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Selected AbstractsInfluence of light energy and power density on the microhardness of two nanohybrid compositesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2008Kerstin Gritsch The purpose of this study was to investigate the role of light parameters on nanohybrid composite curing. Two nanohybrid resins were cured by two light-emitting diode (LED) devices and by one quartz-tungsten-halogen (QTH) device using different combinations of energy density and power density (8 J cm,2 and 400 mW cm,2; 8 J cm,2 and 1,000 mW cm,2; 16 J cm,2 and 400 mW cm,2; and 16 J cm,2,1,000 mW cm,2). The effects of these combinations on polymerization were assessed by measuring the Vickers microhardness. Data differed for the two composites and varied according to the light parameters and the nature of the curing device. For both resins, an energy density of 16 J cm,2 yielded the best microhardness values at both the top and the bottom of the sample, independently of the power density. When using a lower energy density of 8 J cm,2, a modulated power density was required to achieve proper curing at the bottom of the sample: 8 J cm,2 and 400 mW cm,2 induced greater values at the bottom surface. At an energy density of 16 J cm,2, the power density was not relevant (no significant differences were found between 400 and 1,000 mW cm,2), except when the emission spectra of the light-curing units (LCUs) did not match exactly with the absorption spectra of the photoinitators included in the resins (greatest values with 16 J cm,2 and1,000 mW cm,2). These results suggest that above a certain energy density threshold, the power density may not significantly influence the polymerization kinetics. [source] Effects of ultraviolet radiation on the eggs of landlocked Galaxias maculatus (Galaxiidae, Pisces) in northwestern PatagoniaFRESHWATER BIOLOGY, Issue 3 2000M. Battini Summary 1Ultraviolet radiation (UVR) damages early life stages of several fish species. Galaxias maculatus is a small catadromous fish, with landlocked forms occurring in many lakes within the Nahuel Huapi National Park (Patagonia, Argentina). In this work, the vulnerability of G. maculatus eggs exposed to both natural and artificial UVR was investigated in relation to water transparency. 2Field experiments were performed in two lakes differing in UVR attenuation. Galaxias maculatus eggs were exposed to in situ levels of UVR in quartz tubes incubated at various depths. For laboratory experiments, the eggs were exposed to five levels of artificial UVB radiation. 3Exposure to natural UVR causes various degrees of egg mortality depending on water transparency and incubation depth. In the less transparent lake (Kd320 = 3.08 m -1), almost complete mortality was observed near the surface. At a depth of 43 cm the observed mortality was only 22%, but was still significantly different from the dark control. In the most transparent lake (Kd320 = 0.438 m -1), almost total mortality was observed in tubes incubated at 2.56 m or shallower. A gradual decline in mortality was recorded from that depth to 3.78 m where the values approached those in the dark control treatments. 4A monotonic relationship between mortality and UV exposure could be observed both in field and laboratory experiments. Using the results from field incubations, a LD50 of 2.5 J cm -2 nm -1 was estimated. In a few mountain lakes, this value would be exceeded even if the eggs were laid at the maximum depth of the lake. Thus UVR seems a sufficient cause to explain the absence of G. maculatus populations in some mountain lakes. For most lakes, however, UVR is probably one of several important environmental factors, which together determine the habitat suitability. [source] 2-Ethylhexyl-2,4,5-trimethoxycinnamate and di-(2-ethylhexyl)-2,4,5-trimethoxybenzalmalonate as novel UVA filtersJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2007Thitinun Monhaphol A series of 2-ethylhexylmethoxy substituted cinnamates and benzalmalonates have been synthesized and characterized. 2-Ethylhexyl-2,4,5-trimethoxycinnamate (E8) and di-(2-ethylhexyl)-2,4,5-trimethoxybenzalmalonate (B8) show UVA absorption with high molar absorption coefficients (12000-14000 cm,1 M,1 at 350 nm). E8 undergoes trans to cis photoisomerization under UVA exposure causing the decrease in UV absorption efficiency. E8 is more photostable than butyl methoxydibenzoylmethane (BMDBM). For example, 41.64 J cm,2 UVA irradiation produces 20 ± 2% and 25 ± 2% loss in UV absorption for E8 and BMDBM, respectively. Similar irradiation produces no change in the UV absorption of B8. Both the oily liquid E8 and the yellow solid B8 can be dissolved in various organic solvents, ranging from methanol to hexane, various silicone fluids and 2-ethylhexyl-4-trimethoxycinnamate (EHMC, a widely used UVB filter). A liquid broadband filter comprising B8 and EHMC shows excellent photostability in both UVB and UVA regions. [source] Effects of repeated low-dose UVB irradiation on the hyphal growth of Candida albicansMYCOSES, Issue 1 2006J. Brasch Summary Ultraviolet B light (UVB) can have negative phototropic effects on fungi. Candida albicans is often found on human skin exposed to UVB. Therefore, it is of medical interest to know whether a negative phototropic response to UVB irradiation can support an invasive growth of this potentially dangerous agent. In our study we investigated how repeated irradiation with low doses of UVB can influence the hyphal growth of C. albicans. Six randomly chosen strains of C. albicans were tested. Formation of hyphae was induced and maintained within transparent agar plates. The fungi were exposed to UVB three times daily for 7 days from either the obverse or the reverse side during incubation. The wavelength spectrum was in the range of 310,315 nm, single doses were between 0.0018 and 0.432 J cm,2. After 7 days the morphology and growth direction of C. albicans cells were determined microscopically. All six strains showed a common and dose-dependent response to UVB irradiation: the progression of hyphal growth was inhibited, no phototropic effects were seen and as a new finding an increased formation of blastospores was observed. We conclude that an irradiation of human skin colonized by C. albicans with doses of UVB that can occur under natural or artificial conditions is unlikely to trigger skin invasion by C. albicans. [source] AlamarBlue bioassay for cellular investigation of UV-induced crystalline lens damageOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 4 2003Olanrewaju M. Oriowo Abstract Purpose: The use of the alamarBlue fluorescence dye for cellular study of UV-induced photodamage in cultured ocular lenses was examined by comparing the results from the fluorometric assay to lens optical quality using a scanning laser system to measure the focal lengths of the lenses following UVB treatment. Methods: Excised porcine lenses were cultured in M199 supplemented with 1% antibiotics and 4% porcine serum. After 1 week of pre-incubation at 37°C, baseline measurements were taken. Treated lenses were irradiated with a range of UVB radiant exposures from 0.019 to 0.076 J cm,2. The lenses were maintained for a further 4 weeks, with measurements carried out every 48 h in the first 9 days post-UVB treatment and then once each week. At each measurement session, treated and control lenses were transferred into a 24-well plate, one lens per well containing the assay. The lenses were incubated for 50 min, after which fluorescence readings were taken with a plate reader. Results: Analyses showed significant (p < 0.05) inhibition of lens metabolic activity and optical function in the 0.038 and 0.076 J cm,2 UVB treated lenses. Lenses treated with 0.019 J cm,2 UVB did not exhibit any photodamage. Conclusions: These results suggest that the alamarBlue assay is useful for the in vitro study of UV-induced lens damage. The decrease in the capacity of treated lenses to reduce alamarBlue over time confirms that UVB photo-oxidation can cause diminution of viable lens epithelial and fibre cells. The results also suggest that the energy threshold for broadband UVB induced cataractogenesis in vitro ranges between 0.019 and 0.038 J cm,2. [source] Detection and Prevention of Ocular Phototoxicity of Ciprofloxacin and Other Fluoroquinolone Antibiotics,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2010Baozhong Zhao Fluoroquinolone (FLQ) drugs are a potent family of antibiotics used to treat infections including ocular infections. To determine if these antibiotics may be phototoxic to the eye, we exposed human lens epithelial cells to 0.125,1 mm FLQs (ciprofloxacin [Cipro], lomefloxacin [Lome], norfloxacin [Nor] and ofloxacin [Ofl]), the precursor quinolone nalidixic acid (Nalid) and UVA radiation (2.5 J cm,2). Based on fluorescence confocal microscopy, FLQs are diffused throughout the cytoplasm and preferentially located in the lysosomes of lens epithelial cells. Neither FLQ exposure alone nor UVA exposure alone reduced cell viability. However, with exposure to UVA radiation the FLQs studied (Cipro, Nor, Lome and Ofl) induced a phototoxic reaction that included necrosis, apoptosis, loss of cell viability as measured by MTS, and membrane damage as determined by the lactate dehydrogenase assay. Both Nalid and all FLQs studied (Cipro, Nor, Lome and Ofl) photopolymerized the lens protein ,-crystallin. Phototoxic damage to lens epithelial cells and/or ,-crystallin will lead to a loss of transparency of the human lens. However, if precautions are taken to filter all UV radiation from the eye while taking these antibiotics, eye damage may be prevented. [source] The Neovessel Occlusion Efficacy of 151 -Hydroxypurpurin-7-Lactone Dimethyl Ester Induced with Photodynamic TherapyPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2010Siang Hui Lim In this study, the photodynamic therapy (PDT) induced efficacy of a semi-synthesized analogue 151 -hydroxypurpurin-7-lactone dimethyl ester or G2, in terms of chick chorioallantoic membrane blood vessel occlusion was evaluated in reference to verteporfin. Early formulation studies showed that G2 prepared in a system of cremophor EL 2.5% and ethanol 2.5% in saline was biocompatible up to 20 ,L volume of injection. Following injection, G2 accumulation peaked within the first minute and its extravasation from intra- to extra-vascular occurred somewhat slower as compared with verteporfin. In the PDT study, closure of capillaries and small neovessels was observed with 4 ,g per embryo of G2 and a light dose of 20 J cm,2 at a fluence rate of 40 mW cm,2 filtered at 400,440 nm,a result that may be considered optimum for the treatment of age-related macular degeneration (AMD). Also, partial occlusion of the large vessels was observed using the same dose of G2 and light,an effect which is desirable for cancer treatment. From this study, we conclude that G2 has the potential to be developed as a therapeutic agent for photodynamic treatment for AMD and cancer. [source] Cationic Hypericin Derivatives as Novel Agents with Photobactericidal Activity: Synthesis and Photodynamic Inactivation of Propionibacterium acnesPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2009Beate Hager The present communication describes for the first time the synthesis and preliminary testing of two cationic hypericin derivatives. Uncharged hypericin derivatives with ,,,'-attached C2 -linkers leading to a pyridyl or a 4-dimethylaminophenyl residue were prepared and subsequently quaternized by means of iodomethane. Photobactericidal activity was assessed using Propionibacterium acnes. The quaternary N,N,N -trimethyl-anilinium derivative displayed a pronounced photodynamic inactivation of the bacteria at low incubation concentrations (<100 nm) and a short incubation time (1 h) after illumination with yellow light (590 nm, 20 J cm,2), whereas the photobactericidal efficacy of the N -methyl-pyridinium derivative was negligible under identical experimental conditions. [source] Mitochondrial Responses of Normal and Injured Human Skin Fibroblasts Following Low Level Laser Irradiation,An In Vitro StudyPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Innocent L. Zungu Laser irradiation has proved to be very efficient in speeding and improving the quality of healing in pathological conditions of diverse etiologies. However, the mechanisms by which the beneficial effects are attained are not clear. Mitochondria are the primary phototargets during irradiation. The study aimed to establish if laser irradiation had an effect on hypoxic and acidotic cells. The study also aimed to use existing information regarding the possible mechanism of action (established in wounded cells) and apply these principles to acidic and hypoxic irradiated cells to determine whether laser has a stimulatory or inhibitory effect. Cell cultures were modified to simulate conditions of hypoxia (hypoxic gas mixture 95% N2 and 5% O2) and acidosis (pH 6.7) whereas the central scratch model was used to simulate a wound. Cells were irradiated with a helium,neon (632.8 nm, 3 mW cm,2) laser using 5 or 16 J cm,2 on days 1 and 4. Mitochondrial responses were measured 1 or 24 h after laser irradiation by assessing changes in mitochondrial membrane potential (MMP), cyclic AMP, intracellular Ca2+ and adenosine triphosphate (ATP) cell viability. Hypoxia and acidosis significantly reduced MMP when compared with normal nonirradiated control cells. Wounded, hypoxic and acidotic cells irradiated with 5 J cm,2 showed an increase in mitochondrial responses when compared with nonirradiated cells while 16 J cm,2 showed a significant decrease. The study confirmed that laser irradiation with 5 J cm,2 stimulated an increase in intracellular Ca2+ which resulted in an increase in MMP, ATP and cAMP, which ultimately results in photobiomodulation to restore homeostasis of injured cells. [source] The Relationship of Phthalocyanine 4 (Pc 4) Concentrations Measured Noninvasively to Outcome of Pc 4 Photodynamic Therapy in MicePHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Lihua Bai The ability to noninvasively measure photosensitizer concentration at target tissues will allow optimization of photodynamic therapy (PDT) and could improve outcome. In this study, we evaluated whether preirradiation tumor phthalocyanine 4 (Pc 4) concentrations, measured noninvasively by the optical pharmacokinetic system (OPS), correlated with tumor response to PDT. Mice bearing human breast cancer xenografts were treated with 2 mg kg,1 Pc 4 iv only, laser irradiation (150 J cm,2) only, Pc 4 followed by fractionated irradiation or Pc 4 followed by continuous irradiation. Laser irradiation treatment was initiated when the tumor to skin ratio of Pc 4 concentration reached a maximum of 2.1 at 48 h after administration. Pc 4 concentrations in tumor, as well as in Intralipid in vitro, decreased monoexponentially with laser fluence. Pc 4-PDT resulted in significant tumor regression, and tumor response was similar in the groups receiving either fractionated or continuous irradiation treatment after Pc 4. Tumor growth delay following Pc 4-PDT correlated with OPS-measured tumor Pc 4 concentrations at 24 h prior to PDT (R2 = 0.86). In excised tumors, OPS-measured Pc 4 concentrations were similar to the HPLC-measured concentrations. Thus, OPS measurements of photosensitizer concentrations can be used to assist in the scheduling of Pc 4-PDT. [source] Amelioration of Airway Stenosis in Rabbit Models by Photodynamic Therapy with Talaporfin Sodium (NPe6)PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2009Yoshinori Nakagishi It is difficult to treat patients with acquired airway stenosis, and the quality of life of such patients is therefore lowered. We have suggested the application of photodynamic therapy (PDT) as a new treatment for airway stenosis and have determined the efficacy of PDT in animal disease models using a second-generation photosensitizer with reduced photosensitivity. An airway stenosis rabbit model induced by scraping of the tracheal mucosa was administered NPe6 (5 mg kg,1), and the stenotic lesion was irradiated with 670 nm light emitted from a cylindrical diffuser tip at 60 J cm,2 under bronchoscopic monitoring. PDT using NPe6 improved airway stenosis (P = 0.043) and respiratory stridor. A significant prolongation of survival time was seen in the PDT-treated animals compared to that in the untreated animals (P = 0.025) and 44% of the treated animals achieved long-term survival (>60 days). In conclusion, PDT using NPe6 is effective for improvement in airway stenosis. [source] Effect of Two Different UVA Doses on the Rabbit Cornea and LensPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2009ejka, estmír The aim of the present paper was to examine the irradiation effect of two doses of UVA rays (365 nm) on the rabbit cornea and lens. Corneas of anesthetized adult albino rabbits were irradiated with UVA rays for 5 days (daily dose 1.01 J cm,2 in one group of rabbits and daily dose 2.02 J cm,2 in the second group of animals). The third day after the last irradiation, the rabbits were killed, and their eyes were employed for spectrophotometrical, biochemical and immunohistochemical investigations. Normal eyes served as controls. Absorption spectra of the whole corneal centers were recorded over the UV,VIS (visible) spectral range. Levels of antioxidant and prooxidant enzymes, nitric oxide synthases and nitric oxide (indirectly measured as nitrate concentration) were investigated in the cornea. Malondialdehyde, a byproduct of lipid peroxidation, was examined in the cornea and lens. The results show that the staining for endothelial nitric oxide synthase was more pronounced in corneas irradiated with the higher UVA dose. Otherwise, UVA rays at either dose did not significantly change corneal light absorption properties and did not cause statistically significant metabolic changes in the cornea or lens. In conclusion, UVA rays at the employed doses did not evoke harmful effects in the cornea or lens. [source] Effect of Low Intensity Helium,Neon (HeNe) Laser Irradiation on Experimental Paracoccidioidomycotic Wound Healing DynamicsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2009Maria Carolina Ferreira The effect of HeNe laser on the extracellular matrix deposition, chemokine expression and angiogenesis in experimental paracoccidioidomycotic lesions was investigated. At days 7, 8 and 9 postinfection the wound of each animal was treated with a 632.8 nm HeNe laser at a dose of 3 J cm,2. At day 10 postinfection, the wounds were examined by using histologic and immunohistochemical methods. Results revealed that laser-treated lesions were lesser extensive than untreated ones, and composed mainly by macrophages and lymphocytes. High IL-1, expression was shown in the untreated group whereas in laser-treated animals the expression was scarce. On the other hand, the expression of CXCL-10 was found to be reduced in untreated animals and quite intensive and well distributed in the laser-treated ones. Also, untreated lesions presented vascular endothelial growth factor (VEGF) in a small area near the center of the lesion and high immunoreactivity for hypoxia-inducible factor-1 (HIF-1), whereas laser-treated lesions expressed VEGF surrounding blood vessels and little immunoreactivity for HIF-1. Laser-treated lesions presented much more reticular fibers and collagen deposition when compared with the untreated lesion. Our results show that laser was efficient in minimizing the local effects observed in paracoccidioidomycosis and can be an efficient tool in the treatment of this infection, accelerating the healing process. [source] Monitoring ALA-induced PpIX Photodynamic Therapy in the Rat Esophagus Using Fluorescence and Reflectance SpectroscopyPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2008Bastiaan Kruijt The presence of phased protoporphyrin IX (PpIX) bleach kinetics has been shown to correlate with esophageal response to 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) in animal models. Here we confirm the existence of phased PpIX photobleaching by increasing the temporal resolution of the fluorescence measurements using the therapeutic illumination and long wavelength fluorescence detection. Furthermore fluorescence differential pathlength spectroscopy (FDPS) was incorporated to provide information on the effects of PpIX and tissue oxygenation distribution on the PpIX bleach kinetics during illumination. ALA at a dose of 200 mg kg,1 was orally administered to 15 rats, five rats served as control animals. PDT was performed at an in situ measured fluence rate of 75 mW cm,2 using a total fluence of 54 J cm,2. Forty-eight hours after PDT the esophagus was excised and histologically examined for PDT-induced damage. Fluence rate and PpIX photobleaching at 705 nm were monitored during therapeutic illumination with the same isotropic probe. A new method, FDPS, was used for superficial measurement on saturation, blood volume, scattering characteristics and PpIX fluorescence. Results showed two-phased PpIX photobleaching that was not related to a (systematic) change in esophageal oxygenation but was associated with an increase in average blood volume. PpIX fluorescence photobleaching measured using FDPS, in which fluorescence signals are only acquired from the superficial layers of the esophagus, showed lower rates of photobleaching and no distinct phases. No clear correlation between two-phased photobleaching and histologic tissue response was found. This study demonstrates the feasibility of measuring fluence rate, PpIX fluorescence and FDPS during PDT in the esophagus. We conclude that the spatial distribution of PpIX significantly influences the kinetics of photobleaching and that there is a complex interrelationship between the distribution of PpIX and the supply of oxygen to the illuminated tissue volume. [source] Fluorescence Kinetics of Protoporphyrin-IX Induced from 5-ALA Compounds in Rabbit Postballoon Injury Model for ALA-PhotoangioplastyPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Oh-Choon Kwon Protoporphyrin IX (PpIX) is one of the photodynamically active substances that are endogenously synthesized in the metabolic pathway for heme as a precursor. Aminolevulinic acid-esters are more lipophilic than conventional 5-aminolevulinic acid (ALA) and some of them are currently being approved as new drugs for photodynamic diagnosis (PDD) and photodynamic therapy (PDT). In order to investigate the pharmacokinetics of ALA and ALA-ethyl ester (ALA-ethyl) in the atheromatous plaque and normal aortic wall of rabbit postballoon injured artery, each 60 mg kg,1 of ALA or ALA-ethyl was injected intravenously followed by serial detection of PpIX fluorescence of harvested arteries at 0,48 h post-injection. Maximum PpIX build-up in the atheromatous plaque was seen at 2 h after injecting ALA. In contrast, it occurred at 9 h after injecting ALA-ethyl. In addition, the selective build-up of ALA in the atheromatous plaque compared to normal vessel wall was much higher (10 times) than that of ALA-ethyl. The time of maximum fluorescence intensity of PpIX was employed as drug-light-interval for subsequent PDT treatment of the atheromatous plaque with 50,150 J cm,1 of light dose. Significant reduction in plaque was observed without damage of the medial wall at both groups, but smooth muscle cell (SMC) was still present in the media region below the PDT-treated atheromatous plaque. In conclusion, ALA may be a more effective compound for endovascular PDT treatment of the atheromatous plaque compared with ALA-ethyl based on their pharmacokinetics, but further optimization of PDT methodology remains to remove completely residual SMC in the media for preventing potential restenosis. [source] Photochemistry and Photocytotoxicity of Alkaloids from Goldenseal (Hydrastis canadensis L.) 3: Effect on Human Lens and Retinal Pigment Epithelial CellsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Colin F. Chignell ABSTRACT The dried root or rhizome of Goldenseal (Hydrastis canadensis L.) contains several alkaloids including berberine, hydrastine, palmatine and lesser amounts of canadine and hydrastinine. Preparations derived from Goldenseal have been used to treat skin and eye ailments. Berberine, the major alkaloid in Goldenseal root powder, has been used in eye drops to treat trachoma, a disease characterized by keratoconjunctivitis. Berberine and palmatine are also present in extracts from Berberis amurensis Ruprecht (Berberidaceae) which are used to treat ocular disorders. We have previously shown that Goldenseal alkaloids are phototoxic to keratinocytes (Chem Res Toxicol. 14, 1529, 2001; ibid 19, 739, 2006) and now report their effect on human lens and retinal pigment epithelial cells. Human lens epithelial cells (HLE-B3) were severely damaged when incubated with berberine (25 ,M) and exposed to UVA (5 J cm,2). Under the same conditions, palmatine was less phototoxic and hydrastine, canadine and hydrastinine were inactive. Moderate protection against berberine phototoxicity was afforded by the antioxidants ascorbate (2 mM) and N -acetylcysteine (5 mM). When exposed to UVA (5 J cm,2) both berberine (10 ,M) and palmatine (10 ,M) caused mild DNA damage as determined by the alkaline comet assay which measures single strand breaks. Berberine and palmatine are the only Goldenseal alkaloids with appreciable absorption above 400 nm. Because light at wavelengths below 400 nm is cut off by the anterior portion of the adult human eye only berberine and palmatine were tested for phototoxicity to human retinal pigment epithelial (hRPE) cells. Although berberine did damage hRPE cells when irradiated with visible light (, > 400 nm) approximately 10 times higher concentrations were required to produce the same amount of damage as seen in lens cells. Palmatine was not phototoxic to hRPE cells. Neither berberine nor palmatine photodamaged DNA in hRPE. Infusions of Goldenseal are estimated to contain ,1 mM berberine, while in tinctures the alkaloid concentration may be more than 10 times higher. Our findings show that eyewashes and lotions derived from Goldenseal or containing berberine must be used with caution when the eyes are exposed to bright sunlight but that oral preparations are not likely to cause ocular phototoxicity. [source] Detection of Modified Tyrosines as an Inflammation Marker in a Photo-aged Skin ModelPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2007Yukiko Ishitsuka Reactive nitrogen species, produced during the process of inflammation induced by various factors including UV radiation, modify amino acids in crucial proteins. It is assumed that skin tissue is more likely to be modified, as it is located at the outer layer of a body that is exposed to UV radiation on a daily basis. To investigate the influence of the modified tyrosine on UV-exposed skin, we detected the nitrotyrosine or halogenated tyrosine and dityrosine in photo-aged model mice. The back skin of mice was exposed to a dose of 10 J cm,2 day,1 every day for 15 weeks. Samples exhibiting typical symptoms of photo aging were provided to the immunofluorescence study. The quantification of modified proteins was accomplished through a chemical analytical method known as HPLC-tandem mass spectrometry. Analysis of the irradiated skin samples showed that all modified tyrosine except nitrotyrosine demonstrated statistically significant increases. The molecular weights of major modified proteins, confirmed as 25,50 kDa, were measured using Western blot analysis with an anti-nitrotyrosine antibody. Furthermore, the immunofluorescence study verified that the localization of myeloperoxidase conformed to that of nitrotyrosine. This result suggests that the modified tyrosine was produced during the process of inflammation by UV irradiation. In this study, we used a low dose of UV irradiation to which we are exposed in daily life. Our results suggest that UV exposure in daily life may induce the production of modified tyrosines and skin aging. [source] Phototoxicity in Human Retinal Pigment Epithelial Cells Promoted by Hypericin, a Component of St. John's Wort,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2007Albert R. Wielgus ABSTRACT St. John's wort (SJW), an over-the-counter antidepressant, contains hypericin, which absorbs light in the UV and visible ranges. In vivo studies have determined that hypericin is phototoxic to skin and our previous in vitro studies with lens tissues have determined that it is potentially phototoxic to the human lens. To determine if hypericin might also be phototoxic to the human retina, we exposed human retinal pigment epithelial (hRPE) cells to 10,7 to 10,5 M hypericin. Fluorescence emission detected from the cells (,ex = 488 nm; ,em = 505 nm) confirmed hypericin uptake by human RPE. Neither hypericin exposure alone nor visible light exposure alone reduced cell viability. However when irradiated with 0.7 J cm,2 of visible light (, > 400 nm) there was loss of cell viability as measured by MTS and lactate dehydrogenase assays. The presence of hypericin in irradiated hRPE cells significantly changed the redox equilibrium of glutathione and a decrease in the activity of glutathione reductase. Increased lipid peroxidation as measured by the thiobarbituric acid reactive substances assay correlated to hypericin concentration in hRPE cells and visible light radiation. Thus, ingested SJW is potentially phototoxic to the retina and could contribute to retinal or early macular degeneration. [source] Effects of Combined Photodynamic Therapy and Ionizing Radiationon Human Glioma Spheroids,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2002Steen J. Madsen ABSTRACT The effects of combined photodynamic therapy (PDT) and ionizing radiation are studied in a human glioma spheroid model. The degree of interaction between the two modalities depends in a complex manner on factors such as PDT irradiation fluence, fluence rate and dose of ionizing radiation. It is shown that gamma radiation and PDT interact in a synergistic manner only if both light fluence and gamma radiation dose exceed approximately 25 J cm,2 and 8 Gy, respectively. Synergistic interactions are observed only for the lower fluence rate (25 mW cm,2) investigated. The degree of interaction appears to be independent of both sequence and the PDT or ionizing radiation time intervals investigated (1 and 24 h). Terminal deoxynucleotidyl transferase,mediated deoxyuridine triphosphate nick-end labeling assays show that low-fluence rate PDT is very efficient at inducing apoptotic cell death, whereas neither high-fluence rate PDT nor ionizing radiation produces significant apoptosis. Although the mechanisms remain to be elucidated, the data imply that the observed synergism is likely not due to gamma-induced cell cycle arrest or to PDT-induced inhibition of DNA repair. [source] Effect of ultraviolet (UV) A, UVB or ionizing radiation on the cell cycle of human melanoma cellsBRITISH JOURNAL OF DERMATOLOGY, Issue 5 2007M. Placzek Summary Background, One important component of the cellular response to irradiation is the activation of cell cycle checkpoints. It is known that both ultraviolet (UV) radiation and ionizing radiation (IR) can activate checkpoints at transitions from G1 to S phase, from G2 phase to mitosis and during DNA replication. Objectives, To evaluate the effects of irradiation with different wavelengths on cell cycle alterations. Methods, p53-deficient IPC-298 melanoma cells were irradiated with 10 J cm,2 UVA, 40 mJ cm,2 UVB, or with 7·5 Gy IR. Cell cycle effects were then determined by DNA/5-bromodeoxyuridine dual-parameter flow cytometry. Results, IPC-298 cells irradiated in G1 with UVA were not arrested at the G1/S transition, but at the G2/M transition. Despite p53 deficiency, the cells showed a G1 arrest after UVB exposure. Furthermore, IR did not affect G1 or S phase, but induced G2 phase arrest. Hence, the effects of UVA, but not of UVB, on the cell cycle in p53-deficient melanoma cells are comparable with those of IR. Conclusions, UVA and IR induce radical-mediated strand breaks and DNA lesions, and UVB essentially induces thymine dimers that lead to excision repair-related strand breaks. Different cell cycle effects may be a consequence of different types of DNA damage. The results showed that UVB-irradiated p53-deficient cells are arrested in G1. Irradiation with the solar radiation component UVB can therefore result in a beneficial retardation of tumour promotion in human skin carrying p53-mutated cell clones. [source] In vitro and in vivo comparison of two different light sources for topical photodynamic therapyBRITISH JOURNAL OF DERMATOLOGY, Issue 4 2006P. Babilas Summary Background, Photodynamic therapy (PDT) with 5-aminolaevulinic acid (ALA) is an effective and safe treatment option for the treatment of actinic keratosis (AK). Incoherent lamps are often used, matching the absorption maxima of ALA. Objectives, A comparative trial was performed to evaluate the efficacy of recently developed light-emitting diodes (LEDs). Methods, Human epidermal keratinocytes were incubated for 24 h with ALA (100, 200, 300, 400 or 500 ,mol L,1) and irradiated consecutively using either an incoherent halogen lamp (,em = 580,750 nm; 24 J cm,2; 40 mW cm,2) or an LED system (,em = 633 ± 3 nm; 3, 6, 12 or 24 J cm,2; 40 mW cm,2). Topical ALA-PDT was performed on 40 patients with AK (n = 584) in a symmetrical distribution suitable for two-sided comparison. After incubation with ALA (20% in cream base) irradiation was performed with the incoherent lamp (100 J cm,2; 160 mW cm,2) on one side and the LED system (40 J cm,2; 80 mW cm,2) on the opposite side followed by re-evaluation up to 6 months. Results, No significant differences between the LED system (3, 6, 12 or 24 J cm,2) and the incoherent light source (24 J cm,2) regarding cytotoxicity was found in vitro. The complete remission rate yielded in the in vivo investigation was also not significantly different at 6 weeks (P = 0·95), 3 months (P = 0·75) and 6 months (P = 0·61) following therapy. Six weeks following therapy complete remission rates of 84·3% (LED system) and 82·8% (incoherent lamp) were achieved. There was also no significant difference between both light sources regarding pain during light treatment (P = 0·67), patient satisfaction (P = 1·0) or cosmesis (P = 1·0) following therapy. Conclusions, These results show the efficacy of an LED system for ALA-PDT both in vitro and in vivo. ALA-PDT with the LED system showed a noninferiority regarding the clinical outcome in the treatment of AK compared with the incoherent lamp. [source] Percutaneous absorption of the sunscreen benzophenone-3 after repeated whole-body applications, with and without ultraviolet irradiationBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2006H. Gonzalez Summary Background, Benzophenone-3 (BZ-3; 2-hydroxy-4-methoxybenzophenone, oxybenzone) is commonly used to absorb ultraviolet (UV) radiation. BZ-3 penetrates the skin and can be found in the urine. The amount varies between 0·4% and 2%. This seems to be the main metabolic pathway in rats. Objectives, To investigate the total amount of BZ-3 excreted in the urine after repeated topical whole-body applications of a sunscreen and to see if UV radiation has any effect on the amount excreted. Methods, Twenty-five volunteers applied a commercially available sunscreen containing 4% BZ-3 morning and night for 5 days. Their urine was measured during those 5 days and during a further 5 days after the last application. They were divided into groups A (unirradiated) and B. Group B received UV radiation according to skin type: UVA between 400 and 707 J cm,2, and UVB between 0·46 and 2·0 J cm,2. BZ-3 in urine was analysed with a high-performance liquid chromatography method. Results, The volunteers excreted 1·2,8·7% (mean 3·7%) of the total amount of BZ-3 applied. There was no significant difference between the two groups (P < 0·99, t -test). Conclusions, We show that a large amount of BZ-3 is absorbed. BZ-3 is accumulated in the body as the volunteers excreted BZ-3 5 days after the last application. [source] A comparative study of a 595-nm with a 585-nm pulsed dye laser in refractory port wine stainsBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2005A. Yung Summary Background, The pulsed dye laser (PDL) is the treatment of choice for port wine stains (PWS); however, some patients' PWS become refractory to further treatments. Technological advances have enabled new machines with the advent of surface cooling devices to deliver longer wavelengths and higher fluence more safely. These advances have the potential to achieve improved response rates in refractory PWS. There are few studies comparing the efficacy of standard PDL treatments for refractory PWS with the wider choice of treatment variables available from newer PDL machines. Objectives, To determine if there is any advantage of using a longer wavelength (595 nm) and pulse widths (1·5 ms, 6 ms and 20 ms) over conventional PDL settings (wavelength 585 nm, pulse width 1·5 ms) in refractory PWS. Methods, Eighteen consecutive consenting patients with Fitzpatrick skin types 1,4 with a mean age 35 years (range 17,59 years) with refractory PWS were treated routinely with three separate test areas using 595-nm PDL (using three different pulse width settings of 1·5 ms, 6 ms and 20 ms), compared with test areas treated with 585-nm PDL (pulse width 1·5 ms). All test areas were treated with an identical fluence (15 J cm,2), spot size (7 mm) and cooling setting (dynamic cooling 60 ms, delay 60 ms). Results, We found a statistically significant advantage of 595-nm PDL (pulse width 1·5 ms) over 595-nm PDL (pulse width 6 ms) (P < 0·05) in the treatment of refractory PWS; however, we found no significant advantage using longer pulse widths of 20 ms compared with 1·5 ms with the 595-nm PDL. There was no statistically significant advantage in using a 595-nm PDL over a 585-nm PDL using identical pulse widths of 1·5 ms, spot size, fluence and cryogen cooling settings; however, the number of directly comparable test areas was smaller. Some individual patients in our study obtained a better response with certain 595-nm PDL settings (pulse width 1·5 ms and 6 ms) compared with 585-nm PDL (pulse width 1·5 ms). Conclusions, Our experience of high fluence PDL in the treatment of refractory PWS suggests patients treated with 585 nm (pulse width 1·5 ms) improve to a similar degree as patients treated with 595-nm PDL (pulse width 1·5 ms). However, the use of the 595-nm PDL with longer pulse widths yields no extra advantage. For those patients who have failed to improve with high-fluence 585-nm PDL (pulse width 1·5 ms), test areas using 595-nm PDL (pulse width 1·5 ms and 6 ms) should be undertaken to ascertain if individual patients may benefit from the longer pulse width 595-nm PDL. [source] Topical aminolaevulinic acid-based photodynamic therapy as a treatment option for psoriasis?BRITISH JOURNAL OF DERMATOLOGY, Issue 2 2005Results of a randomized, observer-blinded study Summary Background, Topical aminolaevulinic acid-based photodynamic therapy (ALA-PDT) has recently been tried in small open studies for several inflammatory dermatoses including psoriasis. Objectives, The purpose of this randomized, within patient comparison study was to investigate whether topical ALA-based PDT using a range of light doses can induce a satisfactory response in localized psoriasis. Patients and methods, Twenty-nine patients with chronic plaque type psoriasis were enrolled in the study. After keratolytic pretreatment three psoriatic plaques in each patient were randomly allocated to PDT with 1% ALA and a light dose of 5 J cm,2, 10 J cm,2 or 20 J cm,2, respectively. Treatment was performed twice weekly until complete clearance or for a maximum of 12 irradiations. As a measure of clinical response the psoriasis severity index (PSI) of the three target plaques was assessed separately by an observer blinded to the treatment at baseline, before each PDT treatment and 3,4 days after the last irradiation. Results, Eight patients withdrew prematurely from the study. Keratolytic pretreatment alone reduced the baseline PSI in all three dose groups by about 25%. Subsequent PDT with 20 J cm,2 resulted in a final reduction of PSI by 59%, PDT with the lower doses of 10 J cm,2 and 5 J cm,2 decreased the baseline PSI by 46% and 49%, respectively. The difference in clinical efficacy between 20 J cm,2 and 10 J cm,2 or 5 J cm,2 was statistically significant (P = 0·003; P = 0·02), whereas no difference was found between 10 J cm,2 and 5 J cm,2 (P = 0·4). All patients reported some degree of PDT-induced stinging or burning during irradiation. Conclusions, The unsatisfactory clinical response and frequent occurrence of pain during and after irradiation renders topical ALA-based PDT an inadequate treatment option for psoriasis. [source] Photodynamic therapy of actinic keratosis at varying fluence rates: assessment of photobleaching, pain and primary clinical outcomeBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2004M.B. Ericson Summary Background, Although photodynamic therapy (PDT) is becoming an important treatment method for skin lesions such as actinic keratosis (AK) and superficial basal cell carcinoma, there are still discussions about which fluence rate and light dose are preferable. Recent studies in rodents have shown that a low fluence rate is preferable due to depletion of oxygen at high fluence rates. However, these results have not yet been verified in humans. Objectives, The objective was to investigate the impact of fluence rate and spectral range on primary treatment outcome and bleaching rate in AK using aminolaevulinic acid PDT. In addition, the pain experienced by the patients has been monitored during treatment. Patients/methods, Thirty-seven patients (mean age 71 years) with AK located on the head, neck and upper chest were treated with PDT, randomly allocated to four groups: two groups with narrow filter (580,650 nm) and fluence rates of 30 or 45 mW cm,2, and two groups with broad filter (580,690 nm) and fluence rates of 50 or 75 mW cm,2. The total cumulative light dose was 100 J cm,2 in all treatments. Photobleaching was monitored by fluorescence imaging, and pain experienced by the patients was registered by using a visual analogue scale graded from 0 (no pain) to 10 (unbearable pain). The primary treatment outcome was evaluated at a follow-up visit after 7 weeks. Results, Our data showed a significant correlation between fluence rate and initial treatment outcome, where lower fluence rate resulted in favourable treatment response. Moreover, the photobleaching dose (1/e) was found to be related to fluence rate, ranging from 4·5 ± 1·0 J cm,2 at 30 mW cm,2, to 7·3 ± 0·7 J cm,2 at 75 mW cm,2, indicating higher oxygen levels in tissue at lower fluence rates. After a cumulative light dose of 40 J cm,2 no further photobleaching took place, implying that higher doses are excessive. No significant difference in pain experienced by the patients during PDT was observed in varying the fluence rate from 30 to 75 mW cm,2. However, the pain was found to be most intense up to a cumulative light dose of 20 J cm,2. Conclusions, Our results imply that the photobleaching rate and primary treatment outcome are dependent on fluence rate, and that a low fluence rate (30 mW cm,2) seems preferable when performing PDT of AK using noncoherent light sources. [source] Topical aminolaevulinic acid-photodynamic therapy for the treatment of acne vulgaris: a study of clinical efficacy and mechanism of actionBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2004B. Pollock Summary Background, ,Acne affects 83,95% of 16-year-olds of both sexes, and many seek help from a clinician. Emerging problems with conventional acne treatments, specifically antibiotic resistance of Propionibacterium acnes and fears over the safety and tolerance of oral isotretinoin, create a demand for novel treatment modalities in acne. Objectives, To study the efficacy of aminolaevulinic acid-photodynamic therapy (ALA-PDT) in the treatment of acne and to identify the mode of action, looking specifically at the effects on surface numbers of P. acnes and on sebum excretion. Methods, ,Ten patients (nine men and one woman, age range 16,40 years) with mild to moderate acne on their backs were recruited. Each patient's back was marked with four 30-cm2 areas of equal acne severity. Each site was then randomly allocated to either ALA-PDT treatment, light alone, ALA alone or an untreated control site. At baseline, numbers of inflammatory and noninflammatory acne lesions were counted, sebum excretion measured by Sebutapes (CuDerm, Dallas, TX, U.S.A.) and surface P. acnes swabs performed. ALA cream (20% in Unguentum Merck) was applied under occlusion to the ALA-PDT and ALA alone sites for 3 h. Red light from a diode laser was then delivered to the ALA-PDT and light alone sites (635 nm, 25 mW cm,2, 15 J cm,2). Each patient was treated weekly for 3 weeks. At each visit acne lesion counts were performed and 3 weeks following the last treatment sebum excretion rates and P. acnes swabs were repeated. Results, There was a statistically significant reduction in inflammatory acne lesion counts from baseline after the second treatment at the ALA-PDT site but not at any of the other sites. No statistically significant reduction in P. acnes numbers or sebum excretion was demonstrated at any sites including the ALA-PDT site. Conclusions, ALA-PDT is capable of clinically improving acne. An alternative mode of action for ALA-PDT other than direct damage to sebaceous glands or photodynamic killing of P. acnes is suggested from the results of this study. [source] Plasma levels of opioid peptides after sunbed exposuresBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2002T. Gambichler Summary Background Previous studies have indicated that solar and artificial ultraviolet (UV) radiation have a positive influence on psychological variables such as mood and emotional state. Circulating opioid peptides have been suggested as being important in this effect. Objectives To investigate in a controlled trial the influence of UVA radiation on opioid peptide levels. Methods We determined plasma levels of ,-endorphin immunoreactive material (IRM) and met-enkephalin in UV-exposed ( n = 35) and non-exposed ( n = 9) healthy volunteers. On the first day of the study, blood samples were taken from the volunteers (time A). UVA irradiation was subsequently administered with an air-conditioned tanning device. During the UV exposures the volunteers wore opaque goggles. Twenty minutes after UV exposure, blood samples were collected again (time B). Within the following 3 weeks the volunteers had a series of five UV exposures. On the last day of the study (24 h after the sixth UV exposure) blood samples were collected (time C). The cumulative UVA doses were 96 J cm ,2 for skin type II and 126 J cm ,2 for skin type III. The controls had no UV exposures. Plasma ,-endorphin IRM and met-enkephalin levels were determined using radioimmunoassays. Results At all times of blood collection (A, B, C), there were no significant differences in plasma levels of ,-endorphin IRM and met-enkephalin between UV-exposed and non-exposed volunteers ( P > 0·05). Conclusions UVA irradiation does not significantly elevate plasma levels of ,-endorphin IRM and met-enkephalin. Therefore we suggest that psychological benefits claimed to occur after UV exposure are unlikely to be mediated by the types of circulating opioid peptides measured in this study. [source] | |||||||||||||