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Biomedical subjects

E Bonucci

Publications and source records attributed to E Bonucci.

190 records · Page 11Linked to original sources
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Glycosaminoglycans and endochondral calcification.

Present controversy about endochondral calcification and ossification is concerned with changes in glycosaminoglycans. Some authors report a rise in amounts of glycosaminoglycans while others a fall. Cartilage was carefully sliced under microscopic control to provide samples of material from different functional zones of the developing tissues. The following zones were studied histochemically and analyzed for their content of total nitrogen, hydroxyproline, total hexosamines, uronic acid and phosphorus: the resting zone; the zone of proliferating and maturing cells; the calcifying zone, characterized by degenerating hypertrophic cells and early mineral deposition; the ossifying region, where early bone formation takes place. Serial analyses provided evidence that glycosaminoglycans increases before calcification starts. Afterwards, part of the glycosaminoglycan content is removed. This biphasic process appears to occur during the calcification of other tissues too, such as secondary bone and dentine.

Animals↗
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New knowledge on the origin, function and fate of osteoclasts.

The most recent findings on the origin, life-span and fate of the osteoclast can be summarized as follows. Osteoclasts originate from progenitor, mononuclear, lymphoid cells which reach the bone surface through the bloodstream. Osteoclasts resorb bone by secreting lysosomal enzymes and procollagenase in the osteoclast-bone interspace. The organic components of the matrix (first interfibrillary substance, then collagen fibrils) are digested in the extracellular space. Dislodged crystals and residual organic constituents are then phagocytosed and collected in cytoplasmic vacuoles where they are completely solubilized. The ruffled border and the adjacent "clear" zone constitute the resorbing apparatus, whose development is roughly proportional to osteoclast activity. Osteoclast nuclei are continuously incorporated and shed, so that individual cells are continuously renewed. This makes the life-span of the osteoclast extremely difficult to determine. The life of each individual osteoclast might theoretically continue as long as the stimulus to resorption persists and sufficient bone matrix is available. Primary abnormalities of the osteoclasts can induce pathologic skeletal changes, as in the case of osteopetrosis and Paget's disease of bone. Conversely, skeletal abnormalities may damage osteoclasts, as in the case of lead intoxication. When this happens, osteoclasts are essentially characterized by an underdeveloped ruffled border, pyknotic nuclei, detachment from the bone matrix and, finally, shrinkage and fragmentation. It is not yet known whether these changes only occur in pathologic conditions, or whether they are the alterations which lead senescent osteoclasts to death even in normal bone.

Animals↗
PubMedDate not supplied

Distraction epiphysiolysis as a method of limb lengthening. II. Morphologic investigations.

Distraction epiphysiolysis as a means of lengthening bone has been studied in sheep tibiae by histologic, histochemical and microradiographic and electron microscopic methods. The tibiae have been studied 1, 2, 3 and 4 weeks and 2, 4, 6 and 12 months after the induction of this procedure. Distraction epiphysiolysis occurs in the following stages: development of a fracture along a line dividing the maturing from the hypertrophic chondrocytes, with the formation of a hematoma between the fracture surfaces; downward displacement of the metaphyseal cartilaginous fragment and gradual resorption of the hematoma, which is replaced by fibrous tissue; elongation of the fibrous tissue; with the formation of collagen bundles oriented parallel to the tensile force of distraction; calcification and ossification of these bundles, with the formation of longitudinal and parallel bone trabeculae; development of periosteal bone, which becomes a new diaphyseal shaft. The results show that distraction epiphysiolysis actually lengthens the bone segments; bone structure is completely restored, without serious changes occurring in the soft tissues. Restoration of endochondral ossification in the epiphysis tends to be unpredictable, however, so that the procedure is reliable only in subjects that have almost reached skeletal maturity.

Animals↗
PubMedDate not supplied

[Interleukin-1 beta in the gingival tissues of patients with periodontitis: immunohistochemical data].

Interleukin-1 beta (Il-1 beta) is a cytokine which is considered to play a role in inducing the inflammatory reaction and the bone resorption that takes place in periodontal disease. With the aim of studying the presence and location of Il-1 beta positive cells in this disease, human gingival tissues from 12 patients with periodontitis and from 4 healthy control subjects were examined by immunohistochemical analysis. The cytokine was detected in all the patients having untreated periodontitis, although its content in gingival tissues revealed considerable variations among subjects. Il-1 beta was mainly localized within macrophage-like cells. Il-1 beta positive cells were not present in normal gingival tissue; however in 2 of the subjects considered normal there were few Il-1 beta positive cells in small areas of inflammation present in proximity of the dento-gingival junction.

Adult↗
PubMedDate not supplied

Relationship between ultrastructure and "pin test" in osteons.

In the 3 types commonly recognizable under the polarizing microscope (longitudinally, alternately and transversally structured osteons), the lamellar appearance of osteons in electron micrographs (EM) is due to the presence of layers of paralleloriented collagen bundles, with the orientation of the bundles changing abruptly through about 90 degrees in successive layers. On the EM scale, lamellae appear as completely independent entities. All 3 osteon types can be considered as consisting of a series of complete or incomplete lamellae. The quantities of collagen bundles in each of the 2 types of lamella--those with longitudinally or concentrically oriented bundles--is a distinctive feature determining the specific appearance of each type of osteon. This view has interesting implications as regards the nature of the factors which instruct and regulate osteoblasts in determining the cross-parallel arrangement of lamellar bone, and the specific characteristics of the various types of osteon. The mechanical properties of osteons are closely related to their structure. The highest values for ultimate dilating strength were obtained with transversally and alternately structured osteons, and the lowest values with longitudinally structured ones.

Adult↗