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Biomedical subjects

R R Cooper

Publications and source records attributed to R R Cooper.

At least 19 recordsLinked to original sources
PubMed1987

Bone structure and function.

Bone is a complex, living, constantly changing tissue. The architecture and composition of cancellous and cortical bone allow the skeleton to perform its essential mechanical functions. The stiffer cortical bone responds more slowly to changes in loads while cancellous bone has a much larger surface area per unit volume and a greater rate of metabolic activity. Periosteum covers the external surface of bone and consists of two layers: an outer fibrous layer and an inner more cellular and vascular layer. The inner osteogenic layer or cambium layer can form new bone while the outer layer forms part of the insertions of tendons, ligaments and muscles. The cortical bone of diaphyses and metaphyses has a dual blood supply that allows loss of one source of circulation without adversely affecting the viability of the tissue. Many epiphyses, even in adults, depend only on a single source of blood supply, the penetrating epiphyseal vessels. For this reason epiphyseal bone may infarct more easily than metaphyseal or diaphyseal bone. The bone matrix has an organic component, primarily type I collagen, which gives it tensile strength and an inorganic component, primarily hydroxyapatite, which gives it stiffness to compression. Specialized populations of bone cells form, maintain and remodel this matrix. We recognize four types of bone cells based on their locations, morphology and functions: osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts. Osteoblasts develop from undifferentiated cells while osteocytes form from osteoblasts. Osteoclasts have a separate stem cell line, blood-borne monocytes. Bone matrix apparently attracts these monocytes and stimulates their differentiation into osteoclasts. The processes of bone modeling and remodeling require osteoclastic resorption of bone matrix and deposition of a new matrix by osteoblasts. Modeling shapes and reshapes bones during growth and stops at skeletal maturity. Physiologic remodeling does not change bone shape and consists of bone resorption followed by bone deposition in approximately the same location. Since it continues throughout life it appears to be important for maintenance of the skeleton, but its exact function remains obscure. Adaptive remodeling is the response of the bone to altered loads and may alter the strength, density and shape of bone. In recent years understanding of the control of bone cell function has increased significantly. The study of electrical effects on bone formation has lead to new treatments of nonunions and delayed unions. Physicians have applied understanding of matrix-induced bone formation to reconstruction of skeletal defects.(ABSTRACT TRUNCATED AT 400 WORDS)

Bone Development↗
PubMed1985

Talectomy. A long-term follow-up evaluation.

Of 26 talectomies with an average follow-up period of 20 years, 24 (92%) were judged to have satisfactory results. The average age at surgery was 10.25 years; however, there is no ideal age for performing talectomies. The results seem to be equally good regardless of the preoperative deformity. The procedure did produce stable, painless plantigrade feet. Talectomy has a place in orthopedic surgery today. However, this drastic procedure is indicated only in those feet where the deformity is rigid and severe, where a plantigrade foot is required in patients who are younger than the age usually recommended for triple arthrodesis, and where experience has shown that other, less radical approaches would be unsatisfactory.

Child↗
PubMed1979

Annular constricting bands.

We reviewed forty-five patients with congenital constriction bands with an average follow-up of 15.8 years. The family history and associated anomalies were recorded and particular attention was paid to temperature gradients and neurocirculatory deficits with respect to band location. No family history of band constrictions was elicited. Most of our patients were products of first pregnancies and of young mothers. Deformity of the nails was a constant finding in patients with distally located bands. All patients demonstrated at least one other anomaly, most commonly a malformation of the hand. Neural deficits were noted in 23 per cent of the patients, while circulatory findings appeared in 16 per cent. A significant temperature gradient averaging 2.38 degrees Celsius was noted in twenty patients in whom the bands were located proximally. All patients with neural deficits demonstrated a significant temperature gradient. Staged z-plasty was the procedure of choice in surgical release of constriction bands.

Abnormalities, Multiple↗
PubMed1978

Sheathing of collagen fibrils in human intervertebral discs.

In 25 human intervertebral discs studied by electron microscopy, sheathing collagen-like fibrils by electron-dense cylinders was observed. The sheaths consisted of layers of dense granules 3 to 12 times the diameter of the enclosed collagen-like fibrils, and they appeared to be more frequent in older discs.

Adult↗
PubMed1977

An ultrastructure investigation of intrafusal muscle fibers in myotonic dystrophy.

Ultrastructure features of muscle spindles from two patients with myotonic dystrophy are described. Intrafusal muscle fibers exhibit extensive splitting with nuclear bag fibers affected more so than nuclear chain fibers. No sensory endings are present on nuclear chain fibers nor on one nuclear bag fiber throughout the equatorial and myotube regions. Small motor end plates are evident on various segments of split intrafusal fibers in the polar region and some of these extend into the myotube region. Satellite cells are numerous on both nuclear bag and nuclear chain fibers. These frequently occupy the cleft space between segments of split intrafusal fibers. The myotonic dystrophy muscle spindle ultrastructure features seem to closely resemble the appearance of developing mammalian muscle spindles as illustrated with opossum fetal tissue.

Adult↗
PubMed1977

The ultrastructure of the growth plate in slipped capital femoral epiphysis.

Core biopsy specimens of the proximal femoral growth plate from three patients with slipped capital femoral epiphysis were studied by light and electron microscopy. In the resting zone, the cartilage matrix was composed of large, densely packed collagen fibrils. The cartilage matrix in the zones of chondrocyte hypertrophy where the slippage occurred contained only scattered fine collagen fibrils in a homogeneous ground substance. The change in composition of cartilage matrix in the distal region of the epiphyseal plate may predispose that region to slippage.

Adolescent↗
PubMed1976

Elastic fibers in human intervertebral discs.

Although previous studies failed to demonstrate elastic fibers in intervertebral discs, electron microscopy of twenty human intervertebral discs obtained at autopsy and operation revealed characteristic elastic fibers in both the annulus fibrosus and the nucleus pulposus. Their contribution to the mechanical properties of the intervertebral disc remains to be determined.

Adolescent↗