Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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

Although numerous interventions have been shown to exert a salutary effect on the ischemic myocardium, the severity of ischemia generally has been measured by indirect techniques. In the present investigation the effect of ischemia on intramural carbon dioxide tension (PmCO(2)) was measured directly in the open-chest, anesthetized dog with a mass spectrometer during repetitive 10-min coronary artery occlusions separated by 45-min periods of reflow; simultaneously, regional myocardial blood flow in the ischemic area was measured by (127)Xenon washout. In all dogs the increase in PmCO(2) from before to 10 min after the first occlusion (DeltaPmCO(2)) exceeded that during subsequent occlusions. In those dogs not receiving an intervention (controls), DeltaPmCO(2) during the third occlusion was similar to that during the second occlusion. When propranolol, hyaluronidase, and nitroglycerin were administered to different groups of dogs before the third occlusion, each caused significantly smaller elevations in DeltaPmCO(2) than those occurring during the control second occlusion, and the combination of all three interventions induced the smallest increase in DeltaPmCO(2). Regional myocardial blood flow rose with hyaluronidase and was unchanged with propranolol, nitroglycerin, and the three drugs in combination. In contrast to these beneficial interventions, isoproterenol infused with the third occlusion caused a higher DeltaPmCO(2) than during the control second occlusion. It is concluded, first, that interventions that modify the severity of ischemia can be evaluated by measuring intramural carbon dioxide tension; second, that propranolol, hyaluronidase, and nitroglycerin reduce ischemic injury, whereas isoproterenol increases it; and third, that the combination of propranolol, hyaluronidase, and nitroglycerin exerts an additive beneficial effect on ischemia.
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PMID:Assessment of the efficacy of interventions to limit ischemic injury by direct measurement of intramural carbon dioxide tension after coronary artery occlusion in the dog. 10 16

The effect of intravenous infusion of 10 per cent glycerol on regional cerebral blood flow (using hydrogen bolus and Xenon-133 (133Xe) clearance methods) and metabolism was investigated in 57 patients with recent cerebral infarction. Hemispheric blood flow (HBF) increased, together with increase in regional cerebral blood flow (rCBF) and cerebral blood volume (rCBV), in foci of brain ischemia. Hemispheric oxygen consumption (HMIO2) decreased together with hemispheric respiratory quotient. Systemic blood levels of glucose, lactate, pyruvate, and triglycerides also increased after glycerol while free fatty acids (FFA) and inorganic phosphate (Pi) decreased. Hemispheric glucose consumption was unaltered after glycerol so that hemispheric glucose to oxygen ratio tended to rise. Pyruvate and lactate production by brain was unchanged. Glycerol moved across the blood brain barrier into brain and cerebrospinal fluid (CSF). Release of FFA and Pi from infarcted brain was reversed by glycerol. Total phosphate balance was maintained actoss brain both before and after glycerol infusion. Triglycerides increased in CSF after glycerol, originating either from cerebral blood or as a result of lipogenesis in cerebral tissue. The EEG Recording and neurological status of the patients improved despite decreased brain oxygen consumption. Results of this study suggest that after intravenous infusion of 10 per cent glycerol in patients with recent cerebral infarction, glycerol rapidly enters the CSF and brain compartments and favorably affects the stroke process in two ways: first, by redistribution of cerebral blood flow with increase in rCBF and rCBV in ischemic brain secondary to reduction in focal cerebral edema; and second glycerol may become an alternative source of energy either by being directly metabolized by the brain, or indirectly, by enhancing lipogenesis, or by both processes. Involvement of glycerol in lipogenesis with esterification to accumulated FFA might lead to improved coupling of oxidative phosphorylation, a hypothesis that fits the finding of improved neuronal function despite further decrease in cerebral hemispheric oxygen consumption.
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PMID:Circulatory and metabolic effects of glycerol infusion in patients with recent cerebral infarction. 109 Mar 93

FOS and JUN proteins are transcription factors thought to be involved in coupling neuronal excitation to target gene expression. Cortical infarction of consistent size and location was produced by irradiating the rat brain with Xenon light through the intact skull for 20 min following systemic injection of the photo-sensitizing dye, rose bengal. To investigate the time course and distribution pattern of five cellular immediate early gene (IEG)-encoded proteins after focal ischemia, the expression of c-FOS, FOS B, c-JUN, JUN B and JUN D was studied immunocytochemically in sham-operated control animals and at different postischemic time intervals up to 24 h. A separate group of animals was pretreated with the non-competitive N-methyl-D-aspartate (NMDA) antagonist MK-801. Photochemically induced focal ischemia caused a rapid induction of FOS and JUN proteins in the entire ipsilateral cortex apart from the ischemic focus. Immunoreactivity in the ipsilateral subcortical gray and white matter and in the entire contralateral hemisphere was indistinguishable from control animals. Individual IEG-encoded proteins were sequentially induced with increased levels of immunoreactivity persisting for different time periods up to 24 h. c-FOS, FOS B, c-JUN and JUN B exhibited a characteristic distribution pattern as reflected by different staining intensities in individual cortical layers. The rapid IEG induction in the entire ipsilateral sensorimotor and limbic structure-associated cortices after photochemically induced infarction most likely reflects spreading depression caused by ischemia and mediated by NMDA receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Induction of FOS and JUN proteins after focal ischemia in the rat: differential effect of the N-methyl-D-aspartate receptor antagonist MK-801. 146 67

We observed an increase in cerebral blood flow (CBF) for control of pain but were otherwise normal. Based on that observation, we implanted stimulators for cervical spinal cord stimulation (cSCS) in three patients who had symptomatic cerebral ischemia. Two had severe basivertebral occlusive disease and one had bilateral carotid occlusive disease. In all three cases, cSCS alleviated the symptoms of ischemia. Xenon-CBF studies or single-photon emission computer tomography (SPECT) showed increased CBF in response to cSCS. Although no mechanism clearly responsible for this remarkable therapeutic efficacy can be proposed yet, further clinical trials of cSCS for inoperable cerebral ischemia may be justified.
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PMID:Treatment of cerebral ischemia with electrical stimulation of the cervical spinal cord. 170 26

Cerebral blood flow (CBF) and central conduction time (CCT) were recorded from 58 subarachnoid hemorrhage patients and from 49 age-matched controls. CBF was calculated following Xenon inhalation and CCT was determined from somatosensory evoked potentials (SSEP's) following median nerve stimulation. Each patient had a CT scan on the day of admission which was graded from I-IV. CBF, CCT and neurological grade (Hunt and Hess classification) were concomitantly recorded 1, 4, 7 and 14 days after subarachnoid hemorrhage. Mean CBF was highest in patients with neurological grades I and II (48.6 +/- 12.3 and 48.1 +/- 10.3 ml/100gm/min respectively) and lowest in patients with neurological grade IV (37.3 +/- 9.6 ml/100gm/min). Patients in neurological grade I or II had mean CBF and CCT measurements that were significantly different from those obtained from patients in neurological grade IV (P less than 0.05). Neurological grade and CT scan grade correlated with CBF (P less than 0.0001) better than CCT (P = 0.015). Unexpectedly low CBF's from patients in neurological grades II and III (less than 37 and less than 31 ml/100gm/min respectively) failed to significantly prolong CCT suggesting CCT is unable to detect marginal ischemia. A significant correlation between CBF and CCT occurred only when CBF was less than 30 ml/100gm/min (R = 0.75, P = 0.05). It appears that prolonged CCT is associated with a drop in CBF only when CBF drops below a certain threshold.
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PMID:Correlation between cerebral blood flow, somatosensory evoked potentials, CT scan grade and neurological grade in patients with subarachnoid hemorrhage. 178 9

The importance of cerebral ischemia produced by carotid clamping during carotid endarterectomy remains controversial. In an effort to determine the importance of cerebral ischemia during carotid endarterectomy, 369 patients undergoing 431 consecutive carotid endarterectomies were studied by Xenon-133 (133Xe) clearance and electroencephalogram (EEG) monitoring. None of the patients was shunted during the procedures. The severity of ischemia as indicated by 133Xe clearance from the ipsilateral hemisphere during 20 to 30 minutes of carotid occlusion did not predict the appearance of complications in this group of patients (chi 2 = 1.417; P = 0.841). There was a highly significant relationship between the depth of cerebral ischemia as demonstrated by 133Xe clearance and the appearance of abnormalities on the EEG (chi 2 = 42.043, P less than 0.0001). In the subgroup of patients developing abnormalities as shown by EEG, there was a negative correlation (chi 2 = 17.495; P less than 0.002) between reduction in blood flow and the appearance of complications, in that the higher the blood flow during occlusion the more likely the patient developing EEG changes would develop complications.
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PMID:The importance of cerebral ischemia during carotid endarterectomy. 196 3

Measurement of arterial flow is a very old practice, and intra-arterial recordings of pressure and flow have long served as a reference for experimental studies (fig. 1). The definition of a hemodynamic state is inconceivable unless these two parameters are associated. The electromagnetic method using an intra-arterial sensor measures pulsatile flow. Now, technological advances have led to the appearance of other methods providing measurement of mean (plethysmography) and nonpulsatile flow. As a result, there has been considerable confusion between mean arterial and pulsatile arterial flow (Fig. 2). Various studies have emphasized the physiological importance of pulsatile arterial flow and thus the interest in measuring it. The recording of mean flow has often proved disappointing because values are comparable in groups of normal subjects and those with arterial disease. Mean arterial flow can be measured by isotopic methods and plethysmography. Xenon-133 clearance is the isotopic method most often used. Since determination of microcirculatory flow at rest proved of no use, it was necessary to add a hyperemia test reactive to ischemia to differentiate patients with artery disease from normal subjects. Methods involving technetium and thallium have been little used since they require the presence of a nuclear medicine center and are not easily reproducible. There are numerous plethysmographic methods, but only those are studied here which allow measurement of arterial flow. Plethysmography by venous occlusion measures arterial flow by recording the increase in limb volume. The sensor is a mercury strain gauge.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Measurement of arterial flow in the limbs: plethysmography, isotopes, electromagnetic methods]. 217 49

Cerebral blood flow (CBF) was studied in 4 patients with acute reversible ischemia (RIND). To test the ischemic areas' vasoreactivity, CBF was measured by the Xenon-133 inhalation method, before and after acetazolamide injected intravenously. At the baseline CBF study, 3 patients presented hypoperfused areas while one patient had increased CBF over the affected hemisphere. The acetazolamide test, showed in this latter case a "steal phenomenon" while in the other 3 an increase of perfusion was evidenced, in areas of normal flow, as well as in areas with reduced flow. These results suggest that in the acute phase of patients with RIND, when brain regions of hypoperfusion and neurological signs are still present, the vasomotor response may be preserved.
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PMID:Acetazolamide effects on cerebral blood flow in acute reversible ischemia. 278 40

The present study reports cerebral blood flow (CBF) measurements in 11 patients during attacks of classic migraine (CM)--migraine with aura. In 6 and 7 patients, respectively, cerebral vascular reactivity to increased blood pressure and to hypocapnia was also investigated during the CM attacks. The Xenon-133 intraarterial injection technique was used to measure CBF. In this study, based in part on previously published data, methodological limitations, in particular caused by scattered radiation (Compton scatter), are critically analysed. Based on this analysis and the results of the CBF studies it is concluded: During CM attacks CBF appears to decrease focally in the posterior part of the brain to a level around 20 ml/100 g/min which is consistent with a mild degree of ischemia. Changes of CBF in focal low flow areas are difficult to evaluate accurately with the Xe-133 technique. In most cases true CBF may change 50% or more in the low flow areas without giving rise to significantly measurable changes of CBF. This analysis suggests that the autoregulation response cannot be evaluated in the low flow areas with the technique used while the observations are compatible with the concept that a vasoconstrictive state, unresponsive to hypocapnia, prevails in the low flow areas during CM attacks. The gradual increase in size of the low flow area seen in several cases may be interpreted in two different ways. A spreading process may actually exist. However, due to Compton scatter, a gradual decrease of CBF in a territory that does not increase in size will also appear as a gradually spreading low flow area when studied with the Xe-133 intracarotid technique.
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PMID:Blood flow and vascular reactivity during attacks of classic migraine--limitations of the Xe-133 intraarterial technique. 201 68

Regional cerebral blood flow (rCBF) during hypertension and hypercapnia was studied in 33 patients with putaminal hemorrhage, using a single photon emission CT by means of Xenon 133 inhalation method. The results obtained were as follows: 1) A significant relationship was obtained between the impairment of autoregulation, CO2 reactivity and the degree of cerebral ischemia, i. e., in most cases, these vascular responses were impaired in cases of ischemia showing the rCBF decrease over 30 to 40% of normal values. However, there were particular cases with cerebral ischemia of over 30 to 40% in which autoregulation seemed to be preserved in the acute stage, which was considered to be the similar phenomenon as so called "false autoregulation". 2) The cerebrovascular responses such as autoregulation and CO2 reactivity were preserved in cases of less than 50 ml of hematoma volume. In cases with 50 to 74 ml of hematoma volume however, autoregulation and CO2 reactivity were mostly impaired, especially in the affected hemisphere rather than the non-affected, in the period of 1 to 2 months from the onset. Furthermore, the impairment was also involved in both hemispheres if the hematoma was over 75 ml in volume. 3) The cerebrovascular responses were markedly impaired in the region of basal ganglia of the affected hemisphere which corresponded well to the hematoma site. 4) There was a close correlation between the cerebrovascular responses and the activity of daily life (ADL), i. e, the prognosis might be poor in cases with global impairment, but which seemed to be rather good in cases with local impairment. It might be concluded, from the results mentioned above, that the study of autoregulation and CO2 reactivity is probably significant in estimating the pathogenesis and the treatment of cerebral ischemia following hypertensive putaminal hemorrhage.
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PMID:[A study of cerebrovascular autoregulation and CO2 reactivity in putaminal hemorrhage]. 310 23


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