Biomedical subjects

Y Nagata

Publications and source records attributed to Y Nagata.

At least 37 records · Page 2Linked to original sources

PubMed2002

Beneficial effects of synthetic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate), on stratum corneum function.

The effects of a newly synthesized phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) [poly(MPC-co-BMA)], on the water barrier function and water-holding capacity of the stratum corneum were examined by measuring transepidermal water loss (TEWL) and electrical conductance of the skin surface. On the backs of four NC mice, the epidermal permeability barrier was abrogated by cellophane tape stripping 30 times. The skin was then treated with 0.1% poly(MPC-co-BMA) or distilled water twice daily for the following 3 days. Poly(MPC-co-BMA) reduced TEWL significantly compared with the control after the first treatment (P = 0.044) and this effect was observed for 3 days. In human skin, water-holding capacity was measured at 5, 10, 15, 30 min and 1, 2, and 4 h after the application of poly(MPC-co-BMA) or distilled water to both volar forearms of 21 healthy volunteers. Skin treated with poly(MPC-co-BMA) showed significantly greater ability to retain water at all time points. Poly(MPC-co-BMA) is the first synthetic material that can enhance both the water barrier function and water-holding capacity of the stratum corneum. Our results indicate that this substance may be useful clinically in the treatment of dry skin.

Adult↗

PubMed2002

Clinical, histopathological and immunological distinction in two cases of IgA pemphigus.

Two cases of IgA pemphigus, one of the subcorneal pustular dermatosis (SPD) type and one of the intraepidermal neutrophilic IgA dermatosis (IEN) type, are described. IgA anti-keratinocyte cell surface antibodies reacted only with the uppermost epidermis in the SPD type but with the entire epidermis in the IEN type. A cDNA transfection test for desmocollins (Dsc) revealed that IgA antibodies of the SPD type reacted with Dsc1, but the IEN type did not react with any of the Dsc isoforms (Dsc1-3). ELISA for desmoglein 1 (Dsg1) and Dsg3 showed that neither of the cases had antibodies to Dsg - of either the IgG or IgA subtype. These results confirm that the autoantigen in SPD-type IgA pemphigus is Dsc1, whereas the antigen in most cases of IEN-type IgA pemphigus is unknown.

Aged↗

PubMed2002

Ultrasound biomicroscopic study of sclerotomy sites after implantation of sustained release drug devices.

BACKGROUND/AIMS: To evaluate the potential of ultrasound biomicroscopy (UBM) as a tool to study the precise location and changes of sclerotomy sites of the eye with an intraocular drug delivery device. METHODS: Eight eyes of six patients (13 sites) who received ganciclovir implants were examined by UBM. Examinations were performed 1-26 months (mean 12.8 months) postoperatively. Serial transverse and radial sections of the anterior ciliary body around the sclerotomy sites were obtained. RESULTS: The ganciclovir implant contour was successfully viewed using an UBM with high reflectivity. Three implants were deviated anteriorly and they were very close to the ciliary body and the lens (anterior deviation), while four implants were deviated posteriorly and away from the lens (posterior deviation). The other six implants were located at the appropriate position as intended. A solitary homogeneous mass with a medium reflectivity around the suture tab was observed at 12 out of 13 sites in seven eyes. Thick membranes extending from sclerotomy sites to the ora serrata were found at two sites in two eyes. CONCLUSION: UBM is helpful in detecting abnormal manifestations around ganciclovir implants and is a valuable tool to assess the changes of the sclerotomy sites of the sustained released intraocular devices.

Antiviral Agents↗

PubMed2001

Identification of protein fold and catalytic residues of gamma-hexachlorocyclohexane dehydrochlorinase LinA.

gamma-Hexachlorocyclohexane dehydrochlorinase (LinA) is a unique dehydrochlorinase that has no homologous sequence at the amino acid-sequence level and for which the evolutionary origin is unknown. We here propose that LinA is a member of a novel structural superfamily of proteins containing scytalone dehydratase, 3-oxo-Delta(5)-steroid isomerase, nuclear transport factor 2, and the beta-subunit of naphthalene dioxygenase-all known structures with different functions. The catalytic and the active site residues of LinA are predicted on the basis of its homology model. Nine mutants that carry substitutions of the proposed catalytic residues were constructed by site-directed mutagenesis. In addition to these, eight mutants that have a potential to make contact with the substrate were prepared by site-directed mutagenesis. These mutants were expressed in Escherichia coli, and their activities in crude extract were evaluated. Most of the features of the LinA mutants could be explained on the basis of the present LinA model, indicating its validity. We conclude that LinA catalyzes the proton abstraction via the catalytic dyad H73-D25 by a similar mechanism as described for scytalone dehydratase. The results suggest that LinA and scytalone dehydratase evolved from a common ancestor. LinA may have evolved from an enzyme showing a dehydratase activity.

Amino Acid Sequence↗

PubMed2001

Role of Flk-1 in mouse hematopoietic stem cells.

It was reported that human hematopoietic stem cells in bone marrow were restricted to the CD34(+)KDR(+) cell fraction. We found that expression levels of Flk-1, a mouse homologue of KDR, were low or undetectable in mouse Lin(-)c-Kit(+)Sca-1(+)CD34(low/-) cells as well as Hoechst33342(-) cells (side population), which have long-term reconstitution capacity. Furthermore, neither Flk-1(+)CD34(low/-) cells nor Flk-1(+)CD34(+) cells had long-term reconstitution capacity in mouse. Taken together with other observations using Flk-1-deficient mice, these results indicate that Flk-1 is essential for the development of hematopoietic stem cells in embryo but not for the function of hematopoietic stem cells in adult mouse bone marrow.

Animals↗

PubMed2001

Interleukin-18 stimulates hematopoietic cytokine and growth factor formation and augments circulating granulocytes in mice.

Because interleukin-18 (IL-18) is similar to IL-1 and is known to be involved in the hematopoietic progenitor cell growth, the effect of IL-18 on circulating cell populations was examined. Repeated administration of IL-18 induced significant amounts of neutrophilia in mice. In parallel, high levels of interferon-gamma (IFN-gamma), IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were detected in the serum of these mice. Interestingly, the cytokine profiles as well as the cell populations in circulation altered around 2 weeks after the beginning of IL-18 administration. A weak but definite eosinophilia was observed concurrently with the appearance of serum IL-5. Consistent with these observations, IL-18 induced secretion of IFN-gamma, GM-CSF, and IL-6 from splenocytes in culture. IL-18 also induced low levels of IL-5 in the splenocyte culture, which was inhibited by IL-12. However, markedly high levels of IL-5 were secreted into the culture medium when splenocytes from IFN-gamma-deficient mice were stimulated by IL-18. CD4(+) T cells strongly responded to IL-18 to secrete IL-5 and GM-CSF. IL-18 stimulated secretion of IL-6 and expression of G-CSF mRNA in splenic adherent cells. Expression of IL-18 receptors was detected in CD4(+) T cells and splenic adherent cells (macrophages). These results show that IL-18 stimulates CD4(+) T cells and macrophages to secrete IL-5, GM-CSF, IL-6, and granulocyte-colony stimulating factor in the absence of IL-12, which in turn induces hematopoietic cell proliferation causing neutrophilia and eosinophilia in mice.

Animals↗

PubMed2001

Definitive intraoperative very high-dose radiotherapy for localized osteosarcoma in the extremities.

PURPOSE: To evaluate the outcome and adverse effects in patients with osteosarcoma treated with very high-dose definitive intraoperative radiotherapy (IORT), with the intention of saving the affected limb. METHODS AND MATERIALS: Thirty-nine patients with osteosarcoma in their extremities were treated with definitive IORT. The irradiation field included the tumor plus an adequate wide margin and excluded the major vessels and nerves. Forty-five to 80 Gy of electrons or X-rays were delivered. The median follow-up of the surviving patients was 124 months. RESULTS: The cause-specific and relapse-free 5-year survival rate was 50% and 43%, respectively. Distant metastasis developed in 23 patients; 19 died and 4 were alive for >10 years. Nine local recurrences were found 4-29 months after IORT in the affected limb. No radiation-induced skin reaction or nerve palsy was observed in the patients treated with X-rays. Experiments using phantoms also confirmed that the scatter dose was below the toxic level in the IORT setting with X-rays. CONCLUSIONS: Very high-dose definitive IORT combined with preventive nailing and chemotherapy appeared to be a promising quality-of-life-oriented alternative to treating patients with osteosarcomas in the extremities, although the problem of recurrences from the surrounding unirradiated soft tissue remains to be solved.

Adolescent↗

PubMed2001

HLA-A26, HLA-B4002, HLA-B4006, and HLA-B4801 alleles predispose to adult T cell leukemia: the limited recognition of HTLV type 1 tax peptide anchor motifs and epitopes to generate anti-HTLV type 1 tax CD8(+) cytotoxic T lymphocytes.

Genetic risk for adult T cell leukemia (ATL) has been implicated by ethnic and familial segregation of ATL patients from HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). To clarify the genetic risk for ATL, we characterized HLA class I alleles of ATL patients and analyzed the anchor motifs of HTLV-1 peptides binding to HLA class I molecules, using 291 lines of anti-HTLV-1 CD8(+) cytotoxic T lymphocytes (CTLs) generated in vitro with a total of 165 synthetic peptides for HTLV-1 Tax and Env proteins. Allele frequencies of HLA-A*26, B*4002, B*4006, and B*4801 were significantly higher in ATL patients than in HAM/TSP patients and asymptomatic HTLV-1 carriers in southern Japan. CD8(+) CTL analysis revealed the HTLV-1 Tax peptide sequence to completely lack anchor motifs of peptides binding to HLA-A*26,B*4002, and B*4006 molecules but to possess one anchor for HLA-B*4801, while the HTLV-1 Env peptide sequence had many anchor motifs for HLA-A*26, B*4002, B*4006, and B*4801 molecules. Most ATL patients featured heterozygous HLA class I alleles composed of HLA-A*26, B*4002, B*4006, and B*4801, with a lower number of HTLV-1 Tax peptide anchor motifs and epitopes generating anti-HTLV-1 Tax CD8(+) CTLs than individuals possessing other HLA alleles. The relationship between Tax epitope and ATL incidence was verified by the significantly decreased number of HTLV-1 Tax epitopes in ATL patients compared with asymptomatic HTLV-1 carriers (p < 0.01) as well as late onset ATL patients (p < 0.001). These results indicate that HLA-A*26, B*4002, B*4006, and B*4801 alleles predispose to ATL because of the limited recognition of HTLV-1 Tax peptide anchor motifs and epitopes capable of generating anti-HTLV-1 Tax CD8(+) CTLs.

Adult↗

PubMed2001

BphS, a key transcriptional regulator of bph genes involved in polychlorinated biphenyl/biphenyl degradation in Pseudomonas sp. KKS102.

The bph genes in Pseudomonas sp. KKS102, which are involved in the degradation of polychlorinated biphenyl/biphenyl, are induced in the presence of biphenyl. In this study our goal was to understand the regulatory mechanisms involved in the inducible expression. The bph genes (bphEGF(orf4)A1A2A3BCD(orf1)A4R) constitute an operon, and its expression is strongly dependent on the pE promoter located upstream of the bphE gene. A bphS gene, whose deduced amino acid sequence showed homology with the GntR family transcriptional repressors, was identified at the upstream region of the bphE gene. Disruption of the bphS gene resulted in constitutive expression of bph genes, suggesting that the bphS gene product negatively regulated the pE promoter. The gel retardation and DNase footprinting analyses demonstrated specific binding of BphS to the pE promoter region and identified four BphS binding sites that were located within and immediately downstream of the -10 box of the pE promoter. The four binding sites were functional in repression because their respective elimination resulted in derepression of the pE promoter. The binding of BphS was abolished in the presence of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid, an intermediate compound in the biphenyl degradation pathway. We concluded that the negative regulator BphS plays a central role in the regulation of bph gene expression through its action at the pE promoter.

Amino Acid Sequence↗

PubMed2001

The effectiveness of an immobilization device in conformal radiotherapy for lung tumor: reduction of respiratory tumor movement and evaluation of the daily setup accuracy.

PURPOSE: To evaluate the daily setup accuracy and the reduction of respiratory tumor movement using a body frame in conformal therapy for solitary lung tumor. METHODS AND MATERIALS: Eighteen patients with a solitary lung tumor underwent conformal therapy using a body frame. The body shell of the frame was shaped to the patient's body contour. The respiratory tumor movement was estimated using fluoroscopy, and if it was greater than 5 mm, pressure was applied to the patient's abdomen with the goal of minimizing tumor movement. CT images were then obtained, and a treatment planning was made. A total dose of 40 or 48 Gy was delivered in 4 fractions. Portal films were obtained at each treatment, and the field displacements between them and the simulation films were measured for daily setup errors. The patients were repositioned if the setup error was greater than 3 mm. Correlations were analyzed between patient characteristics and the tumor movement, or the tumor movement reduction and the daily setup errors. RESULTS: Respiratory tumor movement ranged from 0 to 20 mm (mean 7.7 mm). The abdominal press reduced the tumor movement significantly from a range of 8 to 20 mm to a range of 2 to 11 mm (p = 0.0002). Daily setup errors were within 5 mm in 90%, 100%, and 93% of all verifications in left-right, anterior-posterior, and cranio-caudal directions, respectively. Patient repositioning was performed in 25% of all treatments. No significant correlation was detected between patient characteristics and tumor movement, tumor movement reduction, and the daily setup errors. CONCLUSIONS: The abdominal press was successful in reducing the respiratory tumor movement. Daily setup accuracy using the body frame was acceptable. Verification should be performed at each treatment in hypofractionated conformal therapy.

Adolescent↗

PubMed2001

Ny-ESO-1 expression and immunogenicity associated with transitional cell carcinoma: correlation with tumor grade.

NY-ESO-1 mRNA expression in transitional cell carcinoma was investigated by reverse transcription-PCR and immunohistochemistry. NY-ESO-1 mRNA was detected in 20 of 62 (32%) tumor specimens. There was a correlation between NY-ESO-1 expression and tumor grade: 0 of 4 (0%) grade 1 (G1), 6 of 26 (23%) grade 2 (G2), and 14 of 32 (44%) grade 3 (G3) tumors were NY-ESO-1 mRNA positive. Immunohistochemical analysis using NY-ESO-1-specific monoclonal antibody ES121 showed that 2 of 14 NY-ESO-1 mRNA-expressing G3 tumors were positive for NY-ESO-1. No NY-ESO-1 staining was observed in the panel of 30 G1 or G2 tumor specimens, including 6 NY-ESO-1 mRNA-positive cases. Sera from an expanded panel of 124 patients with transitional cell carcinoma were tested for the presence of NY-ESO-1 antibody. Seropositivity was observed in 9 of 72 (12.5%) patients with G3 tumors, whereas none of 52 patients with G1 or G2 tumors produced antibody against NY-ESO-1. In the 9 positive patients with NY-ESO-1 antibody, 4 had muscular invasive tumors, and 5 had carcinoma in situ.

Adult↗

PubMed2001

A novel regulator of G-protein signaling bearing GAP activity for Galphai and Galphaq in megakaryocytes.

The regulator of G-protein signaling (RGS) negatively regulates the alpha subunit of G proteins by accelerating their intrinsic guanosine triphosphatase (GTPase) activity. Here are reported the isolation and characterization of a novel mouse RGS, termed RGS18, which is a new member of RGS subfamily B. Northern blot analysis showed that RGS18 messenger RNA was detected predominantly in spleen and hematopoietic cells, and immunohistochemical studies demonstrated that RGS18 was expressed in megakaryocytes, platelets, granulocytes/monocytes, and, weakly, in hematopoietic stem cells, but not in lymphocytes or erythrocytes. Although various subcellular localizations of RGS have been reported, RGS18 was found to be localized in cytoplasm in megakaryocytes. In vitro binding assays of RGS18 with megakaryocyte cell lysates with or without AlF(4)(-) treatment demonstrated that RGS18 specifically binds to 2 alpha subunits of the G protein, Galphai and Galphaq. Furthermore, RGS18 clearly exhibited GTPase-activating protein (GAP) activity for Galphai and Galphaq but not for Galphas or Galpha12. In addition, chemokine stromal-derived factor 1 (SDF-1), which has been reported to stimulate megakaryocyte colony formation in the presence of thrombopoietin, affected the binding of RGS18 to Galphai but not to Galphaq. Therefore, the newly isolated RGS18 turned out to be a new member of the RGS family bearing GAP activity for Galphai, which might be stimulated by SDF-1 in megakaryocytes, as well as for Galphaq. Thus, RGS18 may play an important role in proliferation, differentiation, and/or migration of megakaryocytes.

Aluminum Compounds↗

PubMed2001

Isolation and characterization of acetoacetyl-CoA thiolase gene essential for n-decane assimilation in yeast Yarrowia lipolytica.

Yarrowia lipolytica is a yeast which can utilize n-alkane as a sole carbon source. We isolated a Y. lipolytica peroxisomal acetoacetyl-CoA thiolase gene, PAT1, by complementation of a mutant that cannot utilize n-decane as a sole carbon source. We found that the putative PAT1 product had conserved features of peroxisomal acetoacetyl-CoA thiolase. We showed that the PAT1 disruptant was not able to grow on n-decane, and that n-decane-inducible acetoacetyl-CoA thiolase activity largely depended on PAT1. The original mutant carried a mutation involving the replacement of Gly382 with Glu. This mutation inactivated the ability of PAT1 to complement the defective n-decane utilization of the disruptant. These results indicate that PAT1 encodes peroxisomal acetoacetyl-CoA thiolase and is essential for n-decane utilization in Y. lipolytica.

Acetyl-CoA C-Acetyltransferase↗

PubMed2001

Intestinal microflora are necessary for development of spontaneous adenocarcinoma of the large intestine in T-cell receptor beta chain and p53 double-knockout mice.

This study was conducted to confirm the hypothesis that intestinal microflora are required for the development of adenocarcinoma in the colon of the TCRbeta and p53 double-knockout (TCRbeta-/- p53-/-) mouse. Germ-free TCRbeta-/- p53-/- mice were produced. At 7 weeks of age, the animals were divided into two groups (n = 10/group), and one of these groups was conventionalized. Animals of both groups were subjected to histopathological examination for adenocarcinoma of the colon at 4 months of age. There was no development of adenocarcinoma of the colon among the germ-free mice, whereas in the conventionalized group, adenocarcinomas of the ileocecum and cecum were detected in 70% of animals. These results indicate the usefulness of the TCRbeta-/- p53-/- mouse as a colon cancer animal model that develops spontaneous adenocarcinoma of the colon early in life, and suggest that intestinal microflora play a major role in the development of adenocarcinoma of the colon in this animal model.

Adenocarcinoma↗

PubMed2001

Biochemical characterization of broad-specificity enzymes using multivariate experimental design and a colorimetric microplate assay: characterization of the haloalkane dehalogenase mutants.

The pH indicator dye-based colorimetric method and multivariate experimental design were used for the systematic biochemical characterization of the broad-specificity enzymes haloalkane dehalogenases. Halogenated compounds for characterization of the enzymes were selected using Principal Component Analysis. The substrates were characterised by 24 physico-chemical and structural descriptors. Thirty-four substrates were selected for testing out of 194 halogenated compounds. Relative activities determined using the optimised colorimetric microplate assay were validated against the catalytic constants determined by gas chromatography. The applicability of the assay was tested with F151L, F154L and F169L mutants of the haloalkane dehalogenase from Sphingomonas paucimobilis UT26.

Colorimetry↗

PubMed2001

Establishment and characterization of a human B cell line from the lung tissue of a patient with scleroderma; extraordinary high level of IL-6 secretion by stimulated fibroblasts.

Progressive systemic sclerosis is a connective tissue disease of unknown aetiology. This is the first study to demonstrate induction by a human B cell line of IL-6 secretion from fibroblasts. The cell line was established from lesional lung tissue of a patient with progressive systemic sclerosis. These cells, referred to as kon-1 cells, showed characteristics of pro-B cell by flow cytometry. Although kon-1 cells alone secreted a small amount of IL-6, a co-culture of kon-1 cells with normal lung fibroblasts significantly increased IL-6 levels. Whereas IL-6 mRNA was weakly expressed in kon-1 cells alone, it was clearly expressed in cells from the co-culture. Immunocytochemical identification of IL-6 showed localization in the cytoplasm of fibroblasts. IL-6 is a pleiotropic cytokine, essential for B cell differentiation, which has been shown to stimulate the production of collagen and glycosaminoglycan. Thus, abnormally augmented B cell proliferation and the inflammatory response stimulated by these cells may cause the fibrotic changes in patients with progressive systemic sclerosis.

B-Lymphocytes↗

PubMed2001

Sonochemical degradation of chlorinated hydrocarbons using a batch and continuous flow system.

The sonochemical degradation of chlorinated hydrocarbons such as 1,1,1-trichloroethane, trichloroethylene and tetrachloroethylene in aqueous solution was carried out in the batch and continuous flow systems at an ultrasonic frequency of 100kHz under an air atmosphere. In the batch experiment, the rate of degradation follows the order 1,1,1-trichloroethane>tetrachloroethylene>trichloroethylene, and the chlorinated hydrocarbon were readily degraded by ultrasonic irradiation. The experiments in the continuous flow system were performed in the range of volumetric flow rate from 7 to 30 x 10(-3)lmin(-1). The conversion of the chlorinated hydrocarbons at a steady-state of reactor depended on the volumetric flow rate. The yield of Cl(-) (as a measurement of mineralization of chlorinated hydrocarbons) was 70-90% of the chlorine atoms in the parent chlorinated hydrocarbon molecules. From the viewpoint of the scale-up process, the sonochemical degradation of trichloroethylene was simulated in a three stage reactor, and the conversion (>99%) in a third stage reactor was showed the good results that can be satisfied a desired water quality standard.

Environmental Pollution↗

PubMed2001

The use of a permanent magnetic resonance imaging system for radiotherapy treatment planning of bone metastases.

PURPOSE: To evaluate the usefulness of magnetic resonance (MR) imaging-based radiotherapy treatment planning (RTTP) for bone metastases in clinical applications. METHODS AND MATERIALS: MR imaging-based RTTP was carried out for 28 patients with bone metastases using a permanent magnetic MR unit. Twenty-three patients received MR imaging-assisted X-ray simulation, and five underwent MR simulation. In MR imaging-assisted X-ray simulation, the radiation fields defined by an X-ray simulator were modified based on MR information scanned in the exact treatment position using MR skin markers. In MR simulation, both isocenter position and field size were determined on MR images and projected onto the patient's skin. RESULTS: All lesions unclear on other imaging modalities could be clearly identified on MR imaging. Of the 23 patients receiving MR imaging-assisted X-ray simulation, modification of the original radiation field was necessary in 14 patients (extended in 9, reduced in 4, and completely changed in 1). In MR simulation, appropriate radiation fields could be easily and quickly determined using MR imaging. CONCLUSION: Methods for MR imaging-based RTTP were developed and clinically implemented for patients with bone metastases, and they were shown to be useful for improving the accuracy of the tumor location. They would provide better therapeutic/palliative benefit to particular patients with bone metastases and could also be applied to other lesions in the future.

Adult↗