Search

Background Topical preparations such as emollients used in combination with phototherapy can interfere with such treatment. Objectives This study was performed to investigate the impact of vaseline on the ultraviolet (UV) transmission of non-irradiated split skin and on split skin previously exposed to UVB radiation. Methods Split-skin specimens were obtained from 20 patients. In each case, one sample was taken from an area of non-irradiated skin, while the second was taken from an area that had been previously exposed to UVB. The transmission was spectrophotometrically measured with split skin placed in specially designed quartz glass cuvettes before and after the application of two different amounts of vaseline (2.5 and 17.5 mg cm -2 ). Results Application of vaseline to skin previously exposed to UVB caused significant (P < 0.0001) changes in UV transmission in certain wavelength ranges. In the UVA range, a greater increase in transmission was achieved with 2.5 mg cm -2 vaseline, whereas in the UVB range, a greater increase was achieved with 17.5 mg cm -2 vaseline. The thicker the layer of vaseline applied, the lower was the difference in transmission between non-irradiated split skin and UVB-exposed split skin. Conclusions Application of the correct amount of vaseline can enhance transmission in either the UVA or UVB range, and would enable dose reduction during a course of phototherapy.

A survey, using a postal questionnaire, was carried out to examine the current practice of UVB phototherapy in dermatology centres in the U.K. The questionnaire was sent to 115 dermatology departments, and sought information regarding the type and age of each machine used for ultraviolet B (UVB) phototherapy, methods of prescribing, recording and terminating patient exposure, and the skin conditions treated. Completed questionnaires were received from 87 of the 115 centres, giving a response rate of 76%. The survey showed that an appreciable number of U.K. phototherapy centres are using equipment which is both old, and suboptimal in producing a therapeutic response. There appeared to be a wide variation in the approach to phototherapy, both in terms of prescribing initial and incremental exposure, and in terminating treatment. The findings suggest that effectiveness and efficiency might be improved, and the risk/benefit ratio of phototherapy further reduced, by some rationalization of treatment protocols.

In PUVA treatment of psoriasis, clinical observation suggests that uninvolved skin is more susceptible to PUVA erythema than lesions of psoriasis. If this is the case, then the efficacy of PUVA treatment might be increased by using localized high-dose UVA restricted to lesional skin. We have therefore studied the erythemal and therapeutic response of psoriasis to PUVA using high-dose UVA and, for comparison, the erythemal response to UVB. In 14 patients, an area of psoriasis and adjacent uninvolved skin were exposed to a series of UVA doses (350 +/- 30 nm, 1-16J/cm2), using an irradiation monochromator. Six other patients were similarly phototested with a series of UVB doses (300 +/- 5 nm, 20-112 mJ/cm2) to both uninvolved and lesional skin. Erythema was judged visually at 72 h for psoralen-UVA, and at 24 h for UVB, and measured using a scanning laser-Doppler velocimeter. In 10 patients, PUVA therapy using high-dose UVA was subsequently given to lesional skin (8-16J/cm2 twice weekly) in addition to conventional whole-body PUVA. For psoralen-UVA, the minimal phototoxic dose within psoriasis was increased by a factor of 4 compared with non-lesional skin (P0.01, Wilcoxon signed-rank test). For UVB, the minimal erythema dose within psoriasis was higher than that for non-lesional skin (medians112 and 28 respectively, P0.05). Laser-Doppler measurements confirmed that the reduced erythemal sensitivity was not due to masking of response by pre-existing increased blood flux within psoriasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Summary In a left-right comparative study, the Philips TL-01 sunlamp, a new UVB fluorescent lamp, was evaluated in 15 patients with symmetrical psoriasis. One half of the body was treated in a cabin containing TL-01 lamps, and the other half in a cabin containing TL-12 lamps. The patients were treated three times/week, and the study was conducted in a randomized, double-blind fashion. The percentage response of psoriatic lesions was determined on the tenth and twentieth exposures. The therapeutic effect of the TL-01 lamps was superior to that of the TL-12 lamps, and treatment was better tolerated, particularly with regard to episodes of burning. This new lamp appears to provide more effective and safer phototherapy for psoriasis.

We have compared the therapeutic effectiveness of a new UVB fluorescent sunlamp, the Philips TL-01 lamp, which emits a narrow peak around 311-312 nm, with the currently used Philips TL-12 lamp, in 10 patients with psoriasis. We also compared the tumour inducing capacity of the two lamps in hairless mice. The therapeutic effect of the TL-01 lamp was superior to that of the TL-12 lamp in nine of the 10 patients. In the mice, the median tumour induction time was significantly longer in animals exposed to the TL-01 lamp. Phototherapy with the new type of lamp requires a higher dose than phototherapy with the usual broadband UVB sources. In practice this means that more lamps are needed in the light cabinet. However, the new lamps appear to provide more effective and safer phototherapy for psoriasis.

Summary Guinea-pigs were sensitized by percutaneous application of dinitrochlorobenzene and exposed to UVA (320–400 nm) radiation following systemic administration of methoxsalen. This treatment diminished the response to an elicitation dose of the hapten administered 14 days later within the site of irradiation. The site of elicitation of the allergic response had to be included in the field of exposure, and reduction of the allergic response was observed only when the exposure to radiation was commenced at the time of induction of contact allergy. Established contact skin sensitivity was not affected by radiation.

SUMMARY The erythemal response of normal human skin to UVA and UVB radiation was measured objectively using a reflectance instrument in seven subjects, and a laser Dopplcr velocimeter in two subjects. UVA radiation was produced using a newly-developed high-intensity UVA lamp. The slope of the log dose-erythemal response curve for UVA at 24 h after irradiation was found not to differ significantly from that for UVB. The time course of UVA erythema was biphasic; erythema was present immediately after irradiation, fell to a minimum at about 4 h and then rose to a broad plateau between 6 and 24 h. The intensity of the early phase was dose-rate dependent, whereas that in the later phase depended on dose only.