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J Sunamoto

Publications and source records attributed to J Sunamoto.

54 records · Page 3Linked to original sources
PubMed1985

Liposomal membranes. XX. Autoxidation of unsaturated fatty acids in liposomal membranes.

Autoxidation of egg phosphatidylcholines and polyunsaturated fatty acids, arachidonic and linoleic acids, has been investigated in homogeneous and liposomal membrane systems. In order to monitor the very initial stage of the radical chain mechanism of the autoxidation, an improved method using 1,1-diphenyl-2-picrylhydrazyl radical was newly implemented and used with the regular thiobarbituric acid test to determine the peroxides of polyunsaturated fatty acids. Autoxidation of polyunsaturated fatty acids or lipids was significantly enhanced in liposomal bilayers compared to that in a bulk homogeneous solution. In liposomal bilayers, the reaction could be controlled by membrane fluidity, which was confirmed by the fluorescence polarization technique using 1,6-diphenylhexatriene and dansylhexadecylamine. Even vitamin E esters such as the acetate and the pivalate could depress effectively the autoxidation of egg phosphatidylcholines in bilayer systems, which supported Lucy's proposal (Diplock, A.T. and Lucy, J.A. (1973) FEBS Lett. 29, 205-210) about the importance of the side-chain of vitamin E as an antioxidant.

Animals↗
PubMed1984

Increased lung uptake of liposomes coated with polysaccharides.

Liposomes labeled with [14C]coenzyme Q10 in the lipid bilayer were coated with various polysaccharide derivatives, i.e., palmitoyl conjugates of pullulan, pullulan phosphate, amylopectin, amylopectin phosphate and amylopectin sulfate. The kinetics of disposition and the tissue distribution of [14C]coenzyme Q10 after intravenous injection of the liposomes into guinea pigs were investigated. Lung uptake of radioactivity after injection of the O-palmitoyl amylopectin- and O-palmitoyl amylopectin phosphate-coated liposomes was 5- and 3-times higher, respectively, at 30 min after injection than that of the conventional liposomes. For doubly labeled liposomes with [3H]inulin and [14C]coenzyme Q10, the 3H/14C ratios in the lung, spleen and heart were similar to one another. Urinary excretion of [3H]inulin encapsulated in O-palmitoyl amylopectin-coated liposomes was much lower than that of unencapsulated [3H]inulin. These observations suggest that the O-palmitoyl amylopectin-coated liposomes are rather stable in vivo and are taken up into tissues in the intact form.

Animals↗
PubMed1984

Importance of methionine residues in the enzymatic carboxylation of biotin-containing peptides representing the local biotinyl site of E. coli acetyl-CoA carboxylase.

A biotin-containing hexapeptide Ac-Glu-Ala-Met-Bct-Met-Met (1) that represents the local biotin-containing site of Escherichia coli acetyl-CoA carboxylase has been prepared by the solid phase method. Peptide 1 is carboxylated by the biotin carboxylase subunit dimer of E. coli acetyl-CoA carboxylase with the following kinetic parameters; Km 12 mM, Vmax 2.8 microM X min-1. These compare with the parameters for biotin of Km 214 mM and Vmax 28 microM X min -1. Hence, the overall reactivity (Vmax/Km) of 1 is 1.8 times greater than that of free biotin. When all methionines in 1 are replaced by alanine, the resulting peptide (2) retains a similar binding ability but with a much decreased Vmax. It was also found that peptide 3, which carries an N epsilon-benzyloxycarbonyllysine in place of biocytin in 1, decreases the Km of biotin threefold.

Acetyl-CoA Carboxylase↗
PubMed1983

Liposomal membranes. XIV. Fusion of liposomal membranes induced by polyisoprenoids as monitored by fluorescence quenching method.

Fusion of the single-walled liposomes of egg phosphatidylcholine as induced by the polyisoprenoids such as solanesol, trans-ethyl decaprenoate (EDP), coenzyme Q10, and dolichol has been investigated adopting the fluorescence quenching method. Relative efficiency of the polyisoprenoids employed on the induced fusion of liposomes was a sequence of solanesol less than or equal to EDP much less than CoQ10, dolichol, which was consistent with the result previously obtained by the dye-release method.

Cell Fusion↗
PubMed1982

Liposomal membranes. XI. A suggestion to structural characteristics of acido-thermophilic bacterial membranes.

To understand the role of omega-cyclohexyl fatty acid residue of lipids in acido-thermophilic bacterial membranes, three unusual phosphatidylcholines, 1, 2-di-11-cyclohexylundecanoyl-L-alpha-phosphatidylcholine (11CYPC), 1,2-di-13-cyclohexyltridecanoyl-L-alpha-phosphatidylcholine (13CYPc), and 1-13-cyclohexyltridecanoyl-2-11-cyclohexylundecanoyl-L-alpha- phosphatidylcholine (1-13CY-2-11CYPC) were prepared and the steady-state fluorescence anisotropy of 1, 6-diphenylhexatriene (DPH) in the hydrophobic domain of these liposomal bilayers was determined. Compared with the case of dipalmitoyl (DPPC) or dimyristoyl phosphatidylcholine (DMPC), introducing the omega-cyclohexyl moiety onto lecithins makes the bilayers fluid below the phase transition temperature, while immobilizes them above the phase transition temperatures. The properties of the unusual phosphatidylcholine liposomes suggested by the steady-state fluorescence anisotropy investigation were in good agreement with those obtained from the thermotropic and permeability investigations. Results obtained are discussed from the view point of the role and function of lipid membranes of acido-thermophilic bacteria which contain unusual fatty acids.

Bacillus↗
PubMed1982

Liposomal membranes. XII. Adsorption of polysaccharides on liposomal membranes as monitored by fluorescence depolarization.

Under specific conditions where neither induced aggregation nor fusion is brought about, the adsorption of polysaccharides on liposomal membranes was investigated by the fluorescence depolarization technique using fluoresceinylthiocarbamoyl-dextrans (FITC-dex) as probes. The adsorption of FITC-dex on liposomes significantly increased the fluorescence polarization of FITC fluorophore due to the restriction of the mobility of the dextrans. Dextran with larger molecular weight was efficiently adsorbed on liposomes, in good agreement with the tendency for polysaccharide-induced aggregation of liposomes (Sunamoto et al. (1980) J. Biochem. 88, 1219--1226). The adsorption seemed to be related to the fluidity of liposomal membranes, since dextrans were adsorbed more efficiently on egg lecithin liposomes than dipalmitoyl lecithin liposomes at 25.0 degrees C. However, the adsorption of dextrans did not cause a significant change in the fluidity of the liposomal membrane itself under the specific conditions adopted in this work; this was ascertained from the mobility of sodium 8-anilino-1-naphthalenesulfonate (ANS) intercalated close to the surface of liposomes.

Chemical Phenomena↗
PubMed1980

Liposomal membranes. VI. Polysaccharide-induced aggregation of multilamellar liposomes of egg lecithin.

Induced aggregation of multilamellar liposomes of egg lecithin with several polysaccharides, such as pullulan, dextran, hydroxyethylstarch, and amylopectin, has been investigated in conjunction with structural characteristics of polysaccharides, incubation temperature, ionic strength, and surface charge of liposomes. Aggregation of liposomes as a function of time was followed by monitoring turbidity of the liposome suspension at 600 nm. The inverse relationship between the minimal concentration and molecular weight of polysaccharides for the induced aggregation of liposomes was observed for all the polysaccharides employed. Polysaccharides having larger excluded volume more easily bind to liposomes, leading to the acceleration of the aggregation of liposomes. Hence, the order of efficiency of polysaccharides for the promotion of liposome aggregation was pullulan greater than dextran greater than hydroxyethylstarch congruent to amylopectin. Increasing the surface charge of liposomes brought about a decrease in aggregation irrespective of the sign. Even when negatively charged liposomes were incubated with the cationic DEAE-dextran, the liposome aggregation was depressed. These results including salt effect and temperature dependency of the induced aggregation of liposomes supported a plausible mechanism for the reaction, the polysaccharide-bridging mechanism, which has been provided for the polysaccharide-promoted agglutination of human erythrocytes.

Chemical Phenomena↗
PubMed1978

Liposomal membrane. I. Chemical damage of liposomal membranes with functional detergent.

The interaction and reaction between liposomal membrane and a functional detergent, N-hexadecyl-N-(imidazol-4-yl)methyl-N,N-dimethylammonium chloride hydroperchlorate (Im-I), have been investigated in conjunction with the leakage of bromothymol blue encapsulated as a marker in the bilayers of liposomes. Im-I carries an imidazole moiety and was expected to behave as a simple lipase model. The reaction with Im-I significantly enhanced the leakage of bromothymol blue encapsulated in the egg lecithin and dipalmitoyl phosphatidylcholine liposomes. During the course of reaction with Im-I, the formation of acyl-imidazole intermediate was clearly identified, which was certainly connected with the bromothymol blue release. From various kinetic results on bromothymol blue release and acyl-imidazole formation, it has been suggested that the bromothymol blue release from liposomal bilayer may be caused by the local and instantaneous decomposition of lipids when Im-I penetrates into the bilayer. However, it has also been demonstrated that the immediate reconstruction of liposomes retains the barrier function to protect against the further release of bromothymol blue.

Biological Transport↗
PubMedDate not supplied

Molecular chaperone-like activity of hydrogel nanoparticles of hydrophobized pullulan: thermal stabilization with refolding of carbonic anhydrase B.

We have been studying the formation of hydrogel nanoparticles by the self-aggregation of hydrophobized polysaccharide and the effective complexation between these nanoparticles as a host and various globular soluble proteins as a guest. This paper describes a new finding that refolding of the heat-denatured enzyme effectively occurs with the nanoparticles and beta-cyclodextrin according to a mechanism similar to that of a molecular chaperone. In particular, the irreversible aggregation of carbonic anhydrase B (CAB) upon heating was completely prevented by complexation between the heat-denatured enzyme and hydrogel nanoparticles formed by the self-aggregation of cholesteryl group-bearing pullulan (CHP). The complexed CAB was released by dissociation of the self-aggregate upon the addition of beta-cyclodextrin. The released CAB refolded to the native form, and almost 100% recovery of the activity was achieved. The thermal stability of CAB was drastically improved by capture of the unfolded form which was then released to undergo refolding.

Carbonic Anhydrases↗
PubMedDate not supplied

Direct extraction of A and B blood group antigens from human red cells by liposomes.

BACKGROUND: Some of the major blood group antigens are on lipids and proteins of the red cell membrane. Incubation of intact red cells with liposomes containing specially designed artificial lipids has been shown to result in the extraction of membrane proteins by the liposomes. The extraction of blood group structures and the retention of their antigenicity have not been reported. STUDY DESIGN AND METHODS: After the incubation of red cells with liposomes, the extraction of the antigens from human red cells by liposomes was examined by evaluation of the agglutination of the liposomes by respective antisera. RESULTS: Agglutination specific to the A and B blood group antigens was seen, which indicated that the antigenicity of the blood group antigens was retained even after the extraction by the liposomes. The presence of an artificial boundary lipid, 1,2-dimyristamido-1,2-deoxyphosphatidylcholine, in the liposome was crucial to the efficient extraction of the A and B antigens. On the other hand, the extraction of D, M, N, and P1 was not always detectable by agglutination. CONCLUSION: The A and B blood group antigens were directly extracted from red cells by liposomes without loss of antigenicity.

ABO Blood-Group System↗
PubMedDate not supplied

Utility of liposomes coated with polysaccharide bearing 1-amino-lactose as targeting chemotherapy for AH66 hepatoma cells.

The cell recognition element is very important for drug delivery systems. We synthesized cholesteryl pullulan (CHP) bearing 1-aminolactose (1-AL) and introduced a saccharide, cholesteryl pullulan bearing 1-aminolactose (1-AL/CHP), to an outer layer of the conventional liposome as a cell recognition element. Lectin recognized the beta-galactose by aggregation of 1-AL/CHP coated liposome (1-AL/CHP liposome). The uptake of this liposome to AH66 rat hepatoma cells was greater than in liposomes without 1-aminolactose in vitro. Furthermore, 1-AL/CHP liposomal adriamycin showed a stronger antitumor effect in comparison with other types of liposomal adriamycin in vitro. When in vivo tumor-targeting efficacy was investigated in AH66 tumor transplanted mice using 3H-liposome, the tumor/serum radioactivity ratio in mice injected with 1-AL/CHP liposome was higher than that of mice injected with other liposomes. These observations suggest that 1-AL is effective as a cell recognition element. As a result, 1-AL/CHP liposome is considered to be a good carrier of anticancer drugs for the active targeting of tumor cells.

Animals↗
PubMedDate not supplied

Selective uptake by cancer cells of liposomes coated with polysaccharides bearing 1-aminolactose.

We investigated the selective uptake of liposomes chemically modified by polysaccharides-cholesterol derivatives with 1-aminolactose (lactose) in two human hepatoma cell lines (HUH7 and Alexander), a human colon cancer cell line (FCC) and a human lung cancer cell line (KNS). The uptakes of the labeled liposomes alone (conventional liposomes), those with cholesterol pullulan (CHP) and with lactose (lactose CHP) were compared in four cancer cells and normal rat hepatocytes after 3 hours of incubation. The radioactivities of the lactose CHP were 4.4, 4, 3.4 and 4.4 times greater than those of CHP in HuH7, Alexander, FCC and KNS cells, respectively, after 3 hours of incubation. All the above differences were statistically significant (p < 0.01). No statistically significant differences were seen in the case of hepatocytes. Thus, cancer cells have a common affinity with lactose CHP liposomes, however, these mechanisms appear to have no connection with the galactose-specific asialoglycoprotein receptors of hepatocytes.

Animals↗
PubMedDate not supplied

Antitumor effect of polysaccharide coated liposomal adriamycin on AH66 hepatoma in nude mice.

Drug delivery systems play a crucial role in cancer chemotherapy, not only in the achievement of sufficient tumoricidal effect but also in minimizing systemic side effects. We investigated the effect of liposomal adriamycin with tumor recognition molecule, 1-aminolactose (1-AL), on AH66 hepatoma transplanted into nude mice. Adriamycin (ADM) was encapsulated in liposome coating with cholesterol pullulan (CHP) to increase the stability in the blood stream. 1-AL was assembled to the outer layer of CHP-coated liposomal ADM as a tumor recognition molecule. In an in vivo therapeutic study. 1-AL/CHP-coated liposomal ADM restrained tumor growth more when compared with CHP-coated liposomal ADM. Thus, 1-AL/CHP-coated liposome seems to be a carrier of ADM to tumor cells.

Animals↗