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Biomedical subjects

W L Ries

Publications and source records attributed to W L Ries.

25 records · Page 2Linked to original sources
PubMed1985

A comparative study of osteoblasts: in situ versus isolated specimens.

Osteoblasts and osteoclasts are known to adhere tenaciously to bone surfaces even when the fibrous periosteal covering is removed. Brush-smear isolates and in situ, whole bone mounts of the osteogenic periosteum on the inner and outer calvarial tables of young adult rats were examined at the light microscopic level after exposing the cells by removing the fibrous periosteum. Based on staining, enzymatic activity, and overall morphology, most of the cells could be classified as osteogenic in nature. However, detailed analysis revealed that some cells exhibited certain unique morphologic appearances that suggested the existence of subpopulations or variant forms of the conventional or prototypic osteoblast. Three variant forms were the large nucleate, small nucleate, and multinucleate osteoblast-like cells, the latter with nuclear numbers ranging from 2-10. The finding of all such forms in smears, short-term cell cultures, and in situ specimens greatly lessened the probability that the unusual forms were artifactual. Phase contrast microscopic studies and sectioning of cellular isolates for study at both the light and electron microscopic levels provided additional support for the existence of the multinucleate osteoblast-like cell. The small size of these osteoblast-like subpopulations and the orientation of the cells to the commonly used plane of section of most histologic bone specimens, particularly with the multinucleate type, could explain why they had escaped earlier detection.

Acid Phosphatase↗
PubMed1984

Osteogenic periosteum esterase activity: a comparative morphological and cytochemical study of bone cells in situ on rat proximal tibiae and in smears.

Mononucleate phagocytes are presently thought to participate, along with osteoclasts, in bone resorption. Similar cells may also be precursors to osteoclasts. Esterase is a hydrolytic enzyme commonly found in most phagocytes and cells such as these have been shown to degrade bone matrix in vitro. Therefore, periosteal cells of remodeling proximal tibiae in rats were examined for esterase activity. Stain reactions were compared both in situ and in smears. Percentages of different cell types were obtained by counting cells in Wright-Giemsa-stained smears. Osteoclasts and mononucleate phagocyte-like cells made up approximately 20% of the isolated cells. Cells resembling preosteoblasts, mononucleate phagocytes, and osteoblasts stained for esterase activity with light to moderate intensity. Osteoclasts and mononucleate osteoclast-like cells were strongly esterase positive. The esterase was characterized as being type B by using nonorganophosphorus inhibitors of the various esterase types. The addition of esterase to the list of enzyme activities of cells in close proximity to osteoclasts lends further support to the hypothesis that mononucleate cells also participate in bone resorption.

Animals↗
PubMed1982

A comparative study of osteoclasts: in situ versus smear specimens.

Osteoclasts residing on rims and walls of bony concavities on remodeling proximal tibia from growing rats were examined by light microscopy following stripping of the periosteal connective tissue layer. Comparison of these cells in situ and after transfer to glass slides revealed the presence of numerous mononucleate osteoclasts, as well as typical multinucleate forms, all exhibiting a ruffled border and acid phosphatase and succinic dehydrogenase activity. Macrophage-like cells were situated adjacent to osteoclasts in situ. Osteoblasts were relatively inconspicuous. The possibility that the basic functional osteoclast unit is a mononucleate cell is discussed.

Acid Phosphatase↗
PubMedDate not supplied

Superoxide and bone resorption.

The reaction of superoxide with nitroblue tetrazolium produces an electron-dense diformazan precipitate which can be used to localize areas of superoxide production. Transmission electron microscopy was used to demonstrate that diformazan granules formed by the reaction of nitroblue tetrazolium with excess superoxide are electron dense, whereas monoformazan granules generated by hydrogen peroxide were not. On the basis of these observations, superoxide formed along the osteoclast-bone interface was localized by demonstrating the electron-dense diformazan granules between the osteoclastic membrane and the bone surface. The formation of this reaction product was inhibited by a superoxide scavenger, the deferoxamine mesylate-manganese complex (the "green" complex), confirming the specificity of the reaction product. The scavenger also inhibited bone resorption. High concentrations of superoxide generated in vitro at a neutral pH degraded osteocalcin into numerous peptide fragments, demonstrating the ability of superoxide to break peptide bonds. These studies localize superoxide production to the ruffled border space and suggest that superoxide generated at the osteoclast-bone interface is involved in bone matrix degradation.

Animals↗