Biomedical subjects
Publications and source records attributed to B Ecanow.
Hemoglobin dissolved in a coacervate system shows the properties of a resuscitation fluid. In the coacervate system used, the equilibrium phase was the colloid rich phase. We propose a new definition of the coacervate phase to be that phase in a coacervate system which is most dissimilar to water in its physical chemical properties.
The conductivity of three xanthines (caffeine, theobromine, and theophylline) and three sugars (glucose, sucrose, and glucose-6-phosphate) was measured as part of a docusate coacervate system. The conductivity of the coacervate phase was always lower than the equilibrium phase. Conductivity of xanthines showed that caffeine had the highest conductivity, followed by theobromine and theophylline. At high concentrations, these values fell and the highest conductivity was seen in samples containing theobromine, caffeine, and theophylline. For sugars at high concentrations, the lowest values of conductivity were seen in sucrose samples. Saturated theophylline samples exhibited an increased volume in the coacervate phase volume. These findings are discussed with reference to various clinical parallels and thus supply evidence that coacervates can provide a useful model for human cytoplasm.
The electrical conductivity effects of dispersed, coagulated, and flocculated systems were investigated using sulfamerazine powder, an insoluble, hydrophobic drug to prepare the suspension systems. For the dispersed systems, a peak in conductivity was observed at a drug concentration between 5 and 15%. The critical coagulating concentration was defined as the concentration of drug at which a maximum in specific conductance was observed. At this concentration, a maximum number of charged particles were in the system. Coagulated suspensions showed higher conductance values than the dispersed systems at equivalent concentrations; however, the critical coagulating concentration value appeared to be the same. For flocculated suspensions there was an increase in conductance with drug concentration with no perceptible peak conductance value.
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The significant occurrence of thrombophlebitis in patients administered diazepam intravenously was described recently. This side effect has been attributed to the crystallization of diazepam and its subsequent precipitation upon contact with blood or intravenous fluids. The current study was designed to reveal whether the solubilizing capability of poloxamer 188 reduces the incidence of thrombotic and inflammatory effects of diazepam in rabbits. The incidence of early (3-hr) ear vein necrosis was 72% in the diazepam-treated ears, while the incidence of necrosis in the ears that received poloxamer 188 as a vehicle for diazepam was 25%. The occurrence of thrombosis and loss of vessel integrity also was higher in diazepam-treated ears than in those treated with diazepam plus poloxamer 188. Solubilization of diazepam with poloxamer 188 may decrease the incidence of the tested side effects.
Sodium salicylate was microencapsulated with ethylcellulose 100 cp by polymer deposition from cyclohexane by temperature change to give a finer product, with slower drug release, than that obtained with 10 cp grade of ethylcellulose. Scanning electron microscope and polymer disc swelling studies confirmed that larger microcapsules after drug release ruptured into smaller particles with swollen surfaces containing pores. Treatment of microcapsules with paraffin wax solution retarded release of core material, the release being affected by the percentage of sealant used and the particle size of the product. The mechanism of release from the sealed microcapsules was complex involving mainly diffusion, but polymer erosion and drug binding were also involved. Other sealant materials were less effective in retarding dissolution.
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Controlled cellular growth exists in an aqueous matrix that undergoes a spectrum of reversible solvent and structural conformational changes. In contrast, malignant tumor formation occurs in an irreversible nonpolar aqueous matrix (coacervate); that is, in a physicochemical sense uncontrollable cell growth exists in a hydrocarbon-like milieu. It is proposed that foreign isoluble particles which locate on cellular surfaces can induce such coacervate structuring. Resultant formation of abnormal film matrices could initiate pathological transformations in the morphology, metabolism, and replication of the affected cells. In short, this abnormal matrix formation may be a critical factor in the development of malignancies, both avascular and vascular stages. It would follow that drugs or other agents capable of disrupting coacervated water matrices could be effective in the treatment of cancer. Experimental studies in our laboratory and clinical data from other sources support this hypothesis.
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