The Bulletin of Tokyo Dental College
Print ISSN : 0040-8891
Volume 42, Issue 4
Displaying 1-6 of 6 articles from this issue
Original Articles
  • TAIHEI TANAKA, YUZURU KANEKO
    2001 Volume 42 Issue 4 Pages 201-210
    Published: 2001
    Released on J-STAGE: April 13, 2006
    JOURNAL FREE ACCESS
    The viability of dental pulp depends largely on regional blood flow, as in other organs. Measurement of absolute pulpal blood flow (PBF) and comparisons with blood flow in other organs allow the prediction of microvascular regulation in dental pulp. In previous studies, PBF was measured in dogs mainly with radioactive microspheres. However, this established technique is inaccessible to many investigators due to concerns over radiation safety and radioactive waste. To overcome these limitations, a new method has been introduced that involves the use of nonradioactive colored microspheres for measuring regional blood flow in the myocardium and in other organs in animals. However, no previous studies have investigated the use of this method to measure PBF in dogs. We attempted to determine whether blood flow in dental pulp, which comprises a small amount of the total tissue in dogs, could be measured using this technique by comparing the measured values with those for regional myocardial blood flow. Mean blood flow values were between 0.148 and 0.182ml/min/g for dental pulp at four different sites and about 1.0ml/min/g in regional myocardium. These values are comparable to those previously reported using radioactive microspheres. As nonradioactive colored microspheres safely permitted measurement of absolute PBF in dogs, this technique appears to be useful for research into microvascular blood flow in dental pulp.
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  • NOBUHARU YAMAMOTO, HIROYASU NOMA, TAKAHIKO SHIBAHARA
    2001 Volume 42 Issue 4 Pages 211-223
    Published: 2001
    Released on J-STAGE: April 13, 2006
    JOURNAL FREE ACCESS
    Frequent allelic imbalances, including loss of heterozygosity (LOH) and microsatellite instability (MSI), have been found on the long arm of chromosome 21 (21q) in several types of human cancer. This study was designed to identify the tumor suppressor locus (or loci) associated with oral squamous cell carcinoma (SCC) on 21q. In order to understand the details of genetic alterations on chromosome 21, we performed polymerase chain reaction analysis of microsatellite polymorphisms corresponding to ten loci on this chromosome. We examined forty primary tumor tissues, forty corresponding normal tissues, and seven lymph node metastatic tissues. We identified novel tumor suppressor loci in this region in primary oral SCCs. To further determine the role of 21q deletions in oral cavity carcinogenesis, forty oral SCCs were examined for allelic imbalances (LOH or MSI) at 21q using ten microsatellite markers. Among these forty patients, twenty-six (65%) showed LOH at one or more loci. Deletion mapping of these tumors revealed four discrete, commonly deleted regions on the chromosome arm. Furthermore, we detected MSI in seventeen of those tested cases (42.5%). We compared our results with the clinicopathologic features. A number of sites displaying LOH at 21q could be detected in early stage lesions, and the frequencies of LOH tended to be higher in later clinical stages, but no statistical correlation was observed. Our results strongly suggest that allelic imbalances on 21q are involved in the development of oral SCC and that at least four different putative tumor suppressor genes contributing to the pathogenesis of this disease are present on 21q. Furthermore, allelic loss on 21q appears to be a useful indicator for evaluating the malignancy and prognosis of oral SCC, because the LOH of recurrent cases was more frequent than that of non-recurrent ones.
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  • KENICHI MATSUZAKA, MASAKI SHIMONO, TAKASHI INOUE
    2001 Volume 42 Issue 4 Pages 225-234
    Published: 2001
    Released on J-STAGE: April 13, 2006
    JOURNAL FREE ACCESS
    The purpose of this study was to investigate the characteristics of new bone formation during guided bone regeneration (GBR) using immunohistochemistry and confocal laser scanning microscopy. e-PTFE membranes were applied to defects created in the tibiae of rats, and some animals were sacrificed 6, 8, or 10 days later. Serial paraffin sections were cut, stained with H-E, and examined to analyze the ratio of new bone formation. Immunohistochemical staining with a monoclonal antibody specific for PCNA was used to evaluate the proliferating activity. In other experimental rats, calcein was injected at 6, 8, and 10 days after the surgery, and the animals were sacrificed 48hr after injection. Their tibiae were removed, and Villanueva bone staining was performed before observation using confocal laser scanning microscopy to investigate the mineralization of new bones. The bone occupation ratio increased day by day, but the experimental groups had significantly higher ratios than control groups (without membrane) at each of the time periods. However, PCNA positive cells decreased over time in all groups, and there were no significant differences among the groups. Mineralization occurred more rapidly in the experimental groups than in the control groups. These results suggest that GBR accelerates the migration of osteogenic cells, the formation of new bone, and mineralization in the defect created by the e-PTFE membrane.
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  • TAKAYUKI ENDOH, MINAKO ABE, TAKASHI SUZUKI
    2001 Volume 42 Issue 4 Pages 235-241
    Published: 2001
    Released on J-STAGE: April 13, 2006
    JOURNAL FREE ACCESS
    The calcium ion influx through voltage-dependent calcium channels (VDCCs) has a vital role in the control of neurotransmitter release and membrane excitability. Prepulse facilitation is a phenomenon in which a strong depolarizing pulse induces a form of the VDCCs that exhibits an increased opening probability in response to a given test potential; this persists for several seconds after repolarization. It has been reported that prepulse facilitation occurs via dissociation of the guanosine triphosphate (GTP)-binding proteins (G-proteins) from the VDCCs and that recovery from facilitation involves rebinding of the G-proteins. The heterotrimeric G-proteins act as switches that regulate information processing circuits connecting cell surface G-protein-coupled-receptors to a variety of effectors. In this study, we have studied the characterization of G-protein subtypes in prepulse facilitation of VDCCs currents (ICa) in hamster submandibular ganglion (SMG) neurons, using whole-cell patch clamp recordings. Under control conditions, with GTP (0.1mM) in the recording pipette, the rate of prepulse facilitation was 19.0±1.9% (n=13). Intracellular dialysis with GDP-β-S (0.1mM), G-protein blocker, and pretreatment of neurons with N-ethylmaleimide (NEM) (100μM for 2min), Gi/o blocker, attenuated the rate of prepulse facilitation. Intracellular dialysis of anti-Gq/11-antibody did not alter it. These results suggest that prepulse facilitation of VDCCs is due to Gi/o-types of G-protein, but not to the Gq/11-type, in SMG neurons.
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  • HIROSHI SANO, KEN-ICHIRO SHIBASAKI, TAKASHI MATSUKUBO, YOSHINORI TAKAE ...
    2001 Volume 42 Issue 4 Pages 243-249
    Published: 2001
    Released on J-STAGE: April 13, 2006
    JOURNAL FREE ACCESS
    We examined the effects of four kinds of chitosan derivatives on initial adherence of oral bacteria onto human anterior teeth surfaces. The buccal surfaces of anterior teeth were used as the experimental surfaces. They were divided into five rectangle areas with outer dimensions of about 2mm×4mm. After applying two ml of a sample solution onto the tooth surfaces, an examiner wiped each rectangle area with a sterilized plastic swab one, three and six hours later. Then we measured bacterial counts in sterilized swabs with mitis salivarius agar.
    We found that the order of magnitude of the inhibitory effect on the adherence of oral bacteria was low molecular chitosan>phosphorylated chitosan>amorphous chitosan>carboxymethyl chitosan. The solution containing 0.5% low molecular chitosan depressed the bacterial adherence to the same extent as a 50 ppm chlorhexidine digluconate solution for three hours, and 0.1% phosphorylated chitosan also exhibited an inhibitory effect in bacterial adherence for one hour. Amorphous chitosan had a moderate inhibitory effect, but no clear inhibitory activity was found with 0.1% carboxymethyl chitosan. These results suggest that low molecular chitosan and phosphorylated chitosan have the potential to effectively inhibit the initial adherence of oral bacteria onto human tooth surfaces.
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  • HIROSHI SANO, KEN-ICHIRO SHIBASAKI, TAKASHI MATSUKUBO, YOSHINORI TAKAE ...
    2001 Volume 42 Issue 4 Pages 251-256
    Published: 2001
    Released on J-STAGE: April 13, 2006
    JOURNAL FREE ACCESS
    This clinical investigation examined the effect of phosphorylated chitosan rinsing on plaque development and on the buffering capacity of plaque suspension. Three male adult subjects participated in the trial that was designed as a single blind study. Participants refrained from mechanical oral hygiene procedures during a four-day study and rinsed three times a day with 20ml of test solutions. A wash-out period of three days was instituted between the placebo and phosphorylated chitosan rinsing period. Clinical evaluation and plaque sampling were performed at the end of each test period. We disclosed plaque accumulations on the buccal upper front teeth with a two-tone disclosing agent to distinguish between newly formed plaque and old plaque. After taking color slides, we then used a computerized image analysis. Tooth areas covered by plaque on the color slides were digitized and expressed as percentages of the tooth area. The buffering capacity of the collected plaque fluid was determined by using a β-titrator. A mouth rinse containing 0.5% phosphorylated chitosan significantly reduced both newly formed plaque areas (red disclosed; p<0.001) and old plaque areas (blue disclosed; p<0.01) compared to a placebo rinsing. However there was no significant difference in the plaque buffering capacity (p>0.05) between the mouth rinse containing 0.5% phosphorylated chitosan and placebo. These findings might suggest that mouth rinse containing phosphorylated chitosan would be effective in reducing plaque formation and have a slight ability to enhance plaque buffering capacity.
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