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Biomedical subjects

K Isono

Publications and source records attributed to K Isono.

At least 253 records · Page 14Linked to original sources
PubMed1992

A new inhibitor of protein kinase C, RK-1409 (7-oxostaurosporine). I. Taxonomy and biological activity.

A novel inhibitor of protein kinase C was found in the fermentation of a soil actinomycete, strain RK-1409. According to the taxonomic studies, the producing strain was designated as Streptomyces platensis subsp. malvinus RK-1409. The protein kinase C inhibitor, RK-1409 (7-oxostaurosporine) inhibited the morphological change of a human chronic erythroleukemia cell, K-562, induced by phorbol 12,13-dibutyrate (PDBu) at the concentration of 10 ng/ml. The concentration of 3 ng/ml inhibited the activity of protein kinase C in vitro. RK-1409 inhibited the cell cycle progression at G2 phase of K-562 cells.

Alkaloids↗
PubMed1992

Respiratory burst induced by phorbol ester in the presence of tautomycin, a novel inhibitor of protein phosphatases.

Phorbol dibutyrate induced a nitroblue tetrazolium-reducing reaction in differentiated HL-60 cells, which was inhibited by protein kinase inhibitors such as staurosporine and H-7. ID50 of staurosporine and H-7 were 1.4 ng/ml and 0.19 mM, respectively. When tautomycin, an inhibitor of protein phosphatases, was added with the kinase inhibitors, the nitroblue tetrazolium-reducing reaction again appeared. ID50 of staurosporine was 510 ng/ml in the presence of tautomycin. Tautomycin itself weakly induced the reaction, which was inhibited by kinase inhibitors. Such a competitive effect between tautomycin and staurosporine was not observed in a cell-free system of protein kinase C. Okadaic acid had the same effect as tautomycin. The similar results were obtained when respiratory burst was quantitated by measuring H2O2 produced by canine peripheral neutrophils. The mechanism of competitive effect of tautomycin and staurosporine on respiratory burst is discussed.

Alkaloids↗
PubMed1992

Effects of tautomycin, a protein phosphatase inhibitor, on recycling of mammalian cell surface molecules.

The effects of tautomycin, a protein phosphatase inhibitor, on recycling of cell surface molecules were studied with transferrin receptor (TFR) of human myeloid leukemia K562 cells and with CD4 of murine thymocytes. Tautomycin increased expression of TFR of K562 cells whereas phorbol dibutylate (PDBu) decreased it. Tautomycin inhibited PDBu-induced down-regulation of CD4 although it did not induce up-regulation. Okadaic acid also inhibited down-regulation of CD4 which was induced by PDBu. The results suggest that certain inhibitors of protein phosphatases preferentially inhibit endocytosis of cell surface molecules.

Alkaloids↗
PubMed1992

Evaluation of liver tumors using fluorine-18-fluorodeoxyglucose PET: characterization of tumor and assessment of effect of treatment.

To evaluate glucose metabolism in patients with tumors involving the liver, 35 patients with liver lesions had PET using 18F-2-fluoro-2-deoxy-D-glucose (FDG). FDG (148 MBq) was injected and radioactivity of the tumor was scanned dynamically by PET. The rate constants (k1, k2, k3, k4) of FDG in a metabolic model were calculated. The results were compared to hexokinase activity in the excised tumor specimens. k3 was found to reflect tumor hexokinase activity. When k3 was used as an index (cut-off value: 0.025), it was possible to distinguish benign and malignant tumors. k4 was significantly higher in hepatocellular carcinoma. By using k3 and k4 as indices, one could assess the degree of differentiation of hepatocellular carcinoma. After treatment, k3 decreased according to the effectiveness of therapy and thus may be a useful index for quantitatively assessing tumor viability.

Adenoma, Bile Duct↗
PubMed1992

[Effects of angiotensin peptides on airway epithelial ion transport and its modulation by angiotensin converting enzyme].

To study the effects of angiotensin (ANG) peptides on airway epithelial ion transport function, we evaluated the bioelectric properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. Addition of ANG I, II and II dose-dependently increased short-circuit current (Isc) and transepithelial potential difference, an effect that was more pronounced with addition to the submucosal solution than to the mucosal solution, with rank order of potency of ANG II greater than or equal to ANG II much greater than ANG I. The ANG-induced increase in Isc was not altered by the Na channel blocker amiloride, but was greatly reduced by the CI channel blocker diphenylamine-2-carboxylate and Cl-free medium. The response of Isc to ANG I was reduced by MK422, an angiotensin converting enzyme inhibitor, in a dose-dependent fashion. These results suggest that ANG II and III selectively stimulate Cl secretion across airway epithelium and that ANG I may exert its effect after its conversion to ANG II by angiotensin converting enzyme.

Angiotensin I↗
PubMed1992

[The effect of FK506 on segmental pancreas allograft in mongrel dogs].

FK506 is a potent immunosuppressive agent on experimental and clinical organ transplantation. We studied the the effect of this agent on segmental pancreas allograft in mongrel dogs. Graft survival was prolonged significantly with continuous administration of FK506, 0.3mg/kg/day intramuscular and 1.0mg/kg/day orally. However such symptoms as loss of appetite, nausea and extreme emaciation were observed and caused death. While bolus therapy of FK506 (3 days administration with the dose of 1.0mg/kg i.m. from 4 to 6 day postoperatively) showed the same immunosuppressive effect as continuous therapy and less side effect. Furthermore it was suggested that FK506 plasma levels were concerned with the appearance of side effect. In conclusion, the administration of FK506 with plasma level monitoring was thought to be useful on pancreas transplantation.

Animals↗
PubMed1992

The anti-asthmatic agent KC 404 inhibits sodium absorption by canine tracheal epithelium.

To elucidate the effect of KC 404, an anti-asthmatic agent, on electrolyte transport across airway mucosa, we studied electrical properties of canine tracheal epithelium under isometric conditions in vitro. Addition of KC 404 decreased short-circuit current, transepithelial potential difference and cell conductance, accompanied by the decrease in 22Na flux from submucosa to mucosa. The KC 404-induced decrease in short-circuit current was inhibited by amiloride but not by diphenylamine-2-carboxylate. These results suggest that KC 404 selectively inhibits Na absorption by airway epithelium, thereby leading to the increase in water content in the respiratory lumen.

Absorption↗
PubMed1992

[Endoscopic treatment of esophageal cancer].

With the advance of endoscopic equipment the number of superficial cases of esophageal cancer has been increasing dramatically. It has been clarified as to which cancer can be treated as an early cancer with desirable results as in gastric cases. Endoscopic treatment for early cancer already established in gastric or colorectal cases have been applied to esophageal cases with nationwide popularity. Especially endoscopic mucosal resection, which can assure accurate pathological findings, can be the treatment of choice for endoscopic procedures for early cancer. In this paper, our methodology of endoscopic treatment of early esophageal cancer is introduced and our endoscopic approach to advanced cases which is still to be established is reported.

Esophageal Neoplasms↗
PubMed1992

[Postoperative MRSA infections in digestive tract surgery].

MRSA strains were first isolated in 1981 and have increased markedly from 1985 in our surgical ward. One hundred and ninety four strains of MRSA were isolated and 81 cases developed critical infections which were associated with enterocolitis, pneumonia and sepsis. There were many cases in esophageal cancer patients. Bacteriological features of the MRSA strains clearly changed in 1985 from IV to II coagulase type, accompanied with high resistance for antibiotics. Our management against nosocomial infection for MRSA started from April 1988. The number of MRSA cases decreased in 1989, increased in 1990 and decreased again in 1991. We are confident that our management is effective and we will take further efforts to choose the most adequate antibiotics after surgery in our surgical ward.

Cross Infection↗