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M Noma

Publications and source records attributed to M Noma.

At least 55 records · Page 3Linked to original sources
PubMed1994

Improved crystals of the toxic protein MAP by protein engineering towards the host specificity.

Mirabilis anti-viral protein (MAP) is a ribosome-inactivating protein from Mirabilis jalapa L. Since MAP is effective over a broad spectrum of species, the protein is difficult to express in heterologous hosts such as Escherichia coli. Recently, we obtained a MAP mutant, Y72F which exhibits a lower (1/100) activity against E. coli ribosomes while retaining almost full activity against mammalian cells [Habuka, Miyano, Kataoka, Tsuge & Noma (1992). J. Biol. Chem. 267, 7758-7760]. For the crystallographic studies, the Y72F MAP expression vector with an OmpA leading sequence was constructed and expressed in E. coli. The Y72F MAP mutant was then isolated and purified from the cell culture medium. Crystals were grown using the crystallization conditions for the native MAP crystals [Miyano et al. (1992). J. Mol. Biol. 226, 281-283]: 50% ammonium sulfate containing 50 mM ammonium citrate and 2 mM adenine sulfate, pH 5.4. The crystals belong to space group P3(1)21 (or P3(2)21) with a = b = 104.1 and c = 134.3 A. The crystals are isomorphous with the wild-type crystals but diffract to higher resolution. Imaging-plate photographs of the Y72F mutant showed sharp intense spots without the streaking observed in the native crystals.

Journal Article↗
PubMed1994

Interfacial kinetic reaction of human 5-lipoxygenase.

The kinetics of human 5-lipoxygenase were investigated in the presence of Tween 20 using a continuous spectrophotometric assay. Using the mixture at a constant molar ratio of arachidonate/Tween 20 at pH 8.0, the steady-state velocity on a varied arachidonate concentration did not follow simple Michaelis-Menten-type kinetics and double-reciprocal plot analysis gave hyperbolic curves. However, by introducing the concept of a local pH change, it was possible to analyze the kinetics as simple Michaelis-Menten type. The concept of a local pH change implies that when utilizing an acidic and amphiphilic substance as a substrate, such as arachidonate, the medium around the substrate is acidified with an increased concentration of substrate. This concept was explained rationally by two experiments. Consequently, the data were transformed according to a local pH change and analyzed according to a dual phospholipid model as has been proposed for phospholipase A2 [Hendrickson, H. S. and Dennis, E. A. (1984) Kinetic analysis of the dual phospholipid model for phosphalipase A2, J. Biol. Chem. 259, 5734-5739]. It is concluded that 5-lipoxygenase performs an interfacial reaction in the arachidonate/Tween 20 mixed micelles in the same manner as phospholipase A2. The values of Km were almost constant (about 0.07 molar fraction), even when arachidonate molar ratios were changed in the surface of the mixed micelles. The values for Ks (the association constant of the enzyme to the micelle interface) ranged over 0.21-0.48 microM. The Vmax was 25.76 mumol.min-1.mg-1. This concept of a local pH change could be used extensively with enzymes which utilize both amphiphilic and acidic substances as substrates.

Arachidonate 5-Lipoxygenase↗
PubMed1994

Crystallization and preliminary X-ray crystallographic studies of recombinant human leukotriene A4 hydrolase complexed with bestatin.

Recombinant human leukotriene A4 hydrolase complexed with bestatin, an inhibitor of metalloprotease, has been crystallized by the hanging drop vapor diffusion method using 0.1 M phosphate buffer (pH 6.5) and 50 to 54% saturated ammonium sulfate. The orthorhombic crystals belong to the space group I222 or I2(1)2(1)2(1) with unit cell dimensions of a = 273.6 A, b = 261.3 A and c = 52.9 A. They diffract beyond 2.5 A resolution and a native data set up to 3 A resolution has been collected on an imaging plate Weissenberg camera using synchrotron radiation.

Amino Acid Sequence↗
PubMed1994

Sequence analysis of the agaB gene encoding a new beta-agarase from Vibrio sp. strain JT0107.

An agarase gene (agaB) was cloned from genomic DNA of Vibrio sp. strain JT0107. Analysis of the 3200 nucleotide sequence just before the agarase 0107 gene (agaA) which existed in genomic DNA of Vibrio sp. strain JT0107 revealed a putative single open reading frame coding for 955 amino acids. Comparison of the deduced amino acid sequence of AgaB to that of agarase 0107 revealed the existence of partially highly homologous regions. A part of this gene was expressed in Escherichia coli to yield a protein with agarase activity. This is the first report of evidence by genetic analysis that at least two different kinds of agarases exist in strain JT0107.

Amino Acid Sequence↗
PubMed1994

Effects of continuous intravenous infusion of isosorbide dinitrate on development of tolerance to vasodilating action in human epicardial coronary arteries.

This study was performed to determine the effects of long-term intravenous infusion on the coronary vasodilating actions of continuous intravenous and bolus intracoronary administration of isosorbide dinitrate (ISDN). With quantitative coronary angiography, the coronary diameter and the vasodilating response to intracoronary ISDN (1 mg) at angiographically normal segments were studied before and after intravenous administration of ISDN, 10 to 60 micrograms/min for 1 hour, 2 days, or 5 days. The vasodilating effects of intravenous ISDN were 72% +/- 13%, 65% +/- 21%, and 6% +/- 11% of the response to intracoronary ISDN in the baseline study in each group. Irrespective of the duration of intravenous infusion, subsequent intracoronary ISDN dilated coronary arteries to extent similar to that observed in each baseline study. In conclusion, significant coronary vasodilating effects of intravenous ISDN were observed after a 2-day infusion, whereas tolerance to the vasodilating effects apparently developed within 5 days of infusion. The vasodilating response to bolus intracoronary ISDN was preserved even when the vasodilating effects of intravenous ISDN were no longer present.

Angina Pectoris↗
PubMed1994

Purification and characterization of a novel enzyme, alpha-neoagarooligosaccharide hydrolase (alpha-NAOS hydrolase), from a marine bacterium, Vibrio sp. strain JT0107.

A novel enzyme, alpha-neoagarooligosaccharide hydrolase (EC 3.2.1.-), which hydrolyzes the alpha-1,3 linkage of neoagarooligosaccharides to yield agaropentaose (O-beta-D-galactopyranosyl(1-->4)-O-3,6-anhydro-alpha-L-galactopyranosyl (1-->3)-D-galactose], agarotriose [O-beta-D-galactopyranosyl(1-->4)-O-3,6-anhydro- alpha-L-galactopyranosyl (1-->3)-D-galactose], agarobiose [O-beta-D-galactopyranosyl(1-->4)-3,6-anhydro-L-galactose], 3,6-anhydro-L-galactose, and D-galactose was isolated from the marine bacterium Vibrio sp. strain JT0107 and characterized. This enzyme was purified 383-fold from cultured cells by using a combination of ammonium sulfate precipitation, successive anion-exchange column chromatography, gel filtration, and hydroxyapatite chromatography, gel filtration, and hydroxyapatite chromatography. The purified protein gave a single band (M(r), 42,000) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Estimation of the M(r) by the gel filtration method gave a value of 84,000, indicating that the enzyme is dimeric. Amino acid sequence analysis revealed it to have a single N-terminal sequence that has no sequence homology to any other known agarases. The optimum temperature and pH were 30 degrees C and 7.7, respectively. The Km and maximum rate of metabolism for neoagarobiose were 5.37 mM and 92 U/mg of protein, respectively.

Amino Acid Sequence↗
PubMed1994

Collateral development induced by repetitive brief coronary occlusion relates to the functional state of pre-existing collaterals.

The effects of pre-existing collaterals (PC) and the perfusion size (PS) on the ischemia-induced collateral development were studied in a canine model. Under aseptic conditions, the dogs were instrumented with pairs of ultrasonic crystals to measure regional wall motion in the territory of the left circumflex (LCX) and left anterior descending coronary artery. A micromanometer was used to measure left ventricular (LV) pressure. Two to 3 weeks after surgery, 2 min coronary occlusion (CO) of LCX was repeated every 32 min consecutively day and night using a remote control, motor-driven hydraulic cuff occluder. Regional wall motion and LV pressure were monitored via a telemetry system in 23 dogs. The functional state of PC was estimated by the level of % reduction of regional wall motion at the end of the first 2 min CO, which ranged from -11 to -141%. PS of LCX area at risk determined by the post mortem angiograms ranged from 35 to 54% (mean +/- SEM; 44 +/- 1%) of LV. Number of CO needed for collateral development ranged from 8 to 628, and was exponentially related to the functional state of PC (r = -0.77, n = 23, p < 0.01), but not to PS (r = 0.43, n = 19, p = 0.07). These results suggest that the functional maturity of pre-existing collaterals is one of the major determinants of collateral development related to ischemic stimuli.

Animals↗
PubMed1994

Prevalence and pathogenesis of silent myocardial ischemia following myocardial infarction.

The objective of this study was to examine the prevalence and pathogenesis of silent myocardial ischemia during exercise following myocardial infarction. Exercise-induced myocardial ischemia was assessed by 201Tl-SPECT (single photon emission computed tomography) 4.5 weeks after acute myocardial infarction in 229 patients. Exercise-induced myocardial ischemia occurred in 109 patients (48%), and 72 (32%) had silent ischemia. Although the prevalence of multivessel coronary artery disease was similar between patients with silent and symptomatic ischemia, the size of reversible myocardial ischemia was larger in patients with symptomatic ischemia than in those with silent ischemia (21.3 +/- 3.0% vs 13.2 +/- 1.9% of LV, p < 0.05). The incidence of reversible ischemia remote from the infarct area was higher in patients with symptomatic ischemia than in those with silent ischemia (30% vs 17%, p < 0.10). The cause of silent ischemia after myocardial infarction may be closely related to the smaller size of reversible myocardial ischemia. Ischemia remote from, or adjacent to, the infarct area could be a factor in determining the presence or absence of pain.

Coronary Angiography↗
PubMed1994

Isolation of human CD34+ peripheral blood stem cells using an immunomagnetic positive selection system: prior monocyte depletion using a nylon-wool column.

An immunomagnetic separation system has been used to collect CD34+ cells in mobilized blood after treatment with a nylon-wool column. Cell purities were increased from 2.6% preseparation to 94.6% postseparation, with a mean yield 45.2% (n = 4). Forty percent of CD34+ cells separated by the immunomagnetic procedure formed colonies in the presence of hematopoietic growth factors in a limiting dilution assay. Eleven percent of these clones proliferated to over 10(5) cells and contained megakaryocytes.

Antigens, CD↗
PubMed1993

Inhibitory effects of 3-nitrophloroglucinecarboxylic acid derivatives on Epstein-Barr virus early antigen induction.

The inhibitory effects of two series of 3-nitrophloroglucinecarboxylic acid derivatives, 3-nitro-2,4,6-trihydroxythiobenzamides (II) and 3-nitro-phloroglucinecarboxylates (III), on Epstein-Barr virus early antigen (EBV-EA) induction were examined using Raji cells. Some of them strongly inhibited the induction, N-nonyl and O-decyl derivatives being the most potent inhibitors among the thioamides and esters, respectively. These results suggest the possibility that these two 3-nitrophloroglucinecarboxylic acid derivatives may be listed as novel inhibitors of tumor promotion.

Antigens, Viral↗
PubMed1993

Nucleotide sequence of a genomic gene encoding tritin, a ribosome-inactivating protein from Triticum aestivum.

A genomic gene of tritin, a ribosome-inactivating protein (RIP) from Triticum aestivum, was cloned using a barley RIP gene as a probe. The 5'-non-coding region has potential TATA boxes and three sequences homologous to the binding sequence of the transcriptional activator protein Opaque-2 which activates maize RIP gene expression. The cloned DNA encoded tritin consists of 275 amino acids with no secretion signal sequence. The coding region of tritin was expressed in Escherichia coli using lac promoter and yielded a protein similar to the native one, as determined by SDS-polyacrylamide gel electrophoresis and immunological analysis.

Amino Acid Sequence↗
PubMed1993

Cloning and sequencing of agaA, a unique agarase 0107 gene from a marine bacterium, Vibrio sp. strain JT0107.

An agarase gene (agaA) was cloned from genomic DNA of Vibrio sp. strain JT0107. An open reading frame of 2,985 nucleotides gave a primary translation product composed of the mature protein, agarase 0107 (975 amino acid residues, with a molecular weight of 105,271) and a signal peptide of 20 amino acid residues at the N terminus. Comparison of the deduced amino acid sequence of agarase 0107 with those of Streptomyces coelicolor and Pseudomonas atlantica suggests that these enzymes share two regions in common. The AgaA protein which was expressed in Escherichia coli had the agarase activity. Agarase 0107 hydrolyzes not only agarose but also neoagarotetraose [O-3,6-anhydro-alpha-L-galactopyranosyl (1-->3)-O-beta-D-galactopyranosyl(1-->4)-O-3,6-anhydro-alpha-L-galact opy ranosyl (1-->3)-D-galactose] to yield neoagarobiose [O-3,6-anhydro-alpha-L-galactopyranosyl(1-->3)-D-galactose]. This is a quite unique characteristic for a beta-agarase.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of a new agarase from a marine bacterium, Vibrio sp. strain JT0107.

A marine bacterial strain that decomposes the cell walls of some seaweeds, including a Laminaria sp. and Undaria pinnatifida, has been isolated from seawater. This strain has been classified to the genus Vibrio. One of the enzymes which the bacteria secreted into the culture medium was isolated and purified 45-fold from the culture fluid by a combination of ammonium sulfate precipitation and successive rounds of anion-exchange column chromatography. Purified protein migrated as a single band (M(r), 107,000) on sodium dodecyl sulfate-polyacrylamide gels. By amino acid sequence analysis, it was determined that this protein had a single N-terminal sequence that did not exhibit identity with the sequences of other agarases from marine bacteria. This novel enzyme was found to be an endo-type beta-agarase (EC 3.2.1.81) which hydrolyzes the beta-1,4 linkage of agarose to yield neoagarotetraose [O-3,6-anhydro-alpha-L-galactopyranosyl (1-->3)-O-beta-D-galactopyranosyl(1-->4)-O-3,6-anhydro-alpha-L-galactopy ranosyl (1-->3)-D-galactose] and neoagarobiose [O-3,6-anhydro-alpha-L-galactopyranosyl (1-->3)-D-galactose] at a pH of around 8. The optimum temperature was 30 degrees C. This enzyme did not decompose sodium alginate or lambda-, iota-, or kappa-carrageenan. This enzyme may be of practical application in gene technology in the isolation of DNA fragments from agarose gels after electrophoresis.

Amino Acid Sequence↗
PubMed1993

Isolated coronary ostial stenosis in Takayasu's arteritis: case report and review of the literature.

This report describes a rare clinical course of a young Japanese woman with Takayasu's arteritis and a review of the literature. Her first symptom was angina pectoris due to isolated left coronary ostial stenosis, which was relieved by aortocoronary bypass grafting surgery using a saphenous vein graft. At that time, the C-reactive protein was negative and the histopathologic findings of the specimens of the aorta could not confirm aortitis. Although she was free from any cardiovascular symptoms for about fifteen years, syncopal attacks occurred owing to severe stenosis of the major branches of the aortic arch revealed by intravenous digital subtraction arteriograms. Thus, Takayasu's arteritis could be a cause of coronary ostial stenosis in young women even if the inflammatory findings are negative and the major branches of the aortic arch are not involved at operation. In addition, revascularization using internal thoracic arteries might possess a potential risk of coronary insufficiency due to a later involvement of these proximal arteries.

Adult↗
PubMed1993

Recurrent forearm thrombophlebitis after transvenous permanent pacemaker insertion.

This report describes a 69-year-old Japanese woman with bilateral forearm thrombophlebitis that developed soon after transvenous permanent pacemaker insertion. Intravenous administration of urokinase and heparin rapidly resolved fever, painful forearm swelling and inflammatory findings. Digital subtraction venograms revealed a brachiocephalic vein thrombosis. A ten-month treatment with warfarin and ticlopidine resulted in the complete restoration of venous flow. Although thrombophlebitis associated with transvenous permanent pacemaker insertion has a relatively low incidence (0.3%), prompt diagnosis and treatment with anticoagulant and/or thrombolytic agents are important for the late clinical outcome in cases with deep venous thrombosis.

Aged↗
PubMed1992

Endotoxin transduces Ca2+ signaling via platelet-activating factor receptor.

Lipopolysaccharide (LPS) is a pathogenic substance causing severe multiple organ failures and high mortality. Although several LPS binding proteins have been identified, the molecular mechanism underlying the LPS signaling pathway still remains obscure. We have found that the LPS-induced Ca2+ increase in platelets and platelet aggregation is blocked by selective platelet-activating factor (PAF) receptor antagonists, thus suggesting a cross-talk between LPS and the PAF receptor. Next, we confirmed this hypothesis using the cloned PAF receptors [(1991) Nature 349, 342-346; (1991) J. Biol. Chem. 266, 20400-20405] expressed in Xenopus oocytes and Chinese hamster ovary (CHO) cells. In both systems, cells responded to LPS only when PAF receptors were expressed, and specific PAF binding was successfully displaced and reversibly dissociated by LPS. PAF receptor activation by LPS may represent a novel important pathway in the pathogenesis of circulatory collapse and systemic thrombosis caused by endotoxin.

Animals↗