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Biomedical subjects

Koichi Ito

Publications and source records attributed to Koichi Ito.

At least 91 records · Page 5Linked to original sources
PubMed2003

Dysadherin: expression and clinical significance in thyroid carcinoma.

Dysadherin is a cancer-associated cell membrane glycoprotein. Its cDNA encodes 178 amino acids, including a putative signal sequence, a potential O-glycosylated extracellular domain, a single transmembrane domain, and a short cytoplasmic tail. Dysadherin is believed to down-regulate the expression of E-cadherin, the prime mediator of cell-cell adhesion in epithelial cells, by a posttranscriptional mechanism and promote the metastasis of carcinoma cells. To evaluate the association between dysadherin expression and E-cadherin expression in thyroid carcinoma, immunostaining for dysadherin and E-cadherin was performed in 51 papillary, 10 follicular, and 31 undifferentiated carcinomas. Immunoreactivity for dysadherin, localized at cell-cell boundaries, was detected in 39 of the 51 papillary carcinomas and all 31 undifferentiated carcinomas but not in the follicular carcinomas or normal thyroid tissue controls. Dysadherin expression was significantly higher in undifferentiated carcinoma than in papillary carcinoma and follicular carcinoma and showed significant negative correlation with E-cadherin expression. The degree of dysadherin expression was significantly associated with the prognosis, occurrence of secondary undifferentiated carcinomas, size of the primary tumor, and metastasis to the regional lymph nodes and lungs. In conclusion, a process involving increased dysadherin expression may lead to an adverse clinical outcome.

Adult↗
PubMed2003

Detection of Streptococcus anginosus and 8-hydroxydeoxyguanosine in saliva.

Several studies have demonstrated a close association between Streptococcus (S.) anginosus infection and head and neck cancer. Accumulation of 8-hydroxy-deoxyguanosine (8-OHdG), which may result from the continuous generation of reactive oxygen species associated with chronic inflammation, has been reported in human preneoplastic lesions and in cancerous tissues. The purpose of the present investigation was to assess the salivary levels of S. anginosus and 8-OHdG in patients with periodontitis. Salivary levels of S. anginosus were measured by real-time PCR. S. anginosus was detected in 28 out of 38 (73.7%) of subjects. The 8-OHdG level was significantly higher in patients positive for S. anginosus than in patients negative for the bacterium. A significant decrease in S. anginosus and 8-OHdG levels was observed after initial periodontal treatment. Our findings indicate that, although the levels of S. anginosus are relatively low, there is a correlation between the salivary level of S. anginosus and 8-OHdG, and that periodontal treatment can decrease the levels of these hazard factors.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2003

Buccal and coronal bone augmentation using forced eruption and buccal root torque: a case report.

The following case report describes the buccal and coronal bone augmentation around an irretrievable tooth using forced eruption and buccal root torque for immediate nonsubmerged implant placement. A mandibular left second premolar with degree 2 mobility, severe buccal bone resorption, and interproximal angular bony defects was subjected to forced eruption and buccal root torque. Five months after this process, the tooth was displaced 15 mm coronally and the root apex faced buccally. Buccal and coronal bone augmentation and soft tissue enlargement were evident at reentry surgery. This technique enabled proper implant placement in a situation where the bone was compromised.

Alveolar Ridge Augmentation↗
PubMed2002

Practical synthesis of chiral emopamil left hand as a bioactive motif.

An asymmetric synthesis of (2S)-2-(2-isopropyl)-5-hydroxy-2-phenylpentanenitrile (emopamil left hand, 2) has been completed by use of the MAD (methyl aluminum bis(4-methyl-2,6-di-tert-butylphenoxide)-induced rearrangement of a chiral epoxyalcohol as the key reaction. The stereochemistry of the chiral quaternary center was confirmed by transformation of 2 to (S)-noremopamil. This method requires minimal purification procedures and affords high chemical and optical yields. Acid-catalyzed isomerization of an allylaldehyde and retro-aldol type racemization at the quaternary carbon of a nitrile-alcohol were encountered.

Catalysis↗
PubMed2002

Deficiency of triad formation in developing skeletal muscle cells lacking junctophilin type 1.

Junctophilins (JP-1, JP-2, and JP-3) are transmembrane proteins expressed in the junctional membrane complexes in excitable cells. Both JP-1 and JP-2 are co-expressed in the triads of skeletal muscle, but only JP-2 is expressed in cardiac muscle. We analyzed the roles played by JP-1 and JP-2 in triad formation in skeletal muscle by comparing developing skeletal muscles in wild-type and JP-1-knockout (KO) mice (both before and after birth). In the skeletal muscles of embryos, most of the couplings between sarcoplasmic reticulum (SR) and transverse tubule (T-tubule) were diads, with triads being very scarce. The number of triads increased markedly after birth in wild-type mice. However, there was no increase in the number of triads in the neonates of JP-1-KO mice, and they died within 1 day after birth. JP-2 expression was constant before and after birth, while expression of JP-1 increased with birth. Quantitative and morphological differences were not seen between wild-type and JP-1-KO mice in the formation of diads in the period just before the JP-1-KO mice died. The SR swelled and developed large vacuoles in skeletal muscle cells just before the JP-1-KO mice died. The present results strongly suggest that JP-1 and JP-2 play important roles in the formation of triads and diads, respectively, during the development of skeletal muscle in mouse.

Animals↗
PubMed2002

Omnipotent decoding potential resides in eukaryotic translation termination factor eRF1 of variant-code organisms and is modulated by the interactions of amino acid sequences within domain 1.

In eukaryotes, a single translational release factor, eRF1, deciphers three stop codons, although its decoding mechanism remains puzzling. In the ciliate Tetrahymena thermophila, UAA and UAG codons are reassigned to Gln codons. A yeast eRF1-domain swap containing Tetrahymena domain 1 responded only to UGA in vitro and failed to complement a defect in yeast eRF1 in vivo at 37 degrees C. This finding demonstrates that decoding specificity of eRF1 from variant code organisms resides at domain 1. However, the wild-type eRF1 hybrid fully restored the growth of eRF1-deficient yeast at 30 degrees C. Tetrahymena eRF1 contains a variant sequence, KATNIKD, at the tip of domain 1. The TASNIKD variant of hybrid eRF1 rendered the eRF1-nullified yeast viable, although in an in vitro assay, the same hybrid eRF1 responded only to UGA. Nevertheless, the yeast eRF1 bearing the KATNIKD motif instead of the TASNIKS heptapeptide present in higher eukaryotes remains omnipotent in vivo. Collectively, these data suggest that variant genetic code organisms like Tetrahymena have an intrinsic potential to decode three stop codons in vivo, and that interaction within domain 1 between the KAT tripeptide and other sequences modulates the decoding specificity of Tetrahymena eRF1.

Amino Acid Sequence↗
PubMed2002

A tripeptide discriminator for stop codon recognition.

Only recently has it been established that a tripeptide in the bacterial release factors (RFs), RF1 and RF2, is responsible for the stop codon recognition. This functional mimic of the anticodon of tRNA is referred to as a tripeptide 'anticodon' or a tripeptide discriminator. Here we review the experimental background and process leading to this discovery, and strengthen functional evidence for the tripeptide determinant for deciphering stop codons in mRNAs in prokaryotes.

Codon, Terminator↗
PubMed2002

Polypeptide release at sense and noncognate stop codons by localized charge-exchange alterations in translational release factors.

The mechanism of stop codon recognition during translation has long been a puzzle. Only recently has it been established that a tripeptide in the bacterial release factors (RFs) 1 and 2 serves as the "anticodon" in deciphering stop codons in mRNA. However, the molecular basis of the accuracy of stop codon recognition is unknown. Although specific tripeptides in the RFs are primarily responsible for selective reading of cognate stop codons, charge-flip variant RF proteins, altered at conserved Glu residues adjacent to the tripeptide-anticodon, are shown here to be crucial to codon recognition. Changes of these Glu residues are capable of triggering polypeptide release at noncognate stop codons and also at sense codons. These changes also reverse the growth inhibition by RFs containing "harmful" tripeptide-anticodon changes. These findings suggest that electrostatic interactions involving negative charges in domain C of the RFs mediate their accurate docking in the ribosome. Our results also establish that the charge flipping creates a phenotype/translation termination by "codon bypassing" via relaxed positioning of the RF tripeptide-anticodon in the decoding pocket of the ribosome.

Amino Acid Sequence↗
PubMed2002

Elongation factor G participates in ribosome disassembly by interacting with ribosome recycling factor at their tRNA-mimicry domains.

Elongation factor G (EF-G) is a G protein with motor function that drives two target molecules, a tRNA in the translating ribosome and the ribosome recycling factor (RRF) in the post-termination complex. How G protein motor action is transmitted to RRF is unknown. Thermus thermophilus RRF is nonfunctional in Escherichia coli. It became functional upon introducing a plasmid expressing E. coli EF-G with surface changes in its tRNA-mimic domain or by replacing the E. coli EF-G tRNA-mimic domain by the Thermus domain. Thermus RRF could also be activated by introducing surface substitutions in its anticodon arm-mimic region. These gain-of-function phenotypes depend on the combination of heterologous EF-G and RRF alleles. These mutational studies suggest that EF-G motor action is transmitted to RRF by specific surface contacts between the domains that mimic the anticodon arm.

Amino Acid Sequence↗
PubMed2002

In situ localization and in vitro expression of osteoblast/osteocyte factor 45 mRNA during bone cell differentiation.

The in situ localization of osteoblast/osteocyte factor 45 (OF45) mRNA during bone formation has been examined in the rat mandible from embryonic day 14 (E14) up to postnatal 90-day-old Wistar rats. Gene expression was also examined during cell culture not only in primary rat osteoblast-like cells but also in two clonal rat osteoblastic cell lines with different stages of differentiation, ROB-C26 (C26) and ROB-C20 (C20) using Northern blot analysis. The C26 cell is a potential osteoblast precursor cell line, whereas the C20 cell is a more differentiated osteoblastic cell line. At E15 osteoblast precursor cells differentiated into a group of osteoblasts, some of which expressed the majority of non-collagenous proteins, whereas no expression of OF45 was observed in these cells. Intercellular matrices surrounded by osteoblasts were mineralized at E16. Subsequently, the number of osteoblasts differentiated from osteoblast precursor cells was increased in association with bone formation. At E17, the first expression of OF45 mRNA was observed only in a minority of mature osteoblasts attached to the bone matrix, but not in the rest of less mature osteoblasts. At E20, concomitant with the appearance of osteocytes, OF45 mRNA expression was observed not only in more differentiated osteoblasts that were encapsulated partly by bone matrix but also in osteocytes. Subsequently, osteocytes increased progressively in number and sustained OF45 mRNA expression in up to 90-day-old rats. Northern blot analysis of the cultured cells with or without dexamethasone treatment revealed that the gene expression of OF45 correlated well with the increased cell differentiation. These results indicate that OF45 mRNA is transiently expressed by mature osteoblasts and subsequently expressed by osteocytes throughout ossification in the skeleton and this protein represents an important marker of the osteocyte phenotype and most likely participates in regulating osteocyte function.

Animals↗
PubMed2002

Hepatocyte growth factor (HGF) in periodontal disease: detection of HGF in gingival crevicular fluid.

Hepatocyte growth factor (HGF) acts as a mitogen, motogen, morphogen, anti-apoptotic factor, and scatter factor for various kinds of epithelial cells. It is a protein secreted by mesenchymal cells such as fibroblasts, and promotes motility and matrix invasion of epithelial cells. To clarify whether HGF is involved in periodontal disease, this study was conducted to determine whether HGF is present in gingival crevicular fluid (GCF) and to investigate the relationship between levels of HGF and the clinical parameters of periodontal disease, probing depth (PD), gingival index (GI) and bleeding on probing (BOP). We examined and collected GCF samples from 80 sites in 38 subjects with periodontal or other oral diseases. The concentrations of HGF, IL-1beta and PGE2 were determined by ELISA, and active collagenase activity was determined by functional assay. The HGF level correlated positively with PD and GI, and was significantly higher in specimens from BOP-positive sites and those where PD exceeded 4 mm compared with those from sites that were BOP-negative or with a PD less than 3 mm. There was a significant positive correlation between the concentrations of HGF and IL-1beta. These results indicate that the HGF level in GCF correlates well with clinical parameters of periodontal disease, and suggest that HGF may be involved in epithelial invasion through its role as a scatter factor.

Adult↗
PubMed2002

The important role of operations in the management of anaplastic thyroid carcinoma.

BACKGROUND: Anaplastic thyroid carcinoma is a rare and highly lethal neoplasm. We investigated whether operations have an impact on the survival of patients who have anaplastic carcinoma without distant metastasis. METHODS: Between 1989 and 1999, 40 consecutive patients with anaplastic carcinoma, without distant metastasis at the time of presentation or during local treatment, were reviewed. The cumulative survival rates and 1-year survival rates were compared. RESULTS: Eleven patients had a small focus of anaplastic carcinoma in a differentiated carcinoma, and 29 patients had ordinary anaplastic thyroid carcinoma. Surgical debulking was performed in 26 patients. Radiotherapy was used for 31 patients and chemotherapy for 19 patients. The 1-year survival rates of the patients with incidental anaplastic carcinoma, ordinary anaplastic carcinoma who underwent operations, and ordinary anaplastic carcinoma who did not undergo operations were 73%, 60%, and 21%, respectively. A significantly higher cumulative survival rate was observed in patients with incidental anaplastic carcinoma than in those with ordinary anaplastic carcinoma. A significantly better outcome was obtained by surgical debulking of ordinary anaplastic carcinoma. CONCLUSIONS: Patients with incidental anaplastic carcinoma tended to have a good outcome, but some had a poor prognosis. Surgical debulking improved the outcome of patients with ordinary anaplastic carcinoma.

Carcinoma↗
PubMed2002

Thyroid-stimulating hormone induces interleukin-18 gene expression in FRTL-5 cells: immunohistochemical detection of interleukin-18 in autoimmune thyroid disease.

Interleukin (IL)-18 is a cloned cytokine that was identified originally as a factor having potent interferon (IFN)-gamma-inducing activity on Kupffer cells. First, we analyzed IL-18 gene expression by reverse transcription-polymerase chain reaction (RT-PCR) in rat thyroid FRTL-5 cells and human thyroid tissue samples. The expression of IL-18 mRNA in FRTL-5 cells was enhanced by thryoid-stimulating hormone (TSH) in a dose-dependent manner. 8-Bromo-cyclic adenosine monophosphate (cAMP) also increased in IL-18 mRNA levels. Furthermore, TGCT clones that exhibited an increase in intracellular cAMP accumulation showed an increased IL-18 mRNA signal when compared to controls. Taken together, these data suggested that the effect of TSH on IL-18 gene expression was mediated by activating protein kinase A. Treatment of FRTL-5 cells with the antithyroid drug, methimazole (MMI), suppressed this stimulatory action of TSH on IL-18 gene expression. Next, we examined IL-18 expression in human thyroid tissue derived from patients with autoimmune thyroid diseases (ATD). RT-PCR and immunohistology demonstrated that human thyroid follicular cells expressed IL-18. Especially in thyroid tissue from a patient with Hashimoto's thyroiditis, expression was more diffuse and extensive, generally observed in close relation to a lymphocytic infiltrate. Also, IL-18 protein was distributed in the same follicles that express Fas-L and HLA-DR. This study is the first to demonstrate the detection of IL-18 in the thyroid gland. The frequent expression of IL-18 in thyrocytes suggests that IL-18 itself might be a secreted immunomodulator in ATD.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2002

Effect of enamel matrix derivative on the differentiation of C2C12 cells.

BACKGROUND: Although enamel matrix derivative (EMD) can initiate de novo cementum and bone formation by stimulating and inducing differentiation of mesenchymal cells in the periodontal ligament, the molecular mechanism of this phenomenon is not fully understood. The purpose of this study was to determine the effect of EMD on the differentiation of pluripotential mesenchymal cells. METHODS: A typical pluripotential mesenchymal cell line, C2C12, was used to clarify the effect of EMD on cell differentiation. The cells were cultured in 5% serum-containing medium to induce cell differentiation, either with or without the addition of EMD. Differentiation to myoblasts was analyzed by immunostaining of desmin and type II myosin heavy chains. Osteoblast differentiation was evaluated by measuring alkaline phosphatase (ALPase) activity. Furthermore, to verify the cell lineage after culture with EMD, mRNA expression of cellular phenotype-specific markers characterizing osteoblasts (ALPase and osteocalcin), chondroblasts (type X collagen), myoblasts (desmin and MyoD), and adipocytes (lipoprotein lipase) was studied using semiquantitative reverse transcription-polymerase chain reaction. RESULTS: C2C12 cells cultured in differentiation medium without EMD altered their phenotype to myoblasts, exhibiting positive reactions to desmin and myosin heavy chains by immunological analysis. However, the cells cultured in the presence of EMD were strongly inhibited from developing into myoblasts, and showed high ALPase activity that was approximately 2 to 4 times greater than that of the vehicle. The mRNA expression of ALPase, osteocalcin, and type X collagen was increased markedly by the EMD-stimulated medium, whereas the expression of desmin, MyoD, and lipoprotein lipase was drastically decreased. CONCLUSIONS: Our study provides clear evidence that EMD converts the differentiation pathway of C2C12 cells into the osteoblast and/or chondroblast lineage.

Adipocytes↗
PubMed2002

New biomarker evidence of oxidative DNA damage in whole saliva from clinically healthy and periodontally diseased individuals.

BACKGROUND: There is an increasing body of evidence implicating reactive oxygen species in the pathogenesis of periodontal tissue destruction. 8-Hydroxy-deoxyguanosine (8-OHdG) is one of the most commonly used markers to evaluate oxidative damage in a number of disorders including chronic inflammatory diseases. The aim of the present study was to evaluate 8-OHdG levels in whole saliva of patients with periodontitis and to assess the changes after initial treatment. METHODS: Saliva samples were collected from 78 patients with untreated periodontitis and 17 healthy control subjects. Clinical parameters and levels of 8-OHdG were assessed first to establish a baseline and again after initial periodontal treatment from 15 patients. 8-OHdG levels were determined by enzyme-linked immunosorbent assay. RESULTS: The mean value of 8-OHdG in the saliva of periodontally diseased subjects, 4.28 +/- 0.10 ng/ml, was significantly higher (P<0.01) than that of clinically healthy subjects (1.56 +/- 0.10 ng/ml). A significant decrease in salivary 8-OHdG was observed after therapy (P<0.01). CONCLUSION: In the present study, we evaluated for the first time 8-OHdG levels in whole saliva of patients with periodontitis and assessed changes after initial periodontal treatment. Our study indicated that 8-OHdG levels in saliva appear to reflect the status of periodontal health.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

Hepatocyte growth factor (HGF) system in gingiva: HGF activator expression by gingival epithelial cells.

Hepatocyte growth factor (HGF) acts as a mitogen, motogen, morphogen, and anti-apoptotic factor for various kinds of epithelial cells. We previously showed that periodontal ligament and gingival fibroblasts secreted an HGF-like chemoattractant for a gingival epithelial cell line and found that the HGF content of gingival crevicular fluid was well correlated with clinical parameters and interleukin-1beta level. Since HGF is secreted as an inactive form (proHGF), and converted to an active form by serine proteases such as HGF activator (HGFA), extracellular processing of proHGF is presumed to be critical in the regulation of HGF activity. To examine the role of the HGF system in epithelial invasion followed by loss of connective tissue attachment in periodontitis, mRNA expression of HGF, its receptor (c-met) and HGFA in gingival tissues was monitored. Ten gingival biopsies were obtained, and epithelium and connective tissues were separated by enzymatic digestion. The gene expression of HGF and keratinocyte growth factor (KGF) in gingival connective tissue, and c-met, HGFA and KGF receptor (KGFR) in gingival epithelial tissues was monitored using RT-PCR. Furthermore, HGFA protein in the conditioned medium of cultured primary gingival epithelial cells was examined using Western blotting. All the connective tissue samples expressed KGF, and 8 out of 10 samples expressed HGF. All the epithelial samples expressed KGFR and c-met, whereas 5 out of 10 samples expressed HGFA. Protein expression of HGFA by cultured primary gingival epithelial cells was also confirmed. In terms of local production and activation of HGF in gingival tissue, these results suggest that synergistic expression of HGF in connective tissue and HGFA expression in epithelium may contribute to disease progression in periodontitis.

Biopsy↗