Search PubMed⌕ Search

Biomedical subjects

M Tsuda

Publications and source records attributed to M Tsuda.

At least 415 records · Page 23Linked to original sources
PubMed1990

Characteristics of the H(+)-translocating adenosine triphosphatase of Vibrio parahaemolyticus.

We have characterized H(+)-translocating adenosine triphosphatase (ATPase) in membrane vesicles of Vibrio parahaemolyticus. The ATPase required high concentrations (about 0.5 M) of Na2SO4 (or other salts) for its maximum activity. Magnesium ion stimulated the ATPase activity, but Ca2+ did not. The activity of ATPase was inhibited by tetrachlorosalicylanilide, an H+ conductor, but not by another H+ conductor, carbonylcyanide-m-chlorophenylhydrazone. The activity was strongly inhibited by dicyclohexylcarbodiimide or Zn2+, and partially inhibited by azide, but not at all by vanadate.

Cell Membrane↗
PubMed1990

Peripheral blood neutrophil function in germfree and conventional rats.

The superoxide anion production and the myeloperoxidase activity between polymorphonuclear cells (PMNs) from conventional and germfree rats were compared. Furthermore, the response to recombinant human granulocyte colony stimulating factor (G-CSF) between both groups of rats was also examined. Our present investigation showed that: (1) the basal superoxide anion production by PMNs in germfree rats (2.1 +/- 0.5 nmol/min/1 x 10(6) PMNs) is less than one fourth of that of conventional rats (9.5 +/- 2.9 nmol/min/1 x 10(6) PMNs). (2) the myeloperoxidase activity of PMNs from germfree rats (38.1 +/- 5.2 nmol/min/1 x 10(6) PMNs) is 1.7 times that of conventional rats (22.4 +/- 4.9 nmol/min/1 x 10(6) PMNs). (3) G-CSF administration increased the number of PMN, 12.4 times in the germfree rats compared with 3.9 times in the conventional rats. (4) the PMNs induced by G-CSF do not differ in the superoxide anion producing activity. However the myeloperoxidase activity decreased in the G-CSF induced PMNs of both groups of rats. From our data, the conventional rats could have a more effective killing activity than the germfree rats. Furthermore, germfree rats may be used as a powerful tool for assay of other biological substances relating to immune system and its regulation.

Animals↗
PubMed1990

The isoelectric focusing pattern of desialylated alpha 1-antichymotrypsin of heterozygous alpha 1-antichymotrypsin deficiency and of acute phase plasma.

In an attempt to find a molecular marker for the putative abnormal allele in heterozygous alpha 1-antichymotrypsin (ACT) deficiency (a rare trait associated with early emphysema, childhood asthma and chronic "cryptogenic" liver disease) the isoelectric focusing pattern of neuraminidase treated plasma samples from subjects of ACT deficiency families as well as acute phase plasma were compared. There was no difference in the isoform pattern of plasma from ACT deficiency heterozygotes, normal subjects or patients with acute phase response. However, in acute phase plasma there was a disproportional increase in two isoforms, one of which conceivably may be used to mark the early phase of the acute phase response.

Acute-Phase Reaction↗
PubMed1989

Neurite outgrowth from mouse neuroblastoma and cerebellar cells induced by the protein kinase inhibitor H-7.

The protein kinase inhibitor H-7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride) or staurosporine was found to induce neurite outgrowth from mouse neuroblastoma N18TG2 cells and cultured cerebellar cells by light microscopy. Examination by electron microscopy revealed some morphological differences between the neurites of N18TG2 cells induced by H-7 and dB-cAMP, in which H-7 formed longer and thinner neurites and more abundant localized varicose structures along neurites than dB-cAMP. These results indicate that protein kinase inhibitor itself can act as a potent stimulus for inducing neurite outgrowth in a different manner from dB-cAMP.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Cyclic nucleotides and GTP analogues stimulate light-induced phosphorylation of octopus rhodopsin.

Light-induced phosphorylation of octopus rhodopsin in microvillar membrane was shown to be stimulated by cyclic nucleotides in contrast to vertebrate rhodopsin kinase. Non-hydrolyzable GTP analogues, GTP lambda S and GppNHp, greatly enhanced the light-induced phosphorylation of octopus rhodopsin, but the non-hydrolyzable GDP analogue, GDP beta S, was not effective. These results suggest that rhodopsin A-kinase is involved in regulating the interaction between rhodopsin and G-protein in octopus photoreceptors.

Animals↗
PubMed1989

Rat pineal S-antigen: sequence analysis reveals presence of alpha-transducin homologous sequence.

S-antigen (S-Ag) is a soluble, highly antigenic protein, the administration of which induces autoimmune uveitis. This protein is found in the retina and pineal. Retinal S-Ag from three species has been sequenced. In this study rat pineal S-Ag was sequenced. Clones were isolated from a rat pineal lambda gt11 cDNA library by probing with a 300 bp fragment of mouse retinal S-Ag cDNA containing the 5'-coding region. The largest clone isolated (RPS-118; 1364 bp) contained the entire coding sequence. Comparison of the rat pineal and mouse retinal S-Ag nucleotide sequences indicated a high homology (95%). The deduced amino acid sequence was found to contain 403 residues (congruent to 44 992 Da). Comparison of the rat pineal and mouse retinal S-Ag amino acid sequences also revealed high homology (97%). The similarity of both the nucleotide and amino acid sequences of rat pineal and mouse retinal S-Ag indicates that expression of the S-Ag gene in both tissues is similar. Further analysis of the rat pineal S-Ag sequence indicated that it contained essentially the same major uveitopathogenic region of S-Ag present in bovine retina; minor uveitopathogenic sites were somewhat different. As is true of retinal S-Ag, rat pineal S-Ag contains the same consensus phosphoryl-binding site present in many GTP/GDP-binding proteins and a homologous sequence found in the C-terminus of alpha-transducin. These sequences may play a role in the action of pineal S-Ag in transmembrane signal transduction.

Amino Acid Sequence↗
PubMed1989

A comparative study of the infrared difference spectra for octopus and bovine rhodopsins and their bathorhodopsin photointermediates.

Fourier-transform infrared difference spectroscopy has been used to detect the vibrational modes in the chromophore and protein that change in position and intensity between octopus rhodopsin and its photoproducts formed at low temperature (85 K), bathorhodopsin and isorhodopsin. The infrared difference spectra between octopus rhodopsin and octopus bathorhodopsin, octopus bathorhodopsin and octopus isorhodopsin, and octopus isorhodopsin and octopus rhodopsin are compared to analogous difference spectra for the well-studied bovine pigments, in order to understand the similarities in pigment structure and photochemical processes between the vertebrate and invertebrate systems. The structure-sensitive fingerprint region of the infrared spectra for octopus bathorhodopsin shows strong similarities to spectra of both all-trans-retinal and bovine bathorhodopsin, thus confirming chemical extraction data that suggest that octopus bathorhodopsin contains an all-trans-retinal chromophore. In contrast, we find dramatic differences in the hydrogen out-of-plane modes of the two bathorhodopsins, and in the fingerprint lines of the rhodopsins and isorhodopsins for the two pigments. These observations suggest that while the primary effect of light in the octopus rhodopsin system, as in the bovine rhodopsin system, is 11-cis/11-trans isomerization, the protein-chromophore interactions for the two systems are quite different. Finally, striking similarities and differences in infrared lines attributable to changes in amino acid residues in the opsin are found between the two pigment systems. They suggest that no carboxylic acid or tyrosine residues are affected in the initial changes of light-energy transduction in octopus rhodopsin. Comparing the amino acid sequences for octopus and bovine pigments also allows us to suggest that the carboxylic acid residues altered in the bovine transitions are Glu-122 and/or Glu-134.

Amino Acids↗
PubMed1989

A respiratory-driven and an artificially driven ATP synthesis in mutants of Vibrio parahaemolyticus lacking H+-translocating ATPase.

Mutants of Vibrio parahaemolyticus lacking the H+-translocating ATPase were isolated to evaluate both the role of this enzyme and the possibility of the involvement of other cation-translocating ATPase in the energy transduction in this organism. Dicyclohexylcarbodiimide-sensitive ATPase activity which represents the H+-translocating ATPase was not detected either in the membrane vesicles or in the cytosol of the mutants. Three major subunits, alpha, beta and gamma, of the H+-translocating ATPase were missing in the membranes of the mutants. Although ATP was synthesized in wild type cells when an artificial H+ gradient was imposed, little ATP was synthesized in the mutants. However, we observed a large ATP synthesis driven by the respiration not only in the wild type but also in the mutants. The respiratory-driven ATP synthesis in wild type was inhibited by an H+ conductor, carbonylcyanide m-chlorophenylhydrazone, by about 50%. On the other hand, the ATP synthesis in the mutants was not affected by the H+ conductor. Since this organism possesses a respiratory Na+ pump, Na+-coupled ATP synthesis might take place. In fact, we observed some ATP synthesis driven by an artificially imposed Na+ gradient both in the wild type and the mutant.

Adenosine Triphosphate↗
PubMed1989

Regeneration of bovine and octopus opsins in situ with natural and artificial retinals.

We consider the problem of color regulation in visual pigments for both bovine rhodopsin (lambda max = 500 nm) and octopus rhodopsin (lambda max = 475 nm). Both pigments have 11-cis-retinal (lambda max = 379 nm, in ethanol) as their chromophore. These rhodopsins were bleached in their native membranes, and the opsins were regenerated with natural and artificial chromophores. Both bovine and octopus opsins were regenerated with the 9-cis- and 11-cis-retinal isomers, but the octopus opsin was additionally regenerated with the 13-cis and all-trans isomers. Titration of the octopus opsin with 11-cis-retinal gave an extinction coefficient for octopus rhodopsin of 27,000 +/- 3000 M-1 cm-1 at 475 nm. The absorption maxima of bovine artificial pigments formed by regenerating opsin with the 11-cis dihydro series of chromophores support a color regulation model for bovine rhodopsin in which the chromophore-binding site of the protein has two negative charges: one directly hydrogen bonded to the Schiff base nitrogen and another near carbon-13. Formation of octopus artificial pigments with both all-trans and 11-cis dihydro chromophores leads to a similar model for octopus rhodopsin and metarhodopsin: there are two negative charges in the chromophore-binding site, one directly hydrogen bonded to the Schiff base nitrogen and a second near carbon-13. The interaction of this second charge with the chromophore in octopus rhodopsin is weaker than in bovine, while in metarhodopsin it is as strong as in bovine.

Animals↗
PubMed1989

Macrophage-mediated N-nitrosation of thioproline and proline.

Thioproline (Thiazolidine-4-carboxylic acid) and proline were nitrosated by stimulated mouse macrophages in vitro. A macrophage cell line (J774.1, 1.0 x 10(6)/well, 1 ml) was incubated with Escherichia coli lipopolysaccharide, interferon-gamma and thioproline (5 mM) or proline (5 mM). After 72 hr incubation at 37 degrees C, 4 microM N-nitrosothioproline was produced. The amount of N-nitrosoproline was much lower than that of N-nitrosothioproline. Thioproline and proline inhibited the formation of carcinogenic N-nitrosomorpholine. N-nitrosothioproline and N-nitrosoproline are found as major N-nitroso compounds in human urine. Macrophage mediated N-nitrosation may contribute to the formation of these N-nitrosamino acids in the human body.

Animals↗
PubMed1989

Dual inhibitory effect of bredinin.

Bredinin inhibition of cell growth was investigated in the mouse lymphoma cell line L5178Y. Bredinin caused the accumulation of IMP and the reduction of XMP. It was converted to the 5'-phosphate within the cells. Bredinin 5'-phosphate but not bredinin competitively inhibited both IMP dehydrogenase and GMP synthetase. Thus the inhibition of cell growth is probably due to bredinin 5'-phosphate, which inhibits the consecutive enzyme reactions IMP dehydrogenase and GMP synthetase. These inhibitions result in the accumulation of IMP and the reduction of XMP.

Animals↗
PubMed1989

Accelerated bone resorption in senescence-accelerated mouse (SAM-P/6).

Age-associated changes in the femoral bone and in urine and serum composition were studied to understand the low bone mass in a substrain of senescence-accelerated mouse (SAM), SAM-P/6. Age-matched normal SAM-R/1 mice were used as controls. After 13 weeks of age, the concentration of hydroxyproline in the femur of SAM-P/6 was slightly but significantly lower. The urinary excretion rates of cAMP and calcium were higher in SAM-P/6 throughout the whole experimental period, and those of hydroxyproline and phosphorus were higher after 8 weeks. The serum concentrations of calcium and inorganic phosphorus of SAM-P/6 were higher at 13 and 20 weeks. At 5 weeks, the serum alkaline phosphatase and tartrate-resistant acid phosphatase (TRAP) activities of SAM-P/6 were significantly higher. Furthermore, the serum of SAM-P/6 significantly stimulated calcium release from cultured fetal rat ulna. Since urinary cAMP and TRAP in the serum reflect the circulating level of parathyroid hormone and osteoclastic function, respectively, the present results suggest that, in SAM-P/6, accelerated bone resorption produced by a putative hyperparathyroid state causes the decrease in bone mass.

Aging↗
PubMed1989

The gene for retinal S-antigen (48-kDa protein) maps to the centromeric portion of mouse chromosome 1 near Idh-1.

S-antigen (48-kDa protein) is a soluble protein of the retina and the pineal gland that is believed to play an important role in the visual process. S-antigen is involved in the regulation of the activity of rod photoreceptor-specific cGMP-phosphodiesterase (cGMP-PDE). The activity of this enzyme has been shown to be deficient in the retina of the rd mouse, which is affected by an autosomal recessive disease characterized by degeneration of the photoreceptor cells. The abnormal cGMP-PDE activity could result from, among other things, a lesion in the enzyme itself or in any of the proteins that regulate it, such as the S-antigen. We have used a mouse cDNA clone for the S-antigen to map the corresponding gene, Sag, to mouse chromosome 1 near Idh-1. Since the rd gene is located on mouse chromosome 5, our results suggest that Sag is not the site of the rd mutation.

Animals↗
PubMed1989

Leiomyosarcoma of the transverse colon in a neonate: a rare cause of meconium peritonitis.

A rare case of a newborn infant with leiomyosarcoma of the transverse colon is reported. The condition was associated with meconium peritonitis due to a perforation proximal to a portion of the transverse colon that was completely surrounded by the tumor. The 12 previously published cases of leiomyosarcoma of the colorectum in childhood are reviewed, and the pathogenesis of meconium peritonitis is discussed.

Colonic Neoplasms↗
PubMed1989

Influence of fecal anorexigenic substance (FS-T) on plasma amino acids in Wistar and Zucker obese (fa/fa) rats.

An anorexigenic substance (FS-T), found in feces, isolated and injected intraperitoneally, induced significant feeding suppression in Wistar rats and in genetically obese Zucker rats (fa/fa) and their lean littermates. The concentration of total plasma amino acids 2 h after FS-T injection (the time of maximum feeding suppression) was 71.0, 68.6 and 60.2% of that of controls for Wistar and Zucker obese and lean rats, respectively. By 48 h after injection of FS-T, food intake and the concentration of total plasma amino acids had returned to normal. Plasma tryptophan levels and the ratio of tryptophan to neutral amino acids were also monitored to elucidate the relation between FS-T and appetite. Two h after injection of FS-T, the ratio of tryptophan to neutral amino acids had increased in Wistar rats, while no change was detected in either obese or lean Zucker rats. However, no change was observed in plasma glucagon levels in Wistar rats, but a significant increase was found in both obese and lean Zucker rats at 2 h after FS-T injection.

Amino Acids↗
PubMed1989

Purification and characterization of membrane-bound 5'-nucleotidase of Vibrio parahaemolyticus.

Membrane-bound 5'-nucleotidase from Vibrio parahaemolyticus was solubilized and purified using a nonionic detergent, heptyl-beta-D-thioglucoside, and was characterized. This enzyme required Mg2+ for activity, maximum activity being observed at 5 and 20 mM Mg2+ with AMP and ATP, respectively, as substrates. Of the divalent cations tested, Mn2+ and Co2+ were able to replace Mg2+ partially, whereas Ca2+ was ineffective. Zinc strongly inhibited the enzyme activity and Ni2+ caused partial inhibition. This enzyme required Cl- for activity, the optimal concentration being 20 mM or more. The order of effectiveness of anions was Cl- greater than Br- greater than I- approximately NO3-. Sulfate and acetate were ineffective. The optimal pH was 8.0. The activity of the purified enzyme was stimulated by the addition of lipid to the assay mixture. This enzyme hydrolyzed all 5'-nucleotides tested, but did not hydrolyze 3'-nucleotides or ribose 5-phosphate. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme appeared to be a single polypeptide, with a molecular weight of 72 kDa.

5'-Nucleotidase↗