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G Tamura

Publications and source records attributed to G Tamura.

At least 37 records · Page 2Linked to original sources
PubMed2001

IL-4 differentially regulates eotaxin and MCP-4 in lung epithelium and circulating mononuclear cells.

To investigate the mechanisms of eosinophil recruitment in allergic airway inflammation, we examined the effects of interleukin (IL)-4, a Th2-type cytokine, on eotaxin and monocyte chemoattractant protein-4 (MCP-4) expression in human peripheral blood mononuclear cells (PBMCs; n = 10), in human lower airway mononuclear cells (n = 5), in the human lung epithelial cell lines A549 and BEAS-2B, and in human cultured airway epithelial cells. IL-4 inhibited eotaxin and MCP-4 mRNA expression induced by IL-1 beta and tumor necrosis factor-alpha in PBMCs but did not significantly inhibit expression in epithelial cells. Eotaxin and MCP-4 mRNA expression was not significantly induced by proinflammatory cytokines in lower airway mononuclear cells. IL-1 beta-induced eotaxin and MCP-4 protein production was also inhibited by IL-4 in PBMCs, whereas IL-4 enhanced eotaxin protein production in A549 cells. In contrast, dexamethasone inhibited eotaxin and MCP-4 expression in both PBMCs and epithelial cells. The divergent effects of IL-4 on eotaxin and MCP-4 expression between PBMCs and epithelial cells may create chemokine concentration gradients between the subepithelial layer and the capillary spaces that may promote the recruitment of eosinophils to the airway in Th2-type responses.

Blotting, Northern↗
PubMed2001

Effect of whole-body x-irradiation on antigen-induced airway response in sensitized guinea pigs.

The objectives of this study were to test the hypothesis that x-irradiation inhibits the late asthmatic response (LAR) without influencing the early asthmatic response (EAR) and to examine the mechanism of the inhibitory effect. Twenty sensitized guinea pigs were irradiated at a dose of 8 Gy. The next day, one-half of the animals were injected intravenously with spleen cells (2 x 10(8)) collected from unirradiated sensitized guinea pigs, whilst the other half were injected with vehicle only. Ten additional unirradiated sensitized guinea pigs also received vehicle only. Antigen inhalation challenge took place two days later. Pulmonary resistance was measured for 6 h after antigen exposure, and bronchoalveolar lavage and lung fixation were then undertaken. The area under the percentage pulmonary resistance curve 2-6 h after allergen inhalation was used for analysis of the LAR, while the maximal percentage change in pulmonary resistance was used for analysis of the EAR. Irradiation abolished the LAR (364.4+/-49.4 versus 62.8+/-10.4) without inhibiting the EAR (229.3+/-27.2 versus 278.7+/-40.2) and significantly inhibited the accumulation of eosinophils and lymphocytes in the airways. Transfer of spleen cells restored the LAR (334.4+/-66.8) and the recruitment of cells to the levels seen in unirradiated sensitized guinea pigs. In addition, transfer of only CD4+ T-lymphocytes separated from the spleen cells restored the LAR (439.4+/-62.1) and the cell infiltration into the airways. These inhibitory effects of x-irradiation were due to decreases in numbers of CD4+ T-lymphocytes.

Airway Resistance↗
PubMed2001

[Long-acting beta 2-stimulants].

Although inhaled salmeterol and formoterol have been clinically used as long-acting beta 2-stimulants in the world, only tulobuterol tape has been used as long-acting beta 2-stimulants in Japan. When both inhaled agents are used twice daily and the tape is done once daily, it has been reported to achieve stable bronchodilatation for 24 hours. Therefore, these agents are recognized as controllers for asthma therapy. Although tolerance of regular use of salmeterol and formoterol has been reported, it is estimated to be clinically negligible because of small degree. In this review, I described clinical usefulness of long-term treatment of asthma with tulobuterol tape.

Administration, Cutaneous↗
PubMed2000

Distinct methylation patterns of two APC gene promoters in normal and cancerous gastric epithelia.

The adenomatous polyposis coli (APC) tumor suppressor gene is mutationally inactivated in both familial and sporadic forms of colorectal cancers. In addition, hypermethylation of CpG islands in the upstream portion of APC, a potential alternative mechanism of tumor suppressor gene inactivation, has been described in colorectal cancer. Because a subset of both gastric and colorectal cancers display the CpG island methylator phenotype, we hypothesized that epigenetic inactivation of APC was likely to occur in at least some gastric cancers. APC exhibits two forms of transcripts from exons 1A and 1B in the stomach. Therefore, we investigated CpG island methylation in the sequences upstream of exons 1A and 1B, i.e., promoters 1A and 1B, respectively. We evaluated DNAs from 10 gastric cancer cell lines, 40 primary gastric cancers, and 40 matching non-cancerous gastric mucosae. Methylated alleles of promoter 1A were present in 10 (100%) of 10 gastric cancer cell lines, 33 (82.5%) of 40 primary gastric cancers, and 39 (97.5%) of 40 noncancerous gastric mucosae. In contrast, promoter 1B was unmethylated in all of these same samples. APC transcripts from exon 1A were not expressed in nine of the 10 methylated gastric cancer cell lines, whereas APC transcripts were expressed from exon 1B. Thus, expression from a given promoter correlated well with its methylation status. We conclude that in contrast to the colon, methylation of promoter 1A is a normal event in the stomach; moreover, promoter 1B is protected from methylation in the stomach and thus probably does not participate in this form of epigenetic APC inactivation.

Adolescent↗
PubMed2000

Regulation of murine airway eosinophilia and Th2 cells by antigen-conjugated CpG oligodeoxynucleotides as a novel antigen-specific immunomodulator.

The characteristic features of bronchial asthma reflect the orchestrated activity of Th2 cells. Oligodeoxynucleotides containing CpG motifs (CpG) have recently been highlighted as an immunomodulator that biases toward a Th1-dominant phenotype. We have previously reported that intratracheal coadministration of CpG and allergen inhibited airway eosinophilia and hyperresponsiveness in a synergistic manner. To substantiate the synergism between CpG and Ag, we introduced a covalently linked conjugate between CpG and Ag and examined the efficacy on airway eosinophilia and Th2 cytokine production. We found that the conjugated form of CpG plus Ag was 100-fold more efficient in regulating airway eosinophilia than the unconjugated mixture. The inhibitory effects lasted for at least 2 mo. The inhibition of airway eosinophilia by the conjugate was Ag specific and associated with an improvement of the airway hyperresponsiveness and the unresponsiveness of the Ag-specific Th2 cells in the regional lymph nodes. The CpG-Ag conjugate was 100-fold more effective than the unconjugated mixture for inducing in vitro Th1 differentiation in an IL-12-dependent manner. Our data show that CpG conjugated to Ag can work as a novel Ag-specific immunomodulator and imply that inhalation of allergen-CpG conjugate could be a desensitization therapy for patients with bronchial asthma.

Adjuvants, Immunologic↗
PubMed2000

E-Cadherin gene promoter hypermethylation in primary human gastric carcinomas.

BACKGROUND: E (epithelial)-cadherin, the cell adhesion molecule also considered a potential invasion/metastasis suppressor, is mutationally inactivated in nearly half of all undifferentiated-scattered (diffuse-type) gastric carcinomas. In addition, silencing of E-cadherin by CpG methylation within its promoter region has been reported in several gastric carcinoma cell lines. We investigated the methylation status of the E-cadherin promoter region in 53 primary human gastric carcinomas. METHODS: Hypermethylation of the E-cadherin promoter was determined by utilizing methylation-specific polymerase chain reaction (PCR)-single-strand conformation polymorphism (MSP-SSCP) analysis followed by direct sequencing of PCR products. Expression of E-cadherin was studied by western blot analysis. All statistical tests were two-sided. RESULTS: Hypermethylation of the E-cadherin promoter was evident in 27 (51%) of 53 primary gastric carcinomas examined by MSP-SSCP. It occurred more frequently in carcinomas of the undifferentiated-scattered type (in 15 [83%] of 18) than in other histologic subtypes (in 12 [34%] of 35) (P =.0011, Fisher's exact test), and it was present at similar rates in early (in six [60%] of 10) versus advanced (in 21 [49%] of 43) carcinomas (P =.73, Fisher's exact test). Methylation occurring at all cytosine-guanosine sequences (CpGs) near the transcriptional start site was confirmed in six of six tumors examined by bisulfite-DNA sequencing, including two early gastric carcinomas. In addition, loss or diminished expression of E-cadherin was confirmed by western blotting in four of the six tumor tissues demonstrating hypermethylation. CONCLUSIONS: The E-cadherin promoter frequently undergoes hypermethylation in human gastric cancers, particularly those of the undifferentiated-scattered histologic subtype. E-cadherin promoter hypermethylation is associated with decreased expression and may occur early in gastric carcinogenesis.

Blotting, Western↗
PubMed2000

Cellular phenotypes of differentiated-type adenocarcinomas and precancerous lesions of the stomach are dependent on the genetic pathways.

To elucidate the relationship between genetic alterations and cellular phenotypes in differentiated-type carcinomas and precancerous lesions of the stomach, mutations of p53, APC and K-ras genes were examined, as well as microsatellite instability (MSI), in 52 tumours of the stomach. Tumours were selected with the following phenotypical features, using mucin histochemical and immunohistochemical analyses, in addition to their morphological features: (1) tumours with an extremely well-preserved gastric foveolar phenotype (foveolar-type); (2) tumours with an extremely well-preserved complete-type intestinal metaplastic phenotype (CIM-type); and (3) ordinary tumours without extreme phenotypes (ordinary-type). MSI occurred in 45% of foveolar-type, 24% of ordinary-type, and 0% of CIM-type tumours. p53 gene alterations occurred in 5% of foveolar-type, 18% of ordinary-type, and 31% of CIM-type. APC gene alterations were detected in 9% of foveolar-type, 6% of ordinary-type, and 0% of CIM-type. No K-ras gene mutation was detected in any of the three types. These results indicate that the genetic pathways are quite different among the phenotypes of tumours of the stomach. The 'mutator pathway', characterized by MSI, plays an important role in the tumourigenesis of foveolar-type, but not CIM-type tumours. The 'suppressor pathway', represented by p53 alteration, could participate in the tumourigenesis of the CIM-type, but is rare in foveolar-type tumours.

Adenocarcinoma↗
PubMed2000

Author's reply

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Journal Article↗
PubMed2000

Frequent hypermethylation of the hMLH1 gene promoter in differentiated-type tumors of the stomach with the gastric foveolar phenotype.

Hypermethylation of the hMLH1 mismatch repair gene promoter has been revealed to lead to microsatellite instability (MSI). Previously, we demonstrated a high prevalence of MSI in differentiated-type gastric tumors showing distinct features of gastric foveolar epithelium (foveolar type). To clarify the significance of hMLH1 promoter hypermethylation in the development of this tumor type, we studied promoter methylation status and expression of hMLH1 in foveolar-type tumors and their surrounding non-neoplastic mucosae, as well as in tumors with other cellular phenotypes. The results were compared to MSI status. After phenotypical analyses using mucin histochemistry and immunohistochemistry, 41 differentiated-type tumors with distinct cellular phenotypes were classified into three categories: foveolar type, intestinal type (tumors with the distinct cellular phenotype of the intestine), and combined type (tumors with both foveolar and intestinal phenotypes). Methylation-specific polymerase chain reaction (MSP) was performed to determine the methylation status of hMLH1 promoter. hMLH1 protein expression was immunohistochemically examined. MSI was detected in 57% of the foveolar type, 8% of the intestinal type, and 67% of the combined-type tumors. Hypermethylation of hMLH1 promoter was found in 74% of the foveolar type, 33% of the intestinal type, and 83% of the combined-type tumors. Of 18 MSI-positive tumors, all but one were hypermethylated. Methylation status of hMLH1 promoter correlated well with protein expression in foveolar-type tumors. Moreover, hypermethylation was also detected frequently (71%) in the non-neoplastic surrounding mucosa of the hypermethylated tumors. Hypermethylation of hMLH1 promoter is an initial, vital event in the development of foveolar-type tumors of the stomach.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Microsatellite alterations in differentiated-type adenocarcinomas and precancerous lesions of the stomach with special reference to cellular phenotype.

To elucidate the relationship between genetic alterations and cellular phenotype of differentiated-type adenocarcinomas and precancerous lesions of the stomach, we phenotyped 61 gastric tumors consisting of 33 noninvasive lesions and 28 submucosal invasive carcinomas by histochemical and immunohistochemical techniques, including analysis of mucin expression. We then analyzed loss of heterozygosity (LOH) at tumor suppressor loci, examined microsatellite instability (MSI), and compared the results according to cellular phenotype. Of the 61 gastric tumors studied, 7% (4 of 61) were classified as tumors with a gastric foveolar epithelial phenotype (foveolar-type), 8% (5 of 61) as tumors with a complete-type intestinal metaplastic phenotype (CIM-type), and the remaining 85% (52 of 61) as tumors with an ordinary phenotype (ordinary-type). Forty-two percent (26 of 61) of the tumors showed LOH on at least 1 chromosomal arm. Although LOH was rare in foveolar-type tumors, it was present at variable frequencies at each tumor suppressor loci in tumors with other cellular phenotypes. p53 overexpression was observed in 0% (0 of 4) of foveolar-type, 48% (25 of 52) of ordinary-type, and 80% (4 of 5) of CIM-type tumors. With regard to MSI, all (4 of 4) of the foveolar-type tumors were classified as having high-rate MSI (MSI-H), whereas all (5 of 5) of the CIM-type tumors were microsatellite stable (MSS). Of 52 ordinary-type tumors, 19% (10 of 52) were classified as MSI-H, 12% (6 of 52) as low-rate MSI (MSI-L), and 69% (36 of 52) as MSS. The incidence of MSI-H was found to be significantly higher in foveolar-type tumors (100%; 4 of 4) than in ordinary-type (19%; 10 of 52) or CIM-type tumors (0%; 0 of 5) (P < .01). An inverse correlation between MSI-H and p53 overexpression was also noticed (P < .01). Results suggested that each cellular phenotype followed a different genetic pathway; foveolar-type tumors followed the "mutator" pathway, characterized by MSI, CIM-type tumors followed the "suppressor" pathway, characterized by LOH of tumor suppressor loci and p53 overexpression, and ordinary-type tumors appeared to show mixed genetic alterations of both types.

Adenocarcinoma↗
PubMed2000

IL-1beta induces eotaxin gene transcription in A549 airway epithelial cells through NF-kappaB.

Eotaxin is an asthma-related C-C chemokine that is produced in response to interleukin-1beta (IL-1beta). We detected an increase in newly transcribed eotaxin mRNA in IL-1beta-stimulated airway epithelial cells. Transient transfection assays using promoter-reporter constructs identified a region as essential for IL-1beta-induced increases in eotaxin transcription. Using site-directed mutagenesis, we found that a nuclear factor-kappaB (NF-kappaB) site located 46 bp upstream from the transcriptional start site was both necessary and sufficient for IL-1beta induction of reporter construct activity. Electrophoretic mobility shift assay demonstrated that IL-1beta-stimulated airway epithelial cells produced p50 and p65 protein that bound this site in a sequence-specific manner. The functional importance of the NF-kappaB site was demonstrated by coexpression experiments in which increasing doses of p65 expression vector were directly associated with reporter activity exclusively in constructs with an intact NF-kappaB site (r(2) = 0.97, P = 0.002). Moreover, IL-1beta-induced increases in eotaxin mRNA expression are inhibited by inhibitors of NF-kappaB. Our findings implicate NF-kappaB and its binding sequence in IL-1beta-induced transcriptional activation of the eotaxin gene.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed2000

Regulation of T-helper type 2 cell and airway eosinophilia by transmucosal coadministration of antigen and oligodeoxynucleotides containing CpG motifs.

The characteristic features of bronchial asthma, including airway eosinophilia and elevated immunoglobulin (Ig)E levels, are known to be orchestrated by T-helper (Th) 2 cells. Oligodeoxynucleotides containing CpG motifs (CpG) have recently been highlighted as an immunomodulator that biases toward a Th1-dominant phenotype. However, CpG may incur nonspecific Th1 activation and toxic effects. In this study we report a novel inhibition of Th2 cells by transmucosal inoculation of antigen and CpG. Intratracheal instillation of CpG inhibited airway eosinophilia and Th2 cytokine production in antigen-sensitized mice. The inhibition was observed when CpG was given at the same time or in advance of antigen challenge. Notably, concomitant administration of CpG and antigen (as opposed to either one alone) was essential for the inhibitory effects. The antigen dose could be minimized to avoid a harmful boost of eosinophilia. CpG had few effects on systemic anti-ovalbumin IgE responses. These results demonstrate that a synergism between transmucosally administered allergen and CpG inhibits Th2 cells in parallel with an improvement in airway eosinophilia and hyperresponsiveness without impeding systemic immune responses. Our data imply that inhalation of a minimal amount of allergen plus CpG could be a novel desensitization therapy for patients with bronchial asthma.

Animals↗
PubMed2000

A novel function of thyrotropin as a potentiator of electrolyte secretion from the tracheal gland.

Accumulating evidence suggests that thyrotropin (thyroid-stimulating hormone [TSH]) plays some roles in immunoregulation by an extrathyroidal action. Because airway submucosal glands are responsible for nonspecific and specific airway defense, we tested the effect of TSH on feline tracheal submucosal gland using a whole-cell patch-clamp technique, immunohistochemistry, and reverse transcription/polymerase chain reaction (RT-PCR). TSH potentiated neurotransmitter-induced ionic currents significantly in a dose-dependent manner. Acetylcholine (10(-)(8) M)- and norepinephrine (10(-)(7) M)-induced inward current (I(i)), which we previously showed to be a Cl(-) current, were increased to about 3-fold the pre-TSH control responses, respectively, by 2.0 ng/ml TSH; and to 6- and 23-fold the control values by 20.0 ng/ml TSH, respectively. TSH alone was without effect up to 20.0 ng/ml. Follicular stimulating hormone only slightly affected the I(i) (1. 5-fold the control). Analyses with immunohistochemistry and RT-PCR failed to identify TSH receptors on the glandular tissue. Maneuvers to raise the cellular adenosine 3',5'-cyclic monophosphate also failed to mimic the TSH-mediated potentiation. The TSH effect appeared to be mediated by a signaling pathway involving tyrosine kinase because its inhibitors (genistein and herbimycin A) abolished the augmentation completely, and interferon-gamma, a tyrosine kinase activator, imitated the TSH action on submucosal gland. Thus, TSH may be an important regulator of airway fluid secretion.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Activation and transforming growth factor-beta production in eosinophils by hyaluronan.

To investigate whether extracellular matrix glycosaminoglycan hyaluronan (HA) modulates eosinophil activation and transforming growth factor (TGF)-beta production by eosinophils, human peripheral blood eosinophils (purity > 99%) from 12 patients with mild to moderate asthma or six healthy subjects were isolated and incubated with increasing concentrations of low molecular weight (mol wt) HA ( approximately 0.2 x 10(6) D) or high mol wt HA (3.0 to approximately 5.8 x 10(6) D). We found that the low mol wt HA has a pronounced effect on eosinophil survival in both patients with asthma and healthy subjects in a dose-dependent fashion on Days 2 and 4. Whereas the high mol wt HA had a smaller effect on eosinophil survival than did the low mol wt HA. The HA-mediated eosinophil survival was partially but significantly inhibited ( approximately 50% inhibition) by a blocking monoclonal antibody for CD44, a specific receptor of HA, and largely inhibited by an anti-granulocyte macrophage colony-stimulating factor (GM-CSF) neutralizing antibody but not by an anti-interleukin (IL)-3 or anti-IL-5 neutralizing antibody. In addition, the low mol wt HA increased GM-CSF messenger RNA (mRNA) expression and protein secretion by eosinophils in a dose-dependent fashion, suggesting that the HA-mediated eosinophil survival is due mainly to induction of GM-CSF release through partial CD44 signaling. Furthermore, we demonstrated that the low mol wt HA results in morphologic changes in eosinophils such as transforming from a round to a spindle shape and in homotypic aggregation, upregulates intercellular adhesion molecule-1 expression, and increases TGF-beta mRNA expression and protein secretion by eosinophils. These observations suggest previously unforeseen interactions between eosinophils and low mol wt extracellular matrix and, thus, novel pathways by which eosinophils may contribute to the regulation of airway inflammation and airway remodeling.

Asthma↗
PubMed2000

[Theophylline].

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Asthma↗
PubMed1999

Hypermethylation of the hMLH1 gene promoter in human gastric cancers with microsatellite instability.

Human gastric carcinoma shows a higher prevalence of microsatellite instability (MSI) than does any other type of sporadic human cancer. The reasons for this high frequency of MSI are not yet known. In contrast to endometrial and colorectal carcinoma, mutations of the DNA mismatch repair (MMR) genes hMLH1 or hMSH2 have not been described in gastric carcinoma. However, hypermethylation of the hMLH1 MMR gene promoter is quite common in MSI-positive endometrial and colorectal cancers. This hypermethylation has been associated with hMLH1 transcriptional blockade, which is reversible with demethylation, suggesting that an epigenetic mechanism underlies hMLH1 gene inactivation and MMR deficiency. Therefore, we studied the prevalence of hMLH1 promoter hypermethylation in a total of 65 gastric tumors: 18 with frequent MSI (MSI-H), 8 with infrequent MSI (MSI-L), and 39 that were MSI negative. We found a striking association between hMLH1 promoter hypermethylation and MSI; of 18 MSI-H tumors, 14 (77.8%) showed hypermethylation, whereas 6 of 8 MSI-L tumors (75%) were hypermethylated at hMLH1. In contrast, only 1 of 39 (2.6%) MSI-negative tumors demonstrated hMLH1 hypermethylation (P<0.0001 for MSI-H or MSI-L versus MSI-negative). Moreover, hypermethylated cancers demonstrated diminished expression of hMLH1 protein by both immunohistochemistry and Western blotting, whereas nonhypermethylated tumors expressed abundant hMLH1 protein. These data indicate that hypermethylation of hMLH1 is strongly associated with MSI in gastric cancers and suggest an epigenetic mechanism by which defective MMR occurs in this group of cancers.

Adaptor Proteins, Signal Transducing↗
PubMed1999

The common 18-base pair deletion at codons 418-423 of the E-cadherin gene in differentiated-type adenocarcinomas and intramucosal precancerous lesions of the stomach with the features of gastric foveolar epithelium.

Alterations of the E (epithelial)-cadherin gene are often involved in undifferentiated-type carcinomas of the stomach, but not in the differentiated type. Recently, it was recognized that certain differentiated-type carcinomas possess the features of gastric foveolar epithelium. Such carcinomas are closely linked with undifferentiated-type carcinomas. Nineteen lesions (ten differentiated-type carcinomas and nine precancerous lesions) with a predominant gastric foveolar phenotype, as determined not only by mucin histochemistry and immunohistochemistry but also by morphology, were analysed for mutations of the E-cadherin gene using the nested polymerase chain reaction single-strand conformation polymorphism method. E-cadherin gene mutation was detected in 4 of 19 lesions (21 per cent) (three precancerous and one cancerous). Sequencing revealed an 18 bp deletion corresponding to codons 418-423 of exon 9 common to all four lesions. This mutation was previously reported in an advanced carcinoma of undifferentiated type. The results suggest that these tumours progress to undifferentiated-type carcinomas through loss of E-cadherin function.

Adenocarcinoma↗