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Search Results: 1 - 10 of 2188 matches for " Takuji Sasaki "
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Asymmetric Distribution of Gene Expression in the Centromeric Region of Rice Chromosome 5
Hiroshi Ikawa,Takuji Sasaki,Takashi Matsumoto
Frontiers in Plant Science , 2011, DOI: 10.3389/fpls.2011.00016
Abstract: There is controversy as to whether gene expression is silenced in the functional centromere. The complete genomic sequences of the centromeric regions in higher eukaryotes have not been fully elucidated, because the presence of highly repetitive sequences complicates many aspects of genomic sequencing. We performed resequencing, assembly, and sequence finishing of two P1-derived artificial chromosome clones in the centromeric region of rice (Oryza sativa L.) chromosome 5 (Cen5). The pericentromeric region, where meiotic recombination is silenced, is located at the center of chromosome 5 and is 2.14 Mb long; a total of six restriction-fragment-length polymorphism markers (R448, C1388, S20487S, E3103S, C53260S, and R2059) genetically mapped at 54.6 cM were located in this region. In the pericentromeric region, 28 genes were annotated on the short arm and 45 genes on the long arm. To quantify all transcripts in this region, we performed massive parallel sequencing of mRNA. Transcriptional density (total length of transcribed region/length of the genomic region) and expression level (number of uniquely mapped reads/length of transcribed region) were calculated on the basis of the mapped reads on the rice genome. Transcriptional density and expression level were significantly lower in Cen5 than in the average of the other chromosomal regions. Moreover, transcriptional density in Cen5 was significantly lower on the short arm than on the long arm; the distribution of transcriptional density was asymmetric. The genomic sequence of Cen5 has been integrated into the most updated reference rice genome sequence constructed by the International Rice Genome Sequencing Project.
The Best Choice to Achieve Zero Complications after Pancreatoduodenectomy  [PDF]
Shinji Osada, Hisashi Imai, Yoshiyuki Sasaki, Itaru Yasufuku, Ryuichi Asai, Yoshihisa Tokumaru, Takuji Sakuratani, Kazuhiro Yoshida
Surgical Science (SS) , 2011, DOI: 10.4236/ss.2011.22010
Abstract: Pancreatoduodenectomy (PD) has been performed commonly, but the occurrence of pancreatic fistula (PF) is a critical trigger of complications, which are potentially life threatening, and is also associated with markedly prolonged hospitalization. Many techniques have been proposed for connecting the pancreatic stump with the gastrointestinal tract, stomach vs. jejunum, etc. Among the risk factors for PF, such as general patient factors or disease-related factors, the most important is the texture of the remnant pancreas. Surgical technique might be one improvable aspect that can reduce the pancreatic leakage rate, therefore; various methods of managing the pancreatic remnant have been studied. Methods of reconstruction between the remnant pancreas and the intestine include end-to-side with/without duct-to-mucosa anastomosis or end-to-end invagination styles, has been argued. Here, we review several trials for safety and methods of treating the pancreatic stump after PD, and demonstrate our experiences.
Cryoablation-Induced Anti-Cancer Immune Reaction—Immune Reaction Induced By Cryoablation  [PDF]
Shinji Osada, Hisashi Imai, Yoshiyuki Sasaki, Kazuhiro Yoshida, Itaru Yasufuku, Ryuichi Asai, Yoshihisa Tokumaru, Takuji Sakuratani
Journal of Cancer Therapy (JCT) , 2011, DOI: 10.4236/jct.2011.22015
Abstract: Among the ablation procedures used against advanced liver cancer, thermal ablation therapy is widely applied, and the safety and efficacy of this technique have been well characterized. In contrast, the principle of cryosurgery is not only to control local recurrence, but also to stimulate the immune system into initiating an anti-tumor response. In recent years, we have developed a treatment method for patients with advanced liver tumors. From these experiences, repeated treatment was demonstrated to induce anti-cancer immune reaction-related factors. In the present review, mechanisms for anti-tumor immune reaction will be argued with introducing a novel strategy of a cryoablation.
Development in Rice Genome Research Based on Accurate Genome Sequence
Takashi Matsumoto,Jianzhong Wu,Baltazar A. Antonio,Takuji Sasaki
International Journal of Plant Genomics , 2008, DOI: 10.1155/2008/348621
Abstract: Rice is one of the most important crops in the world. Although genetic improvement is a key technology for the acceleration of rice breeding, a lack of genome information had restricted efforts in molecular-based breeding until the completion of the high-quality rice genome sequence, which opened new opportunities for research in various areas of genomics. The syntenic relationship of the rice genome to other cereal genomes makes the rice genome invaluable for understanding how cereal genomes function. Producing an accurate genome sequence is not an easy task, and it is becoming more important as sequence deviations among, and even within, species highlight functional or evolutionary implications for comparative genomics.
Development of an Inflammation-Associated Colorectal Cancer Model and Its Application for Research on Carcinogenesis and Chemoprevention
Takuji Tanaka
International Journal of Inflammation , 2012, DOI: 10.1155/2012/658786
Abstract: Chronic inflammation is a well-recognized risk factor for development of human cancer in several tissues, including large bowel. Inflammatory bowel disease, including ulcerative colitis and Crohn’s disease, is a longstanding inflammatory disease of intestine with increased risk for colorectal cancer development. Several molecular events involved in chronic inflammatory process may contribute to multistep carcinogenesis of human colorectal cancer in the inflamed colon. They include overproduction of reactive oxygen and nitrogen species, overproduction and upregulation of productions and enzymes of arachidonic acid biosynthesis pathway and cytokines, and intestinal immune system dysfunction. In this paper, I will describe several methods to induce colorectal neoplasm in the inflamed colon. First, I will introduce a protocol of a novel inflammation-associated colon carcinogenesis in mice. In addition, powerful tumor-promotion/progression activity of dextran sodium sulfate in the large bowel of mice will be described. Finally, chemoprevention of inflammation-associated colon carcinogenesis will be mentioned. 1. Introduction Relationship between inflammation and cancer has been suggested for a long time [1]. Since Marshall and Warren [2], who discovered Helicobacter pylori and reported its infection closely associated with gastric cancer development, won the Nobel Prize in Physiology or Medicine in 2005, there have been an increasing number of reports on PubMed as to the relationship between inflammation and carcinogenesis in a variety of tissues (Table 1) and it has been featured in major journals. Table 1: Inflammation and cancer in various tissues. In terms of the large bowel, it has been found that the risk of colorectal cancer increases in relation to the degrees of inflammation and the disease duration (duration/risk = 10 years/1.6%, 20 years/8.3%, and 30 years/18.4%) in inflammatory bowl diseases (IBDs) such as ulcerative colitis (UC) and Crohn’s disease (CD) (Figure 1) [3]. I have been interested in inflammation-associated colorectal carcinogenesis for a long time, since even younger patients with UC have high risk of colorectal cancer [4]. Figure 1: UC patients are high-risk groups of colorectal cancer (CRC) development. Patients with UC as well as those with colorectal cancer have been increasing in Asian countries including Japan, similarly to Western countries (Figure 2) [5]. Therefore, it is necessary to investigate the mechanisms of colorectal cancer development with the background of inflammation for establishing the countermeasure strategy
Preclinical Cancer Chemoprevention Studies Using Animal Model of Inflammation-Associated Colorectal Carcinogenesis
Takuji Tanaka
Cancers , 2012, DOI: 10.3390/cancers4030673
Abstract: Inflammation is involved in all stages of carcinogenesis. Inflammatory bowel disease, such as ulcerative colitis and Crohn’s disease is a longstanding inflammatory disease of intestine with increased risk for colorectal cancer (CRC). Several molecular events involved in chronic inflammatory process are reported to contribute to multi-step carcinogenesis of CRC in the inflamed colon. They include over-production of free radicals, reactive oxygen and nitrogen species, up-regulation of inflammatory enzymes in arachidonic acid biosynthesis pathway, up-regulation of certain cytokines, and intestinal immune system dysfunction. In this article, firstly I briefly introduce our experimental animal models where colorectal neoplasms rapidly develop in the inflamed colorectum. Secondary, data on preclinical cancer chemoprevention studies of inflammation-associated colon carcinogenesis by morin, bezafibrate, and valproic acid, using this novel inflammation-related colorectal carcinogenesis model is described.
Message Routing Algorithm with Additional Node-Information for Capability-Aware Object Management in P2P Networks
Takuji Tachibana
Lecture Notes in Engineering and Computer Science , 2008,
Colorectal carcinogenesis: Review of human and experimental animal studies
Tanaka Takuji
Journal of Carcinogenesis , 2009,
Abstract: This review gives a comprehensive overview of cancer development and links it to the current understanding of tumorigenesis and malignant progression in colorectal cancer. The focus is on human and murine colorectal carcinogenesis and the histogenesis of this malignant disorder. A summary of a model of colitis-associated colon tumorigenesis (an AOM/DSS model) will also be presented. The earliest phases of colorectal oncogenesis occur in the normal mucosa, with a disorder of cell replication. The large majority of colorectal malignancies develop from an adenomatous polyp (adenoma). These can be defined as well-demarcated masses of epithelial dysplasia, with uncontrolled crypt cell proliferation. When neoplastic cells pass through the muscularis mucosa and infiltrate the submucosa, they are malignant. Carcinomas usually originate from pre-existing adenomas, but this does not imply that all polyps undergo malignant changes and does not exclude de novo oncogenesis. Besides adenomas, there are other types of pre-neoplasia, which include hyperplastic polyps, serrated adenomas, flat adenomas and dysplasia that occurs in the inflamed colon in associated with inflammatory bowel disease. Colorectal neoplasms cover a wide range of pre-malignant and malignant lesions, many of which can easily be removed during endoscopy if they are small. Colorectal neoplasms and/or pre-neoplasms can be prevented by interfering with the various steps of oncogenesis, which begins with uncontrolled epithelial cell replication, continues with the formation of adenomas and eventually evolves into malignancy. The knowledge described herein will help to reduce and prevent this malignancy, which is one of the most frequent neoplasms in some Western and developed countries.
Possibility of Unconventional Pairing Due to Coulomb Interaction in Fe-Based Pnictide Superconductors: Perturbative Analysis of Multi-Band Hubbard Models
Takuji Nomura
Physics , 2008, DOI: 10.1143/JPSJS.77SC.123
Abstract: Possibility of unconventional pairing due to Coulomb interaction in iron-pnictide superconductors is studied by applying a perturbative approach to realistic 2- and 5-band Hubbard models. The linearized Eliashberg equation is solved by expanding the effective pairing interaction perturbatively up to third order in the on-site Coulomb integrals. The numerical results for the 5-band model suggest that the eigenvalues of the Eliashberg equation are sufficiently large to explain the actual high Tc for realistic values of Coulomb interaction and the most probable pairing state is spin-singlet s-wave without any nodes just on the Fermi surfaces, although the superconducting order parameter changes its sign between the small Fermi pockets. On the other hand the 2-band model is quite insufficient to explain the actual high Tc.
Perturbation Theory of High-Tc Superconductivity in Iron Pnictides
Takuji Nomura
Physics , 2008, DOI: 10.1143/JPSJ.78.034716
Abstract: The high-transition-temperature (high-Tc) superconductivity discovered recently in iron pnictides is analyzed within a perturbation theory. Specifically, the probable pairing symmetry, the doping dependence of the transition temperature and the pairing mechanism are studied by solving the Eliashberg equation for multi-band (2- and 5-band) Hubbard models with realistic electronic structures. The effective pairing interaction is expanded perturbatively in the on-site Coulomb integrals up to third order. Our perturbative weak-coupling approach shows that sufficiently large eigenvalues of the Eliashberg equation are obtained to explain the actual high transition temperatures by taking realistic on-site Coulomb integrals in the 5-band model. Thus, unconventional (non-phonon-mediated) superconductivity is highly likely to be realized. The superconducting order parameter does not change its sign on the Fermi surfaces, but it does change between the electron and hole Fermi surfaces. Consequently, the probable pairing symmetry is always "a nodeless extended s-wave symmetry (more specifically, an s_{+-}-wave symmetry)" over the whole parameter region that we investigated. It is suggested that the 2-band model is insufficient to explain the high values of Tc.
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