Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Current forms of brain monitoring, such as electroencephalography (EEG), have had limited clinical utility. The EEG records spontaneous cerebrocortical activity and thus is an indirect indicator of metabolic demand and, to a lesser extent, an indicator of mismatch of supply versus demand. Ischemia modulates EEG activity in ways that can usually be detected, but EEG patterns can be similarly modulated by many other factors, including temperature and pharmacologic manipulation. This in vivo study in physiologically monitored animals evaluated the use of correlated optical spectroscopy, performed with an instrument having a fiberoptic light-guide bundle in contact with the cerebral cortex, for the simultaneous monitoring of cerebrovascular oxygen availability and intracellular oxygen delivery. A highly specific monitor of cerebral intracellular oxygen supply, the cerebrocortical intramitochondrial NADH redox state, was monitored in vivo with a fluorescence technique. Absorption spectroscopy was used concurrently to monitor hemoglobin content (blood volume) and oxygen saturation in the microcirculation. Correlated changes in optical signals from cerebrocortical NADH and hemoglobin were studied in a swine model (n = 7) of nitrogen hypoxia. Measurements were made at four wavelengths with a time-division, multiplexed fluorometer/reflectometer. Because the NADH fluorescence signal at 450 nm is affected by local changes in blood volume, a "corrected" fluorescence signal is usually calculated. In previous studies, where only two wave lengths have been measured, attempts at correction were based on reflectance at the excitation wavelength (366 nm). We compared estimators of changes in microcirculatory blood volume using reflection at two wavelengths: 366 nm and 585 nm, the wavelengths for maximum and isobestic absorption. The results of the studies were as follows: (1) during transient hypoxia, NADH and local hemoglobin saturation signals changed in concert with arterial pulse oximetry, with changes in NADH lagging behind changes in saturation by an average of 5.3 seconds; (2) after hypocapnic ventilation to a mean PaCO2 of 20.2 +/- 0.8 mm Hg, NADH increased by 11.5 +/- 8.7% (as compared with maximal change during anoxia), local hemoglobin saturation decreased by 7.7 +/- 6.4%, and local blood volume decreased by 12.5 +/- 13%, while arterial SpO2 was unchanged; (3) our two measures of local blood volume were closely correlated during carbon dioxide perturbations, but poorly correlated during hypoxic perturbation; and (4) NADH fluorescence provided a more rapid, sensitive indicator of oxygen deprivation than did the EEG. During transient hypoxia, EEG changes occurred 57.4 +/- 10.4 seconds after the onset of decline in local hemoglobin saturation, after NADH had completed 50% of its maximal increase.
 ...
PMID:Correlated, simultaneous, multiple-wavelength optical monitoring in vivo of localized cerebrocortical NADH and brain microvessel hemoglobin oxygen saturation. 149 28

Mucosal hemodynamics (by reflectance spectrophotometry) and mucosal damage (by histologic examination) following acute colonic ischemia were evaluated in different anatomic locations in the colon of anesthetized rats. The reflectance spectrophotometer provides an index of mucosal hemoglobin concentration (IHB) and an index of oxygen saturation of hemoglobin (ISO2). The patterns of ischemia without congestion (decreases IHB, decreases ISO2) during superior mesenteric artery occlusion, and ischemia with congestion (increases IHB, decreases ISO2) during portal vein occlusion, previously demonstrated in the stomach and duodenum, are also applicable to the colon. The significant linear correlations between changes (as percent of baseline) in IHB, ISO2, and hydrogen gas clearance suggest that changes in these indices are adequate indicators of changes in colonic mucosal perfusion. Superior mesenteric artery ligation produced significant reductions in both indices, and an increase in damage in the mucosa of the cecum, transverse colon, splenic flexure, and left colon, but not the rectum. Inferior mesenteric artery ligation produced only slight reduction in these indices and minimal damage only in the mucosa of the splenic flexure. These results support the hypothesis that the superior mesenteric artery is more important than the inferior mesenteric artery in maintaining colonic perfusion and colonic mucosal integrity in the rat.
 ...
PMID:Superior mesenteric artery is more important than inferior mesenteric artery in maintaining colonic mucosal perfusion and integrity in rats. 150 83

We studied the effect of inhibition of oxyradical formation and of endogenous glutathione (GSH) depletion on lesion formation in the gastrointestinal tract in a modified rat hemorrhagic shock model (1 h hypotension and 1 h reperfusion). Allopurinol, an inhibitor of xanthine oxidase, did not protect against lesion formation. This suggests that oxygen radicals generated from xanthine oxidase may not be the major cause of injury under these conditions of prolonged 'ischemia'-reperfusion. Phorone (diisopropylideneacetone), a GSH depletor, decreased mucosal GSH levels in the corpus, duodenum and small intestine, and also significantly reduced lesion formation histologically in the corpus, antrum, duodenum and small intestine. However, there was no significant differences in mucosal blood flow (as estimated by changes in mucosal hemoglobin concentrations and oxygen saturation of mucosal hemoglobin) in the corpus, antrum, duodenum and small intestine between phorone-pretreated and control rats. We conclude that phorone decreased mucosal GSH concentrations and exerted a protective effect against hemorrhagic shock-induced gastrointestinal mucosal lesions. The protective effect appears to be independent of mucosal blood flow.
 ...
PMID:Effect of phorone and allopurinol on ischemia-reperfusion injury in gastrointestinal mucosa of the rat. 150 63

Neonatal encephalopathy of early onset, plausibly related to hypoxia and ischemia remains one of the main problems in perinatal medicine. Efforts are necessary to find new non-invasive methods for assessing brain oxygenation. Near-infrared spectroscopy (NIRS) provides information on the concentrations of the oxygenated and reduced forms of hemoglobin, as well as the redox state of cytochrome aa3. Different important variables can be derived through hemoglobin measurement, such as cerebral blood volume and flow, and the responses of these to changes in pCO2. Changes in cytochrome aa3 may provide immediate information on intracellular oxygen utilization. Various studies have shown the feasibility of NIRS in preterm infants. Methodological and technical problems of this method are discussed.
 ...
PMID:Near-infrared spectroscopy in newborn infants. 151 51

We tested retinal vessel autoregulation in 16 sickle cell patients and 6 controls by computer-assisted measurements of constriction of the superior and inferior temporal veins and arteries after pure oxygen breathing. Compared to the controls and corrected for age, we found a decrease of vasoconstriction in three of the four vessels measured in the sickle cell group, which was statistically significant only for the superior temporal artery (P 0.009). The number of patients was too small to allow a separate analysis of possible contributory factors within the sickle cell group, such as sickle cell hemoglobin subtype and extent of retinal ischemia. Our findings indicate a factor not yet well known in the pathophysiology of sickle cell disease: an abnormality of local microvascular control.
 ...
PMID:Retinal vessel autoregulation in sickle cell patients. 152 10

Eighteen hemodialysis patients with the diagnosis of mesenteric ischemia (MI), admitted to the Renal Service in the last 5 years, were retrospectively reviewed. All patients, 10 males and 8 females, average age 66.3 +/- 8.6 years, were complaining of acute abdominal pain without other specific clinical or laboratorial findings, had their diagnosis confirmed during laparatomy, with ischemic involvement of the ileocecal/ascendant colon area in 14 cases and the small bowel in 4. Noteworthy was the high incidence of previous dialysis-induced hypotensive episodes (10/18), the presence of leukocytosis (13/18), the high average hemoglobin level of 9.4 gr/dl, and the constant finding of non-occlusive MI. Average time in-hospital was 15.4 days (2 to 30) and the mortality--88% (16 patients). The growing incidence of MI mostly of the non-occlusive type, and its grim prognosis, calls for an early diagnosis of functional ischemic colitis, and the adoption of preventive action to avoid bowel infarction.
 ...
PMID:[Mesenteric ischemia in hemodialysis]. 160 63

Ischemic hepatitis is not an uncommon complication of reversible severe hypotension or cardiac failure. The prognosis usually is determined by the cause of the initial hypotension or cardiac failure, rather than the subsequent hepatic dysfunction. We report a retrospective analysis of nine patients with ischemic hepatitis in which previously unreported clinical and biochemical abnormalities are noted. The clinical and biochemical course of the patients were reviewed until recovery or death from ischemic hepatitis. All the patients had a rapid striking elevation of aspartate aminotransferase, and lactic dehydrogenase, with an equally rapid resolution of these parameters. Abnormal serum glucose levels occurred in six patients (none of whom had a prior carbohydrate intolerance). Insulin therapy was given to three patients for a limited period. Renal impairment was manifest in all nine patients, and it resolved spontaneously within 10 days. Altered mental status was detected in six patients; the changes reverted to normal within 7 days of their onset. A preexisting anemia (hemoglobin less than 11.0 g/dl) was noted on admission in four patients, and it did not appear to potentiate the manifestations of the hepatic ischemia. We conclude that ischemic hepatitis should be anticipated in all patients with a recent history of systemic hypotension. It should be considered in the differential diagnosis of patients with unexplained hepatitis; the early massive rise in lactic dehydrogenase, the rapid fall in transaminases, and the early mild/moderate renal failure strongly suggest ischemic hepatitis. Patients with ischemic hepatitis can manifest reversible renal failure, mental confusion, and hyperglycemia which may require insulin for its control.
 ...
PMID:Ischemic hepatitis: widening horizons. 848 Jul 56

The present study investigates whether oxygenated perfluorochemicals protect the gastric mucosa against hemorrhage-induced stress ulceration. The influence of oxygenated perfluorochemicals on both macroscopic and microscopic lesion formation, gastric intramural pH, index of oxygen saturation and index of hemoglobin saturation of the gastric mucosa was studied. To assess the severity of gastric mucosal ischemia, intramural pH was directly measured using a pH sensitive microelectrode and indirectly by utilizing hollow viscus tonometry, and the indices of oxygen saturation and hemoglobin saturation were measured by reflectance spectrophotometry. Oxygenated perfluorochemicals (30 ml/kg/h) significantly protected the gastric mucosa against both gross (lesion index 0.85 +/- 0.2 vs 2.23 +/- 0.31) and microscopic (lesion index 0.52 +/- 0.02 vs 2.04 +/- 0.03) injuries. This protection was associated with a significantly decreased acidification of the mucosa during shock (intramural pH 7.24 +/- 0.02 vs 6.97 +/- 0.02) and significantly increased oxygen saturation of the gastric mucosa (30 +/- 6 vs 5 +/- 2). These data indicate that topical oxygenated perfluorochemicals protect the gastric mucosa against mucosal damage provoked by hemorrhagic shock, and this protection seems to be mediated by an increased oxygen saturation of the gastric mucosa. Tonometry and reflectance spectrophotometry thus are able to predict the critical level of gastric mucosal ischemia.
 ...
PMID:Experimental studies on the prediction and prevention of stress ulcers using tonometry, reflectance spectrophotometry and oxygenated perfluorochemicals. 178 13

By a spectrophotometrical method, the oxygenation and relative concentration of hemoglobin in the skin of the forefoot was determined in 40 patients with advanced peripheral arterial occlusive disease. While the Hb-saturation at rest was hardly different from normals, leg elevation provoked a marked decrease of both parameters, especially in patients with critical ischemia. In these patients, reactive hyperemia was markedly delayed and impaired. External heat application failed to cause a hyperemic saturation increase in 14 patients and produced a decrease in 8 patients, 6 of whom experienced an infavourable clinical outcome. The method seems specially suited to assess states of severe ischemia.
 ...
PMID:[Reflection spectrophotometry determination of cutaneous hemoglobin saturation in patients arterial occlusive diseases]. 178 13

A patient with long-standing bilateral circumferential lower extremity sickle cell ulcerations refractory to conservative management was successfully treated with bilateral free latissimus muscle transfers. This report confirms the value of free tissue transfer in the treatment of these difficult skin ulcerations. Exchange transfusions that brought the SS hemoglobin below 30% were crucial to the prevention of sickling in the microcirculation of the flap during its obligate period of ischemia. Furthermore, they protected the flap during a period of ischemia that exceeded 4 hours following a postoperative arterial thrombosis. In the presence of severe thrombocytosis associated with sickle cell disease, prophylactic treatment with aspirin may be of significant value.
 ...
PMID:Bilateral lower limb salvage with free flaps in a patient with sickle cell ulcers. 179 45


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>