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Tsuyoshi Kato

Publications and source records attributed to Tsuyoshi Kato.

At least 19 recordsLinked to original sources
PubMed2007

[Superficial small cell carcinoma of esophagus treated by endoscopic mucosal resection combined with chemoradiotherapy--a case report].

The patient was a 70-year-old woman who was admitted to our hospital for positive fecal occult blood. Upper gastrointestinal endoscopy revealed a superficial plateau-type (0- I sep) submucosal cancer on the right wall of the esophagus 28 cm from the incisor. Biopsy revealed small cell carcinoma. CT scan detected neither lymph node metastasis, nor distant organ metastasis. Endoscopic mucosal resection (EMR) was performed. Post-EMR chemoradiotherapies were conducted. The patient has lived with no evidence of cancer recurrence for 40 months. This was the first case of esophageal small cell carcinoma treated by EMR combined with chemoradiotherapy.

Aged↗
PubMed2006

Network-based de-noising improves prediction from microarray data.

BACKGROUND: Prediction of human cell response to anti-cancer drugs (compounds) from microarray data is a challenging problem, due to the noise properties of microarrays as well as the high variance of living cell responses to drugs. Hence there is a strong need for more practical and robust methods than standard methods for real-value prediction. RESULTS: We devised an extended version of the off-subspace noise-reduction (de-noising) method to incorporate heterogeneous network data such as sequence similarity or protein-protein interactions into a single framework. Using that method, we first de-noise the gene expression data for training and test data and also the drug-response data for training data. Then we predict the unknown responses of each drug from the de-noised input data. For ascertaining whether de-noising improves prediction or not, we carry out 12-fold cross-validation for assessment of the prediction performance. We use the Pearson's correlation coefficient between the true and predicted response values as the prediction performance. De-noising improves the prediction performance for 65% of drugs. Furthermore, we found that this noise reduction method is robust and effective even when a large amount of artificial noise is added to the input data. CONCLUSION: We found that our extended off-subspace noise-reduction method combining heterogeneous biological data is successful and quite useful to improve prediction of human cell cancer drug responses from microarray data.

Algorithms↗
PubMed2006

[A case of advanced gastric cancer with peritoneal metastasis that responded to paclitaxel plus 5-FU therapy].

We report a case in which paclitaxel (PTX) plus 5-FU therapy was remarkably effective for advanced gastric cancer with peritoneal metastasis. The patient was a 41-year-old woman who had type 4 gastric cancer with peritoneal metastasis. PTX plus 5-FU therapy was performed. The regimen included 600 mg/body/day of 5-FU by continuous iv administration from day 1 to 5 and consequent administration of PTX (90 mg/body) on days 8, 15 and 22 for 28 days repetitively. After 4 courses were completed, abdominal CT revealed that ascites had disappeared and the stomach wall had become thinner. Thus,we considered the patient had a partial response, and performed total gastrectomy. After the operation, PTX plus 5-FU therapy was used for 8 courses with the same regimen. No serious adverse event was observed,and the patient maintained good QOL throughout the treatment. No sign of progressive disease was seen for 12 months after the operation. However, 18 months after beginning the treatment, peritoneal metastasis became worse, and she died 19 months after treatment had begun. Considering the effectiveness and mild toxicity, PTX plus 5-FU therapy is thought to be useful for advanced gastric cancer.

Adenocarcinoma↗
PubMed2005

Time-dependent density functional theory investigation of electric field effects on absorption spectra of meso-meso-linked zinc porphyrin arrays: Role of charge-transfer States.

By using time-dependent density functional theory, we calculated the transition energies of a zinc porphyrin monomer and its meso-meso-linked arrays. In line with the prediction of the molecular exciton model, the calculated splitting energy of the Soret band increased as the number of linked porphyrins increased. We then examined how the transition energies of the dimer array were shifted by an applied electric field. For reproduction of an electroabsorption spectrum (EA), i.e., the field-induced change in absorption intensity, a model Hamiltonian constructed from five states is proposed. It is concluded for the dimer that the field-induced coupling between the lower-energy Soret band Se and the lower-lying ionic character (charge-transfer) states is responsible for the experimentally observed blue shift of Se as well as the second-derivative profile in the EA spectrum.

Journal Article↗
PubMed2005

Selective integration of multiple biological data for supervised network inference.

MOTIVATION: Inferring networks of proteins from biological data is a central issue of computational biology. Most network inference methods, including Bayesian networks, take unsupervised approaches in which the network is totally unknown in the beginning, and all the edges have to be predicted. A more realistic supervised framework, proposed recently, assumes that a substantial part of the network is known. We propose a new kernel-based method for supervised graph inference based on multiple types of biological datasets such as gene expression, phylogenetic profiles and amino acid sequences. Notably, our method assigns a weight to each type of dataset and thereby selects informative ones. Data selection is useful for reducing data collection costs. For example, when a similar network inference problem must be solved for other organisms, the dataset excluded by our algorithm need not be collected. RESULTS: First, we formulate supervised network inference as a kernel matrix completion problem, where the inference of edges boils down to estimation of missing entries of a kernel matrix. Then, an expectation-maximization algorithm is proposed to simultaneously infer the missing entries of the kernel matrix and the weights of multiple datasets. By introducing the weights, we can integrate multiple datasets selectively and thereby exclude irrelevant and noisy datasets. Our approach is favorably tested in two biological networks: a metabolic network and a protein interaction network. AVAILABILITY: Software is available on request.

Algorithms↗
PubMed2005

Experimental studies on the effects of recombinant human matrix metalloproteinases on herniated disc tissues--how to facilitate the natural resorption process of herniated discs.

PURPOSE: Recently, MMP-7 and MMP-3 have been found to play a crucial role in the natural resorption process of herniated discs. We therefore examined the role of these recombinant human matrix metalloproteinases (rh MMPs) in the treatment of herniated discs. METHODS: (a) Surgical samples of herniated disc were cultured in the presence or absence of rh MMPs, and wet weight was measured 24h later. (b) The rh MMPs were administered into normal rabbit intervertebral discs, and after 1 week spine samples were stained with Safranin O. (c) The rh MMPs were administered into canine herniated discs in vivo. Myelography and MRI were performed prior to and 1 week after administration. Spine samples were examined histologically. Whole disc tissue was collected, total protein was extracted, and Western blot analysis was performed. RESULTS: (a) Proteoglycan degradation was found in MMP-7, MMP-3, and chymopapain-treated samples. MMP-7 and chymopapain-treated samples displayed a significant loss in wet weight (p<0.01). (b) Normal disc tissues after administration of rh MMP-7, MMP-3, and chymopapain showed an extensive loss of Safranin O staining. (c) The rh MMP-7-treated discs had a marked decrease in protruded herniation by MRI. Herniated discs after administration of MMP-7 and chymopapain showed a significant decrease in protruded mass 7 days after administration compared with saline-treated discs when evaluated by myelography (p<0.01). The rh MMP-7-treated discs displayed a clear loss of Safranin O staining in the nucleus pulposus. Proteoglycan expression was barely detectable in disc tissues after MMP-7 administration, whereas obvious expression was obtained in saline-treated or untreated disc tissues. CONCLUSIONS: Exposure to rh MMP-7 resulted in promising proteoglycan loss in human surgical samples, normal rabbit intervertebral discs, and natural canine herniated discs. Administration of rh MMP-7 may facilitate the resorption process of herniated discs.

Adult↗
PubMed2004

Alkylating agents stronger than alkyl triflates.

A new class of potent electrophilic "R(+)" alkylating agents has been developed using weakly nucleophilic carborane anions as leaving groups. These reagents, R(CHB(11)Me(5)X(6)) (R = Me, Et, and i-Pr; X = Cl, Br), are prepared via metathesis reactions with conventional alkylating agents such as alkyl triflates, using the high oxophilicity of silylium ion-like species, Et(3)Si(carborane), as the driving force to obtain increased alkyl electrophilicity. The crystal structure of the isopropyl reagent, i-Pr(CHB(11)Me(5)Br(6)), has been determined, revealing covalence in the alkyl-carborane bonding. This contrasts with the free i-Pr(+) carbocation observed when the anion is less coordinating (e.g. Sb(2)F(11)(-)) or with tertiary alkyl centers, as in [tert-butyl][carborane] salts. In solution, the reagents exist as equilibrating isomers with the alkyl group at the 7-11 or 12 halide positions of the CB(11) icosahedral carborane anion. These alkylating agents are so electrophilic that they (a) react with alkanes at or below room temperature via hydride extraction to produce carbenium ions, (b) alkylate benzene without a Friedel-Crafts catalyst to give arenium ions, and (c) alkylate electron-deficient phosphorus compounds that are otherwise inert to conventional alkylating agents such as methyl triflate.

Alkylating Agents↗
PubMed2004

Optimal laser control of ultrafast photodissociation of I2- in water: mixed quantum/classical molecular dynamics simulation.

A linearized optimal control method in combination with mixed quantum/classical molecular dynamics simulation is used for numerically investigating the possibility of controlling photodissociation wave packets of I(2)(-) in water. Optimal pulses are designed using an ensemble of photodissociation samples, aiming at the creation of localized dissociation wave packets. Numerical results clearly show the effectiveness of the control although the control achievement is reduced with an increase in the internuclear distance associated with a target region. We introduce effective optimal pulses that are designed using a statistically averaged effective dissociation potential, and show that they semiquantitatively reproduce the control achievements calculated by using optimal pulses. The control mechanisms are interpreted from the time- and frequency-resolved spectra of the effective optimal pulses.

Journal Article↗
PubMed2004

Molecular alignment in a liquid induced by a nonresonant laser field: Molecular dynamics simulation.

We carried out molecular dynamics (MD) simulations for a dilute aqueous solution of pyrimidine in order to investigate the mechanisms of field-induced molecular alignment in a liquid phase. An anisotopically polarizable molecule can be aligned in a liquid phase by the interaction with a nonresonant intense laser field. We derived the effective forces induced by a nonresonant field on the basis of the concept of the average of the total potential over one optical cycle. The results of MD simulations show that a pyrimidine molecule is aligned in an aqueous solution by a linearly polarized field of light intensity I approximately 10(13) W/cm2 and wavelength lambda = 800 nm. The temporal behavior of field-induced alignment is adequately reproduced by the solution of the Fokker-Planck equation for a model system in which environmental fluctuations are represented by Gaussian white noise. From this analysis, we have revealed that the time required for alignment in a liquid phase is in the order of the reciprocals of rotational diffusion coefficients of a solute molecule. The degree of alignment is determined by the anisotropy of the polarizability of a molecule, light intensity, and temperature. We also discuss differences between the mechanisms of optical alignment in a gas phase and a liquid phase.

Journal Article↗
PubMed2004

Two-dimensional Raman and infrared vibrational spectroscopy for a harmonic oscillator system nonlinearly coupled with a colored noise bath.

Multidimensional vibrational response functions of a harmonic oscillator are reconsidered by assuming nonlinear system-bath couplings. In addition to a standard linear-linear (LL) system-bath interaction, we consider a square-linear (SL) interaction. The LL interaction causes the vibrational energy relaxation, while the SL interaction is mainly responsible for the vibrational phase relaxation. The dynamics of the relevant system are investigated by the numerical integration of the Gaussian-Markovian Fokker-Planck equation under the condition of strong couplings with a colored noise bath, where the conventional perturbative approach cannot be applied. The response functions for the fifth-order nonresonant Raman and the third-order infrared (or equivalently the second-order infrared and the seventh-order nonresonant Raman) spectra are calculated under the various combinations of the LL and the SL coupling strengths. Calculated two-dimensional response functions demonstrate that those spectroscopic techniques are very sensitive to the mechanism of the system-bath couplings and the correlation time of the bath fluctuation. We discuss the primary optical transition pathways involved to elucidate the corresponding spectroscopic features and to relate them to the microscopic sources of the vibrational nonlinearity induced by the system-bath interactions. Optical pathways for the fifth-order Raman spectroscopies from an "anisotropic" medium were newly found in this study, which were not predicted by the weak system-bath coupling theory or the standard Brownian harmonic oscillator model.

Journal Article↗
PubMed2004

Sequential dynamics of inflammatory cytokine, angiogenesis inducing factor and matrix degrading enzymes during spontaneous resorption of the herniated disc.

Intervertebral disc herniation (HD) is one of the most common orthopaedic conditions. MRI analysis of HD has revealed a spontaneous resorption mechanism related with neo-vascularization. It appears that the interaction of activated macrophages with disc tissues leads to the generation of inflammatory cytokines. Moreover, inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) is required for the induction of angiogenesis inducing factors such as vascular endothelial growth factor (VEGF) or matrix degrading enzymes such as MMP-3, MMP-7 and plasmin. We hypothesized that these molecules play a crucial role during spontaneous HD resorption. In this study, we have examined the sequential expression of these molecules using a co-culture system which is composed of the interaction of activated macrophages and disc tissues as a model of the acute response of inflammation occurred in HD. We have also considered the mechanism of activating latent MMPs during HD resorption process. Current our results indicate that upregulation of both TNF-alpha mRNA and protein expressions occur first in the inflammation induced by HD. VEGF upregulation follows the increased level of TNF-alpha expression. Both plasmin and MMP-3 are upregulated at later time points. We also demonstrate that both TNF-alpha and VEGF induce upregulated expression of urokinase-type plasminogen activator (u-PA). Our previous work has demonstrated that TNF-alpha could upregulate the expression of VEGF, MMP-3 and MMP-7 in the co-culture system. It has been reported that plasmin could affect to activate latent MMPs. Based on these findings, we suggest that TNF-alpha acts as the initiator of inflammation following contact between macrophages and disc chondrocytes and that plasmin and u-PA play a crucial role in activation of MMPs. We propose a spontaneous HD resorption cascade. Further understanding of the resorption process may provide future novel therapies for HD.

Animals↗
PubMed2003

Magnetically suspended centrifugal blood pump with an axially levitated motor.

The longevity of a rotary blood pump is mainly determined by the durability of its wearing mechanical parts such as bearings and seals. Magnetic suspension techniques can be used to eliminate these mechanical parts altogether. This article describes a magnetically suspended centrifugal blood pump using an axially levitated motor. The motor comprises an upper stator, a bottom stator, and a levitated rotor-impeller between the stators. The upper stator has permanent magnets to generate an attractive axial bias force on the rotor and electric magnets to control the inclination of the rotor. The bottom stator has electric magnets to generate attractive forces and rotating torque to control the axial displacement and rotation of the rotor. The radial displacement of the rotor is restricted by passive stability. A shrouded impeller is integrated within the rotor. The performance of the magnetic suspension and pump were evaluated in a closed mock loop circuit filled with water. The maximum amplitude of the rotor displacement in the axial direction was only 0.06 mm. The maximum possible rotational speed during levitation was 1,600 rpm. The maximum pressure head and flow rate were 120 mm Hg and 7 L/min, respectively. The pump shows promise as a ventricular assist device.

Biomedical Engineering↗