Biomedical subjects

Y Kato

Publications and source records attributed to Y Kato.

At least 343 records · Page 19Linked to original sources

PubMed2000

Neuroendoscopy in microvascular decompression for trigeminal neuralgia and hemifacial spasm: technical note.

Miocrovascular decompression is an effective treatment for trigeminal neuralgia (TN) and hemifacial spasm (HFS). A complete cure cannot be obtained, and additional adjuncts for extended use of endoscopy are needed. The use of an endoscope combined with the operating microscope can enhance the surgeon's ability to view deep structures during operation. We study the application of combined microsurgical and endoscopic techniques in 21 cases of HFS and 12 cases of TN. With these techniques the surgeon can explore the ventral aspect of the brainstem and cranial nerves without further retraction, can see the groove caused by compression of the offending artery, and can confirm the proper position of the prosthesis after attachment to the dura by fibrin glue. In HFS the most common offending vessels in 75% of cases were the posterior inferior cerebellar artery (PICA) and anterior inferior cerebellar artery (AICA) and in 25% of cases the vertebral artery (VA). In trigeminal neuralgia the offending vessel in 60% of cases was the superior cerebellar artery (SCA), and in 40% of cases the AICA. The overall success rate was 97% with minimal morbidity 3% (facial palsy) and no mortality. The aim of this work is to study advantages and disadvantages of using endoscopy during microvascular decompression for TN and HFS.

Brain Stem↗

PubMed2000

Mechanism and prevention of enlargement or new development of aneurysm following treatment by clipping or coiling.

The mechanisms of cerebral aneurysm recurrence and enlargement were investigated in 11 patients: two with dissecting aneurysms, six with fully grown aneurysms after neck clipping, one with enlarged aneurysm after dome clipping, and two with enlarged aneurysm due to recanalization after GDC coil embolization. We concluded that it is fundamentally important to ensure complete attachment of the internal elastic lamina around the aneurysm neck by precise neck clipping and effective embolization, with accurate positioning of remaining internal elastic lamina.

Endothelium, Vascular↗

PubMed2000

Sternal tuberculosis in a 9-month-old infant after BCG vaccination.

UNLABELLED: Tuberculosis osteitis is mainly observed as a late complication of the pulmonary infection. We describe a 9-mo-old Japanese infant who became infected with Mycobacterium tuberculosis even after receiving Bacillus Calmette-Guerin (BCG) vaccination at 3 mo of age. This is the first report that the sternum is the localization for tuberculous osteitis in infants. He developed a localized tumor in the sternum without any respiratory symptom. Mycobacterium tuberculosis complex was detected by means of nucleic acid amplification test. Gastric aspirates also yielded Mycobacterium tuberculosis. The source of the infection was unclear. CONCLUSION: Tuberculous osteitis should be excluded in infants with undiagnosed bone lesions, even if they have been vaccinated with BCG.

Antitubercular Agents↗

PubMed2000

Superoxide dismutase-1 mutation-related neurotoxicity in familial amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by motor neuron system involvement, and is epidemiologically subclassified into sporadic, familial and endemic forms. About 20% of ALS families are associated with mutations in the gene for superoxide dismutase-1 (SOD1) encoded on chromosome 21q22.1. Several studies have pointed to a variety of functions of mutant SOD1, which has enhanced catalytic activity of the peroxynitrite-mediated tyrosine nitration, readily releases the reactive Cu ions, induces apoptotic cell death, has enhanced peroxidase activity, damages the mitochondria to release Ca2+, and forms SOD1-containing aggregates in the cytoplasm. Many of these studies have obtained evidence for increased oxidative damage in ALS. On the other hand, some reports disagree with oxidative damage involvement in SOD1 mutant ALS. In considering the findings of increased oxidative damage in mutant SOD1-expressing transgenic mice, it should be remembered that overexpression of mutant SOD1 may enhance oxidative stress generation from this enzyme. In this review, we present the clinicopathological features of SOD1 mutant familial ALS and its transgenic mouse model, and also discuss SOD1 mutation-related neurotoxicity, including SOD1 protein aggregation and post-translational protein modification.

Amyotrophic Lateral Sclerosis↗

PubMed2000

Suppression of BCR-ABL mRNA by various ribozymes in HeLa cells.

Ribozymes are RNA molecules with enzymatic activity that can cleave target RNA molecules in a sequence specific manner. To date, various types of ribozyme have been constructed to cleave other RNAs and such trans-acting ribozymes include hammerhead, hairpin and HDV ribozymes. External guide sequence (EGS) can also induce the suppression of a gene-expression by taking advantage of cellular RNase P. Here we compared the activities of various functional RNA cleavers both in vitro and in vivo. The first purpose of this comparison was intended to determine the best ribozyme motif with the highest activity in cells. The second purpose is to know the correlation between the activities of ribozymes in vitro and in vivo. Our results indicated that the intrinsic cleavage activity of ribozymes is not the sole determinant that is responsible for the activity of a ribozyme in cultured cells.

Endoribonucleases↗

PubMed2000

Regulatory role of C-terminal residues of SulA in its degradation by Lon protease in Escherichia coli.

The SulA protein is a cell division inhibitor in Escherichia coli, and is specifically degraded by Lon protease. To study the recognition site of SulA for Lon, we prepared a mutant SulA protein lacking the C-terminal 8 amino acid residues (SA8). This deletion protein was accumulated and stabilized more than native SulA in lon(+) cells in vivo. Moreover, the deletion SulA fused to maltose binding protein was not degraded by Lon protease, and did not stimulate the ATPase or peptidase activity of Lon in vitro, probably due to the much reduced interaction with Lon. A BIAcore study showed that SA8 directly interacts with Lon. These results suggest that SA8 of SulA was recognized by Lon protease. The SA8 peptide, KIHSNLYH, specifically inhibited the degradation of native SulA by Lon protease in vitro, but not that of casein. A mutant SA8, KAHSNLYH, KIASNLYH, or KIHSNAYH, also inhibited the degradation of SulA, while such peptides as KIHSNLYA did not. These results show that SulA has the specified rows of C-terminal 8 residues recognized by Lon, leading to facilitated binding and subsequent cleavage by Lon protease both in vivo and in vitro.

ATP-Binding Cassette Transporters↗

PubMed2000

EmPLiCS: an empirical approach for structure-based design of natural peptide drugs.

The computer implementation of a peptide drug-design strategy has been developed. The system is named EmPLiCS (Empirical Peptide Ligand Construction System) according to the strategy of the system, which searches for peptide-ligand structures by referring to empirical rules that are derived from known protein 3D structures. The system was tested on several known peptide-protein complexes. The results demonstrated the ability of this system to detect key residues of peptides that are crucial for interaction with their specific proteins. The system also showed the ability to detect the main chain trace of these peptides. Some of the main chain atoms were detected even though the complete primary structures were not reproduced, suggesting that main chain structure is important in peptide-protein recognition. The results of the present study demonstrated that the empirical rules-based system can generate significant information for use in the design of natural peptide drugs.

Algorithms↗

PubMed2000

Highly substituted glucuronoarabinoxylans (hsGAXs) and low-branched xylans show a distinct localization pattern in the tissues of Zea mays L.

Polyclonal antibodies which recognized highly substituted glucuronoarabinoxylans (hsGAXs) and low-branched xylans and did not cross-react with each other, were raised in order to examine localization of these epitopes in internodes of maize. Immunofluorescent labeling revealed different pattern between two succeeding developmental stages. The hsGAX epitope was localized evenly in primary walls in all tissue types, and strongly in unlignified secondary walls in phloem. However, lignified secondary walls in protoxylem, parenchyma and a part of fibers were faintly labeled with this epitope. Moreover, the epitope showed limited binding in lignified parenchyma and fiber walls at ultrastructural level. Low-branched xylan epitope was localized evenly throughout lignified walls in all tissue types. This epitope was also localized only in lignified walls of other organs such as leaf, root apex and dark-grown mesocotyl. Low-branched xylans are significantly related to lignification. Localization of hsGAX epitope in their organs was similar to that in internodes. The hsGAX epitope was distributed both in unlignified walls of all tissues and in lignified walls of parenchyma and annular thickening of protoxylem. We propose that hsGAX has separate functions in lignified and unlignified tissues. In conclusion, at tissue level, hsGAX is localized mainly in unlignified walls, and low-branched xylans in lignified walls.

Antibody Specificity↗

PubMed2000

HMB-45/melan-A and smooth muscle actin-positive clear-cell epithelioid tumor arising in the ligamentum teres hepatis: additional example of clear cell 'sugar' tumors.

HMB-45-positive clear-cell epithelioid tumor arising in the ligamentum teres hepatis of a 13-year-old Japanese girl is described. The well-defined tumor was completely removed and measured 9 x 7 x 6 cm. Cut sections showed a tan-white, homogeneous appearances with no hemorrhage or necrosis. The tumor was composed of nests or sheets of polygonal or oval-shaped cells rich in clear or finely granular cytoplasm. Capillary network was well developed, and sinusoid vessels were often seen with occasional perivascular hyalinization. There was moderate nuclear atypia but mitotic figures were absent. Periodic acid-Schiff stain showed a large amount of glycogen digested by diastase. Immunohistochemical stains for smooth muscle actin, Melan-A, and HMB-45 were positive in most of the tumor cells. Stains for vimentin, muscle actin, and HAM56 were focally positive, whereas stains for desmin, cytokeratin, epithelial membrane antigen, S-100, CD34, CD68, CD99, neurofilament proteins, and estrogen/progesterone receptors were negative. Ultrastructurally, the cytoplasm contained a considerable number of mitochondria, monoparticipate or membrane-bound glycogen, and longitudinally oriented thin filaments with focal condensations and subplasmalemmal densities. The histopathology of the present case, originally interpreted as epithelioid leiomyoma, was consistent with clear cell "sugar" tumors. The present case may indicate ubiquitous distribution of clear cell "sugar tumors" of which histogenesis remains unknown but is presumed to be of perivascular epithelioid cell origin.

Actins↗

PubMed2000

Radiographic parameters for evaluating the neurological spaces in experimental thoracolumbar burst fractures.

It is important to know the condition of neural spaces during the nonoperative treatment of thoracolumbar burst fractures. The goals of the current study were to identify the correlation between the degree of deformity of a fractured vertebra and the encroachment of neural spaces, and to determine how the encroachment and the deformity can be improved by the extension posture simulating the postural reduction. Experimental burst fractures were produced in L1 vertebrae of nine human thoracolumbar spine segments (T11-L3) with neural spaces lined with tiny steel balls. Lateral radiographs were taken in neutral and extended posture before and after the trauma. Anterior vertebral height, posterior vertebral height, vertebral height ratio, vertebral kyphotic angle, posterior vertebral body angle, and the cross diagonal angle were the geometric parameters used to describe the vertebral deformity. The canal diameter and superior and inferior intervertebral foramen areas were defined as the neural spaces. All parameters were measured on the scanned images of radiographs, as seen on the computer screen. Among the vertebral body parameters, the posterior vertebral height, posterior vertebral body angle, and cross diagonal angle showed significantly higher correlations with the canal encroachment. The extended posture did not improve the canal and intervertebral foramen encroachments. The kyphotic deformity (vertebral kyphotic angle and anterior vertebral height) was improved but the deformity of the vertebral posterior wall (posterior vertebral height and posterior vertebral body angle) was not improved because of the extended posture.

Adult↗

PubMed2000

Deep venous thrombosis after total hip or total knee arthroplasty in patients in Japan.

A single center, prospective, epidemiologic study was conducted to estimate the incidence of deep venous thrombosis detected by venography in patients in Japan undergoing total hip arthroplasty or total knee arthroplasty without prophylactic anticoagulant therapy. Venograms of 164 patients who had total hip arthroplasty and 138 patients who had total knee arthroplasty were evaluated. The incidences of deep venous thrombosis were 22.6% in patients who had total hip arthroplasty and 48.6% in those who had total knee arthroplasty. The incidences of proximal deep venous thrombosis were 9.8% in patients who had total hip arthroplasty and 14.5% in those who had total knee arthroplasty. Statistical analysis revealed that the type of operation influenced the development of deep venous thrombosis. Patients who had total knee arthroplasty were 3.2 times more likely to have deep venous thrombosis develop than were patients who had total hip arthroplasty. Body mass index and age were identified as statistically significant risk factors.

Adult↗

PubMed2000

Lactobacillus algidus sp. nov., a psychrophilic lactic acid bacterium isolated from vacuum-packaged refrigerated beef.

Lactobacillus algidus sp. nov. is described on the basis of 40 strains isolated as one of the predominant bacteria from five specimens of vacuum-packaged beef collected from different meat shops and stored at 2 degrees C for 3 weeks. These strains were quite uniform in the overall characteristics examined. They are facultatively anaerobic, psychrophilic, Gram-positive, non-spore-forming, non-motile, lactic acid-homofermentative rods. The cells occurred singly and in pairs on agar media and in rather long chains in broth media. They differed in several cultural and biochemical characteristics from the authentic meso-diaminopimelic acid-positive or psychrophilic lactic acid bacteria in the genera Lactobacillus, Carnobacterium and Brochothrix. The SDS-PAGE whole-cell protein pattern was clearly distinctive. DNA-DNA hybridization and phylogenetic analysis of 16S rDNA also failed to associate these strains closely with any of the validly described organisms used. The phylogenetic analysis showed that these strains are rather remotely but most closely related to Lactobacillus mali (93% sequence similarity), which belongs to the Lactobacillus casei/Pediococcus group. Therefore, these strains should be included in the genus Lactobacillus and considered to represent a new species, Lactobacillus algidus sp. nov. The type strain is M6A9T (= JCM 10491T).

Animals↗

PubMed2000

Evidence of relativistic laser beam filamentation in back-reflected images

The back-reflected image of a 100 TW laser incident on a long scale length plasma is measured. The plasma is deliberately preformed on a solid planar target in a controlled way. Multiple highly intense spots are observed inside the original focal spot. These spots could be the experimental evidence for the laser beam relativistic filamentation in the plasma. Three-dimensional particle-in-cell (PIC) simulations for parameters close to the experimental values are performed. The experimental observations and the filamentation dynamics obtained in the PIC simulations are in a good agreement.

Journal Article↗

PubMed2000

Prediction of pattern selection due to an interaction between longitudinal rolls and transverse modes in a flow through a rectangular channel heated from below

Convection patterns in a flow through a horizontal channel that is heated from below are predicted on the basis of a weakly nonlinear theory. At a certain value of the Reynolds number and the Rayleigh number, the conduction state with steady shear flow becomes linearly unstable to both longitudinal rolls and transverse modes, simultaneously. The longitudinal rolls align along the streamwise direction whereas the transverse modes are periodic in the streamwise direction. Amplitude equations for the interaction between the longitudinal rolls and the transverse modes are derived in a consistent manner. Coefficients in the equations are determined numerically for a wide range of parameters. The longitudinal rolls are found to bifurcate supercritically. On the other hand, the transverse modes bifurcate subcritically or supercritically, depending on the Prandtl number, the aspect ratio of the channel, and the boundary conditions on the sidewalls. Stable convection patterns are classified in a parameter space. A mixed mode pattern, which is a mixture of the components of the longitudinal rolls and the transverse modes, is found to be stable for some sets of parameters.

Journal Article↗

PubMed2000

High density collimated beams of relativistic ions produced by petawatt laser pulses in plasmas

Under optimal interaction conditions ions can be accelerated up to relativistic energies by a petawatt laser pulse in both underdense and overdense plasmas. Two-dimensional particle in cell simulations show that the laser pulse drills a channel through an underdense plasma slab due to relativistic self-focusing. Both ions and electrons are accelerated in the head region of the channel. However, ion acceleration is more effective at the end of the slab. Here electrons from the channel expand in vacuum and are followed by the ions dragged by the Coulomb force arising from charge separation. A similar mechanism of ion acceleration occurs when a superintense laser pulse interacts with a thin slab of overdense plasma and the pulse ponderomotive pressure moves all the electrons away from a finite-diameter spot.

Journal Article↗

PubMed2000

Exacerbation of vascular endothelial injury in the generalized Shwartzman reaction by the administration of anti-E-selectin antibody.

Previously, we reported that the consecutive administration of lipopolysaccharide (LPS) into LPS-sensitized mice for the generalized Shwartzman reaction (GSR) induced systemic injury of vascular endothelial cells. The aim of this study was to investigate the participation of vascular adhesion molecules in the vascular endothelial injury of GSR. The administration of anti-E-selectin antibody in GSR-induced mice resulted in massive apoptosis of vascular endothelial cells and congestion in blood vessels. Further, marked hemorrhage was found in the pulmonary alveoli of those mice. GSR, especially lung injury, was definitely exacerbated by the administration of anti-E-selectin antibody. On the other hand, the administration of anti-VCAM-1 antibody did not induce such injury of vascular endothelial cells. The possible role of E-selectin in the exacerbation of vascular endothelial injury in GSR is discussed.

Animals↗

PubMed2000

Morphological change in Pseudomonas aeruginosa following antibiotic treatment of experimental infection in mice and its relation to susceptibility to phagocytosis and to release of endotoxin.

The relationship between morphological changes in Pseudomonas aeruginosa following antibiotic treatment of experimental infection in mice, susceptibility to phagocytosis, and release of endotoxin was studied. The intraperitoneal administration of P. aeruginosa with imipenem or ceftazidime into mice induced morphological changes in the cells 2 h after injection. Round P. aeruginosa cells with imipenem treatment became susceptible to phagocytosis by peritoneal cells, whereas long filamentous cells with ceftazidime treatment were hardly phagocytized by peritoneal cells. The morphological changes also affected the plasma endotoxin level in the circulation.

Animals↗

PubMed2000

In vitro antimicrobial properties of recombinant ASABF, an antimicrobial peptide isolated from the nematode Ascaris suum.

ASABF is a CSalphabeta-type antimicrobial peptide that contains four intramolecular disulfide bridges (Y. Kato and S. Komatsu, J. Biol. Chem. 271:30493-30498, 1996). In the present study, a recombinant ASABF was produced by using a yeast expression system, and its antimicrobial activity was characterized in detail. The recombinant ASABF was active against all gram-positive bacteria tested (7 of 7; minimum bactericidal concentration [MBC], 0.03 to 1 microg/ml) except Leuconostoc mesenteroides, some gram-negative bacteria (8 of 14; MBC, >0.5 microg/ml), and some yeasts (3 of 9; MBC >3 microg/ml). Slight hemolytic activity (4.2% at 100 microg/ml) against human erythrocytes was observed only under low-ionic-strength conditions. Less than 1 min of contact was enough to kill Staphylococcus aureus ATCC 6538P. The bactericidal activity against S. aureus was inhibited by salts.

Amino Acid Sequence↗