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Query: UMLS:C0917798 (cerebral ischemia)
 17,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Perfluorochemical liquids (PFC's) are good solvents for gases and as such, have significant relevance to the field of biology. Approximately 40 ml of oxygen will dissolve in 100 ml of most PFC's, and carbon dioxide is at least twice as soluble. This makes these compounds attractive as vehicles for these and other gases in-vivo and in-vitro. Although many have low viscosities and surface tensions, it is necessary to emulsify them for intravenous use and organ perfusion. The emulsion particles must be very fine, usually about 150 nanometers in diameter, and stable in the presence of blood and other biological fluids. Presently the two most used emulsifying agents are Pluronic F68 and phospholipids. Emulsions made with the former are now known to cause complement activation with accompanying transient decreases in circulating leukocytes and oxygen tension. This phenomenon is reversible and usually not severe. Phospholipid-stabilized PFC emulsions do not activate complement and should therefore, be advantageous. Areas of current research utilizing PFC emulsions are in tumor therapy, by increasing the oxygenation of otherwise hypoxic cells, in ischemic heart treatment, and in alleviating the effects of cerebral ischemia. Many other applications of PFC's are being pursued, and even more research activity in this field is likely.
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PMID:Perfluorochemicals as oxygen transport vehicles. 305 41

Perfluorocarbon blood substitutes have been shown to exert a protective effect in animal models of cerebral ischemia. The mechanisms by which PFCs improve cerebral hemodynamics are uncertain, however decreased viscosity, small particle size and high oxygen solubility relative to plasma are important factors. Extensive perfluorocarbon exchange transfusion (FC-43) in the rat to a hematocrit of 1%, produces a 100% increase in total cerebral blood flow (FIO2 = 1.0, CaO2 = 6 vol%). Similar increases were seen in normal blood circulated animals breathing 12% O2 (CaO2 = 12 vol%). Therefore, immediately following PFC exchange and the resulting decrease in CaO2, oxygen delivery to the brain is maintained by increasing total blood flow in a manner similar to hypoxic hypoxia.
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PMID:Regional cerebral blood flow in normal blood circulated and perfluorocarbon transfused rats. 379 51

We have previously reported that the combined administration of mannitol and perfluorochemical blood substitutes is evidently effective in protecting the brain from cerebral ischemia. This experimental study was designed to develop more effective method in suppressing brain infarction than the combined treatment of mannitol and PFC. Using the "Canine model of complete ischemic brain regulated with a perfusion method" in which it is possible to control the degree of blood flow to a cerebral hemisphere via a perfusion pump, the effect of eight agents including six kinds as the free radical scavenger on cerebral ischemia was investigated. Eight agents were mannitol, vitamin E (Vit. E), dimethyl sulfoxide (DMSO), vitamin C, glycerol, nizofenone (Y-9179), dexamethasone (Dexa.) and suloctidil (MY-103). After pretreatment with each agent, blood flow was reduced via the pump to 1/10 of the normal state and 1 hour later, return to the normal state was allowed. Subsequent changes in EEG were observed and the effects of the drugs evaluated. In the control group, no recovery of electrical activity was seen, but in six groups among eight treated groups, i.e., treated with mannitol, Vit. E, DMSO, MY-103, Y-9179 and Dexa, gradual emergence of slow waves was observed. And more favorable effects were found when the combined administration of mannitol, Vit. E and Dexa was made in the same experimental schedule as compared with the single administration of each of these drugs. Furthermore in the animals administered with PFC in combination with mannitol, Vit. E and Dexa, flattening of electrical activity could not be seen throughout the period of severe ischemia. Moreover, the power of electrical activity recovered nearly to the preischemic state immediately after recirculation. Although the possible mechanisms are not yet completely clarified, the present results are thought to indicate that this new combination therapy utilizing PFC with mannitol, Vit. E and Dexa may be useful in the treatment of cerebral ischemia.
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PMID:[Experimental study of cerebral protective effect on cerebral ischemia of various antioxidants and other agents. With special reference to the combined treatment of mannitol, vitamin E, dexamethasone and perfluorochemicals]. 632 77

Using the "canine model of complete ischemic brain regulated with a perfusion method" in which it is possible to control the degree of blood flow to a cerebral hemisphere via a perfusion pump, the effects of mannitol (which acts as a free radical scavenger) and perfluorochemical emulsion (PFC, which has 0.1 micrograms of average particle size and a high oxygen-carrying capacity) on cerebral ischemia were investigated. After pretreatment with the drugs, blood flow was reduced via the pump to 1/10 of the normal flow volume and 1 hour later, return to a normal flow was allowed. Subsequent changes in electrical activity were observed and the effects of the drugs evaluated. In the control group, no recovery of electrical activity was seen, but in the animals treated with either mannitol or PFC, incomplete, yet distinct recovery was apparent. In the animals administered with mannitol together with PFC, however, marked recovery was evident. These experimental results indicated that a combined administration of PFC and mannitol is effective in protecting the brain from cerebral ischemia.
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PMID:[Combined use of mannitol and perfluorochemicals in experimental cerebral ischemia]. 641 97