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)

In the current study we evaluated effluent blood from extremities of human patients undergoing reconstructive surgical treatment which is routinely accompanied by upper extremity exsanguination and application of a tourniquet. Following tourniquet release (reperfusion), there were immediate increases in the plasma levels of xanthine oxidase activity, uric acid, and histamine. Xanthine dehydrogenase activity was not detectable. Plasma also contained products consistent with the formation of oxygen-derived free radicals, namely hemoglobin and fluorescent compounds. Our data indicate in humans that ischemia-reperfusion events are associated with the appearance of xanthine oxidase activity and its products in the plasma effluent.
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PMID:Role of oxygen radicals in tourniquet-related ischemia-reperfusion injury of human patients. 179 87

Temperature increases membrane fluidity and decreases vascular resistance in isolated organs. Therefore, these studies were designed to determine if a rinse with warm buffer could increase survival time in the rat model of orthotopic liver transplantation by improving hepatic microcirculation. Brief periods of warm ischemia (3-8 min) did not damage the liver as indexed by minimal release of LDH. Survival of rats for 30 days was greater than 90% in this model when livers were stored for 1 hr in Ringer's solution; yet grafts stored for 8 hr in Euro-Collins solution and rinsed with 20 ml of cold (0-4 degrees C) Ringer's solution survived postoperatively only around 3 days. However, livers stored for 8 hr in Euro-Collins and rinsed with 20 ml of warm (37 degrees C) Ringer's survived longer than 30 days (i.e., permanently). Serum transaminase levels reached peak values around 6000 U/L one day postoperatively in the cold-rinsed group, and liver injury assessed histologically was substantial. Under these conditions, pulmonary infiltration of inflammatory cells was observed in about 23% of lung tissue examined and was associated with massive bleeding. Following a warm rinse, however, maximal SGOT levels and injury to both liver and lung were reduced significantly by 80-90% 24 hr postoperatively. Moreover, the warm rinse improved hepatic microcirculation. It accelerated blood flow into the liver approximately two-fold, as indexed by the half-time of changes in hemoglobin reflectance from the liver surface, improved the distribution of colloidal carbon in the organ observed macroscopically, and decreased vascular resistance by over 50%. These data support the hypothesis that a brief rinse of liver grafts with warm buffer markedly improves the hepatic microcirculation, leading to dramatic improvement in graft survival. This work demonstrates clearly that a brief warm rinse may be useful clinically in liver transplantation.
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PMID:Increase in survival of liver grafts after rinsing with warm Ringer's solution due to improvement of hepatic microcirculation. 187 93

Early postoperative hypoxemia may be due to a reduced functional residual capacity, hypoventilation, and ventilation-perfusion mismatch. These factors reduce the partial pressure of the arterial oxygen which ultimately reduces the oxygen transported to the tissues by decreasing the hemoglobin saturation. This may lead to cellular ischemia and death. Oxygen saturation may decrease during transport from the operating room to the postanesthesia care unit. The length of transport time in large operating suites may exceed 5 minutes, which may lead to inadequate oxygenation. This research used a pretest-posttest control group design on a convenience sample. Subjects were randomized into either the treatment or control group. At emergence, the SpO2 measured and the stopwatch started. The treatment group received 40% oxygen via a venturi mask during transport while the control group breathed room air. After a routine transport to the postanesthesia care unit, the SpO2 was again measured and the transport time was recorded. Oxygen saturation was found to be significantly greater in the group breathing supplemental O2 during transport.
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PMID:Effect of transport time and FiO2 on SpO2 during transport from the OR to the PACU. 188 86

Three isomeric series of 2-(aryloxy)-2-methylpropionic acids were prepared and studied for their ability to decrease the oxygen affinity of human hemoglobin A. The isomeric aryloxy groups included 4-[[(aryloyl)amino]methyl]phenoxy, 4-(arylacetamido)phenoxy, and 4-[[(arylamino)carbonyl]methyl]phenoxy. A total of 20 compounds were synthesized and tested. Structure-activity relationships are presented. Several of the new compounds were found to be strong allosteric effectors of hemoglobin. The two most active compounds are 2-[4-[[(3,5-dichloroanilino)carbonyl]-methyl]phenoxy]- 2-methylpropionic acid and the corresponding 3,5-dimethyl derivative. The latter two compounds have been compared to other known potent allosteric effectors in the same assay and show greater activity. Both compounds also exhibit a right shift in the oxygen equilibrium curve when incubated with whole blood. The new compounds may be of interest in clinical or biological areas that require or would benefit from a reversal of depleted oxygen supply (i.e., ischemia, stroke, tumor radiotherapy, blood storage, blood substitutes, etc.). They are also structurally related to several marketed antilipidemic agents.
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PMID:Allosteric modifiers of hemoglobin. 1. Design, synthesis, testing, and structure-allosteric activity relationship of novel hemoglobin oxygen affinity decreasing agents. 199 97

The vascular endothelium is important in the modulation of vascular tone via production of endothelium-derived relaxing and contracting factors. The abdominal aortas of five groups of rabbits were subjected to varying lengths of ischemia (0, 1, 2, 3, or 4 hours), removed, sectioned into transverse rings, and placed in tissue baths containing Krebs' buffer at 37 degrees C and aerated with 95% O2/5% CO2. After equilibration the rings were tested for endothelium-dependent vasodilation with methacholine and nonendothelium-dependent vasodilation with nitroprusside. Endothelium-dependent relaxation as elicited by methacholine was impaired at 3 and 4 hours of ischemia but was not significantly different at 1 and 2 hours as compared to control, whereas endothelium-independent vasodilation remained normal throughout the different periods of ischemia. The addition of 1 x 10(-6) mol/L rabbit hemoglobin reduced the time needed to demonstrate significant impairment of endothelial function to 2 hours. Endothelium-independent vasodilation was not affected by hemoglobin. We conclude that hemoglobin exacerbates ischemia vascular dysfunction in the rabbit aorta.
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PMID:Effects of ischemia and hemoglobin on vascular function in isolated rabbit aortas. 201 Sep 22

The influence of diltiazem and/or allopurinol on kidney microcirculation was studied in anaesthetized rats, which were subjected to 60 min unilateral renal ischemia followed by 60 min reflow. In histological sections capillary plasma flow patterns were determined based on the distribution of two different fluorochrome-labelled globulins administered i.v.. In the outer medulla (OM) of untreated postischemic kidneys labelling of the capillary network was greatly diminished. Tissue areas occupied by red blood cells increased 4-6 fold. During reperfusion massive penetration of red cells in the urine was demonstrated by the occurrence of hemoglobin in the urine. Maintenance of the rats on allopurinol-saturated drinking water for six days prior to the experiment (daily intake approximately 50 mg allopurinol/kg body wt) combined with the i.v. administration of diltiazem during the pre- and postischemic period (16 mg/kg body wt) resulted in an almost complete normalization of capillary plasma flow patterns in the OM. In this region tissue areas occupied by red blood cells were much lesser in extent than in the untreated controls. Furthermore, urine hemoglobin content after the combined drug regimen was largely decreased when compared to the untreated ischemic group. Effects of the treatment with either of the drugs alone were qualitatively similar, but significantly less pronounced. In conclusion, a synergistic effect of diltiazem and allopurinol in improving postischemic renal microcirculation is clearly evident, whereas no improvement in kidney function was demonstrable. This supports the hypothesis that disturbed microcirculation is not a prerequisite for the generation of the renal functional deterioration in the clamp-induced ischemia model in the rat.
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PMID:Effects of diltiazem and allopurinol in postischemic microcirculatory changes in the rat kidney. 206 Sep 98

In studying the side effects of sclerosants injected into the gastric submucosa in dogs (N = 7), we noted that 3 ml of absolute ethanol induced a large gastric ulceration. We describe the time course of change in the ulcer size, and suggest that such ulceration can be used for the endoscopic assessment of factors important in ulcer genesis and healing. Endoscopic reflectance spectrophotometric measurement of indices of mucosal hemoglobin concentration (IHB) and oxygen saturation (ISO2) were performed in a separate group of dogs (N = 4) with ethanol-induced gastric ulceration. We found a significant difference (p less than 0.05) in IHB and ISO2 immediately before (97 +/- 8 and 37 +/- 3, respectively) and after (138 +/- 7 and 21 +/- 5, respectively) the ethanol injection. At 24 hours after the ethanol injection, the IHB at the lesion margin (141 +/- 14) was significantly higher (p less than 0.05) than that at the adjacent mucosa (101 +/- 4), whereas the ISO2 measurements were not significantly different in these two locations, 34 +/- 2 and 31 +/- 2, respectively. We conclude that (1) injection of 3 mol of absolute ethanol into the submucosa of the canine stomach provides an animal model of gastric ulceration in which the ulcer can be examined repeatedly with the aid of the endoscope; (2) in this ulcer model, ischemia with congestion (increases IHB, decreases ISO2) precedes the development of gross mucosal ulcerations; and (3) the margin of the established ulceration in this model exhibits hyperemia (increases IHB, normal ISO2) which mimics that of a healing gastric ulcer.
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PMID:Endoscopic assessment of mucosal hemodynamic changes in a canine model of gastric ulcer. 207 Sep 80

Human blood is a very complex tissue. Therefore the idea of rediscovery its different cellular and plasmatic constituents would seem to be utopic. To be efficient the oxygen carrier, be it natural or by synthesis, must be stripped of antigenicity, be easily stockable and transportable. Thus these properties permit its use in urgent circumstances (accidents, natural disasters, war...), in those countries where there is a non existent or limited transfusional structure. This, under certain conditions, during very specific pathologies (localised ischemia for example). Among several hypotheses, they are two main lines of research that of "hemoglobin solutions" the oldest and the most physiological. This will be developed here in more lengthy terms due to our personal work on the subject. The second line of research concerns fluorocarbons, the most modern and artificial and without doubt better known to doctors and the public. 1. HEMOGLOBIN SOLUTIONS. Other than nephrotoxicity, which has proved affordable, research han revealed four large limitations with hemoglobin solutions (a high affinity for oxygen due to absence or loss of 2.3 DPG, a short half life due to vascular loss, rapid dimerisation and elimination of urine, insufficient concentration of prepared solutions (70 g/L) with as a result a weak oncotic pressure and oxygen supply, oxidation in methemoglobin). In order to overcome the two inconveniences, proposals were made to modify hemoglobin chemically, the idea coming from the putting into operation of potential analogues to or substitutes for 2.3 DPG which it is advisable to bring or to keep--by covalent bonding--near to the fixation site of the natural ligand. Thus our group has already deposed several patents and is now working on a complex hemoglobin-dextran benzine tetracarboxylate which appears promising. Today, due to the quality and reproduction of the results obtained on animals with chemically modified hemoglobin preparations clinical assays should be carried out soon. 2. FLUOROCARBONS. In this very different approach which uses totally synthetic compounds oxygen carrying can only be realised in dissolved form. Due to this fluorocarbons, even though they are remarkable solvents of gas, do not reach their full efficiency unless the patient breathes in a very rich oxygen atmosphere. This is therefore a considerable limiting factor. The other big problem is the insolubility of these compounds and therefore the need to emulsify them, but unfortunately these emulsions are difficult, if not impossible to stabilise.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Artificial blood in 1990: from a lifelong dream to today's reality]. 208 28

The influence of different drugs on ischemia induced oxygen free radical damage was examined in intestinal tissue of rats by determination of thiobarbituric acid reactive substances (TBARS). Some methodical aspects of this method were considered. Experiments were done with and without the use of polymerized stromafree hemoglobin (PHb) as an additional oxygen carrier. Reversible total occlusion of the superior mesenteric artery was performed for 90 min, reperfusion time was 2.5 hours. Despite higher O2 availability PHb did not increase the TBARS level any further. Superoxide dismutase with catalase; allopurinol; ciprofloxacin; and deferoxamine produced a highly significant reduction of TBARS, even if used together with PHb.
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PMID:Severity of oxygen free radical effects after ischemia and reperfusion in intestinal tissue and the influence of different drugs. 209 68

We examined the safety and utility of high-field MR in patients who had surgery for cerebral aneurysms of the vertebrobasilar system. Eighteen posterior (and three coincidental anterior) circulation aneurysms were treated. Twenty-one MR scans were obtained at a mean postoperative interval of 7.2 days. The mean size of the preoperative vertebrobasilar aneurysm was 2.2 cm; six were giant (greater than 2.5 cm) and eight were large (greater than 1.5, less than or equal to 2.5 cm). In 17 patients, Sugita nonmagnetic clips were used. In one other, a Drake tourniquet was used. No ill effects occurred from scanning with a high-field imaging unit at 1.5 T. The MR clip artifact was much less obtrusive than that on CT. In 11 cases, the aneurysm could be partially imaged postoperatively, mainly in very large aneurysms or in those treated by clipping the parent vessel. Of these, two revealed residual lumina on MR and nine looked completely thrombosed. Postoperative angiography showed that in four of the thrombosed-appearing aneurysms a residual lumen with a mean diameter of 1.0 cm had been missed. In the patient imaged after application of a Drake tourniquet, no artifact was seen, and a good assessment of progressive partial thrombosis was obtained. Evolution of the signal intensity of new aneurysm thrombus, in those minimally or not obscured by artifact, coincides with patterns previously described for hemoglobin in intracerebral hematomas. The earliest hyperintensity could be seen in either the periphery or the center of the new thrombus. All 15 patients examined with new postoperative deficits showed appropriate lesions, mainly small brainstem ischemic foci. Postoperative CT (performed in all but four of these patients) missed over 80% of these lesions, mainly owing to artifact from clip or bone. We conclude that MR is better than CT in the postoperative assessment of aneurysm patients, particularly in demonstrating small zones of ischemia. High-field MR scanning is safe if nonmagnetic surgical clips are used. MR is not accurate in assessing residual lumina.
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PMID:MR imaging after surgery for vertebrobasilar aneurysm. 210 98


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