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Get PDFThe purpose of this study was to evaluate the effect of high salt intake on the mandibular bone in Dahl-lwai salt-sensitive (DS) rats. Twenty-eight 11-week-old male DS rats were divided into four groups (n=7). The control groupsreceived a normal (0.2% NaCl) diet while the experimental groups received a diet supplemented with 8.0% NaCl. The systolic blood pressure was significantly increased in the experimental groups compared to the control groups. The animals were sacrificed under ether anesthesia at the 8th week or the 22nd week of the experiment. The biochemical data in plasma and urine suggested negative calcium balance in the experimental groups compared to the control groups. The bone mineral density was significantly reduced at the 22nd week of high salt loading. Thehistomorphometric analysis suggested that the reduction of the mandibular bone volume had already started by the 8th week of high salt loading along with the increased bone resorption and the decreased bone formation, and that the improper bone remodeling balance became normalized by the 22nd week of high salt loading. In conclusion, these results indicate that a high salt intake causes not only severe hypertension but also a mandibular bone reduction in the DS rats.departmental bulletin pape
Get PDFThis study used modal analysis to evaluate the vibratory properties of cast obturator prostheses fitted with soft lining material. Three types of buccal flange bulbs were prepared: a resin (R) type; a 2 mm-thickness relined (RM) type; and a type fully relined with MOLTENO®, (M) type. A vibration generator excited the obturator, while a Laser-Doppler Vibrometer detected the vibrations at specified measurement points. Both the excitation and response signals were sent to an FFT analyzer, which calculated the frequency response functions. Then, using DAMPCAL simulation software, the decay rates and the maximum amplitudes of rest and clasp parts were calculated. Statistical analysis was performed by means of one-way ANOVA with Fisher's PLSD test. The results indicated that for impacts simulated on both the defective and non-defective sides, the R type showed a significantly higher decay rate than did the other samples (p<0.0001). When impacts were directed at the non-defective side, the R and M types showed significantly smaller maximum amplitude values than did the RM type (p<0.0001). Only the M type, however, showed significantly smaller values when impacts were directed at the defective side (p<0.0001).departmental bulletin pape
Get PDFTo elucidate a functional involvement of amino acids in the regulation of vigilance states, we investigated time-course changes of glycine (Gly), glutamate (Glu), and glutamine (Gin) in the extracellular fluid of the oral pontine reticular nucleus (PnO) in freely behaving rats by an in vivo microdialysis technique. The average concentration of Gly in dialysates collected during rapid eye movement sleep (REMS) was significantly higher than that collected during wakefulness (W) and non rapid eye movement sleep (NREMS) under perfusion with normal artificial cerebrospinal fluid (aCSF). These state-dependent changes in Gly, however, failed to occur when the PnO was perfused with Ca2+-free aCSF. In contrast, the average concentration of neither Glu nor Gln exhibited state dependency under the perfusion with normal or Ca2+-free aCSF; however, the concentrations of all three amino acids showed no consistent time-sequential changes specifically in the first three minutes from the beginning of each vigilance state. Although it is suggested that in the PnO the average concentration of Gly was higher during REMS than during NREMS and W by a Ca2+- dependent mechanism, however, time-course changes in the amino acids are complicated and other mechanisms may also be influential.departmental bulletin pape
Get PDFIn order to modulate palatal scar tissue, especially its myofibroblastic component, there is a pressing need for an in vitro model of this tissue. In the present, study we established an organ culture model of the rat palatal scar tissue. After excision of palatal mucoperiosteum, explants from the developing immature scar tissue and from the normal palatal mucosa were used to observe myofibroblasts in vivo and their maintenance in organ culture. Explants were cultured at the gasliquid interface in serum-free Waymouth's MB 752/1 medium and in a humid atmosphere containing 55% O2/5% CO2 in air at 37℃ for 3 days. Viability of the cultured explants was evaluated with morphological and histological criteria and BrdU incorporation. After organ culture, the scar tissue showed good preservation of the in vivo histology. The myofibroblasts and smooth muscle cells of the cultured scar tissues showed continuous expression of alpha-smooth muscle actin （α-SMA), mimicking the in vivo situation. In the normal tissues, only smooth muscle cells of the blood vessels expressed α-SMA. These results demonstrate that the established model provides a useful in vitro experimental tool for investigating the palatal scar tissue in general and its myofibroblasts in particular.departmental bulletin pape
Get PDFOsteoclasts resorb bone by transporting protons (H+) into the space between the cell and the bone. To investigate the roles of a sodium-hydrogen exchanger (NHE) and a vacuolar type H+-ATPase (V-ATPase) in H+ extrusion of osteoclasts attached to bone, changes in intracellular pH (PHi) were monitored in osteoclasts isolated on glass coverslips and on bone slices using a fluorescent pHi indicator. Acid-loaded osteoclasts on glass coverslips recovered their pHi in the presence of Na+. The pHi recovery was inhibited by 5-（N, N-hexamethylene) amiloride (HMA), an inhibitor of NHE, or by removal of Na+. 7-chloro-4-nitrobenz-2-oxa-1, 3-diazol (NBD-Cl), a blocker of V-ATPase, did not block the H+ transport in osteoclasts on glass coverslips. Acid-loaded osteoclasts on bone slices recovered their pHi in the absence of Na+, and this recovery was blocked by NBD-CI. In addition, neither HMA nor NBD-CI inhibited the pHi recovery in the presence of Na+. These results indicated that osteoclasts attached to bone extrude H+ by both V-ATPase and NHE and that osteoclasts attached to glass mainly extrude H+ by NHE.departmental bulletin pape
Get PDFThis paper reviews the current status and future perspectives of the artificial heart research that was started in 1957 by Akutsu and Kolff. During the 1960's, although not much progress was made in increasing animal survival time with artificial hearts, clinical applications were already made for both a ventricular assist device in 1962 and total artificial heat（TAH) in 1969 followed by a second TAH application in 1981. Both TAH applications were done as bridges to heart transplantation. Meanwhile, the animal survival time improved during the 1970's because of the availability of better biomaterials, better understanding of the circulatory system, and improvement in surgical techniques. Continuous flow pumps were also investigated during the 1970's, which demonstrated feasibility for chronically supporting circulation in healthy animals. Four permanent cases of TAH application were done early 1980's for patients who could not be the candidates for heart transplantation. Although the patients were tethered to the external drive-console, one of them survived for nearly two years. Complications due to thromboembolism and infection were the major causes of death in these patients. The patients’quality of life was questionable and the permanent application of the TAH was then stopped to make improvements in the system in terms of implantability and biocompatibility. During the 1980's, efforts were then switcthed to development of totally implantable VAD and TAH systems, which led to the first discharge of a VAD patient from the hospital in 1992. In the early 1990’s, implantable electric VADs, Novacor and ThermoCardio System (TCI), became available to support the circulation of end-stage cardiac patients until a donor heart could be found. The transplantation rate of the VAD patients ranged around 70% with the average waiting time of 80 to 100 days. The number of patients transplanted with VADs are more than 5000 and those with the pneumatic TAH exceed 200. Because of the larger size, requirement of heart valves, and complicated control mechanism of the pulsatile VADs, continuous flow pumps have been gaining popularity among clinicians. The clinical applications of the continuous flow devices have just begun, demonstrating remarkable performance in bridging to heart transplantation. In the 21st century, we will see prevalent clinical applications of various circulatory support devices from pulsatile VAD, pulsatile TAH to continuous flow VAD. These devices will be combined with genetic treatment to re-generate the myocardium and recover the failing heart. Complete recovery of the myocardium may become possible through therapy combining circulatory assist devices and biotechnology.departmental bulletin pape
Get PDFThe role of apoptpsis in the occurrence of massive or submassive liver cell death was investigated. Of liver tissues removed from 49 autopsy cases of acute hepatic failure, 26 cases were fulminant hepatic failure (FHF), 13 were subacute hepatic failure (SAHF) and the remaining 10 were acute-on-chronic hepatic failure (AoCHF). Eleven cases were associated with HBV infection, 2 with HCV, 5 with non-A non-B hepatitis, 4 with drug medication and 4 with autoimmune disorder, while the etiology of 23 cases remained unknown. Examinations by the TUNEL method and immunohistochemistry using anti-Fas, -Bax, and -Bcl-2 antibodies were conducted. Most of the FHF and AoCHF cases and half of the SAHF cases showed massive or submassive hepatic lobular injury histopathologically. TUNEL positive cells were observed frequently, and the grade of lobular injury showed significant correlation with the frequency of TUNEL-positive liver cells. Bax and Fas were expressed on the remaining liver cells, while Bcl-2 was seen on the infiltrating lymphocytes. The frequency of TUNEL-positive liver cells showed a significant correlation with Bax expression and the grades of inflammatory cell infiltration, but a poor correlation with Fas and Bcl-2 expression. The results of the present study suggested that apoptosis plays an important role in massive and submassive hepatic cell death. Fas and Bcl-2 might not be involved in the apoptosis of liver cells, but the findings suggested that Bax might play a role in inducing liver cell apoptosis, though the mechanism could not be explained.departmental bulletin pape
Get PDFThe scope of the review has been confined to behavioral researches published mainly in the past two decades especially on patient-dentist relationship, dental anxiety, communication and patients' satisfaction. In summary, it is concluded that there is not so much progress during the periodin the field of behavioral dentistry. Consequently, several recommendations are suggested for a future study of behavioral dentistry.departmental bulletin pape
Get PDFThe composition and the concentration of inorganic ions in dental plaque significantly influence the initiation and the development of dental caries through altering the degree of saturation of the aqueous phase surrounding the dental enamel. In order to know how plaque is affected by saliva, the composition and the concentration of inorganic ions in saliva and plaque fluid were investigated. The ionic concentrations of sodium and chlorine had similar values between plaque fluid and saliva. However, the concentrations of the inorganic ions such as ammonium, potassium, magnesium, calcium, and phosphate were significantly different between plaque fluid and saliva. This meant that the saliva and plaque fluid were different in its inorganic composition presumably reflected by the metabolic activity of bacteria in the plaque. On the other hand, as for the correlation coefficients between plaque fluid and saliva composition, statistically significant correlation was observed in ions such as sodium, ammonium, potassium, magnesium, and chlorine but not in calcium, phosphate, or in pH values. This was possibly due to the fact that saliva was the main source of supply of these ions. However as for calcium and phosphate, no close correlation was found possibly because they could be supplied also through tooth enamel dissolution. The discrepancy of the results with former studies on this point was speculatively explained by the difference of the plaque age used. It was considered reasonable that the pH value was independent, as it is mainly decided by the activity of the bacteria in the plaque.departmental bulletin pape