Kenji Honda

The components contained in polyethylene glycol of commercial grade (PEG-6,000) as cell fusogen

Summary By reprecipitation with ether and/or by dialysis in water completely disappeared the fusion activity of PEG-6,000 in commercial grade with keeping the whole activity of cell aggregation. It was concluded that PEG-6,000 in commercial grade contains at least two components, one of which has the activity of cell aggregation and the other of which has the activity of perturbation of phospholipid bilayer. The former is PEG-6,000 itself and the latter is considered to be a catalyst or terminator of polymerization of ethylene oxide and/or an antioxidant for PEG.

Prevention of Leakage of Di-(2-ethylhexyl)phthalate from Blood Bags by Glow Discharge Treatment and Its Effect on Aggregability of Stored Platelets

Abstract. Platelets storage in glow discharge treated PVC bags was studied. The amount of leaked di‐(2‐ethylhexyl) phthalate (DEHP) was 150–200 μg/ml/day in the nontreated PVC bags, but only 20–40 μg/ml in the treated bags after 48 h. The adhesion of silicone to PVC was much improved, and consequently, uniform coating with silicone became feasible. The decrease of the ability of platelets to aggregate was accelerated by DEHP. When stored platelets were resuspended in fresh plasma, the ability to aggregate was gradually restored. However, the degree of restoration of the ability of platelets which had been incubated with DEHP was low. When platelets were stored in the glow discharge treated and then silicone‐coated PVC bags, their adhesion on the surface and the decrease of their function were prevented.

Activities of cell fusion and lysis of the hybrid type of chemical fusogens (I) structure and function of the promotor of cell fusion

Summary Monomeric lipids, for example, oleic acid, stearic acid, lauric acid, oleyl alcohol and p-isooctyl phenol, were introduced through ester or ether bonds to oligoethylene glycol with various molecular weights. The activities of hemolysis and fusion of these oligomeric lipids were examined using human erythrocytes in the presence or absence of high molecular weight of water-soluble polymers such as polyethylene glycol (Mw=6,000) or dextran (Mw=70,000). When the chain length of polyoxyethylene of the oligomeric lipids was less than 20, the activities of hemolysis and fusion were both enhanced. On the other hand, when the chain length was more than 20, the two activities were reduced to a different degree for each other.

Fluorescence polarization study on the increase of membrane fluidity of human erythrocyte ghosts induced by synthetic water-soluble polymers

The effect of water-soluble polymers on the membrane fluidity of human erythrocyte ghosts was investigated and was compared with that of concanavalin A by means of the fluorescence polarization technique. 8-Anilino-1-naphthalene sulfonic acid sodium salt and 1,6-diphenyl-1,3,5-hexatriene were used as probe molecules. The membrane fluidity was increased by the addition of polycations with concentrations of less than 2 x 10(-3) wt% 60 min after mixing. The fluidity changes were affected by the chemical structure (hydrophobicity, charge density, etc.) of polycations. Thus, the membrane fluidity increased markedly with increasing charge density on the chain backbone of polycations. On the other hand, nonionic polymers such as poly(ethylene glycol) and poly(N-vinyl-2-pyrrolidone) changed the membrane fluidity in a biphasic manner. That is, the fluidity of human erythrocyte ghost was temporarily increased and then decrease. For example, 20 wt.% of poly(ethylene glycol) gave a maximum fluidity 15 min after mixing with erythrocyte ghosts. A similar fluidity change was observed by adding concanavalin A. Such fluidity changes were not observed when lipid bilayer vesicles were used instead of cell membranes. These results suggested that the increase of membrane fluidity resulted from the intramembraneous aggregation of membrane-bound proteins which was induced by the added polymers. Cell agglutination was also induced by the addition of a large amount of polymers. This agglutination was considered to be due to the intermembraneous aggregation of membrane-bound proteins.

Interaction of human erythrocyte ghosts or liposomes with polyethylene glycol detected by fluorescence polarization

Abstract The membrane fluidity of human erythrocyte ghost was temporarily increased by the addition of polyethylene glycol with molecular weight of 7500. On the other hand, the fluidity of dipalmitoylphosphatidyl choline bilayer liposomes was monotonously decreased by the addition of polyethylene glycol. Fusion of liposomes was inhibited by the interaction with polyethylene glycol. The temporary increase in membrane fluidity of erythrocyte ghosts was considered to be the result of the clustering of membrane-bound proteins which is believed to be one of the most important sequences in cell fusion.

Changes in 2,3-DPG Content and Oxygen Affinity in Erythrocytes Stored at 4°C

Abstract. The 2,3‐DPG content of red blood cells increased within the first 24 h when fresh erythrocytes or whole blood were stored at 4°C. This phenomenon was strongly pH dependent. The temporary increase in 2,3‐DPG was scarcely observed below pH 7.4 or above pH 7.8. In the case of whole blood, the increase was observed in CPD blood but not in ACD blood. Similar results were obtained with erythrocytes suspended in saline, when its pH was adjusted to approximately 7.6. Plasma proteins were not essential for the increase in 2,3‐DPG content. Extracellular oxygen levels were continually measured in erythrocyte suspensions in order to check the changes in oxygen affinity of hemoglobin without damaging the cells. Both extracellular oxygen levels and 2,3‐DPG contents were simultaneously increased by keeping fresh erythrocytes at 4°C. Inhibition of glycolysis with sodium fluoride and monoiodoacetic acid indicated that the in vivo steady state of glycolysis in erythrocytes might be altered by chilling to make the rate of 2,3‐DPG synthesis faster than that of 2,3‐DPG decomposition.

Change of Oxygen Affinity of Hemoglobin in Different Conditions of Blood Preservation

Abstract. Changes of oxygen affinity of hemoglobin were studied in blood preserved in different conditions. Changes in hemoglobin function were least in CPD blood in plastic bags, and more extensive in ACD blood in plastic bags, ACD packed red blood cells in plastic bags and ACD blood in glass bottles, respectively. These decreases are consistent with the changes of organic phosphates levels during storage found in earlier studies. When old erythrocytes were incubated with inosine, pyruvate and phosphate, defective oxygen transport function was completely restored even after 7 weeks storage in ACD.

Interaction between Heme Bonded to Polyvinylpyridine or Polyvinylimidazole and Molecular Oxygen

Iron-protoporphyrin chloride was allowed to bond to such a polymeric derivative as poly-4- vinylpyridine (PVP) or poly-1-vinyl-2-methylimidazole (PVMI) in various solvents and the interaction between the above hemochrome and molecular oxygen (O2) was examined in com- parison with the analogous monomeric complexes.The equilibrium constants in the complexation between heme (Fe2+) and the following axial ligands are as follows: pyridine; 51.3 (//mol), imidazole; 45.5 (l/mol), PVP; 1.14 X 1O2 (l/mol), PVMI; 2.55 x 108 (l/mol). This result indicates that a polymeric hemochrome is more stable than a monomeric one.It is known that a central iron ( II ) ion is immediately oxidized, when a Fe ( II ) protoporphyrin complex is exposed to O2 in an aqueous solution. However, since the oxidation of the polymeric complex retarded under an appropriate condition, the stable oxygen complex formed and then the reversible oxygenation could occur. In addition, the oxygenation rate of the polymeric complex was higher than that of the monomeric complex and the degree of saturation of oxygen of the polymeric complex was approximately 100%.