Biomedical subjects

S Sato

Publications and source records attributed to S Sato.

At least 235 records · Page 13Linked to original sources

PubMed2001

Apparent diffusion coefficients and chemical species of neptunium (V) in compacted Na-montmorillonite.

Diffusion of neptunium (V) in compacted Na-montmorillonite was studied through the non-steady state diffusion method. In this study, two experimental attempts were carried out to understand the diffusion mechanism of neptunium. One was to establish the diffusion activation energy, which was then used to determine the diffusion process in the montmorillonite. The other was the measurement of the distribution of neptunium in the montmorillonite by a sequential batch extraction. The apparent diffusion coefficients of neptunium in the montmorillonite at a dry density of 1.0 Mg m-3 were from 3.7 x 10(-12) m2 s-1 at 288 K to 9.2 x 10(-12) m2 s-1 at 323 K. At a dry density of 1.6 Mg m-3, the apparent diffusion coefficients ranged between 1.5 x 10(-13) m2 s-1 at 288 K and 8.7 x 10(-13) m2 s-1 at 323 K. The activation energy for the diffusion of neptunium at a dry density of 1.0 Mg m-3 was 17.5 +/- 1.9 kJ mol-1. This value is similar to those reported for diffusion of other ions in free water, e.g., 18.4 and 17.4 kJ mol-1 for Na+ and Cl-, respectively. At a dry density of 1.6 Mg.m-3, the activation energy was 39.8 +/- 1.9 kJ mol-1. The change in the activation energy suggests that the diffusion process changes depending on the dry density of the compacted montmorillonite. A characteristic distribution profile was obtained by the sequential extraction procedure for neptunium diffused in compacted montmorillonite. The estimated fraction of neptunium in the pore water was between 3% and 11% at a dry density of 1.6 Mg m-3 and at a temperature of 313 K. The major fraction of the neptunium in the montmorillonite was identified as neptunyl ions sorbed on the outer surface of the montmorillonite. These findings suggested that the activation energy for diffusion and the distribution profile of the involved nuclides could become powerful parameters in understanding the diffusion mechanism.

Bentonite↗

PubMed2001

Diffusion mechanism of chloride ions in sodium montmorillonite.

For safety assessment of geological disposal of HLW, it is necessary to understand the diffusion mechanism of radionuclides in compacted bentonite. In this study, the diffusion behavior of chloride ions in compacted montmorillonite was studied from the viewpoints of the activation energy for apparent diffusion and the basal spacing of the compacted montmorillonite. A unique change in the activation energy as a function of the dry density of the montmorillonite was found. The activation energy decreased from 17.4 to 13.5 kJ mol-1 as the dry density increased from 0.7 to 1.0 Mg m-3 and increased to 25.1 kJ mol-1 at dry densities above 1.0 Mg m-3. The basal spacing of 1.88 nm, corresponding to the three-water layer hydrate state, was not observed by X-ray diffraction (XRD) until the dry density increased to 1.0 Mg m-3, where the minimum activation energy was obtained. On the other hand, a basal spacing of 1.56 nm, corresponding to the two-water layer hydrate state, was observed at the dry densities of 1.4 Mg m-3 and above, where the activation energies were more than 22 kJ mol-1. These experimental results suggest that there are at least two additional diffusion processes that can raise or reduce the activation energy and are affected by water in the region adjacent to the montmorillonite surfaces. If the "Grahame model" can be introduced to describe the electrical double layer, surface diffusion will be considered the possible predominant diffusion process, even for anions like chloride ions.

Anions↗

PubMed2001

Increased von Willebrand factor in the endocardium as a local predisposing factor for thrombogenesis in overloaded human atrial appendage.

OBJECTIVES: We investigated immunoreactive von Willebrand factor (vWF), a platelet adhesion molecule, in the endocardial endothelium and its relationship to thrombogenesis in the human atrial appendage. BACKGROUND: Intra-atrial thrombogenesis is generally thought to be induced by blood stasis in the atrial appendage involved with atrial fibrillation (AF). Little attention has been paid to alterations of the endocardial endothelium on which the thrombus develops. METHODS: Atrial appendage tissue was obtained at heart surgery or at autopsy from AF and non-AF cardiac patients and from noncardiac patients. Immunohistochemistry for endothelial cell markers including vWF, CD31, CD34 and endothelial nitric oxide synthase (eNOS) and platelet glycoprotein Ib/IX or IIb/IIIa was performed and semiquantitatively graded. RESULTS: In contrast to the apparent immunostaining for CD31, CD34 and eNOS, only focal or little immunoreactive vWF was seen in the endocardium of noncardiac patients. Immunoreactive vWF in the endocardial endothelium was increased in most cardiac patients, particularly in the left, but not in the right, atrial appendage of patients with mitral valvular disease, irrespective of whether AF was present. Platelet adhesion/thrombus formation in the endocardium was found in limited sites in which the overlying endothelium was deficient in eNOS and CD34. When warfarin-treated cases were excluded, there was a significant correlation between the immunohistochemical grade for vWF and the degree of platelet adhesion/thrombus formation in the endocardium. CONCLUSIONS: Immunoreactive vWF in the endocardial endothelium was increased in overloaded human atrial appendage, which may be a local predisposing factor for intraatrial thrombogenesis.

Adult↗

PubMed2001

Elevated serum levels of soluble L-selectin in patients with systemic sclerosis declined after intravenous injection of lipo-prostaglandin E1.

To determine whether serum soluble L-selectin (sL-selectin) levels are elevated in patients with systemic sclerosis (SSc) and whether serum sL-selectin levels change after treatment with lipo-prostaglandin E1 (lipo-PGE1), serum sL-selectin levels were examined by ELISA in patients with SSc (n=24), psoriasis vulgaris (n=22), and contact dermatitis (n=9), as well as normal control subjects (n=26). In five patients with SSc, serum sL-selectin levels were examined before and after intravenous injections of lipo-PGE1. Serum sL-selectin levels were significantly increased in patients with SSc (P<0.01) than those in normal control subjects. The elevated serum sL-selectin levels in patients with SSc significantly decreased 1 day (P<0.05), 7 days (P<0.05) and 14 days (P<0.05) after starting the treatment with lipo-PGE1. These results suggest that L-selectin may be involved in the disease process in SSc, and lipo-PGE1 may alter some inflammatory events in SSc.

Adolescent↗

PubMed2001

Serum levels of interleukin-6 and interleukin-10 correlate with total skin thickness score in patients with systemic sclerosis.

Various growth factors and cytokines have been suggested to play a central role in initiating and developing fibrosis in systemic sclerosis (SSc). To determine which serum levels of soluble mediators are the most relevant to the degree of skin sclerosis in SSc, serum levels of various soluble mediators were examined by ELISA and correlated with skin thickening that was measured using modified Rodnan total skin thickness scoring (TSS) system. Serum levels of IL-4, IL-12, IL-13, tumor necrosis factor-alpha, connective tissue growth factor (CTGF), vascular endothelial growth factor, monocyte chemotactic protein-1, macrophage inflammatory protein-1beta, soluble IL-6 receptor, and soluble L-selectin were higher in SSc patients than normal controls. Levels of IL-6, IL-10, and CTGF in patients with diffuse cutaneous SSc were higher than patients with limited cutaneous SSc and controls. Serum levels of IL-6 and IL-10 positively correlated with TSS in patients with SSc (r=0.625, P<0.0001 and r=0.663, P<0.0001, respectively). In addition, IL-10 levels significantly correlated with pulmonary fibrosis. Thus, serum levels of IL-6 and IL-10 most strongly reflect the extent of skin thickening in SSc, suggesting that levels of IL-6 and IL-10 are useful serological indicators for skin fibrosis in SSc.

Adult↗

PubMed2001

Expression of cementum-derived attachment protein in bovine tooth germ during cementogenesis.

Cementum-derived attachment protein (CAP) is a 56 kDa collagenous protein that promotes attachment of mesenchymal cells. Previous studies have shown that the presence of CAP is restricted to cementum in adult human tissues. In this study, we report generation of a monoclonal antibody against CAP and its use for the investigation of CAP in developing bovine tooth germs. Mice were immunized with CAP purified from bovine cementum, and a monoclonal antibody, 3G9, was produced. Immunohistochemical staining of bovine tooth germ at root forming stage using 3G9 antibody showed that the tissue distribution of CAP expression was limited to cementum matrix and cementoblasts during cementogenesis. Alveolar bone did not stain with the 3G9 antibody, whereas anti-type I collagen stained positively. CAP was purified from bovine tooth germs with immunoaffinity purification using the 3G9 antibody. Examination of the immunoaffinity-purified fraction showed that CAP existed in tooth germ as a 65 kDa protein. The protein was susceptible to bacterial collagenase. To investigate the possible biological function of CAP during cementogenesis, we isolated dental follicle cells from the bovine tooth germ, and showed that they adhered to surfaces containing CAP. These data demonstrate that CAP is expressed by bovine cementoblasts as a 65 kDa protein and that the CAP may have a function in cementogenesis.

Animals↗

PubMed2001

Substrate recognition by ADAR1 and ADAR2.

RNA editing catalyzed by ADAR1 and ADAR2 involves the site-specific conversion of adenosine to inosine within imperfectly duplexed RNA. ADAR1- and ADAR2-mediated editing occurs within transcripts of glutamate receptors (GluR) in the brain and in hepatitis delta virus (HDV) RNA in the liver. Although the Q/R site within the GluR-B premessage is edited more efficiently by ADAR2 than it is by ADAR1, the converse is true for the +60 site within this same transcript. ADAR1 and ADAR2 are homologs having two common functional regions, an N-terminal double-stranded RNA-binding domain and a C-terminal deaminase domain. It is neither understood why only certain adenosines within a substrate molecule serve as targets for ADARs, nor is it known which domain of an ADAR confers its specificity for particular editing sites. To assess the importance of several aspects of RNA sequence and structure on editing, we evaluated 20 different mutated substrates, derived from four editing sites, for their ability to be edited by either ADAR1 or ADAR2. We found that when these derivatives contained an A:C mismatch at the editing site, editing by both ADARs was enhanced compared to when A:A or A:G mismatches or A:U base pairs occurred at the same site. Hence substrate recognition and/or catalysis by ADARs could involve the base that opposes the edited adenosine. In addition, by using protein chimeras in which the deaminase domains were exchanged between ADAR1 and ADAR2, we found that this domain played a dominant role in defining the substrate specificity of the resulting enzyme.

Adenosine Deaminase↗

PubMed2001

Assessment of tear concentrations on therapeutic drug monitoring. II. Pharmacokinetic analysis of valproic acid in guinea pig serum, cerebrospinal fluid, and tears.

PURPOSE: To quantitatively describe the pharmacokinetics of valproic acid (VPA) in guinea pig serum (total [Cf+b] and free [Cf]), cerebrospinal fluid (CSF) [C]CSF and tears [C]T using a simple kinetic model, and to examine whether [Cf] and [C]CSF can be predicted by [C]T using the resulting pharmacokinetic parameters. METHODS: [Cf+b], [Cf], [C]CSF and [C]T were determined after bolus i.v. injection of 10 or 20 mg/kg VPA using GC/ECNCI/MS. RESULTS: [Cf+b] could be quantitatively described by a two compartment model with linear elimination kinetics. [Cf] was separately analyzed using multi-exponential equations. [C]CSF was analyzed using a simple kinetic model in which the CSF compartment is independently connected with the serum compartment by the apparent diffusion constants (KINCSF and KOUTCSF). [C]T was analyzed using the same simple kinetic model used for [C]CSF. The values of [C]CSF and [Cf] in the steady state can be represented by the following equations; [C]CSF = KINCSF/KOUTCSF x [Cf], [Cf] = KOUT/KINT x [C]T, and indicating that [Cf] and [C]CSF can be predicted by [C]T using the resulting pharmacokinetic parameters. CONCLUSIONS: The measurement of [C]T which can be collected non-invasively and estimated the pharmacokinetic parameters for [Cf], [C]CSF, and [C]T might be a very useful method for TDM of VPA.

Animals↗

PubMed2001

Identification of a novel allele HLA-B*7805 in a Japanese female.

A new HLA-B*78 allele, B*7805, was identified in a healthy Japanese female. The results of her serological HLA class I typing showed an unusual Bw4/Bw6 pattern with strongly positive reactivity to anti-Bw6, i.e. A24, -, B52, -, Bw4, Bw6. In DNA typing, she was typed as A*24, -, B*52, B*78-like, Cw1202, -, (Bw4, Bw6). Cloning and sequencing of exon 2 and exon 3 of her B locus genes revealed a new allele B*7805. The cloned B*7805 differed from B*78021 by three nucleotide substitutions in exon 2 at position 259 (A to G), 261 (C to G) and 272 (A to C), and contained sequences defining Bw6 motif in the region of codon 77 to 83.

Alleles↗

PubMed2001

Clinical application of a new compact CT system to assess 3-D images for the preoperative treatment planning of implants in the posterior mandible A case report.

When treatment planning before placing dental implants in the posterior region of the mandible, the locations of the inferior alveolar nerve and mental foramen need to be ascertained, as they determine the bone height available and the implant length selected. The purpose of this study was to introduce the clinical application of a newly developed compact computed tomography system (Ortho-CT) to assess three-dimensional (3-D) images for the preoperative treatment planning of implants in the posterior region of the mandible. To evaluate the 3-D images, we scanned using the Ortho-CT system the mandible with a radiopaque template placed in the posterior region. The Ortho-CT images provided excellent information for evaluating the morphology of the mandible, and for showing the location of the inferior alveolar nerve, mental foramen and the relationship of the template to the bone. We consider that Ortho-CT is a useful aid to preoperative treatment planning of implant therapy in the mandible.

Contrast Media↗

PubMed2001

Development of pigment cells in the brain of ascidian tadpole larvae: insights into the origins of vertebrate pigment cells.

In vertebrates, melanins produced in specialized pigment cells are required for visual acuity, camouflage, sexual display and protection from ultra violet (UV) radiation. There are three pigment cell types that are classified based on their distinct embryonic origins. Retinal pigment epithelium (RPE) cells originate from the outer layer of the optic cup. Pigment cells of the pineal organ are formed from the developing diencephalon. Melanocytes are derived from the neural crest unique to vertebrate embryos. Some of these pigment cells also play roles that are independent of the activity of tyrosinase, the key melanogenesis enzyme, or melanin: production of substrate(s) for catecholamine synthesis, maintenance of endolymph composition in the cochlea, maintenance of photoreceptor cells in the retina and retinoid metabolism essential for the visual cycle. To deduce the evolutionary origins of vertebrate pigment cells and a possible archetypal genetic circuitry, which may have been modified and utilized to generate multiple pigment cell types, comparison of developmental mechanisms of pigment cells between vertebrates and closely related invertebrate ascidians are proposed to provide useful information. The tadpole-type larva of ascidians possesses two melanin-containing pigment cells, termed the otolith and ocellus pigment cells, in the brain that are believed to be required for photo- and geotactic responses during swimming. In this review, current knowledge on the development of the two ascidian pigment cells is summarized, i.e. complete cell lineage, structure and expression of genes encoding two melanogenesis enzymes, and molecular developmental mechanisms involving BMP-CHORDIN antagonism, and possible evolutionary relationships between ascidian and vertebrate pigment cells are discussed.

Animals↗

PubMed2001

Shifted positioning of the anticodon nucleotide residues of amber suppressor tRNA species by Escherichia coli arginyl-tRNA synthetase.

Cytidine in the anticodon second position (position 35) and G or U in position 36 of tRNAArg are required for aminoacylation by arginyl-tRNA synthetase (ArgRS) from Escherichia coli. Nevertheless, an arginine-accepting amber suppressor tRNA with a CUA anticodon (FTOR1Delta26) exhibits suppression activity in vivo [McClain, W.H. & Foss, K. (1988) Science, 241, 1804-1807]. By an in vitro kinetic study with mutagenized tRNAs, we showed that the arginylation of FTOR1Delta26 involves C34 and U35, and that U35 can be replaced by G without affecting the activity. Thus, the positioning of the essential nucleotides for the arginylation is shifted to the 5' side, by one residue, in the suppressor tRNAArg. We found that the shifted positioning does not depend on the tRNA sequence outside the anticodon. Furthermore, by a genetic method, we isolated a mutant ArgRS that aminoacylates FTOR1Delta26 more efficiently than the wild-type ArgRS. The isolated mutant has mutations at two nonsurface amino-acid residues that interact with each other near the anticodon-binding site.

Amino Acid Sequence↗

PubMed2001

Functional conservation of the promoter regions of vertebrate tyrosinase genes.

Tyrosinase is the key enzyme for synthesizing melanin pigments, which primarily determine mammalian skin coloration. Considering the important roles of pigments in the evolution and the adaptation of vertebrates, phylogenetic changes in the coding and flanking regulatory sequences of the tyrosinase gene are particularly intriguing. We have now cloned cDNA encoding tyrosinase from Japanese quail and snapping turtle. These nonmammalian cDNA are highly homologous to those of the mouse and human tyrosinases, whereas the 5' flanking sequences are far less conserved except for a few short sequence motifs. Nevertheless, we demonstrate that the 5' flanking sequences from the quail or turtle tyrosinase genes are capable of directing the expression of a fused mouse tyrosinase cDNA when introduced into cultured mouse albino melanocytes. This experimental method, which reveals the functional conservation of regulatory sequences in one cell type (the melanocyte), may be utilized to evaluate phylogenetic differences in mechanisms controlling specific gene expression in many other types of cells. We also provide evidence that the 5' flanking sequences from these nonmammalian genes are functional in vivo by producing transgenic mice. Phylogenetic changes of vertebrate tyrosinase promoters and the possible involvement of conserved sequence motifs in melanocyte-specific expression of tyrosinase are discussed.

5' Flanking Region↗

PubMed2001

Elevated serum L-selectin levels and decreased L-selectin expression on CD8(+) lymphocytes in systemic sclerosis.

L-selectin is expressed on most circulating leucocytes and mediates leucocyte rolling on endothelium at sites of inflammation. Following rolling or activation of leucocytes, cell surface L-selectin is released as soluble L-selectin (sL-selectin). In the present study, we assessed serum levels of sL-selectin by ELISA and blood leucocyte L-selectin expression by flow cytometry in patients with systemic sclerosis (SSc). Serum levels of sL-selectin in patients with SSc (n = 51) were significantly higher than in normal controls (n = 30) while sL-selectin levels were similar for systemic lupus erythematosus patients (n = 20) and normal controls. Furthermore, SSc patients with elevated sL-selectin levels had inflammatory joint involvement, pitting scar/ulcers, and diffuse pigmentation more frequently than those with normal sL-selectin levels. The frequency of L-selectin(+) population among CD8(+) T cells was significantly decreased in SSc patients (n = 30) compared with normal controls (n = 20), while that among CD4(+) T cells, B cells, monocytes, and neutrophils was similar for SSc patients and normal controls. These suggest that elevated sL-selectin levels and decreased frequency of L-selectin+ CD8(+) T cells in SSc patients may be involved in inflammation associated with SSc.

Adolescent↗

PubMed2001

Inhibition of adhesion of food-borne pathogens to Caco-2 cells by Lactobacillus strains.

AIMS: To select adhesive strains among strains of Lactobacillus and to apply them to inhibit adhesion of food-borne pathogens. METHODS AND RESULTS: Twelve Lactobacillus strains (10 from intestine) were examined for adhesion using Caco-2 cell cultures. The two most adhesive strains, Lactobacillus crispatus JCM 8779 and Lact. reuteri JCM 1081, were used to test antiadhesion activity against enterotoxigenic Escherichia coli, Salmonella typhimurium and Enterococcus faecalis strains. Adhesion of the pathogens was inhibited by both Lactobacillus strains. Adhesion of Ent. faecalis was especially strongly inhibited by JCM 8779. Although antimicrobial activity was not detected in the culture supernatant fluid by agar well diffusion assay, the supernatant fluid obtained from the harvested JCM 8779 cell suspension showed bactericidal activity against Ent. faecalis. CONCLUSION: The strong antiadhesion activity of JCM 8779 against Ent. faecalis appears to be due to the combined effect of both bactericidal activity and competition for attachment site. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report that Lact. crispatus produces a bactericidal substance.

Antibiosis↗

PubMed2001

Zinc supplementation enhances the response to interferon therapy in patients with chronic hepatitis C.

We evaluated the synergistic effect of zinc supplementation on the response to interferon (IFN) therapy in patients with intractable chronic hepatitis C in a pilot study using natural IFN-alpha with or without zinc. No clinical differences were observed between patients treated with IFN alone (n=40) and IFN with polaprezinc (IFN + Zn, n=35). All patients were positive for HCV genotype Ib and had more than 105 copies of the virus/mL serum. Ten million units of natural IFN-alpha was administered daily for 4 weeks followed by the same dose every other day for 20 weeks. In the IFN + Zn group, patients received an additional dose of 150 mg/day polaprezinc orally throughout the 24-week IFN course. No additional side-effects of polaprezinc were noted but four out of 40 IFN alone treatment and three out of 35 IFN + Zn group withdrew because of side-effects. Complete response (CR) was defined as negative HCV RNA in the serum on PCR and normal aminotransferase level 6 months after therapy. Incomplete response (IR) was normal liver enzyme and positive serum HCV RNA. Both of them were evaluated at the 6 months after the completion of the treatment. Patients with higher levels of serum HCV (more than 5 x 105 copies/mL) had little response in both treatment groups. Patients with moderate amount of HCV (105 to 4.99 x 105/mL) showed high response rates in combination group (CR: 11/27, 40.7%; CR + IR 15/27, 64.3%), better than IFN alone (CR: 2/15, 18.2%; CR + IR: 2/15, 18.2%). Serum zinc levels were higher in patients with IFN + Zn group than in the IFN group. Our results indicate that zinc supplementation enhances the response to interferon therapy in patients with intractable chronic hepatitis C.

Adult↗

PubMed2001

Cases of Alzheimer's disease due to deletion of exon 9 of the presenilin-1 gene show an unusual but characteristic beta-amyloid pathology known as 'cotton wool' plaques.

The pattern of deposition of amyloid beta protein (Abeta) was investigated, using the monoclonal antibodies BA27 and BC05 detecting the C-terminal species Abeta40 and Abeta42(43), in six cases of Alzheimer's disease (AD) due to deletions in exon 9 of PS-1 gene. These cases are characterized histologically by the presence of very large rounded plaques within the frontal cortex, known as 'cotton wool' plaques, composed of both Abeta40 and Abeta42(43) that are relatively free from neuritic changes and glial cell components, and usually devoid of a compact amyloid core. In the cerebellum the plaques are almost entirely of a compact type, again composed of Abeta40 and Abeta42(43), with only few diffuse Abeta42(43) containing plaques. The area fraction of Abeta40, and the ratio between Abeta40 and Abeta42(43), in frontal cortex was significantly higher than that seen in other cases of AD due to different PS-1 mutations, or in cases of sporadic AD, all of similar APO E genotype. The area fractions of Abeta42(43), however, did not significantly differ between these three groups. The unusual nature of the Abeta deposition in these cases may reflect the uniqueness of the mutation, which results in a failure to constitutively cleave the PS-1 holoprotein into its active form, and the effect this might have on APP trafficking and catabolism.

Adult↗

PubMed2001

Comparative study of self-expandable metallic stent and bypass surgery for inoperable esophageal cancer.

We evaluated the effect of two different therapies for 23 patients with inoperable esophageal cancer, of whom 13 patients underwent placement of a metallic stent and 10 received bypass surgery. We newly defined the improved level of food intake and the effective rate based on the grade of the patient's status in order to evaluate objectively. Although the effect of stent placement was significantly better than that of bypass surgery, there were no significant differences in the improved level of food intake and the effective rate between the two groups. Four out of 10 patients in the bypass group had suture insufficiency, resulting in no oral intake and a fatal outcome. In addition, the ratio of survival period of ability to ingest orally and in-hospital mortality was significantly favorable in the stent group compared with the bypass group. In conclusion, stent placement should be the first choice for inoperable malignant stenosis or esophageal fistula.

Adult↗