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K Maruta

Publications and source records attributed to K Maruta.

At least 55 records · Page 3Linked to original sources
PubMed1995

Purification and properties of a novel enzyme, maltooligosyl trehalose synthase, from Arthrobacter sp. Q36.

Arthrobacter sp. Q36 produces a novel enzyme, maltooligosyl trehalose synthase, which catalyzes the conversion of maltooligosaccharide into the non-reducing saccharide, maltooligosyl trehalose (alpha-maltooligosyl alpha-D-glucoside) by intramolecular transglycosylation. The enzyme was purified from a cell-free extract to an electrophoretically homogeneous state by successive column chromatography on Sepabeads FP-DA13, DEAE-Sephadex A-50, Ultrogel AcA44, and Butyl-Toyopearl 650M. The enzyme was specific for maltooligosaccharides except maltose, and catalyzed the conversion to form maltooligosyl trehalose. The Km of the enzyme for maltotetraose, maltopentaose, maltohexaose, and maltoheptaose were 22.9 mM, 8.7 mM, 1.4 mM, and 0.9 mM, respectively. The enzyme had a molecular mass of 81,000 by SDS-polyacrylamide gel electrophoresis and a pI of 4.1 by gel isoelectrofocusing. The N-terminal and C-terminal amino acids of the enzyme were methionine and serine, respectively. The enzyme showed the highest activity at pH 7.0 and 40 degrees C, and was stable from pH 6.0 to 9.5 and up to 40 degrees C. The enzyme activity was inhibited by Hg2+ and Cu2+.

Amino Acid Sequence↗
PubMed1995

Purification and characterization of a novel enzyme, maltooligosyl trehalose trehalohydrolase, from Arthrobacter sp. Q36.

A novel enzyme, maltooligosyl trehalose trehalohydrolase from Arthrobacter sp. Q36 was purified from a cell-free extract to an electrophoretically pure state by successive column chromatography on Sepabeads FP-DA13, Butyl-Toyopearl 650M, DEAE-Toyopearl 650S, and Toyopearl HW-55S. The enzyme specifically catalyzed the hydrolysis of the alpha-1,4-glucosidic linkage that bound the maltooligosyl and trehalose moieties of maltooligosyl trehalose. The Km of the enzyme for maltosyl trehalose, maltotriosyl trehalose, maltotetraosyl trehalose, and maltopentaosyl trehalose was 5.5 mM, 4.6 mM, 7.0 mM, and 4.2 mM, respectively. The enzyme had a molecular mass of 62,000 by SDS-polyacrylamide gel electrophoresis and a pI of 4.1 by gel isoelectrofocusing. The N-terminal amino acid of the enzyme was threonine. The enzyme showed the highest activity at pH 6.5 and 45 degrees C, and was stable from pH 5.0 to 10.0 and up to 45 degrees C. The activity was inhibited by Hg2+, Cu2+, Fe2+, and Zn2+.

Amino Acid Sequence↗
PubMed1993

Calcification inhibitors in human ligamentum flavum.

To examine the presence of substances which inhibit calcification in human ligamentum flavum, the inhibitory effect of an Na2HPO4 extract of the flavum was determined in terms of the in vitro calcium uptake of the ligamentum flavum matrix. Additionally, grafts of extracted and non-extracted dry ligamentum flavum matrices were transplanted into the dorsal muscles of rats, and calcification in the grafts was examined radiologically and histochemically. In order to determine if component cells of human ligamentum flavum produce calcification inhibitors, ligamentum flavum cells were cultured, and the crystal inhibitor activity of the culture medium was measured by a seed test which used hydroxyapatite as the nucleus of precipitation. The calcification reaction system demonstrated that the ligamentum flavum extract contains an inhibitory factor for calcium uptake by the ligamentum flavum matrix. The seed test revealed that human ligamentum flavum cells produce calcification inhibitor activity.

Adolescent↗
PubMed1993

[A form of dopa-responsive dystonia of late onset with diurnal fluctuations].

We report a case of a 67-year-old woman who had dopa-responsive dystonia of late onset with diurnal fluctuations. She was well until the age of 65 years, when she noted the insidious onset of involuntary movements mainly involving the neck and trunk. She had no family history of movement disorders and had never received neuroleptics. Two years after her symptoms began, she visited our clinic. Neurological examination revealed slow repetitive extension and flexion movements of the neck and trunk, and irregular slow movements involving the mouth, tongue and limbs. The cranial nerves, cerebellar function, muscle strength, deep reflexes and sensory function were intact. Clinically and electromyographically, dystonia was characteristic of her involuntary movements. No parkinsonian features were present. The involuntary movements showed diurnal fluctuations that improved after sleep and the administration of L-DOPA and trihexyphenidyl. Dopamine receptor blocking agents aggravated her condition. Routine blood chemistry including copper metabolism, cerebrospinal fluid findings, and brain CT scan were all normal. Dopa-responsive dystonia is characterized by onset in childhood or adolescence and is frequently associated with parkinsonian features. Our patient had non-hereditary neck and trunk dystonia of late onset that responded to L-DOPA. Her disorder may constitute a specific form of dopa-responsive dystonia.

Age Factors↗
PubMed1991

Effects of ethane-1-hydroxy-1, 1-diphosphonate on cell differentiation, and proteoglycan and calcium metabolism, in the proximal tibia of young rats.

The effects of ethane-1-hydroxy-1, 1-diphosphonate(EHDP) on cell differentiation, and on the metabolism of proteoglycan and calcium in the epiphyseal plate and metaphysis of rats were investigated through histology and autoradiograms of [35S]-sulfate, 45Ca, and [3H]-thymidine. Suppression of bone resorption in the metaphysis due to low dose EHDP administration was associated with a proliferation of osteoclasts with an increased number of nuclei. High dose EHDP induced enlargement of the hypertrophic zone of the epiphyseal plate and suppression of calcification of the cartilage matrix. This change had a significant association not only with the suppression of chondroitin sulfate synthesis and the degradation in the cartilage matrix, but also with the suppression of growth and differentiation of chondrocytes. Calcification was also inhibited in the metaphysis, and growth and differentiation from undifferentiated mesenchymal cells to osteoblasts, osteocytes, and osteoclasts were also suppressed by high dose EHDP.

Animals↗
PubMed1990

Effects of radical scavengers on the development of experimental diabetes.

The possible value of radical scavengers in the prevention of beta cell destruction was studied in two animal models of type I diabetes. Eight compounds were tested alone or in combinations. In the low-dose streptozotocin model treatment started 24 hr after the last injection of the beta cell toxin, in the BB rat daily administration was started at 50 days of age (i.e., 20-70 days before diabetes onset). No effect was seen in the low-dose streptozotocin model for 3-aminobenzamide, N-acetyl-DL-homocysteine thiolactone, ebselen, and butylated hydroxyanisole whereas partial suppression of hyperglycaemia was seen in mice receiving cysteamine. In BB rats diabetes development was delayed and partially suppressed by administration of ebselen plus vitamin E plus MaxEPA (fish lipid concentrate), but not when ebselen was replaced by nicotinamide. We conclude that the disease process is not readily modifiable by treatment with exogenous radical scavengers.

Aging↗
PubMed1989

Augmentation by external Mg ions of beta-adrenoceptor-mediated actions in the longitudinal muscle of rat uterus.

1. The longitudinal muscle isolated from the uterus of oestrogen-treated rats was not spontaneously active in Locke solution, and electrical stimulation evoked phasic contraction. Isoprenaline (3 x 10(-11) - 10(-8) M) and dibutyryl cyclic AMP (db cyclic AMP, 0.1-0.8 mM) depressed the phasic contraction; the depression was enhanced in the presence of 0.6 mM Mg. 2. The contracture generated by 40 mM K was partially relaxed by isoprenaline (10(-11) - 10(-8) M) and db cyclic AMP (0.1-0.8 mM). Mg (0.6 mM) enhanced the isoprenaline-induced relaxation, but not that induced by db cyclic AMP. 3. The membrane potential of the muscle was -61 mV, and electrical stimulation induced an action potential which consisted of spike and plateau components. Application of isoprenaline and db cyclic AMP mainly reduced the duration of the plateau potential. The effect was potentiated by 0.6 mM Mg. 4. The membrane was hyperpolarized, accompanied by a decrease in membrane resistance, when 10(-8) M isoprenaline or 0.8 mM db cyclic AMP was applied. The effects of isoprenaline were prominently augmented in the presence of 1.2 mM Mg, while those of db cyclic AMP were slightly potentiated. 5. Forskolin (0.1 microM) or papaverine (10 microM) inhibited the phasic contraction and the K-contracture. The effect on the phasic contraction was potentiated by 0.6 mM Mg, while that on the K-contracture was not affected. 6. Forskolin shortened the action potential at 0.3 microM, and hyperpolarized the membrane with a decrease in membrane resistance at 3.0 microM. The membrane effects were augmented by 0.6 and 1.2 mM Mg, respectively. 7. It was hypothesized that external Mg ions could affect at least two processes involved in actions at beta-adrenoceptors on rat myometrium; receptor-agonist interaction and cyclic AMP-mediated inhibition of membrane excitability.

Animals↗
PubMed1989

Comparison of Mg, Mn, and Co ions affecting the beta-adrenoceptor-mediated membrane response in the guinea-pig taenia caeci.

Electrical activity was recorded intracellularly from the muscle cell of guinea-pig taenia caeci in Locke solution. Membrane potential was -46.4 mV, and spike potentials were discharged spontaneously. Isoprenaline (3 microM) hyperpolarized the membrane and suppressed the spike discharge. The hyperpolarization by isoprenaline was increased at low K (2 mM), while decreased at high K (11.8, 29.5, 59 mM). The hyperpolarization by isoprenaline was potentiated in the presence of external Mg ions, depending on the concentration of Mg (0-9.6 mM). Forskolin (3 microM) and papaverine (30 microM) hyperpolarized the membrane; the effects were augmented by 1.2 mM Mg. The hyperpolarization in response to 3 microM isoprenaline or 100 microM papaverine was inhibited by Mn, Co, and low Ca (1 mM) whereas it was not affected by high Ca (7.5 mM). Verapamil (0.5, 2 microM) had no influence of the hyperpolarization caused by isoprenaline. It was discussed that extracellular and/or intracellular Mg and Ca ions played important roles in the beta-adrenoceptor-mediated action on the smooth muscle membrane of taenia caeci.

Animals↗
PubMed1989

Modulation of arachidonic acid metabolism has limited effects on the development of type I diabetes in animal models.

The therapeutic potential of modulators of arachidonic acid metabolism was probed in two animal models of type I (insulin-dependent) diabetes. Sulphasalazine treatment (50 and 400 mg/kg) did not affect diabetes development in the low dose streptozotocin model in male CD-1 mice nor in diabetes prone BB/WorD rats (100 mg/kg). Administration of acetyl salicylic acid (50 mg/kg) or BW755C (60 mg/kg) caused partial suppression of hyperglycaemia in male C57BL/6 mice after low dose streptozotocin. Twice daily treatment of BB rats with acetyl salicylic acid (5 mg/kg) did not significantly alter the course of diabetes development. We conclude that modulation of arachidonic acid metabolism has limited effects on immune-mediated diabetes.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1989

Prospective analysis of eosinophilia in spontaneously diabetic BB rats: correlation with islet inflammation but not with diabetes development.

A prospective analysis of eosinophil counts in diabetes prone BB rats showed that eosinophilia (greater than 5%) occurred between 70-100 days of age. The presence of eosinophilia did not predict diabetes onset because persistently normoglycaemic animals developed eosinophilia as well. Nevertheless a correlation with the disease process in BB rats was found. Eosinophilia decreases a few weeks after diabetes onset but persists in non diabetic rats. Histological analyzes showed that eosinophilia correlates with eosinophil infiltration of islets (p less than 0.005) and the latter correlates with severe insulitis (p less than 0.005). These findings indicate that eosinophilia is associated with a late stage of islet inflammation in diabetes prone BB rats independent of whether the animals develop diabetes or not.

Animals↗
PubMed1989

Simple, sensitive assay of polyamines by high-performance liquid chromatography with electrochemical detection after post-column reaction with immobilized polyamine oxidase.

This simple, rapid liquid-chromatographic assay of urinary polyamines (putrescine, spermidine, spermine, and cadaverine) involves electrochemical detection with a post-column immobilized enzyme, polyamine oxidase (EC 1.4.3.6) from soybean seedlings. Polyamines are separated by isocratic ion-pairing reversed-phase chromatography, then enzymatically converted, with release of hydrogen peroxide, via the post-column reactor with immobilized polyamine oxidase; the hydrogen peroxide is detected by electrochemical oxidation on a platinum electrode. The detection limits for injected putrescine, spermidine, and spermine were 0.3, 0.5, 0.6, and 4 pmol, respectively, with linear ranges of two to three orders of magnitude. Reproducibility was also good, with CV values less than 7%. The efficiency of the immobilized enzyme column was not decreased after analysis of 300 urine samples. Putrescine and spermidine excretion in urine from patients with blood cancers and solid cancers was significantly increased.

Biogenic Polyamines↗
PubMed1988

Postpartum changes in the mechanical responses of the circular muscle of rat uterus.

The circular muscle strips were isolated from rat uterus 10-60 h after parturition, and the electrical and mechanical responses were investigated. The muscle strips exhibited a variety of contractile activity ranging from frequent spontaneous contractions generated on an elevated muscle tone to a sustained contracture, when incubated with Mg-free Krebs solution. The muscle tone was lowered, and phasic contractions were abolished when the external Ca was removed. Muscle tone was also lowered by addition of 1.2 mM Mg, 1 mM spermidine, or 1 mM tetracaine. The membrane potential was about -25 mV in a muscle which exhibited a contracture, and the membrane was hyperpolarized by 20-25 mV by the (1.5-4.5 x 10(-5) M) caused a gradual decrease in muscle tone, and the that Ca-influx was increased, for which prostaglandin(s) was membrane was hyperpolarized. In view of the above results, it is hypothesized that Ca-influx was increased, for which prostaglandin(s) was probably responsible, in the circular muscle of postpartum rat uterus, thereby elevating the muscle tone in Mg-free solution.

Animals↗
PubMed1988

Effects of cytochalasins on the mechanical and membrane responses in the isolated longitudinal myometrium of pregnant rat with reference to the EGTA-resistant contraction.

Effects of cytochalasins B and D (CB, CD) were examined for the contractions of the longitudinal myometrium of pregnant rat exposed to Krebs solution, 40 mM K Krebs, and Ca-free (40 mM K) solution containing 5 mM Mg. The Ca-free contraction was evoked by applying 3 mM ATP. Application of CB caused a prompt inhibition of the contractions: 3 microM CB depressed the twitch contraction generated in Krebs solution by 12%, the K-contracture by 6%, and the ATP-induced contraction in the Ca-free solution by 59%. CD (3 microM) depressed the K-contracture by 31%, and the ATP-induced contraction in the Ca-free solution by 81%. CB and CD in 3 microM hyperpolarized the membrane and depressed the generation of action potential. From the above results, it was discussed that depressant effects of cytochalasins on twitch contractions in Krebs solution are at least in part due to the depression of membrane excitability, whereas contractions evoked in high K solutions are depressed by cytochalasins due to their effects on cytoskeleton.

Adenosine↗
PubMed1988

IL-1 and IFN-gamma increase vascular permeability.

We examined the effect of cytokines on vascular permeability in vivo. Wistar rats received intradermal injections of various cytokine preparations and the permeability index (delta PI) was calculated from the difference between the absorption values of cytokine- and vehicle-treated skin sections after the extraction of accumulated Evans blue vital dye. Injections of a mixture of recombinant interleukin-1 alpha and beta (Il-1 alpha, IL-1 beta) and interferon-gamma (IFN-gamma) caused a maximal increase of permeability after 30 min (delta PI = 2). The administration of single recombinant cytokines revealed that the increase of permeability is mainly due to the action of IL-1 beta (delta PI = 1.4) and IFN-gamma (delta PI = 2.9) (P less than 0.001) at doses of 1-20 microU per injection site. IL-1 alpha slightly increased vascular permeability, whereas recombinant IL-2 and recombinant tumour necrosis factor alpha had no significant effects. Histological observations revealed significantly increased numbers of degranulated mast cells in skin sections pretreated with IL-1 beta (P less than 0.005) or IFN-gamma (P less than 0.001). The cytokine-mediated rise of vascular permeability could be suppressed by pretreatment of the animals with the vasoactive amine antagonizing drugs methysergide, pizotifen and cyproheptadine. Our experiments indicate an important role of IL-1 beta and IFN-gamma as vasoactive substances besides their function as hormone-like messengers between leucocytes.

Animals↗
PubMed1988

Simultaneous determination of catecholamines and serotonin by liquid chromatography, after treatment with boric acid gel.

We describe a liquid-chromatographic method for simultaneously determining norepinephrine, epinephrine, dopamine, and serotonin in 0.5 mL of human plasma. These analytes are purified on boric acid gel from Aldrich, separated on a reversed-phase C18 column, and detected electrochemically at +600 mV. Absolute recoveries of internal standards were 84% for 3,4-dihydroxybenzylamine and 57% for N-methylserotonin. Reproducibility was good to excellent, depending on the concentration of the analytes. A chromatographic run is complete in 40 min, but this can be shortened by about half when the determination of only serotonin is required, by increasing the column temperature from 40 degrees C to 60 degrees C.

Adult↗
PubMed1987

Diabetogenic action of streptozotocin: essential role of membrane permeability.

A single high dose of streptozotocin was found to cause a transient increase in islet capillary permeability 2-4 h after administration. Staining of areas of increased vascular permeability by Evans blue showed that islets, but not exocrine tissue, were affected. The permeability increase seems to involve vasoactive substances released by mast cells. A mast cell inhibitor (disodium cromoglycate) and a serotonin antagonist (methysergide) were found protective. Furthermore, administration of methysergide partially prevented the development of hyperglycaemia in streptozotocin-treated rats. In mice, almost full protection from diabetes development was reached by both methysergide and disodium cromoglycate. Our observations indicate an important role of mast cell controlled membrane permeability in this model of beta-cell destruction and diabetes development.

Animals↗