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Biomedical subjects

A G Bevin

Publications and source records attributed to A G Bevin.

At least 19 recordsLinked to original sources
PubMed1988

Tendon synovial cells secrete fibronectin in vivo and in vitro.

The chemistry and cell biology of the tendon have been largely overlooked due to the emphasis on collagen, the principle structural component of the tendon. The tendon must not only transmit the force of muscle contraction to bone to effect movement, but it must also glide simultaneously over extratendonous tissues. Fibronectin is classified as a cell attachment molecule that induces cell spreading and adhesion to substratum. The external surface of intact avian flexor tendon stained positively with antibody to cellular fibronectin. However, if the surface synovial cells were first removed with collagenase, no positive reaction with antifibronectin antibody was detected. Analysis of immunologically stained frozen sections of tendon also revealed fibronectin at the tendon synovium, but little was associated with cells internal in tendon. The staining pattern with isolated, cultured synovial cells and fibroblasts from the tendon interior substantiated the histological observations. Analysis of polyacrylamide gel profiles of 35S-methionine-labeled proteins synthesized by synovial cells and internal fibroblasts indicated that fibronectin was synthesized principally by synovial cells. Fibronectin at the tendon surface may play a role in cell attachment to prevent cell removal by the friction of gliding. Alternatively, fibronectin, with its binding sites for hyaluronic acid and collagen, may act as a complex for boundary lubrication.

Animals↗
PubMed1988

Cell populations of tendon: a simplified method for isolation of synovial cells and internal fibroblasts: confirmation of origin and biologic properties.

Tendons transmit the force of muscle contraction to bone to effect limb movement. Special structural and biological properties of tendon have developed to facilitate force transmission. The tendon has a complex organization of cells surrounding the collagen bundles inside tendon as well as at the tendon surface. Internal cells may act to maintain the bulk of the collagen in tendon. External cells in the epitenon may provide lubrication for tendon gliding. To develop better understanding of these processes and the roles the cell populations play, we isolated cells from the surface and interior of tendon and studied them in vitro. Flexor tendons from 8-week-old white Leghorn chickens were separated into two distinct cell populations: the outer synovial cells and the fibroblasts more internal in tendon. These cell populations were discernible by their locations in the intact tendon, determined by sequential enzymatic and physical release from their substrata. Initially, some cells eluted in Hanks' salt solution (HSS) (population 1); then synovial cells were released after a 2-min treatment with 0.5% collagenase (population 2). Next, a population of synovial cells was released in high yield by treatment with 0.25% trypsin (step III, population 3). Step III, population 3 cells were used as synovial cells (SCs). Next, a population of SCs and fibroblasts were released by scraping with a rubber policeman (population 4). Subsequently, fibroblasts were released after incubation with 0.5% collagenase (population 5). A more direct procedure (procedure 2) to isolate the synovial and internal tendon cells involved treatment in 0.5% collagenase followed by sedimentation at 900 g. Cells that sedimented were largely fibroblasts, whereas the cells that remained at the top of the tube were largely SCs. Cells designated as SCs, isolated by procedure 2, most likely contained surface cells from epitenon and internal interfascicular cells from endotenon and paratenon. Surface tendon cells separated by sequential enzymatic and physical release from their substrata (by procedure 1) had all the following characteristics: distinct subpopulations of cells based on morphology; presence of cytoplasmic, lipid-containing vesicles; decreased sensitivity to trypsin; and reduced generation time as compared with that of internal fibroblasts. Conversely, the internal fibroblasts (IFs) appeared to represent a more uniform population based on morphological characteristics.

Animals↗
PubMed1984

Closure of large spina bifida cystica defects with bilateral bipedicled musculocutaneous flaps.

A report of 19 cases of large spina bifida cystica defects closed with bilateral bipedicled latissimus dorsi musculocutaneous flaps is presented. This procedure offers a distinct advantage over other procedures used currently: (1) any large defect in the thoracic, lumbar, and sacral area can be repaired without tension; (2) the flaps have good blood supply; (3) they require no delay, and operative time and blood loss are minimized; and (4) excellent results have been obtained using this safe, predictable technique with a minimum of complications.

Child↗
PubMed1981

Effects of trauma and partial devascularization on protein synthesis in the avian flexor profundus tendon.

Destruction of the blood supply to tendons adversely affects healing of repaired flexor tendons. In cut and sutured avian flexor profundus tendons, protein synthesis was maximal on Day 10 post-trauma with a broad peak that spanned at least 12 days. Partial devascularization of cut-sutured tendons reduced protein synthesis to 43% of the value for nondevascularized-cut-sutured tendons on Day 10. Both collagen and noncollagen protein synthesis in cut-sutured tendons followed a bimodal pattern with peaks on postoperative Days 10 and 18. Collagen and noncollagen protein synthesis in partially devascularized tendons was decreased. Relative collagen synthesis, that is, the amount of collagen produced compared with the amount of all other proteins produced at the same time, was increased (Days 10 to 15) in the tendons that were cut-sutured and partially devascularized. The latter observations indicate that: 1) cutting a tendon results in increased protein synthesis; 2) partial devascularization of the cut tendon results in a lesser increase in protein synthesis; and 3) although overall protein synthesis, and collagen synthesis in particular, are reduced in partially devascularized, healing tendons, the relative amount of collagen produced is increased, emphasizing the importance of collagen to the healing tendon during the time of maximum synthesis.

Animals↗
PubMed1980

Burn wound sepsis: effect of delayed treatment with topical chemotherapy on survival.

Using a standardized laboratory rat model of burn wound sepsis, a regimen of once a day application of Silvadene has been found to be more effective treatment than Sulfamylon or cerium-Silvadene. Delaying treatment following infection resulted in decreased survival. Possible reasons for difference in mortality are once-daily application, or perhaps a change in sensitivity between drugs and the infective organism (Ps. aeruginosa) over time.

Administration, Topical↗
PubMed1979

A clinical and laboratory evaluation of a polyurethane foam: a new donor site dressing.

A polyurethane foam (Lyofoam) has been reported to accelerate epithelization of a wound. The purpose of this study was to evaluate its efficacy as a donor-site dressing for thermally injured patients. Thus, partial-thickness injuries were made in ten pigs and covered with Lyofoam, Xeroform, Telfa, Scarlet Red, and fine-mesh gauze. Gross and histologic examinations failed to show accelerated healing under the Lyofoam dressing but did show that Scarlet Red covered donor sites healed the fastest. On clinical evaluation, nine patients only showed that Lyofoam separated earlier from the underlying wound but there was no evidence to suggest that the wound was more mature than that covered with fine-mesh gauze.

Animals↗
PubMed1978

Posterior pillar webbing and palatopharyngeus displacement: possible causes of congenital palatal incompetence.

Three cases of congenital palatal incompetence in the absence of the usual stigmata associated with hypernasality are presented. In two instances, mucosal webbing of the posterior pillars was noted and in one case the palatopharyngeus muscle was displaced. Hypernasal voice quality was apparent in each patient. A z-plasty on both sides of the posterior pillars is suggested as the treatment of choice when no other morphologic abnormalities are present.

Child↗
PubMed1976

Early tendon transfer for radial nerve transection.

A retrospective comparison of twelve patients with radial nerve transection treated by nerce repair, and thirteen similar patients treated by tendon transfer only, showed an average time to recovery of 7.5 months after nerve repair, and eight weeks after transfer. In view of this, a policy of early tendon transfer instead of radial nerve suture is advised. Results are reported in nine patients who had tendon transfers at an average of thirteen days after nerve injury.

Adult↗
PubMed1976

Augmentation mammaplasty by the transaxillary approach.

Augmentation mammaplasty by the transaxillary approach seems to be a safe and anatomically sound procedure which produces consistent results with a low complication rate. Our experiences with this procedure and our modifications in the technique are described. Two instruments which were designed to facilitate the procedure are reported. An anatomical justification for the transaxillary method is made.

Axilla↗