BACKGROUND/PURPOSE: The sunless tanning agent dihydroxyacetone (DHA) is known to protect against longwave ultraviolet radiation (UVA) and visible light. Recently, our laboratory has shown that DHA in addition offers a modest sun protection factor (SPF) in humans. We conducted this study in order to investigate the durability of the SPF provided by DHA. METHODS: Ten healthy volunteers were treated with 20% DHA cream twice in three areas on the volar forearm. One, 5 and 7 days after the second application the participants were phototested with simulated sunlight in each area. Blue reflectance was used to measure the skin coloration by DHA in the test sites. RESULTS: DHA generated a significant SPF of 3.0 at day 1, 2.0 at day 5 and 1.7 at day 7 (P<0.0001). The SPF was positively correlated to the change in blue reflectance (r=0.39, P=0.034). The loss of SPF unit/day was not significantly different between the subjects (P<0.122). However, the intercepts were significantly different (P<0.0001) indicating differences in the initial SPF obtained among the subjects. CONCLUSIONS: The SPF of DHA decreases with the same loss of SPF unit/day between humans and the durability of the SPF thus depends on the initial SPF provided. 相似文献
Background: Ultraviolet (UV)A protective properties of dihydroxyacetone (DHA) have been used as a topical UV‐resisting barrier to optimize psoralens and UVA (turbo‐PUVA). Starting doses and increments were based on the DHA diffuse reflectance spectroscopy‐derived protection factor. Objective: To evaluate the efficacy of turbo‐PUVA in psoriatic patients using a simpler method for determining starting doses and increments, in comparison to the conventional American‐style PUVA photochemotherapy. Methods: Thirty psoriasis patients (15 on American‐style PUVA and 15 on turbo‐PUVA) were evaluated, each receiving PUVA twice weekly. Starting UVA dose was determined according to skin phototype for the American‐style PUVA group and according to the patient's skin phototype × DHA SPF 3 in turbo‐PUVA group. UVA increments used were 0.5–1.5 J/cm2 per treatment in American‐style PUVA and 25% of the previous dose in turbo‐PUVA. Results: Turbo‐PUVA group showed a significantly lower mean cumulative dose, a significantly higher psoriasis area and severity index score reduction, lesser mean number of treatment sessions, and less duration of treatment till remission (188.44±106.2 J/cm2, 92.164±1.975%, 11.2±3.52 session, and 1.4±0.44 months, respectively) than conventional American‐style PUVA group (255.13±18.304 J/cm2, 74.725±10.976%, 30±0.00 sessions, and 3.75±0.00 months, respectively). Conclusion: Turbo‐PUVA is more effective and time convenient for the treatment of psoriasis with less cumulative dose than the conventional American‐style PUVA. 相似文献
We studied the influence of substrates and glycolysis inhibitors on the release of proteins and enzymes from human leukocytes. We show the relationship between metabolic level and percentage of enzyme release.Leukocyte kept alive in a nutrient-free bicarbonate medium liberate enzymes even though their metabolic state is satisfactory. The addition of glucose to the medium significantly decreases this phenomenon without affecting the energy level. Addition of glycolysis inhibitors increases it, reduces the energy level, and interferes with other metabolic pathways.The results are discussed and compared to those obtained by other authors using various cell models. 相似文献
We present details of a patient who was demonstrated to have contact allergy to a solution used to mark sites of application of patch tests, during investigation of allergy to gold and nickel. Negative results were obtained when patch testing was performed using the individual constituents of the marker solution (gentian violet, dihydroxyacetone and acetone). Chromatographic analysis of various combinations of these chemicals did not identify a chemical derivative which might have caused this reaction. 相似文献
Mechanisms by which clofibrate decreases the development of acute alcoholic fatty liver were studied, especially in regard to hepatic redox state and hormonal regulation of carbohydrate and lipid metabolism. A partial inhibition of the ethanol-induced increase in cytosolic NADH/NAD ratio was observed. As a result, in clofibrate-treated rats hepatic α-GP concentration during ethanol oxidation also remained at the same level as in normal control rats. Clofibrate treatment prevented the ethanol-induced increase in the adipose tissue cAMP and plasma FFA concentrations. Hepatic concentrations of CoA-SH, acetyl-CoA and long chain acyl-CoA were markedly increased by clofibrate treatment. Plasma insulin concentration was decreased in clofibrate-treated rats, which also showed an impaired glucose tolerance. The results show that clofibrate is able to restrict the availability of substrates (α-GP and fatty acids) for hepatic triglyceride synthesis in vivo. In addition, it was concluded that the partial inhibition of ethanol-induced fatty liver by clofibrate may result from the enhancement of the oxidation pathway of fatty acid metabolism as suggested by the enormous increase in hepatic content of CoA-SH and its derivatives. 相似文献
Biodegradable hydrogels are an important class of biomaterials with a diverse range of applications. In some cases, a rapid hydrogel degradation rate is advantageous. Polycarbonate hydrogels based on dihydroxyacetone (DHA), a natural metabolite, have been reported to undergo surprisingly fast hydrolytic degradation. In the present work, insight into the key features of DHA that contribute to the observed degradation rates is gained. In vitro degradation (mass loss) of three different chemically cross‐linked polycarbonate hydrogels is investigated to shed light on the role of the ketone functional group, as well as the carbon‐chain length between the ketone and carbonate bonds. The ketone is found to be the major cause of rapid degradation. Also, mass loss is accelerated by increased temperature and pH, offering insight into potential tuning parameters and storage conditions. The results show that DHA is a promising monomeric unit for the design of rapidly degrading, biocompatible, and functional biomaterials.