Reinforcement mechanism of dentin mechanical properties by intracanal medicaments.
(1/50)
The reinforcement mechanism of dentin mechanical properties by intracanal medicaments was investigated. The dumbbell-shaped specimens were prepared from a collagen sheet, demineralized dentin and organic dissolved dentin. After immersing the specimens in intracanal medicaments (eugenol and formocresol), the tensile test was carried out in 37 degrees C water and the Vickers hardness test was performed. The tensile strengths increased after eugenol and formocresol immersion, especially collagen and organic dissolved dentin after formocresol immersion and demineralized dentin after eugenol immersion. Thus, formocresol immersion might have reinforced the dentin tensile strength by protein coagulation, while eugenol immersion might have reinforced the dentin tensile strength by not only protein coagulation but also chelation with hydroxyapatite. However, the hardness values did not significantly change after intracanal medicament immersion. (+info)
Amplification of PCR products in excess of 600 base pairs using DNA extracted from decalcified, paraffin wax embedded bone marrow trephine biopsies.
(2/50)
AIMS: To establish a robust method of extracting DNA from paraffin wax embedded bone marrow trephine (PBMT) biopsies for the amplification of relatively long polymerase chain reaction (PCR) products. METHOD: Xylene and ethanol were used to remove paraffin wax from eight formalin fixed, EDTA decalcified PBMT biopsies and DNA extraction was performed using a Qiagen QIAamp tissue kit. The DNA samples were amplified using nine different PCR primers sets, including those used to detect chromosomal translocations (t(11;14) and t(14;18), and clonal B cell populations. A t(11;14) PCR product of approximately 600 base pairs (bp) was sequenced using dye terminator cycle sequencing. RESULTS: All eight DNA samples extracted from PBMT biopsies were amplified successfully to generate DNA fragments up to 643 bp in length. Chromosomal translocations and immunoglobulin gene rearrangements were detected by PCR in some of the samples. Sequencing of the t(11;14) PCR product demonstrated the presence of chimaeric sequences, which included both bcl-1 and immunoglobulin heavy chain (IgH) gene sequences, consistent with the presence of this translocation. CONCLUSIONS: This method enables PCR analyses of PBMT biopsies that were not previously possible, offering the prospect of improved accuracy of diagnosis and the monitoring of patients with bone marrow disease. (+info)
Observations on the induction of bone in soft tissues.
(3/50)
Using bone decalcified with 0-6 N hydrochloric acid as an inducing agent, the inductive capacity of different soft tissue sites was investigated. Muscle and fascia regularly permitted the induction of bone, while spleen, liver and kidney suppressed bone induction. Bone formation could be induced in these organs if living autologous fascia was implanted together with the inducing agent; while bone formation was inhibited when living autologous spleen tissue was implanted with the inducing agent to normally favourable sites. The administration of systemic heparin and the diphosphonate ethane-1-hydroxyl, 1-diphosphonic acid (EHDP) suppressed bone induction. It is suggested that for bone induction to occur in soft tissues, three conditions must be present: 1) an inducing agent; 2) an osteogenic precursor cell; and 3) an environment which is permissive to osteogenesis. The presence of osteogenic inhibitors in spleen, liver and kidney is postulated. (+info)
Bone induction in implants of decalcified bone and dentine.
(4/50)
The fate of decalcified bone and dentine implanted in muscle and beneath the kidney capsule has been studied in young rats. Quantitatively speaking there was a great deal of variation, but in general the implants became surrounded and invaded by young vascular connective tissue; then tunnels were eroded and cavities enlarged by multi-nucleated giant cells; then the matrix around erosion chambers became recalcified; and finally new bone was induced on the eroded recalcified surfaces. Erosion was much more extensive, and bone was much more readily induced in the intramuscular than in the subcapsular implants. It is concluded that the presence of an eroded, recalcified surface is a pre-requisite for bone induction under these conditions. (+info)
The development of vertebral bone marrow of human fetuses.
(5/50)
The development of the bone marrow of the thoracic vertebrae in seven human fetuses ranging from 95 to 150 mm in crown-rump length (CRL) was studied using light and electron microscopy. In the 95-mm CRL, hypertrophy of the chondrocytes occurred in the central region of the vertebrae, and blood vessels penetrated there from dorsal and ventral sides of the vertebral body. The primary marrow was represented by liberated cartilage lacunnae, occupied by the thin-walled blood vessels and a few mesenchymal cells and mononuclear cells containing granules or vacuoles (GMC). In the 99-mm CRL, chondroclasts were active in removing the cartilage near the central region of the vertebrae. Consequently, a large cavity was formed and occupied by a dilated sinus. GMC were numerous. Osteoblasts and osteocytes were increased in number. Reticular cells with long processes containing large amounts of glycogen began to appear in the extravascular space and formed the loosely arranged cellular meshwork of the hematopoietic compartment. Bundles of collagen fibrils were scattered in the meshwork. Hematopoietic cells were recognizable only in the 105-mm-CRL fetus and increased in number in the 120-mm-CRL fetus. The sinus endothelium was very thin and continuous without apertures except where blood cells crossed the wall. The developing blood cells lying against the outside of the sinus endothelium indented it. At points, collagen fibrils attached to the outside of endothelial cells and appeared to function as the anchoring filaments of lymphatics. The physiologic implications of the association of stromal cells, vascular sinuses, and hematopoietic cells are discussed in relationship to the microhematopoietic environment of the bone marrow. (+info)
Regeneration of blood-forming organs after autologous leukocyte transfusion in lethally irradiated dogs. I. Distribution and cellularity of the bone marrow in normal dogs.
(6/50)
Marrow cellularity in adult beagles (1-2 yr old) is highest in centrally located bones, with values between 8000 and 12,000 nucleated cells per sq mm. It decreases gradually towards the peripheral parts of the body, reaching values below 1000 per sq mm in bones distal to the elbow and knee. The first tail segment always contains some active marrow. The fifth segment has only stromal elements. In spongy bones fat cells appear to be distributed at random among the blood-forming elements. In the middle part of the femur the fatty marrow predominates in the center of the cylinder, while the subendosteal area is very cellular. The proximal and distal ends of the femur are more cellular than the middle. The small standard deviation of the cellularity in the spongy bones of the trunk and in the proximal and middle part of the humerus makes these sites areas of choice for quantitative studies of marrow regeneration. The large variations in cellularity of the marrow in the radius and tibia of young adult dogs make these sites unsuitable for such studies. The distribution of active and fatty marrow in dogs is similar to that of humans. The differential count of active marrow is quite constant between different dogs and in the various sites of each animal. (+info)
Optimization of perfusion decalcification for bones and joints in rats.
(7/50)
Decalcification of osseous tissues by perfusion of decalcifying solution into the vascular system has never been applied to the study of peripheral joints. To optimize perfusion methods, rats were decalcified by direct immersion or by one of two perfusion techniques: 1) systemic perfusion circulating the decalcifying solution from the ascending aorta; and 2) regional perfusion circulating the solution to the lower extremities from the abdominal aorta. The process of decalcification was monitored by serial radiographic examinations. After decalcification, bone and joint samples were stained for histochemistry and immunohistochemistry. With systemic perfusion, the decalcification time, dependent on weight, was markedly reduced compared to immersion. Regional perfusion decalcification was faster than all other methods studied. Microstructural preservation was comparable and immunostaining quality often improved. Applications of this work will improve the study of basic skeletal and articular problems. (+info)
Immunohistological study of entheses in spondyloarthropathies: comparison in rheumatoid arthritis and osteoarthritis.
(8/50)
OBJECTIVE: To determine which inflammatory cell types are present in entheses from patients with spondyloarthropathy (SpA) compared with patients with rheumatoid arthritis (RA) or osteoarthritis (OA). METHODS: Enthesis specimens were obtained during orthopaedic procedures in eight patients with SpA, four with RA, and three with OA. After decalcification, the lymphocyte subsets (CD3, CD4, CD8, CD20) in the bone marrow component of each enthesis were measured by an immunohistochemical technique. RESULTS: Oedema and an inflammatory infiltrate were present in all the SpA specimens, being clearly predominant in the bone marrow component of the entheses. The density of all cell types in the bone marrow was significantly higher in the SpA group than in the two other groups. The cell type CD3+ showed the greatest difference between the SpA and RA groups, being increased fivefold in the SpA group. Within the SpA group, CD3+ cells were considerably more numerous than CD20+ cells-a difference from the RA group-and the predominant T cells were CD8+. CONCLUSION: Persistent oedema with an inflammatory infiltrate composed predominantly of CD8+ cells was noted in the entheses of patients with SpA, being predominant in the bone marrow. These results suggest that CD8+ cells may have a key role in local inflammation in SpAs. (+info)