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Biomedical subjects

K Sekiguchi

Publications and source records attributed to K Sekiguchi.

At least 73 records · Page 4Linked to original sources
PubMed1998

Significance of circulating hepatocyte growth factor level as a prognostic indicator in primary breast cancer.

The circulating hepatocyte growth factor (HGF)/scatter factor level is frequently increased in advanced cancer patients. In this study, we have assessed the prognostic value of the circulating HGF level determined by enzymatic immunoassay in primary breast cancer patients. Of 200 primary breast cancer patients, 54 (27.0%) showed the increase of serum HGF level according to the age-matched cutoff values. The prognosis of the patients with the increased HGF level was statistically worse than that of the patients with normal HGF level (P = 0.0001, log-rank test). Multivariate analysis confirmed that the increase in HGF level was an independent prognostic indicator in primary breast cancer patients. In the background analysis, the increase in serum HGF level was significantly associated with tumor size, nodal status, and histological evidence of venous invasion. The data indicate that up-regulation of the circulating HGF level may predict systemic tumor spread and early relapse in primary breast cancer patients.

Adult↗
PubMed1997

Modulation of cell-adhesive activity of fibronectin by the alternatively spliced EDA segment.

Fibronectin (FN) has a complex pattern of alternative splicing at the mRNA level. One of the alternatively spliced segments, EDA, is prominently expressed during biological processes involving substantial cell migration and proliferation, such as embryonic development, malignant transformation, and wound healing. To examine the function of the EDA segment, we overexpressed recombinant FN isoforms with or without EDA in CHO cells and compared their cell-adhesive activities using purified proteins. EDA+ FN was significantly more potent than EDA- FN in promoting cell spreading and cell migration, irrespective of the presence or absence of a second alternatively spliced segment, EDB. The cell spreading activity of EDA+ FN was not affected by antibodies recognizing the EDA segment but was abolished by antibodies against integrin alpha5 and beta1 subunits and by Gly-Arg-Gly-Asp-Ser-Pro peptide, indicating that the EDA segment enhanced the cell-adhesive activity of FN by potentiating the interaction of FN with integrin alpha5beta1. In support of this conclusion, purified integrin alpha5beta1 bound more avidly to EDA+ FN than to EDA- FN. Augmentation of integrin binding by the EDA segment was, however, observed only in the context of the intact FN molecule, since the difference in integrin-binding activity between EDA+ FN and EDA- FN was abolished after limited proteolysis with thermolysin. Consistent with this observation, binding of integrin alpha5beta1 to a recombinant FN fragment, consisting of the central cell-binding domain and the adjacent heparin-binding domain Hep2, was not affected by insertion of the EDA segment. Since the insertion of an extra type III module such as EDA into an array of repeated type III modules is expected to rotate the polypeptide up to 180 degrees at the position of the insertion, the conformation of the FN molecule may be globally altered upon insertion of the EDA segment, resulting in an increased exposure of the RGD motif in III10 module and/or local unfolding of the module. Our results suggest that alternative splicing at the EDA exon is a novel mechanism for up-regulating integrin-binding affinity of FN operating when enhanced migration and proliferation of cells are required.

Alternative Splicing↗
PubMed1997

Reevaluation of postoperative radiotherapy for thoracic esophageal carcinoma.

PURPOSE: To reevaluate postoperative radiotherapy for thoracic esophageal carcinoma. METHODS AND MATERIALS: Reviewed were the outcome of 89 patients who underwent esophagectomy with systematic dissection of regional lymph nodes between 1988 and 1993. Of the 89 patients, 19 underwent no adjuvant treatment, 22 underwent adjuvant chemotherapy alone, and 48 underwent postoperative radiotherapy. Twelve of the 48 also underwent adjuvant chemotherapy. RESULTS: All patients who experienced local-regional recurrence had lymph node metastases at the time of surgery. The actuarial local-regional control rate at 2-year of follow-up was 94% for patients with lymph node metastases at the time of surgery who underwent postoperative radiotherapy alone or plus chemotherapy, and 74% for those who underwent adjuvant chemotherapy alone. The local-regional control rate was significantly better for those who had undergone postoperative radiotherapy (p < 0.01). CONCLUSIONS: Postoperative radiotherapy still plays an important role as adjuvant treatment.

Adult↗
PubMed1997

Evaluation of new primers for CSF1PO.

We describe new primers for the detection of the STR polymorphism at the CSF1PO locus. These primers have been designed to produce shorter amplicons (150-182 bp) than the primers in standard use (295-327 bp). The reliability of the new primers for CSF1PO typing has been demonstrated by testing on known samples and by sequence analysis. These primers are superior to the original primers with regard to electrophoretic resolution and utility for typing of severely degraded DNA.

Blood Stains↗
PubMed1997

Loss of EDB+ fibronectin isoform is associated with differentiation of alveolar epithelial cells in human fetal lung.

Cell-matrix interactions have been shown to regulate the development of the lung, particularly airway branching and alveolarization. Fibronectin is the major constituent of pulmonary extracellular matrix and exists in multiple isoforms arising from alternative RNA splicing. EDA and EDB are the two major alternatively spliced segments, the expression of which is regulated in a spatiotemporal and oncodevelopmental manner. In this study, we investigated immunohistochemically the distribution of the EDA- and EDB-containing fibronectin isoforms (referred to as EDA+ fibronectin and EDB+ fibronectin, respectively) in normal and hypoplastic human lungs at different gestational ages to explore the role of these fibronectin isoforms in alveolarization. EDA+ fibronectin was expressed around the distal airspaces throughout the development of both normal and hypoplastic lungs. In contrast, the expression of EDB+ fibronectin was restricted to the lung with morphologically immature acinar complex, typically observed in normally developing lungs of < 30 gestational weeks or in hypoplastic lungs. To further confirm the restricted expression of EDB+ fibronectin in immature acinar complex, we examined the correlation of EDB+ fibronectin expression with that of the surfactant protein SP-A, a biochemical marker for the differentiated type II pneumocytes. A clear inverse relationship between the immunoreactivities for EDB+ fibronectin and SP-A was observed in both control and hypoplastic lungs. Given the proposed importance of fibronectins in the differentiation of alveolar epithelial cells, our results suggest that the EDB segment plays a regulatory role in the differentiation of immature acinar epithelial cells into type II pneumocytes. The EDB segment may also serve as a new histochemical marker for the functional maturity of fetal lung tissues.

Alternative Splicing↗
PubMed1997

[Chemoradiation therapy for esophageal carcinoma].

Cancer of the esophagus poses a great challenge to the surgical, medical, and radiation professions. Despite standardization of resection and reconstruction techniques, extended lymph node dissection, and advances in perioperative management, the overall prognosis of patients with esophageal cancer undergoing surgical resection has not improved. Preoperative combination chemoradiation therapy in patients with squamous cell esophageal carcinoma has recently received increasing attention, because preoperative chemoradiation therapy, consisting of the concurrent combination of 5-fluorouracil, cis-platinum and radiation, appears to increase the resection rate, the rate of pathological complete responders, and survival time after esophagectomy in patients with locally advanced tumors. Overall in the trials using preoperative concurrent chemoradiotherapy, major antitumor responses have been reported in 40% to 80% of patients, and, consistently, up to 42.1% pathologic complete responses have been seen at esophagectomy. Therefore, preoperative chemoradiation therapy can be anticipated for better prognosis of the patients with locally advanced esophageal cancer.

Carcinoma, Squamous Cell↗
PubMed1997

Responses of peri-implant tissues to undisturbed plaque formation in dogs: clinical, radiographic, and microbiological findings.

The present investigation evaluated the clinical and microbiological effects of long-term undisturbed plaque formation on peri-implant tissues. Four mongrel dogs were used in the study. The mandibular 3rd and 4th premolars were extracted. Three months later, four Brånemark implants (BR, n = 8) or Integral implants (IN, n = 8) were placed in the edentulous area of each dog. After another 3 months, an abutment connection was performed. Plaque control regiment was maintained for 30 days until the superstructure was placed (Day 0: baseline). Then the plaque control program was terminated to allow gross plaque accumulation. Clinical, radiographical and microbiological data were recorded at the baseline, and at 90 and 180 days after the termination of the plaque control. Values for the clinical indices such as probing depth, plaque index and bleeding on probing increased at day 90 on both the implant and tooth sites, and remained unchanged at day 180. Significantly more implant sites showed bleeding on probing than did tooth sites. Neither implants nor tooth sites showed clinically significant changes in mobility. No distinct bone resorption was observed over time by radiography. In microscopic morphological observations, cocci dominated at the baseline, and decreased by day 180, while the proportion of motile bacteria increased. In a culture study, black-pigmented anaerobic rods, which consisted predominantly of Porphyromonas gingivalis-like bacteria, were consistently found from the baseline to day 180. No Actinobacillus actinomycetemcomitans-like organisms were isolated. These results indicate that, although the long-term plaque accumulation did not cause marked periodontal destruction, the peri-implant tissue may be more susceptible to plaque accumulation than the periodontal tissue, and that teeth may serve as a reservoir for the bacterial colonization of the implant sulcus.

Alveolar Bone Loss↗
PubMed1996

Paxillin association in vitro with integrin cytoplasmic domain peptides.

Short cytoplasmic domains of integrin heterodimers are crucial for transduction of signals generated by adhesion of cells to the extracellular matrix. Here, we describe the use of peptides mimicking the intracellular tails of integrin alpha5beta1 to assay in vitro associations with cytoskeletal proteins. Our results suggest that the focal adhesion protein, paxillin, may interact directly with the intracellular region of the integrin beta1 subunit. Paxillin is known to form stable complexes with several signaling molecules, including focal adhesion kinase. Physical interaction between paxillin and the beta1 cytoplasmic domain suggests a model in which paxillin may function as a key intermediary in integrin-mediated signal transduction.

Amino Acid Sequence↗
PubMed1996

Suppression of transformed phenotypes of human fibrosarcoma cells by overexpression of recombinant fibronectin.

Loss of fibronectin (FN) from the cell surface has been shown to be closely associated with malignant transformation of cells. To elucidate the role of the FN matrix in the modulation of malignant phenotypes, we overexpressed a full-length cDNA encoding plasma-type FN in HT1080 human fibrosarcoma cells. The cells overexpressing FN adopted a more flattened morphology and deposited a moderately developed FN matrix both in vitro and in vivo, although the level of expression of integrin alpha5beta1 remained unchanged. FN-overexpressing cells exhibited a reduced cell motility on the substratum and grew poorly when injected s.c. into nude mice. Overexpression of FN also suppressed the ability of the tumor cells to proliferate in soft agar, whereas the suppression was reversed by inclusion in soft agar of the Arg-Gly-Asp (RGD)-containing peptide and adhesion-blocking antibodies against the central cell-binding domain of FN. Neither cell motility nor growth potential was altered by overexpression of a truncated form of FN lacking the central cell-binding domain. These results, taken together, indicate that increased deposition of FN in the pericellular matrix per se can suppress the motility and growth potential of tumor cells through interaction with RGD-recognizing integrins, most likely alpha5beta1.

Animals↗
PubMed1996

DNA breaking activity and mutagenicity of soy sauce: characterization of the active components and identification of 4-hydroxy-5-methyl-3(2H)-furanone.

Soy sauce is a seasoning consumed widely in Southeast Asia. When supercoiled DNA was incubated with soy sauce at pH7.4 and 37 degrees C, extensive breaking of DNA single-strands was caused. It was found that the breaking activity was due to multiple components with different molecular weight and polarity. One of the components with the breaking activity was purified successively by extraction with ethyl acetate, thin-layer chromatography and high performance liquid chromatography, and identified as 4-hydroxy-5-methyl-3(2H)-furanone (HMF), one of the fragrant components in soy sauce. Formation of this component was found due to Maillard reaction of pentoses/amino acids. HMF was readily degraded into the compound with an endiol-ketol structure and reducing activity. Using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in an electron spin resonance-spin trapping technique, generation of hydroxyl radical in an aqueous solution of HMF was confirmed. While DNA breaking by soy sauce was little inhibited by the scavengers of active oxygen radicals, the breaking by HMF was effectively inhibited by superoxide dismutase, catalase, hydroxyl radical scavengers, spin-trapping agents, thiol compounds and metal chelating agents. Hence, DNA breaking activity of HMF was found due to generation of active oxygen radicals. HMF was found mutagenic to Salmonella bacteria without metabolic activation, probably due to generation of active oxygen radicals.

DNA↗
PubMed1996

Abrogation of lung metastasis of human fibrosarcoma cells by ribozyme-mediated suppression of integrin alpha6 subunit expression.

The interaction of tumor cells with the basement membrane plays a crucial role in tumor metastasis. VLA-6 (alpha6beta1) integrin is one of the major surface receptors for the basement membrane, specifically recognizing laminin. To study the role of VLA-6 integrin in tumor invasion and metastasis, we synthesized a ribozyme that selectively degrades the integrin alpha6 subunit mRNA. The catalytic activity of the ribozyme was verified by in vitro cleavage of alpha6 subunit mRNA. Introduction of the anti-alpha6 ribozyme gene into the human fibrosarcoma cell line HT1080 yielded stable transfectants, which expressed a significantly reduced level of integrin alpha6 mRNA. Flow cytometric analysis showed that the surface expression of VLA-6, but not other integrins, was reduced by approximately 70% in transfected cells. Ribozyme-transfected cells were less adherent to laminin-coated substrata and less invasive into reconstituted basement membrane than mock-transfected cells. When injected i.v. into nude mice, ribozyme-transfected cells produced no lung metastasis in all except 1 of 35 mice, though mock-transfected cells produced multiple lung metastases in 22 of 29 mice. Our results indicate that VLA-6 integrin plays a critical role in tumor invasion and metastasis and may serve as a potential target for eradication of tumor metastasis in the lung.

Animals↗
PubMed1996

Adherence of synovial cells on EDA-containing fibronectin.

OBJECTIVE: To investigate the role of EDA-containing fibronectin (EDA+ FN), a splice variant of FN detectable in association with cellular transformation, in the adherence of synovial cells (SC) on rheumatoid cartilage surface. METHODS: The number of SC adherent on cartilage slices or on culture plates containing either EDA+ FN or plasma FN (pFN) was enumerated under a phase-contrast microscope. The portion of the FN molecule responsible for adherence of SC onto EDA+ FN was investigated by inhibition studies using antibodies or peptide fragments. RESULTS: SC adhered more strongly on the surfaces containing EDA+ FN than on those containing pFN (P < 0.01). When monoclonal antibodies against the EDA or the carboxyl-terminal heparin-binding (Hep2) domains were used, adhesion of SC onto EDA+ FN was reduced to a level comparable with that onto pFN. FN fragments containing Hep2 or heparan sulfate inhibited the adhesion of SC onto EDA+ FN. Treatment of SC with heparitinase, but not heparinase, reduced the adhesion of SC onto EDA+ FN. CONCLUSION: EDA+ FN enhances adherence of SC on the matrix via the Hep2 region of EDA+ FN.

Alternative Splicing↗
PubMed1996

Low-temperature resistance of higher plants is significantly enhanced by a nonspecific cyanobacterial desaturase.

A broad-specificity delta 9 desaturase gene was cloned from the cyanobacterium Anacystis nidulans. The enzyme introduces a cis-double bond at the delta 9 position of both 16 and 18 carbon saturated fatty acids linked to many kinds of membrane lipids. The gene was stably introduced into tobacco plants under transcriptional control of the cauliflower mosaic virus 35S promoter, and the enzyme was targeted into plastids by the transit peptide of the pea RuBisCO small subunit. The transgenic plants had a highly reduced level of saturated fatty acid content in most membrane lipids and exhibited a significant increase in chilling resistance.

Adaptation, Physiological↗
PubMed1996

Cyclic AMP-dependent protein kinase but not protein kinase C regulates the cardiac Ca2+ channel through phosphorylation of its alpha 1 subunit.

The voltage-dependent L-type Ca2+ channel in the heart is regulated by cAMP-dependent protein kinase (PKA) and possibly by protein kinase C (PKC). We have investigated the channel modulation through phosphorylation by these protein kinases, using liposomes into which Ca2+ channels from bovine heart were reconstituted. Phosphorylation of the proteoliposomes with PKA increased the dihydropyridine-sensitive Ca2+ efflux from them by about 70%. PKA rapidly phosphorylated membrane proteins of 210 and 170 kDa. A dihydropyridine-class Ca2+ channel blocker, [3H]azidopine, specifically photo-labeled a protein of 210 kDa, suggesting that the 210-kDa phosphoprotein might be the alpha 1 subunit of the Ca2+ channel. In contrast, phosphorylation of the proteoliposomes with PKC failed to modulate the Ca2+ efflux. Although PKC catalyzed the phosphorylation of membrane proteins of 150, 130, 95, 67, and 62 kDa, the 210- and 170-kDa proteins were not phosphorylated by this kinase. These results suggest that phosphorylation of the 210-kDa protein in the cardiac sarcolemma by PKA may be responsible for modulation of the channel function, whereas modulation of the channel by PKC, if it occurs, must be the result of an indirect mechanism, e.g. phosphorylation of a cytoplasmic protein or an associated channel polypeptide, that cannot function in the reconstituted system.

Animals↗
PubMed1996

Novel peptide ligands for integrin alpha 6 beta 1 selected from a phage display library.

Integrin alpha 6 beta 1 is a major adhesion receptor for the basement membrane, specifically binding to laminin-1. To identify the peptide sequences recognized by alpha 6 beta 1, we screened a 15-mer phage display library by panning with alpha 6 beta 1 purified from human placenta. DNA sequencing of 73 randomly picked phage revealed that three clones were dominantly enriched after repeated panning with alpha 6 beta 1. None of the peptide sequences displayed on these phage showed significant homology to laminin-1. A synthetic peptide modeled after the sequence displayed by one of these phage, designated P3, was found to strongly inhibit the binding of laminin-1 to alpha 6 beta 1. This inhibitory effect of the P3 peptide seems to be specific for alpha 6 beta 1, since it did not affect the binding of fibronectin to integrin alpha 5 beta 1. A synthetic peptide with a scrambled P3 amino acid sequence barely inhibited the binding of laminin-1 to alpha 6 beta 1. When coated on a substratum after conjugation with bovine serum albumin, the P3 peptide was capable of promoting cell spreading in an alpha 6 beta 1-dependent manner, although the peptide with the scrambled sequence showed activity similar to that of a control peptide. These results taken together indicate that the P3 peptide is a novel ligand for integrin alpha 6 beta 1 with potent cell spreading activity.

Amino Acid Sequence↗
PubMed1996

[Serovar-distribution and drug-resistance of Salmonella strains isolated from domestic and imported cases in 1990-1994 in Tokyo].

A total of 3,647 non-typhoidal Salmonella strains consisting of 2,655 domestic strains and 992 imported strains isolated in Tokyo from 1990 to 1994, were examined for their serovar-distribution and their drug-resistance. The serological typing results showed that the domestic strains were classified into 15 O-groups and 96 serovars, and the imported strains were classified into 13 O-groups and 73 serovars. Among the serovars identified, Salmonella serovar Enteritidis (S. Enteritidis), S. Thompson, S. Hadar, S. Litchfield, and S. Tennessee were predominant in the domestic strains, whereas S. Hadar, S. Enteritidis, S. Anatum, S. Derby, and S. Blockley were predominant in the imported strains. The drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM, and NFLX) showed that 30.5% of the domestic strains and 40.5% of the imported strains were resistant to any of the drugs examined. The serovars of a high resistant rate during this period were S. Hadar (96.2%), S. Blockley (88.7%), S. Enteritidis (63.4%), S. Virchow (54.3%), and S. Typhimurium (51.3%) in the domestic strains and S. Krefeld (100%), S. Hadar (98.9%), S. Blockley (98.2%), S. Emek (83.3%), S. Kentucky (76.5%), S. Panama (69.2%), S. Derby (63.8%), S. Typhimurium (57.1%), S. Rissen (55.6%), and S. Agona (53.7%) in the imported strains. Drug-resistance patterns of the resistant isolates varied to 62 types. Prevalent patterns recognized were SM, TC.SM, TC.SM.KM, TC, TC.SM.KM.ABPC and CP.TC.SM.KM in the domestic strains and TC.SM, TC, CP.TC.SM.ST, TC.SM.KM, and CP.TC.SM.KM in the imported strains.

Diarrhea↗
PubMed1996

[Detection of the trh gene in Vibrio parahaemolyticus isolated from overseas travellers' diarrhea and their biochemical characteristics].

A total of 478 Vibrio parahaemolyticus strains isolated from overseas travellers' diarrhea during the last 7 years of 1989 to 1995 were examined for the production of Kanagawa hemolysin by reversed passive latex agglutination (RPLA) test. Three hundred-seventy (77.4%) out of 478 strains were positive for Kanagawa hemolysin, whereas 108 strains were weakly positive or negative. For those Kanagawa hemolysin-weakly positive or negative strains, the tdh and trh genes associated with the production of TDH (thermostable direct hemolysin) and TRH (TDH-related hemolysin), respectively, were studied by the polymerase chain reaction method. The trh gene was detected in 98 (90.7%) out of 108 strains. In 35 strains belonging to 13 serotypes such as O3: K6, O1:K33, O3:K59, the trh gene alone was detected. On the other hand, both trh and tdh genes were detected in 63 strains of 17 serotypes including O1:K69, O3:K72, O6:K46. Among the strains of 4 serotypes including O1:K56, O1:KUT, O3:KUT and O5:KUT, two types of the trh positive alone and the trh and tdh positive were observed. Of interest, all of the 98 trh-positive strains were positive for the urease hydrolysis, whereas all Kanagawa hemolysin-positive strains were not. Furthermore, the strains of serotype O6:K18 (4 strains) were positive for the fermentation of dulcitol, and the strains of serotype O1:K1 (5 strains) were indole negative. These characteristics of the strains were completely different from those of typical V. parahaemolyticus strains.

Diarrhea↗