Photo-dermatology最新文献

Urocanic acid has been postulated as the photoreceptor mediator of immunosuppression induced by ultraviolet-B (UVB) irradiation. We have shown previously that transplanted epidermal cells from neonatal mice, irradiated mice or mice skin painted with cis-urocanic acid suppress the immune responses to herpes simplex virus. Dorsal skin from foetal mice at 3 weeks gestation and from neonatal mice within 1 day of birth were assayed for the presence of cis- and trans-urocanic acid and compared with the amounts in the ears of 2, 4, 6 and 8-week old mice. Foetal mice had a low skin urocanic acid content (11.9 ng/mg wet weight), neonatal mice 227 ng/mg, while the other ages had at least 340 ng/mg. Neonatal mice were found to have 11.4% urocanic acid as the cis-isomer, whereas foetal mice had undetectable amounts and all remaining ages had about 4%. Irradiation of 7-week-old mice with 96 mJ/cm2 UVB light resulted in the presence within the ears of 31.1% urocanic acid as the cis-isomer. This level was maintained for at least 16 h, then declined slowly until, after 7 days, 16.2% was in the cis-form. Nonirradiated ears contained 4.7% cis-isomer. It is known that UVB irradiation of mice suppresses the delayed type hypersensitivity response to HSV. The suppression was found to be dependent on the time interval between irradiation and infection with virus; this had to be longer than 5 h and less than 14 days.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of single doses of ultraviolet (UV) radiation was studied in 6 healthy men of skin Type III. Test areas on the forearm were irradiated with 150 J/cm2 UVA, 0.5 MED, 1 MED, and 3 MED UVB, and 1 MED UVC. Test areas and control areas were followed up for 1 month by clinical assessment, laser-Doppler flowmetry, evaporimetry, and optothermal infrared spectrometry (OTIS). UVA produced immediate erythema; the reaction appeared later with the other wavelength regions. All responses peaked after 12-24 h. The degree of erythema of UV-induced inflammation assessed visually correlated closely with the increase in skin blood flow registered with the laser-Doppler flowmeter. No increase in transepidermal water loss, indicating damage to the epidermal barrier, could be recorded by evaporimetry except on the area irradiated with 3 MED of UVB, where 4 subjects showed a moderate increase after 2 weeks. Changes in water content in the uppermost part of the epidermis, mainly in the stratum corneum, were detected by OTIS. A decrease took place that was most pronounced in the area irradiated with 3 MED UVB. This decrease in the OTIS signal is probably due to a combination of increased thickness and decreased water content of stratum corneum. We believe that these 3 noninvasive methods, especially in combination, are useful in the evaluation of different aspects of UV reactions.

High-purity glyceryl para-aminobenzoate was produced from a commercial source of the chemical by using a chromatographic technique. Negative test reactions to this purified substance were obtained when it was patch/photopatch-tested on 2 patients with contact and photocontact allergy to a nonpurified batch of glyceryl para-aminobenzoate.

A 17-year-old male with solar urticaria is described. The action spectrum ranged from 400 to 520 nm. Wheals induced by visible light were inhibited by simultaneous or subsequent irradiation of the skin with UVA radiation. UVA irradiation prior to exposure to eliciting wavelengths revealed no inhibitory effect, nor was an inhibitory effect found by pre- or postirradiation of test sites with visible light longer than 530 nm. In vitro activation of the patient's serum by exposure to visible light induced wheal formation at the injection site. The wheal formed by in vitro-activated serum was suppressed only when the serum was exposed to UVA after, but not before irradiation with wavelengths of the action spectrum. This suggests that the inactivation of a photoallergen rather than of its precursor is the mechanism by which UVA exerts an inhibitory effect.

Clinical photoreactions have been reported for quinine and quinidine after systemic and topical administration. We have investigated the phototoxic properties of these two quinoline methanol isomers in vitro using the Candida albicans inhibition test and photohemolysis, and in vivo with the mouse tail phototoxicity test. Both isomers were phototoxic in the hemolysis model, quinine being the more potent compound. In the Candida test only quinidine was phototoxically active. In the mouse tail model, measuring edema, the phototoxic activity of quinidine was comparatively low, causing a 7.3% wet weight increase of tail tissue at a dose of 150 mg/kg intraperitoneally of drug and 54 J/cm2 of UVA. In spite of its structural similarity to quinidine, quinine was not phototoxic in the mouse. These studies support the assumption, based on clinical data, that quinine photoreactions probably have a non-phototoxic mechanism. For quinidine, however, light-induced reactions based on phototoxicity can not be ruled out, since low-grade phototoxic properties were demonstrated in vivo.

Action spectra for UV erythema and reproduction of the skin lesions in 4 patients with hydroa vacciniforme (HV) were studied. Vesicles were successfully reproduced by repeated daily monochromatic irradiations of 330, 340, 350 and 360 nm for 5, 6 or 7 days. The daily doses were equivalent to global solar radiation for 70-190 min. The vesicles produced were identical to those of HV, macroscopically and histologically. Repeated daily exposures to a small dose of UVA produced vesicles, whereas a large but single exposure to UVA failed to do so. Daily exposures to UVB failed to produce the vesicles. The minimal erythema dose (MED) was lower than the minimum limits of the normal persons in the 290-310 nm range.

This study evaluated the Langerhans cell density in chronically sun-exposed skin (hand) and non-exposed skin (buttock) in subjects that were divided into 4 age groups (20-40; 41-60; 61-80; greater than 81 years). Two markers (OKT-6 and anti-HLA-DR) were used to identify the Langerhans cells (LC), and their count was performed either on epidermal sheets (52 individuals) or skin sections (43 individuals). Three major findings result from this study: 1) there are more LC in the non-exposed skin than in the chronically sun-exposed area; 2) there were no age-related changes in LC counts, and 3) LC co-express the T6 and HLA-DR antigens.