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Biomedical subjects

Y Yoshida

Publications and source records attributed to Y Yoshida.

At least 37 records · Page 2Linked to original sources
PubMed2005

Elucidation of the relationship between enzyme activity and internal motion using a lysozyme stabilized by cavity-filling mutations.

We investigated the activity and the internal motions of a stabilized mutant hen lysozyme (HEL) in which the residues M12 and L56 were mutated to L and F, respectively (LF mutant HEL). The result of the activity measurements against glycol chitin at various temperatures suggested that the temperature dependence of the activity of LF mutant HEL shifted to the high-temperature side compared with that of wild-type HEL. The detailed internal motions of LF mutant HEL in the absence and presence of a substrate analogue, (NAG)3, were examined by model-free analysis at 35 degrees C. The results showed that the internal motions of LF mutant HEL in the presence of (NAG)3 were drastically restricted compared with those in wild-type HEL. Our findings thus suggested that the mutation to the stabilized lysozyme restricted internal motions required for the enzymatic reaction.

Acetylglucosamine↗
PubMed2005

Supratentorial cerebral arteriovenous fistulas (AVFs) in children: review of 41 cases with 63 non choroidal single-hole AVFs.

PURPOSE: In this article we explore the various aspects of the supratentorial Single-Hole AVFs (ST AVFs) in children, focusing on their clinical features, angio-architecture, treatment indications and the role and results of endovascular management. MATERIALS AND METHODS: Among 1565 cases of brain AVMs seen at our neurovascular center, 620 cases were seen in the pediatric age group (<or= to 15 year-old) and 303/620 were non-Galenic brain AVMs. Among 52 brain AVFs found in children, we reviewed 41 pediatric patients with supratentorial single-hole cerebral AVFs (M/F=28/13) with a total of 63 AVFs. Mean age at presentation was 24 months. Four cases had their lesion diagnosed in utero without particular prognostic significance. 17 cases were multifocal with a total of 39 AVFs. The most common clinical presentation leading to diagnosis was cardiac sufficiency in (31.7%), epilepsy (24.4%), macrocrania (14.6%). Venous ectasia (87.8%) and pial venous stenosis (41.5%) were the most frequent angiographic features. There were 11 cases of Hemorrhagic Heriditary Telangiectasia (HHT1) (including two suspicious cases) among the 41 patients (26.8%) and among those 4 cases had single AVFs and 7 cases had multiple AVFs. RESULTS: Thirty-five children were treated in our institution: 34/35 by embolization alone, 1/35 by a combination of embolization and radiosurgery. 32/35 patients were treated with glue alone, 3/35 with coils (2/3 with glue also). A total of 57 separate lesions were treated. On clinical follow up (from 1985-2002, mean 4.2 years), 88.6% of patients proved to be either asymptomatic, improved from previous clinical symptoms or stabilized. 40% of patients had their lesion(s) already completely excluded. Post operative mortality was 5.6% (2/35), permanent neurological morbidity 3% (1/33). Twenty-six of these 33 patients (78.6%) were neurologically normal. 5/33 patients continue to have neurological symptoms or retardation. 2/33 patients died during follow up (1 ischemic stroke from Pulmonary AVF, 1 death despite partial embolisation). CONCLUSION: Cerebral arteriovenous fistulae are a rare disease, but not infrequently seen in neonates and infants with AVMs. In one fourth of these patients HHT is suspected to be present. The AVFs are always superficial and fed by pial (cortical) arteries. They seldom reveal a hemorrhagic event. They are similar to those encountered in the posterior fossa or spinal cord. Endovascular treatment using NBCA was the treatment modality chosen resulting in a high rate of success and allowing children to grow up normally with no hemorrhages on follow up and no new symptom other than those already present on admission.

Adolescent↗
PubMed2005

Micro-rotary fatigue of tooth-biomaterial interfaces.

The bonding effectiveness of restorative materials to tooth tissue is typically measured statically. Clinically tooth/composite bonds are however subjected to cyclic sub-critical loads. Therefore, in vitro fatigue testing of dental adhesives should predict better the in vivo performance of adhesives. The objective of this study was to determine the fatigue resistance of two representative adhesives, a self-etch and an etch&rinse adhesive, bonded to enamel and dentin. Therefore, tooth/composite interfaces were cyclically loaded using a miniaturized version of a rotating beam fatigue testing device. Subsequently, the load at which 50% of the specimens fail after 10(5) cycles, was determined as the median micro-rotary fatigue resistance (microRFR). For both adhesives, the microRFR was about 30-40% lower than the corresponding micro-tensile bond strength (microTBS) to both enamel and dentin. Analysis of the fracture surfaces by Feg-SEM revealed typical fatigue fracture patterns. It is concluded that resin/tooth interfaces are vulnerable to progressive damage by sub-critical loads, with the 3-step etch&rinse adhesive being more resistant to fatigue than the 2-step self-etch adhesive.

Adhesiveness↗
PubMed2005

What factors are associated with high plasma B-type natriuretic peptide levels in a general Japanese population?

There are few community-based epidemiologic studies that have dealt with risk factors for heart failure in non-Western populations. It has been reported that the measurement of plasma B-type natriuretic peptide (BNP) is useful for detecting patients with asymptomatic heart failure. To clarify the determinants of high plasma BNP level, the association of BNP with cardiovascular risk factors in community dwelling residents was examined. The plasma BNP levels were measured in 686 residents aged 35-69 years who received annual health check-up. The relationship of BNP to blood pressure, blood haemoglobin, serum cholesterol (total and high-density lipoprotein cholesterol), plasma glucose, electrocardiographic (ECG) findings, urinary salt excretion, and lifestyle factors (smoking and alcohol consumption) were cross-sectionally analysed. The plasma BNP geometric mean was 13.7 pg/ml. Both linear and logistic regression analyses indicated that the plasma BNP levels were positively associated with age, urinary salt excretion, higher blood pressure, high R-wave voltage in the 12-lead ECG (Minnesota Code 3-1 or 3-3), and female gender. Plasma BNP levels were inversely associated with blood haemoglobin levels. Gender-specific analysis showed similar results. However, plasma BNP did not correlate with other cardiovascular risk factors such as serum lipids.

Adult↗
PubMed2005

Surgical treatment for lung cancer with COPD based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD).

OBJECTIVE: The surgical indications for non-small cell carcinoma (NSCLC) with chronic obstructive pulmonary disease (COPD) are not well known. A classification of severity in COPD has been newly recommended by the US National Heart, Lung, and Blood Institute (NHLBI) and the World Health Organization (WHO). Therefore, based on this new system of classification, we review here a series of NSCLC patients with COPD who underwent lung resection at our hospital and attempt to identify the survival and morbidity of such patients. METHODS: We retrospectively reviewed the patients with NSCLC treated at our hospital between January 1994 and December 2002. Among these 640 patients, a curative approach was attempted in 50 with COPD (31 lobectomies, 11 segmentectomies, 8 bilobectomies). The patients were consequently divided into two groups (moderate group and severe group) according to the Global Iinitiative for Chronic Obstructive Lung disease (GOLD). Lung function was evaluated by FEV1 and FVC, and the survival rates were analyzed at 5 years. Postoperative morbidity was also compared between the two groups. RESULTS: FEV1 was 1.527 +/- 0.311 L in the moderate group compared with 1.025 +/- 0.224 L in the severe group ( p < 0.001). Postoperative decrease in FEV1 was lower compared to the predicted data of patients who underwent surgery for NSCLC with COPD. Postoperative pulmonary support such as mechanical ventilation or tracheotomy were necessary more frequently in the severe group. A significant difference was observed between the two groups in respiratory support ( p = 0.0102). Overall 5-year survival rate for NSCLC with COPD was 73.9 %, although there was no statistically significant difference between the moderate and severe groups in terms of survival. Lobectomy and segmentectomy show a remarkable advantage for the patients with bilobectomy, although this difference was not statistically significant. On the other hand, gender, degree of COPD, and histological type were shown to be not significant factors. Survival rate of these NSCLC patients with COPD were demonstrated to be comparable to those of the NSCLC patients without COPD in stages I and II. CONCLUSION: Stringent selection of candidates among NSCLC patients with a severe grade of COPD based on GOLD could be an acceptable and valuable approach compared to conventional patients without COPD, although NSCLC with severe COPD patients more frequently needed respiratory support.

Aged↗
PubMed2005

Effect of tacrolimus in a patient with pure red-cell aplasia.

A 78-year-old woman has suffered from pure red-cell aplasia (PRCA) associated with generalized myasthenia gravis and thymoma. Cyclosporin A (CyA) with corticosteroid increased numbers of erythroid cells in her bone marrow cells but she required monthly blood transfusions. Administration of tacrolimus as a substitution for CyA inhibited progression of anemia without the need for further blood transfusion. No serious side effects were observed. This case demonstrates that tacrolimus is another option of treatment for PRCA in patients who fail to respond to CyA.

Aged↗
PubMed2005

Isolated colonic hernia through the esophageal hiatus.

We report on a 75-year-old woman with an isolated colonic hernia through the esophageal hernia. The patient had suffered from cough, palpitation and dyspnea. A chest X-ray showed a colon loop gas in the mediastinum. Simultaneous barium swallow and enema showed the herniation of the only transverse colon into the mediastinum and displacement of the distal esophagus by the migrated colon. The patient underwent an open-mesh cruroplasty and a Hill's posterior gastropexy. The postoperative clinical course was uneventful. The patient has cessation of the symptoms. To our knowledge, there are only five reports presenting patients with isolated colonic hernia through the esophageal hiatus, including our case.

Aged↗
PubMed2005

Monomer-solvent phase separation in one-step self-etch adhesives.

One-step adhesives bond less effectively to enamel/dentin than do their multi-step versions. To investigate whether this might be due to phase separation between adhesive ingredients, we characterized the interaction of 5 experimental and 3 commercial self-etch adhesives with dentin using transmission electron microscopy. All adhesives were examined for homogeneity by light microscopy. Bonding effectiveness to dentin was determined with the use of a micro-tensile bond-strength protocol. The lower bond strength of the one-step adhesives was associated with light-microscopic observation of multiple droplets that disappeared slowly. Interfacial analysis confirmed the entrapment of droplets within the adhesive layer. The prompt disappearance of droplets upon application of a small amount of HEMA (2-hydroxyethyl methacrylate) or a HEMA-containing bonding agent, as well as the absence of droplets at the interface of all HEMA-containing adhesives, strongly suggests that the adhesive monomers separate from water upon evaporation of ethanol/acetone. Upon polymerization, the droplets become entrapped within the adhesive, potentially jeopardizing bond durability. This can be avoided by strong air-drying of the adhesive, thereby removing interfacial water and thus improving bonding effectiveness.

Acid Etching, Dental↗
PubMed2005

Hydrolytic stability of self-etch adhesives bonded to dentin.

Functional monomers chemically interact with hydroxyapatite that remains within submicron hybrid layers produced by mild self-etch adhesives. The functional monomer 10-MDP interacts most intensively with hydroxyapatite, and its calcium salt appeared most hydrolytically stable, as compared with 4-MET and phenyl-P. We investigated the hypothesis that additional chemical interaction of self-etch adhesives improves bond stability. The micro-tensile bond strength (muTBS) of the 10-MDP-based adhesive did not decrease significantly after 100,000 cycles, but did after 50,000 and 30,000 cycles, respectively, for the 4-MET-based and the phenyl-P-based adhesives. Likewise, the interfacial ultrastructure was unchanged after 100,000 thermocycles for the 10-MDP-based adhesive, while that of both the 4-MET- and phenyl-P-based adhesives contained voids and less-defined collagen. The findings of this study support the concept that long-term durability of adhesive-dentin bonds depends on the chemical bonding potential of the functional monomer.

Acid Etching, Dental↗
PubMed2004

Kink in the dispersion of layered strontium ruthenates.

We present detailed energy dispersions near the Fermi level along the high symmetry line GammaX on the monolayer and bilayer strontium ruthenates Sr2RuO4 and Sr3Ru2O7, determined by high-resolution angle-resolved photoemission spectroscopy. A kink in the dispersion is clearly shown for the both ruthenates. The energy position of the kink and the slope in the low-energy part near the Fermi level are almost identical between them, whereas the dispersion in the high-energy part varies, like the behavior of the kink for the cuprate superconductors.

Journal Article↗
PubMed2004

Family-based association study of schizophrenia with 444 markers and analysis of a new susceptibility locus mapped to 11q13.3.

Family-based linkage disequilibrium (LD) mapping has been suggested as a powerful and practical alternative to linkage analysis. We have performed a genome-wide LD survey of susceptibility loci for schizophrenia in a Japanese population. We first typed 119 schizophrenic pedigrees (357 individuals) using 444 microsatellite markers, and analyzed the data using the pedigree disequilibrium test. This analysis revealed 14 markers demonstrating significant transmission distortion. To corroborate these findings, the statistical methods were changed to the extended transmission disequilibrium test (ETDT), using 80 independent complete trios (schizophrenic proband and both parents), with 68 derived from initial pedigrees and 12 newly recruited trios. ETDT supported two markers for continued association, D11S987 on 11q13.3 (P = 0.00009) and D16S423 on 16p13.3 (P = 0.002). We scrutinized the most significant genomic locus on 11q11-13 by adding 26 new markers for analysis. Results of three-marker haplotype analysis in the region showed evidence of association with schizophrenia (most significant haplotype P = 0.0005, global P = 0.022). Although the present study may have missed other potential genomic intervals because of the sparse mapping density, we hope that it has identified promising anchor points for further studies to identify risk-conferring genes for schizophrenia in the Japanese population. In addition, we provide useful information on genomic LD structures in Japanese populations, which can be used for LD mapping of complex diseases.

Chromosome Mapping↗
PubMed2004

Posterior cranial fossa single-hole arteriovenous fistulae in children: 14 consecutive cases.

We report 14 consecutive children with 23 posterior cranial fossa arteriovenous fistula (AVF); six had multifocal lesions, involving the supratentorial brain in three and the spinal cord in one. There were two boys and four girls with a family history compatible with hereditary haemorrhagic telangiectasia. The diagnosis was made in infancy in eight cases and in a further six before the age of 12 years; mean age at diagnosis was 3.5 years. The male-to-female ratio was 1.8:1. Presenting features were macrocrania in four cases, haemorrhage or headache in three and nonhaemorrhagic neurological deficits or and cardiac overload in two. Dominant supply to the symptomatic fistula arose from the posterior inferior cerebellar artery in five cases, anterior inferior cerebellar artery in two and the upper basilar artery system in seven. All children were primarily treated by transarterial embolisation. We treated thirteen children (93%) by transarterial embolisation alone; one older child with a history of haemorrhage also underwent radiosurgery. We obtained 100% exclusion of the fistula(e) in six children, 95-80% in five, 80-50% in one and <50% in one. Of the incompletely treated cases, three had conservative management, and two with 80% and one with 60% reduction of their lesion are scheduled for elective treatment; two partially treated case died. There was no morbidity due to the endovascular procedures. Follow-up since referral is 6 months-10 years (mean 4.5 years). Ten children are neurologically normal, two have persistent (pre-existing) neurological deficits and two are dead.

Arteriovenous Fistula↗
PubMed2004

Characterization of CO3Ap-collagen sponges using X-ray high-resolution microtomography.

For reconstruction and regeneration of hard tissues, scaffold biomaterials with large size pores and high porosity are important, in addition to their roles as supporting frames. To develop a new biodegradable scaffold biomaterial, CO3Ap, which has crystallinity and a chemical composition similar to bone, was synthesized at pH 7.4 and 60 degrees C. Then, the CO3Ap was mixed with a neutralized collagen gel and the CO3Ap-collagen mixtures with different kinds of CO3Ap contents and porosity were lyophilized into sponges. Scanning electron micrography (SEM) observation of CO3Ap-collagen sponges showed favorable pores for cell invasion. Approximately 50-300 microm size pores appeared to continue through the bulk. Higher magnification of the sponge showed a better adhesion between CO3Ap crystals and collagen. X-ray high-resolution microtomography revealed a clear image of the 3D structure of the sponges. The porosity of 0, 70 and 90%(w/w) CO3Ap-collagen sponges was 79.2 +/- 2.8%, 72.6 +/- 2.4% and 48.9 +/- 6.1%, respectively. The 70%(w/w) CO3Ap-collagen sponge appeared to be the most favorable biomaterial from the viewpoint of natural bone properties. Mouse osteoblast MC3T3-E1 cells were cultured in alphaMEM with 10% FCS for 2 weeks. Hematoxylin-eosin staining confirmed osteoblast cells invaded well into the CO3Ap-collagen sponge. These sponges are expected to be used as hard tissue scaffold biomaterials for therapeutic uses.

3T3 Cells↗
PubMed2004

Selective isolation of bioactive soil actinomycetes belonging to the Streptomyces violaceusniger phenotypic cluster.

AIMS: To devise and evaluate a strategy for isolating members of the Streptomyces violaceusniger phenotypic cluster, which are known to be a promising source of bioactive metabolites. METHODS AND RESULTS: The treatment of four soil samples with 1.5% phenol (30 degrees C, 30 min) prior to inoculation on humic acid-vitamin (HV) agar eliminated most of the streptomycetes and other bacterial populations. The surviving streptomycetes on the HV isolation plates were subcultured, and species-group identification was made according to the probabilistic identification system of Williams et al. (1989). Of the 133 streptomycetes subcultured, 102 (77%), were assigned to the S. violaceusniger cluster. A test with an overlay technique revealed that all of these S. violaceusniger-cluster isolates had broad antimicrobial spectra, as they inhibited the growth of all test Gram-positive bacteria, yeasts and filamentous fungi. Antitumour activity against colon carcinoma cells was found among 68 or 67%, of these S. violaceusniger-cluster isolates, following growth in submerged culture. CONCLUSIONS: Chemical pretreatment of soil samples with phenol reduces the growth of ubiquitous Streptomyces species, thereby facilitating the recovery of less-abundant S. violaceusniger-cluster strains that are characterized by high antimicrobial and antitumour activities. SIGNIFICANCE AND IMPACT OF THE STUDY: The development and application of new methodologies with which to selectively isolate rare, bioactive streptomycete groups is important for discovering novel secondary metabolites with bioactive properties.

Anti-Infective Agents↗
PubMed2004

Retinoic acid disintegrated desmosomes and hemidesmosomes in stratified oral keratinocytes.

BACKGROUND: Although it is known that retinoic acid (RA) regulates the cellular differentiation of skin keratinocytes, the effects of RA on the anchoring junction have not been clarified. The effects of all-trans RA on cell-cell and cell-matrix connections of gingival epithelial (GE)1 cells in a multilayered culture were investigated. METHODS: Ultrastructures of GE1 cells were observed and immunohistochemistry was used to detect keratin 4, keratin 13, and desmoglein expression. Reverse transcription-polymerase chain reaction was performed to detect expression of desmosome and hemidesmosome-associating adhesion molecules, keratin 13, and keratin14. RESULTS: Retinoic acid caused immunohistochemical diminution of keratin 4, keratin 13, and desmoglein. Ultrastructurally, RA induced drastic loss of typical desmosomes and complete loss of hemidesmosomes. RA significantly decreased the transcript levels of keratin 13, keratin 14, desmoglein 1, and desmocollin 1 in a dose-dependent manner. The 230-kD bullous pemphigoid antigen (BPAG1) gene expression was also reduced by RA, whereas transcript levels of integrin alpha6, integrin beta4, the 180-kD bullous pemphigoid antigen (BPAG2), and laminin 5 were not affected. CONCLUSION: These results indicated that RA disintegrated not only desmosomes by depriving the cells of desmoglein 1, desmocollin 1, keratin 13, and keratin 4, but also hemidesmosomes by reducing the expression of BPAG1 and keratin 14 in basal keratinocytes.

Animals↗
PubMed2004

MRI characteristics of sporadic CJD with valine homozygosity at codon 129 of the prion protein gene and PrPSc type 2 in Japan.

Two Japanese sporadic Creutzfeld-Jakob disease (sCJD) patients with valine homozygosity at codon 129 of the prion protein gene and protease-resistant prion protein (PrP(Sc)) type 2 (VV2) are described. In contrast with Western countries, this type of sCJD is very rare in Japan. In 123 sCJD cases, only two were recognised as VV2 by the Japanese CJD surveillance committee. The clinical symptoms and pathological findings of the patients were similar to those of European and US patients. The noteworthy finding of diffusion weighted MRI (DWI) was that an abnormal high intensity covered a wide range of the thalamus including the dorsomedial nucleus, the pulvinar, and the ventral anterior, lateral, and posterolateral nuclei. This thalamic pattern has not been recognised in sCJD with methionine homozygosity and PrP(Sc) type 1 (MM1) or methionine/valine heterozygosity and PrP(Sc) type 1 (MV1) which comprises the vast majority of sCJD. This finding may be characteristic to VV2 and may distinguish it from MM1, MV1, and variant CJD. DWI can provide a very important clue for the antemortem diagnosis of VV2 subjects.

Aged↗
PubMed2004

Treatment with buserelin, an agonist of gonadotropin-releasing hormone, suppresses ovarian hyperstimulation syndrome induced in rabbits.

Human menopausal gonadotropin (hMG, 75 IU/body/day) and a gonadotropin-releasing hormone (GnRH) agonist buserelin (1, 10, 100 microg/kg/day) were simultaneously administered to female rabbits by the subcutaneous route for 7 days, and the effects on organ weights, plasma hormones and weight of ascitic fluid were examined. Treatment with hMG increased the ovarian weight, plasma estradiol and weight of ascites, thus indicating that ovarian hyperstimulation syndrome had been induced. Simultaneous treatment with buserelin decreased the changes induced by hMG. GnRH agonists can thus be surmised to reduce the severity of ovarian hyperstimulation syndrome in the rabbit. However, caution is needed when extrapolating the results of this rabbit model to humans.

Animals↗