Biomedical subjects

T Yamashiro

Publications and source records attributed to T Yamashiro.

At least 19 recordsLinked to original sources

PubMed2006

Site-specific mutation of the interferon sensitivity-determining region (ISDR) modulates hepatitis C virus replication.

The number of amino acid substitutions in the interferon sensitivity-determining region (ISDR) in the nonstructural 5A (NS5A) gene of hepatitis C virus (HCV) is closely associated with the interferon (IFN) response and viral load. Several HCV replicon-based studies have reported that ISDR sequences had an influence on viral replication in vitro. However, it is unclear as to how different ISDR sequences affect HCV replication. Various clinically observed ISDR sequences were introduced into HCV replicons and their contribution to viral replication was investigated using a colony formation assay and/or a transient replication assay. A mapping study of the ISDR was performed to identify the amino acid positions that critically affect replication. While no colonies were formed in the colony formation assay using HCV replicons with few mutations (0, 1 and 3) in the ISDR, numerous colonies (>200) appeared when using constructs with six mutations. Introduction of various distinct ISDR sequences with multiple mutations resulted in replication enhancement in transient assays. A mapping study identified several specific sites in the ISDR that critically affected replication, including codon 2209 which, in patients, was closely associated with a strong response to IFN. ISDR sequences associated with a clinical IFN response and viral load modulated the replication of HCV replicons, suggesting the importance of the ISDR sequence in HCV infection.

Amino Acid Sequence↗

PubMed2005

Dielectric behavior of pulmonary edema induced in the rat lung.

The dielectric properties (conductivity, kappa and relative permittivity, epsilon) of excised rat lung are modified by lung air and water content. The measurements of these quantities were made over the frequency range of 10 kHz to 100 MHz with an open-ended coaxial probe. The following relationships were analyzed in an oleic acid-induced pulmonary edema model using 18 animals: the spectra of kappa, epsilon and the loss tangent as a function of lung air and water content. Secondly, an isolated-perfused lung system was produced to induce a gradual increase in lung water. The time course of kappa, epsilon and the loss tangent for one excised lung was analyzed. The principal findings were: (i) a decrease in kappa and epsilon with increasing air content, (ii) an increase in kappa and epsilon with increasing water content, and (iii) a good correlation between lung water content and maximum loss tangent that was insensitive to changes in air content. We conclude that this technique could provide a quantitative assessment of lung water during pulmonary edema formation.

Analysis of Variance↗

PubMed2005

Effects of positive pressure in odontogenic keratocysts.

Intracystic fluid pressure is thought to be involved in odontogenic cyst growth. In this study, we investigated the effects of positive pressure on the expression of interleukin-1alpha (IL-1alpha), matrix metalloproteinases (MMPs), and prostaglandin E2 (PGE2) in odontogenic keratocysts to determine whether this pressure stimulates inflammatory cytokine production and signaling of osteoclastogenic events. Positive pressure enhanced the expression of IL-1alpha mRNA and protein in odontogenic keratocyst epithelial cells, and increased the secretion of MMP-1, MMP-2, MMP-3, and PGE2 in a co-culture of odontogenic keratocyst fibroblasts and the epithelial cells. The pressure-induced secretions were inhibited by an interleukin-1 receptor antagonist. Recombinant human interleukin-1alpha (rhIL-1alpha) increased the secretion of MMP-1, MMP-2, MMP-3, and PGE2 in the fibroblasts. Furthermore, in the fibroblasts, rhIL-1alpha enhanced the expression of macrophage colony-stimulating factor (M-CSF) mRNA, and rhIL-1alpha-induced PGE2 increased the expression of nuclear factor kappaB ligand (RANKL) mRNA. Thus, positive pressure may play a crucial role in odontogenic keratocyst growth via stimulating the expression of IL-1alpha in epithelial cells.

Carrier Proteins↗

PubMed2004

Relation between size of odontogenic jaw cysts and the pressure of fluid within.

Intracystic fluid pressure may have a crucial role in the growth of odontogenic jaw cysts. In this study, we investigated the relation between the size of the cyst and the pressure of the fluid within odontogenic keratocysts, dentigerous cysts, and radicular cysts. The radiolucent area of the cyst on a panoramic radiograph was linearly related to the volume in the cavity, and the correlation coefficient (gamma) was 0.70 (n = 25, P < 0.001). Intracystic fluid pressure correlated negatively with the radiolucent area in odontogenic keratocysts (gamma = -0.76, n = 9, P = 0.02), dentigerous cysts (gamma = -0.54, n = 16, P = 0.03), and radicular cysts (gamma = -0.69, n = 10, P = 0.03). The values of [(intracystic fluid pressure (mmHg)) x (radiolucent area (cm(2)))] did not differ significantly among the three types of cyst. Intracystic fluid pressure may therefore be negatively related to the size of all three types of cyst.

Adolescent↗

PubMed2004

Alanine aminotransferase elevation not associated with fatty liver is frequently seen in obese Japanese women.

OBJECTIVE: To determine the prevalence of fatty liver and alanine aminotransferase (ALT) elevation in obese Japanese women and to clarify the factors contributing to fatty change and ALT elevation in the cohort. DESIGN: Cross-sectional and population-based study. SUBJECTS: From 4366 women who received their annual health check-up, 4211 women were selected for analysis. All 4211 women were negative for hepatitis virus markers. MEASUREMENTS: Peripheral blood cell counts, liver biochemical tests, fasting glucose, cholesterol and triglyceride levels, uric acids, glycosylate hemoglobin A1c, and ultrasound examination. RESULTS: Ultrasonographic evidence of fatty liver and ALT elevation was seen in 391 (9.3%) and 238 (5.7%), respectively, of the 4211 women. Frequencies of both fatty liver and ALT elevation increased with increase in the degree of obesity. The frequency of ALT elevation was higher in women with fatty liver than in women without fatty liver among the nonobese or mildly obese group. However, the frequency of ALT elevation was not significantly different between women with fatty liver and women without fatty liver among the severely obese group. Multivariate analysis showed that obesity, hemoglobin (> or = 14 g/dl), triglyceride (> or = 150 mg/dl), diabetes mellitus, and fatty liver were significant predictors of ALT elevation. However, only two variables, hemoglobin (> or = 14 g/dl) and presence of diabetes, were significant in the severely obese group. CONCLUSIONS: ALT elevation not associated with fatty liver was frequently seen in obese women, suggesting that obesity is directly associated with the elevated ALT level in Japanese obese women. In addition, hemoglobin (> or = 14 g/dl) was a strong predictor of ALT elevation in the severely obese group.

Adult↗

PubMed2004

Introduction of NS5A mutations enables subgenomic HCV replicon derived from chimpanzee-infectious HC-J4 isolate to replicate efficiently in Huh-7 cells.

Hepatitis C virus (HCV) subgenomic replicon has been reported to replicate efficiently and continuously in human hepatoma Huh-7 cells. To extend the previous results to other isolated HCV clones, we constructed another HCV replicon from HC-J4, one of chimpanzee-infectious HCV clones. An HCV replicon derived from HC-J4 (RpJ4) consists of HCV-5' untranslated region, neomycin phosphotransferase gene, the encephalomyocarditis virus internal ribosomal entry site, HCV nonstructural region, NS3 to NS5B, and HCV-3' untranslated region. The adaptive mutations known to be required for HCV-Con1 replicon were introduced in RpJ4 replicon, aa.(amino acids number according to HC-J4) 2197 serine to proline, deletion of serine at aa.2201, and aa.2204 serine to isoleucine (RpJ4-S2197P, RpJ4-S22001del, and RpJ4-S2204I). RpJ4/ISDR mutant and RpJ4-S2201del/ISDR mutant were also constructed by introducing six amino acid mutations into the interferon sensitivity determining region (ISDR). After transfection into Huh-7 cells and G418 selection, RpJ4 and RpJ4/ISDR mutants did not produce any colony. In contrast, G418-resistant cells were transduced efficiently by RpJ4-S2197P, RpJ4-S2204I, RpJ4-S2201del and RpJ4-S2201del/ISDR mutant, with the RpJ4-S2201del/ISDR mutant being most efficient. Hence the HCV replicon derived from HC-J4 can replicate efficiently following the introduction of adaptive mutations into the upstream region of ISDR. Moreover, additional introduction of mutations into ISDR further enhanced its replication. These findings demonstrate that the genetic structure of the NS5A domain is critical in HCV replications.

Amino Acid Sequence↗

PubMed2004

Denervation resulting in dento-alveolar ankylosis associated with decreased Malassez epithelium.

Inferior alveolar nerve denervation causes appreciable decreases in the distribution of epithelial rests of Malassez. To explore roles of the Malassez epithelium, we attempted to evaluate possible changes in dento-alveolar tissues surrounding this epithelium by experimental denervation. We found that denervation led to dento-alveolar ankylosis with a decrease in the width of the periodontal spaces. Interestingly, with regeneration of the Malassez epithelium 10 weeks after the denervation, the periodontal space width showed a correspondingly significant increase. These findings suggest that the Malassez epithelium may be involved in the maintenance of periodontal space and that sensory innervation might be indirectly associated with it. In addition, it is of interest that denervation activated root resorption of the coronal root surface and that the consequently resorbed lacunae were repaired by cellular cementum. It is suggested that Malassez epithelium may negatively regulate root resorption and induce acellular cementum formation.

Acid Phosphatase↗

PubMed2003

High levels of genetic diversity in island populations of the island endemic Suzukia luchuensis (Labiatae).

Genetic diversity and genetic differentiation within and among island populations was examined by allozyme electrophoresis in Suzukia luchuensis (Labiatae), which is endemic to four of the Ryukyu Islands, southern Japan, and one island near Taiwan. Intrapopulation allozyme diversity was very low in all the four Ryukyu Islands, probably due to the effects of random drift in small populations. In contrast, genetic diversity at the species level was high, possibly because of an ancient origin of populations and/or multiple colonization of the species on different islands. Genetic differentiation among the overall populations was high (G(ST)=0.863), while gene flow (Nm) as estimated from allozyme frequency data was 0.041, suggesting that its occurrence among populations is highly restricted. Hierarchical analysis of genetic differentiation indicated that a high proportion of the total allelic variance is attributed to variation among islands, corresponding to the fact that several alleles were fixed on only one island. However, intraisland genetic differentiation was small on all islands except Yonaguni Island, where S. luchuensis is relatively widely distributed. Most diversity was thus due to differences among islands.

Gene Frequency↗

PubMed2003

Expression of bone morphogenetic proteins and Msx genes during root formation.

Like crown development, root formation is also regulated by interactions between epithelial and mesenchymml tissues. Bone morphogenetic proteins (BMPs), together with the transcription factors Msx1 and Msx2, play important roles in these interactions during early tooth morphogenesis. To investigate the involvement of this signaling pathway in root development, we analyzed the expression patterns of Bmp2, Bmp3, Bmp4, and Bmp7 as well as Msx1 and Msx2 in the roots of mouse molars. Bmp4 was expressed in the apical mesenchyme and Msx2 in the root sheath. However, Bmps were not detected in the root sheath epithelium, and Msx transcripts were absent from the underlying mesenchyme. These findings indicate that this Bmp signaling pathway, required for tooth initiation, does not regulate root development, but we suggest that root shape may be regulated by a mechanism similar to that regulating crown shape in cap-stage tooth germs. Msx2 expression continued in the epithelial cell rests of Malassez, and the nearby cementoblasts intensely expressed Bmp3, which may regulate some functions of the fragmented epithelium.

Animals↗

PubMed2002

Osteosarcoma around the knee. Intraepiphyseal excision and biological reconstruction with distraction osteogenesis.

In 11 patients juxta-articular osteosarcoma around the knee was treated by intraepiphyseal excision of the tumour and reconstruction of the bone defect by distraction osteogenesis. Preoperative and postoperative chemotherapy was given to eight patients with high-grade tumours. The articular cartilage of the epiphysis and a maximum of healthy soft tissues were preserved. Distraction osteogenesis was then carried out. The mean gain in length was 9.7 cm. Full function of the limb was preserved in all except one patient, with a mean follow-up of 53.8 months. Treatment of juxta-articular osteosarcomas around the knee with joint preservation and biological reconstruction using distraction osteogenesis can give excellent functional results.

Adolescent↗

PubMed2002

[Study of the difference between the clinical diagnostic criteria and results of immunohistochemical staining].

If more than 2 lesions of cancer are observed in the lung, differences in the histology or in situ component is the basic criterion for multicentricity. In addition, remote lung mass with same histology in the absence of both distant metastasis and mediastinal lymphadenopathy is also regarded as multicentricity. We have studied the difference between the clinical diagnostic criteria and the results of immunohistochemical staining. Thirteen patients who were diagnosed as double lung cancers under the clinical of Martini et al or Cortese et al were reviewed. Of them, clinically 6 patients had synchronous double lung cancers and 7 patients had metachronous double lung cancers. Four patients in each group with combination of adenocarcinoma (AD) and bronchiolo-alveolar cell carcinoma (BAC) were studied by immunohistochemical staining. As the result, 3 patients in the former group were defined as the synchronous double lung cancers, however in the latter group, only 1 patients was defined as the metachronous double lung cancers. As for from the histological findings, if either of multiple lung cancer lesion were Noguchi's A or B typed BAC, the patients are prone to have double lung cancers. Subsequently if the histology of the both lesions were the same as AD-AD or Noguchi's C typed BAC-BAC, then the patients are prone to have the metastatic lung cancers.

Aged↗

PubMed2002

[The usefulness of induction chemotherapy in cases with tumors showing border-line pathological aspects between thymoma and thymic carcinoma].

We present 2 surgically treated cases with thymoma classified as Masaoka stage III and IV a (type B 3 thymoma), which showed the border-line pathological aspects between the thymoma and thymic carcinoma. Induction chemotherapy [CAV-PVP (cyclophosphamide, adriamycin, vincristine sulfate, etoposide) therapy in one case and ADOC (adriamycin, cisplatin, vincristine sulfate, cyclophosphamide) therapy in another case] preluded their surgical resection resulted in reduction of the tumor's size moderately or severely. After achievement of induction chemotherapy, these tumors were resected with the midsternotomy approach, along with resection of the right upper lobe and the left brachiocephalic vein replacing the expanded pdytetrafluoroethylene (ePTFE) graft following mediastinal lymphnodes dissection in one case and leaving the tumor tissue around the pulmonary trunk in another case. Postoperative irradiation of 40 Gy in one case and 60 Gy in another case were performed in the mediastinal regions. From pathological aspects especially in second case, though the specimen by preoperative needle biopsy stained positive for bcl-2 and strong immunoreactivity (20%) for MIB-1, specimens excised operatively after induction chemotherapy showed negative staining for bcl-2 and little staining (lower than 5%) for MIB-1. This fact indicates that the induction chemotherapy makes the tumor less malignant, in other words, from the face of thymic carcinoma to the face of thymoma. Induction chemotherapy performed for the purpose of reducing the tumor size was very advantage in these 2 cases with type B 3 thymoma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2001

Alcoholic liver cirrhosis complicated with torsade de pointes during plasma exchange and hemodiafiltration.

A 36-year-old man with severe alcoholic hepatitis was treated with plasma exchange combined with hemodiafiltration to remove endotoxins and inflammatory cytokines. During the treatment, he had critical arrhythmia (torsade de pointes [TdP]). His laboratory data showed hypomagnesemia, which was suspected to be responsible for the development of TdP. Patients with alcoholic liver disease tend to have hypomagnesemia and Q-T interval prolongation. Furthermore, hemodiafiltration may cause hypomagnesemia. Careful observation for electrolytic imbalance is necessary when clinicians treat patients with alcoholic liver failure with a liver support system.

Adult↗

PubMed2001

Correlation between serum transaminase activity and virus load among patients with chronic liver disease type B.

Newly developed hepatitis B virus (HBV)-DNA quantitative assays, transcription-mediated amplification and hybridization protection assay (TMA-HPA) and branched-DNA assay were clinically evaluated. The subjects consisted of 160 chronic HBV carriers; 48 were hepatitis Be antigen (HBeAg)-positive, whereas 109 were anti-HBe-positive (three were both negative). All subjects with HBeAg, except one, showed high HBV-DNA replication levels (>/=10(5.8) copies/ml). In HBeAg negative subjects, there was a strong correlation between the serum HBV-DNA and alanine aminotransferase (ALT) levels; ALT level was usually normal if the samples tested showed an HBV-DNA level less than 10(5)/ml, whereas, the majority of the sera with an HBV-DNA concentration greater than 10(7)copies/ml showed elevation in serum ALT level. An intermediate range of HBV-DNA level (10(5)-10(7) copies/ml) was associated with variable ALT activity. In conclusion, a serum HBV-DNA level associated with ALT elevation was lower in patients with type B chronic liver disease negative for HBeAg compared with their HBeAg-positive counterparts. There was usually no or mild liver disease activity when patients with chronic HBV infection have serum HBV-DNA levels less than 10(5)copies/ml.

Journal Article↗

PubMed2001

Hepatitis B virus harboring nucleotide deletions in the core promoter region and genotype B correlate with low viral replication activity in anti-HBe positive carriers.

BACKGROUND: Emergence of anti-HBe following seroconversion of HBe antigen indicates reduced hepatitis B virus (HBV) replication in the liver and low infectivity in the natural course of infection. However, some patients show continued replication or reactivation even in the presence of anti-HBe. OBJECTIVE: To clarify the cause of HBV replication, we investigated genotype differences and mutations in the core promoter and precore region in relation to virus titer. STUDY DESIGN: Using quantification of HBV DNA, nucleotide sequencing of the core promoter and precore region, and genotyping with the S gene by restriction fragment length polymorphism (RFLP), we analyzed sera of 26 anti-HBe positive carriers (28 serum samples). RESULTS: Various mutations were detected including C to T point mutation at nt 1653, A to T and G to A contiguous point mutations at nt 1762 and 1764 in the core promoter region, and G to A point mutation at nt 1896 in the precore region, but no common mutations were detected that were directly related to the virus titer from earlier reported mutations. In contrast, the mean titer of genotype B virus was 1.5 x 10(5) copies per ml and that of mutant HBV of genotype C having 8 base pairs (8-bp) deletion (nt 1768-1775) in the core promoter region was 7.9 x 10(4) copies per ml (mean titer). These titers showed commonly lower than that of genotype C virus without 8-bp deletion (median titer 5.0 x 10(6) copies per ml). Transition of genotype from C to B after viral reactivation and reduction of proportion of 8-bp deletion mutant at reactivation period was observed in a patient who demonstrated exacerbation of liver dysfunction due to immunosuppressive therapy and increased viral replication. CONCLUSIONS: These results confirm those of our earlier study describing low replication ability of 8-bp deletion mutant HBV in vitro, and also indicate that the presence of genotype B correlates with reduced titer of HBV.

Adult↗

PubMed2001

Gene and protein expression of brain-derived neurotrophic factor and TrkB in bone and cartilage.

Gene and protein expressions of brain-derived neurotrophic factor (BDNF) and TrkB, the high-affinity receptor of BDNF, were investigated in the femur and mandibular condyle of rats by in situ hybridization and immunohistochemistry. BDNF and TrkB mRNA showed overlapped expression in chondrocytes in proliferating and mature zones of the epiphyseal growth plate cartilage and mandibular condylar cartilage, and in cuboidal-shaped active osteoblasts at the site of endochondral and intramembranous ossification and in trabecular bone. Expression of BDNF protein also showed a similar localization. The present study suggests that BDNF may participate in regulating the development and remodeling of bony tissue in the developing rat.

Animals↗

PubMed2001

An approach to enhance the interface adhesion between an orthodontic plastic bracket and adhesive.

For the purpose of improving the degree of success of plastic bracket bonding, based on the analysis of the chemical components of plastic brackets, a systematic method for the treatment of the adhesive surface of plastic brackets was introduced in this study. After sandblasting the adhesive surfaces of two commercially available plastic brackets (Spirit and Clear Bracket), a favourable surface treatment was obtained with the application of a silane coupling agent, gamma-methacryloxy propyl trimethoxy silane. The findings showed that (i) the fillers added to the plastic brackets were glass fillers with Si-OH groups distributed on their surfaces; (ii) sandblasting of the bracket surface resulted in exposure of the glass fillers; (iii) combined with sandblasting, silane coupling treatment significantly increased the bond strength (P < 0.05), which was adequate to withstand the forces generated during orthodontic therapy; and (iv) treatment with sandblasting and silane coupling 24 hours before direct bonding did not cause a significant reduction in bond strength. It is concluded that sandblasting and silane coupling treatment offers the benefit of increasing the in vitro bond strength of plastic brackets for orthodontic application.

Adhesiveness↗

PubMed2001

Gene analysis of Vibrio cholerae NAGV14 pilus and its distribution.

Adhesive pilus of Vibrio cholerae 034, strain NAGV14, was genetically analyzed. The deduced amino acid (aa) sequence of the major pilin structural gene (VcfA) was 67% homologous to the MshA pilin in the N-terminal region, but no homology was found in the C-terminal region which contained the antigenic epitopes. Upstream and downstream flanking regions examined were highly homologous to mshB and mshC of the MSHA (mannose-sensitive hemagglutinin) gene locus. A short leader sequence and a pair of cysteines near the C-terminus which are the characteristics of type 4a pilus family were found. The major pilin structural gene of NAGV14 was compared to that of a strain V10 producing non-adhesive pili. The deduced aa sequences showed 60% homology, and the distance between two cysteines in the C-terminal region was different. A total of 177 V. cholerae strains were investigated for the presence of a type 4 pilus gene locus by PCR, and 95% were positive. The major pilin gene of NAGV14 was detected in 4 of 93 V. cholerae non-O1, non-0139 strains tested, but none of the V. cholerae O1 and O139 (72 and 12 strains, respectively). Our result suggested that a type 4 pilus gene locus similar to the MSHA gene locus is widely distributed among V. cholerae strains. We proposed naming this type 4 pilus gene locus the VCF (for V. cholerae flexible pili) gene locus.

Amino Acid Sequence↗