Biomedical subjects

Yasushi Watanabe

Publications and source records attributed to Yasushi Watanabe.

15 recordsLinked to original sources

PubMed2006

[Utility of axial images in an early Alzheimer disease diagnosis support system (VSRAD)].

In recent years, voxel-based morphometry (VBM) has become a popular tool for the early diagnosis of Alzheimer disease. The Voxel-Based Specific Regional Analysis System for Alzheimer's Disease (VSRAD), a VBM system that uses MRI, has been reported to be clinically useful. The able-bodied person database (DB) of VSRAD, which employs sagittal plane imaging, is not suitable for analysis by axial plane imaging. However, axial plane imaging is useful for avoiding motion artifacts from the eyeball. Therefore, we created an able-bodied person DB by axial plane imaging and examined its utility. We also analyzed groups of able-bodied persons and persons with dementia by axial plane imaging and reviewed the validity. After using the DB of axial plane imaging, the Z-score of the intrahippocampal region improved by 8 in 13 instances. In all brains, the Z-score improved by 13 in all instances.

Alzheimer Disease↗

PubMed2006

[Examination of an imaging method in early Alzheimer disease diagnosis support system (VSRAD)].

The use of voxel-based morphometry (VBM) has recently become a popular tool for the early diagnosis of Alzheimer disease. The Voxel-Based Specific Regional Analysis System for Alzheimer's Disease (VSRAD) is a clinically useful VBM that employs MRI. However, there has been insufficient information about the influence of the image pickup apparatus and imaging conditions in terms of the value calculated by the sensitivity correction. We therefore reviewed this problem in a volunteer who provided consent. We were able to confirm reproducibility under the same conditions. When changing the image pickup apparatus and conditions, the average Z-score of 0.18+/-0.21 became larger, and the change in Z-score increased when imaging was done in the axial plane. Further, the average Z-score of 0.06+/-0.21 for sensitivity correction use was high on average by 0.19+/-0.16 for phased-array uniformity enhancement (PURE) and low for surface coil intensity correction (SCIC).

Adult↗

PubMed2006

Synthesis of a glycosylated peptide thioester by the Boc strategy and its application to segment condensation.

The synthesis of a chitobiosylated peptide thioester by the t-butoxycarbonyl (Boc) strategy is demonstrated. Boc-Asn carrying benzyl-protected chitobiose was introduced during application of the Boc mode solid-phase method. HF treatment of the resulting protected peptide resin gave the desired chitobiosylated peptide thioester. This thioester was used to prepare the peptide sequence derived from extracellular matrix metalloproteinase inducers (emmprin) (34-94), (34-118) and (22-118) by the thioester segment condensation method. The conformation of these glycopeptides is characterized by circular dichroism (CD) spectral measurement.

Amino Acid Sequence↗

PubMed2005

Physicochemical characterization of the reassembled dimer of an integral membrane protein OmpF porin.

The in vitro reassembled species of OmpF porin, which was renatured from its denatured monomer using n-octyl-beta-D-glucopyranoside, was characterized by low-angle laser light scattering photometry, circular dichroism spectroscopy and synchrotron radiation small-angle X-ray scattering measurements. The light scattering measurement reconfirmed that the reassembled species was the dimer of the protein. Circular dichroism spectra of the reassembled dimer showed a native-like beta-structure. A small-angle X-ray scattering measurement indicated that the size of the reassembled dimer was nearly equal to that of the native trimer under the present experimental conditions. In a thermal denaturation experiment followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the reassembled dimer was less stable than the native trimer.

Dimerization↗

PubMed2004

Utilization of low-field MR scanners.

The evident advantage of high-field MR (magnetic resonance) scanners is their higher signal-to-noise ratio, which results in improved imaging. While no reliable efficacy studies exist that compare the diagnostic capabilities of low- versus high-field scanners, the adoption and acceptance of low-field MRI (magnetic resonance imaging) is subject to biases. On the other hand, the cost savings associated with low-field MRI hardware are obvious. The running costs of a non-superconductive low-field scanner show even greater differences in favor of low-field scanners. Patient anxiety and safety issues also reflect the advantages of low-field scanners. Recent technological developments in the realm of low-field MR scanners will lead to higher image quality, shorter scan times, and refined imaging protocols. Interventional and intraoperative use also supports the installation of low-field MR scanners. Utilization of low-field systems has the potential to enhance overall cost reductions with little or no loss of diagnostic performance.

Cost-Benefit Analysis↗

PubMed2004

[Distinguishing between occluded and low-flow vessels with PROPELLER DWI sequence: a phantom study].

PURPOSE: To evaluate the ability of periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging (PROPELLER DWI) to distinguish between vessel occlusion and slow flow. MATERIALS AND METHODS: Using a flow phantom with various velocities (1.37 to 11.1 cm/s), the signal-intensity ratios of the phantom, with the intensity of no flow as baseline, were measured using the following imaging sequences: PROPELLER DWI, spin-echo T1-weighted imaging (SE T1WI), fast-spin-echo T2-weighted imaging (FSE T2WI), two-dimensional phase-contrast imaging (2D PC), and two-dimensional time-of-flight imaging (2D TOF). The b-factor of PROPELLER DWI was varied from 0 to 1000 s/mm(2). The velocity encoding of 2D PC was varied from 2 to 30 cm/s. RESULTS: At the lowest flow velocity (1.37 cm/s) , the signal-intensity ratio was 0.0075 for PROPELLER DWI (b-factor=1000 s/mm(2)), 1.8 for SE T1WI, 0.67 for FSE T2WI, 11 for 2D PC (velocity encoding=2 cm/s), and 1.4 for 2D TOF. The signal-intensity ratio was smallest for PROPELLER DWI, even when the reciprocals of the signal-intensity ratio of 2D PC or 2D TOF were considered. CONCLUSION: The results indicate that PROPELLER DWI provides the best signal intensity-ratio between vessel occlusion and slow flow. Although DWI with single-shot echo-planar imaging (EPI) or multi-shot EPI may have similarly high sensitivity for slow flow, these sequences do not have high spatial resolution or robustness to susceptibility artifacts. PROPELLER DWI would be a better choice for distinguishing between occluded and low-velocity arteries in the skull base or parasellar regions.

Blood Flow Velocity↗

PubMed2004

[Imaging characteristics of PROPELLER T2-weighted imaging].

As the PROPELLER sequence is a combination of the radial scan and fast-spin-echo (FSE) sequence, it can be considered an FSE sequence with a motion correlation. However, there are some differences between PROPELLER and FSE owing to differences in k-space trajectory. We clarified the imaging characteristics of PROPELLER T2-weighted imaging (T2WI) for different parameters in comparison with usual FSE T2WI. When the same parameters were used, PROPELLER T2WI showed a higher signal-to-noise ratio (SNR) and lower spatial resolution than usual FSE. Effective echo time (TE) changed with different echo train lengths (ETL) or different bandwidths on PROPELLER, and imaging contrast changed accordingly to be more effective.

Artifacts↗

PubMed2004

[Relations between clinical subtypes of Mycobacterium avium pulmonary disease and polyclonal infections detected by IS1245 based restriction fragment length polymorphism analysis].

INTRODUCTION: The epidemiology of Mycobacterium avium-intracellulare (MAC) infections has not been completely defined. Recently some reports presented polyclonal MAC infections. The purpose of this study was to reveal the clonal diversity of Mycobacterium avium isolates and the relation between clinical subtype of lung disease and polyclonal infection. METHODS: We categorized pulmonary Mycobacterium avium infection to three clinical subtypes, tuberculosis like type, bronchiectasis with preexisting tuberculosis type and nodular bronchiectasis type. Mycobacterium avium isolates of 11 patients were studied for their heterogeneity using IS1245 based RFLP analysis. The insertion sequence IS1245 is repetitive element identified only in Mycobacterium avium. Standard method of IS1245 based RFLP analysis has been proposed as a suitable technique for typing of Mycobacterium avium isolates for epidemiological and taxonomic studies. At least three distinct colonies were subcultured to single clone. The subclones of the isolates were analyzed by IS1245 based RFLP technique and some subclones were also examined by antimicrobial susceptibility test. RESULTS: Two of three patients of tuberculosis like type were considered to be monoclonal infection because only a single genotype was identified. And only one of four patients of bronchiectasis with preexisting tuberculosis type was considered to be polyclonal infection despite of long-term observation. Although isolates were collected in two or more occasions in clinical course over one year period, only a single genotype was observed in two patients. In contrast, three of four patients of nodular bronchiectasis type had multiple genotypes. Isolates recovered from patients with monoclonal infection pattern following long-term treatment with clarithromycin monotherapy became resistant to clarithromycin. In contrast, three strains derived from one nodular bronchiectasis patient were susceptible to clarithromycin despite of long-term chemotherapy including clarithromycin. The susceptibility patterns of the other drugs were also apparently different. Strain conversion due to repeated polyclonal infection was considered. These results of the antimicrobial susceptibility test supported clonal diversity of the Mycobacterium avium infection. DISCUSSION: IS1245 based RFLP analysis possesses a discriminatory power between the isolates on clonal level. This study demonstrates that polyclonal infections are common in nodular bronchiectasis type and monoclonal infections are common in tuberculosis like type and bronchiectasis with preexisting tuberculosis type. And not only simultaneous polyclonal infection but also repeated polyclonal infection were observed in a nodular bronchiectasis type patient. Drug susceptibility test showed long-term chemotherapy including clarithromycin could change the susceptibility of clarithromycin to resistant in patients with monoclonal infection. In contrast patients with repeated polyclonal infection pattern would avoid drug resistance because of strain conversion. This multiple susceptibility patterns identified in this study would not have been detected by the standard susceptibility test without subculture. And we also need the treatment strategy considering the polyclonal infection. CONCLUSIONS: Polyclonal infections are considered to be common in pulmonary Mycobacterium avium infection, especially nodular bronchiectasis type. Clonal diversity of Mycobacterium avium infection is an important factor to perform chemotherapy and drug susceptibility test.

Adolescent↗

PubMed2004

[Molecular epidemiological analysis by IS1245-based restriction fragment length polymorphism typing on cases with pulmonary Mycobacterium avium disease observed in the same family].

INTRODUCTION: Mycobacterium avium-intracellulare complex (MAC) has become one of major human pathogens, however, its routes of transmission and environmental reservoirs causing human infection were not yet elucidated. We reported three families affected by pulmonary Mycobacterium avium (M. avium) disease. Previous reports on MAC diseases observed in the same family were very rare. The purposes of this study were to investigate whether the infected M. avium was the same strain among cases in the same family and to examine the possibility of human-to-human transmission, or infection from exposure to a common environmental reservoir. METHODS: M. avium isolates from nine cases of three families were examined by DNA polymorphism based typing technique, restriction fragment length polymorphism (RFLP) analysis using insertion sequence IS1245 as a probe, to type the strains. Some isolates were subcultured to a single clone. RESULTS: All strains isolated from cases in the same family showed different patterns by the RFLP analysis. And not only simultaneous polyclonal infection but also repeated polyclonal infections were observed in some patients. DISCUSSION: The results suggest importance of underlying anti-mycobacterial immunological impairment and defects of local defense rather than virulence of infected strains as the pathogenesis of pulmonary M. avium disease.

Aged↗

PubMed2003

Acute pyogenic sacroiliitis without predisposing conditions.

STUDY DESIGN: Clinical and imaging findings of patients diagnosed with pyogenic sacroiliitis were retrospectively analyzed. OBJECTIVES: To characterize the clinical and magnetic resonance features of patients with acute pyogenic sacroiliitis without the usually known predisposing conditions and to investigate the diagnostic value of magnetic resonance imaging in detecting the early stages of pyogenic sacroiliitis. SUMMARY OF BACKGROUND DATA: Pyogenic sacroiliitis is relatively uncommon, and accurate diagnosis is frequently delayed due to lack of awareness by clinicians and nonspecific clinical presentation. There have been few reports that have evaluated the clinical features of acute pyogenic sacroiliitis and investigated the diagnostic capabilities of magnetic resonance imaging in detecting pyogenic sacroiliitis in the early stages. METHODS: The clinical data of 9 patients (6 male, 3 female; average age 27.3 years) diagnosed with acute pyogenic infection of the sacroiliac joint were retrospectively analyzed. Magnetic resonance images as well as computed tomography of the sacroiliac joints were available in all cases. Seven of the patients underwent 99mtechnetium bone scans. RESULTS: All patients showed positive findings on magnetic resonance images, whereas 99mtechnetium bone scans were positive in six of seven patients. Eight patients responded well to treatment with intravenous antibiotic therapy, whereas one patient required debridement of the sacroiliac joint following conservative treatment. CONCLUSIONS: Both magnetic resonance imaging and technetium bone scanning are sensitive for localizing occult sites of bone inflammation. Magnetic resonance imaging may provide more useful information than bone scanning by screening for abnormalities in the sacroiliac joint region. With prompt appropriate antibiotic therapy, clinical improvement of patients can be expected.

Acute Disease↗

PubMed2003

Complete heart block resulting from quadricuspid aortic valve penicillin-resistant pneumococcal endocarditis: a case report.

A 62-year-old woman was referred to hospital to be treated for complete heart block with syncope. A quadricuspid aortic valve without vegetation and aortic valve regurgitation (AR) were observed by transesophageal echocardiography. Blood culture showed penicillin-resistant Streptococcus pneumoniae. The patient received a permanent pacemaker implantation (VDD type) and was given antibiotics. Although infection improved, heart failure was not improved because AR hemodynamic changes became worse. An aortic valve replacement was performed using a prosthesis on the 26th day of hospitalization. The patient recovered and was discharged.

Aortic Valve↗

PubMed2003

[Indication and practice of pinning for fractures].

Advantages and disadvantages of pinning for fractures are mentioned and three ways of pinning are discussed. Pinning cases of fractures of the lower end of the humerus in Children are presented and the usefulness of pinning was shown.

English Abstract↗

PubMed2002

Characterization of the refolding and reassembly of an integral membrane protein OmpF porin by low-angle laser light scattering photometry coupled with high-performance gel chromatography.

The refolding and reassembly of an integral membrane protein OmpF porin denatured in sodium dodecylsulfate (SDS) into its stable species by the addition of n-octyl-beta-D-glucopyranoside (OG) have been studied by means of circular dichroism (CD) spectroscopy and low-angle laser light scattering photometry coupled with high-performance gel chromatography. The minimal concentration where change in the secondary structure was induced by the addition of OG was found to be 6.0 mg/ml in CD experiments. A species unfolded further than the SDS-denatured form of this protein was observed at an early stage (5-15 min) of refolding just above the minimal OG concentration. In addition, the CD spectrum of protein species obtained above the minimal OG concentration showed that the protein is composed of a beta-structure which is different from the native structure of this protein. In light scattering experiments, no changes in molecular assemblies were observed when the OG concentration was below its minimal refolding concentration determined by CD measurements. Above the minimal concentration, a compact monomeric species was observed when denatured OmpF porin was incubated for 5 min at 25 degrees C in a refolding medium containing 1 mg/ml SDS and 7 mg/ml OG, and then injected into columns equilibrated with the refolding medium. After an incubation of 24 h before injection into the columns, predominant dimerization of this protein was observed in addition to incorrect aggregation.

Chromatography, High Pressure Liquid↗

PubMed2002

Effect of various mild surfactants on the reassembly of an oligomeric integral membrane protein OmpF porin.

Reassembly of OmpF porin from its denatured monomer into the sodium dodecyl sulfate-resistant species was investigated by using 27 kinds of mild surfactants. Polyethyleneoxide-type surfactants with a hydrophilic-lipophilic balance value of 10.8-14.6 induced the trimerization of denatured OmpF porin. Dimerization and trimerization were induced by non-polyethyleneoxide-type mild surfactants that are generally used for membrane protein solubilization. The dependence of surfactant concentrations on reassembly was estimated to obtain a minimal concentration required for the reassembly of the protein. Extensive reassembly (to approximately 85% yield) into dimer (a putative assembly intermediate) was observed at a protein concentration of 0.05 mg/ml in 7 mg/ml n-octyl-beta-D-glucopyranoside and 1 mg/ml sodium dodecyl sulfate. This condition will be useful for the studies of the dimer and dimerization of OmpF porin. The role of mixed micelle system on the protein renaturation was discussed.

Chromatography, Gel↗

PubMed2002

[Evaluation of PROPELLER MR imaging: preliminary experiences].

Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction (PROPELLER) MR imaging (MRI) has a unique ability to correct motion artifacts and is expected to be useful in diffusion-weighted MRI. This article describes preliminary experiences with PROPELLER MRI. PROPELLER uses a radial scan variation of the fast spin-echo sequence and it shows much less spatial deterioration than the echo-planar imaging sequence. To determine the optimal parameters of this technique, we calculated the signal intensities of phantoms and brains in various settings. PROPELLER MR examinations were also performed in 66 patients for clinical use. PROPELLER MRI appears to be a promising and useful technique.

Artifacts↗