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Kentaro Imai,
Tomohiko Koibuchi,
Takashi Kumagai, Takuya Maeda,
Yoshio Osada,
Nobuo Ohta,
Michiko Koga,
Hitomi Nakamura,
Toshiyuki Miura,
Aikichi Iwamoto,
Takeshi Fujii
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ABSTRACT: The case of a 25-year-old Japanese male who had cerebral schistosomiasis caused by Schistosoma haematobium is reported here. Although serum antibody tests showed a cross-reaction with other helminths and no ova were excreted in urine or feces, the existence of Schistosoma haematobium in the brain was confirmed by PCR analysis.
Journal of clinical microbiology 08/2011; 49(10):3703-6. · 4.16 Impact Factor
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ABSTRACT: An Indian woman with multiple and nodular cerebral lesions presenting epithelioid granulomas was diagnosed as suspected malignant tumours and the biopsy was carried at local hospital in Japan. The specimen was pathologically diagnosed as tuberculoma. However, due to her nationality, the authors suspected it to be neurocysticercosis (NCC) and carried out serology and applied mitochondrial DNA analysis of Taenia solium. These diagnostic tools revealed it as NCC radiologically and pathologically mimicking central nervous tuberculomas. Molecular confirmation of NCC cases is strongly recommended when we can get the biopsy specimens.
Case Reports 01/2011; 2011.
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ABSTRACT: Bioinformatics research on Plasmodium falciparum revealed two isoforms of pyruvate kinase: type-I and type-II enzymes. The type-I enzyme shows typical glycolytic properties, while type-II enzyme is involved in fatty acid type-II biosynthesis and has been predicted to localize to the apicoplast with the targeting signal in its N-terminus. The type-I and type-II isoforms have the same evolutionary origin as Toxoplasma gondii isozymes, TgPyKI and TgPyKII, respectively; however, TgPyKII localizes to both the mitochondrion and the apicoplast. Accordingly, we made a recombinant full length of P. falciparum pyruvate kinase type-II protein using a wheat germ cell-free expression system and obtained a specific antibody against the type-II protein. Fluorescent microscopic analysis revealed that P. falciparum type-II enzyme was localized only to the apicoplast, not to the mitochondrion. The data suggest differences in localization and metabolic pathways between P. falciparum and T. gondii pyruvate kinase isoforms.
Parasitology International 11/2008; 58(1):101-5. · 2.13 Impact Factor
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ABSTRACT: We previously reported a cytosolic pyruvate kinase (EC 2.7.1.40) from Toxoplasma gondii (TgPyKI) that differs from most eukaryotic pyruvate kinases in being regulated by glucose 6-phosphate rather than fructose 1,6-diphosphate. Another putative pyruvate kinase (TgPyKII) was identified from parasite genome, which exhibits 32% amino acid sequence identity to TgPyKI and retains pyruvate kinase signature motifs and amino acids essential for substrate binding and catalysis. Whereas TgPyKI is most closely related to plant/algal enzymes, phylogenetic analysis suggests a proteobacterial origin for TgPyKII. Enzymatic characterization of recombinant TgPyKII shows a high pH optimum at 8.5, and a preference for GDP as a phosphate recipient. Catalytic activity is independent of K+, and no allosteric or regulatory effects were observed in the presence of fructose 1,6-diphosphate, fructose 2,6-diphosphate, glucose 6-phosphate, ribose 5-phosphate, AMP, or ATP. Unlike TgPyKI, native TgPyKII activity was exclusively associated with the membranous fraction of a T. gondii tachyzoite lysate. TgPyKII possesses a long N-terminal extension containing five putative start codons before the conserved region and localizes to both apicoplast and mitochondrion by immunofluorescence assay using native antibody and fluorescent protein fusion to the N-terminal extension. Further deletional and site-directed mutagenesis suggests that a translation product from 1st Met is responsible for the localization to the apicoplast, whereas one from 3rd Met is for the mitochondrion. This is the first study of a potential mitochondrial pyruvate kinase in any system.
Journal of Biological Chemistry 06/2008; 283(20):14041-52. · 4.77 Impact Factor
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ABSTRACT: During cerebral cortical development, the majority of excitatory neurons are born near the ventricle and migrate radially toward the marginal zone (MZ). Since the cells invariably stop migrating beneath the MZ, neurons are aligned in an "inside-out" manner in the cortical plate (CP); that is, the early-born and late-born neurons are ultimately positioned in the deep and superficial layers, respectively. Since dramatic morphological changes occur in cells beneath the MZ, several events critical for proper neuronal maturation and layer formation must take place. In this study, we screened for molecules strongly expressed beneath the MZ, and identified 28 genes that are preferentially expressed in the upper half of the mouse CP on both embryonic day (E) 16.5 and E18.5. Expression analyses in reeler and yotari mice, in which neurons terminate migration throughout the CP, suggested that these genes were indeed related to the events beneath the MZ rather than unrelatedly induced by the structures near the brain surface. Pathway analyses suggested calcium signaling to have an important role in cells beneath the MZ. The gene list presented here will be useful for clarifying the molecular mechanisms that control cortical development.
Neuroscience Research 03/2008; 60(2):135-46. · 2.25 Impact Factor
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ABSTRACT: This report describes a case of hepatic phase Fasciola hepatica infection presenting huge and multilocular lesions. The unique radiological findings mimicked hydatid diseases and also cystic liver neoplasm. Fascioliasis should be included in the differential diagnosis for cystic liver diseases.
Internal Medicine 02/2008; 47(5):449-52. · 0.94 Impact Factor
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ABSTRACT: Abstract
Background
Development of multicellular organisms proceeds from a single fertilized egg as the combined effect of countless numbers of cellular interactions among highly dynamic cells. Since at least a reminiscent pattern of morphogenesis can be recapitulated in a reproducible manner in reaggregation cultures of dissociated embryonic cells, which is known as cell sorting, the cells themselves must possess some autonomous cell behaviors that assure specific and reproducible self-organization. Understanding of this self-organized dynamics of heterogeneous cell population seems to require some novel approaches so that the approaches bridge a gap between molecular events and morphogenesis in developmental and cell biology. A conceptual cell model in a computer may answer that purpose. We constructed a dynamical cell model based on autonomous cell behaviors, including cell shape, growth, division, adhesion, transformation, and motility as well as cell-cell signaling. The model gives some insights about what cellular behaviors make an appropriate global pattern of the cell population.
Results
We applied the model to "inside and outside" pattern of cell-sorting, in which two different embryonic cell types within a randomly mixed aggregate are sorted so that one cell type tends to gather in the central region of the aggregate and the other cell type surrounds the first cell type. Our model can modify the above cell behaviors by varying parameters related to them. We explored various parameter sets with which the "inside and outside" pattern could be achieved. The simulation results suggested that direction of cell movement responding to its neighborhood and the cell's mobility are important for this specific rearrangement.
Conclusion
We constructed an in silico cell model that mimics autonomous cell behaviors and applied it to cell sorting, which is a simple and appropriate phenomenon exhibiting self-organization of cell population. The model could predict directional cell movement and its mobility are important in the "inside and outside" pattern of cell sorting. Those behaviors are altered by signal molecules and consequently affect the global pattern of the cell sorting. Our model is also applicable to other developmental processes beyond cell sorting.
BMC Systems Biology. 01/2007;
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ABSTRACT: Oligonucleotide-based microarrays, such as GeneChip, are widely used to determine the large-scale gene expression profiles. However, GeneChip only provides information on the identity of the molecules, and the investigator must obtain each cDNA clone for further analyses. In this study, we devised a program which enables us to correlate a large number of DNA accession numbers to the FANTOM (functional annotation of the mouse) full-length mouse cDNA clone set, and made a correlative table between mouse GeneChip clones and FANTOM clones. This allows easy identification of the corresponding FANTOM clone for each GeneChip clone, even if the sequence of the GeneChip clone does not directly match the FANTOM clone. Using this table, for example, a large number of in situ hybridization probes can be synthesized easily, because the FANTOM clones are flanked by T3/T7 promoters on both ends. In addition, we further developed a program which retrieves the amino acid sequence (AA Seq) for each clone, even for the FANTOM clones that lack the AA Seq description, and classifies the proteins automatically. As an example, we devised a correlation table with predictions of the secretory or transmembrane molecules. The correlation table is useful for a large-scale screening of molecules involved in cell-cell communication in various biological processes. The full correlation table for the GeneChip clones is available at http://www.kjm.keio.ac.jp/past/55/3/correlation_table1.html.
The Keio Journal of Medicine 10/2006; 55(3):107-10.
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ABSTRACT: Radial glial cells are the main component of the embryonic cortical ventricular zone (VZ), producing deep-layer excitatory neurons in the early stage and upper-layer excitatory neurons in the late stage of development. Previous studies have suggested that the laminar fate of deep-layer neurons might be determined by early-stage-specific secretory or transmembrane molecules (S/TMs) in the VZ. However, the different properties required to produce the different types of neurons in early-stage and late-stage VZ cells are largely unknown. Herein, we investigated the stage-dependent transcriptional profiles of the ventricular side of the mouse cortex, which was manually dissected at embryonic day (E)12, E14 and E16, and identified 3985 'VZ-enriched' genes, regulated stage-dependently, by GeneChip analysis. These molecules were classified into nine types based on stage-dependent regulation patterns. Prediction programs for the S/TMs revealed 659 'VZ-enriched' S/TMs. In situ hybridization and real-time PCR analysis for several of these molecules showed results consistent with the statistical analysis of the GeneChip experiments. Moreover, we identified 17 cell cycle-related early-stage and 'VZ-enriched' molecules. These molecules included not only those involved in cell cycle progression, but also essential molecules for DNA double-strand break repair, such as Rad51 and Rpa1. These results suggest that the early stage-VZ cells, which produce both deep- and upper-layer neurons, and the late-stage VZ cells, which produce only upper-layer neurons, are intrinsically different. The gene lists presented here will be useful for the investigation of stage-dependent changes in VZ cells and their regulatory mechanisms in the developing cortex.
European Journal of Neuroscience 02/2006; 23(2):296-308. · 3.63 Impact Factor
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Nippon rinsho. Japanese journal of clinical medicine 08/2005; 63 Suppl 7:277-9.
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ABSTRACT: We have cloned a cDNA encoding Toxoplasma gondii pyruvate kinase and obtained the full-length recombinant enzyme with a calculated molecular mass of 57.5 kDa. The predicted amino acid sequence of T. gondii pyruvate kinase exhibited a highest identity (63%) to that of Eimeria tenella pyruvate kinase and a lower identity of less than 25% to the pyruvate kinases from other organisms. Southern blot analysis indicated that the pyruvate kinase gene existed as a single copy in the T. gondii tachyzoite. The active recombinant enzyme contained four subunits and produced a strongly sigmoid saturation curve with phosphoenolpyruvate as the variable substrate. Fructose 1,6-diphosphate, a general activating factor of pyruvate kinase in most species, did not affect the enzyme activity. However, glucose 6-phosphate radically activated the enzyme. Fructose 2,6-diphosphate suppressed the reaction velocity at a higher concentration of phosphoenolpyruvate. These properties indicate that pyruvate kinase activity in T. gondii is regulated by unusual phosphorylated sugars.
Parasitology Research 04/2003; 89(4):259-65. · 2.15 Impact Factor
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Takuya Maeda
Nippon rinsho. Japanese journal of clinical medicine 03/2003; 61 Suppl 2:603-7.
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ABSTRACT: We have cloned the hexokinase [E.C. 2.7.1.1] gene of Toxoplasma gondii tachyzoite and obtained an active recombinant enzyme with a calculated molecular mass of 51,465Da and an isoelectric point of 5.82. Southern blot analysis indicated that the hexokinase gene existed as a single copy in the tachyzoites of T. gondii. The sequence of T. gondii hexokinase exhibited the highest identity (44%) to that of Plasmodium falciparum hexokinase and lower identity of less than 35% to those of hexokinases from other organisms. The specific activity of the homogeneously purified recombinant enzyme was 4.04 micromol/mg protein/min at 37 degrees C under optimal conditions. The enzyme could use glucose, fructose, and mannose as substrates, though it preferred glucose. Adenosine triphosphate was exclusively the most effective phosphorus donor, and pyrophosphate did not serve as a substrate. K(m) values for glucose and adenosine triphosphate were 8.0+/-0.8 microM and 1.05+/-0.25mM, respectively. No allosteric effect of substrates was observed, and the products, glucose 6-phosphate and adenosine diphosphate, had no inhibitory effect on T. gondii hexokinase activity. Other phosphorylated hexoses, fructose 6-phosphate, trehalose 6-phosphate which is an inhibitor of yeast hexokinase, and pyrophosphate, also did not affect T. gondii hexokinase activity. Native hexokinase activity was recovered in both the cytosol and membrane fractions of the whole lysate of T. gondii tachyzoites. This result suggests that T. gondii hexokinase weakly associates with the membrane or particulate fraction of the tachyzoite cell.
International Journal for Parasitology 08/2002; 32(8):961-7. · 3.39 Impact Factor
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ABSTRACT: We report here a case of Pneumocystis jiroveci pneumonia (PCP) in an acquired immune deficiency syndrome (AIDS) patient with multiloculated cavitary lesions. Time-course analysis of chest computed tomography (CT) showed spontaneous ballooning of cavities and their disappearance after completion of PCP treatment. The characteristic radiological findings as well as histological features of a cavitary lesion suggested that check-valve phenomenon in small airways might explain the pathogenesis of cavities in this case.
European Journal of Radiology Extra.
