Photocarcinogenesis in mice and the effect of a sunscreen, para-aminobenzoic acid.
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4-Aminobenzoic Acid↗
Biomedical subjects
H Flindt-Hansen
Publications and source records attributed to H Flindt-Hansen.
Ultraviolet light induction of peripheral granulocytosis with splenomegaly: protection of mice with topical p-aminobenzoic acid (PABA).
Hairless mice were exposed to UVB irradiation from a Philips T1 12 light source. Mice that were exposed to UV-light and not protected with 5% p-aminobenzoic acid (PABA) showed a significantly higher number of peripheral blood granulocytes (P less than 0.001) and a significantly higher mean weight of both the spleen and the liver (P less than 0.001) than the non-irradiated controls. Light microscopy of the histology of the enlarged liver and spleen showed a proliferation of granulocytes and the reticuloendothelial cells. Treatment with topical PABA during the whole period of UV-exposure prevented the peripheral blood granulocytosis. These protected mice also had a significantly (P less than 0.001) lower mean weight for the liver and spleen than UV-exposed and non-protected mice.
4-Aminobenzoic Acid↗
Effect of a new narrow-band UVB lamp on photocarcinogenesis in mice.
Thirty lightly pigmented hairless (Hr/Hr) mice were irradiated 5 days per week for 30 weeks to assess the photocarcinogenicity of a new Philips TL 01 narrow-band (311 nm +/- 2) UVB lamp. All mice were found to be tumour-bearing after 16 weeks and histologically, 83% of these had definite squamous cell carcinomas. Compared with our previous study where conventional broad-band Philips TL 12 UVB irradiation was used, tumours appeared earlier with the TL 01 lamp. The total irradiation dose was, however, several times greater in the TL 01 assay while the total MED dose was considerably less.
Animals↗
The inhibiting effect of PABA on photocarcinogenesis.
The efficacy of a 5% solution of para-aminobenzoic acid (PABA) to protect against photocarcinogenesis was tested in 6 groups, each of which contained 30 light pigmented hairless mice. The light source was a Phillips TL 40 W/12, which mainly emits UVB. PABA significantly retarded the tumor induction time (p less than 0.05) and reduced both tumor yield and carcinoma yield (p less than 0.05). The dorsal skin of the mice was removed and weighed. The mean weight of UVR-exposed mice skin protected with PABA did not differ from that of the controls, but in the non-protected UVR-exposed mice the skin samples were significantly heavier (p less than 0.05).
4-Aminobenzoic Acid↗
The effect of short-term application of PABA on photocarcinogenesis.
Photocarcinogenesis was induced in 90 lightly-pigmented hairless mice using a Philips Tl 40 W/12 light source which emits mainly UVB (290-320 nm). During one-third of the induction period (weeks 16-26) a group of 30 mice were protected by topical para-aminobenzoic acid (PABA) and then irradiated again without protection up to week 30 and observed for a further 10 weeks. The application of PABA resulted in a significant delay (p less than 0.05) in tumour induction and discontinuation of PABA caused an abrupt decline in the number of tumour-free animals. At the end of the study there was a significant difference in the yield of carcinomas for the PABA group, 20, compared with 78 for non-protected mice (p less than 0.05). There was also a statistically significant difference (p less than 0.05) between the weight of dorsal skin in non-protected mice compared with the PABA-protected group, the latter showing no difference from a control group of non-irradiated mice. The proportion of benign tumours in the PABA group was significantly (p less than 0.05) higher than in the non-protected group, suggesting an inhibition of the photo-carcinogenic process.
4-Aminobenzoic Acid↗
Photocarcinogenesis is retarded by a partly photodegraded solution of para-aminobenzoic acid.
A solution of para-aminobenzoic acid (PABA) was exposed to ultraviolet (UV) radiation emitted from a Philips TL 40 W/12 sunlamp and the degree of photodegradation following an exposure of 27 J/cm2 was estimated to be approximately 40%. The formation of the photoproducts was confirmed by mass spectroscopy and UV spectroscopy. The solution was painted on the backs of hairless light-pigmented mice prior to daily UV irradiation by the above sunlamp, and this procedure was continued for 30 weeks. The preirradiated solution of PABA significantly retarded the tumor induction time and reduced significantly the number of squamous cell carcinomas compared with nonprotected controls. This tumor-retarding ability did not differ significantly from the effect achieved when using nonirradiated PABA.
4-Aminobenzoic Acid↗
Measurements of the photodegradation of PABA and some PABA derivatives.
The photodegradation of 4-aminobenzoic acid, 2-ethylhexyl N,N-dimethyl 4-aminobenzoate (Escalol 507) and 1-glyceryl 4-aminobenzoate (Escalol 106), resulting from irradiation by sun lamps, was examined by UV spectroscopy. 2-ethylhexyl N,N-dimethyl 4-aminobenzoate showed the longest half-life, indicating the highest photostability.
4-Aminobenzoic Acid↗
Scleroderma after occupational exposure to trichlorethylene and trichlorethane.
Three cases of scleroderma, developed after occupational exposure to trichlorethylene and trichlorethane are described. The question is raised whether exposure to these chlorohydrocarbon solvents may be an etiological factor.
Adult↗
Malignant melanoma associated with mycosis fungoides.
2 cases of malignant melanoma in 2 male patients, 68 and 63 years old, associated with mycosis fungoides and parapsoriasis en plaques, respectively, are reported. The parapsoriasis later on developed into mycosis fungoides. A pathogenetic linkage based on decreased cellular immunity in mycosis fungoides is suggested.
Aged↗
Wart treatment with anthralin.
In order to investigate the efficacy of anthralin ( Anthraderm ) in the treatment of warts a randomized controlled trial was carried out in 72 patients. During a two-month period of treatment 56% were cured in the group treated with anthralin 2% ( Anthraderm ), evaluated at follow-up 2-9 months after finishing treatment, compared with 26% in the group treated with the comparative drug ( Verucid ). Anthralin 2% ( Anthraderm ) was found to have a significantly better effect, especially in the group of patients with warts solely on the hands.
Adolescent↗