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Hiroki Yamamoto

Publications and source records attributed to Hiroki Yamamoto.

At least 19 recordsLinked to original sources
PubMed2006

Toward a common circle: interhemispheric contextual modulation in human early visual areas.

Humans can readily and effortlessly perceive a rich, stable, and unified visual world from a complex visual scene. Yet our internal representation of a visual object appears to be sparse and fragmented. How and where in the brain are such fragmented representations organized into a whole percept? Recent studies have accumulated evidence that some global feature integration is mediated at the early stage of visual processing. However, the spatial operating range of the integration still remains unclear. The present human functional magnetic resonance imaging study provides support that the global integration process in early visual areas, including even the primary visual area V1, is mediated beyond the separated projection of visual hemifields from right and left sides of the fixation to the visual cortex of the contralateral cerebral hemisphere. Retinotopic neural responses corresponding to a visual target were significantly enhanced when another target was simultaneously presented at the point-symmetrical position in the nonassociated visual field quadrant. The result makes a convincing case that the contextual effects involve feedback from higher areas, because there are no direct callosal connections that allow such interhemispheric contextual modulation. This enhancement from the ipsilateral hemifield may help rapid position-and-size-invariant detection of a circular pattern, which may be special among visual structures because of its ubiquity in natural scenes. Early visual areas as well as higher ones may play a more essential role in perceiving the unity of the real world than previously thought.

Adult↗
PubMed2006

In vivo performance of two different hydroxyapatite coatings on titanium prepared by discharging in electrolytes.

This study reports a discharging method for bone-like carbonated HA (cHA)-coating (Ca/P 1.71) and stoichiometric HA (sHA)-coating (Ca/P 1.67) with micrometer order thicknesses on titanium plates, using modified body fluid and acidic calcium phosphate solutions, respectively. In vivo histological performance of the HA coatings prepared by discharging in electrolytes was evaluated. Bone-contact indexes of HA coatings were measured microscopically. Additionally, bone-coating interface was analyzed by scanning electron microscopy and the use of an electron probe microanalyzer. Results demonstrated that there was no significant difference in contact index between HA coatings. However, the cHA coating was practically replaced by immature bone, and the titanium metal substrate was directly connected to the bone structure whereas the sHA coating layer remained and was partially detached from the titanium metal substrate. Since detached coating particles are pathogens, and can cause peri-implantitis, the cHA coating was more favorable than the sHA coating even if contact index was equivalent to that of the sHA coating. It is thought that coating thickness and chemical composition of coatings are important for biological stability of implants. In conclusion, since bone-like thin cHA coating showed high osteoconductivity and bone replacement, bone-like HA is superior to sHA coating for use in dental implants.

Coated Materials, Biocompatible↗
PubMed2006

Identification of the lumbar intervertebral level using ultrasound imaging in a post-laminectomy patient.

A spinal block was performed in a post-laminectomy patient, using both ultrasound imaging and X-ray imaging. Ultrasound imaging clearly identified the L3/4 intervertebral level, the spinal canal, the corpus vertebrae, and the dura mater. Using ultrasound imaging, we measured the distance from the skin surface to the dura mater (39 mm). A 25-G needle for the spinal block was accurately advanced into the spinal canal with the use of X-ray imaging (43 mm from the skin to the subarachnoid space). We report here that ultrasound imaging was useful for performing a spinal block in a post-laminectomy patient in whom there was anatomical change around the spine.

Aged, 80 and over↗
PubMed2006

Analysis of a soldered wire burnt in a fire.

Fire investigators frequently encounter electrical wires with melted ends at fire scenes, which can provide useful information on the cause and development of the fire even when the melted ends result from the fires. A bead on a melted end of a wire was found in the area of origin of a massive fire that lasted for nearly a whole day, devastating a factory. The bead appeared to be the end of a wire soldered to a terminal. X-ray analysis showed that the bead is a tin-copper alloy. Although regular tin-lead solder was used in the factory, lead was not detected. This contradictory result stood in the way of fire investigation. Therefore, an unused wire soldered with tin-lead solder was heated in an electric furnace at 500 degrees C for 3 h for further examination. X-ray analysis of this wire showed that copper can be alloyed with tin while losing lead in a long-term heat in a fire.

Journal Article↗
PubMed2006

A new D,L-endopeptidase gene product, YojL (renamed CwlS), plays a role in cell separation with LytE and LytF in Bacillus subtilis.

A new peptidoglycan hydrolase, Bacillus subtilis YojL (cell wall-lytic enzyme associated with cell separation, renamed CwlS), exhibits high amino acid sequence similarity to LytE (CwlF) and LytF (CwlE), which are associated with cell separation. The N-terminal region of CwlS has four tandem repeat regions (LysM repeats) predicted to be a peptidoglycan-binding module. The C-terminal region exhibits high similarity to the cell wall hydrolase domains of LytE and LytF at their C-terminal ends. The C-terminal region of CwlS produced in Escherichia coli could hydrolyze the linkage of d-gamma-glutamyl-meso-diaminopimelic acid in the cell wall of B. subtilis, suggesting that CwlS is a d,l-endopeptidase. beta-Galactosidase fusion experiments and Northern hybridization analysis suggested that the cwlS gene is transcribed during the late vegetative and early stationary phases. A cwlS mutant exhibited a cell shape similar to that of the wild type; however, a lytE lytF cwlS triple mutant exhibited aggregated microfiber formation. Moreover, immunofluorescence microscopy showed that FLAG-tagged CwlS was localized at cell separation sites and cell poles during the late vegetative phase. The localization sites are similar to those of LytF and LytE, indicating that CwlS is involved in cell separation with LytF and LytE. These specific localizations may be dependent on the LysM repeats in their N-terminal domains. The roles of CwlS, LytF, and LytE in cell separation are discussed.

Bacillus subtilis↗
PubMed2006

[Cognitive aging mechanism of signaling effects on the memory for procedural sentences].

The aim of this study was to clarify the cognitive aging mechanism of signaling effects on the memory for procedural sentences. Participants were 60 younger adults (college students) and 60 older adults. Both age groups were assigned into two groups; half of each group was presented with procedural sentences with signals that highlighted their top-level structure and the other half with procedural sentences without them. Both groups were requested to perform the sentence arrangement task and the reconstruction task. Each task was composed of procedural sentences with or without signals. Results indicated that signaling supported changes in strategy utilization during the successive organizational processes and that changes in strategy utilization resulting from signaling improved the memory for procedural sentences. Moreover, age-related factors interfered with these signaling effects. This study clarified the cognitive aging mechanism of signaling effects in which signaling supports changes in the strategy utilization during organizational processes at encoding and this mediation promotes memory for procedural sentences, though disuse of the strategy utilization due to aging restrains their memory for procedural sentences.

Adolescent↗
PubMed2006

[A case of primary choriocarcinoma of the mediastinum in a Japanese woman].

A 32-year-old Japanese woman was referred to our hospital complaining of non-productive cough and dyspnea when in a dorsal position. Physical examination revealed left cervical lymph node swelling. Laboratory data showed HCG 17,700mIU/ml, betaHCG 130ng/ml, CYFRA 104ng/ml, AFP<2.0ng/ml, and LDH 802IU/l. A chest radiograph showed a giant mass shadow in the left hilum and many round mass shadows in both lung fields. Chest CT showed a mass shadow in the anterior mediastinum and many round mass shadows in both lung fields. There was no abnormality on abdominal and pelvic CT. A CT-guided transcutaneous lung biopsy specimen obtained from a mass in the left lower lobe revealed necrotized portions and atypical cells which were positive for HCG. We diagnosed primary choriocarcinoma of the mediastinum. The patient received 4 courses of the standard BEP regimen, resulting in partial response. This is the first reported case of primary choriocarcinoma of the mediastinum in a Japanese woman.

Adult↗
PubMed2005

Progestins and estrogens and Alzheimer's disease.

Sex-specific incidence rates for Alzheimer's disease (AD) are higher in women than men. Many fundamental researches and some clinical investigations have reported therapeutic and preventive effects of estrogens on AD. But WHIMS [S.A. Shumaker, C. Legault, S.R. Rapp, L. Thal, R.B. Wallace, J.K. Ockene, S.L. Hendrix, B.N. Jones IIIrd, A.R. Assaf, R.D. Jackson, J.M. Kotchen, S. Wabertheil-Smoller, J. Wactawsk-Wende, WHIMS investigators, Estrogen plus progestin and the incidence of dementia and mild cognitive impairment in postmenopausal women. The women's health initiative memory study: a randomized controlled trial, JAMA 289 (2003) 2651-2662], which used daily continuous hormone replacement therapy (HRT), reported that the hazard ratio of the HRT for probable dementia was 2.05. Effect of progestins, and continuous (not cyclically) HRT, even only with estrogen should be reconsidered. In our clinical study, conjugated equine estrogen (CEE) alone showed good changes of psychiatric tests for AD on the 3rd week, but addition of medroxyprogesterone acetate (MPA) or norethindrone since 4th week suppressed these tests. Using human umbilical vein epithelial cell (HUVEC), levonorgestrel (LNG), norethindrone acetate (NETA), MPA increased intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-secretin but dienogest (DNG) showed no effect. In vitro flow system, estradiol (E2), suppressed adhesion of white cell, but LNG, NETA, MPA increased the adhesions. DNG showed less effect. Non-feminizing estrogen J 861, which has delta8,9 double bond and straight in its structure and has less effect on sexual organs. J 861 has shown ameliorative effects on central nervous system (CNS) (increasing of cholineacetyltransferase immunoreactive cells in substantia innominata (SI), etc.) like E2. More investigations about progestins and estrogens and AD should be done.

Alzheimer Disease↗
PubMed2005

Functional analysis of the YvrGHb two-component system of Bacillus subtilis: identification of the regulated genes by DNA microarray and northern blot analyses.

YvrGHb is a novel two-component system in Bacillus subtilis. The yvrG and yvrHb genes are considered to encode sensor kinase and response regulator respectively. We found that the YvrGHb system positively regulates the 7 transcriptional units (wprA, wapA-yxxG, dltABCDE, sunA, sunT-bdbA-yolJ-bdbB, yvrI-yvrHa, and sigX-rsiX), and negatively regulates the lytABC operon. wprA, wapA, lytB, and lytC encode the main cell surface proteins of B. subtilis. Furthermore, SigX [extracytoplasmic function sigma factor (ECF sigma factor)] relating to the cell surface homeostatic functions, was regulated by this system. The yvrGHb null mutant showed the unusual autolysis and higher susceptibility to the four kinds of antibiotics (aztreonam, cefepime, bacitracin, and fosfomycin). These results indicate that the YvrGHb system is important to maintain the overall state of the cell surface through transcriptional regulation.

Autolysis↗
PubMed2005

[Evaluation by undergraduate medical students of clinical clerkships in the department of anesthesiology--comparison with the evaluation in previous fiscal year].

BACKGROUND: Clinical Clerkships in the Department of Anesthesiology were evaluated by undergraduate medical students and compared with other clinical departments and those of previous fiscal year 2003. METHODS: Questionnaire surveys by 5 step Likert measure were conducted to ask the students for the evaluation of each department or division, and formative evaluation was performed after the all clerkships. The questionnaire consisted of 12 questions on 1) orientation, 2) learning chances and provision of teaching materials, 3) feedback, learning promotion and teaching attitude, 4) coordination of human relationship between medical staff and students, and 5) overall evaluation of teacher's physician. RESULTS: The average score of our department was 4.40 (mean, 5 th grade of all 26 departments/divisions), and the score of the question on provision of medical practice (4.71) was the best among the all departments/divisions. The evaluation grading was rather low for the question on chance for physical examinations (3.80). CONCLUSIONS: Reevaluation of the educational program in our department based on the results of the survey is essential for improvement of the program, and further provision of chances, especially for physical examinations, is also needed for undergraduate students in the program by including palliative medical care program.

Anesthesiology↗
PubMed2005

[A trial of introduction of portfolio to elective clinical clerkship in anesthesiology].

BACKGROUND: Portfolio as one of the educational techniques was introduced to elective clinical clerkship (CC) of Anesthesiology in Sapporo Medical University School of Medicine in the 2003 fiscal year. METHODS: Fourteen medical students who elected Anesthesiology CC for 3 weeks had a duty to study and feed back their CC everyday by writing portfolio, and the attending checked and fed back their portfolio every week. At the end of the CC, questionnaire surveys by 5 step Likert measure and group discussion were conducted to determine the evaluation by students of the portfolio in Anesthesiology CC. RESULTS: The average score of the questionnaire surveys was high(4.78). However, the scores of usefulness of the portfolio for feedback to student's attitude and to good relationship among medical staff were relatively low (4.6 and 4.4, respectively). CONCLUSIONS: The use of a portfolio as a educational technique in elective CC seems to be useful, and further education to chief/senior medical staff for feedback to student's attitude and other kinds of educational techniques for feedback to good relationship among medical staff are needed.

Anesthesiology↗
PubMed2004

Systematic analysis of SigD-regulated genes in Bacillus subtilis by DNA microarray and Northern blotting analyses.

The SigD-regulated genes in Bacillus subtilis were systematically analyzed by comparing the pattern of transcripts derived from wild-type cells with those from sigD mutant cells using DNA microarray technology. One hundred and fifty-eight genes were found to be SigD-dependent candidates, 46 of which being known SigD-regulated genes. Northern blot analysis revealed that 18 of the remaining genes were SigD-dependent. The SigD consensus sequence was newly identified in the upstream regions of nine operons (11 genes): ybdO, yfmT-yfmS, hemAT, yjcP-yjcQ, yjfB, ylqB, yoaH, yscB and yxkC, and the other seven genes were assumed to be indirectly affected by a SigD mutation. Furthermore, yviE-yviF are likely to be SigD-dependent genes, because three independent sets of array data for yviE and yviF indicated they are SigD-dependent, and these genes are neighbors of flgL and hag transcribed by SigD RNA polymerase.

Bacillus subtilis↗
PubMed2004

Characterization of a new Bacillus subtilis peptidoglycan hydrolase gene, yvcE (named cwlO), and the enzymatic properties of its encoded protein.

Bacillus subtilis yvcE (named cwlO) encodes a polypeptide consisting of 473 amino acid residues, and the N-terminal region contains a putative signal sequence and the C-terminal region exhibits high similarity to those of the NLPC/P60 superfamily (DL-endopeptidase family II). Northern blotting and cwlO-lacZ fusion analyses indicated that the cwlO gene is expressed as a monocistronic mRNA during the vegetative growth phase. The C-terminal region of CwlO was cloned into an Escherichia coli histidine-tagged vector and the protein, C-CwlO-6His, was produced in E. coli. The purified C-CwlO-6His protein exhibited cell wall hydrolase activity and the substrate bond specificity indicated that it is a DL-endopeptidase. The cell wall hydrolytic activity which seems to be derived from partially degraded CwlO (YvcE) was found in the culture supernatant of B. subtilis, but not in the cell wall binding fraction. The disruption of cwlO did not result in any difference in cell growth, morphology, or motility.

Journal Article↗
PubMed2004

Characterization of a polysaccharide deacetylase gene homologue (pdaB) on sporulation of Bacillus subtilis.

The predicted amino acid sequence of Bacillus subtilis ybaN (renamed pdaB) exhibits high similarity to those of several polysaccharide deacetylases. Northern hybridization analysis with sporulation sigma mutants indicated that the pdaB gene is transcribed by EsigmaE RNA polymerase and negatively regulated by SpoIIID. The pdaB mutant was deficient in spore formation. Phase- and electron microscopic observation showed morphological changes of spores in late sporulation periods. The pdaB spores that had lost their viability were empty. Moreover, GFP driven by the promoter of the sspE gene was localized in the forespore compartment for the wild type, but was localized in both the mother cell and forespore compartments for phase-gray/dark forespores of the pdaB mutant. This indicates that GFP expressed in the forespores of the mutant leaks into the mother cells. Therefore, PdaB is necessary to maintain spores after the late stage of sporulation.

Amidohydrolases↗
PubMed2004

Root nodule Bradyrhizobium spp. harbor tfdAalpha and cadA, homologous with genes encoding 2,4-dichlorophenoxyacetic acid-degrading proteins.

The distribution of tfdAalpha and cadA, genes encoding 2,4-dichlorophenoxyacetate (2,4-D)-degrading proteins which are characteristic of the 2,4-D-degrading Bradyrhizobium sp. isolated from pristine environments, was examined by PCR and Southern hybridization in several Bradyrhizobium strains including type strains of Bradyrhizobium japonicum USDA110 and Bradyrhizobium elkanii USDA94, in phylogenetically closely related Agromonas oligotrophica and Rhodopseudomonas palustris, and in 2,4-D-degrading Sphingomonas strains. All strains showed positive signals for tfdAalpha, and its phylogenetic tree was congruent with that of 16S rRNA genes in alpha-Proteobacteria, indicating evolution of tfdAalpha without horizontal gene transfer. The nucleotide sequence identities between tfdAalpha and canonical tfdA in beta- and gamma-Proteobacteria were 46 to 57%, and the deduced amino acid sequence of TfdAalpha revealed conserved residues characteristic of the active site of alpha-ketoglutarate-dependent dioxygenases. On the other hand, cadA showed limited distribution in 2,4-D-degrading Bradyrhizobium sp. and Sphingomonas sp. and some strains of non-2,4-D-degrading B. elkanii. The cadA genes were phylogenetically separated between 2,4-D-degrading and nondegrading strains, and the cadA genes of 2,4-D degrading strains were further separated between Bradyrhizobium sp. and Sphingomonas sp., indicating the incongruency of cadA with 16S rRNA genes. The nucleotide sequence identities between cadA and tftA of 2,4,5-trichlorophenoxyacetate-degrading Burkholderia cepacia AC1100 were 46 to 53%. Although all root nodule Bradyrhizobium strains were unable to degrade 2,4-D, three strains carrying cadA homologs degraded 4-chlorophenoxyacetate with the accumulation of 4-chlorophenol as an intermediate, suggesting the involvement of cadA homologs in the cleavage of the aryl ether linkage. Based on codon usage patterns and GC content, it was suggested that the cadA genes of 2,4-D-degrading and nondegrading Bradyrhizobium spp. have different origins and that the genes would be obtained in the former through horizontal gene transfer.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2004

[Evaluation by undergraduate medical students of clinical clerkships in the Department of Anesthesiology].

BACKGROUND: Clerkships for undergraduate clinical training were introduced in Sapporo Medical University School of Medicine in 2002. METHODS: Questionnaire surveys by 5 steps Likert measure were conducted by asking the students about the evaluation of each department or division, and overall evaluation was obtained after the clerkships. The questionnaire consisted of 12 questions on 1) orientation; 2) learning chances and provision of teaching materials; 3) feedback, learning promotion and teaching attitude; 4) coordination of human relationship between medical staff and students; and 5) overall evaluation of teacher's physician. RESULTS: The average score for our department was 4.30 (mean, 6th grade of all 26 departments/divisions), and the scores on provision of medical practice (4.69) and the overall teacher's physician grading (4.65) were the best among the all departments/divisions. The evaluation gradings were rather low on chances for medical and health care interviews (3.59); physical examinations (3.83); and description of medical record (3.73). CONCLUSIONS: Reevaluation of the educational program in our department based on the results of the survey is essential for improvement of the program, and further provision of chances, especially for medical interviews, physical examinations and description of medical record is also needed for undergraduate students in the program.

Anesthesiology↗