The Bulletin of Tokyo Medical and Dental University最新文献

Many studies have been done of the pH values in periodontal pockets. These studies have suggested that the pH value was influenced by the condition of the surrounding tissue. Thus, the measurement of pH in the periodontal pockets would be effective data to use for diagnosis in periodontal tissue. The sensors which have been used for measuring pH had many disadvantages, however, such as large size, slow response speed, instability in chemical substances, weak physical strength, thermal drift and so on. Therefore, there have been few reliable data on the pH values in periodontal pockets. We developed a new type of pH sensor, which was designed for use in the periodontal pocket. The sensor was made by D.C. reactive sputtering of iridium oxide on solid substances. This sensor was easy to miniaturize, had quick response speed, and was stable with respect to chemical interfere, physical shock, thermal changes, and low electrical resistance. It was used in the present study to measure the pH values in the periodontal pockets of 16 subjects for 7-73 weeks. Our results showed that the pH values in the periodontal pockets differed among the measuring points and were changeable. The pattern of change was similar in the same subject. The pH value changed depending on tooth condition. The salivary pH showed no correlation with that in the periodontal pockets.

People in general obtain knowledge about AIDS through the mass media. It is interesting to know how newspapers have dealt with AIDS in recent years, since newspapers are the most important mass media. The number of articles on AIDS from 1981 to 1994 was investigated in three major Japanese newspapers (Asahi, Yomiuri, and Mainichi) which are distributed nationwide. The first article appeared in 1982, and the number of articles gradually increased to a peak (total 785 articles) in 1987 when the first Japanese female patient was reported. Then, the number of articles decreased to 116 in 1989. The number of articles on AIDS in newspapers was not correlated with the reported number of patients.

In this study, morphologic changes in brain lesions initiated by moderate lateral fluid percussion injury in rats were investigated chronologically using high-resolution magnetic resonance imaging (MRI) and histopathologic methods. Rats were subjected to moderate fluid percussion injury (average 2.80 +/- 0.48 atmospheres) over the exposed dura overlying the right parietal cortex. MRI obtained in vivo were compared with corresponding pathologic findings at 1, 6, and 24 h and at 3, 6, 14 and 80 days after injury. T2-weighted images showed scattered low-signal intensity in the injured cortex within a few hours after injury, whereas histologic findings revealed intraparenchymal hemorrhages. T2-weighted images of the ipsilateral cerebral cortex and/or corpus callosum showed a high-signal-intensity area 4 h after injury. The high-signal-intensity area became largest in size between 6 and 24 h, then declined gradually, and almost disappeared 14 days after injury. Histologic examination revealed pyknosis, retraction of the cell body of neurons with vacuolated neuropil in the corresponding regions 6 and 24 h after injury, and cystic necrosis 14 days after injury. The location and extent of these pathologic changes were depicted accurately by MRI in vivo. In the hippocampus, pyknosis and retraction of the cell body of pyramidal neurons were observed on the injured side 24 h after injury, and the number of neurons in the CA1 and CA2-CA3 regions decreased significantly on the same side by 14 days after injury. It is concluded that morphologic changes in the brain following experimental traumatic brain injury in rats are detectable in vivo by high-resolution MRI, and that MRI may be useful for the evaluation of treatment effects in experimental brain injury.

Endothelin-1 (ET-1) and human atrial natriuretic peptide (hANP) are known as vasoactive substances. In the present study, an attempt was made to evaluate the mode by which these substances are secreted in patients having severe surgical stress. Plasma ET-1 and hANP concentrations were measured in 15 patients with esophageal carcinoma who underwent subtotal esophagectomy via right-thoraco-ventrotomy (EC group) and 10 patients with gastric carcinoma who underwent total gastrectomy via ventrotomy (GC group). The volume of intraoperative hemorrhage was significantly larger and operation time was significantly longer in the EC group than in the GC group. Plasma ET-1 concentration in the EC group increased remarkably on the first operative day (1st POD), whereas that in the GC group did not. Plasma levels of hANP in both the EC and GC groups gradually increased until they peaked on the 2nd POD. The increment of plasma hANP secretion for the EC group was significantly higher than that for the GC group on the day of the operation, suggesting that ET-1 stimulated hANP in the EC group. Plasma hANP levels reached their peak values on the 2nd POD and returned to the preoperation level on the 5th POD, while PCWP did not change significantly after the surgery. Since this discrepancy between the postoperation patterns of PCWP and hANP cannot be explained by changes in the circulating blood volume, hANP secretion may be regulated by certain factors in addition to the left ventricular pressure experienced by patients receiving heavy operation stress, such as those in the EC group.

Many studies have been performed on the mandibular orthopedic repositioning appliance (MORA) as an athletic performance enhancer since the late 1970s. The concept that changing the mandibular position would increase the strength and improve the performance of subjects has been a source of controversy among various researchers. The strength of shoulder abduction and electronic activities of six muscle groups in the upper body were tested on seven subjects in this study. The normalized data for four different situations: rest position, MVC (Maximum Voluntary Contraction) in an intercuspal position, MVC with placebo, and MVC with MORA in supported rest position were analysed. Statistical analysis demonstrated that the MVC with MORA was significantly stronger than the rest position for upper appendage strength. The electronic activities of all muscle groups were significantly greater with MORA than those in rest position, and some of them were significantly greater with MORA than with either MVC or placebo situation. THe results suggested that the muscle activities of the upper appendage were increased by biting MORA in the supported rest position during the shoulder abduction performance.

Hydroxyapatite (HA)-coating by plasma spraying technique, which has been the common method used for HA coating, is not useful for coating the surfaces of porous metal implants because of difficulty in producing a homogeneous HA coating layer less than 30 micrometers. A new coating method, thermal decomposition, has been developed to obtain a dense coating layer with a thickness of 5 micrometer. In this study, the phase composition, surface morphology and adhesive strength between the coating layer and titanium substrate were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and tear-off testing, respectively. The biocompatibility of the implant prepared using this coating technique was compared with that of implants obtained using the plasma spraying technique or uncoated titanium following implantation into canine femurs. Bonding strength between the bone and implant was evaluated by pull-out testing. New bone formation was observed by light microscopy and SEM. The dense coating layer obtained by thermal decomposition ,method was found to be composed of well-crystallized HA on XRD and SEM, and exhibited high adhesive strength. The biocompatibility of the samples obtained using this coating method was superior to that of the uncoated titanium implants and comparable to that obtained using the plasma spraying technique. The thin coating layer obtained using the thermal decomposition method should be useful for coating porous implants.

The modal analysis on vibration in the human dry skull with and without mouthguards was performed in order to clarify which elasticity modulus of the material and what form of the mouthguard are best. Nine different mouthguards were prepared for this study from three materials with different elasticity moduli amd three different forms: Soft MOLTENO (registered) mouthguards of long, middle, and short forms. Regular MOLENTO (registered) mouthguards of long, middle and short forms, and Hard MOLENTO(registered) mouthguards of long, middle and short forms. Thirty-five measurement points were established on the skull. The main measurement system was composed of a 512-D Vibration Generator, LV-1300 Laser-Doppler Vibrometer, CF-6400 FFT Analyzer, PC-9821Xn personal computer, and Vibrant PC modal analysis software. The decay rate was calculated to evaluate effectiveness of the absorption of vibration of the skull with and without mouthguards when stress was put on the skull. The results showed that he skull fitted with the long and middle mouthguards made of regular MOLTENO (registered) had a higher decay rate than the skull w the mouthguard, and that the material properties of the mouthguards influenced the absorption of the skull vibration more intensively that did the forms of the mouthguards.