Biomedical subjects
Publications and source records attributed to S Yamasaki.
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We report the formation processes of interface dangling bonds (Pb centers) during initial oxidation of a clean Si(111) surface using an ultrahigh-vacuum electron-spin-resonance technique. At the oxidation of one or two Si layer(s), the Pb center density reached around 2.5-3.0 x 10(12) cm(-2), which is the same density as in the case of thick SiO2. This result shows that the Pb center density does not originate from the long-range accumulation of the structural stress between two materials, but from the chemical reactions of oxidation within a few Si atomic layers.
OBJECTIVES: Our recent work showed that fibroblast-like synovial cells (FLS) could differentiate into adipocyte-like cells in vitro in response to stimulation with peroxisome proliferator-activated receptor gamma (PPAR gamma) ligand. The aim of the present study was to determine the role of cytokines in the regulation of FLS differentiation to adipocyte-like cells. METHODS: FLS isolated from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and from normal synovial tissues were incubated with the synthetic PPAR gamma ligand troglitazone to induce adipocyte-like differentiation of the cells. RESULTS: Production of interleukin (IL)-6, IL-8 and matrix metalloproteinase-3 was reduced in adipocyte-like cells compared with FLS. DNA binding activity of nuclear factor kappa B (NF-kappa B) was clearly inhibited in adipocyte-like cells. Cultivation of FLS with interferon gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) or IL-1 beta inhibited the expression of PPAR gamma as well as CCAAT/enhancer binding protein (C/EBP) nuclear activity, and thus suppressed adipocyte-like cell differentiation in vitro. CONCLUSION: Our results indicate the importance of PPAR gamma and C/EBP in adipocyte-like cell differentiation of FLS and that the process is influenced by inflammatory cytokines, and suggest that the proinflammatory character of FLS in patients with RA is diminished during adipocyte-like cell differentiation.
Shiga toxin producing-Escherichia coli (STEC) has not yet been identified as an important aetiologic agent of human disease in Thailand. To evaluate the potential for STEC to contribute to human disease in Thailand, 139 fecal samples were collected from healthy cattle from five different provinces and analysed by genotypic and phenotypic methods for STEC. Of 139 samples, 27 (19.4%) were positive for stx1 and/or stx2 by multiplex polymerase chain reaction, or for O157 lipopolysaccharide (LPS) by immunoassay. Isolates positive for stx and/or O157 were subdivided into 49 strains that varied in the presence of the virulence determinants stx1+/stx2+ (22 strains), stx2+ (22 strains), stx1+ (4 strains), and O157 LPS (1 strain). Within these 49 distinguishable strains, other virulence determinants varied as follows: hlyA+ (77.6%), eae+ and tir+ (4.1%), and katP+ (6.12%). The most predominant profile (22 isolates) was stx1+/stx2+, eae-, tir-, etpD-, hlyA+, katP-. For further characterization of the isolated strains by two molecular typing assays, plasmid profiles and ERIC PCR were performed. The results suggest that the genetic and phenotypic profiles of STEC associated with human disease are not prevalent at this time in cattle in Thailand.
With the increasing frequency of haploidentical transplantation, it is becoming more important to establish the degree of HLA mismatch that can be accepted. We retrospectively analyzed clinical data of 50 adult Japanese patients with high-risk hematologic malignancies who underwent allogeneic peripheral blood stem cell transplantation (PBSCT) from two- or three-loci-mismatched related donors with HLA class I and II gene disparities in the graft-versus-host direction. They were treated at 20 transplant centers between 1996 and 2002. In all, 18 patients received unmanipulated PBSC, while 32 received purified CD34+ blood cells. Conventional (n=31) or reduced-intensity (n=19) conditioning regimens were used. Of the 39 patients (78%) who survived for > or =28 days after transplant, 37 (95%) achieved neutrophil engraftment, while graft failure and rejection occurred in two of 39 (5%) and three of 37 (8%) patients, respectively. Stepwise Cox regression analysis revealed a significantly lower incidence of grades II-IV acute GVHD in patients receiving purified CD34+ cells (hazard ratio 0.32; 95% CI 0.12-0.84; P=0.022). By 1 year post transplant, 28 patients (56%) had died of transplant-related problems, including infectious complications (30%). Although the number of patients is small, our data suggest that transplant-related problems, particularly infectious complications, are major obstacles to the success of this therapy.
A comprehensive study was performed to examine incidence, species distribution, drugs sensitivity, virulence genes and molecular fingerprints of Aeromonas species isolated from patients with acute diarrhoea over a period of 2 years in Kolkata, India. Following the Aerokey II scheme, more than 95 % of strains were identified to species level. Seven different species were encountered in this study, with Aeromonas caviae being dominant, followed by Aeromonas hydrophila and Aeromonas veronii biovar sobria. Thirty different serotypes were encountered, with O16, O83 and O85 being dominant, but no serotype was associated specifically with a single species. The majority of Aeromonas strains exhibited multidrug resistance. The alt and act genes, which encode heat-labile cytotonic and cytotoxic enterotoxins, were respectively found in 71.9 and 20.1 % of strains examined. Only 2.4 % of strains carried the heat-stable cytotonic enterotoxin (ast) gene. The hlyA gene was found in 28 % of Aeromonas strains. With few exceptions, genomic diversity of Aeromonas strains belonging to the same serotype was observed by random amplification of polymorphic DNA PCR and ribotyping. Different species of Aeromonas and different clones of Aeromonas species seem to be associated with hospitalized cases of diarrhoea in Kolkata, India.
We examined the role of osteoprotegerin (OPG) on tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in rheumatoid fibroblast-like synovial cells (FLS). OPG protein concentrations in synovial fluid from patients with rheumatoid arthritis (RA) correlated with those of interleukin (IL)-1beta or IL-6. A similar correlation was present between IL-1beta and IL-6 concentrations. Rheumatoid FLS in vitro expressed both death domain-containing receptors [death receptor 4 (DR4) and DR5] and decoy receptors [decoy receptor 1 (DcR1) and DcR2]. DR4 expression on FLS was weak compared with the expression of DR5, DcR1 and DcR2. Recombinant TRAIL (rTRAIL) rapidly induced apoptosis of FLS. DR5 as well as DR4 were functional with regard to TRAIL-mediated apoptosis induction in FLS; however, DR5 appeared be more efficient than DR4. In addition to soluble DR5 (sDR5) and sDR4, OPG administration significantly inhibited TRAIL-induced apoptogenic activity. OPG was identified in the culture supernatants of FLS, and its concentration increased significantly by the addition of IL-1beta in a time-dependent manner. Neither IL-6 nor tumour necrosis factor (TNF)-alpha increased the production of OPG from FLS. TRAIL-induced apoptogenic activity towards FLS was reduced when rTRAIL was added without exchanging the culture media, and this was particularly noticeable in the IL-1beta-stimulated FLS culture; however, the sensitivity of FLS to TRAIL-induced apoptosis itself was not changed by IL-1beta. Interestingly, neutralization of endogenous OPG by adding anti-OPG monoclonal antibody (MoAb) to FLS culture restored TRAIL-mediated apoptosis. Our data demonstrate that OPG is an endogenous decoy receptor for TRAIL-induced apoptosis of FLS. In addition, IL-1beta seems to promote the growth of rheumatoid synovial tissues through stimulation of OPG production, which interferes with TRAIL death signals in a competitive manner.
OBJECTIVE: To investigate anti-apoptogenic mechanism of transforming growth factor beta1 (TGFbeta1) towards synovial cells. METHODS: Isolated synovial cells, treated or not with TGFbeta1, were cultured in the presence or absence of anti-Fas IgM, proteasome inhibitor Z-Leu-Leu-Leu-aldehyde (LLL-CHO), etoposide, or C2-ceramide. After cultivation, apoptosis of synovial cells was examined by the presence of hypodiploid DNA(+) cells, the presence of terminal deoxy (d)-UTP nick end labelling(+) cells (TUNEL(+) cells), activation of caspases, and disruption of mitochondrial transmembrane potential (DeltaPsim). RESULTS: Activation of caspase-9 and DeltaPsim was found in anti-Fas IgM treated synovial cells. The increment of both hypodiploid DNA(+) cells and TUNEL(+) cells accompanied by the activation of caspase-8 and caspase-3 was also determined in anti-Fas IgM treated synovial cells. These hallmarks for apoptosis induced by anti-Fas IgM were significantly suppressed in TGFbeta1 treated synovial cells. LLL-CHO, etoposide, and C2-ceramide also caused DeltaPsim, the increment of both hypodiploid DNA(+) cells and TUNEL(+) cells, and the activation of both Leu-Glu-His-Asp ase (LEHDase; caspase-9 like activity) and Asp-Glu-Val-Asp ase (DEVDase; caspase-3 like activity) in synovial cells. As determined in anti-Fas IgM treatment, TGFbeta1 significantly reduced apoptotic cell death of synovial cells induced by the above chemicals. CONCLUSIONS: The protective effect of TGFbeta1 for mitochondrial homoeostasis may be important in the anti-apoptogenic function of TGFbeta1 for synovial cells.
Possible diabetes mellitus-induced changes in hippocampal monoaminergic activities were studied to understand the relationships between neurotransmitter levels and various abnormalities in freely moving diabetic rats. We used both experimentally (STZ rats) and spontaneously diabetic rats (WBN/Kob rats) as the diabetic animal model, and compared the findings with those obtained from non-diabetic rats (C rats). Measurement of neurotransmitters (serotonin and dopamine) was carried out using an in vivo microdialysis method. We found that: 1) the basal level of serotonin in the hippocampus was lowest in WBN rats, followed by STZ rats, then by C rats. The level of serotonin in WBN rats was about a half of that in C rats; 2) the basal level of dopamine was also significantly lower in the diabetic WBN and STZ rats than in C rats. The data show that diabetes mellitus decreases in the monoamine release from the hippocampus in both experimentally and spontaneously diabetic rats.
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While searching for Escherichia coli O157 in the aquatic environment of Calcutta using an immunodetection procedure, we fortuitously detected five strains of Citrobacter braakii, which cross-reacted with the commercially available O157 polyvalent antiserum. The five C. braakii isolates gave positive results when a sensitive dot-ELISA was performed with E. coli O157 monoclonal antibody. Further, the O157 monoclonal antibody recognized the bands of proteinase K treated whole cells of lipopolysaccharide of all the C. braakii isolates. Apart from weak reactions with two or three of the DNA probes, all the C. braakii strains did not hybridize with the other probes spanning the minimum region required for O157 O-antigen biosynthesis. These strains did not possess any of the virulence genes that are commonly found in the Shiga toxin-producing E. coli (STEC) specially the serotype O157: H7. Therefore, it appears that the serological cross-reaction between C. braakii and E. coli O157 antiserum is based on structural mimicry between the O-polysaccharide of C. braakii and E. coli O157.
We investigated effects of variations in the cellular composition of G-CSF-mobilized peripheral blood progenitor cell (G-PBPC) allografts on clinical outcomes of allogeneic PBPC transplantation. We retrospectively analyzed transplanted doses of various immunocompetent cells from 27 HLA-identical sibling donors in relation to engraftment, incidence of graft-versus-host disease (GVHD), and survival. Significant variability was documented in both absolute numbers and relative proportions of CD34+, CD2+, CD3+, CD4(high)+, CD4+25+, CD8(high)+, CD19+, CD56+, and CD56+16+ cells contained in these allografts. Stepwise Cox regression analysis revealed that the CD56+ cell dose was significantly inversely correlated with the incidence of GVHD. Thus, there was a significantly higher incidence of grade II acute GVHD in patients receiving a lower CD56+16+ cell dose (hazard ratio (HR) 0.0090; 95% confidence interval (CI), <0.00001-3.38; P=0.031), a higher incidence of chronic GVHD in those receiving allografts with a lower CD56+16+ to CD34+ ratio (HR <0.00001; 95% CI <0.00001-0.0007; P=0.0035), and a higher incidence of extensive chronic GVHD in those receiving allografts with a lower CD56+ to CD34+ ratio (HR <0.00001; 95% CI <0.00001-0.053; P=0.0083). These results suggest that CD56+ cells in G-PBPC allografts from HLA-identical sibling donors may play an important role in preventing the development of GVHD.
1. The effects of substrate concentration and enzyme source (human liver microsomes and recombinant cytochrome P450s, CYP) on the activation of 7-benzyloxyresorufin O-debenzylation and nifedipine oxidation were investigated. 2. 7-Benzyloxyresorufin O-debenzylase activity in human liver microsomes was inhibited by a monoclonal antibody against CYP2B6 and a polyclonal antibody against CYP3A2 by 53-69 and 19-44%, respectively, suggesting that CYP2B6 and CYP3A4 mainly catalyse 7-benzyloxyresorufin O-debenzylation in human liver microsomes. 3. 7-Benzyloxyresorufin O-debenzylase activity at 0.2-5 micro M substrate concentrations in human liver microsomes was increased by the addition of alpha-naphthoflavone, quinidine, testosterone and progesterone, and the V(max) of 7-benzyloxyresorufin O-debenzylation increased with increasing alpha-naphthoflavone concentrations, whereas the K(m) remained constant. Additionally, 7-benzyloxyresorufin O-debenzylation by recombinant CYP3A4 was increased by the addition of alpha-naphthoflavone, testosterone and progesterone but not by quinidine, whereas no chemicals tested could activate the O-debenzylation of 7-benzyloxyresorufin by CYP2B6. 4. The K(m) for nifedipine oxidation activity by CYP3A4 decreased by the addition of progesterone, whereas the V(max) remained constant. Quinidine and testosterone increased 7-benzyloxyresorufin O-debenzylase and nifedipine oxidase activities, respectively, in human liver microsomes, whereas activation was not observed in CYP3A4. 5. The results suggest that in vitro activation patterns are substrate dependent and that selection of the enzyme source can influence the activation phenomenon.
Glutathione (GSH) participates in deoxidization and elimination of hydrogen peroxide and other reactive oxygen species, and plays an important part in the antioxidant system. To investigate the effect of GSH content on insulin gene expression, we utilized a stable transfectant, designated as ribo-MIN6 cells, which were stably transfected with the ribozyme of gamma-glutamylcysteine synthetase (gamma-GCS), exhibiting approximately 50% reduction of intracellular GSH content. We transiently transfected a luciferase expression vector driven by human preproinsulin gene promoter spanning from -1998 to +237 (pINS-1998/luc) and several deletion constructs into ribo-MIN6. Furthermore, transient transfection with ribozyme vector and pINS-1998/luc into wild-type MIN6 cells was also carried out. Luciferase activity was about 9-fold higher in ribo-MIN6 cells as compared to wild-type MIN6 cells. In the transient transfection of pINS-1998/luc with gamma-GCS ribozyme vector into wild-type MIN6 cells, the luciferase activity was increased in proportion to the added amounts of ribozyme vector. In transfection with deletion constructs, two major sites were found to be critical for insulin promoter activity. For the wild-type MIN6 cells, regions important for the promoter activity were also located at regions similar to those of ribo-MIN6 cells. Our results suggest that the suppression of intracellular GSH level might, in part, regulate the insulin gene expression.
Schizophrenic and normal control subjects were examined using both H-magnetic resonance spectroscopy (MRS) and structural MR imaging, in order to accurately assess the partial volume within the spectroscopic volume of interest (VOI) in the anterior cingulate cortex. The gray matter volume within VOI correlated positively with the N-acetyl-aspartate (NAA) to choline (Cho) ratio in schizophrenics only, not in controls. Schizophrenic patients had a reduced NAA/Cho ratio and an elevated Cho/creatine ratio compared to controls after the partial volume effect was eliminated. There was a significant negative correlation between the NAA/Cho ratio and the severity of blunted affect symptom in schizophrenics. These results provide further support to the idea that the measures of H-MRS indicate not only neuronal loss but also neuronal dysfunction in schizophrenia.
The present study was carried out to examine the contents of 18 minor and trace metals in five typical municipal waste ashes in Japan. In the waste ashes, Li, Ga, Rb, Y, Zr had relatively higher concentrations, approximately 5-300 mg kg(-1), the remaining metal concentrations were generally approximately 0.05-20 mg kg(-1). A comparison of the metal concentrations in the waste ashes and in Japanese agricultural soils indicated that the ratios for Ga, Mo, Ag, Sb, W, Bi between sewage sludge ash (SSA) and the soils were approximately 10-100 and for the remaining metals approximately 0.2-2; the ratios between food scrap ash (FSA), animal waste ash (AWA), horticulture waste ash (HWA) and incinerator bottom ash (IBA) and the soils were approximately 0.2-5. Furthermore, an overall evaluation on the waste ashes was also carried out using factor analysis with the addition of the other 21 elements examined in a companion paper. In the waste ashes, the major nutrient elements and heavy metals were mainly described by four factors: factors 1 and 2 explained the main information of the minor and trace metals while factors 3 and 4 explained that of the major nutrient elements. Factor 2 in the score plots could be used to evaluate the potential risk of the waste ashes to agricultural soils. Of the five types of waste ashes, SSA and IBA were abundant with minor and trace metals; AWA was relatively abundant with major nutrient elements especially for K; FSA was relatively abundant with major nutrient elements except for K, while HWA was not abundant with either of them.
The chemical characteristics of 89 municipal waste ashes, including food scrap ash (FSA), animal waste ash (AWA), horticulture waste ash (HWA), sewage sludge ash (SSA) and incinerator bottom ash (IBA), from various locations in Japan were examined with the aim of evaluating their suitability for use in agriculture. Although the waste ashes came from different sources and consisted of various materials, the gross elemental composition was similar. Acid neutralization capacity (liming effect) for the waste ashes was equivalent to 10-30% of CaO and followed the sequence SSA > IBA > AWA > FSA > HWA. Average P concentrations for the five types of waste ashes ranged from 10 to 29 g kg(-1) and average K concentrations ranged from 14 to 63 g kg(-1), respectively. Metal contents in the waste ashes were compared with levels in Japanese agricultural soils. K in the waste ashes was 1.3-6 times higher and Ca was 3-12 times higher; contents of the other metals in FSA, AWA and HWA were generally less than five times higher, but Ni, Cu, Zn, Cd, Sn, Pb in SSA or IBA were approximately 10-200 times higher than those in soils. Moreover, the ceiling amounts of waste ashes that may be applied to main Japanese agricultural soils were calculated by using soil contamination standards for Cu. Water solubility of P and metals in the waste ashes were also examined.
The distributions of radionuclides in plant components as to radionuclide transfer to animals are important for understanding the dynamics of radionuclides in an agricultural field. Most of the non-edible parts in these components are returned to the soil as organic fertilizer where they may again be utilized in the soil-plant pathway and/or are mixed with feed for livestock. Rice plants were grown in an experimental field and separated at harvest into different components, including polished rice, rice bran, hull, leaves, stem and root, and then the distributions of radioactive 137Cs, stable 133Cs and K in these components were determined. The distribution of 137Cs in polished rice and rice bran was similar to that of 133Cs, while that of K was different. The concentration ratios of 133Cs/K in leaf blade positions increased with aging, which means that the translocation rate of 133Cs in rice plants was slower than that of K. At harvest the distribution of dry weight in polished rice to entire rice plants was 34%, and the distributions of 133Cs in the polished rice and the non-edible parts were 7 and 93%, respectively, whereas those of K in the polished rice and the non-edible parts were 2 and 98%, respectively. Findings suggest that the transfer and distribution of 133Cs, not of K, provide better information on the long-term fate of 137Cs in an agricultural environment.