No abstract

The present study was designed to investigate the extent of osteoconductive property of a mechanical mixture of octacalcium phosphate (OCP) and amorphous calcium phosphate (ACP). OCP was mixed with ACP in granules that had a diameter of 300 and 500 μm, respectively, and at 25, 50, or 75 wt %. The physicochemical characteristics and the osteoconductive properties of the mixtures were compared with OCP alone or ACP alone through implantation into rat critical-sized calvaria defects for up to 12 weeks and simulated body fluid (SBF) immersion for 2 weeks. The mixtures of OCP and ACP, in particular the OCP 25 wt % and ACP 75 wt % (O25A75), had higher radiopacity compared to ACP and OCP alone. O25A75 induced greater enhancement of bone regeneration than ACP alone at 8 weeks and that than OCP alone at 12 weeks. X-ray diffraction and Fourier transform infrared (FTIR) analyses of the retrieved mixtures showed that ACP, OCP, and O25A75 tended to convert to hydroxyapatite (HA) after the implantation, while the structure of OCP remains without complete conversion after SBF immersion. Analyses by FTIR curve fitting of the solids and the degree of supersaturation of the SBF supported the observation that the existence of ACP enhances the kinetics of the conversion. Scanning electron microscopy found that the surface of O25A75 had distinct characteristics with OCP and ACP after SBF immersion. The results suggest that the extent of the osteoconduction of OCP could be controlled by the copresence of ACP most probably through the prevailing dissolution-precipitation of the surface of ACP crystals to form HA.

Using ultrasonic, we propose here a novel method of transmitting power and information to implanted medical equipment. The proposed system is composed of two piezo oscillators and has the following functions: transmission of power and control information to an implanted device, and transmission of the information acquired by an implanted device to the outside of a living body. With amplitude shift keying (ASK), 9.5 Kbps is obtained for the proposed information transmission system.

Summary Objectives : The diagnosis of acute appendicitis is difficult, and a diagnostic error will often lead to either a perforation or the removal of a normal appendix. In this study, we constructed a Bayesian network model for the diagnosis of acute appendicitis and compared the diagnostic accuracy with other diagnostic models, such as the naive Bayes model, an artificial neural network model, and a logistic regression model. Methods : The data from 169 patients, who suffered from acute abdominal pain and who were suspected of having an acute appendicitis, were analyzed in this study. Nine variables were used for the evaluation of the accuracy of the four models for the diagnosis of an acute appendicitis. The naive Bayes model, the Bayesian network model, an artificial neural network model, and a logistic regression model were used i this study for the diagnosis of acute appendicitis. These four models were validated by using the “632 + bootstrap method” for resampling. The levels of accuracy of the four models for diagnosis were compared by the error rates and by the areas under the receiver operating characteristic curves. Results : Through the course of illness, 50.9% (86 of 169) of the patients were diagnosed as having an acute appendicitis. The error rate was the lowest in the Bayesian network model, as compared with the other diagnostic models. The area under the receiver operating characteristic curve analysis also showed that the Bayesian network model provided the most reliable results. Conclusion : The Bayesian network model provided the most accurate results in comparison to other models for the diagnosis of acute appendicitis.

The present study was designed to investigate whether composite of coprecipitating octacalcium phosphate and gelatin (C-OCP/Gel) has an effect in repairing critical-sized defect of rat calvaria with oriented regenerative bone if implanted. The materials were prepared through two steps to disperse homogenous and well-elongated OCP toward long axis of the crystals in gelatin (Gel) matrix with the distinct concentration 17-44 wt %: OCP precipitates recovered from the coprecipitated with Gel molecules in aqueous solution (referred to as C-OCP hereafter) were mixed again in fresh aqueous Gel solution with various mixing ratio to form C-OCP/Gel for implantation. C-OCP/Gel disks with 9 mm diameter and 1 mm thickness after the dehydrothermal treatment was implanted in 9 mm diameter rat calvaria critical-sized defect. The histology, the histomorphometry in the regenerated bone and the quantitative analysis of the orientation of collagen with picrosirius red staining were carried out. It was found that C-OCP/Gel is capable of not only inducing sufficiently regenerative bone over 80% of the defect coupled with practically complete material biodegradation but also forming oriented bone significantly in relation to the amount of C-OCP in Gel matrix until 12 weeks after the implantation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1029-1039, 2017.