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At least 163 records · Page 9Linked to original sources
PubMed1964

CALCIPHYLAXIS: PASSIVE TRANSFER.

Rats were sensitized by mouth with dihydrotachysterol and subsequently challenged by a subcutaneous injection of ferric dextran. Mineralization at the injection site is barely detectable 17 hours after challenge. If, at this time, the challenged skin is transplanted onto a normal recipient, mineralization continues in the nonsensitized host. Sensitization is indispensable only for the initiation of the calciphylactic response and, once "triggered," the mechanism for this type of mineralization is transferable.

Calcification, Physiologic↗
PubMed2003

[Calcifications in temporal arteries -- their morphogenesis in comparison to physiological osteogenesis].

OBJECTIVE: Vascular calcification, traditionally regarded as a dystrophic process, has recently been interpreted as a bone-like biologically regulated phenomenon. Because temporal arteries which also contain calcifications are easily available from biopsies of older individuals with suspected giant cell arteritis, we studied the morphogenesis of this calcification in comparison with the development of fetal bone. MATERIAL AND METHODS: Formaldehyde fixed arteries were processed in paraffin sections and investigated by light-, transmission-, and scanning electron microscopy. The atomic composition of the calcifications was estimated by X-ray microanalysis. Fetal bone, also fixed with formaldehyde, was investigated using identical methods. RESULTS: Early calcifications are often present as focal or diffuse granular mediacalcinosis. With increasing age, calcified granules appear in association with the internal elastic membranes and progress to sheet-like calcifications. Ultrastructurally calcospherites, not rarely exhibiting the Liesegang phenomenon, are the hallmark of early calcifications. In advanced sheet-like calcification calcospherites could be detected as components of the calcified lumps. Calcospherites also appear in endochondral calcification, but are absent in calcified osteoid. The ultrastructure of calcospherites in provisional endochondral ossification differs from that in vascular calcification. Instead of corpuscles as with the Liesegang phenomenon, radial clusters of needle-like crystals resembling apatite are present. While calcospherites of the tunica media often contain a high amount of magnesium, calcified sheets as well as bone exhibited in contrast a low magnesium content. CONCLUSIONS: It is concluded that, comparable to granular mediacalcinosis of the aorta, development of calcified arteriosclerotic plaques, and Mönckeberg's disease, calcification of small muscular temporal arteries is also initially a calcospherite-dependent process. It is generally accepted that these calcified corpuscles represent remnants of calcified necrotic or apoptotic cells. In the phase of confluence with the appearance of sheet-like calcification, a low bone-like magnesium content that differs from the high amount in the isolated medial calcospherites was measured. This finding, together with the observation that calcified sheets contain calcospherites, supports the hypothesis that vascular calcification in general is different from bone formation and has to be regarded as a biphasic process initiated by the appearance of calcospherites and followed by a secondary calcifying phase with the formation of bone-like apatite that leads to rock hard lumps of calcified vessels.

Adult↗
PubMed1994

Pinhole skeletal scintigraphic manifestations of Tietze's disease.

Tietze's disease (TD) is a self-limited, non-specific, inflammatory condition of the upper costochondral junction (CCJ). Unlike in many other skeletal diseases, radiography plays a relatively minor role in TD because radiographic changes are frequently obscured by physiological costochondral calcifications. Bone scanning is a sensitive test for TD, but its specificity is low. The present study has been conducted to assess prospectively whether pinhole scintigraphy (PS) can enhance diagnostic specificity in TD. Both planar and PS bone images were obtained in seven ribs of five patients with TD. Scans alterations were analyzed and compared with the radiographic findings. Planar scans showed "hot" areas in the region of the CCJ in all seven ribs, these hot areas lacking textural patterns. However, the magnified PS images of the CCJ showed two characteristic uptake patterns: drumstick-like uptake in acute cases and C- or inverted C-shaped uptake in chronic cases. Radiographically, chondritic sclerosis could be seen when physiological chondral calcifications were minimal or absent, but was observed when the calcification was prominent. The correlation of PS and radiographic findings revealed that C- or inverted C-shaped uptake indeed faithfully reflected the inflammatory process in the CCJ, the medial border of which is concave. The further correlation of magnetic resonance and PS images of two lesions in one patient in whom histological examination was performed showed that C- or inverted C-shaped uptake is closely associated with hypervascularity of TD. Differential diagnosis between TD, fracture and metastasis is discussed.

Adult↗
PubMed1996

Evidence of structural and material adaptation to specific strain features in cortical bone.

BACKGROUND: Functionally induced strains provide epigenetic signaling for bone modeling and remodeling activities. Strain gauge documentation of the equine third metacarpal reveals a neutral axis passing through the craniolateral cortex, resulting in a narrow band of cortex loaded predominantly in tension, with the remainder of the cortex experiencing a wide range of compression strain magnitudes that are maximal in the caudomedial cortex. This predictable strain pattern provides a model for examining the hypothesis that strain mode, magnitude, and strain energy density are potential correlates of compact bone structural and material organization. METHODS: Structural and material variables were quantified in nine equine (standard breeds) third metacarpals for comparison with the in vivo strain milieu that was evaluated in thoroughbred horses. The variables quantified included secondary osteon population density (OPD), fractional area of secondary bone (FASB), fractional area of porous spaces, collagen fiber orientation, mineral content (% ash), and cortical thickness. Each bone was sectioned transversely at 50% of length, with subsequent quantification of eight radial sectors and three intracortical regions (periosteal, middle, endosteal). Linear regression analysis compared these variables to magnitudes of corresponding regional in vivo longitudinal strain, shear strain, and strain energy density values reported in the literature. RESULTS: The craniolateral ("tension") cortex of this bone is distinguished by its 30% lower FASB and with the lateral cortex exhibits 20% darker gray level (more longitudinal collagen) compared with the average of all other locations. Conversely, the remaining ("compression") cortices as a group have a high OPD, are more extensively remodeled, and contain more oblique-to-transverse collagen. The caudal cortices (caudomedial, caudal, caudolateral) are significantly thinner (P < 0.01) and have 4% lower mineral content (P < 0.05) than all other locations. Moderately strong correlations exist between collagen fiber orientation and normal strain (r = 0.752) and shear strain (r = 0.555). When normal and shear strains were transformed to their respective absolute values, thus eliminating the effects of strain mode (tension vs. compression), these correlation coefficients decreased markedly. CONCLUSIONS: Collagen fiber orientation is related to strain mode and may function to accentuate rather than attenuate bending. These differences may represent adaptations that function synergistically with bone geometry to promote a beneficial strain distribution and loading predictability during functional loading.

Adaptation, Physiological↗