Biomedical subjects

S A Feik

Publications and source records attributed to S A Feik.

22 records · Page 2Linked to original sources

PubMed1982

Joint changes in transplanted caudal vertebrae.

Both straight and bent segments of tails from 4-d-old and weaning Sprague-Dawley rats were used to study the changes which occur in symphyseal joints on transplantation to non-functional sites. In the joints from the younger donors ankylosis occurred almost invariably in the proximal end of the tail, while distally it was rarely seen unless the tail was curved, when ankylosis was visible on the inner side of the bend. The joints from the older donors showed a more varied response on transplantation. Some appeared unaltered, in others where growth continued, calcific changes were seen. In bent segments, unlike in younger ones, ankylosis occurred preferentially on the outer side of the bend. Histological examination revealed that ankylosis of the joint occurred through a process of chondroid metaplasia of the intervertebral connective tissue with subsequent replacement by bone. The metaplastic joint changes were primarily the results of pressure producing compression of the annulus fibrosus in tissues with a reduced vitality due to transplantation and lack of function.

Aging↗

PubMed1982

Remodelling of bone and bones. Effects of altered mechanical stress on anlages.

Tails from 4-day-old Sprague-Dawley rats were bent in situ or skinned bent tail segments were transplanted s.c. into 50 g hosts. Tissue changes were studied for up to 24 weeks by radiographic and histological techniques. The early changes in situ resulted largely from limited translation of bones within their encasing tissues with resorption on the leading (pressure) side inducing thinning, and on the trailing (tension) side thickening of bone. The changes in transplanted anlages occurred in 3 stages: initially, bending of the anlages, with tension between the stretched periosteum and the outer bone surface inducing formation, and compression of cartilage and bone on the inner aspect leading to resorption; then resumption of longitudinal growth and expansion of the bent loop leading to translation of bones within the encasing soft tissues with resorption and thinning of bone on the leading pressure side and formation, with thickening of the inner shaft, on the trailing tension side; and finally with cessation of growth and translation, a reversal to the previous phase. The results support the hypothesis that 2 processes are involved: first, internal stress, and second, translation of bones with, in all instances, pressure inducing resorption and tension inducing formation of bone.

Animals↗

PubMed1979

Low-calcium/high phosphorus rickets in rats. I. Mast cell changes.

Weanling rats were given a low Ca (0.003%)/high P (0.64%) diet with and without vitamin D for periods up to 5 weeks. This was associated with hypocalcaemia, rachitic bone changes and increased bone resorption. These changes preceded the accumulation of large numbers of mast cells in long bone metaphyses. Mast cells did not increase in the epiphyses of long bones or in caudal vertebrae, tooth pulp, skin and other organs. A light and electron microscopic study showed that most mast cells had raised secretory activity, as evidenced by variability in the structure of granules and loss of granule contents, particularly in animals with the lowest serum calcium levels. It was not possible to relate the position of a mast cell to an area of active bone formation or resorption. The increase in mast cells might be related more to the maintenance of connective tissue integrity in areas of rapid bone remodelling.

Animals↗

PubMed1979

Low-calcium/high-phosphorus rickets in rats. II. Osteoclast changes.

Weanling rats were given a low Ca (0.003%)/high P (0.64%) diet with and without vitamin D for periods up to 6 weeks. An ultrastructural examination of selected areas of the proximal tibial metaphysis was carried out to study osteoclasts and their relation to calcified and uncalcified bone tissue. Osteoclasts were seen with ruffled borders adjacent to unmineralized osteoid or with their processes penetrating small patches of calcified osteoid tissue. In both cases the calcified bone margin had a 'frayed edge', suggesting that osteoclasts are capable of chemical demineralization, as well as phagocytic action. In a few cases, osteoblasts were seen adjoining osteoid seams with underlying calcified bone exhibiting frayed edges indicative of demineralization. Osteoclastic intranuclear inclusion bodies similar to those found in experimental lead poisoning were observed. It was considered that the presence of a frayed, calcified bone margin at a considerable distance from the osteoclast supports the proposition that the initial action of this cell is to demineralize calcified bone.

Animals↗