In vivo peritoneal surface area measurement in rats by micro-computed tomography (microCT).
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Peritoneal dialysis (PD) uses the dynamic dialysis properties of the peritoneal membrane. The fraction of the anatomic peritoneal surface area (PSA) recruited is of importance for maximizing exchanges and is potentially impacted by parameters such as fill volume. We describe an in vivo assessment of the contact surface area by micro-computed tomography (microCT) using an iodinated contrast medium added to the PD fluid, a contrast agent presumed without surfactant property. In the isotropic volume (reconstructed voxel size 186 microm x 186 microm x 186 microm), the iodinated PD fluid is automatically selected, thanks to its contrast difference with soft tissues, and its surface area is computed. The method was first tested on phantoms showing the ability to select the PD fluid volume and to measure its surface area. In vivo experiments in rat consisted of microCT acquisition of rat abdomen directly after intraperitoneal administration (10 mL/100 g rat body weight) of a dialysis fluid containing 10% by volume iodinated contrast agent. Fluorescein isothiocyanate albumin was used as dilution marker. We found a strong linear relationship (R(2) = 0.98) between recruited PSA (cm(2)) and rat weight (g) in the range of 235 to 435 g: recruited PSA = (1.61 weight + 40.5) cm(2). Applying microCT with a fill volume of 10 mL/100 g rat body weight, the in vivo measured PSA was in the order of magnitude of the ex vivo anatomic PSA as determined by Kuzlan's formula, considered in most instances as the maximal surface area that can be recruited by PD fluid. This new methodology was the first to give an in vivo high-resolution isotropic three-dimensional (3-D) determination of the PSA in contact with dialysate. Its sensitivity allows us to take into account the recruitment of fine 3-D structures of the PSA membrane that were not accessible to previous 2-D-based imaging methodologies. Its in vivo application also integrates the physiological natural tensile stress of tissues. (+info)
Effect of a bonding agent on in vitro biochemical activities of remineralizing resin-based calcium phosphate cements.
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Altered functional loading causes differential effects in the subchondral bone and condylar cartilage in the temporomandibular joint from young mice.
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3D morphological measurements of dental casts with occlusal relationship using microfocus X-ray CT.
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In the diagnosis of dental occlusion, it is necessary to quantitatively measure interocclusal contacts and transfer them to a computer model. In this aspect, three-dimensional computer models of upper and lower dental casts play a significant role. In this study, we proposed a new method to measure occlusal interaction by using a microfocus X-ray CT technique. Measurement accuracy was determined as +/-0.03 mm in comparison with a coordinate measuring machine. A superimposition procedure for two sets of three-dimensional dental cast models was also established. Using the same dental cast, the standard deviation between the two sets of models was +/-0.015 mm - which was defined as measurement precision. Between an optical laser scanner and the microfocus X-ray CT system, the standard deviation measured between the two models was +/-0.05 mm. Data were acquired when upper and lower dental casts mounted on the bite impression were scanned, and then occlusal interaction, contacts, and distance distribution between the casts were visualized by a colored map on the cast models. Within the limitations of the current study, it was successfully demonstrated that microfocus Xray CT was well poised for quantitative measurement of occlusal interaction. (+info)
Fresh autogeneic, frozen allogeneic, and decalcified allogeneic bone grafts in dogs.
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In fully-grown mongrel dogs, diaphyseal ulnar defects 25 mm long were stabilised by screws and plates, and were temporarily filled with silicone rubber blocks. After eight weeks the block was replaced either by fresh autogeneic cancellous bone, allogeneic deep-frozen cancellous bone, allogeneic decalcified bone matrix, or bone matrix gelatin. After 24 weeks the implants were evaluated by radiography, histology, and measurements of new bone volume, using computer-assisted density registration on microradiographs. Only the autogeneic bone grafts led to healing in all instances. Bone regeneration in the other groups was not significantly better than in the sham group in which no graft was employed. Decalcified bone matrix proved ineffective. (+info)
Estrogen and raloxifene improve metaphyseal fracture healing in the early phase of osteoporosis. A new fracture-healing model at the tibia in rat.
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