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Y Terada

Publications and source records attributed to Y Terada.

At least 73 records · Page 4Linked to original sources
PubMed2000

Discovery of a New Pulsating X-Ray Source with a 1549.1 Second Period, AX J183220-0840.

A new pulsating X-ray source, AX J183220-0840, with a 1549.1 s period was discovered at R.A.=18h32m20s and decl.=-8&j0;40'30" (J2000, with an uncertainty of 0&farcm;6) during an ASCA observation on the Galactic plane. The source was observed two times, in 1997 and in 1999. A phase-averaged X-ray flux of 1.1x10-11 ergs cm-2 s-1 and a pulsation period of 1549.1+/-0.4 s were consistently obtained from these two observations. The X-ray spectrum was represented by a flat, absorbed power law with a photon index of Gamma approximately 0.8 and an absorption column density of NH approximately 1.3x1022 cm-2. Also, a signature of iron K-shell line emission with a centroid of 6.7 keV and an equivalent width of approximately 450 eV was detected. From the pulsation period and the iron-line feature, AX J183220-0840 is likely to be a magnetic white dwarf binary with a complexly absorbed thermal spectrum with a temperature of about 10 keV.

Journal Article↗
PubMed2000

Crystal structure of amylomaltase from thermus aquaticus, a glycosyltransferase catalysing the production of large cyclic glucans.

Amylomaltase is involved in the metabolism of starch, one of the most important polysaccharides in nature. A unique feature of amylomaltase is its ability to catalyze the formation of cyclic amylose. In contrast to the well studied cyclodextrin glucanotransferases (CGTases), which synthesize cycloamylose with a ring size (degree of polymerization or DP) of 6-8, the amylomaltase from Thermus aquaticus produces cycloamyloses with a DP of 22 and higher. The crystal structure of amylomaltase from Thermus aquaticus was determined to 2.0 A resolution. It is a member of the alpha-amylase superfamily of enzymes, whose core structure consists of a (beta, alpha)(8) barrel. In amylomaltase, the 8-fold symmetry of this barrel is disrupted by several insertions between the barrel strands. The largest insertions are between the third and fifth barrel strands, where two insertions form subdomain B1, as well as between the second and third barrel strands, forming the alpha-helical subdomain B2. Whereas part of subdomain B1 is also present in other enzyme structures of the alpha-amylase superfamily, subdomain B2 is unique to amylomaltase. Remarkably, the C-terminal domain C, which is present in all related enzymes of the alpha-amylase family, is missing in amylomaltase. Amylomaltase shows a similar arrangement of the catalytic side-chains (two Asp residues and one Glu residue) as in previously characterized members of the alpha-amylase superfamily, indicating similar mechanisms of the glycosyl transfer reaction. In amylomaltase, a conserved loop of around eight amino acid residues is partially shielding the active center. This loop, which is well conserved among other amylomaltases, may sterically hinder the formation of small cyclic products.

Amino Acid Sequence↗
PubMed2000

Microfilament stabilization by jasplakinolide arrests oocyte maturation, cortical granule exocytosis, sperm incorporation cone resorption, and cell-cycle progression, but not DNA replication, during fertilization in mice.

Jasplakinolide (JAS), which induces microfilament polymerization and stabilization, inhibits microfilament-mediated events in murine oocyte maturation and fertilization in a fashion unlike the effects of cytochalasin B (CCB) and latranculin A (LAT A). JAS prevents egg polar body emission at a much lower concentration than either CCB or LAT A. Microfilament bundles were detected on the entire egg cortex after JAS exposure. Conversely, microfilament patterns did not change after exposure to CCB, and few microfilaments were observed after exposure to LAT A. Eggs that were allowed to recover from JAS were unable to recover normal microfilament organization. During oocyte maturation, JAS prevented both spindle migration to the oocyte cortex and first polar body emission. During in vitro fertilization, sperm head entered the eggs and formed pronuclei, but sperm tail entry, pronuclear centration, and second polar body emission were not detected. DNA synthesis occurs in these JAS-treated zygotes. JAS inhibited not only the formation, but also the disassembly, of incorporation cones. JAS was also found to prevent cortical granule exocytosis following artificial activation, and cortical granules were still beneath the plasma membrane even after activation. Finally, incorporation of microinjected nonmuscle actin into the microfilament network of mice eggs was delayed by JAS. We conclude that JAS acts as a microfilament inhibitor during maturation and fertilization and is more powerful than other inhibitors. Its mechanism differs in that it promotes assembly and stabilization of microfilaments. JAS is a novel cell permeable tool for the investigation of microfilament-dependent events in early mammalian development.

Actin Cytoskeleton↗
PubMed2000

Right ventricular volume unloading evaluated by tangential magnetocardiography.

OBJECTIVE: The evaluation of right ventricular volume overload in the presence of a right bundle branch block based solely on the results of an electrocardiogram is difficult. The purpose of this study was to purify acute right ventricular volume unloading from the tangential magnetocardiography. METHODS: We measured the tangential (x-y plane) magnetocardiogram and electrocardiogram simultaneously in nine patients with a secundum atrial septal defect. The magnetocardiograms were obtained before surgical closure and during the immediate postoperative period using the 32-channel superconducting quantum interference device system in a magnetically shielded room. RESULTS: The QRS duration on the surface electrocardiogram decreased significantly (p < 0.05) in the immediate postoperative period. The right ventricular depolarization time as measured by the magnetocardiogram was shortened from 40.3 +/- 6.1 to 25.3 +/- 7.4 milliseconds (p < 0.0005). The maximum peak amplitude during right ventricular depolarization decreased from 17.9 +/- 4.8 to 11.1 +/- 4.9 pT (p < 0.01). CONCLUSIONS: We conclude that acute volume unloading of the right ventricle was indicated quantitatively by shortening of the right ventricular depolarization time and a reduction in the amplitude of current vectors originating from the right ventricular depolarization on the tangential magnetocardiography.

Adolescent↗
PubMed2000

Extended septoplasty for subaortic stenosis developed 19 years after double-outlet right ventricle repair.

A 27-year-old woman developed subaortic stenosis 19 years after double-outlet right ventricle repair. Subaortic stenosis was caused by a narrow ring of fibromuscular ridge associated with a bulge of the underlying septal muscle. The aortic valve was bicuspid and stenotic. We conducted extended septoplasty, replacing the aortic valve. Postoperative cineangiogram showed an adequate left ventricular outflow pathway. Double-outlet right ventricle repair may thus be followed by subaortic stenosis as long as 19 years after initial surgery. This lesion was assumed due to acquired disease secondary to flow disturbances in the left ventricular outflow, so reconstructing an adequate outflow pathway is effective and appears to help avoid recurring stenosis.

Adult↗
PubMed2000

Atypical decondensation of the sperm nucleus, delayed replication of the male genome, and sex chromosome positioning following intracytoplasmic human sperm injection (ICSI) into golden hamster eggs: does ICSI itself introduce chromosomal anomalies?

OBJECTIVE: To examine nuclear decondensation, positioning of sex chromosomes, and the S-phase in human sperm nuclei following intracytoplasmic sperm injection (ICSI) into hamster eggs. DESIGN: Prospective analysis of hamster eggs and human sperm following ICSI. SETTING: Division of Reproductive Sciences, Oregon Health Sciences University and Oregon Regional Primate Research Center. PATIENT(S): Fertile donor sperm from a commercial source. INTERVENTION(S): Human sperm were examined by immunofluorescence stain, bromodioxyuridine (BrdU) uptake assay and fluorescence in situ hybridization following ICSI into hamster eggs. MAIN OUTCOME MEASURE(S): Immunostaining and fluorescence in situ hybridization. RESULT(S): Decondensation of human sperm nuclei occurred initially in the basal region, and perinuclear theca of sperm persisted around the condensed apical region. In some sperm nuclei, following ICSI the sex chromosomes were in the apical region, remaining condensed for longer than in the basal region. S-phase entry of human sperm nuclei following ICSI was delayed compared to the zona-free hamster egg penetration assay. CONCLUSION(S): These results force questions about the mechanism of male pronuclear formation after ICSI and suggest new strategies for understanding the basis of chromosomal anomalies leading to birth defects as well as continuing improvements in the safety and efficacy of infertility therapies.

Animals↗
PubMed2000

An iso-integral mapping technique using magnetocardiogram, and its possible use for diagnosis of ischemic heart disease.

We have developed an iso-integral mapping technique that uses magneto-cardiogram (MCG) data to obtain a map as projected total current image on the torso from the heart. We have also investigated the applicability of iso-integral mapping to the diagnosis of ischemic heart disease. We simulated and measured the characteristics of two types of iso-integral maps: one using tangential (Bxy) components, and one using the normal component (Bz). Each vector component was measured by two types of superconducting quantum interference device (SQUID) system to determine the tangential and normal components. The tangential component of the magnetic field appeared to be equivalent to the current image in the myocardium projected on the observing plane, and we were able to obtain a projected total current image by integration of the tangential components during the depolarization and repolarization processes. And we found that the iso-integral maps of normal hearts showed similar pattern in both processes; however, those of ischemic hearts showed different patterns.

Action Potentials↗
PubMed2000

Study on masticatory movement and its ability: efficacy of a test capsule in the evaluation of masticatory movement.

It has been shown that a test capsule originally designed as a simple and reliable aid to evaluate masticatory ability could help to identify the characteristics of chewing loops between individuals in evaluation of masticatory movement, and detect even a slight disorder in the stomatognathic system. In this study, the Sirognathograph(R) Analysing System was used to record and analyse mandibular movement with the test capsule and seven foods. In terms of total examination of the chewing rhythm, the test capsule showed a higher SX/SY ratio of chewing cycle duration (SX: variance between individuals, SY: variance between chewing loops of each person) than those of the comparative foods, excluding chewing gum. The coefficient of variation of the test capsule in the dimensions of the chewing path was lower than those of the comparative foods. Reverse and crossover patterns in chewing gum have been frequently observed in subjects with craniomandibular disorders. Subjects with a low frequency of such patterns in chewing gum tended to have a low frequency with the test capsule as well. Those with a high frequency in chewing gum tended to show such patterns with the test capsule more frequently.

Adult↗
PubMed2000

X-ray structure of acarbose bound to amylomaltase from Thermus aquaticus. Implications for the synthesis of large cyclic glucans.

As a member of the alpha-amylase superfamily of enzymes, amylomaltase catalyzes either the transglycosylation from one alpha-1,4 glucan to another or an intramolecular cyclization. The latter reaction is typical for cyclodextrin glucanotransferases. In contrast to these enzymes, amylomaltase catalyzes the formation of cyclic glucans with a degree of polymerization larger than 22. To characterize the factors that determine the size of the synthesized cycloamyloses, we have analyzed the X-ray structure of amylomaltase from Thermus aquaticus in complex with the inhibitor acarbose, a maltotetraose derivative, at 1.9 A resolution. Two acarbose molecules are bound to the enzyme, one in the active site groove at subsite -3 to +1 and a second one approximately 14 A away from the nonreducing end of the acarbose bound to the catalytic site. The inhibitor bound to the catalytic site occupies subsites -3 to +1. Unlike the situation in other enzymes of the alpha-amylase family, the inhibitor is not processed and the inhibitory cyclitol ring of acarbose, which mimicks the half chair conformation of the transition state, does not bind to catalytic subsite -1. The minimum ring size of cycloamyloses produced by this enzyme is proposed to be determined by the distance of the specific substrate binding sites at the active site and near Tyr54 and by the size of the 460s loop. The 250s loop might be involved in binding of the substrate at the reducing end of the scissile bond.

Acarbose↗
PubMed2000

Leiomyosarcoma of the pulmonary vein.

A case of a 74-year-old man with leiomyosarcoma of the pulmonary vein is reported. The patient felt transient chest oppression while playing golf 1 week before he visited a clinic with a common cold. He underwent an ultrasonographic examination of the heart, which showed a mass lesion in the left atrium. The preoperative clinical diagnosis was myxoma of the left atrium. Cardiac surgery revealed the mass to be a leiomyosarcoma, probably extending from the left inferior pulmonary vein. The patient underwent a left lower lobectomy of the lung, and the tumor was confirmed to have originated from the wall of the left inferior pulmonary vein. Although the patient had a metastatic lesion in the right axillary lymph node 11 months later, which was excised, he remained free of disease 14 months after the initial operation. Histologically, the tumors were composed of pleomorphic cells with bizarre nuclei and spindle cells with blunt-ended nuclei with 1-4 mitotic figures in 10 high power fields. Immunohistologically, the tumor cells were positive for alpha-smooth muscle actin and desmin. We reviewed 17 cases of leiomyosarcoma of the pulmonary vein (six males and 11 females with a mean age of 50 years in each group). The present case was the oldest in age and to our knowledge was the first reported case with metastasis in a distant lymph node.

Aged↗
PubMed2000

Activated STAT1 suppresses proliferation of cultured rat mesangial cells.

BACKGROUND: JAK-STAT signaling has been shown to promote development and proliferation in lymphopoietic and hematopoietic lineages. We investigated the effect of activated STAT1 on mesangial cell proliferation. METHODS: Rat mesangial cells of primary culture (rMCs) were used in the following experiments: (1) Whole cell lysates were immunoblotted against JAK1 and JAK2. (2) Whole cell lysates and nuclear proteins were extracted from rMCs with or without treatment with interferon-gamma, and immunoblotting was performed against both STAT1 and tyrosine (701)-phosphorylated STAT1. (3) rMCs and rMCs electroporated with either wild-type STAT1, mutated STAT1, or antibody against STAT1 were incubated with interferon-gamma for 20 hours, followed by a further incubation with [3H]-thymidine for four hours. RESULTS: JAK1, JAK2, and STAT1 were detected in whole cell lysates, suggesting that JAK-STAT signaling could be activated by interferon-gamma (INF-gamma). Using an antibody specific for tyrosine-phosphorylated STAT1, we detected signal in the INF-gamma-treated nuclear extracts, which showed translocation of phosphorylated STAT1 to the nucleus. [3H]-thymidine incorporation in the presence of INF-gamma was significantly lower than that of control in a dose-dependent manner. The introduction of wild-type STAT1 enhanced the effect of interferon-gamma and decreased [3H]-thymidine incorporation, whereas tyrosine-mutated (Y701F) STAT1 and SH2 domain (R602T)-mutated STAT1 reversed INF-gamma-induced suppression of [3H]-thymidine incorporation. Electroinjected antibody against STAT1 increased [3H]-thymidine incorporation upon stimulation with INF-gamma. CONCLUSION: STAT1 activated by interferon-gamma suppresses mesangial cell proliferation.

Animals↗
PubMed2000

Sperm aster formation and pronuclear decondensation during rabbit fertilization and development of a functional assay for human sperm.

Microtubule organization and chromatin configurations in rabbit eggs after in vivo rabbit fertilization and after intracytoplasmic injection with human sperm were characterized. In unfertilized eggs, an anastral barrel-shaped meiotic spindle, oriented radially to the cortex, was observed. After rabbit sperm incorporation, microtubules were organized into a radial aster from the sperm head, and cytoplasmic microtubules were organized around the male and female pronuclei. The microtubules extending from the decondensed sperm head participated in pronuclear migration, and organization around the female pronucleus may also be important for pronuclear centration. Support for these observations was found in parthenogenetically activated eggs, in which microtubule arrays were organized around the single female pronucleus that formed after artificial activation. These observations support a biparental centrosomal contribution during rabbit fertilization as opposed to a strictly paternal inheritance pattern suggested from previous studies. In rabbit eggs that received injected human donor sperm, an astral array of microtubules radiated from the sperm neck and enlarged as the sperm head underwent pronuclear decondensation. gamma-Tubulin was observed in the center of the sperm aster. We conclude that the rabbit egg exhibits a blended centrosomal contribution necessary for completion of fertilization and that the rabbit egg may be a novel animal model for assessing centrosomal function in human sperm and spermatogenic cells following intracytoplasmic injection.

Animals↗
PubMed2000

Structure-specificity relationship of cardiac glycosides as a substrate for glucohydrolase II.

Cardenolide glucohydrolase II (CGH II) is a cardenolide-specific glucohydrolase obtained from Digitalis lanata leaves. We investigated the structure-specificity relationship of several cardenolide disaccharides as a substrate for CGH II. Conformation analysis of the substrates was performed using molecular mechanics calculations. The sugar chain conformation of two inert glycosides was significantly different from that of the other glycosides. The other two glycosides, which were weak substrates of CGH II, were suggested to have an intramolecular hydrogen bond between the sugar groups. It was deduced that this hydrogen bond restricts the conformational change of the sugar chain and prevents the glycosides from enzymatic recognition.

Carbohydrates↗
PubMed2000

Successful use of argon plasma coagulation and tranilast to treat granulation tissue obstructing the airway after tracheal anastomosis.

We successfully used argon plasma coagulation (APC) and tranilast to treat granulation tissue that had formed on an end-to-end tracheal anastomosis. APC had several advantages over laser in the management of exuberant granulation tissue, and we considered tranilast to be effective in our patient. To our knowledge, this is the first description of the use of APC in the management of anastomotic granulation tissue in the trachea or bronchus.

Adult↗
PubMed2000

The effects of alcoholic compounds on the stability of type I collagen studied by differential scanning calorimetry.

The interaction between bovine tendon collagen and a series of homologous alcohols were investigated using a differential scanning calorimetry. For all alcoholic substances, as well as 2-hydroxyethyl methacrylate (HEMA), the concentration dependence of the denaturation temperature of collagen was observed, which showed a minimum at 30%. Clearly there are two opposing actions on the stabilization of the collagen structure; destabilization dominates over stabilization at lower concentrations, and vice versa at higher concentrations. The concentration dependence became greater for longer chain alcohols, while it was suppressed by the increased number of OH groups. The chain length-dependent surface tension may be related, which controls the permeation of the additives through the collagen fibers. Overall hydrophobicity, indicated by the hydrophile-lipophile balance (HLB) numbers, suggests the importance of the hydrophobic effect in the interaction of collagen and alcoholic substances, including adhesive monomers such as HEMA.

Alcohols↗
PubMed2000

Influence of different elastic moduli of dowel and core on stress distribution in root.

This study was carried out to investigate the influences of elastic moduli of the dowel-core combination on the stress distribution in the root by the use of 2-dimensional finite element analysis. The peak stress at the dowel-cement interface was influenced strongly by a change of elastic modulus of the post (from 20,000 kg/mm2 as a hard prefabricated post to 8,000 kg/mm2 as a custom cast post) for both vertical and 45 degree oblique loading (rho > 90%). Peak dentinal stress adjacent to the luting cement layer depended only on the post material for vertical loading (rho [symbol: see text] 99%). In contrast, the post and core materials (from 8,000 kg/mm2 as cast core to 300 kg/mm2 as composite resin core) acted in cooperation on the stress magnitude for oblique loading, but the influence of the core material was stronger than that of the post (rho of core [symbol: see text] 41% and rho of post [symbol: see text] 26%). On the other hand, at the marginal region the effect of the core material contributed more than 86% to the peak stress value for both loadings, and the post material affected at most about 11% of the bending resistance.

Algorithms↗