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Biomedical subjects

A Tachibana

Publications and source records attributed to A Tachibana.

At least 37 records · Page 2Linked to original sources
PubMed2000

Expression of T-cadherin (CDH13, H-Cadherin) in human brain and its characteristics as a negative growth regulator of epidermal growth factor in neuroblastoma cells.

In the present study, we first examined the expression of T-cadherin in human CNS by northern blot analysis, immunohistochemical staining, and in situ hybridization. Northern blot analysis demonstrated expression of T-cadherin in human adult cerebral cortex, medulla, thalamus, and midbrain. Immunohistochemical staining with a newly generated monoclonal antibody, designated MA-511, revealed strong expression of T-cadherin in neural cell surface membrane and neurites in adult cerebral cortex, medulla oblongata, and nucleus olivaris. Little or no expression of T-cadherin was found in spinal cord. We further examined T-cadherin expression in various developing nervous systems, and found that T-cadherin expression was lower in developing brain than in adult brain. In situ hybridization revealed that neural cells in medulla oblongata and nucleus olivaris, but not in spinal cord, possessed T-cadherin molecules. We transfected T-cadherin-negative TGW and NH-12 neuroblastoma cells with a T-cadherin cDNA-containing expression vector. T-cadherin-expressing neuroblastoma cells lost mitogenic proliferative response to epidermal growth factor. Epidermal growth factor is known to be required for proliferation of neural stem cells. This finding, together with those of the present study, suggests that T-cadherin functions as a negative regulator of neural cell growth.

Adult↗
PubMed2000

WAF1 accumulation by carbon-ion beam and alpha-particle irradiation in human glioblastoma cultured cells.

PURPOSE: There have been no reports about the effects of heavy-ion beams on the expression of the WAF1 gene, although ionizing radiation such as y-rays and X-rays is well known to induce WAF1 (p21/CIP1/sdi1) gene expression in a p53-dependent manner. In the present study, it was examined whether WAF1 accumulation was induced after carbon-ion (C-) beam or alpha-particle irradiation in four glioblastoma cell lines. MATERIALS AND METHODS: A colony assay for radiosensitivity and Western blot analysis of WAF1 were applied to two human glioblastoma cell lines, A-172 bearing wild-type p53 (wtp53) and T98G bearing mutated p53 (mp53). A-172/neo and A-172/mp53 were transfected with a control vector (containing only a neo selection marker) and a mp53 expression vector respectively. RESULTS: The amount of WAF1 increased markedly after X-ray irradiation in A-172 and A-172/neo cells but not in T98G and A-172/mp53 cells. The level of WAF1 reached a plateau at 3-10 h after X-ray irradiation at 5 Gy in A-172 and A-172/neo cells. Likewise, the levels of WAF1 in A-172 and A-172/neo cells reached a plateau at 3-10 h and 6-24 h after C-beam (3.0 Gy) and alpha-particle (4.5 Gy) irradiation respectively. The amount of WAF1 increased markedly in a dose-dependent manner 10 h after X-ray, C-beam or alpha-particle irradiation in A-172 and A-172/neo cells but not in T98G or A-172/mp53 cells. In addition, cell survival assay showed that these cell lines were most sensitive to C-beams, less sensitive to alpha-particles and least sensitive to X-rays at 10% survival. There was no difference in sensitivity among these cell lines against C-beam and alpha-particle irradiation whereas wtp53 cells (A-172 and A-172/neo) were more sensitive to X-rays than mp53 cells (A-172/mp53 and T98G). CONCLUSIONS: These results indicate that C-beams and alpha-particles induce p53-dependent WAF1 accumulation as well as is the case with X-rays, suggesting that WAF1 protein accumulation may not contribute to cell killing.

Alpha Particles↗
PubMed2000

Stimulation of the beta(2) integrin, alpha(M)beta(2), triggers tyrosine phosphorylation and cellular degranulation on human eosinophils.

Activation of human eosinophils by specific extracellular stimuli triggers the cellular degranulation response. Because cellular adhesion is critical for this eosinophil degranulation, we have tested the hypothesis that ligation of the beta(2) integrin, alpha(M)beta(2) (Mac-1, CD11b/CD18), leads to intracellular signaling events that contribute to the eosinophil activation response. Recently, we found that engagement of beta(2) integrin using two different approaches, such as cell adhesion induced by IL-5 or direct ligation of alpha(M)beta(2), triggered tyrosine phosphorylation of Cbl, the product of the c-cbl proto-oncogene, paxillin, a cytoskeletal protein, an unidentified 115-kD protein, and subsequent cellular degranulation. The results of this study indicate that engagement of alpha(M)beta(2) on eosinophils triggers an intracellular signaling cascade leading to cellular degranulation. Tyrosine phosphorylation of Cbl, paxillin, and a 115-kD protein may play important roles in adhesion-dependent cellular functions of eosinophils.

CD18 Antigens↗
PubMed2000

[Fibrosing alveolitis following Legionella pneumonia].

We reported a case of fibrosing alveolitis following Legionella pneumonia. A 62-year-old man was admitted to our hospital with fever after a visit to a hot spring. Chest X-ray films on admission demonstrated air-space consolidation in the right lower lung. Legionella pneumonia was diagnosed because the patient had elevated serum antibody to Legionella pneumophila serogroup Ia and tested positive for urinary antigen. Although he was initially treated with rifampicin and erythromycin, he experienced drug-induced eruptions. Antibiotic therapy was accordingly changed to clarithromycin, levofloxacin, and minocycline, which together alleviated the patient's clinical symptoms but delayed radiologic regression. Chest X-ray films 2 months after the onset of illness revealed diffuse ground-glass opacities and progressive reduction of volume in the right lung. Long-term corticosteroid treatment was required. Three and half months after disease onset, fever recurred with the appearance of interstitial shadows in the left lung and positive tests for urinary antigen. Increasing the corticosteroid dose resolved the patient's symptoms.

Anti-Inflammatory Agents↗
PubMed1999

Roles of dopamine and serotonin in larval attachment of the barnacle, Balanus amphitrite.

In order to clarify the roles of neurotransmitters including serotonin and dopamine in larval settlement (attachment) and metamorphosis of the barnacle Balanus amphitrite, the effects of lisuride, which acts as both a serotonin agonist/antagonist and a dopamine agonist, were examined. Lisuride did not induce larval attachment and metamorphosis; however, it promoted only larval behavior of searching for attachment sites without actual attachment to substrata which lasted for 5 to 6 days in a dose-dependent manner. Further evidence was obtained with a range of agonists/antagonists; serotonin agonists promoted the attachment, while serotonin antagonists inhibited it. Similarly, dopamine agonists inhibited the attachment. Furthermore, mixtures of serotonin and dopamine showed similar effects to those of lisuride. These results suggested that the promotion effect on larval searching behavior was derived from a combination of activities of serotonin and dopamine. Moreover, both serotonin and dopamine were detected in cyprids by HPLC. Thus, larval attachment process is regulated by both serotonin and dopamine neurons in this species. J. Exp. Zool. 284:746-758, 1999. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗
PubMed1999

Coordinated regulation of radioadaptive response by protein kinase C and p38 mitogen-activated protein kinase.

Eukaryotic cells are known to have an inducible or adaptive response that enhances radioresistance after a low priming dose of radiation. This radioadaptive response seems to present a novel cellular defense mechanism. However, its molecular processing and signaling mechanisms are largely unknown. Here, we studied the role of protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) in the expression of radioadaptive response in cultured mouse cells. Protein immunoblot analysis using isoform-specific antibodies showed an immediate activation of PKC-alpha upon X-irradiation as indicated by a translocation from cytosol to membrane. A low priming dose caused a prolonged translocation, while a nonadaptive high dose dramatically downregulated the total PKC level. Low-dose X-rays also activated the p38 MAPK. The activation of p38 MAPK and resistance to chromosome aberration formation were blocked by SB203580, an inhibitor of p38 MAPK, and Calphostin C, an inhibitor of PKC. Furthermore, it was demonstrated that p38 MAPK was physically associated with delta1 isoform of phospholipase C (PLC-delta1), which hydrolyzed phosphatidylinositol bisphosphate into diacylglycerol, an activator of PKC, and that SB203580 also blocked the activation of PKC-alpha. These results indicate the presence of a novel mechanism for coordinated regulation of adaptive response to low-dose X-rays by a nexus of PKC-alpha/p38 MAPK/PLC-delta1 circuitry feedback signaling pathway with its breakage operated by downregulation of labile PKC-alpha at high doses or excess stimuli.

Adaptation, Biological↗
PubMed1999

Cell-cycle-dependent and ATM-independent expression of human Chk1 kinase.

Checkpoint genes cause cell cycle arrest when DNA is damaged or DNA replication is blocked. Although a human homolog of Chk1 (hChk1) has recently been reported to be involved in the DNA damage checkpoint through phosphorylation of Cdc25A, B, and C, it is not known at which phase(s) of the cell cycle hChk1 functions and how hChk1 causes cell cycle arrest in response to DNA damage. In the present study, we demonstrate that in normal human fibroblasts (MJ90), hChk1 is expressed specifically at the S to M phase of the cell cycle at both the RNA and protein levels and that it is localized to the nucleus at this time. hChk1 activity, as determined by phosphorylation of Cdc25C, is readily detected at the S to M phase of the cell cycle, and DNA damage induced by UV or ionizing radiation does not enhance the expression of hChk1 or its activity. Furthermore, hChk1 exists in an active form at the S to M phase in fibroblasts derived from patients with ataxia telangiectasia (AT) which lack the functional AT mutated (ATM) gene product, suggesting that hChk1 expression is independent of functional ATM. Taken together with the findings that phosphorylation of Cdc25C on serine 216 is increased at the S to M phase, it is suggested that at this particular phase of the cell cycle, even in the absence of DNA damage, hChk1 phosphorylates Cdc25C on serine 216, which is considered to be a prerequisite for the G2/M checkpoint. Thus, hChk1 may play an important role in keeping Cdc25C prepared for responding to DNA damage by phosphorylating its serine residue at 216 during the S to M phase.

Ataxia Telangiectasia Mutated Proteins↗
PubMed1999

The FANCA gene in Japanese Fanconi anemia: reports of eight novel mutations and analysis of sequence variability.

Fanconi anemia (FA), an autosomal recessive disorder characterized by a progressive pancytopenia associated with congenital anomalies and high predisposition to malignancies, is a genetically and clinically heterogeneous disease. At least eight complementation groups (FA-A to FA-H) have been identified with their relative prevalence varying among the ethnical backgrounds. Recently, responsible genes, FANCA and FANCC, have been cloned. This report describes mutations of the FANCA gene, which we studied by direct sequencing of cDNA with confirmation on genomic DNA in 15 unclassified Japanese FA patients. A total of 19 sequence alterations were identified, of which 10 (six missense and four silent alterations) were likely to be nonpathogenic polymorphism. The remaining nine alterations, of which eight were novel mutations, were assumed to be pathogenic and consisted of two missense mutations and seven mutations resulting in truncation of gene product, demonstrating a wide allelic heterogeneity. The pathogenic mutations were found in 12 patients (80%); they were either homozygous or compound heterozygous in 10 patients, apparently heterozygous in two patients and none in three patients. We conclude that the sequence variability is intrinsic to the FANCA gene and that the relative prevalence of the FA-A subtype is unusually high in Japanese FA patients.

DNA Mutational Analysis↗
PubMed1999

Intracellular signaling pathways in human eosinophil activation: role of a beta2 integrin, alphaMbeta2.

Cellular adhesion is crucial roles for eosinophil effector functions such as degranulation. Here, we focused on the role of a beta2 integrin, alphaMbeta2, in intracellular signaling pathways of human eosinophil activation. We found that the ligation of alphaMbeta2 triggers the activation of an intracellular signaling cascade, including protein tyrosine phosphorylation and phosphoinositide turnover, and subsequent cellular degranulation in human eosinophils. These signaling events may play important roles in adhesion-dependent cellular functions of eosinophils.

Cell Adhesion↗
PubMed1999

Copper increases in both plasma and red blood cells at the onset of acute hepatitis in LEC rats.

Ceruloplasmin is excreted mostly in the apo-form in Wilson's disease patients and Long-Evans rats with a cinnamon-like coat color (LEC rats), an animal model for Wilson's disease, and hence the concentration of Cu in the plasma is low. However, it increases toward and at the onset of acute hepatitis in LEC rats, the increased Cu in the plasma being bound to ceruloplasmin, metallothionein and albumin. Changes in the concentration of Cu in red blood cells (RBCs) were monitored with age for the first time together with that in the plasma in LEC rats. Cu in the RBCs was found to increase to a 5-7 times higher level than that in the plasma toward the onset and peaked at the onset, the pattern being similar to that in the plasma. The source of the Cu increase in the RBCs was discussed, and it was assumed that the so-called free Cu ions that leak from the damaged hepatocytes are bound to albumin and/or taken up by the RBCs.

Animals↗
PubMed1998

Specificity of mutations in the PMS2-deficient human tumor cell line HEC-1-A.

The spectrum of mutations was determined at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in the human uterine tumor cell line HEC-1-A which is defective in the mismatch repair gene hPMS2. The mutation frequency at the hprt locus in HEC-1-A was about two orders higher than that in wild type repair-proficient cells. The fifty-eight mutations detected were exclusively point mutations, with frameshifts of one base deletion/addition predominating (66%) the remaining were base substitutions. All the frameshift mutations occurred at sites of monotonous repeating sequences, including six consecutive guanine bases site which was the hot spot for the addition of one G that contributed 60% of the total mutations. Although the observed specificity of mutations in HEC-1-A apparently resembled that of the hMLH1-deficient cell line HCT116 [Ohzeki, S., Tachibana, A., Tatsumi, T., Kato, T., 1997. Spectra of spontaneous mutations at the hprt locus in colorectal carcinoma cell lines defective in mismatch repair. Carcinogenesis, 18, 1127-1133.], the pronounced increase of +/-1 bp frameshifts and the reduced incidence of C-->T transitions at the CpG site suggest that the hPMS2 gene product may have an additional function in the mismatch repair process independent of it's role in the hMutLalpha heterodimer.

Adenosine Triphosphatases↗
PubMed1998

Effects of calmodulin inhibitors on cyprid larvae of the barnacle, Balanus amphitrite.

During our study on signal transduction systems involved in larval settlement and metamorphosis of the barnacle Balanus amphitrite, we could detect calmodulin, a major intracellular calcium-binding protein, in both cyprids and adult barnacles using immunoblot technique. In order to examine roles of calmodulin in larval settlement and metamorphosis, we examined the effects of calmodulin inhibitors involved in phosphodiesterase (PDE), myosin light chain kinase (MLCK), calmodulin kinase II (CaM-II) on cyprids. Calcium-calmodulin-dependent PDE inhibitors inhibited larval attachment and metamorphosis in a dose-dependent manner. In contrast, cyclic AMP (cAMP)-dependent PDE inhibitors promoted larval attachment and metamorphosis, while cyclic GMP (cGMP)-dependent PDE inhibitors did not show such effect. Thus, PDE activity may depend on cAMP rather than calmodulin or cGMP in promotion of larval attachment and metamorphosis. Moreover, calmodium inhibitors involved in MLCK or CaM-II inhibited larval behaviors for attachment and metamorphosis. These results suggest that calmodulin, which is present in both adult barnacles and cyprids, may be involved in enzyme reactions such as MLCK or CaM-II rather than PDE in B. amphitrite cyprids.

Animals↗
PubMed1998

Improved hatching for in vitro quail embryo culture using surrogate eggshell and artificial vessel.

The establishment of avian embryonic culture is important both for the analysis of the developmental process and the establishment of transgenic chickens that produce useful biological materials in eggs. However, the hatchability of cultured embryos has been approximately 50%. We identified that the low rate of hatchability of cultured embryos was caused by limited oxygen and calcium availability. In quail embryo culture using chicken eggshell as a culture vessel, viability in the middle stage of culture was improved and 30% of embryos were hatched by oxygen enrichment. Furthermore, hatchability increased to 80% by supplementation with calcium lactate in addition to oxygen aeration. In the present study, a fully artificial vessel for quail embryo culture was designed using a gas-permeable Teflon membrane. By the addition of fine eggshell powder and calcium lactate, quail embryos grew and developed normally, and 43% of embryos hatched. Although the hatchability was lower than that of cultures using a surrogate eggshell, we achieved in hatching an avian embryo using a fully artificial vessel.

Animals↗
PubMed1997

Spectra of spontaneous mutations at the hprt locus in colorectal carcinoma cell lines defective in mismatch repair.

Spectra of spontaneous mutations at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in colon carcinoma cell lines HCT116 and HCT-15 deficient in mismatch repair and displaying mutator phenotypes were determined. HCT116 and HCT-15 cells, respectively, harbour a mutation in the mismatch repair gene hMLH1 and GTBP. The mutation frequency at the hprt locus in both cell lines was elevated by about two orders, but the microsatellite instability in HCT116 cells was one order higher than in HCT-15 cells. Except for one mutant of HCT-15, all the mutations (114/115) were point mutations; base substitutions of various types and frameshifts (deletions/insertions of less than a few bases, predominantly of +/-1 bp). Base substitutions (57%) and frameshifts (43%) occurred at a comparable rate in HCT116, whereas base substitutions (92%) were the major mutational events in HCT-15. Most frameshifts in HCT116 occurred at sites of monotonous or short tandem repeating sequences, and two of these sites, where there was a run of six Gs and four As, were hot spots. Three hot spot sites of base substitutions were found in HCT-15; two of them at splice acceptor sites, the other at the CpG site shared with HCT116. The distinct mutation spectra of the HCT116 and HCT-15 cell lines may reflect functional differences in the hMLH1 and GTBP gene products in mismatch repair. The gene product GTBP may be involved in the preferential repair of base mismatches, and MLH1 in the repair of both base mismatches and deletions/insertions of less than a few bases. These results suggest that mismatch repair deficiency affects the microsatellite stability as widely reported in colorectal tumour cells, but that it may not severely affect chromosome integrity as the karyotypes of these tumour cells are, unlike other tumour cells, relatively stable.

Colorectal Neoplasms↗
PubMed1997

A high prevalence of functional inactivation by methylation modification of p16INK4A/CDKN2/MTS1 gene in primary urothelial cancers.

We analyzed the genetic and epigenetic alterations of p16INK4A/CDKN2/MTS1 gene (MTS1 gene) in 38 primary urothelial cancers. Genetic alterations of the MTS1 gene consisted of one base substitution mutation in exon 2 (2.6%) and 6 homozygous deletions (16.2%). Hypermethylation of the 5' CpG island in exon 1 of the MTS1 gene was observed in 12 tumors (37.5%). Consequently, 19 of 38 tumors (50%) showed genetic alterations or epigenetic hypermethylation of the MTS1 gene. Retention of hypermethylated MTS1 gene(s) in 36% of the tumors showing loss of heterozygosity at the critical region indicates that the methylation modification could be an initial event followed by genomic rearrangements associated with total loss of MTS1 gene function. Immunohistochemical analysis of MTS1 expression revealed that all the tumors with genetic alterations of the MTS1 gene and 9 of 12 highly methylated tumors displayed an absence of MTS1 nuclear antigen. Genetic and epigenetic changes of the MTS1 gene were not correlated with the grade and stage of tumors, indicating that these alterations are early events in urothelial carcinogenesis, in which functional inactivation by hypermethylation is a predominant mechanism.

Cyclin-Dependent Kinase Inhibitor p16↗
PubMed1997

Spectrum of spontaneous mutations in the cyclic AMP receptor protein gene on chromosomal DNA of Escherichia coli.

We determined 46 spontaneous mutations occurring in the cyclic AMP receptor protein gene (crp) on the chromosomal DNA of Escherichia coli by the use of PCR cloning. Of 24 base substitutions, 17 were transversions and 7 transitions including all types of base substitutions. The frequency of the changes of A:T base pairs was similar to that of G:C pairs, suggesting that A:T pair is also a target for base substitution. Frameshifts including seven-1 and four +1 frameshifts occurred at the sites of a run of identical bases. Deletions extending 18 and 172 bases occurred at the sites where the deleted sequences were flanked by short repeated sequences at the junction. The insertions of IS2 element or its inverted sequence were detected in two and six mutations, respectively. The assay system of the mutation used here is available for the determination of the mutational spectrum of base substitutions.

Amino Acid Sequence↗
PubMed1997

Increased pain threshold following electroacupuncture: analgesia is induced mainly in meridian acupuncture points.

UNLABELLED: Pain thresholds were determined before and after electroacupuncture of the dorsal aspect acupuncture points (AP) of the hand and non acupuncture points (NAP) located 15 mm from the traditional acupuncture points to assess changes in pain threshold thus provoked. METHODS: In eight volunteers the pain threshold of specific points was determined before and after acupuncture in the Hegu point (L.I. 4), at the back of the hand. A pressure dolorimeter was used to evaluate pain threshold at the Yangxi (L.I. 5) and Quchi (L.I. 11) points and at sites 15 mm from them. The effects on pain threshold were also measured at Yingxiang (L.I. 20) on both sides. RESULTS: Before electrostimulation there were no significant differences among the pain thresholds in both AP and NAP. After electrostimulation of the Yangxi point, pain threshold raised from 5.20 kg/sq.cm to 9.20 kg/sq.cm (p < 0.01); acupuncture at Quchi caused the threshold to increase from 5.36 kg/sq.cm to 9.20 kg/sq.cm (p < 0.01) and Yingxiang stimulation changed threshold from 2.63 kg/sq.cm to 3.83 kg/sq.cm (p < 0.051) at the point on the same side and from 2.26 kg/sq.cm to 3.90 kg/sq.cm (p < 0.05) in the opposite side. Before electroacupuncture the pain thresholds at all the tested sites were not statistically different (p > 0.1). After electrostimulation the pain threshold increased 77% at L.I. 5 but went up just 9% and 6% 15 mm from L.I. 5 (p < 0.01); threshold increased by 70% at L.I. 11 but only by 6% and 7% (p < 0.01) 15 mm from L.I. 11. CONCLUSIONS: The pain threshold increased significantly in all tested sites after electroacupuncture but the analgesic effect was predominant in those points lying along the acupuncture meridians.

Acupuncture Analgesia↗