The Effect of Actinoquinol with Hyaluronic Acid in Eye Drops on the Optical Properties and Oxidative Damage of the Rabbit Cornea Irradiated with UVB Rays

Irradiation of the cornea with UVB rays leads to its oxidative damage, swelling and increased light absorption. We investigated changes in the corneal optics (evaluated by changes of corneal hydration and light absorption) and microscopical disturbances of corneas irradiated with UVB rays as influenced by eye drops containing actinoquinol with hyaluronic acid. Rabbit corneas were irradiated with a daily dose of 0.5 or 1.01 J cm⁻² of UVB rays (312 nm) for 4 days. During irradiation, the eye drops were applied on the right eye and buffered saline (or hyaluronic acid) on the left eye. On day 5 the rabbits were sacrificed and the corneas examined spectrophotometrically for light absorption. The corneal thickness (hydration) was measured using a pachymeter. Corneas of some other rabbits were examined immunohistochemically. After buffered saline treatment UVB rays evoked changes in the corneal optics and induced oxidative damage of the corneas. After actinoquinol-hyaluronic acid application, these changes were diminished. Hyaluronic acid alone was less effective. In conclusion, actinoquinol-hyaluronic acid eye drops decreased changes in corneal optics and suppressed oxidative damage in the UVB-irradiated cornea. However, the effective corneal protection by these eye drops was limited to the lower UVB dose.     

Effect of Two Different UVA Doses on the Rabbit Cornea and Lens

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.     

Light absorption properties of the rabbit cornea repeatedly irradiated with UVB rays

Under normal conditions, the cornea absorbs the majority of UVB (ultraviolet B, 280-320 nm) rays, which is very important for the protection of the inner eye against their damaging effect. Our previous studies have shown that repeated irradiation of the rabbit cornea with UVB rays for 5 days (daily dose of 1.01 J cm(- 2)) caused photokeratitis accompanied by swelling (hydration) of the corneal stroma, thinning of the corneal epithelium and decrease in antioxidants. The purpose of this study was to examine the light absorption properties of such damaged rabbit cornea. Results of both spectrophotometry of the whole corneal buttons and corneal tissue dissolved in sodium hydroxide show that because of above mentioned disturbances, UVB-irradiated cornea absorbs more light throughout the whole measurable UV-VIS spectral range than the normal cornea. Increased corneal thickness (result of hydration), changes of corneal transparency (the cornea becomes grayish) and some increase in protein content all contribute to the increased light absorption of UVB irradiated corneas. We suggest that the UVB-irradiated cornea, although damaged and nearly without antioxidants, might actually through its higher UV absorbance protect the inner eye against further damage from UVB rays.     

The Injury and Cumulative Effects on Human Skin by UV Exposure from Artificial Fluorescence Emission

The injury and cumulative effects of UV emission from fluorescence lamp were studied. UV intensity from fluorescence lamp was measured, and human skin samples (hips, 10 volunteers) were exposed to low‐dose UV irradiation (three times per week for 13 consecutive weeks). Three groups were examined: control group without UV radiation; low‐dose group with a cumulative dose of 50 J cm^?2 which was equivalent to irradiation of the face during indoor work for 1.5 years; and high‐dose group with 1000 J cm^?2 cumulative dose equivalent to irradiation of the face during outdoor activities for 1 year. Specific indicators were measured before and after UVA irradiation. The findings showed that extending the low‐dose UVA exposure decreased the skin moisture content and increased the transepidermal water loss as well as induced skin color changes (decreased L* value, increased M index). Furthermore, irradiated skin showed an increased thickness of cuticle and epidermis, skin edema, light color and unclear staining collagen fibers in the dermis, and elastic fiber fragmentation. In addition, MMP‐1, p53 and SIRT1 expression was also increased. Long‐term exposure of low‐dose UVA radiation enhanced skin photoaging. The safety of the fluorescent lamp needs our attention.     

Red Light Interferes in UVA‐Induced Photoaging of Human Skin Fibroblast Cells

The possible regulation mechanism of red light was determined to discover how to retard UVA‐induced skin photoaging. Human skin fibroblasts were cultured and irradiated with different doses of UVA, thus creating a photoaging model. Fibroblasts were also exposed to a subtoxic dose of UVA combined with a red light‐emitting diode (LED) for five continuous days. Three groups were examined: control, UVA and UVA plus red light. Cumulative exposure doses of UVA were 25 J cm^?2, and the total doses of red light were 0.18 J cm^?2. Various indicators were measured before and after irradiation, including cell morphology, viability, β‐galactosidase staining, apoptosis, cycle phase, the length of telomeres and the protein levels of photoaging‐related genes. Red light irradiation retarded the cumulative low‐dose UVA irradiation‐induced skin photoaging, decreased the expression of senescence‐associated β‐galactosidase, upregulated SIRT1 expression, decreased matrix metalloproteinase MMP‐1 and the acetylation of p53 expression, reduced the horizon of cell apoptosis and enhanced cell viability. Furthermore, the telomeres in UVA‐treated cells were shortened compared to those of cells in the red light groups. These results suggest that red light plays a key role in the antiphotoaging of human skin fibroblasts by acting on different signaling transduction pathways.     

Histopathological Analysis of UVB and IR Interaction in Rat Skin

To determine the chronic skin effects caused by the interaction of infrared and ultraviolet B radiations, male Rattus norvegicus (Wistar) (2 months old) were exposed for 15 days to infrared radiation (600–1500 nm, with a peak at 1000 nm, n = 12) for 30 min (1080 J cm^?2) (IRo); to ultraviolet B radiation (peak emission at 313 nm, n = 9) for 90 min (55.08 J cm^?2) (UVB); to infrared radiation followed after 90 min by ultraviolet B (n = 6) (IRUVB) and to ultraviolet B followed after 90 min by infrared radiation (n = 9) (UVBIR). Skin samples were collected and histopathological analysis showed the presence of acanthosis, parakeratotic and orthokeratotic hyperkeratosis, intraepidermal pustules, keratin pearls, detachment of epidermis, collagen necrosis, inflammatory infiltrate, vasodilation, basal cell vacuolization and superficial dermis degeneration both in UVB and UVBIR treatments. IRUVB animals showed the same characteristics as above except for parakeratotic hyperkeratosis, keratin pearls and superficial dermis degeneration. To conclude, infrared radiation exposure after ultraviolet B irradiation increases skin damage without protecting the tissue, while infrared radiation exposure before ultraviolet B irradiation showed a protective effect against ultraviolet skin damage.     

Biomodulation of Inflammatory Cytokines Related to Oral Mucositis by Low‐Level Laser Therapy

This study evaluated the effects of LLLT on the expression of inflammatory cytokines related to the development of oral mucositis by gingival fibroblasts. Primary gingival fibroblasts were seeded on 24‐well plates (10⁵ cells/well) for 24 h. Fresh serum‐free culture medium (DMEM) was then added, and cells were placed in contact with LPS (Escherichia coli, 1 μg mL^?1), followed by LLLT irradiation (LaserTABLE—InGaAsP diode prototype—780 nm, 25 mW) delivering 0, 0.5, 1.5 or 3 J cm^?². Cells without contact with LPS were also irradiated with the same energy densities. Gene expression of TNF‐α, IL‐1β, IL‐6 and IL‐8 was evaluated by Real‐Time PCR, and protein synthesis of these cytokines was determined by enzyme‐linked immunosorbent (ELISA) assay. Data were statistically analyzed by the Kruskal–Wallis test, complemented by the Mann–Whitney test (P < 0.05). LPS treatment increased the gene expression and protein synthesis of TNF‐α, IL‐6 and IL‐8, while the expression of IL‐1β was not affected. For LPS‐treated groups, LLLT promoted significant decreases in the expression of TNF‐α, IL‐6, and IL‐8 at 1.5 J cm^?2 and 3 J cm^?2. These results demonstrate that LLLT promoted a beneficial biomodulatory effect on the expression of inflammatory cytokines related to oral mucositis by human gingival fibroblasts.     

Phototherapeutic Effect of Low‐Level Laser on Thyroid Gland of Gamma‐Irradiated Rats

One inescapable feature of life on the earth is exposure to ionizing radiation. The thyroid gland is one of the most sensitive organs to gamma‐radiation and endocrine disrupters. Low‐level laser therapy (LLLT) has been used to stimulate tissue repair, and reduce inflammation. The aim of this study was to gauge the value of using Helium–Neon laser to repair the damaged tissues of thyroid gland after gamma‐irradiation. Albino rats were used in this study (144 rats), divided into control, gamma, laser, and gamma plus laser‐irradiated groups, each group was divided into six subgroups according to time of treatment (total six sessions). Rats were irradiated once with gamma radiation (6 Gy), and an external dose of laser (Wavelength 632.8 nm, 12 mW, CW, Illuminated area 5.73 cm², 2.1 mW cm^?2, 120 s, 1.4 J, 0.252 J cm^?2) twice weekly localized on thyroid region of the neck, for a total of six sessions. Animals were sacrificed after each session. Analysis included thyroid function, oxidative stress markers, liver function and blood picture. Results revealed improvement in thyroid function, liver function and antioxidant levels, and the blood cells count after LLLT.     

Artocarpin‐enriched (Artocarpus altilis) Heartwood Extract Provides Protection Against UVB‐induced Mechanical Damage in Dermal Fibroblasts

This study aimed to evaluate the protective effect of artocarpin‐enriched (Artocarpus altilis) heartwood extract on the mechanical properties of UVB‐irradiated fibroblasts. Human skin fibroblasts were pretreated with 50 μg/mL^?1 extract and later irradiated with UVB (200 mJ/cm^?2). They were then cultured within three‐dimensional of free‐floating and tense collagen lattices. The pretreatment of fibroblasts with the extract prior to UVB radiation showed cells protection against UVB‐induced suppression of α‐SMA expression, fibroblast migration and contraction. These results reveal that the extract prevents mechanical damages induced by UVB irradiation in fibroblast‐embedded collagen lattices, and therefore, has a potential as a natural photo‐protectant.     

Reduced Levels of Tissue Inhibitors of Metalloproteinases in UVB‐Irradiated Corneal Epithelium

Tissue inhibitors of metalloproteinases (TIMPs) are the major endogenous regulators of metalloproteinase activity in tissues. TIMPs are able to inhibit activity of all known matrix metalloproteinases (MMPs) and thus participate in controlling extracellular matrix synthesis and degradation. We showed previously elevated expressions of MMPs in the rabbit corneal epithelium upon UVB exposure and suggested that these enzymes might be involved in corneal destruction caused by excessive proteolysis. The aim of this study was to investigate TIMPs in the corneal epithelium after UV irradiation using immunohistochemical and biochemical methods. We found that as compared to control rabbit corneas where relatively high levels of TIMPs were present in the epithelium, repeated irradiation of the cornea with UVB rays (not with UVA rays of similar doses) significantly decreased TIMPs in corneal epithelial cells. The results of this study point to the suggestion that the decrease in TIMPs in the corneal epithelium after UVB irradiation contributes to increased proteolytic activity of MMPs in UVB‐irradiated corneal epithelium found previously.     

Monte Carlo Model of Stricture Formation in Photodynamic Therapy of Normal Pig Esophagus

Photodynamic therapy (PDT) is FDA-approved for use in patients with Barrett's esophagus using porfimer sodium (2 mg per kg) and a recommended light dose of 130 J cm⁻¹ for high grade dysplasia. Despite uniform drug and light doses, the clinical outcome of PDT is variable. A significant number of PDT cases result in esophageal strictures, a side effect related to excessive energy absorption. The purpose of this project was to model esophageal stricture formation with a Monte Carlo simulation. An original multilayer Monte Carlo computer simulation was developed for esophageal PDT. Optical absorption and scattering coefficients were derived for mucosal and muscle layers of normal porcine esophagus. Porfimer sodium was added to each layer by increasing the absorption coefficient by the appropriate amount. A threshold-absorbed light dose was assumed to be required for stricture formation and ablation. The simulation predicted irreversible damage to the mucosa with a 160 J cm⁻¹ light dose and damage to the muscle layer with an additional 160 J cm⁻¹ light dose for a tissue porfimer sodium content of 3.5 mg kg⁻¹. The simulation accurately modeled photodynamic stricture formation in normal pig in vivo esophageal tissue. This preliminary work suggests that the absorbed light threshold for stricture formation may be between 2 and 4 J per gram of tissue.     

Light‐mediated DNA Repair Prevents UVB‐induced Cell Cycle Arrest in Embryos of the Crustacean Macrobrachium olfersi

High levels of ultraviolet‐B (UVB) radiation can negatively affect aquatic animals. Macrobrachium olfersi is a prawn that lives in clear freshwaters and during the breeding season, females carry eggs in an external brood pouch. Therefore, we hypothesize that eggs are also exposed to environmental UVB radiation. The aim of this study was to investigate whether UVB radiation induces DNA damage and compromises cell cycle in embryos of M. olfersi. In laboratory, UVB irradiance (310 mW. cm^?2) that embryos receive in the natural environment was simulated. After irradiation, embryos were kept under different light conditions in order to recognize the presence of cell repair. UVB radiation induces DNA damage, specifically thymine dimers. After 48 h of UVB exposure, a significant decrease in the level of these dimers was observed in embryos kept under visible light while it remained constant in the dark. Moreover, under visible light and darkness, a decrease in proliferation was observed after 48 h of irradiation. An increase in PCNA expression and decrease in p53 expression were observed after, respectively, 1 and 48 h of exposure. Our results showed that UVB radiation disturbs the cell cycle and induces DNA damage in M. olfersi embryos. However, under visible light these embryos showed successful DNA repair.     

UVA and UVB‐Induced 8‐Methoxypsoralen Photoadducts and a Novel Method for their Detection by Surface‐Enhanced Laser Desorption Ionization Time‐of‐Flight Mass Spectrometry (SELDI‐TOF MS)

UVA‐activated psoralens are used to treat hyperproliferative skin conditions due to their ability to form DNA photoadducts, which impair cellular processes and may lead to cell death. Although UVA (320–400 nm) is more commonly used clinically, studies have shown that UVB (280–320 nm) activation of psoralen can also be effective. However, there has been no characterization of UVB‐induced adduct formation in DNA alone. As psoralen derivatives have a greater extinction coefficient in the UVB region (11 800 cm^?1 M^?1 at 300 nm) compared with the UVA region (2016 cm^?1 M^?1 at 365 nm), a greater extent of adduct formation is expected. SELDI‐TOF, a proteomic technique that combines chromatography with mass spectrometry, was used to detect photoadduct formation in an alternating A–T oligonucleotide. 8‐Methoxypsoralen (8‐MOP) and DNA solutions were irradiated with either UVA or UVB. An adduct peak was obtained with SELDI‐TOF. For UVB‐activated 8‐MOP, the extent of adducts was three times greater than for UVA. HPLC ESI‐MS analysis showed that UVB irradiation yielded high levels of 3,4‐monoadducts (78% of total adducts). UVA was more effective than UVB at conversion of 4′,5′‐monoadducts to crosslinks (17% vs 4%, respectively). This report presents a method for comparing DNA binding efficiencies of interstrand crosslink inducing agents.     

Photodynamic Inactivation of Bacterial and Yeast Biofilms With a Cationic Porphyrin

The efficiency of 5,10,15,20‐tetrakis(1‐methylpyridinium‐4‐yl)porphyrin tetra‐iodide (Tetra‐Py⁺‐Me) in the photodynamic inactivation of single‐species biofilms of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans and mixed biofilms of S. aureus and C. albicans was evaluated. The effect on the extracellular matrix of P. aeruginosa was also assessed. Irradiation with white light up to an energy dose of 64.8 J cm^?2 in the presence of 20 μm of Tetra‐Py⁺‐Me caused significant inactivation in all single‐species biofilms (3–6 log reductions), although the susceptibility was attenuated in relation to planktonic cells. In mixed biofilms, the inactivation of S. aureus was as efficient as in single‐species biofilms but the susceptibility of C. albicans decreased. In P. aeruginosa biofilms, a reduction of 81% in the polysaccharide content of the matrix was observed after treatment with a 20 μm PS concentration and a total light dose of 64.8 J cm^?2. The results show that the Tetra‐Py⁺‐Me causes significant inactivation of the microorganisms, either in biofilms or in the planktonic form, and demonstrate that polysaccharides of the biofilm matrix may be a primary target of photodynamic damage.     

Enhancement of the Efficacy of Photodynamic Inactivation of Candida albicans with the Use of Biogenic Gold Nanoparticles

This study reports on successful photodynamic inactivation of planktonic and biofilm cells of Candida albicans using Rose Bengal (RB) in combination with biogenic gold nanoparticles synthesized by the cell‐free filtrate of Penicillium funiculosum BL1 strain. Monodispersed colloidal gold nanoparticles coated with proteins were characterized by a number of techniques including SEM–EDS, TEM, UV–Vis absorption and fluorescence spectroscopy, as well as Fourier transform infrared spectroscopy to be 24 ± 3 nm spheres. A Xe lamp (output power of 20mW, delivering intensity of 53 mW cm^?2) was used as a light source to study the effects of RB alone, the gold nanoparticles alone and the RB‐gold nanoparticle mixture on the viability of C. albicans cells. The most effective reduction in the number of planktonic cells was found after 30 min of Xe lamp light irradiation (95.4 J cm^?2) and was 4.89 log₁₀ that is 99.99% kill for the mixture of RB with gold nanoparticles compared with 2.19 log₁₀ or 99.37% for RB alone. The biofilm cells were more resistant to photodynamic inactivation, and the highest effective reduction in the number of cells was found after 30 min of irradiation in the presence of the RB–gold nanoparticles mixture and was 1.53 log₁₀, that is 97.04% kill compared with 0.6 log₁₀ or 74.73% for RB. The probable mechanism of enhancement of RB‐mediated photodynamic fungicidal efficacy against C. albicans in the presence of biogenic gold nanoparticles is discussed leading to the conclusion that this process may have a multifaceted character.     

Efficacy of Low‐Dose Ultraviolet A‐1 Phototherapy for Parapsoriasis/Early‐Stage Mycosis Fungoides

Mycosis fungoides (MF) and parapsoriasis (PP) are major dermatologic conditions for which phototherapy continues to be a successful and valuable treatment option. UVA‐1 phototherapy is effective in the management of cutaneous T‐cell mediated diseases. The aim of the study was to evaluate the efficacy and safety of low‐dose UVA‐1 phototherapy for the management of PP/early‐stage MF. A total of 30 patients, diagnosed with MF (n:19) or PP (n:11) were enrolled to the study. All patients were managed with low‐dose UVA‐1 (20 or 30 J cm^?2). Response was assessed clinically and immunohistochemically. UVA‐1 treatment led to clinical and histological complete remission (CR) in 11 of 19 MF patients (57.9%), partial remission (PR) in three of 19 (15.8%), after a mean cumulative dose of 1665 (range, 860–3120) J cm^?2 and mean number of 73 exposure (range, 43–107) sessions. Five patients with PP (45.5%) showed CR, and PR was observed in six patients with PP (54.5%) after a mean cumulative dose of 1723 (range, 1060–3030) J cm^?2 and mean number of 74 exposure (range, 53–101) sessions. We conclude that low‐dose UVA‐1 therapy seems to be an effective, safe, and well‐tolerated treatment option for patients with PP/early‐stage MF.     

Improving Photoprotection Attitudes in the Tropics: Sunburn vs Vitamin D

The ultraviolet radiation of type B (the UVB) stimulates both the production of vitamin D (VD) and the incorporation of erythema dose (ED). The UVA also contributes to ED. The turning point between the benefit of producing VD and the harm of incorporating ED cannot be determined easily. However, the casual behavior regarding the exposure to the Sun can be changed in order to improve the protoprotection attitudes and create a trend towards benefit. In the case, people living in the low latitudes should exposure themselves to the Sun for a determined time interval within the noon time and avoid the Sun in other periods. This would produce an adequate amount of VD through the VD dose (207–214 J m^?2) against minimum ED (≈105 J m^?2) for skin type II. For it, unprotected forearms and hands must be exposed to the noon Sun (cloudless) for 11 min (winter) and 5 min (summer). The exposure at other times different from noon can represent increases of up to 24% in ED and up to 12 times in the time interval to be in the Sun in relation to the minimum amounts of both ED and time interval at noon.     

Skin Exposure to Ultraviolet B Rapidly Activates Systemic Neuroendocrine and Immunosuppressive Responses

The back skin of C57BL/6 mice was exposed to a single 400 mJ cm^?2 dose of ultraviolet B (UVB), and parameters of hypothalamic–pituitary–adrenal (HPA) axis in relation to immune activity were tested after 30–90 min following irradiation. Levels of brain and/or plasma corticotropin‐releasing hormone (CRH), β‐endorphin, ACTH and corticosterone (CORT) were enhanced by UVB. Hypophysectomy had no effect on UVB‐induced increases of CORT. Mitogen‐induced IFNγ production by splenocytes from UVB‐treated mice was inhibited at 30, 90 min and after 24 h. UVB also led to inhibition of IL‐10 production indicating an immunosuppressive effect on both Th1 and Th2 cytokines. Conditioned media from splenocytes isolated from UVB‐treated animals had no effect on IFNγ production in cultured normal splenocytes; however, IFNγ increased with conditioned media from sham‐irradiated animals. Sera from UVB‐treated mice suppressed T‐cell mitogen‐induced IFNγ production as compared to sera from sham‐treated mice. IFNγ production was inhibited in splenocytes isolated from UVB‐treated animals with intact pituitary, while stimulated in splenocytes from UVB‐treated hypophysectomized mice. Thus, cutaneous exposure to UVB rapidly stimulates systemic CRH, ACTH, β‐endorphin and CORT production accompanied by rapid immunosuppressive effects in splenocytes that appear to be independent of the HPA axis.