Takeshi Kitao

Inhibition of erythrocyte ATPase activity by aclacinomycin and reverse effects of ascorbate on ATPase activity

We studied the effect of aclacinomycin on human erythrocyte membrane enzymes. Aclacinomycin inhibited ATPase, including Na−K-dependent ATPase, ouabain insensitive ATPase and Ca-ATPase. However acetylcholinesterase was not inhibited by aclacinomycin. The ATPase activities were not inhibited by aclacinomycin if ascorbate was added to the incubation mixture. However other reducing agents, α-tocopherol, superoxide dismutase and catalase had no effect on ATPase activity. Ascorbate may protect membrane proteins and lipids from peroxidate damage.

Agglutination of leukemic cells and daunomycin entrapped erythrocytes with lectin in vitro and in vivo

Wheat germ agglutinin (WGA) agglutinated the L1210 leukemic cells and daunomycin entrapped erythrocytes in vitro. Comparing with control preparations, the greatest increase in survival was obtained in vivo when the daunomycin entrapped erythrocytes and WGA were given to BDF1 mice bearing L1210 cells.

Species difference in the effects of proteolytic enzymes on red cell membrane.

Pronase and α-chymotrypsin digested the major glycoprotein in the human and mouse red cell membranes and in SDS gel electrophoresis the glycoprotein disappeared accompanied by the appearance of a new band of lower mol.wt. However in the membranes of sheep, rat and rabbit, no digestion was demonstrated. The effects of pronase on anion permeability were almost identical for human and animal erythrocytes.

Monoclonal antibodies to L-asparaginase

Five hybridomas secreting monoclonal antibody toE. coli L-asparaginase were isolated. These monoclonal antibodies were classified into 3 different subclasses; Ig G1 (1 clone), Ig G2 (2 clones) and Ig G3 (2 clones). One of them possessed anti-L-asparaginase neutralizing activity. Four antibodies examined demonstrated a linear Langmuir binding plot and binding affinities, with equilibrium dissociation constant (Kd) ranging between 2.5×10−9M and 6.3×10−10 M. The monoclonal antibodies should be useful probes for investigation of the enzyme activity.

Purification of pig kidney diamine oxidase (histaminase) and in vivo effects on passive cutaneous anaphylaxis and histamine induced bronchoconstriction of guinea-pigs

Histaminase (diamine oxidase) was purified from pig kidney using cadaverine-Sepharose affinity chromatography. Pretreatment of guinea-pigs with histaminase caused marked inhibition of the passive cutaneous anaphylaxis. The effect of histaminase on histamine induced bronchoconstriction in vivo was studied. Histaminase significantly reduced the response in guinea-pigs. Histaminase is effective as a potent antihistaminic agent in vivo.

Rosette formation of tumor cells with concanavalin A treated erythrocytes.

Trypsinized human erythrocytes were incubated with concanavalin A at 4°C. After removal of free concanavalin A, the erythrocytes were incubated with Ehrlich ascites tumor cells at 37°C. The erythrocytes formed rosettes with the tumor cells.

G6PD Kanazawa: A New Variant of Glucose-6-Phosphate Dehydrogenase Associated with Congenital Nonspherocytic Hemolytic Anemia

A new variant of G6PD associated with chronic nonspherocytic hemolytic anemia (CNSHA) in a Japanese male is described. This variant is unique in that it has a normal electrophoretic mobility, normal Km for glucose-6-phosphate and NADP, and a normal utilization of the substrate 2-deoxyglucose-6-phosphate and deamino-NADP. It also shows a decreased thermal stability and a biphasic pH curve. These characteristics distinguish this variant from previously reported variants associated with CNSHA and we have called it G6PD Kanazawa.

Deoxyribonuclease immobilized on the erythrocytes

Bovine pancreatic deoxyribonuclease (DNase I) was immobilized on human erythrocytes with several procedures. DNase immobilized on the erythrocytes by chromic chloride showed DNase activity in vitro. Other binding procedures inhibit the immobilized DNase activity.

[Meningeal leukemia--report of an adult case].

Meningeal leukemiaは白血病の緩解中におこりやすく,その発生機転は非常に興味ある問題を含んでいる. meningeal leukemiaは小児用白血病に多く発症するが,成人例ではその報告例は少ない.今後白血病の治療の進歩とともに成人においてもmeningeal leukemiaの発症頻度は増加するものと思われる.著者らは54才の急性白血病の男性において,約11カ月の経過中に2度の完全緩解をきたし,初回の緩解中に高度の頭痛,嘔気,嘔吐を訴え,髄液所見で脳圧亢進,細胞数増加,ギムザ染色で骨髄芽球を確認し, meningeal leukemiaと診断し,治療としてmethotrexate (Amethopterin) 10mg/週を髄腔内に計8回の注入で臨床症状の消失,髄液所見の改善を得た1例を報告した.