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

Anterior segment ischemia changes can occur without detachment of any muscles. The most common cause of such ischemic changes of the anterior segment is the removal of too many rectus muscles in one operation. Twenty dog eyes and eight monkey eyes were subjected to the disinsertion and detachment of various combinations of extraocular muscles. They were sacrificed at intervals from 30 to 90 days. During the observation period, they were observed for gross and slit lamp changes. The enucleated eyes were studied microscopically for signs of ischemic and necrotic changes. Two patients who were studied, observed, and treated for anterior segment ischemia following muscle surgery are described. The changes which occur after muscle surgery are extensive and include corneal edema, cataract, chemosis, corneal changes, decreases in intraocular pressure, decreases in outflow or glaucoma and frank necrosis. The variables which lead to this reaction is described in detail. Also, some unanswered queries, such as the duration of the reaction and the time interval of the reaction after multiple muscle surgeries, are discussed.
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PMID:Production of anterior segment ischemia. 10 21

Anterior segment ischemic changes can occur without detachment of any muscles. The most common cause of such ischemic changes of the anterior segment is the removal of too many rectus muscles in one operation. Twenty dog eyes and eight monkey eyes were subjected to the disinsertion and detachment of various combinations of extraocular muscles. The dogs were sacrificed at intervals from 30 to 90 days. During the observation period, they were observed for gross and slit-lamp changes. The enucleated eyes were studied microscopically for signs of ischemic and necrotic changes. Two patients who were studied, observed, and treated for anterior segment ischemia following muscle surgery are described. The changes which occur after extraocular muscle surgery are extensive and include corneal edema, cataract, chemosis, corneal changes, decreases in intraocular pressure, decreases in outflow or glaucoma, and frank necrosis. The variables which lead to this reaction are described in detail. Also, some unanswered queries, such as the duration of the reaction and the time interval of the reaction after multiple muscle operations are discussed.
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PMID:Production of anterior segment ischemia. 41 49

Intravenous fluorescein is an accurate predictor of small bowel viability, but its effectiveness in assessing colon perfusion during aortic surgery has not been evaluated. Over a 10 year period 186 of 3,306 patients undergoing aortic reconstruction received 500 to 1000 mg of intravenous fluorescein intraoperatively to evaluate colon viability. Prior history of colectomy, hypogastric or mesenteric arterial occlusive disease, or ruptured aneurysm placed these patients at risk to develop ischemic colitis. Patients were operated on for aneurysmal disease (n = 94), occlusive disease (n = 66), or a combination of both (n = 26): 171 exhibited uniform normal perfusion patterns under Wood's lamp illumination, while in 11 it was "patchy." None of these patients developed full-thickness ischemic colitis (observed specificity: 100%). Fluorescence of the rectosigmoid was absent in four patients. One of these patients with a ruptured aneurysm underwent immediate sigmoid resection, while three underwent inferior mesenteric artery reimplantation. The fluorescein pattern subsequently normalized in two patients, but one underwent sigmoid resection for an expanding mesenteric hematoma. The second patient recovered without complications. The final patient continued to show a segmental sigmoid defect and postoperatively developed full-thickness injury requiring sigmoidectomy. During the same period 18 other patients developed transmural colon ischemia from 3,120 aortic reconstructions (0.6%), with a mortality rate of 56%. None had received intraoperative fluorescein. Selective use of intravenous fluorescein may reduce the mortality of ischemic colitis following aortic reconstruction.
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PMID:The role of intravenous fluorescein in the detection of colon ischemia during aortic reconstruction. 154 82

Aortic and renal vascular reconstruction often involve significant renal ischemia. Profound hypothermia during renal ischemia preserves renal tissue. However, in the clinical setting of vascular reconstruction specific attempts at cooling the kidney are often impractical, and renal ischemia frequently occurs at physiologic temperatures. This study demonstrates that minimal temperature changes during renal ischemia alter the functional and morphologic outcome. Rats anesthetized with halothane underwent a right nephrectomy and placement of a snare around the left renal pedicle for 45 minutes to produce renal ischemia. Seventy-five adult male Sprague-Dawley rats, weighing 250 to 350 gm were divided into three groups based on the body temperature maintained during renal ischemia (35 degrees C, 37 degrees C, 39 degrees C). Body temperature was continuously monitored with a rectal thermistor and maintained by adjustment of a heating pad and lamp. Two postischemic protocols were followed including a creatinine assessment protocol with blood samples collected at 24, 48, and 72 hours and a histologic assessment protocol with biopsy of the kidney at 30 hours. At 24 hours after ischemia plasma creatinine concentrations were increased in rats with elevated body temperatures (35 degrees C vs 37 degrees C; [p = 0.001], 37 degrees C vs 39 degrees C; [p = 0.150]). The 30-hour histologic assessment indicated a difference in morphologic outcome (35 degrees C vs 37 degrees C; [p = 0.063], 37 degrees C vs 39 degrees C; [p = 0.016]), with proximal tubular morphology being better maintained at lower temperatures.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Minimal physiologic temperature variations during renal ischemia alter functional and morphologic outcome. 156 May 50

Fornix conjunctival incisions in strabismus surgery may provide partial protection against anterior segment ischemia by preserving the perilimbal conjunctival-Tenon's circulation, which is disrupted with limbal conjunctival incisions. Six adult cynomolgus monkeys underwent tenotomies of three or four rectus muscles by making limbal conjunctival incisions in one eye and fornix incisions in the other. Iris fluorescein angiography and slit-lamp biomicroscopy were used to monitor changes. The eyes that had limbal incisions exhibited more severe anterior segment ischemic changes than the eyes that had fornix incisions in every instance of four rectus muscle surgery.
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PMID:A primate model of anterior segment ischemia after strabismus surgery. The role of the conjunctival circulation. 232 23

In 40 normal adult cynomolgus monkey eyes, recession of various recti in different combinations was done to evaluate their effects on the anterior segment. These procedures were done as primary, secondary, tertiary, and fourth procedures (each separated by several weeks or months), ultimately involving all four recti in the eyes. In 11 eyes, posterior ciliary arteries (PCAs) were occluded to determine its effects on the anterior segment. All eyes were examined by slit lamp, color photography, and fluorescein angiography of the anterior segment, and tonometry, before surgery and serially thereafter during the follow-up period. These studies showed that recession of two or three recti simultaneously in different combinations produced no serious permanent anterior segment changes, although initially in some of the eyes there was transient mild-to-moderate anterior segment ischemia. Recession of four recti simultaneously as a primary procedure produced serious permanent ocular and anterior segment changes; however, when this was done as a secondary or tertiary procedure after previous recessions of three or four recti, anterior segment changes were much fewer and milder than when it was a primary procedure. Occlusion of all the posterior ciliary arteries in itself produced no important changes in the anterior segment, but when combined with simultaneous recession of both the horizontal recti, it produced serious anterior segment changes. In the light of these findings, the pattern of arterial blood supply of the anterior segment is discussed.
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PMID:Anterior segment ischemia after recession of various recti. An experimental study. 244 29

Operations for intestinal ischemia are frequently done by veterinarians. In equine surgery those conditions commonly producing ischemia are intussusception, volvulus, bowel obstructions, and incarcerated hernias. In an attempt to predict intraoperative bowel viability after the restoration of circulation, a variety of adjuvant methods have been investigated. There is little question that of the techniques currently available, sodium fluorescein injected intravenously approaches the ideal in predicting nonviability in humans and in most animal models. Furthermore, it is safe, takes little operating time, is inexpensive, and is ubiquitously available; in addition, the only special equipment needed is a long-wave ultraviolet lamp. Reliance on this method would seldom result in nonviable bowel being left in situ. Furthermore, the use of fluorescein would minimize the unnecessary resection of viable intestine and, thereby, minimize the postoperative nutritional problems that may occur, especially in equines. The report of Sullins et al questions the accuracy of the fluorescein technique in predicting viability and nonviability in horses and also raises the question as to whether the prediction of viability, after the restoration of intestinal blood flow, also predicts normal intestinal function. Further investigations will be needed to confirm or refute these observations.
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PMID:Determination of intestinal viability. 267 Jan 9

We have tested whether small intraischemic variations in brain temperature influence the outcome of transient ischemia. To measure brain temperature, a thermocouple probe was placed stereotaxically into the left dorsolateral striatum of rats prior to 20 min of four-vessel occlusion. Rectal temperature was maintained at 36-37 degrees C by a heating lamp, and striatal temperature prior to ischemia was 36 degrees C in all animals. Six animal subgroups were investigated, including rats whose intraischemic striatal brain temperature was not regulated, or was maintained at 33, 34, 36, or 39 degrees C. Postischemic brain temperature was regulated at 36 degrees C, except for one group in which brain temperature was lowered from 36 degrees C to 33 degrees C during the first hour of recirculation. Energy metabolites were measured at the end of the ischemic insult, and histopathological evaluation was carried out at 3 days after ischemia. Intraischemic variations in brain temperature had no significant influence on energy metabolite levels measured at the conclusion of ischemia: Severe depletion of brain ATP, phosphocreatine, glucose, and glycogen and elevation of lactate were observed to a similar degree in all experimental groups. The histopathological consequences of ischemia, however, were markedly influenced by variations in intraischemic brain temperature. In the hippocampus, CA1 neurons were consistently damaged at 36 degrees C, but not at 34 degrees C. Within the dorsolateral striatum, ischemic cell change was present in 100% of the hemispheres at 36 degrees C, but in only 50% at 34 degrees C. Ischemic neurons within the central zone of striatum were not observed in any rats at 34 degrees C, but in all rats at 36 degrees C. In rats whose striatal temperature was not controlled, brain temperature fell from 36 to 30-31 degrees C during the ischemic insult. In this group, no ischemic cell change was seen within striatal areas and was only inconsistently documented within the CA1 hippocampal region. These results demonstrate that (a) rectal temperature unreliably reflects brain temperature during ischemia; (b) despite severe depletion of brain energy metabolites during ischemia at all temperatures, small increments of intraischemic brain temperature markedly accentuate histopathological changes following 3-day survival; and (c) brain temperature must be controlled above 33 degrees C in order to ensure a consistent histopathological outcome. Lowering of the brain temperature by only a few degrees during ischemia confers a marked protective effect.
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PMID:Small differences in intraischemic brain temperature critically determine the extent of ischemic neuronal injury. 369 28

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

A large number of experimental studies suggests that oxygen free radicals play a major role in the pathogenesis of the myocardial lesions observed during the sequence ischemia-reperfusion. The purpose of this study was to determine whether oxygen free radicals can induce thrombosis. In so doing we have developed a new experimental thrombosis model. Reproducible focal thrombosis has been achieved by irradiating mesenteric arterioles of rat for variable time with green filtered light issuing from a mercury lamp after systemic injection of different rose bengal doses. The number of emboli that remove in the blood (N), the duration of total occlusion (T) and the number of emboli per minute were then measured. As control, no rose bengal administration was done and the vessels were exposed to the filtered light. In comparison with this control, results clearly showed that free radicals always induced thrombosis and the induced thrombus was mainly composed of platelets. In this new thrombosis model induced by free radicals antithrombotic drugs (aspirin, 200 mg/Kg, heparin, 2 mg/Kg) and antioxidants (vitamin C, 10 and 20 mg/Kg, allopurinol, 200 and 300 mg/Kg, vitamin E, 500 and 1000 mg/Kg) have been tested. Results have shown that only heparin and vitamin E had an antithrombotic effect on thrombus formation induced by free radicals. This model should be useful in studying the effects of different drugs and could lead to new treatment modalities for ischemic accident and other cardiovascular diseases.
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PMID:Experimental thrombosis model induced by free radicals. Application to aspirin and other different substances. 749 98


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