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Biomedical subjects

A Dhem

Publications and source records attributed to A Dhem.

At least 73 records · Page 4Linked to original sources
PubMed1984

Histological and microradiographical study of Crouzon's disease.

A histological and microradiographical study of thin undecalcified sections from the cranial vault of three different cases of Crouzon's disease has been performed. The fundamentally abnormal aspects of the bone tissues observed in this disease consist of a premature closing of the sutures, an external membranous bone apposition and an internal selective bone resorption leading to the production of the crests already visible in the clinical radiographs. A thickening of these crests by secondary bone apposition has been observed. The bone fragment removed in a fourth case during a second surgical treatment, when studied by the same technique, showed apparently normal bone.

Bone Resorption↗
PubMed1984

Bone vitality in induced radionecrosis of the mandible estimated by osteocytic population counting.

To understand the changes of the irradiated mandibular bone, we tried to define, in space, how the lesions of the osseous tissue appear and involve. We estimated the vitality of the removed jaw fragments by counting the number of inhabited lacunae (I.L.) and empty lacunae (E.L.) in the sections, without previous decalcification, after surface staining with methylene blue. The results, expressed as percentages of the total amount of osteocytes lacunae, have been compared with the microradiographic aspect of the sections. The most paradoxical finding is that the highest percentages of osteocytes appear in the most destroyed areas. As a conclusion, one may wonder how to proceed to avoid the radiotherapy being followed by attempts for repair: attempts which, indeed, are the source of the complications.

Aged↗
PubMed1983

Contribution to the histological and microradiographic study of the craniostenosis.

The authors describe the microradiographical and histological aspects of ill sutures in cases of trigonocephalies, brachycephalies and oxycephalies. This is based on the study of fragments coming from 30 cases of craniostenosis. They question the responsibility of the dura mater and invoke an encephalic cause producing by error forces at the level of the sutural areas. They also stress the absence of chondroid tissue at this particular level.

Adult↗
PubMed1980

The effects of nandrolone decanoate on rarefying bone tissue.

The effects of nandrolone decanoate on rarefying bone tissue were studied with the aid of microradiography and fluorescence microscopy in tetracycline-labelled preparations of the rabbit calcaneus and the long bones of old dogs. Osteoporosis was induced in the rabbit calcaneus by resecting of the Achilles tendon. In 20 of the 24 rabbits treated with nandrolone decanoate, the osteoporosis observed was less severe than in 8 untreated controls. Furthermore, in comparison with the controls, the signs of active osteogenesis in the treated groups increased systematically. In the old dogs, nandrolone decanoate caused a new opposition, identified by tetracycline labelling, to appear at the periphery of the medullary cavity. All the observations suggest that nandrolone decanoate has a favourable effect on osteogenetic phenomena and probably an inhibitory action on bone resorption. Consequently, nandrolone decanoate is capable of preventing or, at least, of partially correcting losses of bone mass.

Animals↗
PubMed1979

[Role of the condylar cartilage in mandibular growth (author's transl)].

Our purpose is to bring a contribution to a better understanding of the role played by the condylar cartilage in children's mandibular growth. In the newborn, microradiographical analysis of frontal (fig. 1, 2 and 3 A) or sagittal sections (fig. 4 A) has been used to locate trabecular bone of endochondrial origin. This trabecular bone contains islets of calcified cartilage easy to identify in the microradiograph (fig. 3 B) or in the section itself after methylen blue staining (fig. 4 B) and resulting from the activity of the condylar cartilage (fig. 4 C). At four month of age, the condylar cartilage is still in activity (fig. 5 A and 5 B). From both morphological and physiological points of vue, this work leads to suggest that the condylar cartilage must be compared to a growing epiphyseal nucleus or to a so-called infertile extremity of a small long bone rather than with a true growing cartilage.

Cartilage↗
PubMed1978

[Significance of the haversian number].

The aim of this work is to show that the measurement of the haversian number, i.e. the number of haversian canals per unit surface in transverse sections of compact bone, is not suffisantly accurate to determine the degree of compact bone remodelling. At the beginning of adult life, the aspect of the interstitial bone indicates that one haversian canal can correspond to one to four osteons (fig. 1). With increasing age, the diameter of the osteons decreases (fig. 2) and, consequently, for a same remodelled surface of bone the number of haversian canals varies greatly. In the elderly, the dissociation between osteon production and that of haversian canals increases (fig. 3). Moreover, the presence of large, irregular cavities which are difficult to assimilate to one or more haversian canals tends also to diminish, in terms of remodeling, the significance of the haversian number.

Adolescent↗
PubMed1976

Bone in dermatosparaxis. I. Morphologic analysis.

Normal (N-) calf bone consists of lamellae regularly spaced and oriented parallel to the periosteum. The lamellae increase in thickness from the periosteum to the medullary cavity, by apposition of layers of cells and a calcifying matrix on either side of a hypercalcified primer. In the dermatosparactic (D-) bone, the hypercalcified primer is barely visible and the cells are irregularly arranged within the lamellae. The poorly defined vascular spaces are partly filled with an acellular calcified material. In the D-bone, the collagen fibers are sparse and radiate from the vascular space, while in the N-bone they are abundant and laid down concentric with the blood channels. In the D-bone, only a few weeks old, the outer lamellae are radially oriented with respect to the medullar cavity, while haversian remodeling already occurs in the inner part of the diaphysis. At 6 months, the inner half of the diaphysis is made up of normal haversian secondary bone, while the outer half is made up of radial lamellae. The alteration of the mechanical properties of procollagen fibers in the D-bone might be responsible for its defective organization. A resistant fibrous framework, therefore, seems required to ensure the spatial organization of the cells in the calcifying matrix and to maintain its cohesion.

Age Factors↗
PubMed1976

Tetracyclines, doxycycline and calcified tissues.

The use of radioactive isotope techniques has led to a thorough re-assessment of our knowledge of bone histology. It is known that tetracyclines faithfully follow the pattern of calcium metabolism in the body. Fluorescence microscopy, after double labeling with tetracyclines and alizarin red S, is very useful for collection of qualitative and quantitative data on compact and spongy bone remodeling. Two illustrations are presented which demonstrate how oxytetracycline and doxycycline administered in therapeutic doses to growing dogs, become deposited in the dentine. The significance of these findings is discussed.

Animals↗
PubMed1975

[Notes on osteoclastic resorption].

Microradiography of transverse sections in diaphyseal compact bone of old dogs shows many osteons with irregularly delimited haversian canals, very similar to a resorption cavity (fig. 1). Microradiography of longitudinal sections in the same material reveals that the enlargement of the canal affects only a fraction of its length (fig. 2). After methylene blue staining, no osteoclasts have been observed but only small mononucleated cells (fig. 3 and 4). The signification of these observations is discussed.

Animals↗