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Biomedical subjects

A Ishiguro

Publications and source records attributed to A Ishiguro.

At least 19 recordsLinked to original sources
PubMed2001

An increase in circulating mast cell colony-forming cells in asthma.

We compared a potential to generate mast cells among various sources of CD34(+) peripheral blood (PB) cells in the presence of stem cell factor (SCF) with or without thrombopoietin (TPO), using a serum-deprived liquid culture system. From the time course of relative numbers of tryptase-positive and chymase-positive cells in the cultured cells grown by CD34(+) PB cells of nonasthmatic healthy individuals treated with G-CSF, TPO appears to potentiate the SCF-dependent growth of mast cells without influencing the differentiation into mast cell lineage. CD34(+) PB cells from asthmatic patients in a stable condition generated significantly more mast cells under stimulation with SCF alone or SCF+TPO at 6 wk of culture than did steady-state CD34(+) PB cells of normal controls. Single-cell culture studies showed a substantial difference in the number of SCF-responsive or SCF+TPO-responsive mast cell progenitors in CD34(+) PB cells between the two groups. In the presence of TPO, CD34(+) PB cells from asthmatic children could respond to a suboptimal concentration of SCF to a greater extent, compared with the values obtained by those of normal controls. Six-week cultured mast cells of asthmatic subjects had maturation properties (intracellular histamine content and tryptase/chymase enzymatic activities) similar to those derived from mobilized CD34(+) PB cells of nonasthmatic subjects. An increase in a potential of circulating hemopoietic progenitors to differentiate into mast cell lineage may contribute to the recruitment of mast cells toward sites of asthmatic mucosal inflammation.

Adolescent↗
PubMed2001

Antioxidant activities of buckwheat hull extract toward various oxidative stress in vitro and in vivo.

We have undertaken four basic in vitro studies and an animal experiment to obtain information about the antioxidant activities of buckwheat hull extract (BWHE). In the in vitro studies, BWHE scavenged super oxide anion produced in the xanthine/xanthine oxidase system (IC50=11.4 microg phenolic compound/ml), and strongly inhibited autoxidation of linoleic acid (IC50=6.2 microg phenolic compound/ml). Low-density lipoprotein (LDL) oxidation induced by Cu2+ ion was also protected by BWHE. In the animal experiment, ddY mice were fed a standard diet supplemented with 0.75% BWHE for 14 d. In blood, liver and brain of the mice TBARS and fluorescent substance concentration were significantly decreased compared with those of non-treated mice. SOD like activity in serum also significantly rose by BWHE treatment. BWHE was shown to be effective for protecting biological systems against various oxidative stresses in vitro, and to have antioxidant activity in vivo.

Animals↗
PubMed2000

Stressful delivery influences circulating thrombopoietin (TPO) levels in newborns: possible role for cortisol in TPO-mpl binding.

The regulation mechanism of circulating thrombopoietin (TPO) level in human newborns remains unknown. In the present study, we examined whether the TPO concentrations in cord blood were influenced by the difference in the delivery method and the presence or absence of maternal/fetal complications. Cortisol levels were simultaneously measured to assess the adrenal response of fetuses. Both the TPO level and the cortisol level were substantially greater in the neonates delivered vaginally with and without the complications than in those delivered by cesarean section without the complications. The binding assay showed that the incubation of mpl(+)/BaF3 cells with cortisol gave rise to a significant decrease in the binding sites of TPO. These results suggest that the stress to the fetuses near the time of delivery affects the cord blood TPO levels, which may be mediated in part by the action of cortisol on the TPO-mpl binding system.

Binding Sites↗
PubMed2000

Isolation and characterization of a major antigenic component of Malassezia globosa to IgE antibodies in sera of patients with atopic dermatitis.

Three major components of Malassezia globosa were isolated from 2-ME extracts of this fungus by ion-exchange column chromatography and are referred to as Malg46a, Malg46b and Malg67, respectively. IgE antibodies to these components in the sera of patients with AD were detected by immunoblots. In Western blot, IgE antibodies to Malg46b were most frequently detected in the sera of AD patients. Dot blot with the Malg46b-containing fraction immunologically reacted with 69% of the sera of the patients, and with 83% of the sera of the patients who were positive for IgE antibodies to the 2-ME extract of M. globosa in the Western blot. The intensities generated for each dot correlated well with the total intensities generated for the 2-ME extract of M. globosa in the Western blot (r=0.763). In the lectin blot, Con A reacted with both Malg46a and Malg46b but not with Malg67. The polyclonal antibody to Malg46b reacted strongly only with the 2-ME extract of M. globosa and reacted slightly with M. restricta. In conclusion, a glycoprotein, Malg46b of M. globosa, is dominantly expressed in this fungus and is a possible major antigen for IgE antibodies in patients with AD.

Antigens, Fungal↗
PubMed2000

The Rpb6 subunit of fission yeast RNA polymerase II is a contact target of the transcription elongation factor TFIIS.

The Rpb6 subunit of RNA polymerase II is one of the five subunits common to three forms of eukaryotic RNA polymerase. Deletion and truncation analyses of the rpb6 gene in the fission yeast Schizosaccharomyces pombe indicated that Rpb6, consisting of 142 amino acid residues, is an essential protein for cell viability, and the essential region is located in the C-terminal half between residues 61 and 139. After random mutagenesis, a total of 14 temperature-sensitive mutants were isolated, each carrying a single (or double in three cases and triple in one) mutation. Four mutants each carrying a single mutation in the essential region were sensitive to 6-azauracil (6AU), which inhibits transcription elongation by depleting the intracellular pool of GTP and UTP. Both 6AU sensitivity and temperature-sensitive phenotypes of these rpb6 mutants were suppressed by overexpression of TFIIS, a transcription elongation factor. In agreement with the genetic studies, the mutant RNA polymerases containing the mutant Rpb6 subunits showed reduced affinity for TFIIS, as measured by a pull-down assay of TFIIS-RNA polymerase II complexes using a fusion form of TFIIS with glutathione S-transferase. Moreover, the direct interaction between TFIIS and RNA polymerase II was competed by the addition of Rpb6. Taken together, the results lead us to propose that Rpb6 plays a role in the interaction between RNA polymerase II and the transcription elongation factor TFIIS.

Amino Acid Sequence↗
PubMed1999

Carbamazepine-induced thrombocytopenia defined by a challenge test.

Carbamazepine (CBZ), a widely used anticonvulsant, occasionally causes serious hematologic disorders. A 12-year-old boy was admitted because of a diffuse petechial rash and profound thrombocytopenia (10 x 10(9) platelets/l), after having been treated for epilepsy with CBZ for 12 days. Seven days following withdrawal of CBZ and initiation of prednisolone therapy, the platelet count recovered. In a subsequent challenge test with CBZ, platelet counts again decreased, and the levels of platelet-associated IgG and serum interleukin-6 increased. No antibodies against platelet glycoprotein IIb/IIIa or Ib were detected in plasma. We believe that this is the first reported occasion when CBZ-induced thrombocytopenia has been defined by a rechallenge test.

Anticonvulsants↗
PubMed1999

Age-related changes in thrombopoietin in children: reference interval for serum thrombopoietin levels.

We studied thrombopoietin (TPO, Mpl ligand) values using a sensitive ELISA in 254 serum samples obtained from disease-free children and adult volunteers. TPO was detected in all samples, and its values ranged widely from 0.25 to 9.18 fmol/ml. When analysed by dividing the subjects into 11 age groups, the mean TPO levels from birth to 1 month of age were increased (3.73-5.92 fmol/ml). The highest values were found 2 d after birth; TPO levels then gradually decreased to adult levels (0.83 fmol/ml). The relationship between TPO values and platelet counts was not significant in all subjects (r = 0.27) or in children alone (r = 0.12). In children > 1 month of age a 95% reference interval for serum TPO values was determined from 0.58 to 3.27 fmol/ml. A significant correlation was found between TPO values in serum and plasma; serum TPO values = -0.257 + 4.039 x plasma TPO values (r = 0.951, P < 0.001, n = 22). This study is the first to report age-dependent changes in blood TPO levels throughout child development. Serum TPO values were significantly high up to 1 month of age and were correlated with plasma TPO levels.

Adolescent↗
PubMed1999

Correlation of lifting versus non-lifting and microscopic depth of invasion in early colorectal cancer.

BACKGROUND: The non-lifting sign is considered a contraindication to endoscopic resection. Our objective was to investigate whether lifting or nonlifting of a lesion is determined by the volume of normal submucosal tissue. METHODS: We measured the thickness of the submucosa and examined the relation between submucosal invasion and lesion elevation induced by submucosal injection in 60 patients with colorectal cancer with evidence of submucosal invasion. Extent of tumor elevation was classified into two groups: A, lifting; B, non-lifting. Submucosal invasion was classified as sm1, sm2, or sm3. The distance between the carcinoma and the line of resection and that between the carcinoma and the muscularis propria were measured. RESULTS: Of 31 sm1 lesions, 29 (93.5%) were group A. All 6 sm3 lesions were group B. All lesions in group A had a value for the distance between carcinoma and muscularis propria of more than 1000 microm. Group B lesions with sm3 invasion had distances of only 105 to 750 microm. CONCLUSION: Lesions classified as sm3 do not elevate in response to submucosal injection, and lesions that become elevated on injection can be resected endoscopically because they are sm1 or sm2 and have a thickness of normal submucosa of more than 1000 microm.

Adenomatous Polyps↗
PubMed1999

Serum granulocyte colony-stimulating factor levels in patients with chronic neutropenia of childhood: modulation of G-CSF levels by myeloid precursor cell mass.

The serum G-CSF levels of eight patients with severe congenital neutropenia (SCN) were found to be significantly higher than those of 22 patients with chronic benign neutropenia (CBN). The relative number of cells expressing the G-CSF receptor in light density bone marrow cells (LDBMC) was lower in patients with SCN than in patients with CBN or in normal subjects. When recombinant human G-CSF was incubated with LDBMC, G-CSF levels were decreased by LDBMC from normal subjects and CBN patients, but not by those from SCN patients. Serum G-CSF concentrations, which are affected by mature neutrophils, may also be modulated by myeloid precursor cells in the bone marrow.

Adolescent↗
PubMed1998

Two large subunits of the fission yeast RNA polymerase II provide platforms for the assembly of small subunits.

The subunit-subunit contact network was analyzed for the Schizosaccharomyces pombe RNA polymerase II consisting of ten putative subunits. Previously we carried out far-Western blot analysis of bimolecular interaction with radio-labeled subunit 3 and 5 probes. Here we extended the analysis using another six small-sized subunits as probes. Taking the results together the subunit-subunit interaction was observed for a total 18 (or 19) combinations. All eight small-sized subunits exhibited binding activities to two large subunits, Rpb1 and Rpb2. In addition, bimolecular interaction was observed for the combinations of Rpb3-Rpb5, Rpb3-Rpb11 (and Rpb5-Rpb8/11). The subunit-subunit contact within the assembled RNA polymerase was then analyzed by protein-protein cross-linking using five species of bifunctional cross-linkers with different length and specificity. Cross-linking was observed for a total of 19 combinations, including five combinations between small subunits, Rpb3-Rpb10, Rpb3-Rpb11, Rpb5-Rpb6, Rpb6-Rpb7 and Rpb6-Rpb8. The results altogether indicate that two large subunits Rpb1 and Rpb2 provide the platform for assembly of small subunits and also small subunits interact with each other for limited combinations. Direct contact of the two large subunits, Rpb1 and Rpb2, was also demonstrated by cross-linking.

Cross-Linking Reagents↗
PubMed1998

Location of subunit-subunit contact sites on RNA polymerase II subunit 3 from the fission yeast Schizosaccharomyces pombe.

RNA polymerase II from the fission yeast Schizosaccharomyces pombe consists of 10 putative subunits. Subunit 3 (Rpb3) is a homologue of prokaryotic alpha subunit, which plays a key role in the assembly of core enzyme subunits. Previously we indicated that Rpb3 also plays an essential role in subunit assembly because it interacts with at least four subunits, two large subunits (Rpb1 and Rpb2) and two medium-sized subunits (Rpb3 and Rpb5) (1), and it constitutes a core subassembly consisting of Rpb2, Rpb3, and Rpb11 (2). Using a synthetic mixture of equimolar amounts of individual subunits, which were all purified from cDNA-expressed Escherichia coli, we found here that Rpb3 also interacts with Rpb11, another alpha homologue. By making a set of Rpb3 deletion derivatives, we carried out mapping of the Rpb5- and Rpb11-contact sites on Rpb3. By far-Western blot and GST pull-down assays, we found that the amino acid sequence between residues 105-263 of Rpb3 is involved in binding Rpb5, and the sequence between residues 105-297 is required for binding Rpb11. Although the Rpb5- and Rpb11-contact sites on Rpb3 overlap each other, both subunits are able to associate with Rpb3 simultaneously. The binding of Rpb5 stabilizes the Rpb3-Rpb11 heterodimer.

Binding Sites↗
PubMed1998

Viability and pathogenicity of intersubgroup viroid chimeras suggest possible involvement of the terminal right region in replication.

To investigate the structural determinants regulating viroid replication and pathogenicity, we have examined the biological properties of four chimeric viroids containing sequences derived from hop stunt (HSVd) and citrus exocortis (CEVd) viroids. The viability of each chimera--CEHS (CEVd left half + HSVd right half), HSCE (HSVd left half + CEVd right half), CE/HS-TR (CEVd + HSVd right terminal loop), and HS/CE-TR (HSVd + CEVd right terminal loop)--was tested by inoculation onto cucumber and tomato seedlings. Chimeras CEHS and HSCE were not infectious, but CE/HS-TR and HS/CE-TR replicated stably and produced disease symptoms when inoculated onto tomato or cucumber, respectively. Progeny accumulation was reduced 10-fold or more compared to that of CEVd in tomato or HSVd in cucumber. The results suggested that the TR, like the TL and P regions, forms a relatively independent structural unit that contributes to the total function of a viroid. The effect of sequences in the right terminal loop on pathogenicity appears to be indirect, modulating the efficiency of viroid replication (or accumulation) efficiency rather than symptom expression per se.

Chimera↗