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Biomedical subjects

Y Maeno

Publications and source records attributed to Y Maeno.

At least 55 records · Page 3Linked to original sources
PubMed2002

Detection of cardiomyocyte apoptosis in forensic autopsy cases.

The purpose of the present study was to determine reliable parameters for the detection of apoptotic cells for use as a diagnostic marker during the early stage of acute myocardial infarction (AMI) in forensic autopsy cases. Myocardial tissues taken from forensic autopsy cases were examined by immunohistochemical and molecular-biological methods using the terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end-labelling (TUNEL) and the DNA laddering methods. In cases of AMI with a time period between 2 h from onset to death and 20 h post-mortem time, the nuclei of cardiomyocytes were stained positive with the TUNEL method and DNA fragmentation of myocardial cells was detected by agarose gel electrophoresis. Similar findings were obtained in cases of carbon monoxide (CO) intoxication. However, no apoptotic cells were found in other cases such as methamphetamine (MAP) intoxication, tetrodotoxin intoxication, alcohol intoxication, asphyxia, head injury, heart injury or myocarditis. These findings suggested that it would be possible to apply TUNEL-positive cells as a diagnostic marker during the early stages of AMI.

Adult↗
PubMed2002

Quantitative evaluation of the changes in plasma concentrations of cardiac natriuretic peptide before and after transcatheter closure of atrial septal defect.

UNLABELLED: The purpose of this study was to investigate the changes in plasma concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in patients with atrial septal defect (ASD) during transcatheter closure of defects. The plasma concentrations of ANP and BNP were obtained from 14 patients with ASD at before closure, and at 5 min, 24 h, 1 mo and 3 mo after transcatheter ASD closure using an Amplatzer septal occluder. Ten healthy children aged 6-18 y were studied as controls. All ASDs were successfully closed. Compared with control values (mean +/- SD, 17 +/- 6.8 ng 1(-1), ANP concentrations before closure were significantly elevated (24 +/- 9.8ng 1(-1), p < 0.05). ANP concentrations increased significantly at 5 min after closure (34 +/- 18 ng 1(-1), p < 0.05) compared with preclosure concentrations. At 24 h after closure, the concentrations decreased to values not different from control values (19 +/- 11 ng 1(-1), p = ns). BNP levels before closure (19 +/- 9.9 ng 1(-1) were also elevated significantly compared with control values (12 +/- 4.9ng 1(-1), p < 0.05). BNP concentrations increased significantly at 5 min after closure (23 +/- 14 ng 1(-1), p < 0.05) compared with preclosure concentrations. ANP values at 24 h were lower than at 5 min after closure, whereas BNP values were higher (32 +/- 11 ng 1(-1), p < 0.05). As with ANP, the concentrations gradually decreased to values not different from control values at 3 mo after the procedure (12 +/- 6.3 ng 1(-1), p = ns). CONCLUSION: Plasma concentrations of ANP and BNP may become effective markers for evaluating changes in cardiac load after transcatheter ASD closure.

Adolescent↗
PubMed2001

Magnetic field-tuned quantum criticality in the metallic ruthenate Sr3Ru2O7.

The concept of quantum criticality is proving to be central to attempts to understand the physics of strongly correlated electrons. Here, we argue that observations on the itinerant metamagnet Sr3Ru2O7 represent good evidence for a new class of quantum critical point, arising when the critical end point terminating a line of first-order transitions is depressed toward zero temperature. This is of interest both in its own right and because of the convenience of having a quantum critical point for which the tuning parameter is the magnetic field. The relationship between the resultant critical fluctuations and novel behavior very near the critical field is discussed.

Journal Article↗
PubMed2001

Spin-orbit coupling in the Mott insulator Ca(2)RuO(4).

O 1s x-ray absorption study of the Mott insulator Ca(2)RuO(4) shows that the orbital population of the 4d t(2g) band dramatically changes with temperature. In addition, spin-resolved circularly polarized photoemission study of Ca(2)RuO(4) shows that a substantial orbital angular momentum is induced in the Ru 4d t(2g) band. Based on the experimental results and model Hartree-Fock calculations, we argue that the cooperation between the strong spin-orbit coupling in the Ru 4d t(2g) band and the small distortion of the RuO(6) octahedra causes the interesting changeover of the spin and orbital anisotropy as a function of temperature.

Journal Article↗
PubMed2001

Observation of Andreev surface bound states in the 3-K phase region of Sr2RuO4.

The tunneling spectrum of the superconducting phase with Tc approximately 3.0 K has been measured in the Ru-embedded region of Sr2RuO4 using cleaved junctions. A sharp zero-bias conductance peak (ZBCP) has been observed below 3 K. All characteristics of this ZBCP suggest that it originates from Andreev surface bound states, indicating that the pairing in the 3-K phase is also non- s-wave. Below the bulk Tc of Sr2RuO4 (approximately 1.5 K), a crossover from sharp to bell-shaped ZBCP was found. This supports the theory that there is a phase transition in the 3-K phase region near the bulk Tc.

Journal Article↗
PubMed2001

Ultrasound attenuation in Sr(2)RuO(4): an angle-resolved study of the superconducting gap function.

We present a study of the electronic ultrasound attenuation alpha in the unconventional superconductor Sr(2)RuO(4). The power law behavior of alpha at temperatures down to T(c)/30 clearly indicates the presence of nodes in the gap. In the normal state, we find an enormous anisotropy of alpha in the basal plane of the tetragonal structure. In the superconducting state, the temperature dependence of alpha also exhibits significant anisotropy. We discuss these results in relation to possible gap functions.

Journal Article↗
PubMed2001

Anisotropy of magnetothermal conductivity in Sr2RuO4.

The dependence of in-plane and interplane thermal conductivities of Sr2RuO4 on temperature, as well as magnetic field strength and orientation, is reported. We found no notable anisotropy in the thermal conductivity for the magnetic field rotation parallel to the conducting plane in the whole range of experimental temperatures and fields, except in the vicinity of the upper critical field H(c2), where the anisotropy of the H(c2) itself plays a dominant role. This finding imposes strong constraints on the possible models of superconductivity in Sr2RuO4 and supports the existence of a superconducting gap with a line of nodes running orthogonal to the Fermi surface cylinder.

Journal Article↗
PubMed2001

Metamagnetism and critical fluctuations in high quality single crystals of the bilayer ruthenate Sr3Ru2O7.

We report the results of low temperature transport, specific heat, and magnetization measurements on high quality single crystals of the bilayer perovskite Sr3Ru2O7, which is a close relative of the unconventional superconductor Sr2RuO4. Metamagnetism is observed, and transport and thermodynamic evidence for associated critical fluctuations is presented. These relatively unusual fluctuations might be pictured as variations in the Fermi surface topography itself.

Journal Article↗
PubMed2001

Indomethacin induced bulky lymphadenopathy and eosinophilic pneumonia.

Indomethacin is one of the most popular non-steroidal anti-inflammatory drugs (NSAID). Although NSAID occasionally provoke bronchospasm and hypersensitivity pneumonia, they seldom cause lymphadenopathy. This is the first report in which NSAID induced both eosinophilic pneumonia and bulky intrathoracic lymphadenopathy simultaneously. A 76-year-old Japanese man experienced high fever and dyspnoea after using an indomethacin suppository. Computed tomography scan of his chest revealed massive mediastinal and hilar lymphadenopathy along with diffuse infiltration in both lungs. He was diagnosed to have eosinophilic pneumonia because of eosinophilia in his peripheral blood and bronchoalveolar lavage fluid (BALF). Without using glucocorticoids, the pulmonary infiltration and lymphadenopathy subsided spontaneously. As the blastoid transformation test using the lymphocytes in his BALF was positive to indomethacin, we judged that both his eosinophilic pneumonia and mediastinal lymphadenopathy were due to a hypersensitivity reaction to indomethacin. An allergic reaction to NSAID should be considered as a rare cause of mediastinal lymphadenopathy.

Aged↗
PubMed2001

Catheter closure of moderate to large sized patent ductus arteriosus using the simultaneous double or triple coil technique.

BACKGROUND: Although the clinical experience with transcatheter closure of the patent ductus arteriosus using the coils has grown rapidly, one important complication of this procedure using the conventional Gianturco coil was the migration of coils into peripheral vessels. This is especially for patients with a relatively larger size ductus and the risk for such complications could be increased. In this situation, the detachable coil may have some technical benefits to perform coil occlusion and reduce the incidence of complications. METHODS: We describe the clinical efficacy of a simultaneous double or triple coil occlusion technique using the Cook detachable coil or bioptome delivered 0.052 inch Gianturco coil to close the ductus arteriosus. This was performed in patients whose ductus diameter was greater than 3.0 mm. RESULTS: From February 1995 to December 2000, 118 patients with patent ductus arteriosus were treated by coil occlusion using Cook detachable coils, of whom 58 patients whose minimum diameter of ductus > or = 3.0 mm were reviewed. All patients had successful placement of coils. According to the evaluation by color flow mapping, a trivial shunt was observed in 17 patients (29%) within 24 h after the procedure. In 11 out of 17 patients, a residual shunt was not detected 1 month after the procedure. At 6 months after the procedure, the residual shunt was detected only in three patients. CONCLUSIONS: Although this study did not calculate the statistical significance between detachable and non-detachable coils in term of occlusion rate, our institutional experience suggests that the simultaneous double or triple coil technique using the detachable or 0.052 inch Gianturco coils can reduce the prevalence of coil migration or complications.

Adolescent↗
PubMed2001

Cardiovascular risk factors after Kawasaki disease: a case-control study.

OBJECTIVES: To determine cardiovascular risk profiles of patients with Kawasaki disease and to relate them to a noninvasive measure of endothelial function. STUDY DESIGN: Case-control study. Cardiovascular risk assessment including brachial artery reactivity was performed in 24 patients 11.3 +/- 1.8 (mean +/- SD) years after Kawasaki disease and in 11 subjects in a normal control group. RESULTS: The case versus control groups were similar regarding age, sex, race, body mass index, and percentage of ideal body weight, although cases had a higher mean z score of body mass index than normal (+1.00 +/- 1.18; P <.001). Cases had normal fasting total cholesterol levels but a higher mean z score of triglyceride levels (+1.35 +/- 2.04; P <.004). The case group had significantly higher mean systolic and diastolic resting blood pressure z scores (+0.76 +/- 1.06; P <.01 and +0.96 +/- 1.19; P <.01, respectively) than the control group and population norms. Endothelial function as indicated by brachial artery reactivity was not significantly different between the case versus control groups. In the case group higher blood pressure, increasing adiposity, and higher fasting triglyceride levels were significantly interrelated but did not relate to brachial artery reactivity or coronary artery abnormalities. CONCLUSIONS: Patients after Kawasaki disease tend to have a more adverse cardiovascular risk profile potentially indicative of an increased predisposition to premature atherosclerotic changes.

Adolescent↗
PubMed2001

Pulmonary intravascular lymphoma complicated with Pneumocystis carinii pneumonia: a case report.

We report a case of intravascular lymphoma (IVL) complicated with Pneumocystis carinii pneumonia (PCP). A 65-year-old male complaining of dyspnea and dementia was diagnosed to have pulmonary IVL by transbronchial lung biopsy. Concomitantly, deoxyribonucleic acid sequence specific to Pneumocystis carinii was detected in bronchoalveolar lavage fluid by polymerase chain reaction. Differential responses to the sequential treatments for PCP and IVL implied that increased serum lactate dehydrogenase (LDH) was due to PCP, whereas hypoxemia and dementia were due to IVL. Although pulmonary IVL and PCP share many clinical presentations, exact diagnosis is essential for their successful treatment.

Aged↗
PubMed2001

Construction of an infectious cDNA clone of Aichi virus (a new member of the family Picornaviridae) and mutational analysis of a stem-loop structure at the 5' end of the genome.

Aichi virus is the type species of a new genus, Kobuvirus, of the family Picornaviridae. In this study, we constructed a full-length cDNA clone of Aichi virus whose in vitro transcripts were infectious to Vero cells. During construction of the infectious cDNA clone, a novel sequence of 32 nucleotides was identified at the 5' end of the genome. Computer-assisted prediction of the secondary structure of the 5' end of the genome, including the novel sequence, suggested the formation of a stable stem-loop structure consisting of 42 nucleotides. The function of this stem-loop in virus replication was investigated using various site-directed mutants derived from the infectious cDNA clone. Our data indicated that correct folding of the stem-loop at the 5' end of the positive strand, but not at the 3' end of the negative strand, is critical for viral RNA replication. The primary sequence in the lower part of the stem was also suggested to be crucial for RNA replication. In contrast, nucleotide changes in the loop segment did not so severely reduce the efficiency of virus replication. A double mutant, in which both nucleotide stretches of the middle part of the stem were replaced by their complementary nucleotides, had efficient RNA replication and translation abilities but was unable to produce viruses. These results indicate that the stem-loop at the 5' end of the Aichi virus genome is an element involved in both viral RNA replication and production of infectious virus particles.

Amino Acid Sequence↗
PubMed2000

Polarized-neutron scattering study of the cooper-pair moment in Sr2RuO4.

We report a study of the magnetization density in the mixed state of the unconventional superconductor Sr2RuO4. On entering the superconducting state we find no change in the magnitude or distribution of the induced moment for a magnetic field of 1 T applied within the Ru O2 planes. Our results are consistent with a spin-triplet Cooper pairing with spins lying in the basal plane. This is in contrast with similar experiments performed on conventional and high- T(c) superconductors.

Journal Article↗
PubMed2000

Fermi surface, surface states, and surface reconstruction in Sr2RuO4

The electronic structure of Sr2RuO4 is investigated by high angular resolution ARPES at several incident photon energies. We address the controversial issues of the Fermi surface (FS) topology and the van Hove singularity at the M point, showing that a surface state and the replica of the primary FS due to sqrt[2]xsqrt[2] surface reconstruction are responsible for previous conflicting interpretations. The FS thus determined by ARPES is consistent with the de Haas-van Alphen results, and it provides additional information on the detailed shape of the alpha, beta, and gamma sheets.

Journal Article↗
PubMed2000

Temperature dependence of the penetration depth in Sr2RuO4: evidence for nodes in the gap function

We report measurements of the magnetic penetration depth in single crystals of Sr2RuO4 down to 0.04 K using a tunnel-diode based, self-inductive technique. We observe a power law temperature dependence below 0.8 K, with no sign of a second phase transition nor of a crossover predicted for a multiband superconductor. A power law dependence suggests that the gap function has nodes, inconsistent with candidate p-wave states. We argue that nonlocal effects, rather than impurity scattering, can explain the observed T2 dependence instead of the T-linear behavior expected for line nodes.

Journal Article↗
PubMed2000

Purification and characterization of diquat (1,1'-ethylene-2, 2'-dipyridylium)- metabolizing enzyme from paraquat-resistant rat liver cytosol.

To establish a paraquat-resistant Wistar rat strain, we carried out continuous sister-brother mating among rats that survived high-dose intraperitoneal administration of paraquat dichloride (360 mg/kg). The percentages of paraquat-resistant rats among wild rats and among the fifth-generations were 7.1% and 20.6%, respectively. After high-dose paraquat administration, the serum paraquat concentration in sensitive rats was much higher than that in paraquat-resistant rats. The cytosol fraction of liver from paraquat-resistant rats had higher paraquat- and diquat-metabolizing activities than that of liver from paraquat-sensitive rats. By contrast, microsomal fractions from livers of paraquat-resistant and paraquat-sensitive rats had no paraquat- or diquat-metabolizing activity. This paraquat/diquat-metabolizing enzyme was partially purified from paraquat-resistant rat liver cytosol using affinity chromatography for diquat. At the end of the purification procedure, rat liver diquat-metabolizing enzyme was purified 1154-fold to a final specific activity of 32.32 mol/h/mg protein, and an overall recovery of about 0.46% was obtained. This enzyme oxidized diquat to diquat-dipyridone during overnight incubation at 37 degrees C, but only metabolized traces of paraquat. The molecular mass of the enzyme was estimated as 190 kDa, and its isoelectric point of it was 4.6-4.7. Kinetic study revealed the values of K(m) and V(max) to be 35.0 micromol/l and 0.81 micromol/h/ml, respectively.

Animals↗