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Biomedical subjects

C T Brighton

Publications and source records attributed to C T Brighton.

At least 127 records · Page 7Linked to original sources
PubMed1981

A multicenter study of the treatment of non-union with constant direct current.

A clinical study was initiated at the University of Pennsylvania in 1970 to evaluate the use of constant direct current in treating acquired non-union. In 1977 the study was expanded to include twelve participating investigators throughout the United States. The results indicate that, given proper electrical parameters and proper cast immobilization, a rate of bone union comparable to that seen with bone-graft surgery was achieved. Experience dictated that four cathodes, each delivering twenty microamperes of constant direct current for twelve weeks, were required to heal a non-union of a long bone. Of 178 non-union in 175 patients treated with adequate electricity in the University of Pennsylvania series, 149 (83.7 per cent) achieved solid bone union. Patients with a history of osteomyelitis had a healing rate of 74.4 per cent. The presence of previously inserted metallic fixation devices did not affect the end-result healing rate. Of eighty non-unions in seventy-nine patients treated with electricity in the participating investigators' series, fifty-eight (72.5 per cent) achieved solid bone union. Review of the non-unions treated unsuccessfully with constant direct current suggested that inadequate electricity, the presence of synovial pseudarthrosis or infection, and dislodgment of the electrodes are causes for failure with the procedure. Complications of the electrical treatment were minor and there was no deep infection resulting from this procedure in patients without previous osteomyelitis. We concluded that the practicing orthopaedic surgeon utilizing constant direct current to treat non-union should, by adhering to proper fracture management and by following the biophysical principles described herein, be able to achieve a rate of union comparable to that of bone-graft surgery, with a lower associated risk.

Adolescent↗
PubMed1979

Articular cartilage preservation and storage. I. Application of tissue culture techniques to the storage of viable articular cartilage.

Articular cartilage slice explants were stored under various conditions, including freezing-thawing at various rates by using dimethyl sulfoxide (DMSO) as a cryoprotective agent, incubating in standard tissue culture medium (MEM Eagle:NCTC 135:15% fetal calf serum) in 5% CO2 and air at 4 degrees, 21 degrees, and 37 degrees C, and incubating in standard tissue culture medium containing 200 micrograms/ml alpha-tocopherol (vitamin E) at 37 degrees C after first ascertaining a dose-response curve of vitamin E. Results indicated that articular cartilage slice explants did not survive freezing or storage at 4 degrees and 21 degrees C as measured by 35S uptake. When stored at 37 degrees C in standard tissue culture in 5% CO2 and air, the slice explants remained viable for up to 60 days. The addition of alpha-tocopherol to the medium resulted in significantly less release of previously incorporated 35Sin stored cartilage slices and significantly less reduction of the amount of hexosamine present in the stored explants. alpha-Tocopherol in the medium also preserved safranin O staining. Thus, the application of tissue culture techniques to the storage of articular cartilage made it possible to preserve cartilage slice explants in a viable, biochemically "normal" state.

Animals↗
PubMed1979

Articular cartilage preservation and storage. II. Mechanical indentation testing of viable, stored articular cartilage.

Mature rabbit articular cartilage in the form of distal femoral condyles, composite osteoarticular structures, were incubated in the presence of alpha-tocopherol (200 micrograms/ml) over a period of time. Indentation testing and 35S uptake indicate preservation of sustained load carrying capacity and viability, respectively, in the presence of alpha-tocopherol for up to 30 days in organ culture. Condylar cartilage stored in the absence of alpha-tocopherol as well as frozen cartilage demonstrated progressive inability to resist sustained loading over time. Nonoptimal synthetic function apparently occurred in these latter two groups when compared to alpha-tocopherol stored material.

Animals↗
PubMed1978

Radiologic evaluation of the treatment of nonunion of fractures by electrical stimulation.

A procedure is described in which nonunion of fractures is treated by implantation of electrodes with direct electric current at the site of fracture. Of 107 patients treated with electrode stimulation, 71 (66%) healed. If one eliminates 9 cases of congenital pseudoarthrosis and 11 patients treated with only 10 microamperes of current, 70 of 87 patients (8095%) healed. Severe osteoporosis and sclerosis were common radiologic findings, but had no value in predicting which patients would respond to therapy.

Electric Stimulation Therapy↗
PubMed1978

The role of mitochondria in growth plate calcification as demonstrated in a rachitic model.

In a phosphate-vitamin D-deficiency rachitic model in rats, potassium pyroantimonate was employed as a histochemical stain for calcium at the ultrastructural level in the costochondral growth plates. In the control plates, there was a shift of calcium from an intracellular, mainly mitochondrial location in the top part of the zone of hypertrophic cells to an extracellular, mainly matrix-vesicle location in the bottom part of the zone of hypertrophic cells. In the rachitic plates, mitochondria and cell membranes throughout the bottom of the hypertrophic zone remained heavily loaded with calcium. After treatment with phosphate was started, the mitochondria and cell membranes at the bottom of the hypertrophic zone rapidly lost calcium and matrix calcification began. Thus, in the normal growth plate, matrix calcification begins at the level in the plate where mitochondria lose calcium; in rickets, the matrix does not calcify and mitochondria do not lose calcium; and in healing rickets, calcification begins in the matrix at the bottom of the hypertrophic zone as the mitochondria at that level lose calcium. These findings support the hypothesis that mitochondria play an important role in matrix calcification.

Animals↗
PubMed1977

Treatment of nonunion with constant direct current.

Laboratory experiments show the following relationships between electricity and bone: (1) stressed bone exhibits electronegativity in areas of compression, (2) living, nonstressed bone exhibits electronegativity in areas of bone growth and healing, and (3) the application of low magnitude direct current to bone induces osteogenesis at the negative electrode or cathode. Based on the above principles, a clinical study was performed in which 10-20 microamperes of constant direct current was used in treating nonunion in 57 patients. The results suggest that specific electrical parameters are required for successful osteogenic stimulation in patients. When these electrical parameters are met, a successful healing rate of 70 per cent can be achieved in treating nonunion with direct current. As experience is gained with this new technique in the treatment of nonunion, the results should improve even further. Basic studies exploring the mechanism(s) whereby electricity induces osteogenesis are opening new vistas into our understanding of bone growth and repair. The extension of these basic studies has far-reaching clinical implications.

Adult↗
PubMed1977

Anaerobic and aerobic metabolism in articular cartilage.

Articular cartilage explants were incubated at various oxygen tensions and the results of 35SO4 and 3H-thymidine incorporation indicate that proteoglycan and DNA synthesis is depressed at low oxygen tensions. The studies of oxygen consumption and glucose/lactate metabolism in the cartilage suggest a shift in energy pathways as the oxygen environment is altered. In low O2 tensions chondrocytes follow anaerobic glycolysis while at physiologic oxygen tensions chondrocytes follow a combination of both aerobic and glycolytic metabolism. The data suggest that hypoxia, frequently found in inflammatory arthritides, would have deleterious effects on chondrocyte metabolism and would significantly impair any reparative potential of the injured chondrocytes.

Animals↗
PubMed1977

Joint resurfacing in the rabbit using an autologous osteochondral graft.

In rabbits, joint resurfacing with autologous osteoarticular condylar grafts composed of the articular cartilage and subchondral bone (two to eight millimeters thick) from the lateral femoral condyles was investigated. By means of morphological, histochemical, autoradiographic, and biochemical studies, the grafts were compared with sham and normal controls. When adequately fixed, the grafts remained viable and functionally and structurally intact during the twelve months of the experiment. The subchondral bone underwent rapid replacement in less than six weeks without loss of its supportive function. Resurfacing of a joint using an osteochondral graft is feasible in rabbits.

Animals↗
PubMed1976

Fracture healing in the presence of chronic hypoxia.

Recent studies have demonstrated that fracture healing normally takes place under hypoxic conditions. The present study evaluated the effect of a state of chronic systemic hypoxia on fracture healing in dogs. A significant delay in fracture healing was demonstrated in the hypoxic animals roentgenographically, histologically, and by strength-testing criteria. A further reduction in the available oxygen supply below that present during normal repair had an adverse effect on fracture healing.

Animals↗
PubMed1976

Histochemical localization of calcium in growth plate mitochondria and matrix vesicles.

K-pyroantimonate is an anion that forms an electron-dense precipitate with cellular cations that is readily visualized at the ultrastructural level. The staining process is made relatively specific for calcium by comparing pyroantimonate treated sections to sections pretreated with ethylene glycol-bis-N,N'-tetraacetic acid, a chelating agent that removes calcium but not other cellular cations. By these means, it is shown that the antimonate-calcium complex is located predominantly in mitochondria and cell membranes throughout most of the growth plate. In the degenerating zone, however, there is a gradual loss of stain complex from the mitochondria and cell membranes and a concomitant accumulation of the stain complex by matrix vesicles. The latter are the initial site of mineralization in the growth plate as detected by these means. Thus, this study suggests that intracellular calcium plays a significant role in matrix calcification.

Animals↗
PubMed1976

Shear strength of the human femoral capital epiphyseal plate.

After the determination of the shear strength and modes of failure of the capital femoral epiphyseal plates in twenty-five pairs of hips obtained post mortem from children five days to fifteen years and ten months old, with the plate intact on one side and with the perichondrial fibrocartilaginous complex removed on the other, the gross and microscopic morphology was studied. The shear strength of the human epiphyseal plate varied with age and was greatly dependent on the surrounding perichondrial complex in infancy and early childhood, but less so in adolescence. When this complex was excised, the strength of the epiphyseal plate was diminished, especially in specimens from younger children. The forces necessary to cause slipping were found to be within the physiological range of the force that would be generated in overweight children, suggesting that purely mechanical factors may play a major role in the etiology of slipped capital femoral epiphysis.

Adolescent↗
PubMed1976

In vitro epiphyseal-plate growth in various constant electrical fields.

An in vitro epiphyseal-plate model was subjected to various electrical fields. At a voltage gradient of 1500 volts per centimeter, a consistent, highly significant acceleration of growth of the epiphyseal plate occurred as measured from photomacrographs and as indicated by incorporation of 45Ca, 35S, and 3H-thymidine. The growth acceleration was due to voltage gradients and not to current flow. Although the mechanism of action of the electrical field is not known, it is obvious that the voltage gradient, either directly or indirectly, incites a physiological response of the growth-plate chondrocyte.

Animals↗
PubMed1975

Cathodic oxygen consumption and electrically induced osteogenesis.

Small amounts of electric current stimulate bone formation in the region of a cathode. The purpose of this experiment is to compare changes in oxygen and hydroxyl ion concentration that occur at the cathode at current levels known to be capable of inducing osteogenesis (10-20 muamps) with those changes that occur at current levels known to be toxic to bone (100 muamps). An oxygen consumption chamber containing an oxygen electrode is fitted with two stainless steel electrodes which are connected to a constant current source. At the cathode, with a current of 100 muamps, oxygen is consumed at nearly stoichiometric rates. At higher current (100 muamps) levels, cathodic oxygen consumption gives way to hydrogen evolution. Cathodic hydroxyl ion production is directly proportional to current. It is concluded from these in vitro experiments that at 10-20 muamps the oxygen tension in the vicinity of the cathode is lowered and the pH is moderately increased. At 100 muamps the oxygen tension is not lowered, but the pH is increased dramatically. If these same changes occur in the vicinity of a cathode in vivo, then lowering the local tissue oxygen tension and raising the local pH may be mechanisms operative in electrically induced bone formation.

Chemical Phenomena↗
PubMed1975

Direct-current stimulation of non-union and congenital pseudarthrosis. Exploration of its clinical application.

Based on the response of bone to electrical current in previous studies, an exploratory clinical study of the effect of electrical current on non-union and congenital pseudarthrosis was performed. Constant direct current of ten to twenty microamperes was applied to twenty-four non-unions and five congenital pseudarthroses. Complete union occurred in fifteen non-unions and in one congenital pseudarthrosis. A single cathode delivering ten microamperes seemed sufficient to heal non-union in small bones, but multiple cathodes each delivering twenty microamperes appeared to be required to heal non-union in the tibia and femur. As the technique was refined, the percentage of successes increased. While these preliminary results appear promising, further laboratory and clinical experiments are required to define the true role of electrical stimulation in clinical practice.

Adolescent↗