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N Chiba

Publications and source records attributed to N Chiba.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Modularization by the open standard. (II)].

In recent years, accompanied by the marvelous development and spread of Laboratory Automation System(LAS), the NCCLS is now proposing five international standards for laboratory automation. We have based our laboratory on these "NCCLS standards of laboratory automation", we take these standards ahead first, and we now propose an open standard called "Open LA 21", to establish more detailed standard replacing the NCCLS laboratory automation standards.

Automation↗
PubMed1999

Determination of 5-hydroperoxyeicosatetraenoic acid produced in rat basophilic leukemia cell line RBL-2H3 by high-performance liquid chromatography with chemiluminescence detection.

A simple and sensitive method, applicable to quantification of 5-hydroperoxyeicosatetraenoic acid (5-HPETE) produced in cells has been developed using high-performance liquid chromatography on a silica gel column with chemiluminescence detection. 5-HPETE was clearly separated from other positional isomers of HPETEs and hydroxyeicosatetraenoic acids with hexane-isopropanol-acetic acid (97:3:0.01, v/v) as the mobile phase. The lower limit of detection was about 100 pg. 5-HPETE produced in 10(7) cells of RBL-2H3 cells stimulated with A23187 was determined as 480+/-30 pg. In the present study, 5-HPETE, which occurs naturally, was detected and quantitated for the first time in intact cells.

Animals↗
PubMed1999

Microanalysis of a selective potent anti-Helicobacter pylori compound in a Brazilian medicinal plant, Myroxylon peruiferum and the activity of analogues.

A selective potent anti-Helicobacter pylori isoflavone was isolated from a Brazilian Medicinal Plant, Myroxylon peruiferum. The isolation bioassay-guided and the characterization of an active anti-H. pylori constituent was performed using the methanol extract of plant of minute amount. The active compound was identified as cabreuvin (1), an isoflavone derivative. The structure-activity relationships of several related compounds were also investigated.

Anti-Bacterial Agents↗
PubMed1999

Protection against tick-borne encephalitis virus isolated in Japan by active and passive immunization.

In order to establish a firm preventive measure for tick-borne encephalitis (TBE) in Japan, we evaluated the immune response of European vaccine against Japanese TBE virus strain (Oshima 5-10) for man and mouse. Furthermore, the efficacy of pre- and post-exposure protection by a polyclonal rabbit anti-TBE virus serum was examined in the mouse model. 80% of vaccinees seroconverted against Oshima 5-10 strain after the 2nd immunization of vaccine and the remaining 20% seroconverted after the 3rd immunization. Two persons with pre-existing anti-Japanese encephalitis virus (JEV) antibodies showed low immune responses against TBE virus. In mouse vaccination and challenge tests, efficient protection was observed in mice challenged with lethal doses of Oshima 5-10 strain as well as those observed in mice with the Western subtype and the Far Eastern subtype of TBE strains. Pre-exposure treatment with rabbit anti-TBE virus serum provided complete protection against lethal challenge with Oshima 5-10 strain. For post-exposure treatment with the antibody, significant protection was observed when mice were treated 24 h after virus challenge, whereas it was not observed 48 h after virus challenge. reserved.

Animals↗
PubMed1999

Pathogenicity of tick-borne encephalitis virus isolated in Hokkaido, Japan in mouse model.

The pathogenic characteristics of tick-borne encephalitis (TBE) virus strain (Oshima 5-10) isolated from a sentinel dog in Hokkaido, Japan, was compared by use of a mouse model with several inoculation routes to other strains of TBE virus (the Far Eastern subtype; Sofjin strain and the Western subtype; Hochosterwitz strain) and TBE complex virus (Langat virus; TP-21 strain). The degree of neuroinvasiveness of the strains in mice subcutaneously (s.c.) inoculated was Sofjin equaled Hochosterwitz which was greater than Oshima and TP-21, respectively. Neurovirulence, as determined after intracerebral inoculation was Sofjin > Oshima = Hochosterwitz > TP-21. Virus replication in the brains of mice s.c. or intracerebrally inoculated with Oshima strain was slower and of lower titer than that of Sofjin strain. Histopathological findings indicated that subarachnoid infiltration of mononuclear cells prior to necrosis of the cerebrum was characteristic in Oshima strain. These findings indicated that the Oshima strain possessed a pathogenic potential common to TBE viruses and is less virulent for mice as compared with the two other TBE strains examined.

Animals↗
PubMed1999

Mitochondrial phospholipid hydroperoxide glutathione peroxidase plays a major role in preventing oxidative injury to cells.

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is synthesized as a long form (L-form; 23 kDa) and a short form (S-form; 20 kDa). The L-form contains a leader sequence that is required for transport to mitochondria, whereas the S-form lacks the leader sequence. A construct encoding the leader sequence of PHGPx tagged with green fluorescent protein was used to transfect RBL-2H3 cells, and the fusion protein was transported to mitochondria. The L-form of PHGPx was identified as the mitochondrial form of PHGPx and the S-form as the non-mitochondrial form of PHGPx since preferential enrichment of mitochondria for PHGPx was detected in M15 cells that overexpressed the L-form of PHGPx, whereas no similar enrichment was detected in L9 cells that overexpressed the S-form. Cell death caused by mitochondrial injury due to potassium cyanide (KCN) or rotenone (chemical hypoxia) was considerably suppressed in the M15 cells, whereas the L9 cells and control RBL-2H3 cells (S1 cells, transfected with the vector alone) succumbed to the cytotoxic effects of KCN. Flow cytometric analysis showed that mitochondrial PHGPx suppressed the generation of hydroperoxide, the loss of mitochondrial membrane potential, and the loss of plasma membrane integrity that are induced by KCN. Mitochondrial PHGPx might prevent changes in mitochondrial functions and cell death by reducing intracellular hydroperoxides. Mitochondrial PHGPx failed to protect M15 cells from mitochondrial injury by carbonyl cyanide m-chlorophenylhydrazone, which directly reduces membrane potential without the generation of hydroperoxides. M15 cells were more resistant than L9 cells to cell death caused by direct damage to mitochondria and to extracellular oxidative stress. L9 cells were more resistant to tert-butylhydroperoxide than S1 cells, whereas resistance to t-butylhydroperoxide was even more pronounced in M15 cells than in L9 cells. These results suggest that mitochondria might be a target for intracellular and extracellular oxidative stress and that mitochondrial PHGPx, as distinct form non-mitochondrial PHGPx, might play a primary role in protecting cells from oxidative stress.

Animals↗
PubMed1999

Inflammatory and immunopharmacological activities of meta-periodate oxidized zymosan.

Zymosan (ZYM), a strong complement-activating yeast cell preparation composed mainly of mannan and beta-glucan moieties, is a potent inflammatory substance with immunopharmacological activity. We previously analyzed the metabolism of ZYM in mice and found that it was deposited in liver and spleen for at least several months and then gradually oxidatively degraded. In this paper, we prepared oxidized ZYM by sodium metaperiodate oxidation (NaIO4) and borohydride reduction (I/B-ZYM) and/or limited hydrolysis of oxidized moieties (I/B/H-ZYM). Activities of the resulting products were assessed by (i) vascular permeability in mice, (ii) H2O2 synthesis by macrophages, (iii) TNF-alpha synthesis by macrophages, and (iv) reactivity to anti-ZYM sera. As a general trend, NaIO4, oxidation products exhibited reduced, but still significant, activity. Interestingly, the H2O2 production induced by I/B/H-ZYM was significantly reduced after extensive sonication. Antagonist(s) for H2O2 synthesis were concomitantly solubilized by sonication of I/B/H-ZYM. On the contrary, TNF-alpha production induced by I/B/H-ZYM was comparable with that of ZYM. These facts strongly suggest that highly branched 1,3-beta- and 1,6-beta-glucosidic linkages resistant to NaIO4 oxidation are important for biological activity of ZYM. Further, the minimal structure in ZYM necessary for biological activity may depend on the activity tested.

Animals↗
PubMed1999

Cellular glutathione peroxidase as a predominant scavenger of hydroperoxyeicosatetraenoic acids in rabbit alveolar macrophages.

The cytosol of rabbit lung alveolar macrophages contains a high amount of peroxidase, which reduces 5-hydroperoxyeicosatetraenoic acid (5-HPETE) to 5-hydroxyeicosatetraenoic acid (5-HETE) in the presence of glutathione. This peroxidase was purified 69-fold to homogeneity with overall recovery of activity of 18.5%. The molecular mass of the enzyme was approximately 80 kDa by gel filtration, and emerged as a single band at 23.1 kDa under reducing condition by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The amino-terminal sequence of the purified peroxidase was completely identical to the sequence deduced from cellular glutathione peroxidase (cGPx) gene of rabbit liver. No other activity that reduces 5-HPETE to 5-HETE was observed during purification. These results suggest that cGPx plays an important role in metabolism of lipid hydroperoxides, especially HPETE, in lung alveolar macrophages.

Amino Acid Sequence↗
PubMed1998

AML1(-/-) embryos do not express certain hematopoiesis-related gene transcripts including those of the PU.1 gene.

The AML1 and PEBP2beta/CBFbeta genes encode the DNA-binding and non-binding subunits, respectively, of the heterodimeric transcription factor, PEBP2/CBF. Targeting each gene results in an almost identical phenotype, namely the complete lack of definitive hematopoiesis in the fetal liver on embryonic day 11.5 (E11.5). We examined and compared the expression levels of various hematopoiesis-related genes in wild type embryos and in embryos mutated for AML1 or PEBP2beta/CBFbeta. The RNAs were prepared from the yolk sacs of E9.5 embryos, from the aorta-gonad- mesonephros regions of E11.5 embryos and from the livers of E11.5 embryos and RT-PCR was performed to detect various gene transcripts. Transcripts were detected for most of the hematopoiesis-related genes that encode transcription factors, cytokines and cytokine receptors, even in tissues from homozygously targeted embryos. On the other hand, PU.1 transcripts were never detected in any tissue of AML1(-/-) or PEBP2beta/CBFbeta(-/-) embryos. In addition, transcripts for the Vav, flk-2/flt-3, M-CSF receptor, G-CSF receptor and c-Myb genes were not detected in certain tissues of the (-/-) embryos. The results suggest that the expression of a particular set of hematopoiesis-related genes is closely correlated with the PEBP2/CBF function.

Animals↗
PubMed1998

Overexpression of AML1 renders a T hybridoma resistant to T cell receptor-mediated apoptosis.

The AML1 gene, which encodes the DNA binding subunit of the heterodimeric transcription factor, PEBP2/CBF, is involved in several types of chromosomal translocations associated with human acute myeloid leukemia, and has been shown by gene targeting to be essential for the development of definitive hematopoiesis in the murine fetal liver. In addition, the gene is expressed abundantly in T lymphocytes and has been implicated in T cell specific gene expression. In the present study we examined the function of AML1 in T cell receptor (TCR)-mediated, Fas/Fas-ligand dependent apoptosis of a T hybridoma line, DO11.10. Several independent cell clones overexpressing the AML1 protein were isolated by transfecting AML1 cDNA into these cells. These clones possessed an increased level of PEBP2/CBF DNA binding activity and were found to be resistant to apoptosis induced by anti-CD3 antibody treatment. Northern blot analysis revealed that induction of the Fas-ligand transcript was markedly suppressed in the anti-CD3 treated clones. Instead, expression of IL-2 receptor alpha subunit (IL-2R alpha), which is a manifestation of proliferative TCR signaling, was induced. This was in contrast to the parental, anti-CD3 treated DO11.10 cells where induction of Fas-ligand but not of IL-2R alpha was observed. Resistance of the AML1 overexpressing cell clones to TCR-mediated apoptosis is most likely attributable to the lack of Fas-ligand induction, since simultaneous treatment with anti-CD3 and anti-Fas antibodies caused apoptosis of the clones. The overall results suggest that the AML1 protein may play a pivotal role in switching TCR signaling between apoptosis and cell proliferation in T lymphocytes.

Animals↗
PubMed1998

The chimeric protein, PEBP2 beta/CBF beta-SMMHC, disorganizes cytoplasmic stress fibers and inhibits transcriptional activation.

The chromosomal inversion 16(p13;q22) associated with human acute myeloid leukemia generates the chimeric PEBP2 beta/CBF beta-SMMHC gene. The PEBP2 beta/CBF beta portion of the chimeric polypeptide harbors most of the amino acid sequence of the PEBP2 beta/CBF beta protein, the non-DNA binding subunit of the heterodimeric transcription factor, PEBP2/CBF, whereas the SMMHC portion of the chimera consists of the rod domain of the smooth muscle myosin heavy chain molecule. In this study we examined the subcellular localization of the chimeric protein and its effect both on stress fibers and transcriptional activation by transfecting cDNA into tissue culture cells. The localization of the chimera was investigated by immunocytochemical staining of cells and was found to be both cytoplasmic and nuclear. One aspect of the effect of expression of the chimera was a drastic alteration of cell morphology. The cells appeared elongated and possessed long cytoplasmic processes. Double fluorescent labeling revealed disorganization of the stress fibers and an altered F-actin staining pattern in the transfected cells. Studies using a deletion mutant showed that both the PEBP2 beta/CBF beta and SMMHC domains are necessary for the induction of the morphological alteration. A significant proportion of the chimeric protein was retained in the cytoskeleton after detergent extraction of the cells and could be recuperated as a membrane fraction, suggesting that this is one of the probable sites of action of the PEBP2 beta/CBF beta-SMMHC protein. Another effect of the chimeric protein was inhibition of transcriptional activation dependent on the PEBP2/CBF binding DNA sequence. However, deregulation of PEBP2/CBF site dependent transcription by itself was not sufficient to induce cell morphological changes. Taken together, these results indicate that the PEBP2 beta/CBF beta-SMMHC chimeric protein acts at two levels, at the level of stress fiber organization and at the level of transcriptional activation. We suggest that the action of PEBP2 beta/CBF beta-SMMHC depends to a great extent on whether it is located in the cytoplasm or in the nucleus.

Acute Disease↗
PubMed1998

Identification of two alpha-subunit species of GTP-binding proteins, Galpha15 and Galphaq, expressed in rat taste buds.

We cloned cDNAs for two G protein alpha-subunits belonging to the Galphaq family, each capable of activating PLCbeta, from rat tongue. One is a Galphaq in the narrow sense, and the other, termed rat Galpha15, is a rat counterpart of mouse Galpha15, sharing an amino acid sequence similarity of 94%. RT-PCR and Northern blot analysis demonstrated that rat Galpha15 and Galphaq were distinctly expressed in tongue epithelia containing taste buds. Immunostaining also showed that rat Galpha15, together with the Galphaq, was localized mainly in taste buds. These studies suggest the possibility that these two Galpha proteins function for taste signal transduction in sensory cells.

Amino Acid Sequence↗
PubMed1998

Suppression of leukotriene formation in RBL-2H3 cells that overexpressed phospholipid hydroperoxide glutathione peroxidase.

The overexpression of phospholipid hydroperoxide glutathione peroxidase (PHGPx) by RBL-2H3 cells was used as the basis for an investigation of the effects of PHGPx on the formation of leukotrienes. The rates of production of leukotriene C4 (LTC4) and leukotriene B4 (LTB4) in cells that overexpressed PHGPx were 8 times lower than those in a control line of cells. The reduction in rates of production of leukotrienes apparently resulted from the increase in the PHGPx activity since control rates of formation of leukotrienes could be achieved in PHGPx-overexpressing cells upon inhibition of PHGPx activity by diethyl malate. The conversion of radioactively labeled arachidonic acid to intermediates in the lipoxygenase pathway, such as 5-hydroxyeicosatetraenoic acid (5-HETE), LTC4, and LTB4, was strongly inhibited in PHGPx-overexpressing cells that had been prelabeled with [14C]arachidonic acid. PHGPx apparently inactivated the 5-lipoxygenase that catalyzed the conversion of arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) since 5-HPETE is a common precursor of 5-HETE, LTC4, and LTB4. The rates of formation of LTC4 and LTB4 in PHGPx-overexpressing cells returned to control rates upon the addition of a small amount of 12-HPETE. Flow cytometric analysis revealed that the rapid burst of formation of lipid hydroperoxides induced by A23187 was suppressed in PHGPx-overexpressing cells as compared with the control lines of cells. Subcellular fractionation analysis showed that the amount of PHGPx associated with nuclear fractions from PHGPx-overexpressing cells was 3.5 times higher than that from the control line of cells. These results indicate that PHGPx might be involved in inactivation of 5-lipoxygenase via reductions in levels of the fatty acid hydroperoxides that are required for the full activation of 5-lipoxygenase. Thus, in addition to its role as an antioxidant enzyme, PHGPx appears to have a novel function as a modulator of the production of leukotrienes.

Animals↗
PubMed1998

Definitions of dyspepsia: time for a reappraisal.

While many definitions exist, dyspepsia is best considered a symptom complex (not a diagnosis) thought to arise in the upper gastrointestinal tract, unrelated to defecation. The symptom complex includes: upper abdominal/epigastric pain or discomfort, postprandial fullness, bloating, belching, early satiety, anorexia, nausea, retching, vomiting, heartburn and regurgitation. Patients with typical gastroesophageal reflux, biliary colic and irritable bowel syndrome should not be considered to have dyspepsia. After investigations, if a cause of dyspepsia is found, this is 'organic or structural' dyspepsia. If no structural cause is found, this is best called 'functional dyspepsia', subclassified into a) ulcer-like b) dysmotility-like c) reflux-like and d) unspecified dyspepsia. This symptom guided classification should be shifted to the first presentation with uninvestigated dyspepsia, prior to any investigations, to define a clinically useful guide to patient care. As there is considerable symptom overlap, it may be useful to combine together the ulcer and reflux-like groups into an acid-related dyspepsia group. In 1998, another approach would be to screen dyspeptic patients with an H. pylori test and classify them as H. pylori positive and negative dyspepsia.

Diagnosis, Differential↗
PubMed1998

From bench to bedside and back--report on the European Helicobacter pylori Study Group Xth International Workshop on Gastroduodenal Pathology and Helicobacter pylori.

The Xth International Workshop on Gastroduodenal Pathology and Helicobacter pylori was held in Lisbon, Portugal, from September 12 to 14, 1997. State-of-the-art reviews and research findings were presented to over 2000 participants. This review focuses on important new developments and serves as a rapid communication of clinically relevant material.

Drug Therapy, Combination↗
PubMed1998

Quality of Life in Reflux and Dyspepsia patients. Psychometric documentation of a new disease-specific questionnaire (QOLRAD).

OBJECTIVE: To develop a disease-specific QOL instrument (QOLRAD) addressing patient concerns in gastroesophageal reflux disease (GERD) and dyspepsia. Patients. 759 male (45%) and female (55%) patients with a mean age of 48.4 years (sd 15.2) were used in the psychometric evaluation. MAIN OUTCOME MEASURES: A pilot version of QOLRAD, the Gastrointestinal Symptoms Rating Scale (GSRS) and the SF-36 were completed prior to endoscopy. Items with a high ceiling effect, items measuring a different construct, i.e. with a low squared multiple correlation (R < 0.5) with the other items, items that showed redundancy by a high correlation (>0.80) with another item were removed. A confirmatory factor analysis was also performed. RESULTS: The final questionnaire included 25 items depicting problems with emotions, vitality, sleep, eating/drinking, and physical/social functioning. The internal consistency reliability was high (alpha value overall 0.97, dimensions 0.89-94). Construct validity, i.e. the associations between similar constructs in the QOLRAD, the SF-36 and the GSRS scores was confirmed. Pain and symptom severity were markers of impaired QOL. The impact on health-related QOL was similar across the functional gastrointestinal disorders with the exception of patients with a normal endoscopy, who did slightly worse. CONCLUSION: The QOLRAD is a short and user-friendly instrument with excellent psychometric properties. Its responsiveness to change in (AVMC1) clinical trials is currently being explored.

Adolescent↗