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T Tetsuka

Publications and source records attributed to T Tetsuka.

49 records · Page 3Linked to original sources
PubMed1992

On the mechanism of lipoxygenase-like action of bleomycin-iron complexes.

The mechanism of lipid peroxidation catalyzed by bleomycin (BLM)-iron (Fe) complexes has been studied in vitro using sodium linoleate as a substrate. BLM-Fe(II)-O2 and BLM-Fe(III) complexes catalyze lipid peroxidation concomitantly with singlet oxygen evolution. The results from spin trapping methods and gas chromatography-mass spectroscopy (GCMS) analyses suggest that the initial step of lipid peroxidation catalyzed by BLM-Fe complexes is similar to that of soybean lipoxygenase, viz., hydrogen abstration. However, another mechanism might be concerned in the case of BLM-Fe(II)-O2 complex. BLM-Fe complexes are also capable of enhancing singlet oxygen evolution from the hydrogen peroxide (H2O2)-hypochlorite (OCl-) system.

Bleomycin↗
PubMed1991

Molecular cloning of the murine ST2 gene. Characterization and chromosomal mapping.

The genomic locus of the murine ST2 gene was isolated based on homology with a murine ST2 complementary DNA sequence and its complete nucleotide sequence was determined. The locus is composed of eight exons and seven introns and is approx. 9 kilobase pairs in size. Two Sp1 binding sites are present in the 5' flanking region. The murine ST2 gene, which was expressed only in the growth-stimulated BALB/c-3T3 cells, was mapped to mouse chromosome one, very tightly linked to the interleukin 1 receptor-type 1 locus.

Animals↗
PubMed1991

Cellular mechanism of lithium-induced nephrogenic diabetes insipidus in rats.

One of the mechanisms by which Li evokes polyuria is thought to be impairment of arginine vasopressin (AVP)-sensitive adenylate cyclase (AdC) in cells of the renal collecting duct. To investigate how AdC is influenced by chronic administration of Li, we created nephrogenic diabetes insipidus (NDI) in rats and microdissected the medullary collecting tubule from both control and NDI rats. In the NDI group, the 10(-6) M AVP-stimulated cAMP contents failed to increase completely, and the levels were significantly lower than that of the control group (10.4 +/- 1.4 vs. 48.4 +/- 4.7 fmol/mm, P less than 0.001). Pretreatment with pertussis toxin (PT), an inhibitor of inhibitory G protein (Gi), did not affect the basal cAMP levels in both groups, although it increased AVP-stimulated cAMP production in the NDI group in a dose- and time-dependent manner. AVP-stimulated cAMP production with over 100 ng/ml PT in the NDI group reached the levels observed in the control group. Incubation with cholera toxin, an agonist of stimulatory G protein (Gs), increased the cAMP content in the two groups to almost equal levels. To exclude the possibility that prostaglandin E2 (PGE2) is involved in the cellular mechanism of Li-induced NDI, the effect of indomethacin (Indo) on PT action was examined. However, Indo (10(-5) M) did not influence either the basal or AVP-dependent cAMP contents. From these results it is suggested that Li impairs AVP-sensitive AdC not through inhibition of Gs but through activation of Gi and that PGE2 may not be involved in the cellular pathogenesis of NDI at least in the rat at the step of cAMP formation.

1-Methyl-3-isobutylxanthine↗
PubMed1984

Characteristic expression of glycosphingolipid profiles in the bipotential cell differentiation of human promyelocytic leukemia cell line HL-60.

Changes of glycosphingolipids (GSLs) in the bipotential cell differentiation of human promyelocytic leukemia cell line HL-60 cells were investigated by high-performance thin-layer chromatography (HPTLC), with special reference to morphological and functional changes, such as phagocytosis and nitroblue tetrazolium (NBT) reduction. Nine molecular species of neutral GSLs and 13 or more species of sialo-GSLs, ie, gangliosides, were detected on the HPTLC chromatograms for untreated HL-60 cells. The major components were ceramide dihexoside (CDH), GM3, and sialo-paragloboside (SPG). When HL-60 cells were induced to differentiate into both myeloid mature cells and macrophage-like cells in vitro, no new molecular species of GSLs specific for one of the cell differentiations was induced, but distinctive quantitative changes in the GSL composition were definitely observed between the two cell differentiations. During the myeloid differentiation induced by either dimethylsulfoxide (DMSO) or retinoic acid (RA), CDH, paragloboside (PG), and gangliosides having longer sugar moieties characteristically increased with a concomitant decrease of GSLs with shorter sugar chains, such as ceramide monohexoside (CMH) and GM3, and the GSL composition profile of myeloid differentiation-induced HL-60 cells became more similar to that of normal human granulocytes. However, some marked differences were noted between the induced HL-60 cells and the normal granulocytes, especially in the ganglioside compositions. These differences might reflect either some deficiency in the in vitro myeloid differentiation or some leukemic properties of HL-60 cells. In marked contrast to the change of GSL composition during myeloid differentiation, a remarkable increase of GM3, with a concurrent marked decrease of CDH, was observed in the process of cell differentiation into macrophage-like cells with 12-O-tetradecanoyl-phorbol-13-acetate (TPA), which suggested an increase in the biosynthesis of GM3. These results demonstrate that HL-60 cells express distinct GSL profiles, depending not only on maturation stages but also on differentiation directions.

Cell Line↗
PubMed1978

Stimulation of prolyl hydroxylase activity by bleomycin.

The activity of purified prolyl hydroxylase (proline, 2-oxoglutarate dioxygenase, EC 1. 14. 11. 2) was enhanced 3 approximately 8-fold at a low concentration of ferrous ion (1 X 10(-5 M) by addition of bleomycin, a glycopeptide antibiotic with antineoplastic activity and a side effect of producing pulmonary fibrosis. The maximum stimulation was attained at a concentration of 15 microgram/ml bleomycin (about 1 X 10(-5) M), which was approximately equimolar with the ferrous ion, one of the cofactors of this enzyme. Addition of bleomycin to the assay mixture resulted in a change of the optimal concentration of ferrous ion from 2 X 10(-3) M to 1 X 10(-5) M. Changing the order of addition of ferrous ion, enzyme and bleomycin in assay medium before incubation at 37 degrees C, the stimulatory activity was varied. Blemycin A2Cu++(Cu++-chelated bleomycin), which scarcely complexed with Fe++, had no enhancing effects on the enzymatic activity. We discuss the possible reasons as to why the activity of prolyl hydroxylase was enhanced by addition of bleomycin in the assay mixture.

Animals↗
PubMed1977

Different responses to some stimulators of prolyl hydroxylase activities in various rat organs.

Prolyl hydroxylase (proline,2-oxoglutarate dioxygenase, EC 1.14.11.2) of soluble fraction (105 000 X g supernatant) of rat granulation tissues was markedly enhanced by addition of nucleoside triphosphates to the assay medium. But the stimulatory activities of nucleoside triphosphates were very different in fractions derived from tissues of rat. In skin, lung or whole fetal tissues other than granuloma, GTP enhanced the enzymatic activity by 3-4 fold. On the other hand, in kidney, liver and spleen tissues it brought about no enhancement. The same results were obtained even if ATP regenerating system was added in the assay medium. The stimulatory effect of nucleoside triphosphates was not seen with the soluble fraction of liver, but it appeared with the enzyme fraction purified by affinity column chromatography. The same phenomenon was observed by addition of bovine serum albumin instead of nucleoside triphosphates as stimulator. We discuss the possible reasons as to why the responses of the enzyme to stimulators were quite different among various tissues.

Adenosine Triphosphate↗
PubMedDate not supplied

Change in inferior vena caval diameter detected by ultrasonography during and after hemodialysis.

The diameter of the inferior vena cava (IVC) measured by ultrasonography is used as a parameter to estimate right sided cardiac function and central venous pressure. In the current study the IVC diameter during and after hemodialysis (HD) was measured in chronic HD patients to explore the determinant factors of the diameter, and these results were obtained: 1) the maximal diameter of the IVC during quiet expiration (IVCe) can be a marker of circulating blood volume during as well as after HD, because the linear correlation between IVCe and circulating blood volume during and after HD were significant and almost identical; 2) the amount of ultrafiltration is the major determinant of IVCe during HD, because IVCe and circulating blood volume decreased in parallel with the amount of ultrafiltration during HD; and 3) since the recovery of IVCe and circulating blood volume, which correlated with the increase in serum protein concentration during HD, was almost complete while the body weight remained unchanged after HD, plasma refilling rather than body fluid retention was considered important in the recovery of IVCe and circulating blood volume after HD.

Adult↗