Biomedical subjects
R Dawber
Publications and source records attributed to R Dawber.
Soft layered prostheses for arthritic hip joints: a study of materials degradation.
A great deal of interest is being shown in complaint bearing surfaces for artificial joints. These produce very low friction because of the fluid-film lubrication that they exhibit, and therefore should produce lower wear than current prosthetic materials as the two surfaces of the joint are completely separated by a film of synovial fluid. However, one problem with soft elastic materials in vivo is that the elastomers may degrade with time. Specimens of four polyurethanes were kept in Ringer's solution at 37 degrees C for about 4 months to investigate changes in mechanical properties and the mode of lubrication with time of immersion. The materials tested were a polyether-urethane (E57), a polyester-urethane (E58), an aromatic polyether-urethane (P1) and an aliphatic polyether-urethane (A1). Samples of E57 showed a decrease in hardness and elastic modulus of 21% and 28% respectively. This was much better than E58 which showed decreases of 32% and 42% respectively. Better results were achieved with A1 (hardness change 2%) and P1 (decrease in hardness of 14% and modulus 17%). When tested in a hip-function simulator, A1 showed virtually no change in its very low coefficient of friction (0.004), P1 showed an increase of 60%, while E57 and and E58 both showed a doubling in friction over the course of the study. The modes of in vitro degradation were considered and surface effects determined to be most damaging. Currently the best candidate for a compliant material in hip replacement is the aliphatic polyether-urethane which maintains fluid-film lubrication.
Contact dermatitis in reaction to 2% topical minoxidil solution.
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Cryosurgery of hand warts.
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CO2 laser treatment of erythroplasia of Queyrat.
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Trichomycosis axillaris: a different view.
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Twenty-nail dystrophy of childhood: a misnamed syndrome.
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Topical minoxidil for common baldness.
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Chemotherapy for varicella-zoster infections.
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Idoxuridine in herpes zoster: further evaluation of intermittent topical therapy.
In a randomized double-blind controlled trial of the value of intermittent topical idoxuridine in treating herpes zoster in 118 patients idoxuridine 5% in 100% dimethyl sulphoxide (DMSO), applied four-hourly for four days, significantly shortened the vesicular phase, healing time, and duration of pain; idoxuridine 25% applied two-hourly produced no greater benefit. The only side effects were transient tender erythema in three patients and "urticarial" oedema in two patients with dermographia.
Premycotic poikiloderma, mycosis fungoides and cutaneous squamous cell carcinoma. Two cases and a discussion of their relevance.
Two patients with premycotic poikiloderma developed one squamous cell carcinoma each. A review of the literature reveals 28 reported cases of this association, but in 26 of these the patient had been exposed to carcinogens. Our patients had no history of exposure to carcinogenic agents. In both our cases, the squamous carcinomas behaved aggressively. The possible relationship with the poikiloderma is discussed.