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Biomedical subjects

B L Diffey

Publications and source records attributed to B L Diffey.

At least 109 records · Page 6Linked to original sources
PubMed1984

Quantitative studies on cutaneous erythema induced by ultraviolet radiation.

A reflectance instrument was used to measure the variation in UVR-induced erythema at different positions on the back. The pre-irradiation erythema index decreased from top to bottom of the back but the increase in index remained constant for a fixed exposure dose. In contrast, the minimal erythema dose was higher at lower sites on the back. The measured erythemal response increased linearly with the logarithm of the radiation dose from approximately the minimal erythema dose up to at least fifteen times this value.

Adult↗
PubMed1984

Clinical climatology.

An appreciation of the influence of environmental factors regarding the quality and quantity of terrestrial ultraviolet radiation (UVR) is important when trying to optimize the conditions for climatic therapy of skin diseases or in order to minimize the harmful effects of the sun. The time of day, season of the year and geographical latitude all have strong influences on the amount of UVB energy reaching the surface of the Earth. For example, it is important to realize that there be may be more sunburning UVB around on a moderately cloudy day at midday than on a clear day in the late afternoon. Other factors, such as reflection from the ground, are also important. A common misconception is that water reflects much of the incident ultraviolet radiation. In fact water and a green grass lawn have about the same reflectance. Furthermore, the erythemal effectiveness of sunlight is actually greater in the autumn than in the spring due to a thinner ozone layer. Some of the factors described above are often neglected when we advise patients about their sunlight exposure.

Altitude↗
PubMed1984

A preliminary study on the in vivo transmission of light through psoriatic plaques.

The transmission of light through psoriatic plaques has been measured in vivo using a quartz fiber before and after the application of the lipophilic liquid, glycerin. The results indicated a roughly two-fold increase in transmission following the application of glycerin. This was achieved after a period which ranged from 3 to 15 min suggesting a diffusion process. The main problem encountered was bleeding which led to satisfactory data being obtained in only 3 out of 6 patients investigated.

Adult↗
PubMed1983

The UVB content of 'UVA fluorescent lamps' and its erythemal effectiveness in human skin.

The UVB emission from ten different types of 'UVA fluorescent lamp' has been measured by spectroradiometry. The mean ratio of UVB emission to UVA emission was found to be 0.94 +/- 0.35 (1 SD)%. By weighting the spectral irradiance of each lamp by the DIN standard erythemal curve, the mean erythemally effective UVB emission (normalised to 297 nm), expressed as a percentage of the UVA emission, was 0.076 +/- 0.049 (1 SD)%.

Erythema↗
PubMed1983

A mathematical model for ultraviolet optics in skin.

A new approach to calculating the transmission and reflection of ultraviolet radiation from skin is described. The method is based upon a numerical solution of the equation governing radiation transport in matter. By comparing the calculations with experimental measurements of the optical properties of human skin described elsewhere, it has been possible to derive absorption and scattering coefficients for stratum corneum. The model has been used to investigate the photoprotective function of the thickness and melanin content of stratum corneum, and yields results which concur with experimental studies on the ultraviolet optics of stratum corneum carried out by other workers.

Humans↗
PubMed1983

Phototoxic reactions to piroxicam, naproxen and tiaprofenic acid.

Photosensitivity investigations have been carried out using an irradiation monochromator on 31 patients taking one of seven different nonsteroidal anti-inflammatory agents for the treatment of rheumatoid and osteoarthritis. Six patients, who were taking either piroxicam, naproxen or tiaprofenic acid, experienced adverse immediate reactions of erythema and flaring, together with an urticarial response in four of these six patients. No phototoxic response was observed in patients taking either indomethacin, ketoprofen, benorylate or ibuprofen, although firm conclusions about the non-phototoxic nature of these four drugs cannot be drawn from this pilot study because of the small numbers of patients investigated.

Anti-Inflammatory Agents↗
PubMed1983

A method for predicting the phototoxicity of non-steroidal anti-inflammatory drugs.

The photosensitisation potential of several non-steroidal anti-inflammatory drugs (NSAIDs) has been investigated in vivo using an irradiation monochromator. Evidence of abnormal, immediate photosensitivity was obtained in 13 of the 38 patients taking one of four out of seven different NSAIDs. A simple mathematical model was developed to predict the likelihood of photosensitivity occurring with a given drug by considering the mass of drug normally ingested, the spectral absorption characteristics of the drug, and the quantity and spectral quality of the radiation (e.g. sunlight) to which the patient may be exposed.

Anti-Inflammatory Agents↗
PubMed1983

Reappearance of epidermal Langerhans cells after PUVA therapy.

Epidermal Langerhans cells (LC) disappear during photochemotherapy (PUVA) with 8-methoxypsoralen (8-MOP) and long wavelength ultraviolet (UV-A) radiation. The time course of their disappearance during treatment and their reappearance after its completion was followed. Langerhans cells lost ATPase activity before they disappeared by ultrastructural criteria: thus 90% of ATPase-stained cells had disappeared after seven treatments (2 weeks) whereas it was only after fifteen treatments (5 weeks) that they were seen to be reduced on electron microscopy. Their numbers remained low throughout the course of treatment but they had returned to normal by 3 weeks after cessation of therapy. Since PUVA lamps also emit traces of medium wavelength UV (UV-B) the separate effects of UV-A and UV-B in the presence and absence of 8-MOP were examined. Within the dose range normally used for therapy, the LC disappeared only with the combination of UV-A and 8-MOP.

Adenosine Triphosphatases↗
PubMed1983

The transmission of optical radiation through human nails.

The transmission of optical radiation in the wavelength range 300-600 nm through thirteen human toenails obtained at autopsy was examined. The total transmitted radiation at fifteen different wavelengths was measured using an irradiation monochromator in conjunction with an integrating sphere and photodiode. A correction was included for fluorescence radiation from the nails. The nails exhibited decreasing transmission of optical radiation in the wavelength region 600-300 nm. These findings may be helpful in the understanding of photo-onycholytic reactions and in the design of suitable regimens for the treatment of psoriatic nail changes.

Humans↗
PubMed1983

A placebo-controlled trial of UV-A phototherapy for the treatment of uraemic pruritus.

The effect of ultraviolet A phototherapy on uraemic pruritus was investigated in a placebo-controlled trial. Equivalent and significant reduction of itch was noted in both placebo and treatment groups as assessed by analogue scales and interviews. This reduction in itch could have been the result of either a placebo response or a biological effect of blue light.

Chronic Disease↗