Methods have been developed for depositing thin stable semipermeable polymer membranes around aqueous microdroplets (mean diameter down to 5 μ or less) by either interfacial polymerization or interfacial coacervation. The enclosed aqueous phase may contain enzymes or other proteins, cell fragments, or intact cells. Examples of methods for preparing such microcapsules are given in detail, and some of their properties are described.
Platelet–surface interaction was studied using activated charcoal granules (AC), cellulose nitrate coated, activated charcoal granules (CAC), albumin – cellulose nitrate coated, activated charcoal granules (ACAC), and benzokonium – heparin – cellulose nitrate coated, activated charcoal granules (BHCAC). In studies where blood from dogs was recirculated through shunts, each containing 300 g of one of the above systems, it was found that both AC and CAC lowered the systemic blood platelet levels after 2 h of hemoperfusion. In hemoperfusion across these two systems, there was also an increase in the adhesiveness of platelets. In the case of ACAC and BHCAC, hemoperfusion for 2 h did not result in any significant decrease in the systemic blood platelet levels, nor was there an increase in the adhesiveness of platelets perfused across these two systems. Scanning electron microscopic studies were carried out with the CAC and ACAC systems before and after contact with blood. There was marked platelet and fibrin deposition and entrapment of formed elements of blood in the case of the CAC. In the case of the ACAC there was no platelet adhesion, fibrin deposition, or entrapment of formed elements of blood. This study has led to the use of the ACAC microcapsule artificial kidney in the treatment of patients with chronic renal failure and acute intoxication.
Galactosamine-induced fulminant hepatic failure rats have been used as a model for statistical assessment of liver support systems. The present study reports in detail the biochemical, hematological and histological changes in these animals. They have been used to study statistically the effects of ACAC charcoal hemoperfusion, cross-circulation and liver perfusion on long-term survival in fulminant hepatic failure.
In this study, we prepared PolyHb-SOD-catalase (intermolecularly cross-linked hemoglobin, superoxide dismutase (SOD), and catalase). We found that PolyHb-SOD-catalase is effective in scavenging oxygen-derived free radicals. In the xanthine/xanthine oxidase system, the initial rate of cytochrome c reduction was 2.13 +/- 0.26 nmoles cyt. c/min for PolyHb alone. PolyHb- SOD-catalase reduced this to 0.56 +/- 0.08 nmoles cyt. c/min because of its ability to eliminate superoxide (O2-). Addition of PolyHb to 200 microM of hydrogen peroxide (H2O2), changed the H2O2 level slightly to 192 +/- 0.4 microM. Addition of PolyHb-SOD-catalase, on the other hand, lower the level to 41 +/- 0.3 microM. Results also show that both effects were dependent on the concentration of SOD-catalase cross-linked with hemoglobin. Oxidative challenge with H2O2 resulted in minimal changes in the absorbance spectra of PolyHb-SOD-catalase. With PolyHb, there were spectral changes reflecting the formation of methemoglobin and heme degradation. Furthermore, the amount of iron released, after incubation with 250 microM H2O2, was 6.8 +/- 1.8 micrograms/dl for PolyHb-SOD-catalase and 76.6 +/- 1.0 micrograms/dl for PolyHb. These results show that cross-linked SOD-catalase prevents oxidative reactions involving the hemoglobin component of PolyHb-SOD-catalase.
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