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K Nishizawa

Publications and source records attributed to K Nishizawa.

At least 19 recordsLinked to original sources
PubMed1992

Phosphorylation by actin kinase of the pointed end domain on the actin molecule.

Fragmin from plasmodium of Physarum polycephalum binds G-actin and severs F-actin in the presence of Ca2+ over 10(-6) M. The fragmin-actin complex consisting of fragmin and G-actin nucleates actin polymerization and caps the barbed (fast growing) end of F-actin, regardless of the concentrations of Ca2+, and the actin filaments are shortened. Actin kinase purified from plasmodium abolishes the nucleation and capping activities of the complex by phosphorylating actin of the fragmin-actin complex (Furuhashi, K., and Hatano, S. (1990) J. Cell. Biol. 111, 1081-1087). This inactivation of the complex leads to production of long actin filaments. We obtained evidence that Physarum actin is phosphorylated by actin kinase at Thr-201, and probably at Thr-202 and/or Thr-203, with 1 mol of phosphate distributed among them. This finding raises the possibility that the site of phosphorylation, Thr-201 to Thr-203, is positioned on the pointed (slow growing) end domain of the actin molecule, because growth of actin filaments from the fragmin-actin complex occurs only from the pointed end. These observations are consistent with a model of the three-dimensional structure of G-actin. Inactivation of the fragmen-actin complex may follow phosphorylation of the pointed end domain of actin.

Actins↗
PubMed1992

Two different protein kinases act on a different time schedule as glial filament kinases during mitosis.

Glial fibrillary acidic protein (GFAP) is a component of glial filaments specific to astroglia. We now report the spatial and temporal distributions of four phosphorylated sites in the GFAP molecule during mitosis of astroglial cells, determined by antibodies which can distinguish phosphorylated epitopes from non-phosphorylated-epitopes. Immunofluorescence microscopy showed that the Ser8 residues in the entire cytoplasmic glial filament system are initially phosphorylated when the cells enter mitosis. In cytokinesis, the phosphoSer8 residues become dephosphorylated, whereas Thr7, Ser13 and Ser34 in glial filaments at the cleavage furrow become the preferred sites of phosphorylation. The cdc2 kinase purified from mitotic cells can phosphorylate GFAP at Ser8 but not at Thr7, Ser13 or Ser34, in vitro. These results suggest that cdc2 kinase acts as a glial filament kinase only at the G2-M phase transition while other glial filament kinases are probably activated at the cleavage furrow before final separation of the daughter cells.

Amino Acid Sequence↗
PubMed1992

Renal dehydropeptidase-I stability of LJC 10,627, a new carbapenem antibiotic.

LJC 10,627 is a new parenteral carbapenem antibiotic. LJC 10,627 stability against human renal dehydropeptidase-I was compared with that of imipenem. Hydrolysis of this compound was not detectable by spectrophotometrical assay. Even after a 2-h incubation of antibiotics with this enzyme at 30 degrees C, the concentration of LJC 10,627 remained at 92.3% of the initial concentration, whereas imipenem completely disappeared. Thus, it was found that this compound was highly stable against human renal dehydropeptidase-I. Furthermore, LJC 10,627 had a low affinity for this enzyme, as indicated by the high Ki value (0.38 mM).

Animals↗
PubMed1992

Constitutive production of angiotensin converting enzyme from rheumatoid nodule cells under serum free conditions.

Angiotensin converting enzyme was assayed in serum free culture supernatants from unstimulated rheumatoid nodule cells. Angiotensin converting enzyme was released spontaneously and the angiotensin converting enzyme derived from rheumatoid nodule cells was suppressed in a dose and time dependent manner by the protein synthesis inhibitor cycloheximide. These data suggest the constitutive de novo synthesis of angiotensin converting enzyme by rheumatoid nodule cells.

Adult↗
PubMed1992

[Effects of Kamikihi-To on autonomic imbalances in SART-stressed (repeated cold-stressed) mice].

The effects of Kamikihi-To (KMK), a traditional Chinese medicine, on autonomic imbalances were evaluated in SART-stressed (repeated cold-stressed) mice. These animals exhibited decreases in pain threshold and contraction of duodenum by acetylcholine, and they showed changes in their electrocardiogram and hematological parameters. All symptoms are thought to be caused by dysautonomia. KMK in dosages of 0.5 and 1.0 g/kg were administered to mice once a day for 8 consecutive days. SART stress was induced from the second day. KMK prevented the decrease in the pain threshold and contraction of the duodenum, although it had no effect on the electrocardiographic or hematological changes. KMK had no similar effect on unstressed mice. This data suggests that KMK might be useful for the treatment of clinical autonomic imbalances.

Acetylcholine↗
PubMed1991

Phosphorylation of keratin intermediate filaments by protein kinase C, by calmodulin-dependent protein kinase and by cAMP-dependent protein kinase.

Keratins, constituent proteins of intermediate filaments of epithelial cells, are phosphoproteins containing phosphoserine and phosphothreonine. We examined the in vitro phosphorylation of keratin filaments by cAMP-dependent protein kinase, protein kinase C and Ca2+/calmodulin-dependent protein kinase II. When rat liver keratin filaments reconstituted by type I keratin 18 (molecular mass 47 kDa; acidic type) and type II keratin 8 (molecular mass 55 kDa; basic type) in a 1:1 ratio were used as substrates, all the protein kinases phosphorylated both of the constituent proteins to a significant rate and extent, and disassembly of the keratin filament structure occurred. Kinetic analysis suggested that all these protein kinases preferentially phosphorylate keratin 8, compared to keratin 18. The amino acid residues of keratins 8 and 18 phosphorylated by cAMP-dependent protein kinase or protein kinase C were almost exclusively serine, while those phosphorylated by Ca2+/calmodulin-dependent protein kinase II were serine and threonine. Peptide mapping analysis indicated that these protein kinases phosphorylate keratins 8 and 18 in a different manner. These observations gave the way for in vivo studies of the role of phosphorylation in the reorganization of keratin filaments.

Amino Acids↗
PubMed1991

Functional characterization of SV40-transformed adherent synovial cells from rheumatoid arthritis.

A total of 14 transformed cell clones were obtained by micro-injecting origin-defective SV40 DNA into three types of cloned adherent synovial cells (ASC) (dendritic cells (DCs), macrophage-like cells (MCs), and fibroblast-like cells (FCs)) from two rheumatoid arthritis patients (five DC clones (SV40-DCs), five MC clones (SV40-MCs) and four FC clones (SV40-FCs)). All the transformed cell nuclei expressed SV40-specific T antigen. The cells which formed a colony had a few times shorter doubling time than the original cells. IL-1 alpha, IL-1 beta and prostaglandin E2 were detected in the culture supernatant from the unstimulated transformed cells like untransformed cells. The SV40-DCs showed the most potent accessory cell function in oxidative mitogenesis assay among the three types of SV40-ASCs. Granulocyte macrophage colony stimulatory factor (GM-CSF) was detected only in the culture supernatant from the SV40-MCs without stimulation. Extensive phenotypic analysis revealed relatively cell-specific markers. SV40-DCs were HLA-DP+ and glial fibrillary acidic protein positive. SV40-MCs stained positive for 5'-nucleotidase and nonspecific esterase. These transformed ASCs retained much of the original cellular physiology of rheumatoid arthritis (RA) ASCs and may be a useful tool for characterizing the role of ASCs in the pathogenesis of RA.

Adult↗
PubMed1991

[Clinical evaluation of imipenem/cilastatin sodium against severe infections complicating hematological disorders and solid tumors].

Imipenem/cilastatin sodium (IPM/CS) was administered to a total of 67 patients with severe infections complicating hematological disorders and solid tumors. Fifty patients are included in the present analysis of efficacy and 64 in that of safety. 1. Out of 31 patients with hematological disorders, responses were excellent in 10 patients, good in 10 patients, and the efficacy rate was 64.5%. Out of 19 patients with solid tumors, responses were excellent in 8 patients, good in 8 patients and the efficacy rate was 84.2%. 2. For patients whose responses to other antibiotics had been poor, the efficacy rate was 59.3% in the group with hematological disorders and 62.5% in the group with solid tumors. 3. The relationship between the neutrophil count and efficacy was studied in the patients with hematological disorders. The efficacy rate for 8 patients whose neutrophil counts were 500/mm3 or less was 75.0%. 4. For the patients with hematological disorders, the efficacy rate for patients from whom causative organisms were isolated was 70.0% and that for patients for whom they were unknown was 61.9%. 5. Adverse reactions were observed in 3 patients and abnormal laboratory test results in 2 patients. However, they were mild and disappeared after discontinuation of this drug. From these results, IPM/CS is considered to be a useful antibiotic for the treatment of severe infections complicating hematological disorders and solid tumors.

Adolescent↗
PubMed1991

[Neural plasticity after neonatal hypoxic and ischemic insult in rats].

Rats with huge porencephaly occupying the left cerebral hemisphere were used for this study. Porencephaly was caused experimentally by the ligation of the left common carotid artery and subsequent hypoxic exposure at the age of 7 days. A large band of horseradish peroxidase (HRP) positive fibers was found crossing at the pyramidal decussation to reach the contra-lateral corticospinal tract and the deeper part of the funiculus, in the cervical cord. However, a small band of HRP positive fibers was noticed to reach the ipsilateral corticospinal tract without crossing at the pyramidal decussation. This result indicates that the developing pyramidal neurons in the right hemisphere carry the plasticity even after suffering from considerable hypoxia.

Animals↗
PubMed1991

[A case of Günther vena caval filter insertion for recurrent pulmonary embolism].

We report that the Günther vena caval filter was successfully inserted in a case of recurrent pulmonary embolism resulting from ilio-femoral venous thrombosis. A 42-year-old woman was admitted to Osaka City University Medical School Hospital for dyspnea and chest pain on April 19, 1988. Pulmonary perfusion scintigraphy and pulmonary arterial angiography proved pulmonary emboli. The combination therapy of heparin and urokinase was performed, and her condition markedly improved. Then an ilio-femoral venography revealed only iliac vein compression but no thrombi. Therefore she was followed as an out patient with anticoagulant therapy. Nevertheless on April 10, 1989 she was admitted again complaining dyspnea and cyanosis. By venography at this time, some filling defects due to thrombi in right iliac vein were found. Therefore, we decided the insertion of the Günther vena caval filter for recurrent pulmonary embolism using Seldinger method via right internal jugular vein. We expect that the Günther vena caval filter will be useful for preventing pulmonary embolism resulting from ilio-femoral venous thrombosis because its procedure is easy, non-invasive and without significant complications.

Adult↗
PubMed1979

Alterations in the survival of X-irradiated cells by 2,4-dinitrophenol depending on ATP deprivation.

The dose-survival curve of cultured melanoma cells was changed by post-irradiation treatment with 2,4-dinitrophenol (DNP). The parameters of the curves were Do = 147 R and n = 5 . 6 for untreated cells and Do = 143 R, n = 7 . 9 and Do = 142 R, n = 2 . 0 for the cells treated with 10(-5) M DNP and 5 x 10(-5) M DNP in phosphate-buffered saline, respectively. The content of ATP in the cell decreased to 5% of the control level after treatment with either concentration of DNP. The recovery of ATP content was rapid and complete after 2 hours' incubation in culture medium after the removal of 10(-5) M DNP, but was retarded and incomplete after 4 hours with 5 x 10(-5) M DNP. Thus prolonged ATP deprivation with a high concentration of DNP results in an inhibition of recovery and a reduction in the n-value.

Adenosine Triphosphate↗
PubMed1979

Calcium-dependent process in reduction of cell surface charge after x-irradiation.

The electrophoretic mobility (EPM) of rat erythrocytes and cultured melanoma cells decreased with time after X-irradiation in the presence of calcium at concentrations higher than 10 (-5) M. At 37 degrees C, the presence of calcium for the first 20 min of exposure was suffcient to induce the EPM reduction, and Ca 2+ administration subsequent to Ca 2+ -free incubation for 30 min following irradiation had no effect on EPM. At lower temperatures, from 10 down to 20 degrees C however, the effect of calcium on the reduction of EPM decreased drastically. If the cells were kept Ca 2+ -inonophore A23187 also induced to decrease in EPM only in the presence of Ca 2+. These results revealed the transitory existence of membrane condition reactive to extracellular Ca 2+ immediately after X-irradiation, which can be postponed at low temperatures. The reduction of EPM by Ca 2+ -ionophore might suggest that the influx of Ca 2+ is a step in the reduction of EPM after X-irradiation.

Animals↗
PubMed1979

Early decrease in hyaluronidase-sensitive cell surface charge during the differentiation of Friend erythroleukemic cells by dimethyl sulfoxide.

Early membrane events in erythroid differentiation were investigated by means of cell electrophoresis utilizing cultured Friend erythroleukemia cell clones of different inducibility. The cell electrophoretic mobility decreased by 18% within 30 min of treatment with 1.5% dimethyl sulfoxide (DMSO) in highly inducible clones but not in noninducible clones. The reduced mobility persisted for 5 days of incubation with DMSO until hemoglobin synthesis. DMSO treatment for less than 16 hr and subsequent incubation without the drug resulted in the complete recovery of the mobility and no hemoglobin synthesis. Longer exposure to DMSO resulted in the loss of recovery of mobility and an increasing fraction of benzidine-positive cells seen on Day 5. Measurement of the electrophoretic mobility after the removal of acidic sugars by their specific enzymes suggested that hyaluronidase-sensitive negative charges were lost from the cell surface only in highly inducible clones. The mobility reduction associated with hyaluronic acid was also caused by other potent inducers (sodium butyrate, N-methylacetamide, and N,N-dimethylacetamide). These results suggest that the decrease in cell surface glycocalyx might be an early step in the induction of differentiation of Friend erythroleukemia cells.

Animals↗