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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Embolism of the right middle cerebral artery regularly failed to induce clinical or electrical seizure activity during acute ischemia in primates. This negative correlation casts some doubt on the popular interpretation of seizures at the outset of clinical stroke as evidence of cerebral embolism.
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PMID:Laboratory note. EEG changes after acute cerebral embolism. 5 70

The relationship between increase in water content in ischemic brain and levels of regional blood flow has been studied in 11 primates. Flows were recorded using the method of hydrogen (2-minute) clearance, from a total of 128 electrodes in cortex and white matter, and a gradation of ischemia was produced by middle cerebral occlusion transorbitally. The flows were reduced in the area of densest ischemia from control levels of 12.0 +/- 12.0 ml/100g/min to 7.0 +/- 5.4 ml/100g/min, with lesser decreases over the remainder of the ischemic hemisphere. Water content was measured in cortex and white matter, in regions topographically related to those of flow measurements, by densitometric assessment using precalibrated kerosene/bromobenzine columns. The average water content of cortex in regions remote from ischemia was 797.4 +/- 5.8 mg/gm and in white matter 708.5 +/- 8.2 mg/gm. Significant increases in water content (comparing corresponding regions of the two hemispheres) of up to 11.4 +/- 7.5 mg/gm were demonstrated in the most ischemic cortical areas. A gradient of water increase was evident in the ischemic hemisphere, increases water content being greatest in the opercular zone and least in the parasagittal area. Significant differences in white matter water content between the 2 hemispheres were demonstrated only in the most densely ischemic areas in the current experiments where ischemia was limited to 93 +/- 20 mins in the 11 animals without reperfusion. The relationship between ischemic density and water content increase showed that significant increases in water content occurred in regions where terminal flows had been below 20 ml/100g/min, indicating that accumulation of water in ischemic brain begins at flow values comparable to those associated with the failure of synaptic transmission, higher than those associated with failure of the ionic pump of the cell. Possible pathophysiological mechanisms are discussed.
Stroke
PMID:Ischemic brain edema following middle cerebral artery occlusion in baboons: relationship between regional cerebral water content and blood flow at 1 to 2 hours. 10 19

We measured total and regional cerebral blood flow (CBF, rCBF) and cerebral metabolic rate (CMR) of oxygen (O2), glucose (G), and lactate (L) levels for 4 h after 16 min global brain ischemia in rhesus monkeys with and without post-insult thiopental therapy. Eleven monkeys weighing 4-5 kg anesthetized with 1 percent halothane, 66 percent nitrous oxide and 33 percent oxygen, were subjected to 16 min global brain ischemia by a combination of trimethaphan hypotension (to a mean arterial pressure of 50 torr) and a high pressure (1500 torr) neck tourniquet. Post-ischemia, 7 monkeys were untreated (controls) and 4 received thiopental 90 mg/kg infused intravenously over 60 min, beginning at 5 min post-ischemia. Total CBF and rCBF were measured by continuous monitoring of cerebral venous (torcula) and parietal-occipital (external scintillation) 133Xe activity, respectively, after intra-innominate artery injection of 500 micronCi 133Xe in saline. In control monkeys, hyperemia in rCBF, but not in total CBF was observed at 6-7 min post-ischemia, whereas both total CBF and rCBF increased in thiopental treated monkeys. The hyperemia in thiopental treated monkeys coincided with an increase in CMRG without a proportional increase in CMRO2 or lactate levels. Indeed, CMRO2 was depressed in the first 30 min post-ischemia. At 30 min post-ischemia, CMRO2 rose to twofold greater than pre-ischemia in control monkeys, but only to pre-ischemic levels in thiopental treated monkeys. The data suggest that thiopental therapy improves distribution of brain blood flow and brain glucose uptake early post-ischemia and depresses CMRO2 later post-ischemia.
Stroke
PMID:Brain blood flow and metabolism after global ischemia and post-insult thiopental therapy in monkeys. 11 95

Abdominal aortic aneurysmectomy is being performed with progressively lower operative mortality and morbidity. Three hundred thirty seven patients have had elective aneurysm repair since 1954. Factors affecting mortality and morbidity in the last 108 cases are analyzed. Seventy-four per cent of patients had pre-existing disease, either cardiac, pulmonary, renal, cerebrovascular, diabetes mellitus, or hypertension. Six patients died following operation, a mortality rate of 5.5%. One died of pulmonary and 5 of cardiac causes. No patient died of renal failure or required dialysis. A signficant feature of management is the regimen of fluid therapy using dextrose in lactated Ringer's solution during and after operation to minimize hypotensive and renal complications. No patient developed a wound infection, graft infection, wound dehiscence, stroke, or intestinal ischemia. Serious postoperative complications were largely cardiac or pulmonary. Despite recent liberalization of indications for operation, comparative figures show continued reduction in operative mortality from 17% during 1954-1961, or 7.4% during 1962-1967, to 5.5% in the 1968-1974 era. This declining mortality is related to earlier diagnosis using non-invasive methods (sonogram), simplified operative techniques, improvement in fluid management, innovations in cardiopulmonary therapy, and recognition and proper handling of unusual manifestations of aortic aneurysms.
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PMID:Surgical management of abdominal aortic aneurysms: factors influencing mortality and morbidity--a 20-year experience. 12 60

The effect of ischemia on catecholamine and 5-hydroxytryptamine (5-HT) levels in brain cortex was examined in the gerbil stroke model. Unilateral common carotid artery occlusion produced bilateral decrease in cortical dopamine levels in gerbils both symptomatic and asymptomatic of cerbral ischemia. The 5-HT progressively decreased only in the occluded hemisphere of ischemic animals. In p-chlorophenylalanine (PCPA)-treated gerbisl, dopamine decreased only in the occluded hemisphere of symptomatic animals, but norepinephrine became decreased bilaterally compared with controls. The 5-HT decrease was twice that seen in untreated animals. It is suggested that these results indicate initial release together with reduced synthesis of monoamines in ischemic brain. The incidence of ischemia induced by carotid occlusion decreased from 44% to 26% in PCPA-treated animals, which also suggests that depletion of 5-HT available for neuronal release prior to the induction of ischemia may reduce stroke incidence by limiting impairment of collateral vasocapacitance. PCPA pretreatment did not influence the development of edema in the occluded hemisphere of ischemic animals once ischemia was established.
Stroke
PMID:Cathecholamine and 5-hydroxytryptamine levels in ischemic brain. Influence of p-chlorophenylalanine. 14 Apr 80

Reduce nicotinamide adenine dinucleotide (NADH) fluorescence was recorded from an avascular area on the squirrel monkey cortex prior to, during, and after focal incomplete ischemia. By using the instrumentation described, stable recordings were obtained free from hemoglobin artifact and with only minimal photodecomposition. Pentobarital was compared to urethane and halothane as the anesthetic agent and was found acceptable for these types of studies in the dosages used. NADH levels were constant prior to ischemia, increased during ischemia, returned to pre-ischemic levels after restoration of blood flow, and then increased greatly at death produced by anoxia. The use of the infrared microscope for semiquantitative measurements of cortical blood flow throughout the duration of these acute studies was investigated and found to the reliable.
Stroke
PMID:Reduced nicotinamide adenine dinucleotide fluorescence and cortical blood flow in ischemic and nonischemic squirrel monkey cortex. 1. animal preparation, instrumentation, and validity of model. 16 72

The fluorescence of reduced nicotinamide adenine dinucleotide (NADH) from cerebral cortex was measured before, during, and after middle cerebral artery (MCA) occlusion and then at death of the animal. In normal cortex, NADH remained constant throughout a wide range of variations in blood pressure and Paco2. In ischemic cortex, NADH levels were higher in hypovolemic hypotensive animals than in normotensive normovolemic animals. Neither hypercapnia nor hypocapnia was effective in decreasing NADH in regions of ischemia, but the latter was associated with a degree of hypotension that interfered with interpretation of data. NADH returned to normal with restoration of flow, supporting the reversibility of this degree of ischemia. The high levels of NADH at death, compared to those during ischemia, are consistent with incomplete ischemia in this model of cerebral infarction.
Stroke
PMID:Reduced nicotinamide adenine dinucleotide fluorescence and cortical blood flow in ischemic and nonischemic squirrel monkey cortex. 2. effects of alterations in arterial carbon dioxide tension, blood pressure, and blood volume. 16 73

Cyclic AMP levels were measured in brains of 21 cats after occlusion of a middle cerebral artery by a transorbital approach. Brain samples for determination of cAMP by a protein binding radioassay were obtained from the ischemic and contralateral temporal lobes before sacrifice, 1, 3, and 24 hours after occlusion of the right middle cerebral artery. At 1 hour, no difference between the 2 sides was observed; a mean of 17.4 pmoles/mg protein was observed from the side of the occlusion and 18.9 pmoles/mg protein from the contralateral side. At 3 hours, a mean value of 8.9 pmoles/mg protein on the ischemic side and a level of 21.7 pmoles/mg protein on the contralateral side were observed. At 24 hours, the cAMP level on the ischemic side remained below the nonischemic side; the values obtained were 13.7 pmoles/mg protein compared to 27.9 pmoles/mg protein compared to 27.9 pmoles/mg protein. These changes in cAMP as early as 3 hours after the onset of ischemia, when such a lesion is reversible, may indicate that in initial step in the alteration of cellular metabolism following ischemia is due to membrane perturbation and altered production of this second messenger.
Stroke
PMID:Alterations of cyclic AMP in cerebral ischemia. 20 82

The study includes 50 patients with severe, stable angina who have undergone the saphenous vein bypass operation. Patients were evaluated preoperatively and postoperatively with regard to exercise tolerance, incidence of stress-induced agina, ST-segment changes of ischemia, and ventricular function as indicated by stroke work index (LVSWI) and ejection fraction. Comparisons were made between patients with complete revascularization (CR) and patients with postoperative residual ischemia (RI). Results revealed that exercise duration improved significantly in both the CR and RI groups. In the CR group, angina and ischemic ST changes were completely eliminated. In the RI group, there was a 25 percent incidence of stress angina and a 50 percent incidence of ischemic ST-segment changes. In neither group was the ejection fraction significantly different from preoperative values. LVSWI decreased significantly in both groups postoperatively.
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PMID:Evaluation of saphenous vein bypass surgery with multistage treadmill test and ventricular function studies. 30 89

As has been shown in a large number of animal experiments, there is a marked difference between the systolic-to-diastolic flow ratios of the right coronary artery and the left. We examined these ratios in 107 patients who were undergoing aorto-coronary bypass surgery as treatment for coronary artery disease. After cessation of cardio-pulmonary bypass, the blood flow was recorded electromagnetically in a total of 126 venous grafts to the right or to the branches of the left coronary arteries. From these tracings, the following magnitudes were calculated: coronary stroke flow per heart beat, systolic and diastolic stroke flows, mean flow, systolic and diastolic flows. The ratio of the systolic to the diastolic stroke flow was 0.30 +/- 0.17 for the branches of the left coronary artery (n = 79) and 0.61 +/- 0.30 for the right coronary artery (n = 47). The ratio of systolic to diastolic flow was found to be 0.46 +/- 0.25 (branches of the left coronary artery) and 1.01 +/- 0.62 (right coronary artery), respectively. All these values differ statistically on a probability level of p less than 0.001. In principle, our results agree with those of canine experiments. The considerable variation of the individual values of the systolic-to-diastolic flow ratios can be explained by the following: 1. the variability of the pattern of coronary blood supply in man; 2. the actual right and left ventricular pressures; 3. the extent of stenoses present; 4. the degree of myocardial impairment due to ischemia. These factors combined determine the actual value of the extravascular (myocardial) component of the peripheral coronary resistance, which is most effective during systole.
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PMID:[Dependence of blood flow in human aorto-coronary bypass grafts on the extravascular resistance (author's transl)]. 30 35


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