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Biomedical subjects

Y Kakuta

Publications and source records attributed to Y Kakuta.

At least 19 recordsLinked to original sources

Influence of residual carbon on the decomposition process of PCDD/Fs in MSWI fly ash.

In heating treatment of fly ash to reduce PCDD/Fs, cooling process is important to inhibit de novo formation of PCDD/Fs. In this study, assuming that residual carbon is the dominant factor of de novo synthesis, the relation between PCDD/Fs and residual carbon was examined. Firstly, by using MSWI fly ash which was treated in an actually operated facility, both the content of PCDD/Fs and residual carbon were decreased as heating temperature increased. At temperatures higher than 400 degrees C, the reduction rate of residual carbon was higher than 20% and more than 95% of PCDD/Fs was decomposed. In order to simulate a heating treatment process, fly ash was heated at different temperatures and gas atmospheres, oxygen or nitrogen. Heated fly ash was placed for 2 h at 300 degrees C in oxygen to promote de novo synthesis, or cooled immediately. As a result, good correlation between PCDD/Fs and residual carbon was found, therefore it was shown experimentally that residual carbon was the main factor for PCDD/Fs formation by de novo synthesis in fly ash.

Atmosphere↗

Resident's concerns and attitudes towards Solid Waste Management facilities.

Because of limited space, the siting and construction of a new SWM facility is a big challenge in Japan. An SWM facility should be socially accepted as well as environmentally and economically sound. This study aimed to investigate people's concerns about SWM facilities and their attitudes towards such facilities. A questionnaire was designed based on literature reviews and was sent to residents in three municipalities with different backgrounds. The questions covered concerns on the impact of an SWM facility, management aspects, unfairness of facility siting, and attitudes to facility construction. Of the many concerns, "pollution and health effect" had the highest rating, followed by "reliability", "damage to nature" and "cost". The rating was different between municipalities, reflecting their geographic and social backgrounds. Using factor analysis, correlations among concerns were analyzed, and five principal components were extracted, namely "pollution", "nuisance", "facility management", "planning of facility", and "merit/demerit". Although obvious correlations were not found between individual items of concern and attitudes to construction of a facility, the discriminant analysis indicated dominant concerns of attitudes, but the disagreement between actual impact and citizens were found. As for attributes, the "opposed" attitude decreased for residents who had visited an SWM facility, even if they had only seen it from outside.

Cities↗

Heparan sulphate N-sulphotransferase activity: reaction mechanism and substrate recognition.

Human heparan sulphate N-deacetylase/N-sulphotransferase 1 sulphates the NH(3) (+) group of the glucosamine moiety of the heparan chain in heparan sulphate/heparin biosynthesis. An open cleft that runs perpendicular to the sulphate donor 3'-phosphoadenosine 5'-phosphosulphate may constitute the acceptor substrate-binding site of the sulphotransferase domain (hNST1) [Kakuta, Sueyoshi, Negishi and Pedersen (1999) J. Biol. Chem. 274, 10673-10676]. When a hexasaccharide model chain is docked into the active site, only a trisaccharide (-IdoA-GlcN-IdoA-) portion interacts directly with the cleft residues: Trp-713, His-716 and His-720 from alpha helix 6, and Phe-640, Glu-641, Glu-642, Gln-644 and Asn-647 from random coil (residues 640-647). Mutation of these residues either abolishes or greatly reduces hNST1 activity. Glu-642 may play the critical role of catalytic base in the sulphuryl group transfer reaction, as indicated by its hydrogen-bonding distance to the NH(3) (+) group of the glucosamine moiety in the model and by mutational data.

Animals↗

Overexpression, purification and characterization of RecJ protein from Thermus thermophilus HB8 and its core domain.

A recJ homolog was cloned from the extremely thermophilic bacterium Thermus themophilus HB8. It encodes a 527 amino acid protein that has 33% identity to Escherichia coli RecJ protein and includes the characteristic motifs conserved among RecJ homologs. Although T.thermophilus RecJ protein (ttRecJ) was expressed as an inclusion body, it was purified in soluble form through denaturation with urea and subsequent refolding steps. Limited proteolysis showed that ttRecJ has a protease-resistant core domain, which includes all the conserved motifs. We constructed a truncated ttRecJ gene that corresponds to the core domain (cd-ttRecJ). cd-ttRecJ was overexpressed in soluble form and purified. ttRecJ and cd-ttRecJ were stable up to 60 degrees C. Size exclusion chromatography indicated that ttRecJ exists in several oligomeric states, whereas cd-ttRecJ is monomeric in solution. Both proteins have 5'-->3' exonuclease activity, which was enhanced by increasing the temperature to 50 degrees C. Mg(2+), Mn(2+) or Co(2+) ions were required to activate both proteins, whereas Ca(2+) and Zn(2+) had no effects.

Amino Acid Motifs↗

Crystal structure of Escherichia coli Fdx, an adrenodoxin-type ferredoxin involved in the assembly of iron-sulfur clusters.

Escherichia coli ferredoxin (Fdx) is an adrenodoxin-type [2Fe-2S] ferredoxin. Recent genetic analyses show that it has an essential role in the maturation of various iron-sulfur (Fe-S) proteins. Fdx probably functions as a component of the complex machinery responsible for the biogenesis of Fe-S clusters. Its crystal structure was determined by the multiple-wavelength anomalous dispersion method using the iron atoms in the [2Fe-2S] cluster of the protein and then refined to R and R(free) values of 0.255 and 0.278, respectively, at 1.7 A resolution. The structure of Fdx is similar to the structures of bovine adrenodoxin (Adx) and Pseudomonas putida putidaredoxin (Pdx) whose respective root-mean-square deviations of the corresponding Calpha atoms are 1.8 and 2.2 A. This analysis also revealed the structure of the C-terminal residues protruding into the solvent, which is missing in Adx and Pdx. The [2Fe-2S] cluster is located at the edge of the molecule and bonds with the Sgamma atoms of Cys42, Cys48, Cys51, and Cys87. Electrostatic potential analysis showed that the surface of Fdx has two negatively charged areas separated by a hydrophobic lane. One is conserved on the surface of Adx which is an area of interaction with adrenodoxin reductase. Cys46 is located on the molecular surface in the vicinity of the [2Fe-2S] cluster, an indication that it may be involved in Fe-S cluster formation.

Adrenodoxin↗

Structure and function of sulfotransferases.

Sulfotransferases (STs) catalyze the transfer reaction of the sulfate group from the ubiquitous donor 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to an acceptor group of numerous substrates. This reaction, often referred to as sulfuryl transfer, sulfation, or sulfonation, is widely observed from bacteria to humans and plays a key role in various biological processes such as cell communication, growth and development, and defense. The cytosolic STs sulfate small molecules such as steroids, bioamines, and therapeutic drugs, while the Golgi-membrane counterparts sulfate large molecules including glucosaminylglycans and proteins. We have now solved the X-ray crystal structures of four cytosolic and one membrane ST. All five STs are globular proteins composed of a single alpha/beta domain with the characteristic five-stranded beta-sheet. The beta-sheet constitutes the core of the Paps-binding and catalytic sites. Structural analysis of the PAPS-, PAP-, substrate-, and/or orthovanadate (VO(3-)(4))-bound enzymes has also revealed the common molecular mechanism of the transfer reaction catalyzed by sulfotransferses. The X-ray crystal structures have opened a new era for the study of sulfotransferases.

Binding Sites↗

Impact of coronary artery remodeling on clinical presentation of coronary artery disease: an intravascular ultrasound study.

OBJECTIVES: We examined the association between the features of the culprit lesion in coronary artery disease (CAD) and clinical presentation as shown by intravascular ultrasound (IVUS). BACKGROUND: The association between coronary remodeling pattern and clinical presentation of CAD is unclear. METHODS: We analyzed 125 selected patients who underwent preintervention IVUS. Acute myocardial infarction (AMI) and unstable angina pectoris (UAP) were categorized as an acute coronary syndrome (ACS), and stable angina pectoris (SAP) and old myocardial infarction (OMI) as stable CAD. Coronary remodeling patterns and plaque morphology of the culprit lesion obtained by IVUS were analyzed in terms of their association with clinical presentation or angiographic morphology. RESULTS: Angiographically complex lesions were associated with ACS and OMI. In patients with a complex lesion, positive remodeling was observed more frequently than in those with a simple lesion. In AMI and UAP, positive remodeling was observed more frequently than in SAP and OMI (82% vs. 78% vs. 33% vs. 40%, respectively, p < 0.0001). The remodeling ratio was greater in AMI and UAP than in SAP and OMI (1.26 +/- 0.15 vs. 1.11 +/- 0.10 vs. 0.94 +/- 0.11 vs. 0.96 +/- 0.13, respectively, p < 0.0001). Furthermore, within ACS, the remodeling ratio was greater in AMI than in UAP (1.26 +/- 0.15 vs. 1.11 +/- 0.10, respectively, p < 0.05), whereas the frequency of positive remodeling was not different. CONCLUSIONS: Positive remodeling was more frequently observed in ACS than in stable CAD. Moreover, the degree of positive remodeling was greater in AMI than in UAP. These results may reflect the impact of remodeling types and its degree in the culprit lesion of CAD on clinical presentation.

Adult↗

1-Aminocyclopropane-1-carboxylate synthase of Penicillium citrinum: primary structure and expression in Escherichia coli and Saccharomyces cerevisiae.

A plant hormone, ethylene, is formed through 1-aminocyclopropane-1-carboxylic acid (ACC). A fungus, Penicillium citrinum, was found to synthesize ACC and to degrade ACC into 2-oxobutyrate and ammonia. ACC synthase, responsible for ACC synthesis in P. citrinum, was characterized on the molecular level by sequencing of N terminal and proteolytic peptides of the enzyme, and cloning and sequencing of its cDNA. The ACC synthase from P. citrinum had 430 amino acid residues and a shorter C terminal than the plant enzyme. The enzyme purified from Escherichia coli transformed with ACC-synthase-encoding DNA showed similar properties to those of the purified enzyme from P. citrinum. Saccharomyces cerevisiae with ACC synthase accumulated ACC in the medium with increasing time of incubation. The sequence of ACC synthase from P. citrinum was compared with that of the plant enzyme with discussion about important residues for catalysis.

Amino Acid Sequence↗

[A case of bronchogenic cyst which developed from negative findings to a thin-walled cavity for about 6 years].

A 56-year-old man whose chest radiograph in 1993 was normal was referred to our hospital because of a productive cough in 1997. Chest radiographs showed a thin-walled cavity filled with air. We followed his condition radiographically for three years and observed enlargement of the diameter of the lesion and appearance of an air fluid level, and we therefore decided to perform thoracoscopic middle lobe resection in 1999. Histological examination showed a communication between the cavity and a bronchus. As far as we know, there are no previous reports about intrapulmonary bronchogenic cysts which on radiographic observation developed from negative findings to a thin-walled cavity filled with air over a 6-year period.

Bronchogenic Cyst↗

[Spinal cord sarcoidosis without abnormal shadows on chest radiography or chest CT diagnosed by transbronchial lung biopsy].

The patient was a woman aged 56 years. In February 1998, she complained of fatigability of the right upper limb and disturbed extension of the right fourth finger. Because her condition deteriorated gradually and myelopathic signs such as difficulty in walking developed, she was hospitalized in May 1999 for close examination and appropriate treatment; and she was a few days later transferred to our hospital because of progressive myelopathy. In T2-weighted MR images of the cervical spine, the high-intensity area ranged between C2 and Th1, and in Gd-DTPA enhanced MRI the high-intensity area was seen between C3 and C7. Although chest radiographs and chest CT scans were normal, spinal cord sarcoidosis could not be ruled out, and therefore, bronchoscopic examination was performed. Specimens obtained from transbronchial lung biopsy (TBLB) revealed non-caseating epithelioid cell granulomas, and so and the disease was diagnosed as spinal cord sarcoidosis. Both symptoms and MRI findings were improved by treatment with corticosteroids. It is suggested that, in patients suspected of spinal cord sarcoidosis from MRI findings. TBLB should be aggressively attempted, even if chest radiographs and chest CT scans are normal.

Biopsy↗

Crystal structure of rat heme oxygenase-1 in complex with heme.

Heme oxygenase catalyzes the oxidative cleavage of protoheme to biliverdin, the first step of heme metabolism utilizing O(2) and NADPH. We determined the crystal structures of rat heme oxygenase-1 (HO-1)-heme and selenomethionyl HO-1-heme complexes. Heme is sandwiched between two helices with the delta-meso edge of the heme being exposed to the surface. Gly143N forms a hydrogen bond to the distal ligand of heme, OH(-). The distance between Gly143N and the ligand is shorter than that in the human HO-1-heme complex. This difference may be related to a pH-dependent change of the distal ligand of heme. Flexibility of the distal helix may control the stability of the coordination of the distal ligand to heme iron. The possible role of Gly143 in the heme oxygenase reaction is discussed.

Animals↗

Structure-function modeling of the interactions of N-alkyl-N-hydroxyanilines with rat hepatic aryl sulfotransferase IV.

Although previous investigations have clearly shown that N-hydroxy arylamines and N-hydroxy heterocyclic amines are substrates for sulfotransferases, relatively little is known about which structural features of the N-hydroxy arylamines are important for sulfation to occur. The purpose of this investigation was to determine the extent to which secondary N-alkyl-N-hydroxy arylamines interact with aryl sulfotransferase (AST) IV (also known as tyrosine-ester sulfotransferase or ST1A1) and to evaluate these interactions using molecular modeling techniques. AST IV is a major cytosolic sulfotransferase in the rat, and it catalyzes the sulfation of various phenols, benzylic alcohols, arylhydroxamic acids, oximes, and primary N-hydroxy arylamines. In this study, three secondary N-hydroxy arylamines, N-hydroxy-N-methylaniline, N-ethyl-N-hydroxyaniline, and N-hydroxy-N-n-propylaniline, were found to be substrates for the purified rat hepatic AST IV. However, when the N-alkyl substituent was an n-butyl group (i.e., N-n-butyl-N-hydroxyaniline), the interaction with the enzyme changed from that of a substrate to competitive inhibition. This change in specificity was further explored through the construction and use of a model for AST IV based on mouse estrogen sulfotransferase, an enzyme whose crystal structure has been previously determined to high resolution. Molecular modeling techniques were used to dock each of the above N-hydroxy arylamines into the active site of the homology model of AST IV and determine optimum ligand geometries. The results of these experiments indicated that steric constraints on the orientation of binding of secondary N-alkyl-N-hydroxy arylamines at the active site of AST IV play a significant role in determining the nature of the interaction of the enzyme with these compounds.

Aminophenols↗

Characterization of platelet-activating factor-induced cytosolic calcium mobilization in human eosinophils.

BACKGROUND: Activated eosinophils play an important role in the pathogenesis of bronchial asthma and other allergic diseases, and platelet-activating factor (PAF) is a potent activator of eosinophils. OBJECTIVE: To characterize the cytosolic Ca2+ ([Ca2+]i) mobilization in human eosinophils in response to PAF. METHODS: [Ca2+]i responses to PAF were examined in human eosinophils using a microscopic fura-2 fluorescence-ratio imaging system. RESULTS: PAF caused a significant and dose-dependent increase in (Ca2+)i, which consisted of an initial rapid rise followed by a sustained elevation. This PAF-induced (Ca2+)i rise was inhibited by WEB 2086, a specific PAF receptor antagonist. The addition of 5 mM EGTA or 1 mM Ni2+ to a nominally Ca2+-free solution did not appreciably reduce the initial rise but significantly inhibited the sustained rise. The application of a protein kinase C inhibitor, Ro31-8220, augmented the sustained increase by PAF. Thapsigargin, a microsomal Ca2+ ATPase inhibitor, induced no appreciable change in a nominally Ca2+-free solution but induced a marked increase in (Ca2+)i when changed to a Ca2+-containing solution. CONCLUSIONS: The initial rapid rise and the following sustained rise in (Ca2+)i by PAF depends on Ca2+ release from the intracellular Ca2+ stores and Ca2+ influx, respectively, which are regulated by protein kinase C in human eosinophils. Furthermore, the so called Ca2+-capacitative entry is possibly involved in the Ca2+ influx from the extracellular solution in human eosinophils.

Calcium Signaling↗

Neutrophilia associated with anaplastic carcinoma of the thyroid: production of macrophage colony-stimulating factor (M-CSF) and interleukin-6.

Cancers associated with marked neutrophilia are relatively rare. We report here two cases of anaplastic thyroid carcinoma associated with neutrophilia. We measured the concentrations of granulocyte colony-stimulating factor (G-CSF), macrophage CSF (M-CSF), granulocyte-macrophage CSF (GM-CSF), interleukin-1alpha (IL-1alpha), IL-1beta, IL-6, and tumor necrosis factor-alpha (TNF-alpha) in sera, pleural effusion, cyst fluid of the thyroid carcinoma region, or culture supernatants of carcinoma cells. Maximum levels of elevated white blood cell counts reached 106.1 x 10(9)/L (neutrophils 103.0 x 10(9)/L) in case 1 and 62.3 x 10(9)/L (neutrophils 57.9 x 10(9)/L) in case 2. Acute-phase reactants were elevated to various degrees, and hypercalcemia was found in both cases. IL-6, G-CSF, and M-CSF seemed to play the principal roles in neutrophilia in case 1, and the elevated levels of IL-6 and M-CSF seemed to mainly contribute to neutrophilia in case 2. Immunohistochemical staining revealed that carcinoma cells themselves produce IL-6 regardless of the types of carcinoma cells. To our knowledge, this is the first report describing the contribution of M-CSF to neutrophilia in patients with thyroid carcinoma.

Adenocarcinoma, Papillary↗

Crystal structure of human catecholamine sulfotransferase.

Sulfonation, like phosphorylation, can modify the activity of a variety of biological molecules. The sulfotransferase enzymes sulfonate neurotransmitters, drugs, steroid hormones, dietary carcinogens and proteins. SULT1A3 specifically sulfonates catecholamines such as dopamine, adrenaline and noradrenaline. The crystal structure of SULT1A3 with a sulfate bound at the active site, has been determined at 2.4 A resolution. Although the core alpha/beta fold is like that of estrogen and heparan sulfotransferases, major differences occur in and around the active site. Most notably, several regions surrounding the active site, including a section of 40 residues, are disordered in SULT1A3. Regions that are topologically equivalent to the disordered parts of SULT1A3 are involved in substrate and cofactor binding in estrogen and heparan sulfotransferase. Flexibility in these regions suggests that ligand binding elicits a disorder-order transition in and around the active site of sulfotransferases and might contribute to the broad substrate specificity of these enzymes.

Amino Acid Sequence↗

Substrate gating confers steroid specificity to estrogen sulfotransferase.

Estrogen sulfotransferase (EST) exhibits a high substrate specificity and catalytic efficiency toward estrogens such as estradiol (E2) but insignificant ability to sulfate hydroxysteroids such as dehydroepiandrosterone (DHEA). To provide the structural basis for this estrogen specificity, we mutated amino acid residues that constitute the substrate-binding site of EST. Among these mutants, only Tyr-81 decreased E2 and increased DHEA sulfotransferase activities. Substitution for Tyr-81 by smaller hydrophobic residues increased K(m(E2)) for E2 activity, whereas the k(cat(E2)) remained relatively constant. The Y81L mutant exhibited the same DHEA activity as wild-type hydroxysteroid sulfotransferase, for which K(m(DHEA)) remained relatively constant, and k(cat(DHEA)) was markedly increased. The side chain of Tyr-81 is directed at the A-ring of the E2 molecule in the substrate-binding pocket of EST, constituting a steric gate with Phe-142 sandwiching E2 from the opposite side. The present mutagenesis study indicates that the 3beta-hydroxyl group of the DHEA molecule is excluded from the catalytic site of EST through steric hindrance of Tyr-81 with the C-19 methyl group of DHEA. Thus, this stricture-like gating caused by steric hindrance appears to be a structural principle for conferring estrogen specificity to EST.

Dehydroepiandrosterone↗

Crystal structure of the sulfotransferase domain of human heparan sulfate N-deacetylase/ N-sulfotransferase 1.

Heparan sulfate N-deacetylase/N-sulfotransferase (HSNST) catalyzes the first and obligatory step in the biosynthesis of heparan sulfates and heparin. The crystal structure of the sulfotransferase domain (NST1) of human HSNST-1 has been determined at 2.3-A resolution in a binary complex with 3'-phosphoadenosine 5'-phosphate (PAP). NST1 is approximately spherical with an open cleft, and consists of a single alpha/beta fold with a central five-stranded parallel beta-sheet and a three-stranded anti-parallel beta-sheet bearing an interstrand disulfide bond. The structural regions alpha1, alpha6, beta1, beta7, 5'-phosphosulfate binding loop (between beta1 and alpha1), and a random coil (between beta8 and alpha13) constitute the PAP binding site of NST1. The alpha6 and random coil (between beta2 and alpha2), which form an open cleft near the 5'-phosphate of the PAP molecule, may provide interactions for substrate binding. The conserved residue Lys-614 is in position to form a hydrogen bond with the bridge oxygen of the 5'-phosphate.

Amidohydrolases↗