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Biomedical subjects

K Tamura

Publications and source records attributed to K Tamura.

At least 19 recordsLinked to original sources
PubMed2006

A perennial ryegrass CBF gene cluster is located in a region predicted by conserved synteny between Poaceae species.

CBF/DREB1 proteins are the most important regulators of the cold temperature signaling pathway in many plants. CBF genes are candidates for low-temperature tolerance QTL in wheat and barley. Ten novel putative CBF cDNAs of perennial ryegrass (Lolium perenne L.) have been isolated from cold-treated leaf tissue. Their primary structures contain some conserved motifs, characteristic of the gene class. Phylogenetic analysis revealed that LpCBF genes were attributable to the HvCBF3-, and HvCBF4-subgroups following the previously proposed classification of barley CBF genes. RT-PCR analysis revealed that the expression of LpCBF genes was rapidly induced in response to low temperature and that the expression pattern under the low-temperature conditions for a long period was different between the various LpCBF genes. Five of the ten LpCBF genes were assigned to the genetic linkage map using the p150/112 reference mapping population. LpCBFIb, LpCBFII, LpCBFIIIb and LpCBFIIIc were mapped on LG5 forming a cluster within 2.2 cM, while LpCBFVb was located on LG1. Based on comparative genetic studies, conserved synteny for CBF gene family was observed between the Triticeae cereals and perennial ryegrass. Information on the perennial ryegrass CBF genes at both the molecular and genetic level obtained in this study would be useful for the further study on the role of CBF genes and low-temperature tolerance in grasses.

Amino Acid Sequence↗
PubMed2006

FK330, a novel inducible nitric oxide synthase inhibitor, prevents ischemia and reperfusion injury in rat liver transplantation.

Nitric oxide (NO), produced via inducible NO synthase (iNOS), is implicated in the pathophysiology of liver ischemia/reperfusion injury (IRI). We examined the effects of a novel iNOS inhibitor, FK330 (FR260330), in well-defined rat liver IRI models. In a model of liver cold ischemia followed by ex vivo reperfusion, treatment with FK330 improved portal venous flow, increased bile production and decreased hepatocellular damage. FK330 prevented IRI in rat model of 40-h cold ischemia followed by syngeneic orthotopic liver transplantation (OLT), as evidenced by: (1) increased OLT survival (from 20% to 80%); (2) decreased hepatocellular damage (serum glutamic oxaloacetic transaminase/glutamic pyruvic transaminase levels); (3) improved histological features of IRI; (4) reduced intrahepatic leukocyte infiltration, as evidenced by decreased expression of P-selectin/intracellular adhesion molecule 1, ED-1/CD3 cells and neutrophils; (5) depressed lymphocyte activation, as evidenced by expression of pro-inflammatory cytokine (TNF-alpha, IL-1beta, IL-6) and chemokine (IP-10, MCP-1, MIP-2) programs; (6) prevented hepatic apoptosis and down-regulated Bax/Bcl-2 ratio. Thus, by modulating leukocyte trafficking and cell activation patterns, treatment of rats with FK330, a specific iNOS inhibitor, prevented liver IRI. These results provide the rationale for novel therapeutic approaches to maximize organ donor pool through the safer use of liver grafts despite prolonged periods of cold ischemia.

Animals↗
PubMed2006

Interacting molecule of AT1 receptor, ATRAP, is colocalized with AT1 receptor in the mouse renal tubules.

The renin-angiotensin system in the kidney plays a critical role in the regulation of renal hemodynamics and sodium handling through the activation of vascular, glomerular and tubular angiotensin II type 1 (AT1) receptor-mediated signaling. We previously cloned a molecule that specifically bound to the AT1 receptor and modulated AT1 receptor signaling in vitro, which we named ATRAP (for AT1 receptor-associated protein). The purpose of this study is to analyze the renal distribution of ATRAP and to examine whether ATRAP is co-expressed with the AT1 receptor in the mouse kidney. We performed in situ hybridization, Western blot analysis, and immunohistochemistry to investigate the expression of ATRAP mRNA and protein in the mouse kidney. The results of Western blot analysis revealed the ATRAP protein to be abundantly expressed in the kidney. Employing in situ hybridization and immunohistochemistry, we found that both ATRAP mRNA and the protein were widely distributed along the renal tubules from Bowman's capsules to the inner medullary collecting ducts. ATRAP mRNA was also detected in the glomeruli, vasculature, and interstitial cells. In all tubular cells, the ATRAP protein colocalized with the AT1 receptor. Finally, we found that the dietary salt depletion significantly decreased the renal expression of ATRAP as well as AT1 receptor. These findings show ATRAP to be abundantly and broadly distributed in nephron segments where the AT1 receptor is expressed. Furthermore, this is the first report demonstrating a substantial colocalization of ATRAP and AT1 receptor in vivo.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Successful induction of immune tolerance by continuous infusion of recombinant factor VIII in a haemophilia A patient with high-inhibitor titres.

The successful and persistent abolition of the inhibitor is of significant clinical benefit, as it allows for the restoration of the usual treatment with clotting factor concentrate. We describe a successful induction of immune tolerance by continuous infusion of recombinant factor VIII (rFVIII) in a 5-year-old boy with severe haemophilia A and high-responding inhibitor. He had previously been subjected to immune tolerance induction (ITI) with rFVIII at 100 units (U) kg(-1) three times weekly. One year after the beginning of therapy tolerance was not achieved and a high titer of inhibitor was detected (15 Bethesda Units). The patient had a sudden onset of severe neck pain. The diagnosis of spinal epidural haematoma was revealed by magnetic resonance imaging, and emergency laminectomy with evacuation of the haematoma was required. The patient received sequential therapy for surgery first as bolus rFVIII injection of 500 U kg(-1) in order to overwhelm the inhibitor and then as continuous infusion at 6 to 12 U kg(-1) hour(-1) to avoid bleeding episodes in the postoperative period. After the 3 weeks of continuous infusion, the inhibitor became undetectable. Thereafter, prophylactic treatment with rFVIII was started three times weekly, and the inhibitor has remained undetectable for 6 months. The, present case suggests that continuous infusion of rFVIII may be an effective therapy to induce immune tolerance.

Child, Preschool↗
PubMed2006

A synergistic effect between PG490-88 and tacrolimus prolongs renal allograft survival in monkeys.

This study was undertaken to determine if PG490-88 and tacrolimus (Tac) act synergistically to prevent renal allograft rejection in monkeys and to explore possible mechanisms of synergy between these agents. MHC-mismatched renal allografts were transplanted into cynomolgus monkeys after bilateral nephrectomy. Recipients were divided into the following groups: (i) no treatment; (ii) PG490-88 (0.03 mg/kg); (iii) Tac (1 mg/kg); (iv) PG490-88 (0.01 mg/kg) + Tac (1 mg/kg) and (v) PG490-88 (0.03 mg/kg) + Tac (1 mg/kg). Through synergy PG490-88 and Tac inhibited anti-CD3/PMA-induced T-cell proliferation and IFN-gamma expression in vitro. Tac monotherapy only marginally prolonged survival (27 +/- 3.2 days), while the combination of PG490-88 and Tac significantly prolonged graft survival to a median of 99 days (PG490-88 at 0.03 mg) and 38.5 days (PG490-88 at 0.01 mg/kg). Prolonged survival correlated with inhibited IgM production as well as reduced T-cell infiltration, IL-2 protein expression and NF-AT/NF-kappaB activity. We conclude that PG490-88 and a subtherapeutic dose of Tac significantly prolong renal allograft survival in monkeys through the synergistic inhibition of T-cell activation and a decrease in IFN-gamma production and NF-AT/NF-kappaB activity.

Animals↗
PubMed2006

[Surgical technique of aortic valve replacement for small aortic annulus in elderly patients].

Recent reports have shown that aortic valve replacement in elderly patients over 65 years with atherosclerotic aortic stenosis and a small aortic annulus is possible by using a small sized bioprosthesis (Carpentier-Edwards pericardial valve). Here we present out surgical technique. Firstly, the native calcified aortic valve was removed completely to gain total exposure of the surrounding aortic root and sinus of Valsalva like Bentall procedure. Secondly, a small sized bioprosthesis was implanted with intermittent noneverting mattress 2-0 sutures with spaghetti and small polytetrafluoroethylene (PTFE) felt. Aortic annulus is the dilated by inserting Hegar dilator sizing from 25 to 27 mm. Therefore, aortic valve replacement for small aortic annulus in intra- or supra-annular position should be easily accomplished. Good surgical results and hemodynamic state were achieved in 25 consecutive cases using this technique.

Aged↗
PubMed2006

[Aortic regurgitation caused by rupture of a fibrous strand; report of a case].

Rupture of a fibrous strand of a tricuspid aortic valve is extremely rare. We describe a patient with aortic regurgitation due to spontaneous rupture of the fibrous strands that suspend the aortic valve leaflets. The fibrous strands were recognized between the left and right coronary cusps, and between the left coronary and non-coronary cusps during the operation. The fibrous strand between the left coronary and non-coronary cusps had been ruptured, and thus the left coronary and non-coronary cusps were prolapsed into the left ventricle. Since a degenerative change was observed histologically in the resected specimen, these fibrous strands were considered to be an embryonic remnant of the aortic valve.

Aged↗
PubMed2005

Development of the polymerase chain reaction assay based on the canine genome database for detection of monoclonality in B cell lymphoma.

From the canine genome database and its bioinformatic analysis, we identified conserved sequences within the vast majority of 61 variable segments and 1 joining segment of the immunoglobulin heavy chain (IgH) gene, and designed optimal primers for polymerase chain reaction (PCR) amplification directed at these conserved sequences to evaluate the monoclonality of IgH in canine B cell lymphoma. Using the primers, a PCR-based assay was performed on fine-needle aspiration samples of normal, hyperplasia, and malignant lymph nodes and lymphoma cell lines. All fine-needle aspiration samples of five B cell lymphoma cases and the B cell lymphoma line GL-1 exhibited clonal amplification, whereas no amplification was observed in the samples from normal and hyperplasia lymph nodes, cases of T cell lymphoma, and the T cell lymphoma line CL-1. The primers we designed clearly distinguished malignant B lymphocytes from normal, reactive, and malignant T lymphocytes, indicating a potential utility of the primers for PCR-based routine clinical examination for canine B cell lymphoma.

Animals↗
PubMed2005

Buckling of spherical shells adhering onto a rigid substrate.

Deformation of a spherical shell adhering onto a rigid substrate due to van der Waals attractive interaction is investigated by means of numerical minimization (conjugate gradient method) of the sum of the elastic and adhesion energies. The conformation of the deformed shell is governed by two dimensionless parameters, i.e., Cs/epsilon and Cb/epsilon where Cs and Cb are respectively the stretching and the bending constants, and epsilon is the depth of the van der Waals potential between the shell and substrate. Four different regimes of deformation are characterized as these parameters are systematically varied: (i) small deformation regime, (ii) disk formation regime, (iii) isotropic buckling regime, and (iv) anisotropic buckling regime. By measuring the various quantities of the deformed shells, we find that both discontinuous and continuous bucking transitions occur for large and small Cs/epsilon, respectively. This behavior of the buckling transition is analogous to van der Waals liquids or gels, and we have numerically determined the associated critical point. Scaling arguments are employed to explain the adhesion induced buckling transition, i.e., from the disk formation regime to the isotropic buckling regime. We show that the buckling transition takes place when the indentation length exceeds the effective shell thickness which is determined from the elastic constants. This prediction is in good agreement with our numerical results. Moreover, the ratio between the indentation length and its thickness at the transition point provides a constant number (2-3) independent of the shell size. This universal number is observed in various experimental systems ranging from nanoscale to macroscale. In particular, our results agree well with the recent compression experiment using microcapsules.

Journal Article↗
PubMed2005

Facial emphysema caused by cheek bite.

Biting of the buccal mucosa is very frequent injury, whereas facial emphysema caused by cheek bite is rare. We report a case of facial emphysema causing puffing of the cheek through a self-inflicted bite of the buccal mucosa.

Bites, Human↗
PubMed2005

Identification and gene expression of bovine C-type lectin dectin-2.

The C-type lectin receptor has been shown to recognize carbohydrate moieties of self and non-self antigens, thus serving as an innate immune receptor. Using bioinformatics and molecular cloning techniques, we isolated a bovine gene that encodes a polypeptide of 206 amino acids with structural features shared by mouse and human dectin-2, including a high homology with mouse dectin-2 (66%), a type II configuration, a short cytoplasmic domain without tyrosine-based signal motifs, a carbohydrate recognition domain, a putative N-glycosylation site, and an EPN motif involved in the Ca(2+)-dependent binding of hexose carbohydrates. These results reveal this bovine gene to be a counterpart of mouse dectin-2. Moreover, the bovine dectin-2 gene showed heterogeneity in mRNA (the generation of alternatively spliced transcript) and segmentation into six exons, which are also observed in mouse dectin-2. Inconsistent with mouse dectin-2 mRNA, the bovine counterpart is abundantly expressed by Langerhans cells compared to macrophages; however, lymph nodes showed the highest expression level of bovine dectin-2, while spleen and lung showed the highest expression levels of mouse and human dectin-2. In cattle, dectin-2 expressed by dendritic cells may be clinically involved in the recognition of invading antigens in lymph nodes.

Amino Acid Sequence↗
PubMed2005

Characterization of cDNA and the genomic sequence encoding canine neural-cell adhesion molecule, CD56/N-CAM.

The neural-cell adhesion molecule, CD56/N-CAM is a member of the immunoglobulin superfamily expressed by various tissues and cells, including natural killer (NK) cells. Despite the importance of CD56 as a marker for identifying NK cells in circulating blood, canine CD56 has not been identified. In the present study, we identified the canine counterparts of the 140-kDa (CD56-140) and 120-kDa (CD56-120) isoforms of human DC56. Both of amino acid sequences encoded by the canine CD56-140 and -120 cDNA showed high homology with those of human (both 96% homology), having well-conserved domains (five immunoglobulin, two fibronectin type III, and transmembrane and intracellular or glycosylphosphatidylinositol-linked domain) among various species (human, mouse, and feline). We revealed that the transcripts of canine CD56-140 and -120 arise from alternative mRNA splicing from a single gene located on canine chromosome 5. Moreover, the mRNA encoding canine CD56-140 was expressed at high levels constitutively by nervous system and endocrine tissues as has shown in other animals.

Alternative Splicing↗
PubMed2005

The biological effects of high-pressure gas on the yeast transcriptome.

The aim of the present study was to examine the feasibility of DNA microarray technology in an attempt to construct an evaluation system for determining gas toxicity using high-pressure conditions, as it is well known that pressure increases the concentration of a gas. As a first step, we used yeast (Saccharomyces cerevisiae) as the indicator organism and analyzed the mRNA expression profiles after exposure of yeast cells to nitrogen gas. Nitrogen gas was selected as a negative control since this gas has low toxicity. Yeast DNA microarray analysis revealed induction of genes whose products were localized to the membranes, and of genes that are involved in or contribute to energy production. Furthermore, we found that nitrogen gas significantly affected the transport system in the cells. Interestingly, nitrogen gas also resulted in induction of cold-shock responsive genes. These results suggest the possibility of applying yeast DNA microarray to gas bioassays up to 40 MPa. We therefore think that "bioassays" are ideal for use in environmental control and protection studies.

Feasibility Studies↗
PubMed2005

Protective effects of PG490-88 on chronic allograft rejection by changing intragraft gene expression profiles.

Our previous study showed that PG490-88 effectively ameliorated both functional and histological changes of chronic rejection in the rat. In this experiment, we investigated the intragraft gene expression profiles of PG490-88 under successful prevention of chronic rejection in rat kidney allografts. Kidneys of F344 rats were transplanted into bilaterally nephrectomized LEW recipients. Recipients with a brief course of low-dose FK506 (1 mg/kg per day for 10 days) were dosed with PG490-88 0.5 mg/kg per day, which was predetermined and defined as the effective dose of preventing chronic allograft rejection in this model, for 90 days after grafting. Kidney grafts were harvested on day 90 after transplantation and subjected to gene expression analysis by real-time RT-PCR. Overall, the expression levels of all genes tested were upregulated in the brief course of low-dose FK506 control. PG490-88 treatment exhibited significant inhibition of intragraft m RNA levels of iNOS, IL-6, and perforin and marginal downregulation of IL-2, IFNgamma, IRF-1, TNFalpha, and TGFbeta. There was no change in IL-10, granzyme B, and PDGFalpha, when compared to the brief course of low-dose FK506 control. These results suggested that downregulation of multiple intragraft gene expression by mainly suppression of iNOS, IL-6, and perforin might be responsible for successful prevention of chronic kidney allograft nephropathy by PG490-88 in rats.

Animals↗
PubMed2005

Isolation and transplantation of highly purified autologous peripheral CD34+ progenitor cells: purging efficacy, hematopoietic reconstitution in non-Hodgkin's lymphoma (NHL): results of Japanese phase II study.

The purging efficacy of positive selection of autologous CD34+ PBSC with a clinical scale method of magnetic-activated cell sorting system (CliniMACS) was investigated in 48 patients with non-Hodgkin's lymphoma (NHL). The median purity and recovery rate of the CD34+ cells post-selection were 93.3% (range 32.6-99.3) and 72.2% (range 20.5-309.8), respectively. The real-time PCR method to detect the patient-specific monoclonal immunoglobulin heavy chain gene rearrangement (minimal residual tumor; MRT) and CD19 and CD20 positivities were used for the detection of contaminating NHL cells before and after CD34+ selection. After selection, the median (range) depletion rate of MRT was 2.53 (1.52-4.78) log, and that of CD19+ cell and CD20+ cell was 2.46 (0.74-3.64) log and 2.32 (0.40-4.01) log, respectively. In 41 patients, high-dose chemotherapy was performed, followed by the transplantation of the isolated CD34+ cells. Rapid neutrophil recovery as well as platelet recovery was seen with a median time to reach 0.5 x 10(9)/l neutrophils of 10 days (range 8-13) and 20 x 10(9)/l platelets of 14 days (range 10-34), respectively. The present study demonstrated that CliniMACS is a highly effective positive selection method and a high purging efficacy could be obtained without compromising the hematopoietic reconstitution capacity of the graft in NHL patients undergoing high-dose chemotherapy.

Adult↗
PubMed2005

Association between IL-18 gene promoter polymorphisms and inflammatory bowel disease in a Japanese population.

BACKGROUND: Interleukin-18 (IL-18) is a pleiotropic cytokine that induces the production of interferon (IFN)-gamma and also to regulate Th2 cytokines. Recently, association studies between IL-18 gene promoter polymorphisms and several Th1- or Th2-mediated inflammatory diseases were reported. In inflammatory bowel diseases (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), recent evidence suggests that IL-18 is involved in the pathogenesis. METHODS: Using DNA direct sequencing, we investigated IL-18 gene promoter polymorphisms at -607C/A and -137G/C. Allele, genotype, and haplotype frequencies were determined in 210 Japanese patients with UC, 205 patients with CD, and 212 controls. RESULTS: In UC, the -137C allele frequency was significantly higher in the proctitis-type patients than in controls (Pc = 0.0068). The -137 genotype frequency was also significantly different in the proctitis-type patients than in controls (Pc = 0.032). No other allele and genotype frequencies were significantly associated with UC after Bonferroni correction. Furthermore, the frequency of haplotype 2 (-607A, -137C), which had a lower promoter activity and IFN-gamma mRNA level than the other haplotypes as previously reported, was significantly higher in the proctitis-type patients than in controls (Pc = 0.01). In CD, we could not find any significant differences. CONCLUSIONS: IL-18 gene promoter polymorphisms may not be associated with disease susceptibility but related to the extent of disease in UC.

Adolescent↗
PubMed2005

Effect of incadronate on proliferation of mesenchymal tumor cells with or without activated Ras mutation.

The present investigation examined the effect of bisphosphonates on six mesenchymal tumor cell lines and the mechanisms of inhibition of tumor cell proliferation. HT-1080, a fibrosarcoma cell line that exhibits increased Ras activity due to a mutation of the Ras gene, demonstrated significantly reduced tumor cell proliferation upon treatment with incadronate. The other cell lines, however, which lack mutation of the Ras gene, showed no influence upon treatment with incadronate. Autoradiography demonstrated no difference in the uptake of 3H-labelled incadronate between susceptible and unaffected cells. The anti-proliferation of HT-1080 was reversed by the addition of geranylgeranyl pyrophosphate. Etidronate exhibited no influence on all tested cell lines. On the basis of these data, we hypothesized that incadronate inhibits the mevalonate pathway and blocks oncogenic Ras signaling. In an effort to confirm this hypothesis, the influence of incadronate on an oncogenic Ras transfected BALB/3T3 cell line (Bhas 42) and a parental BALB/3T3 cell line were compared. The parental BALB/3T3 cells showed slight inhibition upon treatment with incadronate, however, the proliferation of Bhas 42 cells was significantly reduced. These results suggest that incadronate suppresses oncogenic Ras-activated mesenchymal tumors through the inhibition of Ras signaling pathways.

Animals↗