Biomedical subjects

K Kimoto

Publications and source records attributed to K Kimoto.

At least 19 recordsLinked to original sources

PubMed2006

Relationship of bacterial strains to clinical syndromes of Campylobacter-associated neuropathies.

BACKGROUND: Clinical and serologic studies suggest that Guillain-Barré syndrome (GBS) and atypical GBS with preserved muscle stretch reflexes (MSRs) form a continuous spectrum as well as do Fisher syndrome (FS), FS/GBS overlap, Bickerstaff brainstem encephalitis (BBE), BBE/GBS overlap, acute ophthalmoparesis (AO), ataxic GBS, and acute oropharyngeal palsy. OBJECTIVE: To clarify the spectrum of neurologic disorders that occur subsequent to Campylobacter jejuni enteritis. METHODS: We recruited patients with various neurologic conditions and from whom C jejuni was isolated. Bacterial features were investigated. RESULTS: Diagnoses for the patients from whom C jejuni was isolated were GBS (n = 90), FS (n = 22), MSR-preserved GBS (n = 10), FS/GBS (n = 6), BBE (n = 1), BBE/GBS (n = 2), AO (n = 3), ataxic GBS (n = 1), and acute oropharyngeal palsy (n = 3). Isolates from MSR-preserved GBS were similar to those of GBS in serotype (HS:19), genotype (lipo-oligosaccharide [LOS] locus class A or B, cst-II genotype [Thr51]), and GM1 or GD1a epitope expression on LOS. FS/GBS overlap, BBE, BBE/GBS overlap, AO, ataxic GBS, and acute oropharyngeal palsy isolates were similar to those of FS in serotype (HS:2 or HS:4-complex), genotype (LOS locus class A or B, cst-II genotype [Asn51]), and GQ1b epitope expression on LOS. CONCLUSIONS: The bacterial findings support the proposal that Guillain-Barré syndrome (GBS) and muscle stretch reflex-preserved GBS comprise a continuous spectrum as well as do Fisher syndrome (FS), FS/GBS overlap, Bickerstaff brainstem encephalitis (BBE), BBE/GBS overlap, acute ophthalmoparesis, ataxic GBS, and acute oropharyngeal palsy.

Adolescent↗

PubMed2006

Image-based sizing of surface-breaking cracks by SH-wave array ultrasonic testing.

This paper presents calibration-free crack sizing techniques based on ultrasonic imaging. The techniques are intended for 2D (line) surface-breaking cracks with the size of the incident wavelength or greater. The probing wave mode is the anti-plane shear wave (SH-wave). Two methods are employed for the ultrasonic imaging. One is a synthetic aperture focusing technique (SAFT) and the other is a computed time-reversal focusing technique (TRFT). In this paper, those methods are modified so that crack tips are located directly from measured A-scope waveforms without any calibration experiments. The results are shown as a peak in the ultrasonic image created by the respective methods. Reasonable accuracies of the proposed techniques are demonstrated first for the sizing of slits with known depths. The techniques are applied thereafter to the sizing of fatigue cracks. Since fatigue cracks may not be open without an external load, ultrasonic measurements are taken with and without external loads. The results of the imaging show that the depths of open cracks can be estimated accurately. It is also shown that crack opening (closing) behavior can be deduced by observing appearance (disappearance) of the peak in the images indicating the crack tip.

Algorithms↗

PubMed2005

Observation of magnetic ripple and nanowidth domains in a layered ferromagnet.

We investigated ferromagnetic domain structures on nanometer to micrometer scale for single crystals of a layered ferromagnet, La(2-2x)Sr(1+2x)Mn2O7 (0.32 < or = x < or = 0.40), as functions of x and temperature by means of Lorentz electron microscopy. We have succeeded in observing the evolution of magnetic ripple structure, dynamically, related to a spin reorientation transition where the magnetization direction switches between parallel and perpendicular to the layers. Our high-resolution magnetic domain imaging revealed that the ripple state is characterized by the evolution of magnetic nanowidth domains.

Journal Article↗

PubMed2005

Suppression of stress-induced nNOS expression in the rat hypothalamus by biting.

Nitric oxide (.NO) modulates the activity of the endocrine system in the behavioral response to stress. The purpose of this study was to investigate the effect of restraining the body of an animal on expression of neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) of the hypothalamus, and the inhibitory effect of para-masticatory activity on restraint-induced nNOS expression. We observed an increase in nNOS mRNA expression and nNOS-positive neurons in the rat hypothalamus after 30 or 60 min of restraint. Biting on a wooden stick during bodily restraint decreased nNOS mRNA expression in the hypothalamus. In addition, the number of nNOS-positive neurons was significantly reduced in the PVN of the hypothalamus. These observations clearly suggest a possible anti-stress effect of the masticatory activity of biting, and this mechanism might be unconsciously in operation during exposure to psychological stressors.

Adaptation, Psychological↗

PubMed2003

Genetic variation in hypoxia-inducible factor 1alpha and its possible association with high altitude adaptation in Sherpas.

Hypoxic stress at high altitude requires adaptations in several physiological functions to ensure the optimal oxygenation of all cells. Several lines of evidence suggested that high-altitude native populations such as Sherpas have been genetically adapted to their stressful environment. We investigated the genetic variation in the hypoxia-inducible factor (HIF)-1alpha gene in Sherpas as compared with Japanese, native lowlanders, and found a novel dinucleotide repeat polymorphism in intron 13 of the HIF-1alpha gene. GT15 allele was more frequent in Japanese than in Sherpas with statistical significance, while GT14 allele was significantly more frequent in Sherpas as compared with Japanese. A possible genetic variation in the HIF-1alpha gene might function in adaptation to living at high altitude. Because the activity of HIF-1 is regulated by multiple steps including the transcriptional level, the effect of the polymorphism in intron 13 on the cellular hypoxic responses remains to be elucidated.

Adaptation, Physiological↗

PubMed2003

Effect of different proton pump inhibitors, differences in CYP2C19 genotype and antibiotic resistance on the eradication rate of Helicobacter pylori infection by a 1-week regimen of proton pump inhibitor, amoxicillin and clarithromycin.

AIM: To investigate the effect of different proton pump inhibitors, S-mephenytoin 4'-hydroxylase (CYP2C19) genotype and antibiotic susceptibility on the eradication rate of Helicobacter pylori. METHODS: One hundred and eighty-seven H. pylori-infected peptic ulcer patients were randomly treated with either rabeprazole (10 mg b.d.) or lansoprazole (30 mg b.d.) plus amoxicillin (750 mg b.d.) and clarithromycin (400 mg b.d.) for 1 week. The antibiotic susceptibility and CYP2C19 genotype (extensive or poor metabolizer) were investigated. RESULTS: The eradication rates in the rabeprazole-amoxicillin-clarithromycin (RAC) and lansoprazole-amoxicillin-clarithromycin (LAC) groups were 75% and 69%, respectively, on an intention-to-treat basis, and 80% and 75%, respectively, on a per protocol basis. The eradication rate for clarithromycin-resistant strains was significantly lower than that for clarithromycin-sensitive strains (24% vs. 86%, P < 0.05). For clarithromycin-sensitive strains in the LAC group, there was a tendency for a lower eradication rate in extensive than poor metabolizers. The eradication rate in extensive metabolizers in the RAC group tended to be higher than that in extensive metabolizers in the LAC group (89% vs. 78%, P = 0.079726). CONCLUSIONS: The success of the 1-week proton pump inhibitor-amoxicillin-clarithromycin regimen depends on the susceptibility of H. pylori to clarithromycin. Moreover, differences in CYP2C19 genotype influence the eradication rates of lansoprazole-based therapy, and the rabeprazole-based regimen has an advantage especially in extensive metabolizers.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2002

Ferromagnetic domain structures and nanoclusters in Nd(1/2)Sr(1/2)MnO3.

Magnetic domain structures of Nd(1/2)Sr(1/2)MnO3 were investigated by means of low-temperature Lorentz electron microscopy. On cooling, magnetic domain walls started to appear at 250 K, and they were oriented straight along the [100] and [110] directions. With a further decrease in temperature, the volume of each magnetic domain increased with discontinuous domain-wall jumps. A characteristic granular image was observed at around 140 K, near the charge-ordering transition temperature. We consider that this originated from ferromagnetic nanoclusters that appeared in the antiferromagnetic matrix.

Journal Article↗

PubMed2002

Charge/orbital ordering structure of Pr(1-x)Ca(x)MnO(3)(x = 3/8) examined by low-temperature transmission electron microscopy.

The structural phase transition of Pr(1-x)Ca(x)MnO(3)(x = 3/8) was investigated by means of low-temperature transmission electron microscopy. Superlattice reflection spots with a modulation wave vector q(1) = (0,1/2,0) appeared below 230 K, indicating formation of the d(3x(2-r(2))/d(3y(2)-r(2)) type of charge/orbital ordering. Below 150 K, a new series of superlattice reflection spots with a modulation wave vector q(2) = (1/4,1/4,1/2) appeared, suggesting an additional ordering of excess 1/8 Mn(3+), necessary due to the deviation of x from 1/2, with the occupation of the d(3z(2-r(2)) type of e(g) orbital.

Journal Article↗

PubMed2002

Software techniques for EELS to realize about 0.3 eV energy resolution using 300 kV FEG-TEM.

In this short communication we describe some software techniques for electron energy-loss spectrum measurement. We prepared DigitalMicrograph (Gatan) scripts for multiple spectrum acquisitions, quasi-simultaneous acquisition of low-loss and core-loss spectra, energy drift correction, and other operations. Narrow zero-loss spread of 0.27 eV is demonstrated using a 300 kV field-emission transmission electron microscope (TEM) (Hitachi, HF-3000) and a post-column energy filter (Gatan, GIF2002). The core-loss spectrum is acquired with an energy resolution of 0.36 eV with high reproducibility. The present software techniques effectively achieve the intrinsic energy resolution of electron sources. Sample scripts are provided in the Appendix.

Journal Article↗

PubMed2002

Correlation between elevator muscle activity and direction of sagittal closing pathway during unilateral chewing.

The closing pathway of masticatory movement in the vicinity of the intercuspal position (ICP) is considered as a functional movement in reconstructing the occlusal guidance. The purpose of this study was to examine a correlation between elevator muscle activity and direction of the closing pathway in the vicinity of the ICP during mastication. Fifty subjects (18 male and 32 female subjects aged from 21 to 34 years) were selected randomly from the students of the Kanagawa Dental College. The measurements of jaw movement during mastication were recorded using a Sirognathograph instrument and surface electromyography (EMG) of the anterior temporalis and masseter muscles simultaneously. The muscle activity and the direction of the closing pathway were calculated on the working and non-working sides during unilateral chewing and analysed at the sections of ICP-2 mm and 2-4 mm in sagittal view. The direction of the closing pathway was expressed by the angle to a vertical reference axis. The direction of the closing pathway correlated significantly with the activity of the anterior temporalis muscles on the non-working side and the masseter muscles on the working side at ICP-2 mm. From the results of this study, it was suggested that the elevator muscle activity may be associated with the direction of the closing pathway during mastication.

Adult↗

PubMed2001

Survival activity of troglitazone in rat motoneurones.

Troglitazone (TGZ), an antidiabetic drug that improves insulin-resistance in the peripheral tissues, was tested for neurotrophic activity in motoneurones and other neurones in culture. In rat motoneurones, TGZ had a remarkable effect on survival, which was comparable or superior to that of brain-derived neurotrophic factor, a known potent neurotrophic factor for rat motoneurones. However, TGZ did not promote the survival of sensory, sympathetic, septal or hippocampal neurones. The effect of TGZ on motoneurones was additive to that of insulin-like growth factor-I and both activities were inhibited by phosphatidylinositol 3-kinase (PI3-kinase) inhibitors, wortmannin and LY294002, suggesting the involvement of the activation of PI3-kinase in the activity of TGZ. Pioglitazone, another antidiabetic drug structurally similar to TGZ, did not show any activity, indicating that the agonistic activity of TGZ for peroxisome proliferator-activated receptor-gamma is not involved in the survival activity. Chromanol, an antioxidant moiety of TGZ, showed little or no survival activity. These results indicate specific neurotrophic activity of TGZ for motoneurones through the activation of PI3-kinase and support the applicability of TGZ for the treatment of motor neurone diseases such as amyotrophic lateral sclerosis.

Animals↗

PubMed2001

Light element analysis in oxycarbonate superconductors using EELS.

Elemental analysis in an oxycarbonate superconductor ((Cu,N,C)Sr2CaCu2Oy) is conducted using transmission electron microscope-electron energy-loss spectroscopy with detector-gain correction. The gain correction enables highly sensitive elemental analysis and precise measurement of energy-loss near edge structures (ELNESs). It is found that carbon is included as a CO3 group, because the carbon K-edge in the oxycarbonate shows the same ELNES observed from CaCO3. Nitrogen ELNES is similar to that of Sr(NO3)2, so nitrogen is contained as a NO3 group. Although both CO3(2-) and NO3- have similar planar atomic arrangements, the nitrogen ELNES observed is different from that of carbon. EEL spectrum simulation based on DV-Xalpha method is used to interpret the difference.

Journal Article↗

PubMed2001

Fourier images feature of lattice fringes formed by low-loss electrons as observed using spatially-resolved EELS technique.

The lattice fringes of inelastically scattered electrons were investigated using spatially-resolved electron energy-loss spectroscopy (EELS) technique. The intensity profiles of lattice fringes formed by low-loss electrons were observed, and their position and contrast were elucidated with high spatial resolution. It was found that the conventional transmission electron microscope image includes low-loss images, which are the integrated image of through-focus images weighted by the intensity of the EEL spectrum. The modulation feature in the lattice fringes of inelastically scattered electrons is similar to the Fourier images. It means that the exit wave field of elastically scattered electrons is almost preserved in that of low-loss electrons.

Journal Article↗

PubMed2001

HRTEM study of new series of oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6).

Arrangements of Cu and anion groups (CO3 and NO3) in the charge-reservoir (CR) blocks of a series of new oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6) were examined by means of electron diffraction and high-resolution transmission electron microscopy (HRTEM). The first three members with n = 1-3 [Tc = 33 K (n = 1), 91 K (n = 2), 90 K (n = 3)] show the 4a0-type superstructures with periodic arrangements, [-Cu-X-X-X-Cu-X-X-X-Cu-] (X = CO3, NO3), in the CR blocks. The third member (n = 3) partly contains the 2a0-type of superstructure with [-Cu-X-Cu-X-Cu] in the CR blocks. The fourth member with n = 4 (Tc = 113 K) contains only the 2a0-type of superstructure. The higher members, with n = 5 (Tc = 65 K) and n = 6 (Tc = 52 K), show no evidence of ordering in the CR blocks, suggesting random arrangements of Cu and anion groups.

Journal Article↗

PubMed2001

Spatially-resolved EELS analysis of multilayer using EFTEM and STEM.

Spatially-resolved electron energy-loss spectroscopy (EELS) is applied to the multilayer (SiO2/Si3N4/SiOxNy/Si), a common semiconductor device structure. To observe depth profile at sub-nanometre spatial resolution, scanning transmission electron microscopy (STEM) and energy-filtering transmission electron microscopy (EFTEM)-based techniques are compared in practical application. STEM-based EELS is useful in simultaneously analysing plural elements. EFTEM-based EELS is suitable for analysing the chemical shift and core loss intensity of single element. The practical spatial resolution is of the same order for each technique, both involving beam damage, which can be reduced by decreasing current density in EFTEM and avoiding beam overlapping in STEM.

Journal Article↗

PubMed2001

[Relations between taking contraceptive pills, condom use and sexually transmitted disease history among female sex workers].

PURPOSE: The aim of this study was to analyze how taking contraceptive pills and condom use are related to each other, and their links to sexually transmitted disease (STD) history among female sex workers. METHOD: A cross-sectional study was performed by means of a standardized questionnaire self-administered by sex workers who attended a STD Clinic in Osaka between 1st April, 1998 and 31st March, 1999. They came to the clinic for routine screening for STDs and HIV (Human Immunodeficiency Virus) infection, and for treatment. The responses of a total of 92 sex workers, who are basically expected to use condoms and identified themselves as "sex workers at bath houses", "sex workers in former red light districts", "sex massage providers on call" and "call girls" on the questionnaires, were analyzed. RESULT: The proportion of sex workers who were diagnosed with chlamydial infection either currently or over the previous year was higher among sex workers who answered they take contraceptive pills "regularly" (pill users) than in those who answered "irregularly" or "not" (non-pill users). This finding was statistically significant for those whose education was less than 12 years, whose professional career as a sex worker was 1 year or more, and whose average daily income was 50,000 yen (US$450) or more. Except for the group whose income was less than 50,000 yen, the proportion of sex workers in all groups who were diagnosed with chlamydial infection was greater, although the difference was not statistically significant, among pill users than among non-users. The proportion of sex workers who use condoms "regularly and correctly" was significantly higher for non-pill users than for those using the pills. Multiple logistic regression analysis showed that pill use was significantly related to condom "not or irregular or incorrect" use (Odds ratio: 4.43, CI 1.12-17.60). The proportion of sex workers with a chlamydial infection history was significantly lower with those using condoms "regularly and correctly" than in those who do not use condoms or employ them "irregularly or incorrectly" (Odds ratio: 0.08, CI 0.01-0.68). CONCLUSION: This study showed the proportion of sex workers diagnosed with chlamydial infection to be higher among pill users than among non-users and the proportion of sex workers who use condoms "regularly and correctly" was higher among non-pill users than among users. These findings suggest that irregular, incorrect or non use of condoms among pill users may cause chlamydial infection.

Adolescent↗

PubMed2001

Increased concentrations of protein gene product 9.5 in the synovial fluid from horses with osteoarthritis.

Our previous study established protein gene product 9.5 (PGP 9.5), a ubiquitin C-terminal hydrolase, as a specific cytochemical marker of synovial lining cells (type B synoviocytes) in the horse joint. The present study aimed to detect PGP 9.5 in the synovial fluid and shows that PGP 9.5 is a valuable marker of osteoarthritis in the horse. Immunohistochemical staining confirmed rich and consistent localization of PGP 9.5 immunoreactivity in the cytoplasm of synovial lining cells in the normal horse joint. Western blot analysis of synovial fluid from normal joints could detect a significant band corresponding to that contained in the brain and synovial membrane extracts. When 60 synovial fluid samples from normal and abnormal joints were assayed with an enzyme-linked immunosorbent assay (ELISA) system, the concentration of PGP 9.5 tended to be elevated in osteochondrosis dissecance, inflammatory arthropathy and intra-articular fracture, among which a statistically significant elevation was recognizable between the intra-articular fracture and the control. Thus, this study demonstrated the possibility that PGP 9.5, derived from synovial lining cells, may be a new biochemical marker for arthritic disorders of the horse.

Animals↗

PubMed2000

Inhibition of adjuvant-induced inflammatory hyperalgesia in rats by local injection of neurotrophin-3.

The induction of nerve growth factor (NGF) in inflammatory tissue has been shown to be involved in hyperalgesia. In the present study, the role of neurotrophin-3 (NT-3) in the regulation of inflammatory hyperalgesia was analyzed. Inflammatory hyperalgesia was induced by intraplantar injection of complete Freund's adjuvant (CFA) to the rat hind paw. NT-3 levels in the plantar skin were much higher than NGF levels (1.24 and 0.14 ng/g tissue, respectively) before CFA injection, but decreased significantly 6 h to 48 h after the injection while NGF was markedly induced at 6 h but decreased thereafter. When 1 microg of NT-3 was locally injected at 5 h after CFA injection at the time NT-3 levels decreased, hyperalgesia was reversed transiently but specifically. These results suggest an inhibitory role of NT-3 in the regulation of pain sensitivity.

Animals↗