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Biomedical subjects

M Tokuda

Publications and source records attributed to M Tokuda.

At least 163 records · Page 9Linked to original sources
PubMed1989

Small intestinal perforation in Wegener's granulomatosis.

Wegener's granulomatosis is a disease characterized by necrotizing vasculitis and granulomatous inflammation. Gastrointestinal (GI) involvement is uncommon in this disorder. Only a few cases of perforation of GI tract have been reported, but vasculitis has not been demonstrated to be a cause of perforation in these cases. We report a case of Wegener's granulomatosis in which a single perforation in the terminal ileum was disclosed on laparotomy and active necrotizing vasculitis was found in the submucosal layer of the resected specimen.

Adult↗
PubMed1989

The role of Ca2+ and protein kinase C in the differentiation of HL-60 cells induced by 1 alpha,25(OH)2D3 and diltiazem.

The roles of calcium (Ca2+) and protein kinase C in the differentiation of HL-60 cells induced by 1 alpha,25(OH)2D3 (D3) and/or a Ca2+ antagonist, diltiazem(D-cis, L-cis), were elucidated. D3 and diltiazem (100 microM) inhibited cell proliferation, and diltiazem enhanced the D3-induced differentiation. There was no difference in potency between the two isomers of diltiazem in the enhancing activity, in spite of their different pharmacological activity. The concentration of free Ca2+ in the HL-60 cells following D3 and/or diltiazem treatment significantly increased. A protein kinase C inhibitor, H-7, inhibited the phenotypic differentiation induced by D3. These results suggest that Ca2+ and protein kinase C play an important role in the differentiation of HL-60 cells induced by D3 and diltiazem.

Calcitriol↗
PubMed1987

Identification of a new in vitro substrate of tyrosine protein kinase.

Recent studies in our laboratory [Tokuda, M., Khanna, N.C., Aurora, A., & Waisman, D. M. (1986) Biochem. Biophys. Res. Commun. 139, 910-917] have identified in membranes of rat spleen two tyrosine protein kinases named TPK-I and TPK-II. In this paper the identification of the Ca2+ binding protein CAB-48 as a major in vitro substrate of TPK-II is reported. TPK-II catalyzed the incorporation of 0.73 mol of phosphate/mol of CAB-48. Phosphoamino acid analysis revealed that phosphorylation of CAB-48 was specific for tyrosine residues. Phosphorylation of CAB-48 by TPK-I (rat spleen), protein kinase C, casein kinase I, casein kinase II, cAMP-dependent protein kinase, or calcium calmodulin dependent protein kinase was not observed.

Amino Acids↗
PubMed1987

The 48 kDa Ca2+-binding protein of bovine brain.

A Ca2+-binding protein of molecular mass 48 kDa and named 'CAB-48' has been purified from bovine brain 100,000 g supernatant. About 30 mg of CAB-48 was purified from 1 kg of bovine brain. The protein has been characterized with respect to its physical, chemical and Ca2+-binding properties. It has an apparent molecular mass of 48 kDa by SDS/polyacrylamide-gel-electrophoresis and 75.2 kDa from sedimentation-velocity and Stokes-radius data. The acidic nature of the molecule is suggested by its pI of 4.7. In the presence of 3.0 mM-MgCl2 and 150 mM-KCl, CAB-48 binds 1.0 mol of Ca2+/mol of protein with an apparent Kd of 15 microM. A tyrosine protein kinase partially purified from rat spleen catalysed the incorporation of 0.73 mol of phosphate/mol of CAB-48, and phosphoamino acid analysis revealed that phosphorylation of CAB-48 was specific for tyrosine residues.

Amino Acids↗
PubMed1987

Purification and characterization of the 27,000 Da calcium-binding protein of bovine brain.

A Ca2+-binding protein named CAB-27 was purified from bovine brain 100,000 g supernatant. The protein has a molecular mass of 27,000 Da as determined by SDS/polyacrylamide-gel electrophoresis and 35,500 Da by sedimentation-coefficient and Stokes-radius analysis. The protein contains about 26% Glx and Asx and 13% basic residues. The acidic nature of the molecule is confirmed by its pI of 4.80. In the presence of 3 mM-MgCl2 and 150 mM-KCl, CAB-27 binds 2.0 mol of Ca2+/mol of protein, with an apparent Kd of 0.2 microM. Ca2+-binding is unaffected by prior incubation of the protein at 80 degrees C for 2 min. Brain contains about 130 mg of CAB-27/kg. Immunoblotting identified CAB-27 in several bovine tissues; it appears to be particularly rich in brain and kidney. In addition, CAB-27 is identified as an inhibitor of bovine pancreas phospholipase A2 in vitro. The inhibitory activity of CAB-27 was 20-fold less potent than lipocortin. On the basis of the Ca2+-binding properties, intracellular concentration and tissue distribution of this protein, we suggest that CAB-27 may be an important intracellular Ca2+ receptor.

Amino Acids↗
PubMed1987

Glucose tolerance factor stimulates 3-O-methylglucose transport into isolated rat adipocytes.

Glucose tolerance factor partially purified from yeast extract powder stimulated [U-14C]-D-glucose uptake to a level 5.6 times greater than the basal level in the absence of insulin in isolated adipocytes prepared from rats fed with normal laboratory chow. The factor also stimulated 3-O-methylglucose transport 2.2-fold from the basal level in the absence of insulin, but not in the presence of 8 nM insulin. Kinetic analysis revealed that glucose tolerance factor increased 3-O-methylglucose transport by decreasing the Ks value for 3-O-methylglucose with little change in the Vmax.

3-O-Methylglucose↗
PubMed1987

Comparison of calregulins from vertebrate livers.

Calregulins were purified from bovine, rabbit and chicken liver, and their structural properties were compared. Significant differences between the three calregulins include a lower Mr for chicken calregulin (57,000) than for rabbit and bovine calregulin (63,000), and the glycosylation of only bovine calregulin. Amino acid composition and peptide maps of the three calregulins were very similar. No major differences were detected in the Ca2+-binding properties of the three proteins. Zn2+-induced changes in calregulin conformation and hydrophobicity monitored by intrinsic protein fluorescence and the hydrophobic fluorescent probe 8-anilino-1-naphthalenesulphonate were very similar, suggesting that the Zn2+-dependent increase in the hydrophobicity of bovine, rabbit and chicken calregulin was conserved. These studies more fully define what is a calregulin, demonstrate that calregulin is a relatively invariant constituent of vertebrate liver, and indicate that calregulin structure has been highly conserved in bovine, chicken and rabbit liver.

Amino Acid Sequence↗
PubMed1987

Purification of three forms of lipocortin from bovine lung.

Experimental conditions are described for simultaneous purification of three forms of lipocortin (lipocortin I, lipocortin II and lipocortin-85) from bovine lung. The procedure yields milligram quantities of all three lipocortins. Using antisera against lipocortin I and lipocortin II, purified proteins show no cross contaminations. All forms of lipocortin exhibit equal potency as in vitro bovine pancreatic phospholipase A2 inhibitors. Protein kinase C catalyzes the in vivo incorporation of about 1.0, 0.7 and 0.4 mole of phosphate per mole of lipocortin I (p35), lipocortin II (p36) and lipocortin-85 (p36 oligomer) respectively. The phosphorylation is specific for protein kinase C and is dependent on the presence of both calcium and phospholipids. While lipocortin I is phosphorylated on threonine residues, lipocortin II and lipocortin-85 are phosphorylated on serine residues.

Animals↗
PubMed1987

Identification of bovine brain calcium binding proteins.

Three peaks of calcium binding activity have been identified by the Chelex-100 calcium binding assay of the fractions from DEAE cellulose chromatography of 100,000 X g supernatant of bovine brain. These calcium binding activity peaks have been subjected to extensive purification and three novel calcium binding proteins (Mr 27,000, Mr 48,000 and Mr 63,000) and two previously characterized proteins (calcineurin and calmodulin) have been identified as components of calcium binding activity peaks. Analysis of the calcium binding properties of the novel proteins by equilibrium dialysis suggests these proteins may be intracellular calcium receptors.

Animals↗
PubMed1987

Mutagenicity-enhancing effect of quercetin on the active metabolites of 2-acetylaminofluorene with mammalian metabolic activation systems.

The effects of quercetin on the mutagenicity of 2-acetylaminofluorene (AAF) and its 3 active metabolites, N-hydroxy-AAF (N-OH-AAF), aminofluorene (AF) and N-acetoxy-AAF(N-OAc-AAF) were investigated. The mutagenicity assays were carried out with Salmonella typhimurium TA98, and S9, microsomes and cytosol were used as metabolic activation systems. In the presence of S9, quercetin enhanced the mutagenicity of AAF, N-OH-AAF, AF and N-OAc-AAF by 6.9-, 4.3-, 3.6- and 3.9-fold, respectively. Quercetin enhanced the mutagenicity of these substrates with microsomes, whereas it depressed the mutagenicity of these substrates with cytosol. From these results, it seemed probable that quercetin promotes the N-hydroxylation and deacetylation in the microsomes, whereas it inhibits the deacetylation in the cytosol. It was shown that in the metabolism of AAF and its metabolites, quercetin modulates the balance between the mutagenicity activation and inactivation processes, which is catalysed by the enzymes in the microsomes and cytosol, and causes enhancement of the mutagenicity of AAF.

2-Acetylaminofluorene↗
PubMed1987

Enhancement of the mutagenicity of 2-acetylaminofluorene by flavonoids and the structural requirements.

The enhancing effects of 12 kinds of flavonoids on the mutagenicity of 2-acetylaminofluorene (AAF) in Salmonella typhimurium TA98 were investigated. In the mixed applications of AAF (22.4 nmoles/plate) with flavonoids (31.4-45.0 nmoles/plate) in the presence of a mammalian metabolic activation system (S9 mix), morin, galangin, flavonol, kaempferol, quercetin and myricetin enhanced the mutagenicity of AAF by 3.3-10.2-fold. The potency of the mutagenicity enhancing effects increased in the described order. For the mutagenicity-enhancing effects of the flavonoids on AAF, the flavonol structure, including the free 3-hydroxyl group and the 2,3-double bond, were essential. In the quercetin analogues, the 5-hydroxyl group was also essential. Further, the numbers of the hydroxyl groups substituted at the 3', 4' and 5'-positions in the B-ring contributed to an increase of the enhancing effect, whereas the substitution of a hydroxyl group at the 2'-position depressed the potency of the effect.

2-Acetylaminofluorene↗
PubMed1987

Mutagenicity modulating effect of quercetin on aromatic amines and acetamides.

The effect of quercetin on the mutagenicity of 32 kinds of aromatic amines and their acetamides were investigated using Salmonella typhimurium TA98 with a mammalian metabolic activation system (S9 mix). Quercetin enhanced the mutagenicity of the tricyclic aromatic amines (aminofluorene, aminoanthracene and aminophenanthrene) and their acetamides by 1.2-5.9-fold. Whereas, quercetin depressed the mutagenicity of aniline derivatives, biphenyl derivatives, and bi- and tetra-cyclic amino derivatives. The modulation of mutagenicity of Trp-P-1, Trp-P-2, Glu-P-1 and Glu-P-2 (heterocyclic amines) by quercetin were liable to be affected by the content of S9 in the S9 mix. It seems that quercetin does not have the same effect as norharman, because quercetin did not enhance the mutagenicity of aniline. It is suggested that the modulation of the mutagenicity of aromatic amines and acetamides is caused by the modulation of the balance between the mutagenic activation and inactivation in the metabolism of these amines and acetamides in the presence of quercetin. In this modulation, quercetin may participate through its effects on the promotion of N-hydroxylation and the inhibition of arylhydroxylation and transacylation. The presence of tricyclic aromatic rings of amines and acetamides is a structural requirement for the mutagenicity enhancement by quercetin.

Amides↗