Biomedical subjects

D C Rietveld

Publications and source records attributed to D C Rietveld.

4 recordsLinked to original sources

PubMed1996

4D confocal microscopy for visualisation of bone remodelling.

Until recently it was very time consuming and difficult to make three-dimensional (3D) images of newly formed bone. With the advent of confocal technologies and increased computer power, 3D imaging is greatly facilitated. In this paper we demonstrate that enhanced confocal visualisation of newly formed bone is possible when bone is labelled in vivo sequentially with two osteotropic markers (xylenol orange and tetracycline). Computer-assisted reconstruction of the confocal optical sections was achieved through the use of the CONVEX Application Visualisation System (AVS). The computerised image data provides the researcher with ample flexibility in displaying the results. It was found that CSLM combined with AVS is excellent for visualising the remodelling process in three and four dimensions, in which the fourth dimension is time. With this approach visualised bone remodelling has become possible in a manner not easily achieved by other techniques.

Animals↗

PubMed1994

Investigation of an organic delivery system for demineralized bone matrix in a delayed-healing cranial defect model.

The osteogenic potential of demineralized bone matrix (DBM) has been demonstrated in multiple animal models and clinical applications. A particulate form of DBM is generally used to fill defects because it is easily packed into a defect site without operative planning or shaping. One potential disadvantage in the use of a particulate is the migration of particles from the defect site. To stem this, glycerol was added to DBM to improve handling properties. A study was undertaken to compare two forms of DBM with glycerol, with DBM particulate and autograft in a bony defect site. The model chosen consisted of bilateral 8-mm trephine defects created in the parietal skull of 40 rabbits. Animals were sacrificed at 2 and 8 weeks. Results demonstrated both cartilage and bone induction with the three forms of DBM, with 75-90% of the linear width of the defect filled with new bone by 2 weeks. This was similar to the autograft (86%) and significantly greater than the unfilled defects (26%) at 2 weeks. The addition of glycerol to the DBM did not affect the inductive capacity, and produced a response similar to that of DBM particulate alone or autogenous bone.

Animals↗

PubMed1994

Chemical and physical properties of collagen implants influence their fate in vivo as evaluated by light and confocal microscopy.

Porcine collagen membranes having a rough and a smooth side were used for subcutaneous implantation studies in rats. Two tanning protocols were used for the membranes, a new one involving microwaving and glutaraldehyde treatment (NEWGA), and the other, a conventional method using glutaraldehyde treatment at room temperature (OLDGA). Untreated membranes (NONGA) were also implanted. Sections of the implants were examined by light microscopy and with the confocal laser scanning microscope focusing on neovascularization and incorporation of the implant. At 64 days, the smooth sides of NEWGA and OLDGA implants were not well incorporated, with scarring subjacent to the surface and dystrophic calcification of that side of the membrane. At the same time, the rough sides of the NEWGA and OLDGA were not calcified with a giant cell reaction around the porcine collagen. The best incorporation was found in the NONGA membranes with no dystrophic calcification, excellent neovascularization of all layers, and complete remodeling at day 64. After 5 months, the completely remodeled NONGA membrane still could be identified, and the NEWGA and OLDGA membranes were calcified with a giant cell reaction having a dense fibrous capsule. It is concluded that if cross-linking is deemed necessary, the microwave cross-linking method is advisable because in the early stages there is less reactive inflammation around it, and the implant surfaces should be rough with an open structure, making calcification of cross-linked collagen unlikely.

Cell Differentiation↗

PubMed1991

[The use of allogeneic bone and tendon tissue from a central bone bank].

During the period January 1989 to December 1990 the use of bone and related soft tissue allografts from our bone bank was reviewed retrospectively. Data were complete for 278 patients, who received 403 allografts in total. Forty-nine patients were transplanted with a massive deep frozen bone allograft, 41 patients received a deep frozen soft tissue allograft, while 313 units of freeze dried bone allografts were transplanted into 188 patients. Massive deep-frozen bone allografts were used mainly in patients with bone tumours, fibrous dysplasia of the neck of the femur and for revision arthroplasty. Soft tissues were used mainly for reconstruction of ruptured cruciate ligaments. Freeze dried bone allografts such as cancellous chips as well as cortical cancellous chips were used for spinal fusion, arthroplasty, treatment of pseudarthrosis, fractures, tumours and fibrous dysplasia, and in maxillofacial defects. Cancellous blocks were used specifically for spinal fusion. Demineralized cortical dust was used mainly in maxillofacial surgery.

Bone Diseases↗