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Biomedical subjects

B L Diffey

Publications and source records attributed to B L Diffey.

At least 91 records · Page 5Linked to original sources
PubMed1989

Treatment of actinic prurigo with PUVA: mechanism of action.

Five patients with actinic prurigo were treated twice weekly with PUVA. One area on the back was shielded from UVA throughout the 15-week treatment period. Before PUVA, all patients had increased erythemal sensitivity to UVA and showed abnormal augmentation of UVB erythema by topical indomethacin. After PUVA, all patients were free of photosensitive symptoms and skin that had been exposed to UVA showed normal erythemal responses. By contrast, the areas of skin that had been protected from UVA showed erythemal responses that were unchanged from pre-PUVA values. Augmentation of UVB erythema by topical indomethacin persisted, both on UVA exposed and UVA protected skin. These results show that, although PUVA is an effective treatment in actinic prurigo, it does not alter the underlying mechanism of photosensitivity. The protective effect is local and is due presumably to an increase in melanin pigmentation and epidermal thickness.

Adult↗
PubMed1989

A double-blind study of ultraviolet phototherapy in the prophylaxis of chilblains.

A randomized, double-blind study was carried out to assess the prophylactic value of ultraviolet irradiation in the autumn as a means of preventing the development of chilblains on the toes and fingers during the course of the winter. Placebo irradiation was achieved by means of an optical filter which absorbed all ultraviolet radiation from the lamps but allowed the visible light component to be transmitted, thus giving patients the impression that both limbs were being treated. Patients were reviewed at monthly intervals during the winter. The response between patients was variable; some patients developed chilblains whilst others remained symptom free. However, in no patient did the ultraviolet treated limb differ from the untreated limb. We conclude that the ultraviolet phototherapy is of no value in the prophylaxis of chilblains.

Chilblains↗
PubMed1989

A comparison of the dose-response relationship for psoralen-UVA erythema and UVB erythema.

Twenty patients with psoriasis were phototested to determine their erythemal responses to UVB and psoralen-UVA (PUVA) (oral 8-methoxypsoralen). The smallest ultraviolet radiation doses to produce erythema (minimal erythema dose and minimal phototoxic dose, respectively) were recorded and dose-response curves were constructed for UVB (24 hours after irradiation) and PUVA (48 hours) using objective measurement. The choice of a 48-hour measurement was validated by phototesting an additional 11 subjects to determine the time course of PUVA erythema. No correlation was demonstrated between minimal erythema dose for UVB, minimal phototoxic dose for PUVA, and sun-reactive skin type. The mean slope of the dose-response curve for UVB erythema was four times steeper than that for PUVA. Psoralen-UVA erythema reached a broad maximum between 48 and 96 hours after irradiation. Using objective methods we have demonstrated that the commonly accepted view of a steep dose-response relationship for PUVA erythema is not valid.

Adult↗
PubMed1989

Phototoxic potential of thiazide diuretics in normal subjects.

Monochromator phototesting has been carried out in 22 subjects before and 2 weeks after therapy with either bendroflumethiazide (bendrofluazide) or hydrochlorothiazide. An increase in erythemal sensitivity was observed in several subjects in those wave bands that are maximally absorbed by the respective drugs in vitro. Both drugs showed similar phototoxic capabilities, yet in clinical practice, reports of photosensitivity caused by hydrochlorothiazide are much more common than those caused by bendroflumethiazide. One possible reason is suggested.

Adult↗
PubMed1988

The risk of skin cancer from occupational exposure to ultraviolet radiation in hospitals.

The risk of skin cancer in subjects who are occupationally exposed to ultraviolet radiation (UVR) in hospital phototherapy departments has been estimated using a mathematical model based on age and annual UVR exposure. Measurements have shown that the median UV dose received by staff during an 8 h working day is one-fifth of the recommended maximum permissible exposure. This level of exposure increases the risk of skin cancer during a working life of 40 years by about 25% compared with non-exposed workers. Comparison with ionising radiation workers in hospitals indicates that the risk of death from an occupationally induced cancer is about 30-50 times less in UV workers.

Environmental Exposure↗
PubMed1988

The time course of UVB and UVC erythema.

The time course of ultraviolet erythema was measured using six different exposure doses of UVC and UVB radiation in each of eight adult subjects. The intensity of erythema was measured by reflectance spectrophotometry at 4, 8, 24, 36, and 48 h after irradiation. In five subjects there was no significant difference between the form of the UVB and UVC erythema time-course. In three subjects a significant difference was observed, but this was random rather than systematic between subjects. The results do not confirm the previously reported major differences in time course between the two qualities of radiation.

Adult↗
PubMed1988

The action spectrum in quinine photosensitivity.

The action spectrum for 24-h ultraviolet erythema was determined in three elderly patients who presented with a photosensitive eruption and who were taking quinine sulphate for night cramps. In each case the in vivo action spectrum was consistent with the absorption spectrum of quinine, and extended from about 370 nm to at least the lower wavelength limit of terrestrial sunlight (approximately 300 nm). Calculations based upon the combination of the action spectrum for quinine photosensitivity, the spectrum of terrestrial sunlight, and the transmission properties of various topical sunscreens, indicated that a broad absorption spectrum sunscreen would be required to provide adequate photoprotection.

Aged↗
PubMed1988

Light and length of stay in hospital.

A study was carried out to examine whether the time spent as an inpatient in hospital showed a seasonal dependence which could be attributed to differences in ambient lighting levels between summer and winter. It was found that the season of admission to hospital did not make any appreciable difference to how long patients took to recover before they were discharged.

Hospitals↗
PubMed1988

Treatment of solar urticaria with terfenadine.

Treatment with the H1 receptor antagonist terfenadine increased significantly the dose of radiation required for weal and flare formation in 5 patients with idiopathic solar urticaria. The dose of radiation required to produce immediate erythema localised to the irradiation site was unchanged by terfenadine. The weal and flare reaction in solar urticaria, but not the immediate erythema, is mediated by histamine acting on the H1 receptor.

Adult↗