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Biomedical subjects

B L Diffey

Publications and source records attributed to B L Diffey.

At least 127 records · Page 7Linked to original sources
PubMed1987

Analysis of the risk of skin cancer from sunlight and solaria in subjects living in northern Europe.

The risk of non-melanoma skin cancer in northern Europeans who indulge in sunbathing or use a UVA solarium was estimated using a mathematical model of skin cancer incidence that makes allowance for childhood, occupational and recreational sun exposure. This model demonstrates that the cumulative incidence of skin cancer in indoor workers is about 2-3% by the age of 70, yet this risk can increase 5-fold if they indulge in a two-week sunbathing vacation each summer. The use of a UVA solarium is also shown to increase the risk of skin cancer. Because risk increases with the approximate square of annual solarium exposure, it is not possible to define a 'safe' level of exposure. Instead, it is shown that weekly use of a UVA solarium from age 20 until middle age (40-50) gives a relative cumulative incidence of 1.3 compared with non-users of sun beds and sun canopies. The risk begins to increase rapidly for more frequent use, particularly when solaria are used in combination with sunbathing.

Adolescent↗
PubMed1986

Status of ultraviolet A dosimetry in methoxsalen plus ultraviolet A therapy.

The carcinogenic risk of methoxsalen plus ultraviolet A treatment (PUVA) is almost certainly related to the cumulative UVA exposure dose. A reliable estimate of UVA dose is a major component, therefore, in determining the long-term safety of this treatment modality. Thirty-one UVA meters from twenty-nine different PUVA treatment centers were compared with a calibrated UVA meter. The results inferred that 95% of UVA meters used in PUVA centers are reading between 57% and 159% of the true UVA irradiance, a factor of 2.8 in relative sensitivity. This wide variation in accuracy between the UVA meters gives cause for concern. These variations were attributed to differences in calibration procedure, optical properties of the sensors, and, most importantly, poor quality control by the manufacturers. The situation that appears to have existed since the introduction of PUVA therapy can be improved only if dermatologists agree that the present inaccurate and uncertain approach to UVA measurements is unsatisfactory. Manufacturers of UVA meters should be encouraged to provide instruments as reliable as the dosimeters used in radiotherapy, in which the prescribed dose is probably within 5% of the true value. Ideally, a standard type of UVA meter with appropriate physical properties and an agreed calibration procedure should be used by all centers engaged in PUVA treatment.

Humans↗
PubMed1986

The erythemal response to ultraviolet radiation in subjects with polymorphic light eruption.

A reflectance instrument was used to measure objectively the erythemal response to UV-B and UV-C radiation in subjects with polymorphic light eruption. The characteristics of the dose-response curves obtained for each quality of ultraviolet radiation were significantly different, but were essentially indistinguishable from the comparable dose-response curves measured previously in normal subjects. It is concluded that in this photodermatosis the chromophore(s) and mediator(s) of delayed (24 h) ultraviolet-induced erythema are identical to those in normal skin.

Adult↗
PubMed1986

Occupational exposure to ultraviolet radiation in dermatology departments.

The ultraviolet radiation (UVR) doses received by staff who are occupationally exposed to artificial sources of UVR found in dermatology departments have been measured using personal UV monitors. The results show that staff may receive actinic (UVB and UVC) doses which are in excess of recommended maximum permissible limits for occupational exposure, but that the UVA doses are well within these limits.

Dermatology↗
PubMed1986

Use of UV-A sunbeds for cosmetic tanning.

A survey has been carried out of people using UV-A sunbeds at commercial premises in the U.K. The degree of tan achieved was found to be closely related to the subject's ability to tan in sunlight, and subjects who burnt easily in sunlight were most at risk of developing erythema after using a sunbed. Side-effects, particularly itching, were common. The prevalence of itching, nausea and skin rashes were higher in women taking oral contraceptives than in women on no medication. Although long-term quantitative estimates of the risks of UV-A sunbed use (such as skin ageing and skin cancer) are unknown, it is recommended that individuals who do not tan or tan poorly should be discouraged from using sunbeds.

Adolescent↗
PubMed1986

A quantitative study of the effect of topical indomethacin on cutaneous erythema induced by UVB and UVC radiation.

The effect of indomethacin gel on UVB and UVC erythema was assessed objectively using a reflectance instrument. When indomethacin was applied immediately after irradiation, UVR (ultraviolet radiation) dose-dependent suppression of erythema was demonstrated for both wavelengths until 36 h after irradiation when both indomethacin and control gel base-treated sites were equally erythematous. Suppression of erythema also occurred when application of indomethacin was delayed until 24 h after irradiation, showing that for both wavelengths prostaglandin synthesis remains increased throughout this period. The degree of suppression at any time, however, was no greater than that achieved by a single application immediately after irradiation, indicating that the eventual equal erythema of indomethacin and gel base-treated sites was not due to tachyphylaxis or inadequate dosage. Construction of dose-response curves for the indomethacin-responsive and indomethacin-unresponsive components of erythema shows that in human skin the difference in erythemal response to UVB and UVC radiation is not due to the formation of different mediators at these wavelengths.

Administration, Topical↗
PubMed1986

A new technique for xenon-133 ventilation imaging in the diagnosis of pulmonary embolism.

A new approach to ventilation imaging of the lung using 133Xe in patients with suspected pulmonary embolism is described. Three inhalation images are obtained in the postero-anterior, right posterior oblique and left posterior oblique projections, respectively, and each image contains 140-180 kcounts. The technique is quick and simple and needs neither an oxygen supply nor a spirometer. It combines the multiple views characteristic of krypton imaging with the ease of availability of xenon.

Humans↗
PubMed1986

The spectral emissions from ultraviolet radiation lamps used in dermatology.

The spectral power distributions from a wide variety of ultraviolet radiation lamps used for dermatological purposes have been measured using a high-quality spectroradiometer. The data presented here provide a comprehensive compilation of this fundamental (but often hard to come by) characteristic of ultraviolet lamps.

Dermatology↗
PubMed1985

The erythemal response of human skin to ultraviolet radiation.

A reflectance instrument was used to measure objectively the erythemal response of human skin to ultraviolet radiation. Dose-response curves have been constructed for four radiation wavelengths. In each case, the measured increase in erythema was found to be linearly related to the logarithm of the dose of ultraviolet radiation. Significantly different slopes of response were obtained for radiation of 254 and 280 nm compared with 300 and 313 nm radiation. The relevance of these findings is discussed with relation to the mechanism of erythema production and the erythema action spectrum.

Adult↗
PubMed1985

An evaluation of sunscreens in patients with broad action-spectrum photosensitivity.

The photoprotection afforded by three sunscreens available by prescription in the U.K. has been studied in patients with severe broad action-spectrum photosensitivity. All products investigated exhibited high protection against UV-B radiation in accordance with the protection factors quoted by the respective manufacturers. On the other hand, the protection against UV-A ranged only from fair to poor. The need for a sunscreen which has good protection against UV-A is shown to be important for the satisfactory management of patients with severe broad action spectrum photosensitivity.

Chronic Disease↗