The relationship between bone strength and bone quality in rats fed with a low-magnesium (low-Mg) diet was examined. Twenty four-week-old male Wistar rats were divided into a control group (n = 10) and a low-Mg group (n = 10). Each group was fed with a conventional diet or a low-Mg diet (Mg, 6 mg/100 g diet) for 8 weeks, respectively. After the rats were sacrificed, bone strength, bone mineral content (BMC) and three-dimensional (3D) trabecular structure of the lumbar vertebra were measured, respectively. The results showed that the values of the BMC were almost the same between the control and the low-Mg diet groups. On the other hand, the bone strength of the low-Mg diet group was significantly lower than that of the control group (p < 0.01). 3D trabecular structure analysis showed a significant decrease (p < 0.05 or 0.01) in the trabecular structure of the low-Mg diet group as compared to the control group. These findings suggest that the bone strength in this model is not affected by the BMC but is strongly affected by the trabecular structure. The low-Mg diet model is considered to be an excellent model for examining bone quality.

Three patients, who received infrarenal aorto-iliac bifurcation grafts, complained of flaccid and insensible feeling on lower extremities immediatedly after surgery. These symptoms were supposed due, in two cases, to spinal cord ischemia or, in remaining one case, to ischemic change of the peripheral nerve, In former cases, spinal cord hypoxia might be caused by interrupted blood supply through spinal artery as it was intercepted temporarily but for about three and a half hours during surgical procedures. In the latter case, cramping of the left iliac artery lasted for five and a half hours, which might result in anoxic damage of the peripheral nerve. Hyperbaric oxygenation (HBO) at two atmospheric absolute (ATA) pressure for 75min and 3 ATA for 90min were repeated everyday for them. In all cases, almost complete sensorimotor recovery was obtained after 15 to 30 instances of HBO, which was combined with physical therapy. HBO seemed to have improved early hypoxic and edematous damages of the spinal cord or peripheral nerve. As an unfavorable complication of abdominal aortic surgery, incidence of sensorimotor disturbance of the extremities is infrequent and/or unpredictable, however, once it occurs, no effective therapeutic maneuvers were developed yet. Through these clinical data, HBO should be introduced more actively for such disorders. One of the key issues to enhance the effect of HBO is that, HBO should be introduced as soon as possible once postoperative nuerologic disorders were diagnosed.

In 1996, our medical school introduced symposium-style learning that is focused on recent advances in medical science as a regular undergraduate program for 6th-year students. The goals of this program are as follows: 1) to teach that good scientific research is essential to support high-quality medical education and medical care, 2) to have students enjoy research in a way they cannot in the ordinary curriculum, and 3) to stimulate interest in research in medical students who may become researchers in the future. Although a long-term survey is needed to evaluate the effects of this kind of learning strategy, an analysis of questionnaires showed that it was effective for the intended purposes. Today, the content of medical education has become diversified, and the social demands on medicine have changed greatly. Thus, we believe it is necessary to develop an education program separately from traditional ones that are primarily oriented to transmission of knowledge.

The purpose of this study was to investigate the fluctuation of the recovery period of autonomic nervous activity (ANA) after isokinetic exercise. Sixteen male subjects participated in this study after they turned in their consent forms.The subjects performed isokinetic knee extension-flexion exercise using BIODEX. We obtained the electro-cardiogram during the entire experiment. We calculated their heart rate (HR) and power spectral of R-R interval (LF is low frequency component, and HF is high frequency component. Both indexes were converted to a logarithm transformation as to lnHF and lnLF.) from pre-exercise period (PRE) and post-exercise period (POST).Some researchers reported that ΔlnHF of POST was lower and ΔLF/HF of POST was higher than those of PRE immediately after aerobic exercise; however, this study's results were in complete contrast.In conclusion, we found that the recovery periods after aerobic and isokinetic exercises of ANA are entirely different.

[Purpose] The effects of experimental osteoporosis on the trabecular bone structure of the mandible in cynomolgus monkeys were examined by radiological bone morphometric analysis. [Methods] Ovariectomy (OVX) was performed on twelve 10-year-old female cynomolgus monkeys, which were fed a controlled diet for 2 years. Twelve monkeys in a sham control group were fed under the same conditions. Using a microfocus tube and computed radiography, the removed mandibular bone samples were imaged by standardized magnification radiography, and two-dimensional digital imaging data were obtained. The structural parameters, such as skeletal area, perimeter, number, complexity, continuity and anisotropy, were measured using radiological bone morphometric analysis. The bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The width of the cortical bone was measured using magnified radiographic images. [Results] There were no significant differences between the OVX and the sham control groups in the skeletal structure indicated by the skeletal volume, number, width, perimeter, complexity, continuity, separation and spacing. However, there were significant differences between the two groups in the BMD of the mandibular body, cortical bone width, anisotropy and some parameters of the skeletal continuity. Among these parameters, the difference in the thinning of the cortical bone was most significant. [Conclusions] Using two-dimensional digital radiographic image data, this study suggests that the cortical bone width is more useful than the trabecular bone structure as the morphologic parameter for diagnosis of osteoporosis in the mandibular body.

To investigate the effects of experimental osteoporosis on the trabecular structure of the mandibular condyle in cynomolgus monkeys by radiological bone morphometry, ovariectomy (OVX) was performed on 10-year-old female cynomolgus monkeys, which were fed a controlled diet for 2 years. Ten sham control groups were fed under the same conditions. Using a microfocus tube and computed radiography, the removed mandibular condyle samples were imaged by standardized magnification radiography. The structural parameters were measured using radiological bone morphometric analysis. The bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The thickness of the cortical bone was measured using magnified radiographic images. The thickness of the cortical bone and the BMD in the OVX group were significantly lower than in the sham group. In the results of skeletal structure of the mandibular condyle, the trabecular structure of the mandibular condyle was markedly deteriorated in the OVX group. The trabecular structure of the mandibular condyle for the OVX group was significantly decreased, thus it was suggested that osteoporosis is a potential risk factor of osteoarthritis of the temporomandibular joint.

To develop an osseointegration analyzing system for dental implants, a new analyzing system which can assess the level of osseointegration between an implant and trabecular bone was constructed using digital radiography with morphological filter and node-strut analysis. For assessment of this system, a grayscale test chart that simulates six levels of an osseointegration was created. In addition, digital implant images were made in which the trabecular pattern around the implant was varied over a total of five levels. Implant osseointegration was evaluated on the basis of seven parameters related to the number of nodes (Nd) and terminuses (Tm) of the skeleton bound to the implant (Im) and the skeletal length. The seven parameters were as follows: the number of struts connecting the Im with the Nd and Tm (N.ImNd, N.ImTm), the total number of N.ImNd and N.ImTm (N.Im), the strut length connecting the Im with the Nd and Tm (ImNd, ImTm), and the ratios of the struts connecting the Im with the Nd and Tm (ImNd/TSL, ImTm/TSL), where TSL is the total strut length.Strong correlations (R² = 0.971-1.0) between the theoretical values from the test charts and the measured values were demonstrated. N.ImNd showed the strongest correlation, R² = 0.948, from the digital implant images, followed by N.Im and ImNd, with correlations of R² = 0.86 and R² = 0.84, respectively. This new system for evaluating implant osseointegration by applying morphological processing and node-strut analysis could be useful for computer-assisted diagnosis of digital dental implant images.

In vascular surgery, thrombo-embolism and hemorrhage are major noisome complications. We report a case of cholesterol emboli which came from atheromatous aortic wall during the thoracoabdominal aortic aneurysm operation. Micro-emboli were migrated into the capillary in the liver, kidney and small bowels, and the patient died of multiple organ failure. The histological examination showed the cholesterol emboli in micro-circulations. The other is a case of in situ thrombus formation in the posterior tibial artery during aortic surgery. The patient with combined (iliac and femoral) lesion had aorto-bifemoral bypass to get better proximal inflow. Just after the operation, we noticed his right lower extremity was pale and cold. Angiography revealed the thrombus distal to the occluded superficial femoral artery. Since the thrombus was too large to pass through any collateral vessels, it should be formed in situ. Femoro-popliteal bypass was added to the primary procedure with success.

In order to study respiratory transients during exercise, we examined breath-by-breath differences between gas exchange kinetics measured at the mouth and those estimated at the alveolar level. The gas exchange data at the mouth were obtained by measurement of expired gases only (expiratory flow method) . Correction for breath-by-breath changes in lung gas stores was applied to the total gas exchange, which was obtained by subtracting expired from inspired gas volume (alveolar gas exchange method) . Constant work loads (150, 200, 250 W) and a ramp work load (30 W/min) preceded and followed by a 50 W load were generated by a computerized cycle ergometer. Best-fit first- or second-order model values for gas exchange kinetic parameters were found by the non-linear least-squares method.
1. Regardless of work intensity and forcing function, the breath-by-breath variation in gas exchange measured at the mouth was larger than the gas exchange estimated at the alveolar level, in both a non-steady state and a steady state. The variation was caused by the invalidity of assuming zero N₂ exchange at the mouth, which was attributed to changes in lung volume.
2. Vo₂ kinetics at the alveolar level were faster than those at the mouth, while the converse held for Vco₂ at the onset of constant load work, due to the effects of fluctuations in lung gas stores on the kinetics of gas exchange at the mouth. During ramp load work, Vo₂ and Vco₂ kinetics at the alveolar level were faster than those at the mouth.
3. Steady state gas exchange values at the alveolar level and at the mouth were the same during constant load work, since the lung gas stores corrections added up to small fractions of the total gas exchange when summed over the long term.
4. Consideration of both the proper end-expiratory lung volume and ventilationperfusion inhomogeneity was required in order to estimate the true alveolar gas exchange.