and marked depression in flow to the ischemic area (i.e., collateral flow) during the occlusion. Early reflow averaged 112 ml/min/100 g in the 2-hour group, 61 ml/min/100 g in the 6-hour group and only 5.8 ml/min/100 g in the 24-hour group. Therefore, myocardial hemorrhage induced by reperfusion of the acutely ischemic myocardium is associated with severe ischemia during occlusion and severe myocardial necrosis, but does not depend upon the magnitude of early reflow. Myocardial hemorrhage may occur even though initial reflow values are markedly decreased.
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PMID:The time course and characterization of myocardial hemorrhage after coronary reperfusion in the anesthetized dog. 683 66

Blood substitutes are being developed that will provide oxygen-transporting capabilities as well as volume replacement. Perfluorochemical and hemoglobin solutions have potential clinical use. A perfluorochemical blood substitute, Fluosol-DA 20%, is being used in clinical trials in several countries. These blood substitutes are not capable of totally replacing the need for blood transfusions but could be used temporarily in situations where blood is contraindicated or not available. They may be useful for a wide range of clinical conditions other than blood replacement, such as impending tissue ischemia. Before large-scale clinical use of these products is realized, more information is needed about drug efficacy and safety so that intelligent decisions can be made about indications for this type of transfusion therapy.
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PMID:Canadian Red Cross lecture. Current concepts of oxygen-transporting blood substitutes. 704 93

DT, a 63-year-old white male with insulin-dependent diabetes mellitus and severe peripheral vascular disease, was admitted with a five-day history of vague abdominal pain and diarrhea. On the day of admission he vomited three times, was noted to have a bloody stool, and came to the emergency room. DT denied hematemesis, fever, or chills. He had bilateral leg amputations and had sustained three myocardial infarctions, the last one 15 months before this admission. He had never experienced symptoms of abdominal angina. Of significance was his history of congestive heart failure, mitral regurgitation, and atrial fibrillation. His medications on admission included digoxin 0.25mg per day, furosemide 40mg per day, and NPH insulin 15 units per day. On admission to the hospital his oral temperature was 38 degrees C, pulse was 90/min, respiratory rate was 24/min, and blood pressure was 134/80mmHg. Abdominal examination revealed a distended abdomen with hypoactive bowel sounds and mild tenderness. Chest x ray revealed cardiomegaly. The electrocardiogram demonstrated atrial fibrillation. A plain film of the abdomen was positive for gallstones and edema of the bowel wall (thumb-printing). Laboratory results included blood urea nitrogen 48mg%, creatinine 1.2mg%, hemoglobin 18g/dl, and hematocrit 52.9%. White blood cell count was 11,900 cells/cc with 33% polymorphonuclear leukocytes, 47% bands, 8% lymphocytes, 11% monocytes, and 1% atypical lymphocytes. The prime considerations for differential diagnosis were mesenteric ischemia and infectious gastroenteritis. While it was appreciated that mesenteric ischemia, if present, might warrant surgical intervention, the risk of anesthesia itself in this patient was felt by his attending physicians to exceed 30%. Furthermore, the clinical findings were only "suggestive" of mesenteric eschemia. They were certainly not "diagnostic." In view of this dilemma, a consultation with the Division of Clinical Decision Making was requested.
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PMID:Abdominal pain, atherosclerosis, and atrial fibrillation. The case for mesenteric ischemia. 716 38

Oxygenated Fluosol-43 cardioplegia (CP), a perfluorocarbon with high oxygen solubility, was compared with crystalloid and oxygenated blood cardioplegia. Potassium in each CP was 25 mEq/l. Thirty perfused rabbit hearts in three groups of 10 hearts each underwent 100 minutes of global ischemia at 20 degrees C, followed by 45 minutes of reperfusion at 37 degrees C. During ischemia, CP was given every 20 minutes. With each CP injection, increases in myocardial oxygen tension were recorded using mass spectrometry and oxygen consumption (MVO2) was calculated. Left ventricular function was assessed before and after ischemia by measuring isovolumic developed pressure and dP/dt with an intraventricular balloon. Intramyocardial PO2 increased by 19.6 +/- 1.8 mm Hg in the Fluosol CP group, 0.4 +/- 0.1 mm Hg in the crystalloid CP group and 1.5 +/- 0.3 mm Hg in the blood CP group (p less than 0.001, Fluosol CP vs crystalloid CP and blood CP). MVO2 with each CP injection, expressed as ml O2/100 g dry weight, was 203.8 +/- 7.0 for Fluosol CP, 20.4 +/- 1.2 for crystalloid CP and 39.2 +/- 4.3 for blood CP (p less than 0.001 Fluosol CP vs crystalloid CP and blood CP). Recovery of maximal dP/dt after 45 minutes of reperfusion, expressed as a percentage of preischemic control, was 75.6 +/- 4.0% for Fluosol CP, 60.9 +/- 5.5% for crystalloid CP and 53.4 +/- 3.7% for blood CP (p less than 0.02 Fluosol CP vs blood CP and crystalloid CP). These data clearly show that the use of Fluosol cardioplegic solution enhanced oxygen delivery and use compared with blood and crystalloid cardioplegic solutions. The marked increase in intramyocardial oxygen and MVO2 with each injection of Fluosol CP shows that there is effective aerobic metabolic activity during ischemia, which may explain the improved functional recovery. The failure of blood CP to afford similar protection can be explained by a decreased oxygen release from hemoglobin due to the leftward shift of the oxygen-hemoglobin dissociation curve with hypothermia.
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PMID:Superiority of perfluorocarbon cardioplegia over blood or crystalloid cardioplegia. 724 32

Chronic, excruciatingly painful ulcerations of the lower extremities in patients with homozygous sickle cell anemia (HbSS) present a frustrating clinical problem for the reconstructive surgeon. Despite adequate wound care and skin grafting, there is a dismally high incidence of recurrence. Furthermore, there is a paucity of reliable locoregional fasciocutaneous, muscle, and myocutaneous flaps in the ankle region. Free-tissue transfer has become the procedure of choice for reconstruction of the lower third of the leg. However, in sickle cell anemia, does the obligate period of flap ischemia inherent in free-tissue transfer inevitably doom a flap to failure? We present our multidisciplinary experience over 55 months with five free flaps in four homozygous sickle cell anemia patients 21 to 38 years old who had chronic nonhealing leg ulcerations. Special perioperative measures included exchange transfusion to lower hemoglobin S to below 30 percent, maintaining the hematocrit at 31 to 35 percent, intraoperative flap washout and perfusion with warm heparinized saline-dextran solution, administration of dextran and aspirin intraoperatively and postoperatively, prophylactic topical and systemic anti-Pseudomonas antibiotics, supplemental oxygen, and warm ambient room temperature. Flaps included the latissimus dorsi muscle (two patients), the temporoparietal fascia (one patient), and "split" omentum for bilateral lower limb salvage (one patient). Successful free-tissue transfer was accomplished in all patients. One patient suffered gradual partial occlusion of the microcirculation by sickled erythrocytes following a transient hypothermic, hypotensive episode. Sufficient flap tissue survived to permit skin grafting with an excellent result. Pseudomonas infection occurred in two patients (three flaps).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lower limb salvage by microvascular free-tissue transfer in patients with homozygous sickle cell disease. 756 93

Reperfusion after continuous or discontinuous ischemia has a bearing on clinical interventions. An important question is the washout of metabolites after periods of diminished energy state of the myocardial cell. We therefore set out to determine the washout of adenosine and its metabolites after periods of ischemia in an experimental set-up which allowed non-destructive monitoring of the cellular energy state and cytosolic pH over consecutive time intervals. Isolated rat hearts were perfused with hemoglobin-free saline in a nuclear magnetic resonance spectrometer equipped for 31P NMR spectroscopy of phosphorus-containing metabolites, which could be measured over 3-min time blocks. The response of the heart when subjected to 18 min of continuous ischemia and subsequent reperfusion was compared with that when subjected to three 6-min periods of ischemia separated by 3-min periods of reperfusion. The mechanical performance of the hearts, oxygen consumption and efflux of adenosine and its metabolites were measured. The consecutive ischemic periods produced no evidence of preconditioning as judged from the cellular energy state, although the mechanical recovery was better than after continuous ischemia. During the repetitive ischemia/reperfusion protocol the efflux of adenosine was smaller, although the efflux of combined adenylate catabolites did not differ from that after continuous ischemia. The results do not support the view of adenosine being a major effector in the phenomenon of preconditioning.
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PMID:Efflux of adenosine and total adenylate catabolites during alterations of the cellular energy state. An NMR study of continuous and discontinuous ischemia. 757 74


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