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Biomedical subjects

W G Hamilton

Publications and source records attributed to W G Hamilton.

29 records · Page 2Linked to original sources
PubMed1977

Clonal growth of chinese hamster cell lines in protein-free media.

A protein-free synthetic medium, MCDB 301, has been developed for clonal growth of Chinese hamster ovary cell lines. Medium F12 was developed originally for that purpose, but later failed to support good growth without small amounts of serum protein. Growth was restored by the addition of nonphysiological amounts of commercially prepared thyroxine or smaller amounts of the trace element selenium. The thyroxine preparation was shown to contain sufficient selenium to account for all of its growth-promoting activity. MCDB 301 contains increased concentrations of calcium chloride and glutamine, and a smaller amount of cysteine than medium F12. It also has been supplemented with 19 inorganic ions, in addition to selenium and those in medium F12, in order to insure against possible future deficiencies as chemicals are purified further. A Chinese hamster lung line which will not grow in MCDB 301 alone will grow when the medium is supplemented either with methylcellulose or with insulin. The growth-promoting activity is thought to be an impurity shared in common by both substances. The probable "essential" role of impurities in cellular growth in most synthetic media and the problems involved in attempting to develop a truly "defined" medium are discussed.

Animals↗
PubMed1976

Selenium is an essential trace nutrient for growth of WI-38 diploid human fibroblasts.

The trace element selenium is essential for clonal growth of diploid fibroblasts from human fetal lung (WI-38) in media containing small amounts of serum protein. Maximum growth stimulation is obtained when 30 nM neutralized selenious acid is added to a synthetic medium containing 1.5 mg/ml of dialyzed fetal bovine serum protein (equivalent to a 3% serum concentration). Serum appears to be a source of selenium in most culture media, since higher concentrations of serum protein or whole serum mask the selenium requirement of WI-38 cells. Selenium is also required by a Chinese hamster cell line that can be grown in a protein-free synthetic culture medium.

Cell Line↗
PubMedDate not supplied

Personality, stress, and injuries in professional ballet dancers.

Twenty-nine soloist and principal dancers (mean age, 29.08 years) from America's two most celebrated ballet companies were administered questionnaires measuring personality (API), occupational stress (OES), strain (PSQ), and coping mechanisms (PRQ), and injury patterns. The results revealed that male dancers demonstrated significantly more negative personality traits and psychological distress than female dancers or men in the general population. In addition, physical stress and personality traits, characteristic of the "overachiever," distinguished injured dancers. It is suggested that classical ballet's emphasis on the ballerina may be at odds with a masculine identity in male dancers. Furthermore, the qualities that lead to success in this profession may contribute to injuries if carried to an extreme.

Adult↗
PubMedDate not supplied

Cuboid subluxation in ballet dancers.

Cuboid subluxation is a common but poorly recognized condition. Its symptoms include lateral midfoot pain and an inability to "work through the foot." In addition, pressing on the plantar surface of the cuboid in a dorsal direction produces pain. The normal dorsal/plantar joint play is reduced or absent when compared to the uninjured side, and subtle forefoot valgus is present. Frequently, there is a shallow depression on the dorsal surface of the foot and palpable fullness on the plantar aspect of the cuboid. Documentation by radiograph, CT scan, or magnetic resonance imaging is difficult because of the normal variations found in the relationship between the cuboid and its surrounding structures. The diagnosis is primarily subjective, and must be made on the basis of the patient's history and physical findings. Treatment requires recognition of the condition, manual reduction by a therapist or physician familiar with the condition, and follow-up to be certain that the cuboid remains in place. Therapists and orthopaedists involved in the care of dancers should be alert to the possibility of cuboid subluxation and be able to recognize it when it occurs.

Adult↗
PubMedDate not supplied

A profile of the musculoskeletal characteristics of elite professional ballet dancers.

Twenty-eight principal dancers and soloists from America's two most famous ballet companies were examined for anthropometric measurements, including flexibility, muscle strength, and joint range of motion. Both male and female dancers were flexible, but not hypermobile, and did not differ significantly from each other. Marked differences were found between the range of motion of the hip and ankle in the dancers and the norms for the general population. The increased external rotation of the hip in women was accompanied by a loss in internal rotation, resulting in an increased range of motion with an externally rotated orientation. The men, however, lost more internal rotation than they gained in external rotation. These data raise the possibility of a torsional component to the turned-out hip position in elite female professional ballet dancers. In addition, significant anatomic differences separate elite dancers of both sexes from the normal population.

Adult↗
PubMedDate not supplied

Fractures of the distal shaft of the fifth metatarsal. "Dancer's fracture".

We retrospectively reviewed the office records of the senior author--which include two national ballet companies--and identified 35 dancers who sustained distal shaft fractures of the fifth metatarsal. The usual fracture pattern is a spiral, oblique fracture starting distal-lateral and running proximal-medial. Treatment consisted of open reduction and internal fixation for 2 patients, closed reduction and percutaneus fixation for 2 patients, short leg weightbearing cast for 7 patients, and an elastic wrap and treatment of symptoms for 24 patients. Patients with marked displacement of the fracture underwent internal fixation early in the study period; but more recent treatment emphasized nonoperative means, even for displaced fractures. The average time to pain free walking was 6.1 weeks (range, 0 to 16); return to barre exercises, 11.6 weeks (range, 4 to 48); and return to performance, 19 weeks (range, 6 to 52). There was one delayed union (7 months) and one refracture (2 months) that subsequently healed. All patients returned to professional performance without limitation and no patient reported pain with performance at followup. Spiral fractures of the distal shaft of the fifth metatarsal are common injuries and can usually be treated nonoperatively for these high performance athletes without long-term functional sequelae.

Adult↗
PubMedDate not supplied

Sprained ankles in ballet dancers.

Ankle sprains are common in dancers. They result from working in the positions which allow increased risk of sprain on the lateral side of the ankle for many hours a day. One hundred ankle injuries were evaluated. The mechanisms of injury are presented, as well as a classification of these injuries. The recommended treatment and rehabilitation are discussed. Leg muscle strength must be restored before rehabilitation is considered complete.

Ankle Injuries↗