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Biomedical subjects

C T Brighton

Publications and source records attributed to C T Brighton.

At least 73 records · Page 4Linked to original sources
PubMed1988

Response of cultured bone cells to a capacitively coupled electric field: inhibition of cAMP response to parathyroid hormone.

Fetal rat calvarial bone cells grown in monolayers were exposed to a capacitively coupled electrical field of 2.62 mV/cm for 2.5-30 min. There was a 59% increase in cAMP concentration after electrical stimulation, compared with a 3615% increase after parathyroid hormone (PTH) administration. PTH administration after electrical stimulation resulted in less cAMP synthesis than following either electrical stimulation alone or PTH administration alone. When PTH administration was delayed for 30 min following cessation of the electrical stimulation, there was an inhibition in the cAMP response. This suggests that one possible mechanism of electrically induced osteogenesis is the desensitization of the bone cell to PTH. Since the effect of PTH is to increase bone resorption, desensitizing or blocking the effects of PTH at the bone cell level would result in a net increase in bone formation.

Animals↗
PubMed1988

Treatment of denervation/disuse osteoporosis in the rat with a capacitively coupled electrical signal: effects on bone formation and bone resorption.

Utilizing a sciatic neurectomy model of disuse osteoporosis, the effects on rates of bone formation and bone resorption were examined when a capacitively coupled electrical signal was applied to the denervated tibia in the rat. It was found that a low-voltage, symmetrical sine wave, 60-kHz, capacitively coupled signal had no significant effect on the amount of bone resorption occurring in denervated right tibiae in rats previously labeled with [3H]tetracycline. This was true whether the signal was applied while osteoporosis was developing (prevention of osteoporosis) or after it had been established (treatment of osteoporosis). If a similar capacitively coupled signal was applied to rats in which osteoporosis was well established, and the rats were labeled with [3H]tetracycline daily during a 12-day treatment period, it was found that there was statistically significant enhancement of the amount of new bone formation (increased [3H]tetracycline incorporation) in the tibiae that received the signal as compared with that of the controls. These results indicate that prevention or amelioration of disuse osteoporosis that occurs with a capacitively coupled electrical signal is due not to a change in the rate of bone resorption, but to an increase in the rate of bone formation.

Animals↗
PubMed1988

Electrical stimulation of onlay bone grafts.

An animal model was developed to determine the ability of capacitively coupled electrical fields to enhance onlay bone graft survival in the craniofacial skeleton. Fifteen male New Zealand white rabbits were divided into control and stimulated groups. Blocks of iliac bone were transplanted as onlay grafts to the mandibular rami. In all animals a capacitor apparatus was attached externally over the right mandibular ramus; however, a 5-V peak-to-peak sinusoidal signal was applied only in the stimulated group. The experimental period was 6 weeks, with a total of 30 days of constant stimulation. Graft resorption in the stimulated animals was decreased a total of 24.8 percent (p less than 0.001). There appeared to be a trend toward decreased graft resorption caused by the apparatus alone, although this was not statistically significant. The electric field alone decreased resorption by 11.5 percent (p less than 0.05). No distinguishing features were demonstrated by fluorescent vital stains or routine histology.

Animals↗
PubMed1988

Treatment of chronic refractory osteomyelitis with adjunctive hyperbaric oxygen.

Twenty-eight consecutive patients with chronic refractory osteomyelitis uncomplicated by persistent segmental bone defect, fracture nonunion, septic arthritis, total joint arthroplasty, or major systemic disease (immune deficiency, malignancy, diabetes mellitus, malnutrition, or renal or hepatic failure) were treated from January, 1980 through December, 1985 to evaluate the potential benefits of hyperbaric oxygen therapy. Patients were classified by a staging system that took into account the bone involved; subchondral, periarticular bone involvement; extent of bone involvement; quality of soft tissue envelope and vascular supply; and general health status of the patient. Using this staging system, patients were assigned to either hyperbaric oxygen therapy or control status after their initial debridement. A regimen of hyperbaric oxygen therapy consisting of 100% oxygen, two atmospheres pressure, two hour duration, one dive per day, six dives per week was used in 14 of the 28 patients. Hyperbaric oxygen had no effect on length of hospitalization, rapidity of wound repair, initial clinical outcome, or recurrence of infection noted to date in this patient population.

Adolescent↗
PubMed1987

Indium-111 leukocyte scintigraphic detection of subclinical osteomyelitis complicating delayed and nonunion long bone fractures: a prospective study.

Twenty patients were studied prospectively with indium-labeled leukocyte imaging to evaluate its effectiveness in differentiating noninfected delayed or nonunion from osteomyelitis complicating these entities. All patients underwent an open surgical procedure within 24 h of the scan. Bone specimens from the nonunion site were obtained for microbiological and histological analysis to confirm the presence or absence of osteomyelitis. In these twenty patients, the sensitivity of the indium scintigraphy was 100%, the specificity 100%, and the overall accuracy 100%. Indium-labeled leukocyte scintigraphy is significantly more accurate than 99mtechnetium and 67gallium imaging had been, when studied earlier, in detecting subclinical osteomyelitis complicating nonunion. Indium-labeled leukocyte scintigraphy should supplant sequential technetium and gallium studies in this patient population when the surgeon must determine whether subclinical osteomyelitis is complicating fracture management of delayed and nonunions.

Adult↗
PubMed1987

Cytosolic calcium concentration in bovine growth plate chondrocytes.

The cytosolic free calcium ion concentration for mammalian cell systems is believed to be maintained within a narrow range compatible with cellular homeostasis. Growth plate chondrocytes have been shown to accumulate large quantities of calcium within their mitochondria, but the cytosolic free calcium concentration has not been determined. This study measures the cytosolic free ionic calcium concentration in growth plate chondrocytes using two variations of the Quin II fluorescence technique. The results indicate that in isolated growth plate chondrocytes, the cytosolic free ionic calcium concentration is similar to other nonmineralizing mammalian cell types (106-137 mM).

Animals↗
PubMed1987

Adjunctive hyperbaric oxygen therapy in the treatment of chronic refractory osteomyelitis.

Twenty-eight consecutive patients with chronic refractory osteomyelitis uncomplicated by persistent fracture nonunion, septic arthritis, total joint arthroplasty, or major systemic disease (immune deficiency, malignancy, malnutrition, renal or hepatic failure) were treated from January 1980 through December 1985 to evaluate the potential benefits of hyperbaric oxygen (HBO) therapy. Patients were classified by a staging system taking into account: the bone involved; subchondral, periarticular bone involvement; extent of bone involvement; quality of soft-tissue envelope and vascular supply; and general health status of the patient. Using this staging system patients were assigned to either hyperbaric oxygen therapy or control status after their initial debridement. Hyperbaric oxygen therapy on a 100% oxygen, 2 atmospheres pressure, 2-hour duration, one dive per day, six dives per week regimen was utilized in 14 of the 28 patients. Hyperbaric oxygen had no effect on length of hospitalization, rapidity of wound repair, initial clinical outcome, or recurrence of infection noted to date.

Adolescent↗
PubMed1987

Antibiotic penetration into rabbit nucleus pulposus.

A rabbit model was used to determine the penetration of four commonly used antibiotics (clindamycin, tobramycin, cephalothin, and oxacillin) into the nucleus pulposus after receiving an 8-hour course of intramuscular antibiotic injections. Clindamycin and tobramycin achieved therapeutic levels in the nucleus pulposus and both were present in greater than 50% of serum levels. Cephalothin was not detected in the nucleus pulposus and penetrated at less than 4% of serum levels at 1 hour after injection. The data were inconclusive regarding oxacillin penetration.

Animals↗
PubMed1987

Morphology and biochemistry of the growth plate.

The structure and function of the growth plate are discussed in detail by Dr. Brighton. Specifically, the blood supply, histology and histochemistry, biochemistry, and ultrastructure of the various zones of cartilagenous portion of the growth plate, as well as the bony and fibrous portions of the growth plate, are described.

Bone Development↗
PubMed1987

Synovial pseudarthrosis: a clinical, roentgenographic-scintigraphic, and pathologic study.

Seventy-six patients with synovial pseudarthrosis were reviewed. This is a distinct pathologic entity which is a different form of nonunion. The humerus, femur, and tibia were the bones most commonly involved. Routine roentgenograms were not beneficial but 99mTc scans were useful for identifying this entity in 93% of cases. Light and electron microscopy revealed normal synovial lining tissue. Motion and infection may lead to the development of this condition. The results of treatment were a 43% success rate in infected cases and 59% for noninfected cases, which is far different from that of regular nonunion.

Diagnosis, Differential↗
PubMed1987

Multiple pathologic fractures of the appendicular skeleton in a patient with Cushing's disease.

A 33-year-old woman with asymptomatic osteoporosis sustained a spontaneous middiaphyseal fracture of the femur as the initial sign of Cushing's disease. Subsequently, she incurred a fracture of the ipsilateral hip and both bones of the forearm. All four fractures failed to unite. There were no symptoms of involvement of the axial skeleton. Although axial osteopenia is the most common skeletal finding in hypercortisolism, fractures exclusively limited to the appendicular skeleton should not preclude detailed diagnostic investigations of hypercortisolism.

Adult↗
PubMed1986

Enhanced survival of rat neonatal cerebral cortical neurons at subatmospheric oxygen tensions in vitro.

In vitro tissue culture experiments are routinely performed at atmospheric oxygen tension (21%), although most cells experience lower oxygen tensions in vivo. The optimal oxygen tension for the survival of neurons and synthesis of neurofilament (NF) was determined using dissociated neonatal rat cerebral cortex and monoclonal antibodies to the 68 kDa and 200 kDa subunits of NF. Maximum production of each subunit determined by Enzyme-Linked Immunosorbant Assay occurred at 9% O2. Neuronal survival determined by immunohistochemistry was also maximal at 9% O2. CNS neurons are highly sensitive to oxygen tension and grow best at levels approximating capillary rather than atmospheric pO2.

Animals↗
PubMed1986

Ultrastructure of electrically induced osteogenesis in the rabbit medullary canal.

The ultrastructural changes in the medullary canal of the adult male New Zealand white rabbit associated with the trauma of the insertion of an inactive cathode were compared to that associated with electrically induced osteogenesis from an active cathode delivering 20 microA constant direct current. In the vicinity of both an inactive and an active cathode, the medullary canal cellular content was replaced first by polymorphic cells and later by osteoblastic new bone formation. The polymorphic cells always appeared in the immediate vicinity of a capillary or other blood vessel. With time, the new bone formation in the medullary canal surrounding the inactive cathode disappeared, while new formation surrounding the active cathode progressively increased in amount. When the new bone formation in the medullary canal surrounding an inactive cathode disappeared, it was replaced by a network of polymorphic cells. When direct current was then applied to such an inactive electrode, the polymorphic cells were again rapidly replaced by bone. The close association of polymorphic cells with osteoblasts suggests that the former may be a precursor cell of the latter.

Animals↗
PubMed1986

Failure of the rabbit tibial growth plate to respond to the long-term application of a capacitively-coupled electrical field.

A continuous 5-V peak-to-peak, 60 kHz capacitively-coupled sine wave signal was applied to the proximal tibial growth plate in fifteen 9-week-old male New Zealand white rabbits for 6 weeks. A pair of flexible stainless steel "injectrodes" was held in place medially and laterally on the surface of the proximal hindlimb in each rabbit by means of tape wrappings. The electrodes were connected to a 9-V battery-operated power unit carried in a dorsal pouch in a body vest worn by each rabbit. Control animals wore the identical apparatus, only the power unit was inactive. Small Tantalum markers were inserted into the anteromedial aspect of the proximal tibial metaphysis 1 cm distal to the proximal tibial growth plate in all of the animals, control and experimental, 2 weeks prior to the onset of electrical stimulation. The distance between the proximal lateral tibial spine and the Tantalum marker, between the Tantalum marker and the apex of the distal tibial intercondylar notch, and between the proximal tibial spine and the distal notch was measured from roentgenograms made at the time of bone marker insertion, at the time of electrode application to the limb, and at the end of the stimulation period. Results indicate that there was no significant difference in tibial lengths between the stimulated and control groups. There was significantly less total body weight gain in both the experimental and control animals than that which occurred in paired normal animals during the same period of time. This failure to thrive may be responsible for the resultant lack of longitudinal growth stimulation of the capacitive coupling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Histochemical localization of calcium in the fracture callus with potassium pyroantimonate. Possible role of chondrocyte mitochondrial calcium in callus calcification.

Potassium pyroantimonate was employed as a histochemical stain for calcium at the ultrastructural level in the cartilaginous fracture callus in the rat rib. In areas of the callus showing no matrix mineralization, the electron-dense precipitate of the antimony-calcium complex was heavily deposited in chondrocyte mitochondria, lipid, and cell membrane. In areas showing early mineralization the mitochondria, lipid, and cell membrane showed a smaller amount of antimony-calcium complex, and in areas of more advanced matrix mineralization the mitochondria, lipid, and cell membrane were completely void of any stain. In the matrix, the initial site of mineralization was associated with matrix vesicles located in areas of early matrix mineralization. These findings suggest the hypothesis that mitochondria play an important role in matrix calcification in cartilaginous fracture callus.

Animals↗
PubMed1986

Nonunion of the humerus. Clinical, roentgenographic, scintigraphic, and response characteristics to treatment with constant direct current stimulation of osteogenesis.

Forty-six trauma patients who had developed non-union of the humerus were evaluated from 1972 through 1981 as part of a large prospective study on nonunion. The average age of the 46 patients was 55 years. Women outnumbered men (29 women and 17 men). Seventy-one percent of the fractures occurred below the midpoint of the humerus. Inadequate immobilization and/or distraction and failure of internal fixation devices to obtain and maintain fracture fragment contiguity and stability was noted. Of the 46 patients referred, 39 were treated with constant direct current, using percutaneously inserted electrodes. Senile and disuse osteoporosis (62%), synovial pseudarthrosis (42%), obesity (20%), and osteomyelitis (5%) in this older patient population made this a difficult treatment problem. Seventeen patients' nonunions healed (46%). Electrical stimulation of nonunion of the humerus is not a panacea. Patient selection is critical.

Adult↗
PubMed1985

Medullary osteogenesis with platinum cathodes.

Studies of electrical stimulation of osteogenesis with stainless steel electrodes have previously established a dose-response relationship between current and bone growth. Examination of the effect of differing geometric current densities resulted in the conclusion that very little electrode surface area was involved in stimulation and led to the design of a multiport "distributive" cathode. A series of experiments were performed to extend these results to wire and multiport platinum electrodes. As before, a current-bone growth dose-response relationship was found. Peak bone growth was greater than for stainless steel. However, peak bone growth occurred at 2.0 microA (versus 20 microA for stainless steel). Correlation studies suggest that small changes in cathodic potential affect bone growth more than similar size changes in current. Finally, the generally benign local host response to platinum suggests that platinum may be a suitable material for chronic indwelling anodes for stimulation of osteogenesis.

Animals↗