Biomedical subjects
Publications and source records attributed to K Yamada.
An 8-year-old intact male Shih Tzu dog was admitted with acute-onset tetraplegia. Magnetic resonance imaging showed an abnormality of the cervical intramedullary spinal cord. Histopathological examination of a spinal biopsy confirmed the presence of intravascular cartilaginous emboli. This is the first report of an antemortem diagnosis of fibrocartilaginous embolism in a chondrodystrophoid breed dog.
We investigated the relationship between the common cold and restenosis after percutaneous coronary intervention (PCI) in Japanese patients with angina pectoris, because suffering from a common cold during the follow-up period after PCI may be involved in the development of restenosis. In addition, we measured the soluble (s) L-selectin level early after PCI in patients with and without restenosis. The study group included 104 effort angina pectoris patients. We examined whether or not they had had a common cold in the 6 months following angioplasty. Finally, 88 patients, whose common cold status was known, were selected as the study subjects. Twelve patients caught a common cold after PCI. All of these patients were given antibiotics and/or anti-inflammatory agents and recovered within 2 weeks. None had clinically detectable influenza infection. Thirty-three patients suffered from restenosis and 55 did not. There was no significant difference in the restenosis frequency between effort angina pectoris patients with and without a common cold. The sL-selectin level was significantly increased in patients with restenosis early after PCI, whereas in patients without restenosis, sL-selectin remained unchanged. These findings suggest that restenosis development after PCI in patients with effort angina pectoris may involve leukocyte activation early after PCI, while suffering from a common cold during the follow-up period after PCI has no effect.
Surgical strategy for patients for lung cancer with coronary disease remains controversial. We performed concomitant off-pump coronary artery bypass grafting (off-pump CABG: OPCAB) and left lower lobectomy with ND 2a lymph nodes dissection for lung cancer with pneumoconiosis. After CABG, due to fixed adhesion of peribronchial lymph node, left lower lobectomy was hard to carry out. Postoperative management was done with much difficulty for massive sputum and pneumonia caused by chronic inflammatory lung disease. As a result, postoperative course has been uneventful for 2 years after operation. In the concomitant OPCAB and lung resection with chronic inflammatory lung disease, whether the synchronous or 2 periods operation was appropriate was still unknown. We think that careful pre- and intraoperative assessment for this disease is important.
We report here on the first direct observations of the vortex lattice in the bulk of electron-doped Nd1.85Ce0.15CuO4 single crystals. Using small-angle neutron scattering, we have observed a square vortex lattice with the nearest neighbors oriented at 45 degrees from the Cu-O bond direction, which is consistent with theories based on the d-wave superconducting gap. However, the square symmetry persists down to unusually low magnetic fields. Moreover, the diffracted intensity from the vortex lattice is found to decrease rapidly with increasing magnetic field.
Effects of magnetic fields (applied along the c axis) on static spin correlation were studied for the electron-doped superconductors Pr1-xLaCexCuO4 with x=0.11 (T(c)=25 K) and x=0.15 (T(c)=16 K) by neutron-scattering measurements. In the x=0.11 sample, which is located near the antiferromagnetic (AF) and superconducting phase boundary, a commensurate magnetic order develops below around T(c) at zero field. Upon applying a magnetic field up to 9 T both the magnetic intensity and the onset temperature of the order increase with the maximum field effect at approximately 5 T. In contrast, in the overdoped x=0.15 sample any static AF order is neither observed at zero field nor induced by the field up to 8.5 T. Difference and similarity of the field effect between the hole- and electron-doped high-T(c) cuprates are discussed.
We employ a new laterally coupled, vertical double dot with a tunable tunnel-coupling gate in a parallel configuration to study the electron spin and orbital dependence of quantum mechanical tunnel coupling on the size of the honeycomb vertices in the small electron numbers regime. We find a transition from the weak coupling regime, where fluctuations in tunnel coupling due to varying electron configuration dominate the anticrossings, to a regime where the two dots coalesce. We apply a magnetic field to ascertain the orbital angular momenta of the Fermi surface eigenstates, which correlate with anticrossing size, and we identify spin pairs with congruent behavior.
The clinical and radiological characteristics of swelling in the region of the medial clavicle may suggest the presence of a neoplastic or inflammatory lesion. This report describes a 27-year-old man with a painful tumor-like lesion over the medial clavicle, which was found to be a stress fracture caused by a nervous tic resulting from mental stress.
We report novel magnetic properties in the slightly hole-doped Mott-insulator La(2-x)SrxCuO4 via the La-nuclear quadrupole resonance (NQR) measurements. At x=0.018, the antiferromagnetic (AFM) La-NQR spectrum affected by internal fields comes out as the temperature decreases below T(N) approximately 150 K, whereas the nonmagnetic one persists to be observed down to a temperature T(f) approximately 20 K at which the nuclear-relaxation rate has a pronounced peak. This demonstrates that the phase separation of nonmagnetic and AFM phases occurs between T(f) and T(N). The novel phase separation is suggested as due to the partial destruction of the AFM phase caused by mobile holes via the formation of an extended spin-singlet state between Cu-derived spins and hole spins.
In the copper oxide parent compounds of the high-transition-temperature superconductors the valence electrons are localized--one per copper site--by strong intra-atomic Coulomb repulsion. A symptom of this localization is antiferromagnetism, where the spins of localized electrons alternate between up and down. Superconductivity appears when mobile 'holes' are doped into this insulating state, and it coexists with antiferromagnetic fluctuations. In one approach to describing the coexistence, the holes are believed to self-organize into 'stripes' that alternate with antiferromagnetic (insulating) regions within copper oxide planes, which would necessitate an unconventional mechanism of superconductivity. There is an apparent problem with this picture, however: measurements of magnetic excitations in superconducting YBa2Cu3O6+x near optimum doping are incompatible with the naive expectations for a material with stripes. Here we report neutron scattering measurements on stripe-ordered La1.875Ba0.125CuO4. We show that the measured excitations are, surprisingly, quite similar to those in YBa2Cu3O6+x (refs 9, 10) (that is, the predicted spectrum of magnetic excitations is wrong). We find instead that the observed spectrum can be understood within a stripe model by taking account of quantum excitations. Our results support the concept that stripe correlations are essential to high-transition-temperature superconductivity.
The dynamic spin susceptibility, chi(")(omega), has been measured over the energy range of 2</=omega</=10 meV for overdoped La2-xSrxCuO4. Incommensurate (IC) spin excitations are observed at 8 K for all superconducting samples for 0.25</=x</=0.28 with chi(") peaking at approximately 6 meV. The IC peaks at 6 meV become smaller in intensity with increasing x and, finally, become unobservable for a sample with x=0.30 which has no bulk superconductivity. The maximum chi(") decreases linearly with T(c)(onset) in the overdoped region, implying a direct cooperative relation between the spin fluctuations and the superconductivity.
Family-based linkage disequilibrium (LD) mapping has been suggested as a powerful and practical alternative to linkage analysis. We have performed a genome-wide LD survey of susceptibility loci for schizophrenia in a Japanese population. We first typed 119 schizophrenic pedigrees (357 individuals) using 444 microsatellite markers, and analyzed the data using the pedigree disequilibrium test. This analysis revealed 14 markers demonstrating significant transmission distortion. To corroborate these findings, the statistical methods were changed to the extended transmission disequilibrium test (ETDT), using 80 independent complete trios (schizophrenic proband and both parents), with 68 derived from initial pedigrees and 12 newly recruited trios. ETDT supported two markers for continued association, D11S987 on 11q13.3 (P = 0.00009) and D16S423 on 16p13.3 (P = 0.002). We scrutinized the most significant genomic locus on 11q11-13 by adding 26 new markers for analysis. Results of three-marker haplotype analysis in the region showed evidence of association with schizophrenia (most significant haplotype P = 0.0005, global P = 0.022). Although the present study may have missed other potential genomic intervals because of the sparse mapping density, we hope that it has identified promising anchor points for further studies to identify risk-conferring genes for schizophrenia in the Japanese population. In addition, we provide useful information on genomic LD structures in Japanese populations, which can be used for LD mapping of complex diseases.
Differences in prognosis and symptomatic treatment have highlighted the importance of the differential diagnosis of frontotemporal lobar degeneration (FTLD) and other dementias, but the variable clinical features make diagnosis difficult. We studied metabolic changes using multivoxel proton magnetic resonance spectroscopy (MRS) in regions of FTLD, including the posterior cingulate gyrus, which is also the area most affected by Alzheimer's disease (AD) in the early stages. We examined six patients with FTLD, six with presumed AD, and five healthy volunteers using repetition and echo times of 2000 and 135 ms. We analysed peak ratios of choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) from frontal and temporoparietal regions, basal ganglia, and posterior cingulate gyrus in both hemispheres. A decreased NAA/Cr ratio was observed in the posterior cingulate gyri in presumed AD (right: 1.56+/-0.44, P =0.011; left: 1.46+/-0.25, P =0.008) and FTD (right: 1.47+/-0.40, P =0.005; left: 1.36+/-0.32, P =0.002). No statistically significant changes in Cho/Cr were identified in the posterior cingulate gyri in presumed AD or FTLD, and no differences were observed in peak ratios in other regions. Decreased NAA may reflect neuronal activity in the posterior cingulate gyrus, and this study may contribute to insights into the pathophysiology of FTLD.
The electric quadrupole transition from the first 2(+) state to the ground 0(+) state in 16C is studied through measurement of the lifetime by a recoil shadow method applied to inelastically scattered radioactive 16C nuclei. The measured mean lifetime is 77+/-14(stat)+/-19(syst) ps. The central value of mean lifetime corresponds to a B(E2;2+(1)-->0(+)) value of 0.63e(2) fm(4), or 0.26 Weisskopf units. The transition strength is found to be anomalously small compared to the empirically predicted value.
BACKGROUND: The lateral suboccipital approach has been conventionally performed with the lateral, park-bench, or sitting position and the midline suboccipital approach has been performed in the prone position. We attempt to show the advantages of the prone oblique position in the surgery for posterior fossa lesions. METHODS: Twenty-two patients with posterior fossa lesions underwent surgery in the prone oblique position. The patients were fixed in the prone position while the operating table was rotated to raise the patient's shoulder. The surgeon sat beside the downward-shifted contralateral shoulder of the patient. With the lateral suboccipital approach, the neck of the patient was rotated to the side of the lesion. With the midline suboccipital approach, the neck was not rotated. FINDINGS: With the lateral suboccipital approach, this position spread the transverse axis of the suboccipital triangle and eliminated the interference of the patient's shoulder, providing an operative field that is wider than the lateral position or park bench position in all cases. With the midline suboccipital approach, this position enabled the surgeon to operate on lesions located in the upper half of the posterior fossa, such as fourth ventricular lesions or infratentorial lesions, without the need for a looking up posture with overhanging of the operative microscope. CONCLUSION: The prone oblique position offers the operator a panoramic view of the posterior fossa.
Neuropathy is one of the typical features of chronic complications of diabetes mellitus. Recent analyses indicate that subjects with impaired glucose tolerance (IGT) already have disturbance of peripheral nerve function. To test the role of adipocytokines, that tend to be abnormal in IGT subjects, on diabetic neuropathy, we analyzed the relationship between plasma adipocytokine levels (TNFalpha, adiponectin, and leptin) and nerve conduction velocity in 105 type 2 diabetic subjects (M/F = 66/39, age = 60.8 +/- 11.8 years, BMI = 24.7 +/- 5.0kg/m2). Adipocytokines were measured by ELISA, and motor conduction velocity (MCV) and sensory conduction velocity (SCV) in median, ulnar, and tibial nerve were measured by electrical stimulation. Motor conduction velocity and SCV were corrected by age to be 1.0 as the normal value, and the average of three nerves were used to be the representative value. Relationship between corrected MCV or corrected SCV as a dependent variable and the duration of diabetes, HbA1C, BMI, TNFalpha, adiponectin, and leptin concentrations as independent variables were analyzed by multiple regression. Duration of diabetes and HbA1C were highly related with both corrected MCV (P < 0.02 and P < 0.001) and SCV (P < 0.02 and P < 0.05) by this analysis. Only corrected SCV was related significantly with TNFalpha (P < 0.05), and close to significantly with leptin (P = 0.059) concentrations. These results indicate that increased plasma glucose levels and duration of diabetes are the major factors that modulate diabetic neuropathy. However, nerve function may be affected by plasma cytokine levels like TNFalpha, and this effect was more significant on sensory nerves than motor nerves. The present results suggest that adipocytokines may play a role not only on angiopathy but also on neuropathy in diabetics.
St. John's Wort (Hypericum perforatum, SJW) has been used as a herbal medicine for the treatment of depression in oral doses of 900-1050 mg/day in humans. However, the ingestion of SJW was reported to cause interactions with drugs. In the present study, we examined the effects of SJW treatment on the induction of drug transporters and enzymes in rats. An immunoblot analysis was performed to quantify the expression of the transporters and enzymes. SJW was given at a dose of 400 mg/kg/day, since it was reported that 400 mg/kg/day is antidepressant effective dose in rats. When SJW was administered for 10 days, the amounts of multidrug resistance protein 2 (MRP2), glutathione S-transferase-P (GST-P) and cytochrome P450 1A2 (CYP1A2) in the liver were increased to 304%, 252% and 357% of controls, respectively, although the amounts of P-glycoprotein and multidrug resistance protein 1 were not changed. Under the same conditions, an increase of MRP2 in the kidney was not observed. The increase in the levels of each protein was maximal at 10 days after SJW treatment and lasted for at least 30 consecutive days. These results suggest that SJW induces hepatic MRP2, GST-P and CYP1A2 overexpressions, and thus, it could affect drug metabolism, conjugation and disposition.
Temporomandibular joint (TMJ) osteoarthritis (OA) is a potential cause of craniofacial deformity. If TMJ OA appears during orthodontic treatment, the mandible usually rotates posteriorly, resulting in an unsatisfactory profile, especially in patients with pre-treatment mandibular retrusion. Although it is important to confirm the kind of TMJ pathosis at the start of orthodontic treatment, the relationship between TMJ OA, condylar remodelling and changes in craniofacial morphology remains unclear because of a lack of longitudinal studies. Elucidating this relationship might allow better prediction of post-treatment craniofacial morphology. In the present case reports, helical computed tomography and cephalometry were used to analyse relationships between the pattern and location of condylar remodelling and the changes in craniofacial morphology in three patients with TMJ OA.
We investigated the effect of insulin on the expression of the enhancer of split- and hairy-related protein-2 gene in 3T3-L1 adipocytes and L6 myotubes. The level of enhancer of split- and hairy-related protein-2 mRNA was increased by insulin in both cells. While both wortmannin and LY294002 blocked the increase in 3T3-L1 adipocytes, and only PD98059 was effective in L6 myotubes. Although the increase by insulin in these cells was inhibited by treatment with actinomycin D, this was enhanced by treatment with cycloheximide. Furthermore, cyclic AMP increased the level of enhancer of split- and hairy-related protein-2 mRNA in both cells in an additive manner. Thus, we conclude that insulin and cyclic AMP induce the expression of the enhancer of split- and hairy-related protein-2 gene in both 3T3-L1 adipocytes and L6 myotubes, and that the gene expression enhanced by insulin is regulated by the cell type-specific pathway. The former requires a phosphoinositide 3-kinase pathway and the latter a mitogen-activated protein kinase pathway.