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S Maekawa

Publications and source records attributed to S Maekawa.

At least 19 recordsLinked to original sources
PubMed2006

Prognostic significance of subcarinal station in non-small cell lung cancer with T1-3 N2 disease.

BACKGROUND: Surgical resection may continue to offer the best chance of long-term survival for patients with non-small cell lung cancer (NSCLC). Generally, patients with N2 NSCLC have a poor prognosis. However, the surgical treatment of patients with N2 remains controversial as in these patients, some N2 subgroups have better prognoses than others. The objective of the current study was to evaluate the factors associated with N2, and to determine whether such factors are reliable predictors of survival. METHODS: We retrospectively reviewed 142 non-small cell lung cancer patients with T1-3 N2 in whom a curative approach had been attempted between January 1994 and December 2003. The patients were consequently divided into four groups (NS-1, no subcarinal involvement and without N1; NS-2, no subcarinal involvement and with N1; SI-1, subcarinal involvement and without upper mediastinal site; SI-2, subcarinal involvement and with upper mediastinal site). We also evaluated two groups for N2 stations (single-station N2 versus multiple-station N2). Multivariate analysis by Cox's proportional hazards regression model was performed to identify the prognosis. RESULTS: Lobectomy was carried out in 105 of the patients; bilobectomy in 10, and pneumonectomy in 27. The patients with T1-3 N2 disease showed survival rates of 34.1 % at 3 years and 24.1 % at 5 years. The overall survival rates at 3 years and 5 years were as follows: NS-1, 56.3 % and 43.2 %; NS-2, 35.4 % and 29.5 %; SI-1, 16.7 % and 0 %; SI-2, 15.4 % and 0 %, respectively. The NS-1 group had better prognoses than the other groups. There was a significant difference in survival rates within each group ( p = 0.0005). In univariate analysis, the type of surgery, type of subcarinal involvement, and multiple-station N2 were significantly associated with prognosis. Multivariate analysis showed that NS-1 was only found to be an independent prognostic factor in cases of T1-3 N2 disease ( p = 0.0018). NS-2 was not an independent factor but tended toward significance ( p = 0.0681). But multiple-station N2 was not an independent factor ( p = 0.1549). CONCLUSIONS: Surgery for patients with T1-3 N2 NSCLC might be acceptable if subcarinal lymph node metastasis is predicted to be absent.

Adenocarcinoma↗
PubMed2006

The value of tumor volume in surgically resected non-small cell lung cancer.

BACKGROUND: The aim of this study was to evaluate whether or not tumor volume (TV) has an impact on survival in non-small cell lung cancer. METHODS: In a retrospective analysis of 385 cases with NSCLC who underwent curative surgery between 1994 and 2003, we calculated the tumor volume by using an ellipsoidal formula. The patients were grouped according to TV as determined by histograms. Gender, age, histology, nodal involvement, size, and TV were analyzed. Multivariate analysis by Cox's proportional hazards regression model was performed to identify the prognosis. RESULTS: Cases of N0 showed a significantly lower TV than cases with other N statuses (p < 0.05). A significant difference was also observed between TV and histology or gender. The 189 patients belonging to the small volume group (SVG) (range, 0.105 to 9.265 cm3) had a significantly better overall survival rate than the other 196 patients in the large volume group (LVG) (9.266-366.522 cm3). With univariate analysis, gender, age, nodal involvement, size, and TV were significantly associated with prognosis. Multivariate analysis showed that only gender (p = 0.0184) and nodal involvement (p = 0.0001) were significantly independent prognostic factors. The size factor was not significant (p = 0.5285). However, TV was not an independent factor, but trending toward significance (p = 0.0801). CONCLUSIONS: Although TV provides no independent prognostic information with multivariate analysis, TV in NSCLC should be considered using volumetric measurement with a three-dimensional CT approach prior to surgery or treatment planning.

Aged↗
PubMed2006

Expressional screening of interferon-stimulated genes for antiviral activity against hepatitis C virus replication.

Type-I interferons (IFNs) and the interferon-stimulated genes (ISGs) play a major role in antivirus responses against hepatitis C virus (HCV) infection. In this study, we studied expression profiles of ISGs in cells supporting subgenomic HCV replication (Huh7/Rep), and screened their activities to suppress HCV replication. Real-time PCR analyses showed that the expression levels of 23 ISGs were significantly lower in Huh7/Rep than naive Huh7 cells due to transcriptional suppression of the interferon-stimulated response element (ISRE). Furthermore, the expression level of ISGs was also decreased in the cured Huh7 cells in which replicon had been eliminated (cHuh7), indicating adaptation of the cells to support HCV replication by downregulating ISGs. On the other hand, expression of HCV replicon was significantly suppressed by overexpression of several ISGs including PKR, MxA, IRF-9, GBP-1, IFI-6-16, IFI-27, 25OAS and IRF-1. Knock down of GBP-1, IFI-6-16 and IFI-27 by short hairpin RNA resulted in increase of HCV replication. Thus, we conclude that downregulation of ISG expression is required in the host cells supporting HCV replication and that several ISGs directly suppress HCV replication. The search for ISGs that regulate HCV replication may help to elucidate the cellular antiviral defence mechanisms against HCV infection.

Cell Line↗
PubMed2006

Site-specific mutation of the interferon sensitivity-determining region (ISDR) modulates hepatitis C virus replication.

The number of amino acid substitutions in the interferon sensitivity-determining region (ISDR) in the nonstructural 5A (NS5A) gene of hepatitis C virus (HCV) is closely associated with the interferon (IFN) response and viral load. Several HCV replicon-based studies have reported that ISDR sequences had an influence on viral replication in vitro. However, it is unclear as to how different ISDR sequences affect HCV replication. Various clinically observed ISDR sequences were introduced into HCV replicons and their contribution to viral replication was investigated using a colony formation assay and/or a transient replication assay. A mapping study of the ISDR was performed to identify the amino acid positions that critically affect replication. While no colonies were formed in the colony formation assay using HCV replicons with few mutations (0, 1 and 3) in the ISDR, numerous colonies (>200) appeared when using constructs with six mutations. Introduction of various distinct ISDR sequences with multiple mutations resulted in replication enhancement in transient assays. A mapping study identified several specific sites in the ISDR that critically affected replication, including codon 2209 which, in patients, was closely associated with a strong response to IFN. ISDR sequences associated with a clinical IFN response and viral load modulated the replication of HCV replicons, suggesting the importance of the ISDR sequence in HCV infection.

Amino Acid Sequence↗
PubMed2006

Prognosis of proximal femoral fracture in patients aged 90 years and older.

PURPOSE: To examine the walking ability and survival outcome of patients aged 90 years and older who sustained proximal femoral fractures, and to compare the findings with those of younger patients reported in previous studies. METHODS: Between January 1997 and June 2004 inclusive, 56 patients (11 men and 45 women) aged 90 years and older (range, 90-103 years; mean, 93 years) with hip fracture were reviewed. Their walking ability and survival outcome at discharge was investigated. Comparison was made between patients aged 60 to 89 years and those aged 90 years and older with respect to sex, fracture type, and other characteristics. RESULTS: Of 56 patients, 26 injured the right side and 30 the left side. Before injury, 33 (59%) were living at home and 23 (41%) were institutionalised in long-term care facilities or other hospitals. Fracture occurred at the femoral neck in 14 patients and at the trochanter in 42. Ten patients were treated conservatively because of severe dementia, co-morbidity, or refusal of surgery by the patients or their families, whereas 46 underwent surgery. Of the 45 who were previously ambulatory, 22 regained walking ability on discharge from hospital. None of the 10 patients treated conservatively were ambulatory on discharge. During hospitalisation, 4 became bedridden and 5 died (mainly due to pneumonia); among these 9 patients, 5 were deemed physically unfit for surgery. CONCLUSION: Surgery is the treatment of choice for patients aged 90 years and older with proximal femoral fracture. However, they have a lower rate of regaining pre-injury walking ability and a higher in-hospital death rate than younger patients.

Age Distribution↗
PubMed2005

Current-spin coupling for ferromagnetic domain walls in fine wires.

The coupling between a current and a domain wall is examined. In the presence of a finite current and in the absence of a potential which breaks the translational symmetry, there is a perfect transfer of angular momentum from the conduction electrons to the wall. As a result, the ground state is in uniform motion and this remains the case even when relaxation is included. This is described by, appropriately modified, Landau-Lifshitz-Gilbert equations. The results for a simple pinning model are compared with experiment.

Journal Article↗
PubMed2005

Superconducting pi qubit with a ferromagnetic Josephson junction.

Solid-state qubits have the potential for the large-scale integration and for the flexibility of layout for quantum computing. However, their short decoherence time due to the coupling to the environment remains an important problem to be overcome. We propose a new superconducting qubit which incorporates a spin-electronic device: the qubit consists of a superconducting ring with a ferromagnetic pi junction which has a metallic contact and a normal Josephson junction with an insulating barrier. Thus, a quantum coherent two-level state is formed without an external magnetic field. This feature and the simple structure of the qubit make it possible to reduce its size leading to a long decoherence time.

Journal Article↗
PubMed2005

Magnetic correlations in the Hubbard model on triangular and Kagomé lattices.

In order to study the magnetic properties of frustrated metallic systems, we present, for the first time, quantum Monte Carlo data on the magnetic susceptibility of the Hubbard model on triangular and kagomé lattices. We show that the underlying lattice structure determines the nature and the doping dependence of the magnetic fluctuations. In particular, in the doped kagomé case we find strong short-range magnetic correlations, which makes the metallic kagomé systems a promising field for studies of superconductivity.

Journal Article↗
PubMed2005

Momentum dependence of charge excitations in the electron-doped superconductor Nd1.85 Ce0.15 CuO4: a resonant inelastic x-ray scattering study.

We report a resonant inelastic x-ray scattering (RIXS) study of charge excitations in the electron-doped high-T(c) superconductor Nd1.85 Ce0.15 CuO4. The intraband and interband excitations across the Fermi energy are separated for the first time by tuning the experimental conditions properly to measure charge excitations at low energy. A dispersion relation with q-dependent width emerges clearly in the intraband excitation, while the intensity of the interband excitation is concentrated around 2 eV near the zone center. The experimental results are consistent with theoretical calculation of the RIXS spectra based on the Hubbard model.

Journal Article↗
PubMed2005

Mott gap excitations in twin-free YBa2Cu3O7-delta (Tc=93 K) studied by resonant inelastic x-ray scattering.

Mott gap excitations in the optimally doped high-T(c) superconductor YBa(2)Cu(3)O(7-delta) (T(c)=93 K) have been studied by the resonant inelastic x-ray scattering method. Anisotropic spectra in the ab plane are observed in a twin-free crystal. The excitation from the one-dimensional CuO chain is enhanced at 2 eV near the zone boundary of the b* direction, while the excitation from the CuO2 plane is broad at 1.5-4 eV and almost independent of the momentum transfer. Theoretical calculations based on the one-dimensional and two-dimensional Hubbard model reproduces the observed spectra when different values of the on-site Coulomb energy are assumed. The Mott gap of the CuO chain site is found to be much smaller than that of the CuO2 plane site.

Journal Article↗
PubMed2005

Effect of antiferromagnetic planes on the superconducting properties of multilayered high-Tc cuprates.

We propose a mechanism for high critical temperature (T(c)) in the coexistent phase of superconducting (SC) and antiferromagnetic (AFM) CuO2 planes in multilayered cuprates. The Josephson coupling between the SC planes separated by an AFM insulator (Mott insulator) is calculated perturbatively up to the fourth order in terms of the hopping integral between adjacent CuO2 planes. It is shown that the AFM exchange splitting in the AFM plane suppresses the so-called pi-Josephson coupling, and the long-ranged 0-Josephson coupling leads to coexistence with a rather high value of T(c).

Journal Article↗
PubMed2005

Surgical treatment for lung cancer with COPD based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD).

OBJECTIVE: The surgical indications for non-small cell carcinoma (NSCLC) with chronic obstructive pulmonary disease (COPD) are not well known. A classification of severity in COPD has been newly recommended by the US National Heart, Lung, and Blood Institute (NHLBI) and the World Health Organization (WHO). Therefore, based on this new system of classification, we review here a series of NSCLC patients with COPD who underwent lung resection at our hospital and attempt to identify the survival and morbidity of such patients. METHODS: We retrospectively reviewed the patients with NSCLC treated at our hospital between January 1994 and December 2002. Among these 640 patients, a curative approach was attempted in 50 with COPD (31 lobectomies, 11 segmentectomies, 8 bilobectomies). The patients were consequently divided into two groups (moderate group and severe group) according to the Global Iinitiative for Chronic Obstructive Lung disease (GOLD). Lung function was evaluated by FEV1 and FVC, and the survival rates were analyzed at 5 years. Postoperative morbidity was also compared between the two groups. RESULTS: FEV1 was 1.527 +/- 0.311 L in the moderate group compared with 1.025 +/- 0.224 L in the severe group ( p < 0.001). Postoperative decrease in FEV1 was lower compared to the predicted data of patients who underwent surgery for NSCLC with COPD. Postoperative pulmonary support such as mechanical ventilation or tracheotomy were necessary more frequently in the severe group. A significant difference was observed between the two groups in respiratory support ( p = 0.0102). Overall 5-year survival rate for NSCLC with COPD was 73.9 %, although there was no statistically significant difference between the moderate and severe groups in terms of survival. Lobectomy and segmentectomy show a remarkable advantage for the patients with bilobectomy, although this difference was not statistically significant. On the other hand, gender, degree of COPD, and histological type were shown to be not significant factors. Survival rate of these NSCLC patients with COPD were demonstrated to be comparable to those of the NSCLC patients without COPD in stages I and II. CONCLUSION: Stringent selection of candidates among NSCLC patients with a severe grade of COPD based on GOLD could be an acceptable and valuable approach compared to conventional patients without COPD, although NSCLC with severe COPD patients more frequently needed respiratory support.

Aged↗
PubMed2004

Low energy electronic states and triplet pairing in layered cobaltate.

The structure of the low-energy electronic states in layered cobaltates is considered starting from the Mott insulating limit. We argue that the coherent part of the wave functions and the Fermi-surface topology at low doping are strongly influenced by spin-orbit coupling of the correlated electrons on the t(2g) level. An effective t-J model based on mixed spin-orbital states is radically different from that for the cuprates, and supports unconventional, pseudospin-triplet pairing.

Journal Article↗
PubMed2004

Cortical selective vulnerability in motor neuron disease: a morphometric study.

Neuroimaging and neuropsychological studies have revealed that the primary motor cortex (PMC) and the extramotor cortical areas are functionally abnormal in motor neuron disease (MND, amyotrophic lateral sclerosis), but the nature of the cortical lesions that underlie these changes is poorly understood. In particular, there have been few attempts to quantify neuronal loss in the PMC and in other cortical areas in MND. We used SMI-32, an antibody against an epitope on non-phosphorylated neurofilament heavy chain, to analyse the size and density of SMI-32-positive cortical pyramidal neurons in layer V of the PMC, the dorsolateral prefrontal cortex (DLPFC) and the supragenual anterior cingulate cortex (ACC) in 13 MND and eight control subjects. There was a statistically significant reduction in the density of SMI-32-immunoreactive (IR) pyramidal neurons within cortical layer V in the PMC, the DLPFC and the ACC in MND subjects compared with controls [t (19) = 2.91, P = 0.009; estimated reduction 25%; 95% CI = 8%, 40%]. In addition, we studied the density and size of interneurons immunoreactive for the calcium-binding proteins calbindin-D(28K) (CB), parvalbumin (PV) and calretinin (CR) in the same areas (PMC, DLPFC and ACC). Statistically significant differences in the densities of CB-IR neurons were observed within cortical layers V (P = 0.003) and VI (P = 0.001) in MND cases compared with controls. The densities of CR- and PV-IR neurons were not significantly different between MND and control cases, although there were trends towards reductions of CR-IR neuronal density within the same layers and of PV-IR neuronal density within cortical layer VI. Loss of pyramidal neurons and of GABAergic interneurons is more widespread than has been appreciated and is present in areas associated with neuroimaging and cognitive abnormalities in MND. These findings support the notion that MND should be considered a multisystem disorder.

Aged↗
PubMed2004

Introduction of NS5A mutations enables subgenomic HCV replicon derived from chimpanzee-infectious HC-J4 isolate to replicate efficiently in Huh-7 cells.

Hepatitis C virus (HCV) subgenomic replicon has been reported to replicate efficiently and continuously in human hepatoma Huh-7 cells. To extend the previous results to other isolated HCV clones, we constructed another HCV replicon from HC-J4, one of chimpanzee-infectious HCV clones. An HCV replicon derived from HC-J4 (RpJ4) consists of HCV-5' untranslated region, neomycin phosphotransferase gene, the encephalomyocarditis virus internal ribosomal entry site, HCV nonstructural region, NS3 to NS5B, and HCV-3' untranslated region. The adaptive mutations known to be required for HCV-Con1 replicon were introduced in RpJ4 replicon, aa.(amino acids number according to HC-J4) 2197 serine to proline, deletion of serine at aa.2201, and aa.2204 serine to isoleucine (RpJ4-S2197P, RpJ4-S22001del, and RpJ4-S2204I). RpJ4/ISDR mutant and RpJ4-S2201del/ISDR mutant were also constructed by introducing six amino acid mutations into the interferon sensitivity determining region (ISDR). After transfection into Huh-7 cells and G418 selection, RpJ4 and RpJ4/ISDR mutants did not produce any colony. In contrast, G418-resistant cells were transduced efficiently by RpJ4-S2197P, RpJ4-S2204I, RpJ4-S2201del and RpJ4-S2201del/ISDR mutant, with the RpJ4-S2201del/ISDR mutant being most efficient. Hence the HCV replicon derived from HC-J4 can replicate efficiently following the introduction of adaptive mutations into the upstream region of ISDR. Moreover, additional introduction of mutations into ISDR further enhanced its replication. These findings demonstrate that the genetic structure of the NS5A domain is critical in HCV replications.

Amino Acid Sequence↗
PubMed2003

Electronic state of a CoO2 layer with hexagonal structure: a Kagomé lattice structure in a triangular lattice.

The electronic state in layered cobalt oxides with a hexagonal structure is examined. We find that the electronic structure reflects the nature of the Kagomé lattice hidden in the CoO2 layer which consists of stacked triangular lattices of oxygen ions and of cobalt ions. A fundamental model for the electron system is proposed, and the mechanism of the unique transport and magnetic properties of the cobalt oxides are discussed in light of the model.

Journal Article↗
PubMed2003

Kondo effect in quantum dots coupled to ferromagnetic leads.

We study the Kondo effect in a quantum dot coupled to ferromagnetic leads and analyze its properties as a function of the spin polarization of the leads. Based on a scaling approach, we predict that for parallel alignment of the magnetizations in the leads the strong-coupling limit of the Kondo effect is reached at a finite value of the magnetic field. Using an equation of motion technique, we study nonlinear transport through the dot. For parallel alignment, the zero-bias anomaly may be split even in the absence of an external magnetic field. For antiparallel spin alignment and symmetric coupling, the peak is split only in the presence of a magnetic field, but shows a characteristic asymmetry in amplitude and position.

Journal Article↗