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Biomedical subjects

Takumi Yoshida

Publications and source records attributed to Takumi Yoshida.

14 recordsLinked to original sources
PubMed2006

Prevalence of hepatitis E virus infection in regular hemodialysis patients.

The percentage of patients infected with blood-borne diseases, including hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, is high in patients undergoing hemodialysis regularly. Hepatitis E virus (HEV) is transmitted via the fecal-oral route, and blood-borne HEV infection has also been reported recently. On the basis of these findings, we investigated the actual status of HEV infection in regular hemodialysis patients. Out of 1077 patients undergoing hemodialysis at two key hospitals and three outpatient hemodialysis clinics, 300 were randomly selected as the subjects. Among these 300 hemodialysis patients, 19.0% were IgG-type anti-HEV antibody-positive. The percentage of HEV-infected patients increased with patient age and it was particularly high in patients 40 years of age or older. The percent IgG-type anti-HEV antibody positivity was not significantly different (P = 0.14) between anti-HCV antibody-positive patients (27.8%) and anti-HCV antibody-negative patients (17.8%). The percentage of HEV-infected patients among the hemodialysis patients was higher than that previously reported among patients with healthy kidneys. No correlation was observed between the percentage of HEV-infected patients and HCV infection incidence or a history of blood transfusion. The percent IgG-type anti-HEV antibody positivities were significantly different among the facilities. It was impossible to specify the route of infection, and the correlation between the incidence of infection and hemodialysis therapy was not clear. Because more routes of infection are possible for patients undergoing dialysis than for persons with normal kidney function, it seems necessary to analyze the significance of infection incidence, the route of infection and infection prevention measures.

Chi-Square Distribution↗
PubMed2005

Klotho reduces apoptosis in experimental ischaemic acute renal failure.

BACKGROUND: Klotho is associated with the suppression of several ageing phenotypes. Because high klotho gene expression was detected in the kidney and several studies have found altered expression in animal models, we explored the physiological relevance of klotho expression in the kidney under renal ischemia reperfusion injury (IRI). METHODS: Male Wistar rats were subjected to bilateral renal ischemia or sham operation, followed by reperfusion for 6, 12 or 24 h, or 2 to 10 days. Renal expression of klotho was assessed by real-time PCR or Western blotting. Creatinine levels were determined. Immunohistochemical studies and TUNEL staining were performed. An adenovirus harbouring the mouse klotho gene (ad-kl) was intravenously administered to one group of rats before renal IRI. RESULTS: Renal klotho mRNA and protein expressions were significantly reduced in IRI rats the first day after ischemia. Pre-treatment with ad-kl resulted in a robust induction of klotho mRNA and protein in the liver but not in the kidney. Ad-kl gene transfer improved serum creatinine and the histological changes. Apoptosis induced by IRI was attenuated following ad-kl administration. CONCLUSION: The data suggest klotho to be involved in the pathophysiology of IRI. Downregulation of renal klotho exacerbates ischaemic acute renal failure, and klotho gene induction has therapeutic potential in managing ischaemic renal damage.

Acute Kidney Injury↗
PubMed2005

CD2AP expression in a renal ischemia/reperfusion injury model and analysis of its related genes using overexpression and RNA interference technique.

BACKGROUND: CD2-associated protein (CD2AP) is a ubiquitously expressed 80-kDa intracellular protein, and has been speculated to act as an intracellular signaling pathway between plasma membrane proteins and cytoskeleton proteins. CD2AP expression has been reported in both the glomerulus and tubular epithelium in the kidney, and CD2AP knockout mice exhibit congenital nephrotic syndrome. However, the precise properties and its role in the renal tubules have not been clarified. METHODS: We used an established rat model of ischemic/reperfusion renal injury (IRI) to examine the expression of CD2AP by real-time PCR, Western blotting, and immunohistochemistry. We also investigated the expression of genes related to apoptosis and cell proliferation in mouse collecting duct-derived cells (M1 cells) transfected with full-length of CD2AP cDNA or short interfering RNA. RESULTS: CD2AP mRNA and protein expression had significantly increased in the IRI kidney. Real-time PCR indicated that expression of genes regulating apoptosis, such as B-Raf and Caspase-12, and genes regulating cell proliferation factors, CDC2, was decreased in CD2AP-overexpressing M1 cells and increased in CD2AP-interfered M1 cells. CONCLUSIONS: These results suggest that CD2AP expression was increased following renal ischemia and that CD2AP may be related to the process of cell repair and/or cell differentiation following injury.

Adaptor Proteins, Vesicular Transport↗
PubMed2005

Oxidative stress decreases klotho expression in a mouse kidney cell line.

BACKGROUND/AIMS: Defects in klotho gene expression in the mouse result in a syndrome that resembles human aging. We recently identified expression of klotho in a mouse inner medullary collecting duct (mIMCD3) cell line for the first time, and in the present study we explored the physiological relevance of the regulation of klotho expression in the presence of oxidant stress injury. METHODS: Klotho expression was analyzed by real-time PCR, Western blot, and immuocytochemical staining during exposure to hydrogen peroxide (H2O2). Overexpression of the klotho gene was induced by klotho adenoviruses, and the number of apoptotic cells was counted by flowcytometry. RESULTS: Oxidant stress injury by H2O2 dose-dependently reduced klotho expression and diminished klotho staining. There were fewer apoptotic cells among the klotho-transfected cells than among the control cells. CONCLUSION: Klotho is expressed in cell line mIMCD3, and the klotho gene may be involved in the process of oxidative stress injury and apoptosis in this cell line.

Animals↗
PubMed2005

Efficacy and safety of intravenous theophylline administration for treatment of mild acute exacerbation of bronchial asthma.

OBJECTIVE: The present study was designed to evaluate the efficacy and safety of intravenously administered theophylline (IAT) for the treatment of an acute exacerbation of bronchial asthma. The theophylline was solubilized and not combined with ethylenediamine. METHODOLOGY: The subjects were 22 asthmatic patients with mild acute exacerbation of bronchial asthma. All patients had been taking oral sustained-release theophylline and their serum concentrations of theophylline were measured. The 16 patients whose serum theophylline concentrations were <13 microg/mL were randomly selected and treated with IAT (200 mg theophylline in 200 mL saline) for 2 h. Six patients were randomly selected as controls and received 200 mL of saline. Pulmonary function and asthma severity (Borg scale) before and after treatment were measured. RESULTS: After IAT, both PEF (before IAT, 313+/-79 L/min; after IAT, 335+/-107; P<0.05) and FEV(1) (before IAT, 1.66+/-0.47 L; after IAT, 1.83+/-0.44; P<0.05) increased significantly. Furthermore, their severity of asthma as assessed by the Borg scale (before IAT, 2.5+/-1.2; after IAT, 1.3+/-1.0; P<0.05) improved significantly. In contrast, neither FEV(1), PEF, severity of asthma or Borg scale changed significantly in the group who only received saline. None of the patients treated in this study had any adverse effects. CONCLUSION: These results suggest that IAT is useful for patients with mild acute exacerbation of bronchial asthma and is safe if serum theophylline concentrations are measured.

Acute Disease↗
PubMed2004

Osmoadaptation-related genes in inner medulla of mouse kidney using microarray.

To distinguish biological molecular processes of osmotic stress occurring in inner medulla, we utilized microarrays to monitor expression profiles. RNAs from three segments (cortex, outer medulla, and inner medulla) of mouse kidney were isolated and applied to microarrays. We found 35 genes expressed highly in inner medulla. Next, microarrays for the RNAs from mouse medullary collecting duct cell line (mIMCD) cells and osmotically adapted mIMCD cells (HT cells) were performed (designed as resistant to 1270mOsm/H(2)O). Of 35 genes highly expressed in inner medulla, 6 genes such as; B-cell translocation gene protein (BTG), myc-basic motif homologue, gelsolin, cell surface glycoprotein, laminin beta2, and tubulo-interstitial nephritis antigen, were also expressed highly in HT cells. Using real-time PCR, we confirmed the expression of six genes. Additionally acute osmotic stress induced the BTG. By comparing the inner medulla to a mIMCD3, we identified genes which respond to acute and chronic hyperosmotic stress.

Adaptation, Physiological↗
PubMed2004

[Functional analysis of the left-right determinant inv (inversion of embryonic turning) gene].

We identified the inv gene that encodes left and right asymmetry and regulates kidney development based on the information of the inv mutant mouse. However, functional properties and the modulator of gene expression of inv have been unclear. We used the tissue injury model for assessing the functional roles of inv in ischemia reperfusion injury (IRI). The kidney tissue taken from rats with IRI showed reciprocal changes in mRNA expression of inv: a 0.25-fold decrease at 6 hours and then a gradual increase to a maximum 1.8-fold rise at 10 days of reperfusion. Next, oxidative stress was induced by exposing mouse inner medullary collecting duct (mIMCD-3) cells to hydrogen peroxide(H2O2) in the medium. Real-time PCR showed that mRNA expression of inv decreased 0.52-fold at 3 hours with 0.2 mM H2O2 in the medium, and then increased 3.1-fold at 24 hours with 0.1 mM H2O2 in the medium. RNA interference (RNAi) is a powerful tool to inhibit gene expression in experimental model systems. We knocked down inv gene expression in mIMCD-3 cells using RNAi to investigate the function of the inv gene. We designed a small interfering RNA (siRNA) to target the coding region of inv (inv-siRNA) and random-sequence scrambled siRNA(control siRNA). mIMCD-3 cells transfected with either the inv-siRNA or control siRNA were observed by microscopy. The cells transfected with inv-siRNA progressively lost cell-to-cell contact and the cell population significantly diminished approximately 48 hours post-transfection. The changes in gene expression profile were observed at time points (36 hours) using real-time PCR-based gene screening with categorized primer sets. Several genes related to structural protein of the matrix were downregulated. In contrast, repairing related genes were upregulated. In conclusion, gene expression of inv was modulated under oxidative stress and the inv gene may play a role in repairing and regenerating renal epithelial cells.

Animals↗
PubMed2002

Discovery of molecular mechanisms of neuroprotection using cell-based bioassays and oligonucleotide arrays.

Oxidative injury and the resulting death of neurons is a major pathological factor involved in numerous neurodegenerative diseases. However, the development of drugs that target this mechanism remains limited. The goal of this study was to test a compound library of approved Food and Drug Administration drugs against a hydrogen peroxide-induced oxidant injury model in neuroblastoma cells. We identified 26 neuroprotective compounds, of which megestrol, meclizine, verapamil, methazolamide, sulindac, and retinol were examined in greater detail. Using large-scale oligonucleotide microarray analysis, we identified genes modulated by these drugs that might underlie the cytoprotection. Five key genes were either uniformly upregulated or downregulated by all six drug treatments, namely, tissue inhibitor of matrix metalloproteinase (TIMP1), ret-proto-oncogene, clusterin, galanin, and growth associated protein (GAP43). Exogenous addition of the neuropeptide galanin alone conferred survival to oxidant-stressed cells, comparable to that seen with the drugs. Our approach, which we term "interventional profiling," represents a general and powerful strategy for identifying new bioactive agents for any biological process, as well as identifying key downstream genes and pathways that are involved.

Biological Assay↗
PubMed2002

Global analysis of gene expression in renal ischemia-reperfusion in the mouse.

Ischemia-induced acute renal failure (ARF) is a relatively common disorder with major morbidity and mortality. To study global gene expression during ARF, 6-week-old C57BL/6 male mice underwent 30 min of bilateral renal ischemia followed by reperfusion [I/R] or sham operation. Oligonucleotide microarrays [Affymetrix] with approximately 10,000 genes, 6,643 of which were present in mouse kidney, were used to analyze mRNA expression for up to 4 days following I/R. Fifty-two genes at day 1 and 40 at day 4 were up-regulated more than 4-fold [400%]. Seventy genes at day 1 and 30 genes at day 4 were down-regulated to under 0.25-fold from baseline [25%]. Real-time quantitative RT-PCR confirmed changes in expression for 8 genes of interest. Most of the induced transcripts are involved in cell structure, extracellular matrix, intracellular calcium binding, and cell division/differentiation. Our data identified several novel genes that may be important in renal repair after ischemia.

ADP-Ribosylation Factor 6↗
PubMed2002

Monitoring changes in gene expression in renal ischemia-reperfusion in the rat.

BACKGROUND: Although acute renal failure (ARF) is a relatively common disorder with major morbidity and mortality, its molecular basis remains incompletely defined. The present study examined global gene expression in the well-characterized ischemia-reperfusion model of ARF using DNA microarray technology. METHODS: Male Wistar rats underwent bilateral renal ischemia (30 min) or sham operation, followed by reperfusion for 1, 2, 3 or 4 days. Plasma creatinine increased approximately fivefold over baseline, peaking on day 1. Renal total RNA was used to probe cDNA microarrays. RESULTS: Alterations in expression of 18 genes were identified by microarray analysis. Nine genes were up-regulated (ADAM2, HO-1, UCP-2, and thymosin beta4 in the early phase and clusterin, vanin1, fibronectin, heat-responsive protein 12 and FK506 binding protein in the established phase), whereas another nine were down-regulated (glutamine synthetase, cytochrome p450 IId6, and cyp 2d9 in the early phase and cyp 4a14, Xist gene, PPARgamma, alpha-albumin, uromodulin, and ADH B2 in the established phase). The identities of these 18 genes were sequence-verified. Changes in gene expression of ADAM2, cyp2d6, fibronectin, HO-1 and PPARgamma were confirmed by quantitative real-time polymerase chain reaction (PCR). ADAM2, cyp2d6, and PPARgamma have not previously been known to be involved in ARF. CONCLUSION: Using DNA microarray technology, we identified changes in expression of 18 genes during renal ischemia-reperfusion injury in the rat. We confirmed changes in five genes (fibronectin, ADAM2, cyp 2d6, HO-1 and PPARgamma) by quantitative real-time PCR. Several genes, not previously been identified as playing a role in ischemic ARF, may have importance in this disease.

ADAM Proteins↗
PubMed2002

Global analysis of gene expression: methods, interpretation, and pitfalls.

Over the past 15 years, global analysis of mRNA expression has emerged as a powerful strategy for biological discovery. Using the power of parallel processing, robotics, and computer-based informatics, a number of high-throughput methods have been devised. These include DNA microarrays, serial analysis of gene expression, quantitative RT-PCR, differential-display RT-PCR, and massively parallel signature sequencing. Each of these methods has inherent advantages and disadvantages, often related to expense, technical difficulty, specificity, and reliability. Further, the ability to generate large data sets of gene expression has led to new challenges in bioinformatics. Nonetheless, this technological revolution is transforming disease classification, gene discovery, and our understanding of regulatory gene networks.

Computational Biology↗
PubMed2001

DNA microarray analysis of complex biologic processes.

DNA microarrays, or gene chips, allow surveys of gene expression, (i.e., mRNA expression) in a highly parallel and comprehensive manner. The pattern of gene expression produced, known as the expression profile, depicts the subset of gene transcripts expressed in a cell or tissue. At its most fundamental level, the expression profile can address qualitatively which genes are expressed in disease states. However, with the aid of bioinformatics tools such as cluster analysis, self-organizing maps, and principle component analysis, more sophisticated questions can be answered. Microarrays can be used to characterize the functions of novel genes, identify genes in a biologic pathway, analyze genetic variation, and identify therapeutic drug targets. Moreover, the expression profile can be used as a tissue or disease "fingerprint." This review details the fabrication of arrays, data management tools, and applications of microarrays to the field of renal research and the future of clinical practice.

Drug Design↗
PubMedDate not supplied

DNA microarrays: applicability to renal physiology and disease.

The utilization of DNA microarray is increasing in all areas of medical research as evidenced by the exponential increase in the number of publications on MedLine. Improvements in DNA microarray technology and the bioinformatic techniques for data analysis continue to take place and result in improved reliability, reproducibility, and volume of data. Replicate analysis remains important in order to allow statistical examination of significance. Expression of key genes should also be confirmed by alternative techniques. Single microarray experiments yield such vast amounts of data that shortage of manpower is the limiting factor to progression of full scientific discovery. Sharing of microarray data on the internet and its distribution to a broader scientific community will help overcome this manpower shortage. Currently, DNA microarray technology serves as a research tool. Ultimately, microarray technology may be used widely in the clinical setting as fingerprinting of cells, tissue, and disease states, though more targeted strategies using a limited repertoire of genes may be most valuable.

Animals↗