This study was designed to investigate the extent to which an octacalcium phosphate/gelatin (OCP/Gel) composite can repair rat calvarial critical-sized defects (CSD). OCP crystals were grown with ...various concentrations of gelatin molecules and the OCP/Gel composites were characterized by chemical analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and mercury intrusion porosimetry. The OCP/Gel composite disks received vacuum dehydrothermal treatment, were implanted in Wistar rat calvarial CSD for 4, 8 and 16weeks, and then subjected to radiologic, histologic, histomorphometric and histochemical assessment. The attachment of mouse bone marrow stromal ST-2 cells on the disks of the OCP/Gel composites was also examined after 1day of incubation. OCP/Gel composites containing 24wt.%, 31wt.% and 40wt.% of OCP and with approximate pore sizes of 10–500μm were obtained. Plate-like crystals were observed closely associated with the Gel matrices. TEM, XRD, FTIR and SAED confirmed that the plate-like crystals were identical to those of the OCP phase, but contained a small amount of sphere-like amorphous material adjacent to the OCP crystals. The OCP (40wt.%)/Gel composite repaired 71% of the CSD in conjunction with material degradation by osteoclastic cells, which reduced the percentage of the remaining implant to less than 3% within 16weeks. Of the seeded ST-2 cells, 60–70% were able to migrate and attach to the OCP/Gel composites after 1day of incubation, regardless of the OCP content. These results indicate that an OCP/Gel composite can repair rat calvarial CSD very efficiently and has favorable biodegradation characteristics. Therefore, it is hypothesized that host osteoblastic cells can easily migrate into an OCP/Gel composite.
To clarify the incidence of stenotic lesions according to the coronary arterial diameter in the acute phase. we investigated 190 patients with coronary arterial lesions who underwent an initial ...coronary angiogram (CAG) less than 100 days after the onset of Kawasaki disease. The largest diameters of the major branches were measured in the initial CAGs. The diameter of the large group was > or = 8.0 mm, that of the medium group was > or = 6.0 mm but < 8.0 mm, and that of the small group was > or = 4.0 mm but < 6.0 mm. There were 121 patients in the large group, 85 in the medium group, 77 in the small group. We investigated the stenotic lesions in the follow-up CAGs and evaluated the incidence of stenotic lesions in each group by the Kaplan-Meier method. The mean interval from the initial CAGs to the latest CAG was 97 months. The incidence of stenosis at 5, 10, and 15 years in the large group was 44, 62, and 74%, respectively. In the medium group the corresponding values were 6, 20, 58%, respectively. None of the patients in the small group developed stenotic lesions. Dilatation of more than 6.0 mm produces a high probability of irreversible change in the coronary arterial wall, leading to subsequent stenotic lesions.
Abstract Octacalcium phosphate (OCP) and porcine atelocollagen sponge composites (OCP/Col) markedly enhanced bone regeneration in a rat cranial defect model. To assess clinical application, the ...authors examined whether OCP/Col would enhance bone regeneration in an alveolar cleft model in an adult dog, which was assumed to reflect patients with alveolar cleft. Disks of OCP/Col or collagen were implanted into the defect and bone regeneration by OCP/Col or collagen was investigated 4 months after implantation. Macroscopically, the OCP/Col-treated alveolus was obviously augmented and occupied by radio-opacity, and the border between the original bone and the defect was indistinguishable. Histological analysis revealed it was filled and bridged with newly formed bone; a small quantity of the remaining implanted OCP was observed. X-ray diffraction patterns of the area of implanted OCP/Col indicated no difference from those of dog bone. In the collagen-treated alveolus, the hollowed alveolus was mainly filled with fibrous connective tissue, and a small amount of new bone was observed at the defect margin. These results suggest that bone was obviously repaired when OCP/Col was implanted into the alveolar cleft model in a dog, and OCP/Col would be a significant bone regenerative material to substitute for autogeneous bone.
Abstract This study was designed to investigate whether bone regeneration by implantation of octacalcium phosphate and porcine atelocollagen composite (OCP/Col) would be enhanced if mechanical stress ...to the implanted OCP/Col were alleviated. OCP/Col discs were implanted into an arc-shaped mandibular defect in male adult beagle dogs divided into untreated, OCP/Col, and OCP/Col/Mesh groups. In the OCP/Col/Mesh group, mechanical stress towards the implanted OCP/Col was alleviated by a titanium mesh. Bone regeneration in the three groups was compared after 6 months. Macroscopically, the alveolus in the OCP/Col/Mesh group was augmented vertically more than in the other two groups. Morphometric analysis by micro-CT showed the bone volume in the OCP/Col/Mesh group was significantly greater than in the other two groups. The augmented alveolus in the OCP/Col/Mesh group consisted of outer cortical and inner cancellous structure. Histologically, the OCP/Col/Mesh-treated alveolus was augmented by matured bone tissue along the inside of the titanium mesh. The implanted OCP/Col in the OCP/Col/Mesh and OCP/Col groups had almost disappeared. These results indicated that vertical bone regeneration by OCP/Col was efficient and successful when the mechanical stress to the implanted OCP/Col was alleviated. OCP/Col should be a useful bone substitute with active structural reconstitution.
A bone defect that is not repaired with bone completely is designated a non‐union defect or a critical‐size defect. The biological mechanism that regulates the process of bone repair of the ...critical‐size defect remains unknown. The present study was designed to investigate bone repair in a critical‐size defect compared with that in a smaller or non‐critical‐size defect. Our original standardized rat calvarial bone defect model was used for the experiment. The rate of bone formation was examined with X‐ray morphometry and the bone production of osteoblasts and osteocytes was assessed by molecular histology with in situ hybridization for type I collagen and osteocalcin. Formation of repaired bone ceased within 24 weeks in both critical‐ and non‐critical‐size defects i.e. regardless of completion of the defect repair. The results suggested that osteoblasts and osteocytes cease bone formation, and the differentiation of osteoblast progenitors declines in 24 weeks. Also, bone repair proceeds from the periosteum on both sides of the parietal bone but not from the surface of the bony edge around the original defect. The results could provide useful information for clinical research on bone repair.
A series of column experiments and risk evaluation showed that preozonation was a better option to enhance the performance of soil aquifer treatment (SAT) than ozonation after SAT with respect to ...dissolved organic carbon, trace organic contaminants, and disinfection byproducts. This is a good example to show that upgrading pretreatments can be more effective than adding extra treatments after SAT, and that it is important to optimize a water reclamation system as a whole system.
Abstract The authors have reported that a scaffold constructed of synthetic octacalcium phosphate (OCP) and porcine atelocollagen sponge (OCP/Col) enhanced bone regeneration more than sintered ...β-tricalcium phosphate collagen composite or sintered hydroxyapatite collagen composite with a rat calvarial defect model. To aim for clinical application, the present study investigated whether OCP/Col would enhance bone healing in a dog tooth extraction socket model. Six adult, male, beagle dogs were used. The tooth extraction socket model was made by extracting bilateral third maxillary incisors and the subsequent removal of buccal bone. Disks of OCP/Col were implanted into one side of the model and the other side was untreated. The specimens were fixed 1 or 3 months after implantation. In radiographic analysis, the OCP/Col-treated group showed a wider range of radiopacity than the untreated control. Histologically, the OCP/Col-treated group showed more abundant newly formed bone than untreated control, and the implanted OCP was gradually resorbed. In morphometrical analysis, enlargement of the buccal alveolus in the OCP/Col group was significantly greater than in the untreated control. This study showed that implanted OCP/Col would be replaced by newly formed bone and OCP/Col implantation would enhance bone healing in a tooth socket model.
Objectives: There are two types of late coronary dilated lesions after Kawasaki disease: new aneurysms and expanding aneurysms. The development of coronary dilated lesions late after Kawasaki disease ...was investigated. Methods: Between 1978 and 2003, 562 patients with coronary arterial lesions underwent selective coronary angiography on at least two occasions. Results: Of the 562 patients studied, 17 new dilated or expanding lesions were found in 15 patients (3%, 11 boys, four girls). The time of detection of new aneurysms after Kawasaki disease ranged from 1.9–19.2 years (median 11.4 years) and their diameters ranged from 2.0–6.5 mm (median 4.4 mm). Thirteen new aneurysms occurred in vessels in which previous aneurysms had regressed and all new aneurysms were associated with localised stenosis. A new aneurysm at the bifurcation or in the branches was seen in 14 (93%) and 13 were eccentric (87%). Of two expanding aneurysms, one involved the right coronary artery in one patient and the other the left anterior descending coronary artery. One expanding aneurysm increased from 4.4 mm to 19.5 mm over 17 years, and the other expanding aneurysm increased from 10 mm to 15 mm in one year. Conclusions: Neither new nor expanding aneurysms have caused cardiac events. New aneurysms often develop as a pre-stenotic or post-stenotic dilatation secondary to localised stenosis. New and expanding aneurysms may be caused by haemodynamic factors in addition to the abnormality of the coronary arterial wall after severe acute vasculitis. Coronary arterial wall abnormalities were stenosis as well as, rarely, dilatation of the vessels in the late period. It is important to recognise that the changes of the coronary arterial wall persist late after regression of a large aneurysm.
Although the efficacy of the in vivo osteogenic capabilities of synthetic octacalcium phosphate (OCP) crystal implantation can be explained through its stimulatory capacity for the differentiation of ...the host osteoblastic cell lineage, direct evidence that OCP supports bone regeneration by osteogenic cells in vivo has not been shown. Mesenchymal stem cells (MSCs) isolated from 4-week-old male Wistar rat long bones were pre-incubated in osteogenic or maintenance medium in the presence or absence of basic fibroblast growth factor (bFGF). OCP/Collagen (OCP/Col) or collagen disks were seeded with MSCs that had been pre-incubated in osteogenic medium containing bFGF, which exhibited the highest differentiation induction, and then incubated for an additional day. The disks were implanted in critical-sized calvaria defects of 12-week-old male Wistar rats and the specimens were analysed radiographically, histologically, histomorphometrically, and by micro-computed tomography (CT) imaging at 4 and 8 weeks after the implantation. The OCP/Col·MSCs group rapidly induced more bone regeneration, even within 4 weeks, compared to the OCP/Col group without MSCs. The bone mineral density of the OCP/Col·MSCs group was also greater than the OCP/Col group. The Col·MSCs group did not exhibit prominent osteogenicity. These results indicate that OCP crystals in a collagen matrix efficiently promote exogenously introduced osteogenic cells to initiate bone regeneration if the cells are pre-treated in a suitable differentiation condition.
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