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Biomedical subjects

A Dhem

Publications and source records attributed to A Dhem.

At least 55 records · Page 3Linked to original sources
PubMed1988

Age changes in human bone: a microradiographic and histological study of subperiosteal and periosteal calcifications.

Age changes in subperiosteal areas of human bones are described in 56 subjects of both sexes aged 18-96 years, using microradiographic and histological analysis of thick undecalcified sections from the midshaft of the femur, the tibia, the third metacarpal bone and the third rib. Till the age of 39, most areas of the subperiosteal bone consist of circumferential fundamental lamellae. From the age of 48, certain areas of the subperiosteal bone appear hypercalcified, while in others mineral precipitations occur in the inner layer of the periosteum close to the bone cortex, involving the deep periosteal fibers. These periosteal calcifications should partially account for the increase in transverse diameter of bones throughout adult life.

Adult↗
PubMed1988

Induced acute ischaemia in dog bones: age-related effects.

Acute ischaemia was induced in the lower limb of both growing and adult dogs by injection of the femoral artery with a suspension of carborundum and ground glass in physiological saline. Besides the gangrenous process observed in all the animals, the most striking finding was the quite different reaction between the two groups of dogs. The ischaemic bones of the growing dogs presented a tremendous periosteal woven bone formation and, to a lesser extent, an endosteal one. This new bone apposition was accompanied by compact bone resorption. The osteogenic phenomenon involved in some degree metaphyseal and epiphyseal intertrabecular spaces. This process took place from the 12th day of experiment and was never observed in the adult dogs. It can be interpreted as the result of the transitory periosseous vascular system activity originating from the surrounding soft tissues. Furthermore, the physiological inactivity of the periosteal osteogenic layer in the adult animals is probably responsible for the absence of osteogenic reaction in this experimental group.

Acute Disease↗
PubMed1988

Metopic sutural closure in the human skull.

The present study reveals the presence in the sutural area of secondary cartilage, assuring the passive growth of the bones and undergoing an endochondral ossification, but without playing a direct role in the synostosis. The chondroid tissue is responsible for the growth of each frontal bone towards the other and constitutes the first bridge of union between the two bones. It is the most important finding in this study, which provides a description of the closure of the metopic suture and of the maintenance of an open sutural space by a process of active resorption. This new knowledge will help to understand better the whole process of suture closure and its pathology.

Cartilage↗
PubMed1988

Bone vitality in the cat's irradiated jaw. Histological study.

The vitality of the mandible in cats was studied from two to 15 months after irradiation. Dose of 80 Gy in three days was delivered using three hairpin shape iridium-192 wires surrounding the mandibula. The osseous vitality was assessed from the percentages of lacunae inhabited by osteocytes (IL). The results are compared with those obtained by microradiography. At two months, a small reduction of vitality is already observed, it becomes progressively more important. At one year, vitality is recovered nearly fully in the ventral part of the mandibula, mainly at the level of the alveolar crest. Vitality remains reduced in the dorsal part. Microradiographic lesions appear more slowly; they are apparent at six months.

Animals↗
PubMed1987

Actin and myosinlike structure induced in the growth cartilage by acute ischemia.

Acute ischemia was induced in the lower limb of growing dogs by injecting the femoral artery with a suspension of carborundum and ground glass in physiological saline. This resulted in the loss of the cellular pattern and the cartilaginous matrix in the growth cartilage. The production of myofibrillike material was observed only in the growth cartilage as well as in the intertrabecular spaces of metaphysis in the injected leg.

Actin Cytoskeleton↗
PubMed1987

Electron microscopic study of chondroid tissue in the cat mandible.

This paper deals with electron microscopic appearance of chondroid tissue. Samples from eight cat mandibles were studied without decalcification. The ultrastructural characteristics of the chondroid tissue cells are common with young osteocytes. The interterritorial matrix of chondroid tissue is mineralized, being constituted of large collagen fibrils and calcospherites. The compositions of these parts of the chondroid tissue matrix and of bony matrix are similar but they are two different tissues. The pericellular matrix of the chondroid tissue consists of finely branched filaments, thin collagen fibrils, and an abundant ground substance. It resembles a cartilage matrix and contains type II collagen which is not present in bony matrix.

Animals↗
PubMed1987

Cartilage calcification in the human thoracic column.

A histological and microradiological study of the cartilage calcification processes in the human thoracic column of an old man has been performed. Two different types of cartilage mineralization have been identified. The first corresponds to a calcification of the hyaline cartilage ground substance where chondrocytes are apparently intact. The second is a real mineralization of the chondrocyte lacunae in an uncalcified matrix, which we have called cartilaginous necrosis.

Aged↗
PubMed1987

Considerations about the cloverleaf skull.

The study of four cloverleaf skulls (two fetuses, one infant, and a young adult) concerns two Pfeiffer syndromes, a thanatophoric dysplasia and an isolated case. Clinical and radiologic examinations showed malformations at the level of the calvarium, the base, orbital cavities, and, sometimes, limb abnormalities. Correlations between these findings and the microradiographic analysis of nondemineralized sections elucidate this trilobular appearance of the skull. Premature temporoparietal suture closure terminates at a constricted surface of the lateral sides of the skull during the fetal life. Extension of the synostosis to coronal and frontal sutures and thickening of the occipital bone squama block lengthening of the skull. The consecutive reduction in skull volume is compensated by the maintenance of the permeability during the neonatal period of the sagittal and lambdoid sutures. Microradiographic examination shows that this anomaly may be of vascular origin and associated with abnormal osteoclastic resorption.

Adult↗
PubMed1987

[Distribution of haversian remodeling in the human femur by an osteon count. A study of 6 femurs in cadavers].

To estimate the remodelling of diaphyseal compact bone in the femora of five subjects aged between 63 and 83 years, osteons and osteon fragments were counted. The measurements were made from microradiographs of transverse sections at all levels in the diaphysis. The ventral, dorsal, lateral and medial quadrants were considered separately. The mean osteon count was uniform in all quadrants and at all levels in the proximal two-thirds of the diaphysis, but tended to be less in the distal third. In addition, there were nearly always more osteons, complete and fragmented, per square millimetre in the subperitoneal region than in the neighbourhood of the medullary cavity. In older subjects, there does not seem to be a relationship between the remodelling of femoral compact bone and the specific mechanical stresses in each diaphyseal quadrant.

Aged↗
PubMed1986

[Anatomical variations at the level of the muscles of the arm].

The muscular anatomical variations of the thoracic member are recorded in a series of 180 subjects. Two muscles are supernumerary: a bilateral accessory coraco-brachialis and a unilateral accessory palmaris longus. Two muscles have additional tendons: the extensor carpi radialis brevis and the extensor digitorum.

Aged↗
PubMed1985

Comparison of the calcium content of different tissues present in the human mandible.

Qualitative and semi-quantitative comparisons of calcium content in the developing human mandible were performed by means of microradiographic and histophotometric analysis. Differences in calcium content between enamel, calcified cartilage, chondroid tissue and dentin are significant at the 1% level. Chondroid tissue and woven bone are almost similarly mineralized tissues.

Bone Development↗
PubMed1984

The mandibular body of the human fetus. Histologic analysis of the basilar part.

Histologic and microradiographic analyses of 47 human mandibles from 42 fetuses and 5 neonates have been carried out to study the development of the mandibular body. This not only entails woven bone formation along Meckel's cartilage but also endochondral ossification in the condylar cartilage, the pillars of which are included in the posterior part of the mandibular body. Progressively, woven bone is replaced by lamellar bone, and typical Haversian systems are already present at the fifth month of fetal life. This early occurrence of bone remodelling is related to the fact that the mandible is subjected to intense activity from sucking and swallowing.

Fetus↗
PubMed1984

Effects of retinoic acid on rat bone.

The effects of retinoic acid on rat bones were investigated. Fifteen adult male Sprague-Dawley rats were given various oral doses of retinoic acid (0-20 mg/kg body weight/day, 5 days/wk) and were killed after various treatment periods (1-17 wk). Histological and microradiographic examination of the bones showed the presence of lesions, the development of which was dependent on the dose and the duration of treatment. These lesions were characterized by a dissolution of bone matrix, leaving only fibrils, by osteocytic osteolysis and by an increase in osteoclastic resorption.

Animals↗
PubMed1984

The function of Meckel's and secondary cartilages in the histomorphogenesis of the cat mandibular symphysis.

Cat mandibular symphysis was investigated with histological methods in animals of ages between 3 weeks of intra-uterine life and 56 days post-natal. As in rodents, carnivores and insectivores, Meckel's cartilages fuse in the midline and form a cartilaginous nodule which persists in the symphysis until birth. This nodule, which we have called the symphyseal Meckelian islet, is isolated from Meckel's cartilage, of which only very small calcified islets are left as intramandibular traces after endochondral ossification. Both hemimandibles are bordered by secondary cartilage, which undergoes endochondral ossification, and by chondroid tissue, which is less abundant than in man. At birth, secondary cartilage of both hemimandibles forms a synchondrosis, the lingual part of which undergoes gradual resorption in the 4-week-old cat. The vestibular part is still present at 8 weeks.

Aging↗