Validation of a Cox prognostic model for tooth autotransplantation

OBJECTIVES

This study aimed to validate our Cox proportional hazards prognostic model for autotransplantation of teeth with complete root formation using prognostic index (PI) and determine whether the prognosis can be predicted.

PATIENTS AND METHODS

The Protocol group, as a training data set for validation, consisted of 259 autotransplanted teeth to create a PI using the Cox model, as described previously. The Pre-protocol group, as the first validation data set, consisted of 95 autotransplanted teeth treated without a protocol. The Post-protocol group, as the second validation data set, consisted of 61 autotransplanted teeth obtained after the establishment of the prognostic model. Because four prognostic factors, including history of root canal treatment (yes), number of roots (multirooted), source of donor tooth (maxillary tooth), and duration of edentulism (≥2.5 months), were selected as a Cox prognostic model, 16 patterns of PI were constructed. First, the autotransplantated teeth in the Protocol group were divided into low- and high-risk groups respectively according to the median of PI as the cutoff value. The survival curves of low- and high-risk groups were calculated using the Kaplan-Meier method and tested using the log-rank test. Then, in the Pre- and Post-protocol groups, all transplanted teeth were divided into low-and high-risk teeth by the median of PI and the survival curves of low- and high- risk teeth were analyzed statistically in a similar manner.

RESULTS

The survival curves of the low- and high-risk groups diverged significantly in the Protocol and Post-protocol groups. In the Pre-protocol group, the curves of the low- and high-risk groups were separated, and the low-risk survival rate was improved.

CONCLUSIONS

Our Cox prognostic model for autotransplantation of teeth with complete root formation was useful in predicting the prognosis by external validation using PI.

Tissue Engineering with Compact Bone-Derived Cell Spheroids Enables Bone Formation around Transplanted Tooth

BACKGROUND

Although tooth transplantation is a desirable treatment option for congenital defects of permanent teeth in children, transplantation to a narrow alveolar ridge is not feasible. In this study, we investigated the possibility of bone tissue engineering simultaneously with tooth transplantation to enhance the width of the alveolar bone.

METHODS

Bone marrow mononuclear cells or cortical bone-derived mesenchymal stromal cell spheroids were seeded onto atelocollagen sponge and transplanted with freshly extracted molars from mice of the same strain. New bone formation around the tooth root was evaluated using micro-computed tomography and histological analysis. Tooth alone, or tooth with scaffold but without cells, was also transplanted and served as controls.

RESULTS

Micro-computed tomography showed new bone formation in the furcation area in all four groups. Remarkable bone formation outside the root was also observed in the cortical bone-derived mesenchymal stromal cell group, but was scarce in the other three groups. Histological analysis revealed that the space between the new bone and the root was filled with collagen fibers in all four groups, indicating that the periodontal ligament was maintained.

CONCLUSION

This study demonstrates the potential of simultaneous alveolar bone expansion employing bone tissue engineering approach using cortical bone-derived mesenchymal stromal cell spheroids for tooth transplantation. The use of an orthotopic transplantation model may further clarify the feasibility and functional recovery of the transplanted tooth over a longer period.

Impact of the Great East Japan Earthquake and Tsunami on the Incidence of Takotsubo Syndrome Using a Multicenter, Long-Term Regional Registry

BACKGROUND

This study aimed to clarify the incidence of takotsubo syndrome (TTS) after the Great East Japan earthquake (GEJ-E) between inland and coastal areas.Methods and Results:Consecutive hospitalized patients with TTS were registered between 2009 and 2016 in Iwate Prefecture. Patients were divided into 2 groups, by whether they lived inland or in the coastal area (both max. seismic intensity, 6^-). The incidence of TTS was calculated using the standardized incidence ratio (SIR) before and after the earthquake. The long-term prognosis of the 2 groups was compared by Kaplan-Meier analysis. A total of 112 patients with TTS were registered from the acute coronary syndrome records of each hospital (n=4,163); 9 patients with TTS were registered within 2 months of the earthquake. A significant monthly variation was observed in March and April 2011 compared with the other months (P=0.029). At 2 years after the earthquake, the SIR was significantly increased in the coastal area (P<0.01), but decreased after ≥3 years. There were no significant differences in the long-term prognosis between the 2 groups (P=0.20).

CONCLUSIONS

The incidence of TTS was increased in the acute phase after the GEJ-E, particularly in the coastal area. The magnitude of the tsunami damage is presumed to be a factor in the increased incidence of TTS, even though the seismic intensity in both areas was comparable.

Gender Differences in the Circadian and Seasonal Variations in Patients with Takotsubo Syndrome: A Multicenter Registry at Eight University Hospitals in East Japan

Objective The aim of this study was to clarify the circadian and seasonal variations in addition to identify sex-based differences in Japanese patients with Takotsubo syndrome (TTS). Methods The authors conducted a retrospective observational study to analyse the differences between the groups based on sex. Patients The patients were registered out of each institute registry of the acute coronary syndrome (ACS) which contains a total of 10,622 cases in eight academic hospitals in east Japan. Results Data for 344 consecutive TTS (73 male and 271 female) were extracted from each hospital registry. In-hospital mortality was higher in the male group than in the female group (18% vs. 7%; p=0.005). With regard to the circadian variations in all study patients, TTS events occurred most often in the afternoon and least often during the night. Moreover, the patterns of circadian variations in the female and male groups were the same as that of all study patients. TTS events occurred most frequently in the autumn and least often in the spring in the whole study cohort. Moreover, the seasonal variation in the female group showed the same pattern as that of the whole cohort. However, there were no significant seasonal differences in the incidence of TTS in the male group. Conclusion In a multicenter study in Japan, seasonal variation was observed in the female group but not in the male group. Circadian variation was observed in both groups. These results suggested that the pathogenesis and clinical features of TTS might therefore differ according to sex.

Alliin inhibits adipocyte differentiation by downregulating Akt expression: Implications for metabolic disease

Obesity is currently an important health problem and is associated with an increased likelihood of various diseases. The efficacies of various natural treatments have been assessed for their utility in treating obesity. Alliin (S-allyl-L-cysteine sulfoxides) is considered the major component of garlic and has a wide range of natural antioxidant properties. However, the direct effects of alliin on obesity have not been well clarified. The present study investigated the effects and possible mechanisms of alliin on adipocyte differentiation. The 3T3-L1 cells were treated with alliin (0-40 µg/ml) during adipogenic differentiation. The effect of alliin on lipid accumulation was evaluated by Oil red O staining. Reverse transcription-quantitative PCR was performed to investigate the expression levels of adipogenic differentiation-related genes. The accumulation of lipid droplets was markedly inhibited following alliin treatment. The expression levels of multiple adipogenic transcription markers, such as CCAAT/enhancer-binding protein (C/EBP) β, C/EBP α and peroxisome proliferation-activity receptor γ, were markedly decreased following treatment with alliin during adipogenic differentiation. Expression levels of several adipocyte-related genes were subsequently suppressed. Additionally, alliin suppressed PKB/Akt and PI3K expression. These results suggested that alliin exhibits anti-adipogenic activity by downregulating major adipogenic differentiation-related genes and Akt/PI3K expression. Alliin may have a potential therapeutic effect on metabolic disease.

Additive Value of CT to Age, Aortic Diameter, and Echocardiography in Diagnosis and Classification of Bicuspid Aortic Valve in Patients with Severe Aortic Stenosis

Purpose

To develop and validate a CT diagnostic algorithm for bicuspid aortic valve (BAV) classification.

Materials and Methods

This retrospective study included 212 consecutive patients with severe aortic stenosis who underwent CT followed by aortic valve replacement (mean age, 71 years [range, 27-93 years]; 125 women; 37% with a BAV) from 2012 to 2017. BAV diagnosis and BAV category were determined by using the CT diagnostic algorithm developed and were compared with those attained through surgical diagnosis. Reproducibility and agreement were assessed using the Cohen kappa (κ) coefficient. The value of adding CT to age, aortic diameter index, and transthoracic echocardiography (TTE) was evaluated by using the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and decision-curve analysis.

Results

Intra- and interobserver reproducibility were good or excellent for all CT diagnoses (κ ≥ 0.6 for all). Agreement between CT and surgical diagnoses was excellent (κ = 0.90) for BAV detection and good (κ = 0.69) for BAV categorization. Sixteen percent (five of 31) of patients with functional BAV diagnosed by using CT received a diagnosis of congenital BAV at surgery. The addition of CT to age, aortic diameter, and TTE showed a higher AUC (with CT, 0.97 [95% CI: 0.91, 0.99] vs without CT, 0.91 [95% CI: 0.85, 0.95]; P = .003) and NRI (1.79 [95% CI: 1.65, 1.92], P < .001) and a higher net benefit among all BAV probabilities.

Conclusion

CT diagnosis was consistent with surgical diagnosis and had an additive value over traditional diagnostic methods; however, there was a risk of overlooking congenital BAV in patients with functional BAV diagnosed by using CT.Supplemental material is available for this article.© RSNA, 2021.

Impact of east Japan earthquake disaster with massive tsunami for prevalence of Takotsubo syndrome – a multicenter regional registry before and after east Japan earthquake disaster

Background

Previous studies demonstrated Takotsubo syndrome (TS) was easy provoked by earthquake disaster. However, a previous other regional report demonstrated TS was not increased after 2011 east Japan earthquake disaster. The purpose of this study was to clarify incidence of TS after the earthquake disaster in Iwate prefecture during long term period.

Method

Consecutive hospitalized TS patients were registered during 8 years between 2009 and 2016 in our medical university and five Iwate prefecture hospitals. Moreover, patients were divided into two groups, i.e., those with the inland and those with tsunami-stricken area groups. Prevalence of TS were calculated by standard incidence ratio (SIR) before and after the earthquake disaster. Moreover, long-term prognosis in the both groups was compared using Kaplan-Meier analysis.

Results

A total of 112 TS (male 25 and female 87) were registered from acute coronary syndrome registry in each hospital (n=4,163). Averaged age was 75.3 year-old. A total number of TS just after the two months of the earthquake (March and April 2011) was nine and significance monthly variation was observed comparing with the other months (p=0.029). SIR before and after the disaster is as following Figure. There were no significant differences for long-term prognosis between the two groups (p=0.20).

Conclusion

Incidence of TS was increased in acute phase after east Japan earthquake disaster. However, significance increases were maintained during long-term period, although number of TS was decreased after acute phase. TS is increased not only acute but also chronic phase after the serious earthquake disaster.

Standard incidence ratio

Funding Acknowledgement

Type of funding source: None

Sex-Related Differences in Cardiac Remodeling and Reverse Remodeling After Transcatheter Aortic Valve Implantation in Patients with Severe Aortic Stenosis in a Japanese Population

Left ventricular (LV) remodeling with aortic stenosis (AS) appears to differ according to sex, but reverse remodeling after transcatheter aortic valve implantation (TAVI) has not been elucidated in a Japanese population. This study aims to determine whether any sex-related differences in LV or reverse remodeling after TAVI exist in the context of severe AS.Of 208 patients who received TAVI for severe AS in our institution, 100 (men, 42; mean age, 83.0 ± 4.9 years) underwent transthoracic echocardiography before and 3 months after TAVI. Despite similar valvular gradients, women with severe AS had lower indexed LV mass (LVMi) than did men (152.3 ± 35.4 versus 173.2 ± 44.6 g/m², P = 0.005), with smaller indexed LV end-diastolic (LVEDVi) (50.2 ± 13.3 versus 61.4 ± 20.7 mL/m², P = 0.001) and end-systolic (LVESVi; 17.9 ± 8.7 versus 24.3 ± 13.8 mL/m², P = 0.006) volumes. After TAVI, women (-6.0% ± 14.4%) had higher reduction in the rate of change of relative wall thickness (RWT) than did men (4.4% ± 19.0%, P = 0.003). Men (-8.9% ± 3.9%) had higher reduction in the rate of change of LVEDVi than did women (1.5% ± 3.3%, P = 0.045). Incidence of LV reverse remodeling defined as a reduction in LVESV of >15% was significantly higher in men (50%) than in women (26%, P = 0.013).In addition to sex differences in the pattern of LV remodeling with AS, reverse LV remodeling after TAVI also differed between sexes.

Tooth transplantation with a β-tricalcium phosphate scaffold accelerates bone formation and periodontal tissue regeneration

OBJECTIVES

Although tooth transplantation is a useful treatment option as a substitute for a missing tooth, transplantation to a narrow alveolar ridge is not feasible. In this study, we tested a tissue engineering approach simultaneously with tooth transplantation using a scaffold or a combination with cells to accelerate bone formation and periodontal tissue regeneration.

MATERIALS AND METHODS

Bone marrow mononuclear cells (BM-MNCs) were harvested from C57BL/6J mice. The upper first or the second molar of 3-week-old C57BL/6J mice and a β-tricalcium phosphate (β-TCP) scaffold were transplanted with BM-MNCs (MNC group) or without BM-MNCs (β-TCP group) into the thigh muscle of syngeneic mice. The tooth alone was also transplanted (control group). After 4 weeks, the transplants were harvested and analyzed.

RESULTS

Bone volume was significantly larger in the MNC and the β-TCP groups than that in the control group, and the newly formed bone was observed on the lateral wall of the root. Compared with the control group, the MNC group showed a larger trabecular thickness and fractal dimension.

CONCLUSION

This study showed accelerated bone formation and periodontal tissue regeneration when tooth transplantation was performed with a β-TCP scaffold. BM-MNCs may accelerate bone maturation, while the effect on bone formation was limited.

Around 90° Contact Angle of Dish Surface Is a Key Factor in Achieving Spontaneous Spheroid Formation

Following the discovery of the primary culture of neural stem cells, the spheroid culture has been recognized as one of the selective culture methods for somatic stem cells. Since then, various methods were reported to generate spheroids, which can enrich the potent stem cell population. However, the fundamental factors affecting spheroid formation remain unclear. In this study, we focused on the surface property of the culture dishes, in particular, hydrophobicity. Primary mouse skin culture cells were prepared with conventional two-dimensional culture, and then, the cells were transferred to culture dishes with varying hydrophobicity, which was confirmed with the water contact angles. Of these, a culture dish possessing an almost 90° water contact angle was the only one that successfully exhibited spheroid formation. The spheroid formation was spontaneous, efficient, and stable. Since this outcome was achieved with a conventional culture medium with serum, but without any additives such as epidermal growth factor, basic fibroblast growth factor, and B27, the spheroid formation from this process was not affected by serum and was also not dependent on additives. The results from immunofluorescence and quantitative real-time polymerase chain reaction testing showed the expression of embryonic stem cell markers such as SSEA-1, SOX2, OCT4, and Nanog, which confirmed that the spheroids with this method are comparable to those from other methods. This outcome was reproducible and could be applied not only to skin-derived cells but also to oral mucosa-derived cells, cortical bone-derived cells, and 3T3 cells, also suggesting the generality and robustness of this phenomenon.

DEVELOPMENT OF A HIGH-EFFICIENCY PROTON RECOIL TELESCOPE FOR D-T NEUTRON FLUENCE MEASUREMENT

A high-efficiency proton recoil telescope was developed to determine neutron fluences in neutron fields using the 3H(d,n)4He reaction. A 2-mm thick plastic scintillation detector was employed as a radiator to increase the detection efficiency and compensate for the energy loss of the recoil proton within. Two silicon detectors were employed as the ΔE and E detectors. The distance between the radiator and the E detector was varied between 50 and 150 mm. The telescope had detection efficiencies of 3.5 × 10-3 and 7.1 × 10-4 cm2 for distances of 50 and 100 mm, respectively, which were high enough to determine the neutron fluence in 14.8-MeV neutron fields, with a few thousand cm-2 s-1 fluence rate, within a few hours.

Effect of Left Ventricular Assistance on Sympathetic Tone

To determine the effect of left ventricular assist device (LVAD) pumping on sympathetic tone, renal sympathetic nerve activity (RSNA) was detected in acute animal experiments.

Our TH-7B pneumatically driven, sac-type ventricular assist device was used in 7 adult mongrel dogs. RSNA was detected by the use of bipolar electrodes attached to the left renal sympathetic nerve. RSNA was amplified and integrated by use of an R-C integrator circuit. The area of the integrated nerve discharge per unit time was calculated in the computer system and expressed as RSNA per unit time.

During LVAD pumping, RSNA decreased with increase in blood pressure, with an increase in pulmonary artery flow, and with a decrease in left atrial pressure. These data suggest that LVAD has an effect on the sympathetic nervous system which is mediated by the aortic and cardiopulmonary baroreflex system.

Estimation of the following Cardiac Output Using Sympathetic Tone and Hemodynamics for the Control of a Total Artificial Heart

A sympathetic neurogram is potentially useful for the development of a real time total artificial heart (TAH) control system. We used sympathetic tone and hemodynamic derivatives to estimate the following cardiac output in acute animal experiments using adult mongrel dogs. Moving averages of the mean left atrial pressure and mean aortic pressure were used as parameters of the preload and afterload, respectively. Renal sympathetic nerve activity (RSNA) was employed as a parameter of sympathetic tone. Equations for the following cardiac output were calculated using multiple linear regression analysis of the time series data. A significant correlation was observed between the estimated and following measured cardiac output. These results suggest the potential usefulness of the sympathetic neurogram for the real time TAH automatic control system.

Vagal Nerve Activity and the High Frequency Peak of the Heart Rate Variability

For the Quality of life (QOL) of patients with an artificial heart system, monitoring an information of the cardiovascular control system may be important. We have been evaluating the autonomic nervous system for that purpose. Recently, fluctuations in hemodynamic parameters including heart rate variability (HRV) were evaluated by means of spectral analysis and nonlinear mathematical analysis. Respiratory wavers in HRV were thought ro reflect ongoing information of the parasympathetic nerve activity. Is it true? In order to confirm this hypothesis, we recorded vagal nerve activity directly in the chronic animal experiments. Six healthy adult goats were anesthetized with Halothene inhalation and thoracotomy were performed by the fourth lib resection during mechanical ventilation. Arterial blood pressure, right and left atrial pressures were continuously monitored with the catheter insertion. Cardiac output was measured by the electromagnetic flowmeter attached to the ascending aorta. After the chest was closed, incision was made to the left neck and left vagal nerve was separated. Stainless steel electrodes were inserted into the vagal nerve and fixed by the plasticizer. After the incision was closed, the goats were transferred to the cage and extubated after waking. Hemodynamic parameters and vagal nerve activity were measured in the awake condition. The results showed that clear observation of the autonomic nerve discharges were embodied by this experimental system. The vagal nerve discharges were synchronized with heart beat and respiration. The vagal nerve tonus was significantly influenced by the hemodynamic alteration. However in some condition, the respiratory wave was not always consistent with tonus of the vagal nerve activity, thus suggesting that we should check another information to evaluate the parasympathetic tone. We must continue this study to evaluate an autonomic nerve during artifical heart circulation.

Mayer Waves in Dogs with Total Artificial Heart

To assess the effect of a total artificial heart (TAH) on the autonomic nervous system a power spectral analysis of the hemodynamics in a TAH animal was done by the maximum entropy method. Two pneumatically driven sac-type ventricular assist devices were implanted as total biventricular bypass (BVB) in adult mongrel dogs to compare the differences between natural heart and TAH. Once the BVB was pumping, the natural heart was electrically fibrillated to constitute the BVB-type TAH model. In the arterial pressure waveform in animals with TAH, respiratory waves were not changed (97.7±24.6%) though Mayer waves were significantly decreased (47.5 ± 22.6%) compared with the animal with a natural heart. These results suggest that prosthetic hemodynamics in the TAH animal affect fluctuations in the cardiovascular system.

Monitoring System for the Totally Implantable Ventricular Assist System by Use of Sensors for Virtual Reality

For the development of the totally implantable artificial organs, it is an important problem to monitor the conditions of the implantable devices, especially when used in clinical cases. In this study, we used position sensors for the 3-dimensional (3-D) virtual reality (VR) system monitor an implantable artificial heart. The sensors used in the experiments were 3-space Fastrak (Polhemus, USA). The position sensors using electro-magnetic forces were attached to the inner actuating zone. Sensitivity of the position sensors was in the order of around 0.8 mm. By use of these VR position sensors, we could easily detect the six degrees of freedom as x,y,z, and pitch, yaw, roll of these sensors. Experimental evaluation using a model circulation loop and healthy adult goats was performed. Experimental results suggest that our newly developed implantable sensors for monitoring the implantable artificial heart system were useful for sensing driving condition, thus possibly useful for the implantable devices for clinical usage.

Development of Total Artificial Heart with Economical and Durability Advantages

To develop a total artificial heart (TAH) pump system, we created a design paying particular attention to durability and cost. We adopted a pneumatically driven sac type artificial heart, where the configuration of the sac was decided according to the methodology of flow visualization. Its configuration is almost round to achieve as little stagnation as possible and a low turbulent flow. The main body of the sac was made using polyvinyl chloride (PVC) paste. The paste was poured into an external mold, and heated in a hot air drying oven. Coating was performed using polyurethane. The basic performance of this pump system was tested using a model circulation circuit, and a fitting study through acute animal experiment, using a healthy adult goat, was carried out. As for the TAH produced experimentally, a pump output exceeding 5.0 l/min in the model circulation circuit was provided. Implantation in the internal pleural cavity of a healthy adult goat, 55 kg in weight, proved possible and quite easy in comparison. It is thought that a more refined design in the connector part is desirable. Furthermore, a chronic experiment with the TAH will be carried out, and examination will need to be repeated in the future.

Trabecular bone microstructure and mineral density in human residual ridge at various intervals over a long period after tooth extraction

BACKGROUND

Long-term changes of trabecular microstructure in human tooth extraction socket have not been investigated.

PURPOSE

To examine the trabecular microstructure of human residual ridges at various intervals following tooth extraction, and to determine whether bone remodeling activity can attain points of relative stability and when such points are reached.

MATERIALS AND METHODS

Forty-four bone biopsy specimens were obtained from lower molar or premolar regions of residual ridges. Postextraction times ranged from 1.6 to 360 months. Samples were analyzed using micro-computed tomography and three-dimensional bone morphometry with histological analyses. Trabecular bone parameters were plotted against postextraction times, and a stepwise piecewise linear regression analysis was performed to determine at which points of time these parameters either increased or decreased.

RESULTS

Using piecewise linear regression, "inflection points" were found in most trabecular bone parameters between 7 and 12 months postextraction. Among the residual ridge samples, woven trabecular structure became mature, consisting of thick lamellar trabeculae with sufficient bone density, under dynamic bone remodeling until the 7th to 12th month post-tooth extraction. After this period, the mature network structure remained stable with low remodeling activity.

CONCLUSION

Bone remodeling of trabecular structure in human residual ridge after tooth extraction had a stabilization period.

Can the Artificial Heart Make the Circulation Become Fractal?

In order to analyze the hemodynamic parameters in prosthetic circulation as an entity and not as decomposed parts, non linear mathematical analyzing techniques, including the fractal dimension analyzing theory, were utilized. Two pneumatically actuated ventricular assist devices were implanted, as biventricular bypasses (BVB), in chronic animal experiments, using four healthy adult goats. For the comparison between the natural and prosthetic circulation in the same animals, the BVB type complete prosthetic circulation model with ventricular fibrillation, was adopted. All hemodynamic parameters with natural and prosthetic circulation were recorded under awake conditions, and calculated with a personal computer system. Using the non-linear mathematical technique, the arterial blood pressure waveform was embedded into the return map as the beat-to-beat time series data and fractal dimension analysis were performed to analyze the reconstructed attractor. By the use of the Box counting method, fractal dimension analysis of the hemodynamics was performed. Return map of the hemodynamics during natural and artificial circulation showed fractal characteristics, and fractal dimension analysis of the arterial blood pressure revealed the fact that lower dimensional fractal dynamics were evident during prosthetic circulation. Fractal time series data is suggested to have robustness and error resistance, thus our results suggest that the circulatory regulatory system with an artificial heart may have these desired characteristics.

Strange Hemodynamic Attractor Parameter with 1/R Total Artificial Heart Automatic Control Algorithm

To evaluate the automatic control algorithm of the total artificial heart (TAH) as an entity, and not just as parts, a non-linear mathematical analyzing technique including chaos theory was utilized. Chronic experiments on the biventricular bypass type artificial heart implantation were performed in healthy adult goats after the natural ventricles were removed. Hemodynamic time series data were recorded under the awake standing condition with TAH 1/R and fixed driving. Time series data were recorded on a magnetic tape and analyzed on a personal computer system with an A-D converter. Using the nonlinear mathematical technique, the time series data were embedded into the phase space and the Lyapunov numerical method was carried out for the quantitative evaluation of the sensitive dependence on the initial condition of the reconstructed attractor. Calculation of the largest Lyapunov exponents suggested that the reconstructed attractor of the left pump output during TAH 1/R control was a larger dimensional strange attractor, a characteristic pattern of deterministic chaos. A total system indicating chaotic dynamics was thought to be a flexible and intelligent control system. Thus, our results suggest that 1/R TAH control may be suitable for the biventricular assist type total artificial heart.

A simple technique for repositioning of the mandible by a surgical guide prepared using a three-dimensional model after segmental mandibulectomy

BACKGROUND

Mandibular reconstruction is performed after segmental mandibulectomy, and precise repositioning of the condylar head in the temporomandibular fossa is essential for maintaining preoperative occlusion.

METHODS

In cases without involvement of soft tissue around the mandibular bone, the autopolymer resin in a soft state is pressed against the lower border of the mandible and buccal and lingual sides of the 3D model on the excised side. After hardening, it is shaved with a carbide bar to make the proximal and distal parts parallel to the resected surface in order to determine the direction of mandibular resection. On the other hand, in cases that require resection of soft tissue around the mandible such as cases of a malignant tumor, right and left mandibular rami of the 3D model are connected with the autopolymer resin to keep the preoperative position between proximal and distal segments before surgical simulation. The device is made to fit the lower border of the anterior mandible and the posterior border of the mandibular ramus. The device has a U-shaped handle so that adaptation of the device will not interfere with the soft tissue to be removed and has holes to be fixed on the mandible with screws.

RESULTS

We successfully performed the planned accurate segmental mandibulectomy and the precise repositioning of the condylar head by the device.

CONCLUSIONS

The present technique and device that we developed proved to be simple and useful for restoring the preoperative condylar head positioning in the temporomandibular fossa and the precise resection of the mandible.

Development of portable long counter with two different moderator materials

A portable, light-weight long counter (LC) with small dimensions was developed. This LC consists of a (3)He thermal neutron counter, a cylindrical moderator and outer shields. It was designed to have an almost flat response in a neutron energy range of 0.4 eV to 5 MeV. The portable LC has a radius of 11 cm and a length of 39 cm. Its weight was successfully reduced to 15 kg. Polystyrene was employed instead of polyethylene for the front part of the moderator in order to increase the sensitivity to low-energy neutrons. The response function calculated using the MCNP code was consistent with the results of experiments using monoenergetic neutron calibration fields.

An attempt to decrease anisotropic emissions of neutrons from a cylindrical 241Am-Be-encapsulation source

An attempt to decrease the anisotropic emissions of neutrons from a cylindrical (241)Am-Be-encapsulated X3 source was conducted with Monte Carlo calculations and experiments. The influence of metal materials and shapes of the external casing to the anisotropy factor were focussed on. Results obtained by calculations using MCNP4C implied that a light and spherical-shaped external casing decreases the anisotropic emission of neutrons. Experimental results using the spherical-shaped aluminium protection case also revealed that the anisotropy factor was close to 1.0 with wide zenith angle ranges.

Photon dose mixed in monoenergetic neutron calibration fields using 7Li(p,n)7Be reaction

The ambient dose equivalents H*(10) of photons mixed in the 144, 250 and 565 keV monoenergetic neutron fields were evaluated using measurements from an NaI(Tl) detector and calculations done using the MCNP-ANT code. It was found that H*(10) of the photons produced in the target assembly dominates the dose, particularly near the target. The H*(10) of the photons produced in other materials in the field increases with the increase in distance from the target and could not be neglected at a large distance from the target. The ratios of the H*(10) of the mixed photons to that of the monoenergetic neutrons for 144, 250 and 565 keV neutron fields, were evaluated to be below 5.5, 6.9 and 1.5 %, respectively. The ratios were calculated at calibration points between 100 and 500 cm from the target.

Lack of changes in carotid artery compliance with systemic nitric oxide synthase inhibition

Proximal large elastic arteries (ascending aorta and carotid artery) have an important role in buffering the pulsatile pressure generated from the left ventricle, which forwards continuous peripheral blood flow and protects the brain microcirculation from end-organ damage. Although compliance of distal conduit arteries (extremities' arteries) is attenuated by the nitric oxide synthase (NOS) inhibition, it is yet unknown whether compliance of proximal elastic arteries changes by the systemic NOS inhibition. To address this question, we measured central artery compliance in 17 young adults (26±1 years) who underwent intravenous infusions of N(G)-monomethyl-L-arginine (L-NMMA) or saline (placebo) on separate days. Following the systemic NOS inhibition, the mean arterial pressure (MAP), total peripheral resistance and aortic augmentation index were significantly increased. However, carotid artery compliance was not affected significantly (from 0.10±0.01 to 0.11±0.01 mm2) per mmHg) and the β-stiffness index (an index of arterial compliance adjusted for the distending pressure) tended to decrease (from 6.63±0.35 to 6.06±0.42 a.u., P=0.07). These parameters were not altered with saline infusion. Changes in the β-stiffness index tended to correlate negatively with the corresponding changes in MAP (r = -0.31, P=0.07). These results suggest that carotid artery compliance remains unchanged during the systemic NOS inhibition in spite of systemic vasoconstriction.

Autotransplantation or replantation of cryopreserved teeth: a case series and literature review

BACKGROUND

The aim of this report was to evaluate the outcome of autotransplantation or replantation of cryopreserved teeth clinically and radiographically. Donor teeth were slowly frozen in a controlled-rate freezer using 5% dimethylsulfoxide (DMSO) and 6% hydroxyethyl starch (HES) as protectants. Seven cryopreserved teeth, with duration of storage ranging from 4 to 36 months, were autotransplanted or replanted at Niigata University Medical and Dental Hospital. Endodontic treatment involving root canal debridement followed by interim root canal filling with calcium hydroxide was started 3 weeks after the operation and continued with replacement of the calcium hydroxide filling at 2-week to 3-month intervals. Three transplants showed periodontal regeneration clinically and radiographically, whereas replacement root resorption was observed in the remaining transplants. From the results, it can be concluded that cryopreserved tooth autotransplantation has potential for clinical use; however, the risk of replacement root resorption remains.

Examination of mitral regurgitation with a goat heart model for the development of intelligent artificial papillary muscle

Annuloplasty for functional mitral or tricuspid regurgitation has been made for surgical restoration of valvular diseases. However, these major techniques may sometimes be ineffective because of chamber dilation and valve tethering. We have been developing a sophisticated intelligent artificial papillary muscle (PM) by using an anisotropic shape memory alloy fiber for an alternative surgical reconstruction of the continuity of the mitral structural apparatus and the left ventricular myocardium. This study exhibited the mitral regurgitation with regard to the reduction in the PM tension quantitatively with an originally developed ventricular simulator using isolated goat hearts for the sophisticated artificial PM. Aortic and mitral valves with left ventricular free wall portions of isolated goat hearts (n=9) were secured on the elastic plastic membrane and statically pressurized, which led to valvular leaflet-papillary muscle positional change and central mitral regurgitation. PMs were connected to the load cell, and the relationship between the tension of regurgitation and PM tension were measured. Then we connected the left ventricular specimen model to our hydraulic ventricular simulator and achieved hemodynamic simulation with the controlled tension of PMs.

Detection and avoiding ventricular suction of ventricular assist devices

Continuous flow blood pumps, such as axial flow and centrifugal pumps, have been gaining interest as circulatory devices for total artificial hearts (TAHs) and a biventricular assist device (BVAD) because of their smaller size and simpler structure compared to pulsatile pumps. However, continuous flow pumps are more prone to suction of the left ventricle than pulsatile pumps are. Sudden increases in flow rate to meet changes in physiological demand, especially in the left pump, often cause ventricle suction. In this study, a control algorithm to prevent suction from occurring in the left ventricle by controlling the rotational speed of the right pump, instead of reducing the cardiac output of the left pump, was developed and investigated. The method was tested in acute animal experiments with calves. The results indicate that this proposed method is capable of preventing suction and could simultaneously maintain circulatory control. A key advantage of this control system is that flow rates can be maximized while avoiding ventricle suction conditions particularly when the circulatory system is unstable such as in a the first few days after operation.