Importance of tissue transglutaminase in repair of extracellular matrices and cell death of dermal fibroblasts after exposure to a solarium ultraviolet A source

Investigations were undertaken to study the role of the protein cross-linking enzyme tissue transglutaminase in changes associated with the extracellular matrix and in the cell death of human dermal fibroblasts following exposure to a solarium ultraviolet A source consisting of 98.8% ultraviolet A and 1.2% ultraviolet B. Exposure to nonlethal ultraviolet doses of 60 to 120 kJ per m2 resulted in increased tissue transglutaminase activity when measured either in cell homogenates, "in situ" by incorporation of fluorescein-cadaverine into the extracellular matrix or by changes in the epsilon(gamma-glutamyl) lysine cross-link. This increase in enzyme activity did not require de novo protein synthesis. Incorporation of fluorescein-cadaverine into matrix proteins was accompanied by the cross-linking of fibronectin and tissue transglutaminase into nonreducible high molecular weight polymers. Addition of exogenous tissue transglutaminase to cultured cells mimicking extensive cell leakage of the enzyme resulted in increased extracellular matrix deposition and a decreased rate of matrix turnover. Exposure of cells to 180 kJ per m2 resulted in 40% to 50% cell death with dying cells showing extensive tissue transglutaminase cross-linking of intracellular proteins and increased cross-linking of the surrounding extracellular matrix, the latter probably occurring as a result of cell leakage of tissue transglutaminase. These cells demonstrated negligible caspase activation and DNA fragmentation but maintained their cell morphology. In contrast, exposure of cells to 240 kJ per m2 resulted in increased cell death with caspase activation and some DNA fragmentation. These cells could be partially rescued from death by addition of caspase inhibitors. These data suggest that changes in cross-linking both in the intracellular and extracellular compartments elicited by tissue transglutaminase following exposure to ultraviolet provides a rapid tissue stabilization process following damage, but as such may be a contributory factor to the scarring process that results.

Ultraviolet damage to the eye revisited:eye-sun protection factor (E-SPF®), a new ultraviolet protection label for eyewear

Ultraviolet (UV) radiation potentially damages the skin, the immune system, and structures of the eye. A useful UV sun protection for the skin has been established. Since a remarkable body of evidence shows an association between UV radiation and damage to structures of the eye, eye protection is important, but a reliable and practical tool to assess and compare the UV-protective properties of lenses has been lacking. Among the general lay public, misconceptions on eye-sun protection have been identified. For example, sun protection is mainly ascribed to sunglasses, but less so to clear lenses. Skin malignancies in the periorbital region are frequent, but usual topical skin protection does not include the lids. Recent research utilized exact dosimetry and demonstrated relevant differences in UV burden to the eye and skin at a given ambient irradiation. Chronic UV effects on the cornea and lens are cumulative, so effective UV protection of the eyes is important for all age groups and should be used systematically. Protection of children's eyes is especially important, because UV transmittance is higher at a very young age, allowing higher levels of UV radiation to reach the crystalline lens and even the retina. Sunglasses as well as clear lenses (plano and prescription) effectively reduce transmittance of UV radiation. However, an important share of the UV burden to the eye is explained by back reflection of radiation from lenses to the eye. UV radiation incident from an angle of 135°-150° behind a lens wearer is reflected from the back side of lenses. The usual antireflective coatings considerably increase reflection of UV radiation. To provide reliable labeling of the protective potential of lenses, an eye-sun protection factor (E-SPF®) has been developed. It integrates UV transmission as well as UV reflectance of lenses. The E-SPF® compares well with established skin-sun protection factors and provides clear messages to eye health care providers and to lay consumers. © 2014 Behar-Cohen et al, This work is published by Dove Medical Press Ltd.

Effect of disability glare on visual performance

The object of the study was to investigate, establish and quantify the relationship between contrast sensitivity, intraocular light scatter and glare. The aim was to establish the effects on vision, in an effort to provide a more comprehensive understanding of the visual world of subjects prone to increased light scatter in the eye. Disability glare refers to the reduction in visual performance produced by a glare source. The reduction in visual performance can be explained by intraocular scattered light producing a veiling luminance which is superimposed upon the retinal image. This veiling luminance lowers contrast thus sensitivity to the stimulus declines. The effect of glare of luminance and colour contrast sensitivity for young and elderly subjects was examined. For both age groups, disability glare was greatest for the red-green stimulus and least for the blue-yellow. The precise effect of a glare source on colour discrimination depends upon the interaction between the chromaticity of the glare source and that of the stimulus. The effect of a long wavelength pass (red) and a short wavelength pass filter (blue) on disability glare was examined. Disability glare was not significantly different with the red and blue filters, even in the presence of wavelength dependent scatter. An equation was derived which allowed an intrinsic Light Scatter Factor (LSF) to be determined for any given glare angle (Paulsson and Sjöstrand, 1980). Corrections to the formula to account for factors such as pupil size changes are unnecessary. The results confirm the suitability of measuring the LSF using contrast threshold with and without glare, provided that appropriate methods are used. Using this formula an investigation into the amount of wavelength dependent scatter indicated that wavelength dependent scatter in normal young, elderly or cataractous eyes is of little or no significance. Finally, it seemed desirable to investigate the effect ultraviolet (UV) radiation has on intraocular light scatter and subsequently visual performance. Overall the results indicated that the presence or absence of UV radiation has relatively little effect on visual function for the young, elderly or cataract patient.

Fiber Bragg gratings of type I in SMF-28 and B/Ge fibre and type IIA B/Ge fibre under gamma radiation up to 0.54 MGy

The sensitivities of type I and IIA fibre Bragg gratings written to different reflectivities in SMF-28 and B/Ge fibres to ionizing radiation up to 0.54MGy are investigated. The Bragg wavelength shows a small and rapid increase at the start of irradiation followed by either a plateau (type I) or a decrease (type IIA).

High accuracy interrogation of a WDM FBG sensor array using radiation modes from a B-FBG

We report the development of a WDM optical sensor array interrogation system using the radiation modes from a BFBG. We present results indicating 70nm bandwidth, with 0.2um RMS noise and a minimum WDM spacing of 30um. We further show the system to be polarization independent.

Fiber Bragg gratings of type I in SMF-28 and B/Ge fibre and type IIA B/Ge fibre under gamma radiation up to 0.54 MGy

The sensitivities of type I and IIA fibre Bragg gratings written to different reflectivities in SMF-28 and B/Ge fibres to ionizing radiation up to 0.54MGy are investigated. The Bragg wavelength shows a small and rapid increase at the start of irradiation followed by either a plateau (type I) or a decrease (type IIA).