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Biomedical subjects

S Kanda

Publications and source records attributed to S Kanda.

At least 55 records · Page 3Linked to original sources
PubMed2000

Effects of antioxidants on induction of apoptosis in bursal cells of Fabricius during in vitro cultivation.

After physically disrupting cell contacts, apoptosis of bursal cells of Fabricius was induced during in vitro cultivation. The percentage of apoptotic cells increased with incubation time and approximately 70% cells represented apoptosis after 6 hr of incubation. The induction of apoptosis was significantly inhibited by treatment of the cells with ascorbic acid (vitamin C), but not with trolox, a vitamin E analog. An intense DNA ladder pattern was shown at 6 hr post-isolation, which is a biochemical hallmark of apoptosis. Treatment of the cells with ascorbic acid inhibited the DNA fragmentation, but trolox did not. To monitor the intracellular production of reactive oxygen species (ROSs), the intensity of fluorescence emitted from DCFH-DA was measured. The intensity of fluorescence from cells incubated for 0.5-2 hr was approximately 2-fold higher than that from cells at 0 hr. The relative intensity of fluorescence decreased immediately after the addition of ascorbic acid to the cells. The intensity from the cells treated with ascorbic acid was 20-30% of that from the control cells at each incubation time. For trolox, the intensity was 50-70% of that from the control cells at each 1 to 2 hr incubation time. When ROSs-induced lipid peroxidation was assessed using cis-parinaric acid (PnA) as a monitor molecule, lipid peroxidation was found to occur in the control cells after isolation of the bursal cells. Treatment of the cells with trolox reduced lipid peroxidation, but treatment with ascorbic acid enhanced peroxidation.

Animals↗
PubMed2000

Rapid oscillation of insulin release by the rat pancreatic islets under stringent Ca2+-free conditions.

Oscillation of insulin release by the pancreatic islets was evaluated under stringent Ca(2+)-free conditions for the first time. Isolated single rat islets were exposed to 16.7 mM glucose in the presence of 1.9 mM Ca(2+), or under the stringent Ca(2+)-free conditions (Ca(2+) omission with 1 mM EGTA, 6 microM forskolin and 100 nM phorbol 12-myristate 13-acetate). Fifteen minutes after the initiation of glucose stimulation, effluent was collected at a 6-s interval, insulin was determined in duplicate by a highly sensitive insulin radioimmunoassay, and oscillation and pulsatility of release statistically analyzed. Significant oscillation of insulin release was observed in all islets irrespective of presence and absence of Ca(2+). Significant pulsatility of release was detected in 7 of 11 islets in the presence of Ca(2+) and three of six isl! ets in the absence of Ca(2+). In conclusion, high glucose elicits oscillatory insulin release both in the presence and absence of extracellular Ca(2+).

Animals↗
PubMed2000

[A case of adenoid cystic carcinoma of the trachea resected surgically after Nd-YAG laser therapy].

A case of primary tracheal tumor ablated by endoscopic Nd-YAG laser prior to tracheal sleeve resection was reported. A 53-year-old man had dry cough, bloody sputum and dyspnea. Bronchoscopic examination revealed polypoid tumor which located 2 cm below the vocal cords and obstructed the airway almost completely. After tumor vaporized by Nd-YAG laser, bronchoscopy type 200 could pass through the tracheal lumen and the length of the lesion was diagnosed within 4 cm. Biopsy specimen was confirmed adenoid cystic carcinoma. Cervical trachea was resected of six tracheal cartilage (first to sixth cartilage) combined with left thyroid lobe under collar incision and median sternotomy. The neck was fixed for ten days by tying the jaw to the anterior chest wall in order to reduce excessive tension to the anastomosis. Pathological examination revealed the tumor residual microscopically, 60 Gy of radiotherapy was conducted.

Carcinoma, Adenoid Cystic↗
PubMed1999

Role of thrombospondin-1-derived peptide, 4N1K, in FGF-2-induced angiogenesis.

Angiogenesis involves proliferation of capillary endothelial cells and formation of lumen-containing tube-like structures. A recently established murine brain capillary endothelial cell line, IBE, can either proliferate or form tube-like structures (i.e., differentiate) in response to fibroblast growth factor-2 (FGF-2), dependent on the culture conditions. The 4N1K peptide (KRFYVVMWKK), which is derived from the C-terminal cell-binding domain of thrombospondin-1 (TSP-1), inhibited tube formation, but not proliferation of IBE cells. Polyclonal antibodies against 4N1K blocked TSP-1-induced inhibition of tube formation by IBE cells. 4N1K inhibited tyrosine phosphorylation of focal adhesion kinase and FGF-2-stimulated tyrosine phosphorylation of phospholipase C-gamma in tube-forming, but not proliferating, IBE cells. The peptide also inhibited FGF-2-induced neovascularization in mouse cornea. Our results indicate that TSP-1 may exert its inhibitory effects on angiogenesis via the C-terminal cell-binding domain containing the 4N1K sequence by inhibiting tube formation by endothelial cells.

Animals↗
PubMed1999

Contribution of Src and Ras pathways in FGF-2 induced endothelial cell differentiation.

We have examined fibroblast growth factor (FGF) receptor-1 mediated signal transduction in differentiation of endothelial cells (EC). The activated FGFR-1 couples to Ras through two adaptor proteins, FRS2 and Shc. In FGF-2 treated proliferating EC, FRS2 as well as Shc are tyrosine phosphorylated and interact with Grb2. In contrast, in FGF-2 treated differentiating cells, Shc, but not FRS2, is engaged in Grb2-interactions. Sustained MAP kinase activity has previously been implicated in differentiation. In FGF stimulated proliferating and differentiating endothelial cells, the MAP kinase Erk2 is activated in a sustained manner. Inhibition of MEK and MAP kinase activity by PD98059 treatment of cells, still allows EC tube formation. The FGFR-1 mediates activation of protein kinase C (PKC) through direct binding and activation of phospholipase C-gamma (PLC-gamma), and has also been shown to activate the cytoplasmic tyrosine kinase Src. Treatment of the cells with the PKC inhibitor bisindolylmaleimide does not prevent tube formation. In contrast, Src kinase activity is a prerequisite for EC differentiation, since treatment of the cells with PP1, a Src family specific inhibitor, abrogates tube formation. In differentiating EC, FGF-2 induces complex formation between Src and focal adhesion kinase (FAK). These data indicate that the Ras pathway is initiated via Shc or FRS2, dependent on the cellular program. Blocking the function of Src family kinases, attenuates differentiation.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Induction of apoptotic cell death in vascular endothelial cells cultured in three-dimensional collagen lattice.

Endothelial cells derived from fetal bovine aorta (BAECs) undergo apoptosis in three-dimensional (3-D) type I collagen lattice in the absence of specific angiogenic factor. In the presence of angiogenic factor, BAECs survive and form a capillary-like tube structure in 3-D culture. In the present study we elucidate the mechanisms of BAECs apoptosis or survival and tube formation in 3-D culture. When BAECs embedded in collagen lattice were cultured with angiogenic factor (fibroblast growth factor-2 (FGF-2) or 4beta-phorbol 12-myristate 13-acetate (PMA)) in the presence of PD98059, a specific inhibitor of mitogen-activated protein kinase kinase, BAECs did not form tube structures and underwent apoptosis in collagen lattice. Function-blocking antibody against alphavbeta3 integrin also inhibited tube formation and induced apoptosis in 3-D culture in the presence of angiogenic factors. Exposure of BAECs to FGF-2 and PMA had no effect on the alphavbeta3 integrin expression but induced the activation of alphavbeta3 integrin. PD98059 attenuated alphavbeta3 integrin activation in response to angiogenic factor. KB-R8301, a hydroxamic acid-based matrix metalloproteinase (MMP) inhibitor, prevented apoptotic cell death in the absence of angiogenic factor in 3-D culture and enhanced capillary-like tube formation in the presence of angiogenic factor, which was not inhibited by the anti-alphavbeta3 integrin antibody. The results suggest that angiogenic factor-induced alphavbeta3 integrin activation through the MEK-ERK pathway regulates the BAEC fate between apoptosis and angiogenesis in collagen lattice. MMP derived from BAECs seems to play a key role in the release of cryptic ligands for alphavbeta3 integrin from intact collagen.

Angiogenesis Inducing Agents↗
PubMed1999

Signaling via fibroblast growth factor receptor-1 is dependent on extracellular matrix in capillary endothelial cell differentiation.

Differentiation of endothelial cells, i.e., formation of a vessel lumen, is a prerequisite for angiogenesis. The underlying molecular mechanisms are ill defined. We have studied a brain capillary endothelial cell line (IBEC) established from H-2Kb-tsA58 transgenic mice. These cells form hollow tubes in three-dimensional type I collagen gels in response to fibroblast growth factor-2 (FGF-2). Culture of IBEC on collagen gels in the presence of FGF-2 protected cells from apoptosis and allowed tube formation (i.e., differentiation) but not growth of the cells. FGF-induced differentiation, but not cell survival, was inhibited by treatment of the cells with an anti-beta1-integrin IgG. Changes in integrin expression in the collagen-gel cultures could not be detected. Rather, cell-matrix interactions critical for endothelial cell differentiation were created during the culture, as indicated by the gradual increase in tyrosine phosphorylation of focal adhesion kinase in the collagen-gel cultures. Inclusion of laminin in the collagen gels led to FGF-2-independent formation of tube structures, but cells were not protected from apoptosis. These data indicate that FGF receptor-1 signal transduction in this cell model results in cell survival. Through mechanisms dependent on cell-matrix interactions, possibly involving the alpha3beta1-integrin and laminin produced by the collagen-cultured IBE cells, FGF stimulation also leads to differentiation of the cells.

Amino Acid Sequence↗
PubMed1999

Prognostic significance of beta-microseminoprotein mRNA expression in prostate cancer.

BACKGROUND: Human beta-microseminoprotein (beta-MSP or PSP94) is a small protein secreted by prostatic epithelial cells. We recently reported the presence of low levels of beta-MSP mRNA expression and protein in most prostate cancer tissues. METHODS: Beta-MSP and mRNA expression was examined by in situ hybridization in biopsy specimens obtained from 92 patients with prostate cancer. All tissue specimens were obtained by needle biopsies prior to treatment. All patients subsequently received endocrine therapy. To estimate the influence of beta-MSP mRNA expression and three possible prognostic factors, i.e., patient age, clinical stage, and Gleason score, on time to progression under endocrine therapy, univariate and multivariate analyses were performed using Cox's proportional hazards regression model. RESULTS: Multivariate survival analysis showed that clinical stage was the strongest prognostic factor (P = 0.006) and that beta-MSP mRNA expression was the second strongest factor (P = 0.038) in 92 patients with stage B-D disease. Analysis of only 51 patients with stage D disease showed that beta-MSP mRNA expression was the only significant prognostic indicator for progression under endocrine therapy (P = 0.003). CONCLUSIONS: The presence of cells that express the beta-MSP transcript may be a novel indicator of potentially aggressive prostate cancer.

Aged↗
PubMed1999

Development and clinical application of high performance liquid chromatography for the simultaneous determination of plasma levels of theophylline and its metabolites without interference from caffeine.

A high performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of plasma levels of theophylline and its metabolites without interference from caffeine or caffeine metabolites. The method is simple and of practical use because it is applicable even to plasma samples from patients who take caffeine-containing beverages. The method was also reproducible with a coefficient of variation of less than 5% for each analyte. The levels of theophylline, determined by HPLC, were validated by their high correlation to the levels obtained by fluorescence polarization immunoassay. HPLC was used to determine theophylline levels in patients with bronchial asthma. The data revealed that the ratio of 1,3-dimethyluric acid, the major metabolite of theophylline, to theophylline concentration in the plasma was within a narrow range in most patients (0.055 +/- 0.01, n = 66), regardless of the method of theophylline administration or the time of blood sampling. Conversely, this ratio was as low as 0.027 +/- 0.005 in the patient with a long plasma half-life of theophylline. These results suggest that it may be possible to predict the plasma half-life of theophylline for each patient from a single blood sample. This may be useful when planning theophylline administration, especially in patients with abnormal theophylline metabolism.

Adolescent↗
PubMed1999

All-trans retinoic acid enhances gap junctional intercellular communication among renal epithelial cells in vitro treated with renal carcinogens.

Epidemiological and clinical studies imply that retinoids have a chemopreventative action against cancer and can suppress the growth of cancer cells. The regulation of connexin (Cx) expression by retinoids varies among tissues and organs. In this study, we investigated whether all-trans retinoic acid (ATRA) upregulates gap junctional intercellular communication (GJIC) in renal epithelial cells exposed to renal carcinogens. Madin Darby canine kidney (MDCK) cells were incubated with ATRA for 3 days, then briefly exposed to 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or renal carcinogens potassium bromate (KBrO3) and dimethylnitrosamine (DMN). ATRA increased the expression of connexin 43 mRNA and protein without affecting Cx 43 phosphorylation and prevented inadequate Cx 43 localisation caused by TPA/KBrO3 or DMN. Consequently, ATRA prevented the disruption of GJIC in MDCK cells. These data suggest that ATRA enhanced GJIC by upregulating Cx 43 expression and that ATRA might be useful for prevention of renal cell carcinoma.

Blotting, Western↗
PubMed1999

Value of contrast-enhanced magnetic resonance imaging in differentiation of hemangiomas from lymphangiomas in the oral and maxillofacial region.

OBJECTIVE: The purpose of this study was to investigate the ability of contrast-enhanced magnetic resonance imaging to differentiate hemangioma from lymphangioma in the oral and maxillofacial region. STUDY DESIGN: Contrast-enhanced magnetic resonance imaging was performed in 20 patients (21 masses: 17 hemangiomas and 4 lymphangiomas) through use of either a 0.2-T permanent system or a 0. 5-T superconductive system and spin-echo pulse sequences. RESULTS: After intravenous administration of contrast medium, enhancement was observed in all hemangiomas in areas corresponding to those with high signal on T(2)-weighted images. Unequivocally increased signal was observed in 10 masses, and slightly increased signal was observed in 7 masses. On the other hand, none of the lymphangiomas showed an enhancing mass on contrast-enhanced T(1)-weighted images. CONCLUSIONS: Although contrast-enhanced T(1)-weighted imaging may not improve delineation of masses in all cases, it can be used to differentiate between deep hemangiomas and lymphangiomas.

Adolescent↗
PubMed1999

Assessment of image quality in dental radiography, part 1: phantom validity.

OBJECTIVE: The purpose of this study was to describe and validate an image-quality phantom to be used in dental radiography for comparison of film and digitally acquired images. STUDY DESIGN: An aluminum block of 12 steps, with 7 holes in each step, was covered by acrylic blocks. This phantom was radiographed with Kodak Ultra-speed and Ektaspeed Plus films at 70, 65, and 60 kVp with the whole exposure range available. All together, 50 dental films were randomly sequenced and presented to 7 observers. The average number of perceptible holes from all steps was plotted against exposure for each tube voltage and film type, generating a modified perceptibility curve. The tentative optimum exposure level was determined from perceptibility curves in each experimental condition and compared with that determined by means of the standard aluminum stepwedge and the preset time of the x-ray machine. The density range of this phantom at the optimum exposure was compared with that of clinical dental radiographs. Validity of the phantom was evaluated according to the optimum exposure level from the modified perceptibility curves and the overall density range. Finally, the average maximum numbers of perceptible holes at the tentative optimum exposure level were compared for each tube voltage and film type. The statistical test used was a 2-way factorial analysis of variance. RESULTS: The exposure at the perceptibility curve peak approximated that obtained by means of the standard aluminum step-wedge and the time preset by the manufacturer. The overall density range at the perceptibility curve peak covered the clinical density range for each tube voltage and film type. There were no statistically significant differences between film types or among tube voltages. CONCLUSIONS: The x-ray attenuation range for this phantom seemed to approximate clinical conditions. In addition, differences in image quality could be quantitatively evaluated by means of the number of the holes seen in the phantom.

Absorptiometry, Photon↗
PubMed1999

Assessment of image quality in dental radiography, part 2: optimum exposure conditions for detection of small mass changes in 6 intraoral radiography systems.

OBJECTIVE: The purpose of this study was to compare 2 film systems and several digital intraoral systems with regard to visual image quality through use of a test phantom developed for this purpose. STUDY DESIGN: The detectors used for digital imaging were as follows: Computed Dental Radiography (CDR), Digora, Dixel, and Sens-A-Ray without scintillator layer. Two types of digital images were prepared for the observer performance test: one with original gray scales and another with contrast enhancement. Images with and without enhancement from the 4 systems were displayed to 7 observers. The change in the average number of perceptible holes was plotted against exposure, and modified perceptibility curves were created and compared with curves for the film systems. The exposure level at which the maximum number of holes was perceived was defined to be optimum. The optimum exposure levels were determined for each digital system and compared with that of the film systems. At the optimum exposure, the average maximum numbers of perceptible holes in each digital system with and without contrast enhancement were compared with the maximum numbers for the film systems. The minimum exposure levels were determined to be those at which the number of perceptible holes exceeded the number for film, and the possibility of exposure reduction was evaluated. RESULTS: All digital systems except the Digora system showed lower optimum exposures than E-speed film. In all digital images without enhancement, however, the maximum number of perceptible holes was significantly lower than that for the film systems at that exposure. With contrast enhancement, all digital systems except the Sens-A-Ray system showed visibility superior to that of the film systems. With the CDR, Digora, and Dixel systems, exposures could be further reduced by a considerable amount, with greater retention of information than was associated with film. CONCLUSIONS: Our results strongly suggest that digital systems, if properly used, can exceed film systems in the detection of small mass changes.

Contrast Media↗
PubMed1999

Vascular endothelial growth factor-C expression in human prostatic carcinoma and its relationship to lymph node metastasis.

Lymph node dissemination is a major prognostic factor in human cancer. However, the molecular mechanisms underlying lymph node metastasis are poorly understood. Recently, vascular endothelial growth factor-C (VEGF-C) was identified as a ligand for VEGF receptor-3 (VEGFR-3/Flt-4) and the expression of VEGFR-3 was found to be highly restricted to the lymphatic endothelial cells. In this report, we investigated the expression of VEGF-C and VEGFR-3 in human prostatic carcinoma tissue by using in situ hybridization and immunohistochemical staining respectively. Expression of VEGF-C mRNA in prostatic carcinoma was significantly higher in lymph node-positive group than in lymph node-negative group. In addition, the number of VEGFR-3-positive vessels was increased in stroma surrounding VEGF-C-positive prostatic carcinoma cells. These results suggest that the expression of VEGF-C in prostatic carcinoma cells is implicated in the lymph node metastasis.

Adenocarcinoma↗