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Biomedical subjects

M Beppu

Publications and source records attributed to M Beppu.

14 recordsLinked to original sources
PubMed1992

Antigenic determinants of senescent antigen of human erythrocytes are located in sialylated carbohydrate chains of Band 3 glycoprotein.

Naturally occurring IgG autoantibody against Band 3 glycoprotein of human erythrocyte membrane (anti-Band 3) recognizes the erythrocytes modified with oxidizing or SH-blocking agents as well as senescent erythrocytes. Location of the antigenic determinants of Band 3 this autoantibody recognizes was investigated by competitive inhibition studies of the antibody binding to the modified cells. Autologous IgG binds to the modified erythrocytes, and purified Band 3 totally inhibits the binding. This inhibitory activity of Band 3 was not affected by digestion of Band 3 with various proteases. Treatment of Band 3 with endo-beta-galactosidase that destroys the poly-N-acetyllactosaminyl sugar chain of Band 3 or with neuraminidase resulted in loss of the inhibitory activity. Oligosaccharides released from Band 3 by hydrazinolysis effectively inhibited the binding of autologous IgG and 125I-labeled purified anti-Band 3 to the modified cells, whereas the oligosaccharides depleted of acidic components did not. Endo-beta-galactosidase and neuraminidase destroyed the activity of the oligosaccharides, but alpha-L-fucosidase did not. Furthermore, human lactoferrin that contains sialylated two N-acetyllactosaminyl units also exhibited potent inhibitory activity, and the activity was destroyed by endo-beta-galactosidase and neuraminidase. These results indicate that the antigenic determinants of Band 3 are located in sialylated poly-N-acetyllactosaminyl sugar chains. Based on this finding, mechanism of appearance of the antigen on senescent erythrocytes recognized by anti-Band 3 (senescent antigen) was discussed.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1992

The osteocutaneous fibula flap: an anatomic study.

Recent studies related to the fibula flap have disagreed regarding the anatomy of the cutaneous branches of the peroneal artery. To clarify this issue, various dissections of 35 injected fresh cadaver legs were done. Identifiable skin branches were found in 23 of 25 dissections. Skin branches from the proximal third of the peroneal artery always travelled an intramuscular course. Skin branches from the distal two-thirds of the peroneal artery were usually affixed to the posterior crural septum. Legs with peroneal artery skin branches had from three to seven branches (average: 4.7); each branch contributed to the fibular periosteal blood supply. The most reliably found skin branch was located within 2 cm of the fibula midpoint. These findings reinforce the fact that a large skin island supplied by branches of the peroneal artery can be harvested with the fibula flap, and that the most reliable cutaneous vessels are found in the lower two-thirds of the leg, run posterior to the fibula in the posterior crural septum, and are always associated with muscular side branches.

Fibula↗
PubMed1992

Generation of senescent antigen on erythrocytes by partial blocking of SH groups of the membrane proteins.

Human erythrocytes treated with diamide (0.2 mM) or N-ethylmaleimide (0.1 mM) at 37 degrees C for 1 h were susceptible to binding of anti-band 3 immunoglobulin G autoantibody and hemoglobin. A definite degree of cell modification appeared to be required for the effective bindings since the cells treated with the reagents above these concentrations were less susceptible. The enhanced binding activities of the cells treated with diamide were abolished on treatment with dithiothreitol. Partial blocking of SH groups of the membrane proteins but not disulfide-mediated protein cross-linking may be essential for the formation of band 3 senescent antigen, which may not be a neo-antigen formed by chemical modification of band 3 but an antigen formed by topological alterations of the molecules in the membrane.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1979

Preparation of concanavalin A-ricin A-chain conjugate and its biologic activity against various cultured cells.

For the development of therapeutic agents that possess tissue-specific carriers, a method was devised to synthesize an artificial protein hybrid conjugate containing a moiety which binds to a cell membrane receptor and an active fragment of a toxic protein. By the introduction of an activated sulfhydryl group into concanavalin A (Con A), a conjugate of Con A and the ricin A-chain cross-linked with a disulfide linkage was synthesized. The purified conjugate was studied with regard to its inhibitory activity against protein synthesis in cell-free and cultured cell systems. The Con A-rich A-chain conjugate retained about one-third the inhibitory activity of ricin in a cell-free protein synthesis system. It also was highly toxic to cultured normal cells. These results indicate that the conjugate is a structural and functional analog of ricin and that the original membrane-binding chain (B-chain of ricin) could be replaced by Con A. Transformed cells were insensitive to this conjugate and required a longer preincubation time. The sensitivity of the normal cells was reduced in the presence of local anesthetics.

Animals↗
PubMed1979

Covalently cross-linked monovalent, divalent, and tetravalent derivatives of concanavalin A.

Dimeric succinyl-concanavalin A was cross-linked with ethylenediamine using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide a condensing agent. Thus, a divalent dimer and a tetravalent tetramer composed mostly of covalently cross-linked subunits bearing altered net charges were obtained. Photoaffinity labeling of the cross-linked dimer with p-azidophenyl alpha-D-mannopyranoside resulted in a specific label for its saccharide-binding site and yielded a nonvalent dimer and a monovalent dimer (showing no subunit exchange). However, hemagglutination and glycogen precipitation data suggested that the labeled binding site is shielded but not destroyed by the label and can still bind weakly an external saccharide ligand possibly due to unsteadiness of the shielding label. Although nonvalent and monovalent derivatives were mitogenic as well as divalent and tetravalent derivatives for mouse splenic lymphocytes, binding and stimulation experiments indicated that their stimulating efficiencies after binding to the cells were far lower than those of the multivalent counterparts. Their activities were inhibited by methyl alpha-D-mannopyranoside, suggesting that the weak activities of nonvalent and monovalent derivatives were due to the labeled sites entirely and partly, respectively. We suggest that the triggering of lymphocyte mitogenesis by concanavalin A may depend on cross-linkage of cell surface receptors.

Animals↗
PubMed1979

[An experimental study on the effects of the plating method for bone fractures--with reference to bone union and bone strength (author's transl)].

The plating method for bone fractures is in wide use. The author studied both new bone formation and bone atrophy of the cortex of fracture site after long periods of plating. This study is concerned with the bone strength of the fracture site as influenced by rigid plate fixation, and also with bone union after the removal of the plate. The experimental results, using mature rabbits as subjects, showed the following: X-rays of the bone union at the fracture site treated by the plating method confirmed evident union at 8 weeks after surgery. The bone strength at the region of this union, as tested by the bending method (an Instron Type Testing Machine was used), showed its highest values at 28 weeks after surgery. Yet, this was only 60% of the bone strength as measured at a non-fracture site; it then gradually declined in strength. On the other hand, in the case where the plate had been removed 8 weeks after surgery, bone strength was recovered to the same level as that of non-fracture sites 16 weeks after surgery. In conclusion, rigid plate fixation for a long period may result not only in progressive bone atrophy of the cortex but also in a delayed remodeling of the bone at the region of the bone union. It is, therefore, very important to remove the plate as early as possible once union has been achieved. Careful observation, however, is necessary during the short time between plate removal and the period when bone strength becomes again normal.

Animals↗
PubMed1976

Preparation of monovalent succinyl-concanavalin A and its mitogenic activity.

Monovalent succinyl-concanavalin A was prepared by photoaffinity labeling of succinyl-concanavalin A with p-azidophenyl a-D-mannopyranoside. This concanavalin A derivate showed a weak but definite mitogenic acitivity against mouse splenic lymphocytes and human peripheral lymphocytes, suggesting that direct receptor cross-linkage on the cell surface is not an obligatory prerequisite for the activation of lymphocytes.

Affinity Labels↗
PubMed1975

Photoaffinity labeling of concanavalin A. Preparation of a concanavalin A derivative with reduced valence.

Concanavalin A (Con A) was labeled with p-azidophenyl alpha-D-mannopyranoside under ultraviolet irradiation and the reaction products were separated by affinity chromatography on Sephadex G-100 at pH 5. One of the Con A derivatives thus obtained was characterized as a monovalent dimer at pH 5 and a divalent tetramer at pH 7 by sedimentation equilibrium and equilibrium dialysis, indicating that this photoaffinity labeling did not alter the quaternary structure of Con A. In agreement with these results, the labeled Con A did not show the capacity to precipitate glycogen at pH 5, but it formed precipitates with glycogen at pH 7. Although its hemagglutinating activity was found to be weaker than that of the native Con A, the dose-response cure of the labeled Con A in the mitogenic stimulation of human peripheral lymphocytes was almost identical to that of the native con A.

Affinity Labels↗