Niels Bech-Thomsen

Photodynamic Therapy with Topical dL‐aminolevulinic Acid Delays UV Photocarcinogenesis in Hairless Mice

Abstract— Photodynamic therapy (PDT) with topical application of 8‐aminolevulinic acid (ALA) followed by irradiation with visible light (ALA‐PDT) is a relatively new and promising experimental treatment of superficial premalignant and malignant skin neoplasms. The purpose of this study was to determine whether ALA‐PDT can prevent photocarcinogenesis in hairless mice exposed to solar UV. A total of 140 mice was divided into seven groups of 20 mice each. Group 1: solar‐UV exposure. Group 2: solar UV and a cream base + visible light once a week. Group 3: solar UV and ALA‐PDT once a week. Group 4: solar UV and ALA‐PDT once every second week. Group 5: solar UV and ALA‐PDT every fourth week. Group 6: ALA‐PDT once a week. Group 7: no treatment. The time to first and to second tumor 1 mm was registered. Predefined endpoints, such as one tumor a 4 mm or an area of small confluent tumors on the back of the mice were criteria for withdrawal from the experiment. The time to first and to second tumor was significantly longer in the ALA‐PDT‐treated mice than in mice only exposed to solar UV and solar‐UV/cream base‐visible light (P < 0.005). However, we observed an increased death and accident rate in the ALA‐PDT‐treated groups compared to the groups not treated with ALA‐PDT (chi‐square test,P= 0.0250). Significantly more ALA‐PDT‐treated mice were withdrawn because of a tumor 4 mm (P= 0.0005). The UV unexposed mice developed no tumors. Repetitive treatments with ALA‐PDT delay photoinduced carcinogenesis in mice.

Xeroderma pigmentosum lesions related to ultraviolet transmittance by clothes

Xeroderma pigmentosum is associated with severe actinic degeneration of the skin. Our patient with xeroderma pigmentosum showed increasing actinic damage in some areas covered by clothes. We therefore performed a complete evaluation of the patients exposure to ultraviolet radiation. This included transmission measurements of the patients clothes, glasses, and car windows. The transmission of UVB (280 to 320 nm) by the clothes varied from none to 17.8%. The transmitted UVB radiation was proportional to the clinical manifestations of xeroderma pigmentosum. The patients wardrobe was changed, and UVA-blocking film was applied to the windows of the car and house. A decline in manifestations was seen after 18 months of improved ultraviolet protection.

Ultraviolet exposure influences laser-induced wounds, scars, and hyperpigmentation: a murine study.

&NA; Laser therapy is today considered the treatment of choice for vascular skin lesions, which commonly are located on the face and, therefore, frequently are exposed to sunlight. The purpose of this study was to examine whether preoperative and postoperative ultraviolet irradiation influences the development of laser‐induced side effects. We laser‐treated hairless mice with a copper vapor laser; three different intensities were used at a constant pulse duration. Simulated solar ultraviolet radiation was administered either before the laser treatment (3 consecutive days, daily doses of 2.48 J/cm2) or after the laser treatment (four times weekly in 4 weeks, daily doses of 1.66 J/cm2). Laser‐induced wounds, scars, and hyperpigmentation were evaluated by macroscopic, histologic, and biochemical examinations. Preoperative ultraviolet exposure enlarged the laser‐induced wounds and the areas with texture change at some of the laser intensities used. However, the most pronounced effect was seen for postoperative ultraviolet‐irradiated mice. These mice developed, at some of the laser intensities, a higher incidence of bulging infiltration as well as higher degrees of fibrosis and hyperpigmentation, thus developing a poor cosmetic appearance. Furthermore, ultraviolet irradiation after laser treatment resulted in slowly healing wounds of reduced size, indicating deep, constricted skin damage. We conclude that ultraviolet exposure before and after copper vapor laser treatment increases the risk of inducing side effects from dermatological laser treatment. (Plast. Reconstr. Surg. 101: 1315, 1998.)

Optimized UVB treatment of atopic dermatitis using skin reflectance measurements. A controlled, left-right comparison trial.

In a randomized, open, left-right comparison study, 20 patients with atopic dermatitis were treated with UVB. One side of the body received UVB in a conventional regimen with fixed dosage increments, the other side was given UVB dosages according to skin reflectance measurements of skin pigmentation and erythema. Clinical outcome was assessed by SCORAD. The initial, final and cumulative UVB dosages, time to 50% reduction in SCORAD, and side effects were compared. The initial UVB dosage was somewhat higher in the skin reflectance-guided treatment than in the conventional UVB regimen, although not significantly. There was no difference in the reduction of SCORAD comparing the two treatment options; however, the final UVB dosage and the cumulative UVB dosages were significantly lower in the optimized regimen. This new technique offers the same therapeutic advantage and security as a dose regimen guided by minimal erythema dose testing. However, measurement of skin pigmentation by skin reflectance is a rapid method, which can easily be operated by nurses.

8-Methoxypsoralen urticaria

Psoralens occur in many plant species from several families, and the risk of psoralen-containing food has been previously noted.v 6 Our patient had a severe allergy to 8-MOP, but this did not seem to disturb her life except for intolerance to diluted lime juice. The other reports on adverse reactions to 8-MOP have not included any comments on intolerance to naturally occurring psoralens. Therefore it is unlikely that systemic exposure to naturally occurring psoralens poses a serious problem. We observed that the patient recovered more quickly from the edema and flare during provocation than during PUYA treatment. Without irradiation 8-MOP forms a loose complex with DNA, and the concentration of 8-MOP in skin and serum deNiels Bech-Thomsen, MD, and Hans Christian Wulf, MD, DSc Copenhagen, Denmark

Optimized UVB treatment of psoriasis: a controlled, left-right comparison trial.

In a randomized, controlled, left‐right comparison study, 20 patients with chronic plaque psoriasis were treated with UVB. One side of the body received UVB in a conventional regimen with fixed dose increments, the other side was given UVB doses according to measurements of skin pigmentation. Skin pigmentation was quantified by the skin reflectance technique. The relationship between skin pigmentation and sensitivity to UV radiation was used to optimize and individualize the initial UVB exposure dose. Clinical outcome, initial, final and cumulative UVB doses, time to 50% reduction in PASI score, and side‐effects were compared. The consequence of the optimization of the UVB doses with a skin reflectance meter was that the initial UVB dose was significantly higher than in the conventional UVB regimen. PASI scoring demonstrated a more rapid improvement during the first 2 weeks of treatment on the half body receiving the optimized treatment compared to the other side (P < 0.05). This new technique offers the same therapeutical advantages and security as a dose regimen guided by minimal erythema dose testing. However, measurement of skin pigmentation by skin reflectance is a quick method which can be operated easily by nurses.

Two-day trimethoprim-sulfamethoxazole treatment of pharyngeal gonorrhea.

The efficacy of three different regimens of oral medication for pharyngeal gonorrhea was examined in a study of 119 patients. Of 34 patients treated with 1.4 g of pivampicillin plus 1.0 g of probenecid, both taken once a day for five days, 33 (97.1%) were cured. The other two regimens consisted of tablets containing sulfamethoxazole (400 mg) and trimethoprim (80 mg). Of 36 patients treated with a single ten-tablet dose on the first day, two five-tablet doses on the second day, and two three-tablet doses for the next three to five days, 35 (97.2%) were cured. Of 49 patients treated with a single ten-tablet dose on the first day and two five-tablet doses on the second day, 44 (89.8%) were cured. The cure rates for the three regimens were not significantly different (P greater than 0.05). Therefore, we conclude that a two-day trimethoprim-sulfamethoxazole regimen is quick, inexpensive, and reliable in the treatment of pharyngeal gonorrhea.

Impact of epidermal thickness on purpura from the pulsed dye laser

To clarify whether epidermal thickness is of importance to the purpuric reaction from treatment with the pulsed dye laser (PDL).