Biomedical subjects

A Nakayama

Publications and source records attributed to A Nakayama.

At least 19 recordsLinked to original sources

PubMed2005

Signal transduction and cellular functions of the TEL/ARG oncoprotein.

The TEL/ARG oncogene is formed by t(1;12)(q25;p13) reciprocal translocation and is associated with human leukemia. We have previously demonstrated that the expression of TEL/ARG in Ba/F3 cells results in prolonged viability and hyper-responsiveness to IL-3. To determine the molecular mechanisms, a series of mutants of TEL/ARG were generated, and each cDNA was expressed in Ba/F3 or CHO cells. The PNT domain in TEL and K317 in ARG were essential for both signaling and biological effects. The SH3 domain in ARG was required for hyper-responsiveness to IL-3, but not for prolonged viability. The opposite was true for the SH2 domain in ARG. Mutation of Y314 in TEL, a putative GRB2-binding site, led to reduced viability, and loss of hyper-responsiveness to IL-3. All biological functions were profoundly impaired with deletion of the C-terminus in ARG, despite maintaining high levels of its kinase activity. When expressed in CHO cells, wild-type TEL/ARG induced the formation of fillopodia, in a fashion dependent on the C-terminal portion and intact kinase activity. Thus, these results suggest several critical domains within TEL/ARG necessary for function, and indicate that the signaling pathways necessary for viability, growth factor hyper-responsiveness and cytoskeletal reorganization are likely to be separate.

Actin Cytoskeleton↗

PubMed2005

Behaviour of bone marrow osteoblast-like cells on mineral trioxide aggregate: morphology and expression of type I collagen and bone-related protein mRNAs.

AIM: To investigate the in vitro behaviour of rat bone marrow cells (RBM) on mineral trioxide aggregate (MTA) (ProRoot, MTA Root Canal Repair Material; Dentsply Tulsa, Tulsa, OK, USA) compared with intermediate restorative materials (IRM) (Dentsply Caulk, Milford, DE, USA). METHODOLOGY: RBM were obtained from rat femur and were primary cultured and then subcultured. Cells were then seeded on three dishes of each material, and cultured for 3 days, after which they were evaluated morphologically using scanning (SEM) and transmission (TEM) electron microscopy. Furthermore, the calcium released from hydrated material, the cell proliferation ratio and alkaline phosphatase (ALP) activity were analysed, and the expression of type I collagen and bone-related protein mRNAs were evaluated. The data were averaged and analysed via one-way analysis of variance (anova) and were then compared by the Scheffe's test. RESULTS: SEM showed that RBM attached to MTA and had a flattened appearance without nuclear protrusions and microspikes. TEM showed that the cells attached in the same manner as the control group, but gaps larger than 2 microm were frequently seen. The calcium released from hydrated MTA was about 130 ppm after 3 days of immersion in saline. The ALP activity was similar to the control group. Cell proliferation and expression of type I collagen mRNA was significantly lower, while the expression of osteopontin mRNA was significantly higher than the control group at the third day of culture. In IRM groups, a few rounded cells were observed on the material but no living cells were seen. CONCLUSIONS: MTA is a material of low toxicity which does not inhibit cell growth, but does suppress the differentiation of osteoblast-like cells.

Alkaline Phosphatase↗

PubMed2004

Quantum dynamics in simple fluids.

We use quantum-correction factors to calculate approximately the quantum velocity time-correlation function (TCF) of supercritical Lennard-Jones argon from the classical TCF. We find that for this quite classical system, several different quantum-correction schemes yield essentially identical results for the real and imaginary parts of the quantum TCF, and also agree well with the recent forward-backward semiclassical dynamics (FBSD) results of Wright and Makri [J. Chem. Phys. 119, 1634 (2003)]. We also consider a more quantum-mechanical fluid of lighter atoms (neon) at a lower temperature. In this case different quantum-correction schemes give different results. FBSD calculations show that the harmonic quantum correction factor works the best for this system

Journal Article↗

PubMed2002

Further characterization of genes expressed during Ciona intestinalis metamorphosis.

Metamorphosis of ascidians is a dynamic event by which a nonfeeding, mobile tadpole larva is transformed into a filter-feeding, fixed juvenile. This process usually begins with the settlement of the larva and is followed by a series of coordinated morphogenetic movements that rearrange organs, tissues, and cells. To identify genes that are involved in the initiation of metamorphosis, we conducted differential screening between mRNAs of swimming larvae and those of juveniles in Ciona intestinalis. This screening permitted the isolation of cDNA clones for genes whose expression is upregulated during metamorphosis, and the characterization of four such genes (Ci-meta3, Ci-meta4, Ci-meta5 and Ci-meta6) is reported here. Ci-meta3 encodes a protein with a domain found in Sp1a and the RYanodine receptor. This gene is not expressed in early swimming larvae but is expressed in the endoderm region and part of the retractile tail region in metamorphosing juveniles. The predicted proteins encoded by Ci-meta4, Ci-meta5 and Ci-meta6 do not contain any known consensus motifs, nor do they show any similarity to known proteins. Ci-meta4 and Ci-meta5 are expressed weakly in mesenchyme cells of the early larva and strongly in the metamorphosing juvenile, while Ci-meta6 is expressed in the mesenchyme in the late larva. In addition, we characterized 53 independent cDNA clones whose expression was downregulated during the period from early swimming larvae to metamorphosing juveniles by taking advantage of the Ciona intestinalis cDNA project database and BLAST searches. The expression patterns of some of these clones were changed during the larval period.

Amino Acid Sequence↗

PubMed2001

Oxidation of activated carbon and methane using a high-frequency pulsed plasma.

We have demonstrated a new method using a high-frequency pulsed plasma for oxidizing methane and activated carbon powder (1-150 microm) as two substitutes for diesel particulate matter (PM). Methane and activated carbon can be oxidized at a rate of 4-40 and 4-10g-CH(4)/kWh, respectively. A discussion on future development of this technology is given.

Air Pollution↗

PubMed2001

Identification of the catalytic residues of bifunctional glycogen debranching enzyme.

Eukaryotic glycogen debranching enzyme (GDE) possesses two different catalytic activities (oligo-1,4-->1,4-glucantransferase/amylo-1,6-glucosidase) on a single polypeptide chain. To elucidate the structure-function relationship of GDE, the catalytic residues of yeast GDE were determined by site-directed mutagenesis. Asp-535, Glu-564, and Asp-670 on the N-terminal half and Asp-1086 and Asp-1147 on the C-terminal half were chosen by the multiple sequence alignment or the comparison of hydrophobic cluster architectures among related enzymes. The five mutant enzymes, D535N, E564Q, D670N, D1086N, and D1147N were constructed. The mutant enzymes showed the same purification profiles as that of wild-type enzyme on beta-CD-Sepharose-6B affinity chromatography. All the mutant enzymes possessed either transferase activity or glucosidase activity. Three mutants, D535N, E564Q, and D670N, lost transferase activity but retained glucosidase activity. In contrast, D1086N and D1147N lost glucosidase activity but retained transferase activity. Furthermore, the kinetic parameters of each mutant enzyme exhibiting either the glucosidase activity or transferase activity did not vary markedly from the activities exhibited by the wild-type enzyme. These results strongly indicate that the two activities of GDE, transferase and glucosidase, are independent and located at different sites on the polypeptide chain.

Amino Acid Sequence↗

PubMed2001

Characterization of two promoters that regulate alternative transcripts in the microtubule-associated protein (MAP) 1A gene.

We cloned and characterized the mouse gene for microtubule-associated protein (MAP) 1A, an important protein for neuronal morphology and mitotic spindle formation. We also investigated the 5' untranslated region of the gene to characterize the promoter units. Two alternative transcripts different in the 5' region were identified by 5' RACE. Both transcripts were principally observed in the brain. Genomic cloning revealed that exons 1, 2, and 4 generate the 5' part of a long transcript, whereas exons 3 and 4 generate a short transcript. Putative 5' and intronic promoters flanking exons 1 and 3, respectively, are GC-rich and lack a canonical TATA box. DNase I footprinting from mouse cells revealed that several potential cis-elements were occupied by nuclear proteins. A reporter assay system in conjunction with a number of deletion and mutation constructs was used to test the two putative promoters. Both putative promoters showed transactivity and their function was dependent upon Sp1 sites. In addition, an NF-1 site, an HNF3B site, and an AP-1/ATF site were necessary for basal promoter activity of the intronic promoter. Our data provide insight into the regulatory mechanisms that govern the expression of the MAP1A gene.

3T3 Cells↗

PubMed2001

Isolation and characterization of genes that are expressed during Ciona intestinalis metamorphosis.

In ascidians, the events of metamorphosis transform the non-feeding, mobile tadpole larva into a filter-feeding, fixed juvenile, and the process involves rearrangements of cells, two organs and physiological changes. Differential screening was used to isolate two genes that are not expressed in swimming larvae but are expressed immediately after the initiation of metamorphosis in Ciona intestinalis. One of the genes, Ci-meta1, encodes a polypeptide with a putative secretion signal sequence, 6 epidermal growth factor (EGF)-like repeats and 13 calcium-binding EGF-like repeats. The gene begins to be expressed immediately after the beginning of metamorphosis in the adhesive organ and is likely to be associated with the signal response for metamorphosis. Another gene named Ci-meta2 encodes a protein with a putative secretion signal and three thrombospondin type-1 repeats. Ci-meta2 gene expression begins at the larval stage and is upregulated in the metamorphosing juveniles. Ci-meta2 expression is found in three regions; the adhesive organ which is also associated with settlement, the neck region between the trunk and the tail of the larva which is associated with tail resorption, and dorsal regions of the trunk which correspond to the location of the siphon primordium. This gene may be involved in the dynamic arrangement of cells during ascidian metamorphosis.

Amino Acid Sequence↗

PubMed2001

Ileal adenomyoma accompanied by primary peritonitis: report of a case.

We report herein the case of a 52-year-old woman who presented with severe abdominal pain and a 2-week history of a yellow vaginal discharge. An emergency operation was performed for localized peritonitis attributed to acute perforated appendicitis. There were no findings to indicate the cause of peritonitis, but by chance, a submucosal tumor was found in the ileum 2m from Bauhin's valve. Appendectomy and wedge resection of the ileum with the submucosal tumor were carried out. The peritonitis was considered to have been idiopathic from bacterial and molecular biological examination of the ascites. Pathological, immunohistochemical, and flow cytometrical findings of the resected ileal submocosal tumor indicated a diagnosis of ileal adenomyoma with no malignancy, which suggested metaplasia of the pancreaticobiliary to gastric epithelium.

Adenomyoma↗

PubMed2001

Kit(+) melanocytes seem to contribute to melanocyte proliferation after UV exposure as precursor cells.

Melanogenesis caused by UV exposure is characterized by proliferation and differentiation of functioning melanocytes in epidermis. Recently, the existence of precursor melanocytes in normal skin was proposed immunohistochemically. Thus, this precursor melanocyte seems to proliferate and differentiate into mature pigmented melanocytes after UV exposure. To elucidate how these processes occur, we examined C57BL mouse epidermal sheets after UV exposure immunohistochemically. In normal epidermis, TRP-1(+) cells and Kit(+) cells were easily identified and the cellularities were 41.0 and 31.7 cells per mm(2), respectively. Only a few Mitf(+) cells and no TRP-2(+) cells were observed. On the first day after UV exposure, Mitf(+) cells and TRP-2(+) cells appeared, whereas the numbers of TRP-1(+) cells and Kit(+) cells decreased. Some Kit+ cells also expressed Mitf, but no TRP-1 and Mitf double positive cells were seen. In this period, some Mitf(+) cells were labeled with BrdU. The next day, Mitf(+) cells and TRP-2(+) cells increased to the maximum cellularity, and they decreased thereafter and disappeared on the seventh day. An increase of TRP-1(+) cells was first identified on the fifth day after UV exposure, and reached a cellularity four times as great as that of the normal control on the fourteenth day. The subepidermal injection of Kit antibody attenuated the increase of Mitf+ cells and TRP-1(+) cells. These findings suggested that precursor cells that reside in the skin, first differentiated into Mitf(+) and TRP-2(+) melanocytes by the activation of the Kit receptor, then become mature TRP-1(+) melanocytes after UV exposure.

Animals↗

PubMed2001

Transcriptional regulation of interferon gamma gene by p300 co-activator.

Interferon gamma (IFN gamma) is an important immunoreguratory protein and is secreted from CD4+, CD8+ T cells and NK cells. Expression of IFN gamma gene is regulated by either DNA-methylation or cis-elements of transcriptional factors such as AP-1, NFAT, AP-4, YY-1, ATF and GATA. At a putative ATF binding site in a promoter region of IFN gamma gene, the position from -59 to -43, is important for the IFN gamma promoter activity. Our gel-shift competition studies demonstrated that addition of antibodies against ATF-2 caused super-shifts of DNA-protein complexes. In addition, it was clarified that p300 was involved in DNA-protein complexes by in vitro "pull-down" experiments. Moreover, a co-expression of p300 and ATF-2 enhanced the promoter activity of IFN gamma gene. Thus, these results indicate that p300 and ATF-2 play critical rules in a basal transcription of IFN gamma gene in Jurkat T cells.

Activating Transcription Factor 2↗

PubMed2001

Value of lipiodol computed tomography and digital subtraction angiography in the era of helical biphasic computed tomography as preoperative assessment of hepatocellular carcinoma.

OBJECTIVE: To compare the diagnostic accuracies of Lipiodol computed tomography (CT) and helical biphasic CT as preoperative imaging modalities for hepatocellular carcinoma (HCC). SUMMARY BACKGROUND DATA: Lipiodol CT after digital subtraction angiography has long been used as a highly sensitive imaging modality for HCC. The recent advent of helical CT has allowed scanning the entire liver during both the arterial and portal venous phase of contrast enhancement. METHODS: The authors analyzed data from 164 patients who underwent hepatic resection for HCC to calculate the sensitivity and specificity of these modalities. Findings of intraoperative ultrasonography followed by histologic confirmation were set as the gold standard. RESULTS: Although sensitivity decreased with both modalities as tumors became small and well differentiated, helical CT showed a higher sensitivity than Lipiodol CT in detecting well-differentiated HCC nodules smaller than 2 cm. In contrast, Lipiodol CT was superior to helical CT for the detection of small but moderately to poorly differentiated nodules. The overall sensitivity of helical CT was higher than that of Lipiodol CT. These findings suggest that helical CT is superior in delineating early HCC, whereas Lipiodol CT is specific to the detection of intrahepatic metastases. In terms of specificity, helical CT was superior to Lipiodol CT. CONCLUSIONS: Helical CT and Lipiodol CT are complementary modalities. At present, helical biphasic CT does not obviate the need for invasive techniques such as angiography and Lipiodol CT as preoperative examinations for HCC.

Adult↗

PubMed2001

A study of factors influencing prognosis after resection of hepatic metastases from colorectal and gastric carcinoma.

OBJECTIVE: The aim of this study is to determine the absolute contraindication for hepatic resection for colorectal metastases and investigate the value of hepatectomy for gastric metastases by comparing it with the results of colorectal metastases performed with the same criteria. METHODS: A retrospective cohort study was conducted in patients undergoing hepatic resection for metastatic colorectal (n = 64) and gastric (n = 17) carcinomas. Common predictive factors for both metastases were analyzed by the stratified Cox proportional hazard model. In this model, the different baseline hazard was set for each disease, whereas the risk of each covariate was assumed to be equal in both gastric and colorectal metastases. RESULTS: Overall 1-, 2-, and 5-yr survival rates after hepatectomy for colorectal and gastric metastases were 90%, 73%, 42%, and 47%, 22%, 0%, respectively. Factors controlling prognosis were as follows: age > or = 60, extrahepatic metastases, serosal invasion, grade of lymph node metastases, tumor cell differentiation of the primary lesion(s), carcinoembryonic antigen level, tumor-exposed surgical margin, and blood transfusion. In particular, presence of extrahepatic metastases showed the markedly high-risk ratio among these eight variables. CONCLUSIONS: Hepatectomy, if possible, is indicated in patients with hepatic metastases from colorectal carcinoma if there are no extrahepatic metastases and if the primary disease is controlled. It is indicated only in carefully selected patients with metastases from gastric carcinoma.

Adult↗

PubMed2001

Gene expression profiles in Ciona intestinalis tailbud embryos.

A set of 3423 expressed sequence tags derived from the Ciona intestinalis tailbud embryos was categorized into 1213 independent clusters. When compared with DNA Data Bank of Japan database, 502 clusters of them showed significant matches to reported proteins with distinct function, whereas 184 lacked sufficient information to be categorized (including reported proteins with undefined function) and 527 had no significant similarities to known proteins. Sequence similarity analyses of the 502 clusters in relation to the biosynthetic function, as well as the structure of the message population at this stage, demonstrated that 390 of them were associated with functions that many kinds of cells use, 85 with cell-cell communication and 27 with transcription factors and other gene regulatory proteins. All of the 1213 clusters were subjected to whole-mount in situ hybridization to analyze the gene expression profiles at this stage. A total of 387 clusters showed expression specific to a certain tissue or organ; 149 showed epidermis-specific expression; 34 were specific to the nervous system; 29 to endoderm; 112 to mesenchyme; 32 to notochord; and 31 to muscle. Many genes were also specifically expressed in multiple tissues. The study also highlighted characteristic gene expression profiles dependent on the tissues. In addition, several genes showed intriguing expression patterns that have not been reported previously; for example, four genes were expressed specifically in the nerve cord cells and one gene was expressed only in the posterior part of muscle cells. This study provides molecular markers for each of the tissues and/or organs that constitutes the Ciona tailbud embryo. The sequence information will also be used for further genome scientific approach to explore molecular mechanisms involved in the formation of one of the most primitive chordate body plans.

Animals↗

PubMed2001

Phenotypes associated with replacement of His by Arg in the Pendred syndrome gene.

BACKGROUND: Pendred syndrome is often associated with inner ear malformations, especially enlarged vestibular aqueduct (EVA). Recently, mutations in the Pendred syndrome gene (PDS) have been reported in patients with EVA, in addition to those with classical Pendred syndrome. OBJECTIVE: The aim of this study was to investigate the genotype-phenotype correlations of PDS. METHODS: Each of the 21 exons and flanking splice regions of PDS was analysed by direct DNA sequencing in nine patients with EVA; allele-specific amplification was performed to confirm the mutation. Genetic analyses were compared with thyroid function tests, perchlorate discharge tests, thyroid volume and pure-tone audiogram. Magnetic resonance imaging was used to determine the volume of the endolymphatic duct and sac of each patient. RESULTS: A missense mutation, H723R, was identified in the homozygous state in three patients and in the heterozygous state in another three. Although none of the patients had goitre, increased serum thyroglobulin and an abnormal degree of iodide release were correlated with the number of mutant alleles identified. However, there was no relationship between the degree of hearing loss and the number of mutant alleles. CONCLUSION: The present study reveals that the number of mutant alleles correlates with the degree of subclinical thyroid abnormality, but not with the degree of hearing loss in Japanese patients with the PDS missense mutation H723R.

Adolescent↗

PubMed2001

Induction of the expression of SCF in mouse by lethal irradiation.

To clarify what kinds of cytokines are actually contributing to proliferation of hemopoietic stem cells in vivo after lethal irradiation, we have investigated the expression of some cytokines by RT-PCR method. Above all, expression of the SCF was increased significantly in the bone marrow cells soon after lethal irradiation in both the Sca-1 (+) bone marrow cells injected and non-injected mice. The day 6 serum from the lethally irradiated mice could support the proliferation of the Sca-1 (+) bone marrow cells, even though the serum from normal mice could not. The quantification analyses have revealed the increase of the amounts of IL-6 and flt3-ligand in their serum, but not significant increase of the amount of SCF. Precise PCR analysis has revealed that the cell surface associated form of SCF was significantly induced in the bone marrow after lethal irradiation. These data indicate that the cell surface form of SCF mainly promotes the proliferation of hemopoietic stem cells with some soluble cytokines under sever lack of hemopoietic stem cells in vivo caused by lethal irradiation and also suggest the importance of direct cell-to-cell interaction on proliferation of hematopoietic stem cells in vivo.

Animals↗

PubMed2001

Hyperbaric oxygen therapy for the treatment of large vestibular aqueduct syndrome.

Eight patients with large vestibular aqueduct (LVA) syndrome and acute sensorineural hearing loss that had not responded to intravenous treatment were treated with hyperbaric oxygen(HBO2) therapy. This was performed daily, with 15 treatments per course. Pure tone and speech audiometry were performed on all patients. The mean hearing recovery following HBO2 therapy (20.8 +/- 12.1 dB) was significantly higher than after intravenous treatment (2.3 +/- 7.2 dB) (P < 0.01), although treatment duration was not different between the two therapies. Of the eight patients, five showed complete or partial recovery after one course of HBO2 therapy, and their hearing levels have not since changed. The other three patients showed heating recovery during therapy, but treatment had to be repeated for two or more courses because of progressive or fluctuating hearing loss.We consider HBO2 therapy should be used to treat acute hearing deterioration associated with LVA syndrome if patients do not recover their hearing ability following conventional treatment

Adult↗

PubMed2000

Comparison of the mutations induced by p-benzoquinone, a benzene metabolite, in human and mouse cells.

Benzene is one of the chemicals widely contaminating the environment. Benzene is suggested to be a human leukemogen. When benzene is absorbed in the human body, it is metabolized firstly in the liver and subsequently in the bone marrow where it provokes initiation of leukemia. In the present study, we analyzed mutations induced by p-benzoquinone (p-BQ), a benzene metabolite, in human cells using a shuttle vector plasmid pMY189, and compared frequencies, types and spectra of the mutations with those of the mutations previously revealed in mouse cells using a similar plasmid pNY200. We found that p-BQ induces mutations in human and mouse cells at similar frequencies but with different types of mutagenesis. The proportion of tandem base mutations was significantly lower in human cells than in mouse cells. Most base substitutions were induced in G:C base pairs in both human and mouse cells. However, the proportion of G:C-->C :G transversion is significantly higher in human cells. These findings indicate that the p-BQ-induced DNA damage in human and mouse cells is processed in a different manner, and that extrapolation of mice findings on experimental benzene carcinogenesis to human cancer risk assessment should be conducted carefully.

Animals↗