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Biomedical subjects

S Yamasaki

Publications and source records attributed to S Yamasaki.

At least 19 recordsLinked to original sources
PubMed2006

Konjak mosaic virus: the complete nucleotide sequence of the genomic RNA and its comparison with other potyviruses.

Konjak mosaic virus (KoMV) belongs to the genus Potyvirus, family Potyviridae. The complete nucleotide sequence of KoMV F isolate (KoMV F) was determined. The genome is 9,544 nucleotides long excluding the 3' terminal poly A tail and encodes a typical potyviral 350-kDa polyprotein of 3,087 amino acids. Phylogenetic analysis using known potyvirus polyproteins shows that KoMV constitutes a branch with yam mosaic virus, close to another branch including Japanese yam mosaic virus, turnip mosaic virus, scallion mosaic virus and lettuce mosaic virus. The 3' terminal 1,842 nucleotides of a different isolate of KoMV, K-2, was also determined, covering the C-terminal 292 amino acids of the nuclear inclusion protein b (NIb), coat protein (CP), and the 3' untranslated region. The amino acid sequences of the KoMV F CP and the nucleotide sequences of the KoMV F 3' untranslated region showed 92.5 and 90.5% identity to the corresponding genes of K-2, 88.7-96.8 and 92.7-94.4% to those of Zantedeschia mosaic virus (ZaMV) isolates, 87.5-89.7% and 85.5-90.3% to those of Japanese hornwort mosaic virus (JHMV) isolates. These results showed that KoMV is a distinct potyvirus and that KoMV, ZaMV, and JHMV are members of the same potyvirus species. Considering that KoMV was the first of these to be described, ZaMV and JHMV may be considered isolates of KoMV.

Amorphophallus↗
PubMed2006

Enterotoxigenicity of mature 45-kilodalton and processed 35-kilodalton forms of hemagglutinin protease purified from a cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain.

Cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain PL-21 is the etiologic agent of cholera-like syndrome. Hemagglutinin protease (HAP) is one of the major secretory proteins of PL-21. The mature 45-kDa and processed 35-kDa forms of HAP were purified in the presence and absence of EDTA from culture supernatants of PL-21. Enterotoxigenicities of both forms of HAP were tested in rabbit ileal loop (RIL), Ussing chamber, and tissue culture assays. The 35-kDa HAP showed hemorrhagic fluid response in a dose-dependent manner in the RIL assay. Histopathological examination of 20 microg of purified protease-treated rabbit ileum showed the presence of erythrocytes and neutrophils in the upper part of the villous lamina propria. Treatment with 40 microg of protease resulted in gross damage of the villous epithelium with inflammation, hemorrhage, and necrosis. The 35-kDa form of HAP, when added to the lumenal surface of rat ileum loaded in an Ussing chamber, showed a decrease in the intestinal short-circuit current and a cell rounding effect on HeLa cells. The mature 45-kDa form of HAP showed an increase in intestinal short-circuit current in an Ussing chamber and a cell distending effect on HeLa cells. These results show that HAP may play a role in the pathogenesis of PL-21.

Animals↗
PubMed2006

[Airway injuries due to blunt chest trauma].

Although the incidence of blunt chest trauma is very high, the mediastinal tracheobronchial injuries are quite rare. The airway injuries are thought to be one of the most urgent clinical conditions in thoracic surgery, and we are requested to make not only a rapid and sharp diagnosis but also an appropriate treatment plan considering combined injuries. We present 9 cases of tracheobronchial injuries due to blunt chest trauma in recent years. The average age of these patients is 26.1 years, and they are consisted of 6 male and 3 female. The cause of trauma is traffic accident in 7, and occupational crane accident in 2. Bronchoplasty were done in 5 cases (right main bronchus in 2, left main bronchus in 1, trunks intermediate bronchus in 1, and the spur between middle and lower lobe in 1), membranous-tracheoplasty with right pneumonectomy in 1, left pneumonectomy in 1, conservative treatment in 2. Postoperative mortality is occurred in 1 case who was suffering from multiple injuries including severe head injury and contralateral lung contusion. Tracheobronchial plasties should be chosen if possible to preserve lung function for the patient suffering from airway injuries.

Adolescent↗
PubMed2005

Er81 is expressed in a subpopulation of layer 5 neurons in rodent and primate neocortices.

Laminar organization is a fundamental cytoarchitecture in mammalian CNS and a striking feature of the neocortex. ER81, a transcription factor, has recently been utilized as a marker of cells in the layer 5 of the neocortex. We further pursued the distribution of ER81 to investigate the identity of the ER81-expressing cells in the brain. Er81 transcript was expressed in a subset of pyramidal cells that were scattered throughout the entire width of layer 5. In the rat cortex, Er81 transcripts were first detected in the ventricular zone at E15, remained expressed in putative prospective layer 5 neurons during infant and juvenile stages. The ER81-expressing subpopulation in adult layer 5 neurons did not segregate with the phenotypes of the projection targets. By retrograde labeling combined with immunohistochemistry or reverse transcription-polymerase chain reaction analysis, we found ER81 expression in nearly all of the layer 5 neurons projecting to the spinal cord or to the superior colliculus, while in only one-third of the layer 5 neurons projecting to the contralateral cortex. Er81 was also detected in layer 5 neurons in a P2 Japanese macaque monkey but not in adult monkey cortices. These findings suggest that a neuron class defined by a molecular criterion does not necessarily segregate with that defined by an anatomical criterion, that ER81 is involved in cell differentiation of a subset of layer 5 projection neurons and that this mechanism is conserved among rodents and primates.

Aging↗
PubMed2005

Dairy farm investigation on Shiga toxin-producing Escherichia coli (STEC) in Kolkata, India with emphasis on molecular characterization.

An investigation was conducted to determine the distribution, virulence gene profile and phenotypes of Shiga toxin-producing Escherichia coli (STEC) strains within a dairy farm in Kolkata, India by characterizing the STEC strains isolated from healthy dairy cow and calf stool samples, raw milk and farm floor swabs from July 2001 to March 2002. Primary screening by multiplex-PCR detected stx1 and stx2, the common virulence genes of STEC, in 18.9% of cow faeces, 32.4% of calf stool samples, 21.6% of farm floor swabs and 4.5% of raw milk samples and viable STEC were recovered from 4.5, 9.9, 8.1 and 1.8% of the corresponding PCR-positive samples. Strains harbouring stx1 (63.3%) and hlyA (53.3%) were frequently detected compared to eae (13.3%). Most of the strains harboured similar sets of reported virulence genes common among isolates from diarrhoea patients. Most of the strains also exhibited multidrug resistance, sorbitol fermentation and produced enterohaemolysin. The randomly amplified polymorphic DNA-PCR (RAPD-PCR) profile of the STEC strains isolated from the farm milieu revealed diverse banding patterns and clonal analysis demonstrated that the strains from different sources were not identical but showed some genetic relatedness. The study demonstrates the potential of dairy farm for housing virulent STEC.

Animals↗
PubMed2005

Efficient engraftment of primary adult T-cell leukemia cells in newborn NOD/SCID/beta2-microglobulin(null) mice.

Adult T-cell leukemia (ATL) develops via multiple oncogenic steps in human T-cell leukemia virus type I (HTLV-I) carriers. To better understand pathogenesis of ATL, we developed a novel xenogeneic engraftment model in which primary ATL cells are intravenously transplanted into neonatal nonobese diabetic (NOD)/severe-combined immunodeficiency (SCID)/beta2-microglobulin(null) (NOD/SCID/beta2m(null)) mice. Acute-type ATL cells engrafted in the peripheral blood and in the lymph nodes of recipients at a high efficiency. Engrafted ATL cells were dually positive for human CD4 and CD25, and displayed patterns of HTLV-I integration identical to those of donors by Southern blot analysis. These cells infiltrated into recipients' liver, and formed nodular lesions, recapitulating the clinical feature of each patient. In contrast, in smoldering-type ATL cases, multiple clones of ATL cells engrafted efficiently in NOD/SCID/beta2m(null) mice. When smoldering-type ATL cells were retransplanted into secondary NOD/SCID/beta2m(null) recipients, single HTLV-I-infected clones became predominant, suggesting that clones with dominant proliferative activity can be competitively selected in this xenogeneic system. Taken together, the NOD/SCID/beta2m(null) newborn system is useful to understand kinetics, metastasis, and disease progression of ATL in vivo.

Anemia, Refractory, with Excess of Blasts↗
PubMed2004

In situ ESR observation of interface dangling bond formation processes during ultrathin SiO2 growth on Si(111).

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.

Journal Article↗
PubMed2004

Cytokines regulate fibroblast-like synovial cell differentiation to adipocyte-like cells.

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.

Adipocytes↗
PubMed2004

Genotypes and phenotypes of Shiga toxin producing-Escherichia coli isolated from healthy cattle in Thailand.

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.

Animals↗
PubMed2004

Allogeneic peripheral blood stem cell transplantation from two- or three-loci-mismatched related donors in adult Japanese patients with high-risk hematologic malignancies.

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.

Adolescent↗
PubMed2004

Prevalence, serotype distribution, antibiotic susceptibility and genetic profiles of mesophilic Aeromonas species isolated from hospitalized diarrhoeal cases in Kolkata, India.

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.

Aeromonas↗
PubMed2004

Osteoprotegerin (OPG) acts as an endogenous decoy receptor in tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis of fibroblast-like synovial cells.

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.

Antibodies, Monoclonal↗
PubMed2004

Anti-apoptogenic function of TGFbeta1 for human synovial cells: TGFbeta1 protects cultured synovial cells from mitochondrial perturbation induced by several apoptogenic stimuli.

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.

Apoptosis↗
PubMed2004

Diabetes mellitus decreases hippocampal release of neurotransmitters: an in vivo microdialysis study of awake, freely moving rats.

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.

Animals↗