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

Open-angle glaucoma in the blacks is generally thought to be a more malignant disease than in whites in terms of response to therapy and subsequent visual loss. An increased incidence of unsuspected sickle trait and undetected sickling may have contributed to these patients' optic nerve ischemia, progressive field loss and need for surgery. A homoglobin electrophoresis was done on 40 black patients who required filtering surgery for uncontrolled open-angle glaucoma. Only 2 of the 40 patients (5%) had sickle trait as determined by the hemoglobin electrophoresis. In a matched group of 40 controls, only 3 patients (7.5%) had sickle trait. Therefore, there does not appear to be an increased incidence of sickle trait in black patients requireing filtering surgery.
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PMID:The incidence of sickle trait in Blacks requiring filtering surgery. 90 Jul 26

Coagulation mechanisms were examined in the dog after a 70 per cent hepatectomy and the additional effect of varying periods of ischemia on the liver remnant. Dogs were submitted to a 70 per cent partial hepatectomy, and the liver remnant was rendered ischemic by occluding the vascular inflow. Portal decompression during ischemia was accomplished by allowing portal venous flow through the lobes subsequently resected. Dogs in the control group, those undergoing hepatectomy alone and those undergoing hepatectomy together with 60 minutes of ischemia time exhibited a fall in hemoglobin and hematocrit values, a transient leukocytosis, a small increase in kaolincephalin clotting time and a decline in platelet count but no significant thrombocytopenia. Prothrombin time was changed in dogs undergoing hepatectomy, but this was not affected by ischemia. The characteristic rise in plasma fibrinogen postoperatively was abolished, and fibrinogen levels were lower in dogs undergoing hepatectomy alone and fell significantly in dogs subjected to 30 to 60 minutes of ischemia of the liver remnant. Factors V and VII were decreased after hepatectomy, and Factor V was more severely reduced after 30 to 60 minutes of ischemia. There was no overt bleeding tendency. In ten dogs, the liver remnant was subjected to ischemia for 75 minutes. Four of these died within three days of operation, two with severe hypoglycemia and two with postoperative bleeding. All six surviving dogs exhibited gross coagulation defects. Prothrombin time rose, kaolin-cephalin clotting time increased and platelets fell to a greater degree than in any of the other dogs. Plasma fibrinogen level showed a profound fall, as did Factor V, the magnitude of these changes being greater than after a shorter period of ischemia. Factor VII was also decreased, but this did not appear to be related to the ischemic interval. In the clinical situation in which intrinsic coagulation mechanisms are shown to be impaired, treatment with Factor V and VII concentrates may be the best way of correcting the coagulation defect.
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PMID:The mechanism of impaired coagulation after partial hepatectomy in the dog. 93 55

Mongrel dogs were subjected to cardiopulmonary bypass with hemodilution and to normothermic anoxic arrest for 30 minutes, to study the subepicardial and the subendocardial myocardial ultructure and the DPTI/TTI ratio. "No-reflow phenomenon" was demonstrated in the myocardium after cardiopulmonary bypass, associated with normothermic anoxic arrest. No-reflow phenomenon was a contributing factor to subendocardial ischemia in the normotrophied ventricle after open-heart surgery. Severe hemodilution with hemoglobin less than 5.0 g% resulted in irreversible damage in both myocardial layers.
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PMID:Ultrastructural change in myocardium subsequent to ischemic cardioplegia "no-reflow phenomenon". 103 15

In 17 patients who underwent openheart surgery with cardiopulmonary bypass using heparinized fresh blood for priming the heart-lung machine the following investigations were done: Blood samples taken at different periods of surgery were assayed for total calcium (Catot), ionized calcium (Ca++), magnesium (Mg), hemoglobin, total pasma proteins, and the acid-base-status. Considering the different kinds of cardiopulmonary bypass the patients were divided into three groups: In the first group the results ofsurgical procedure with and without hemodilution perfusion were compared. During hemodilution perfusion Catot decreased markedly whereas Ca++ remained nearly constant. In the second group the influence of different calcium concentrations of the prime solution on Catot and Ca was tested. A low calcium content of 2.8 mEq/1 lowered Catot and Ca++ to subnormal levels. In the third group results of Mg-induced cardioplegia were compared with findings during surgical procedure with anoxic cardiac arrest. A remarkable increase of magnesium at the perfusion onset could be observed. Magnesium remained within the upper level of normal range until surgery end and decreased to normal values in the postoperative stage. Since energy requirements of the arrested heart and thus the velocity of ATP-breakdown during ischemia are closely related to the Ca++ concentration of the extracellular space low plasma calcium levels are considered to be advantageous during cardiopulmonary bypass. Only at the end of partial bypass before the heart fully takes over circulating work a sufficient calcium substitution is recommended.
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PMID:Divalent ions and myocardial function during cardiopulmonary by-pass (CPB). Changes of total calcium, ionized calcium, and magnesium in plasma. 119 32

We have developed the multiprobe assembly (MPA) by which metabolic, ionic and electrical activities can be monitored from the surface of the brain. In the present study we included optical fibers for the monitoring of intracapillary hemoglobin oxygenation by use of the Erlangen Microlight Guide Spectrophotometer (EMPHO-I) from the surface of the gerbil brain. The newly developed MPA provides simultaneous information about oxygen delivery (oxydeoxy Hb), tissue pO2 level, as well as the intracellular oxygen balance (intramitochondrial redox state). The ionic homeostasis was evaluated by monitoring extracellular K+ and Ca2+ activities reflecting the permeability changes of cation channels as well as the activities of Na+,K(+)-ATPase and other ion linked transport processes. The electrical activities were monitored by a bipolar electrocortical surface probe and DC steady potential. The subjects of the present study were Mongolian gerbils (Meriones unguiculatus) anesthetized and operated according to our routine techniques. After 30 min of recovery from the operation each gerbil was exposed to a short anoxia, graded hypoxia, ischemia as well as spreading depression. The results can be summarized as follows: 1. A clear correlation was recorded between the changes in oxydeoxy Hb spectra, tissue pO2 level and oxidation-reduction state of intramitochondrial NADH under oxygen deficiency situations (hypoxia, ischemia). 2. Blood volume changes under various perturbations monitored by various probes (366 reflectance and EMPHO-I) correlated very well with each other. 3. The degree of inhibition of Na+,K(+)-ATPase induced by oxygen deficiency could be interpreted by changes in extracellular levels of K+ measured by the surface mini-electrode. 4. Brain stimulation induced by spreading depression mechanism led to transient changes in ionic homeostasis and increase in energy requirements. The major HbO2 response was an increase in oxygenation due to the large CBF increase as monitored by the laser Doppler flowmeter. 5. Changes in oxy-deoxy Hb under fast scanning of 500-600 nm during 2-3 seconds of bilateral carotid arterial occlusion provided an indirect index for tissue O2 consumption.
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PMID:Multiparametric evaluation of brain functions in the Mongolian gerbil in vivo. 133 23

Hemodynamic parameters of six groups of guinea-pig hearts were studied by the working heart technic of Neely. Three groups were respectively perfused with: Krebs-Henseleit, purified native hemoglobin 1gm/dl and hemoglobin conjugated to dextran benzene tetracarboxylate 1 gm/dl. Three other groups were perfused under the same conditions except that after 30 mn of perfusion, 10 mn of total ischemia were produced followed by 30 mn of reperfusion with the previous solutions. All solutions contained 10 g/l of BSA. Hearts perfused with Hb solutions without ischemia or after ischemia show better parameters than with Krebs-Henseleit. These observations suggest that contrary to previously published results, purified Hb and more, dextran-BTC-Hb appear to be perfusable and are less deleterious for heart than saline without hemoglobin.
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PMID:A potential blood substitute from carboxylic dextran and oxyhemoglobin. III. Evaluations by perfusion of normal and ischemic guinea-pig heart. 138 44

A modified hemoglobin solution (<pyridoxylated hemoglobin>-<polyoxyethylene> conjugate solution, PHP solution) has very interesting characteristics such as oxygen-carrying property without corpuscular components. Experimental use of the PHP solution has shown promising possibilities as a perfusate relevant to organ transplantations. 1) Elongation of warm ischemic time in canine kidneys: Dogs survived even with the unilateral kidneys which had been exposed up to 4.5 hour warm ischemia and, thereafter, perfused with the PHP solution. 2) Elongation of perfusion preservation period of canine livers: Dogs survived with the transplanted livers which had been perfused for 48 hours with the PHP solution. 3) Successful perfusion of rat small intestine: Lewis rat intestines perfused and preserved for 12 hours with the PHP solution showed a higher survival rate compared with those with Collins or UW solution. 4) Removal of antibodies: By exchange transfusion with a total of 30-60 ml of the PHP solution, a Lewis rat hematocrit lowered to 5% while IgG went down to nil from 8970 mg/dl, IgA to 28 mg/dl from 118 mg/dl and IgM to 190 mg/dl from 897 mg/dl. This technique is expected to be applicable for removal of the naturally existing antibodies in xenotransplantation.
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PMID:Modified hemoglobin solution as possible perfusate relevant to organ transplantation. 139 75

Hemodilution has had limited success as a treatment of cerebral ischemia. When using a nonoxygen binding fluid, the therapeutic efficacy of hemodilution-induced increases in CBF are offset by concomitant decreases in oxygen content. The effect of hemodilution, with diaspirin alpha-alpha cross-linked hemoglobin (DCLHb), on CBF during middle cerebral artery occlusion was assessed. Rats were hemodiluted to one of the following hematocrits (Hct): (a) 44/Hct, (b) 37/Hct, (c) 30/Hct, (d) 23/Hct, (e) 16/Hct, or (f) 9/Hct. After 10 min of ischemia, CBF was determined with 14C-iodoantipyrine. Coronal brain sections were evaluated for areas with a CBF of 0-10 and 11-20 ml 100 g-1 min-1. In addition, oxygen delivery was calculated. In the center of the ischemic zone, both areas of low CBF were less in the 30/Hct, 23/Hct, and 16/Hct groups compared with the 44/Hct and 37/Hct groups; and both areas were less in the 9/Hct group compared with the other five groups (p < 0.05). For the hemisphere contralateral to occlusion, there was a direct correlation between hematocrit and oxygen delivery. However, for the hemisphere ipsilateral to occlusion, oxygen delivery increased as hematocrit decreased (44/Hct, 8.6 +/- 0.3 vs. 9/Hct, 13.6 +/- 0.4 [mean +/- SD, ml 100 g-1 min-1]). The results of this study support a hypothesis that hemodilution with DCLHb decreases the extent of focal cerebral ischemia.
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PMID:Focal cerebral ischemia in rats: effect of hemodilution with alpha-alpha cross-linked hemoglobin on CBF. 140 Jun 51

The stability properties of the iron(II)-dioxygen bond in myoglobin and hemoglobin are of particular importance, because both proteins are oxidized easily to the ferric met-form, which cannot be oxygenated and is therefore physiologically inactive. In this paper, we have formulated all the possible pathways leading to the oxidation of myoglobin to metmyoglobin with each required rate constant in 0.1 M buffer (pH 7.0) at 25 degrees C, and have set up six rate equations for the elementary processes going on in a simultaneous way. By using the Runge-Kutta method to solve these differential equations, the concentration progress curves were then displayed for all the reactive species involved. In this complex reaction, the primary event was the autoxidation of MbO2 to metMb with generation of the superoxide anion, this anion being converted immediately and almost completely into H2O2 by the spontaneous dismutation. Under air-saturated conditions (PO2 = 150 Torr), the H2O2 produced was decomposed mostly by the metMb resulting from the autoxidation of MbO2. At lower pressures of O2, however, H2O2 can act as the most potent oxidant of the deoxyMb, which increases with decreasing O2 pressures, so that there appeared a well defined maximum rate in the formation of metMb at approximately 5 Torr of oxygen. Such examinations with the aid of a computer provide us, for the first time, with a full picture of the oxidation reaction of myoglobin as a function of oxygen pressures. These results also seem to be of primary importance from a point of view of clinical biochemistry of the oxygen supply, as well as of pathophysiology of ischemia, in red muscles such as cardiac and skeletal muscle tissues.
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PMID:Hydrogen peroxide plays a key role in the oxidation reaction of myoglobin by molecular oxygen. A computer simulation. 142 Aug 96

A purine degradation study, thermography and near infrared spectroscopy of the extremities were performed on 2 young males with Fabry disease and 2 healthy controls. Two-minute semi-ischemic forearm exercise caused a distinct increase in lactate in all subjects, but venous hypoxanthine and ammonia were greatly increased only in the Fabry patients, suggesting a relatively hypoxic state of the extremities. Limb thermograms of the patients revealed glove and stocking type disturbance at rest. Poor recovery of the skin temperature of the hands and forearms after exercise was observed in the patients, but the sharp increase in oxygenated hemoglobin after total ischemia was found to be normal or near infrared spectroscopy. Neurotropin showed an analgesic effect, i.e. a strong and selective heat-productive action on the painful lesions, and suppressed the hypoxanthine level after exercise in 1 patient. Although the pathophysiology of the pain in Fabry disease has not been clearly elucidated, a relatively hypoxic state with peripheral hypothermia might play an important role in triggering of a painful attack or chronic burning paresthesia.
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PMID:Relative hypoxia of the extremities in Fabry disease. 145 89


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