| Objective:Solar ultraviolet(UV)radiation is an unavoidable environmental and physical factor.For human health,UV exposure is a double-edged sword.Appropriate dose of UV exposure is beneficial to human health,but excessive UV exposure is related to the occurrence and development of various eye diseases.Daily solar ultraviolet quantification is the premise of cataractogenesis research,previous quantitative studies on solar ultraviolet light mainly focused on outdoor exposure under strong light conditions.However,UV exposure is a continuous processes,this exposure does not stop completely because of leaving the outdoor environment.Furthermore,humans spend more time engaging in indoor activities than outdoor activities,therefore,indoor exposure is also an important part of daily personal ultraviolet exposure.Individual ocular UV exposure indoors is based on outdoor UV intensity and influenced by the building environment and human activities.Hence,in the current study,we measured the UV exposure in four main orientation rooms in Sanya(lowest-latitude city in mainland China)and Lhasa(highest-elevation city in China)to obtain the maximum exposure of indoor ocular solar UV in China,in addition,the study to explore the influences of window switches,personal position and facial directionDifferent from the horizontal ambient UV exposure,individual ocular UV exposure is closely associated with eyelids and the geometry of the eye.Although human ocular UV irradiance exposure was obtained in the previous study,because of the anatomical position of the anterior chamber/lens and other tissues behind the lens,it remained difficult to obtain solar UV irradiance exposure and absorption characteristics.This study attempted to use a biological exposure model to simulate human ocular solar UV exposure,and we tried to determine the solar UV exposure and absorption of ocular tissue over an entire day and calculated the ratio of total exposure/absorptionUV radiation is divided into three bands,in which UV radiation B(UV-B)photons are five times more efficient in inducing mutations than UV radiation A(UV-A)photons Alpha-crystallin,the most abundant protein in the lens,is essential for maintaining lens transparency.Exposure to UV-B radiation induces DNA damage and repair and triggers alterations in the content of this protein.Lanosterol synthase(LSS),a key rate-limiting enzyme in cholesterol biosynthesis,may play significant roles in oxidative stress and in maintaining lens transparency.However,little is known about the role of LSS in the early stages of UV-B-induced apoptosis.In the study,both animal model and vitro model were used to explore the mechanisms of LSS in the process of oxidative stress induced by UV-B.In summary,this study attempted to establish an indoor and biological exposure model of individual eyes exposed to UV,tried to quantify the indoor UV exposure level and the exposure level of cornea and lens.Moreover,we constructed the animal and vitro models to further explore the alterations of related UV-B induced lens epithelial cell indices in the early stages of injury and the role of LSS in the process of oxidative stress and provided a mechanistic basis for further studying UV-B damage and early prevention of cataracts.Methods:1.This study built a model simulating a standing posture consisting,manikin heads have been frequently used because of the anatomical features of eye.Each manikin had two detectors in the spectrometer:one detector was affixed to the top of the head to measure the horizontal ambient UV,and the other detector was placed tangential to the position of the manikin’s right cornea to measure the ocular UV.Measurements were conducted in four main orientation rooms in Sanya(lowest-latitude city in mainland China)and Lhasa(highest-elevation city in China)to obtain the maximum exposure of indoor ocular solar UV in China.Three monitoring sites were defined in each room 0.5,1.0 and 1.50 m away from the window.Data were collected from each monitoring site at four times corresponding to four states of the manikin eye:the manikin face towards the open window,the back of the manikin head towards the open window,the manikin face towards the closed window,and the back of the manikin head towards the closed window The indoor solar UV irradiance levels of the horizontal ambient line and eye were collected at the same times,meanwhile,indoor and outdoor UV exposure measurements were acquired.The UV exposure intensity,ultraviolet biological effective(UV-BE)intensity and dose were calculated to evaluate the UV exposure level of indoor model eyes.2.The study tried to simulate natural and actual solar exposure of randomization ocular tissue.Therefore,in this study,a dual-detector spectrometer was used to measure ocular exposure of porcine eyes implanted into a manikin at a range of solar elevation angles(SEAs).We measured the solar UV exposure of cornea,anterior chamber/lens and other ocular tissues behind the lens,then,we calculated the UV absorption intensity of cornea and anterior chamber/lens over an entire day.The study reported the exposure/absorption ratio of ocular tissue relative to the environment and demonstrated the absorption characteristics at single wavelengths3.The study constructed an animal model by irradiating female Sprague-Dawley rats with UV-B radiation and homogenate capsules were prepared.A series of related indicators were investigated for evaluation of oxidative stress and apoptosis levels in lens after UV-B irradiation,expression of apoptotic-related proteins was also measured Meanwhile,the effects of UV exposure on LSS expression and proteins that may affect LSS expression level were evaluated.To further explore the function of LSS under UV-B-induced oxidative stress,we cultured HLE cells with LSS protein overexpression and observed the alterations in ROS,crystallin and apoptosis-related factorsResults:1.In the same orientation rooms,the variation trend of UV radiation under different exposure conditions is basically the same in the whole day.The study found that some danger exists from 12° to 37° in the eastward room and from 34° to 9° in the westward room under the open window condition in Lhasa.In addition,the accumulated UV exposure in the southward room in Sanya from 67° to 88° warrants attention Furthermore,we found that UV exposure indoors was greater at the manikin eye than that at the horizontal ambient line,and the individual UV exposure level was also influenced by human activities2.This study showed that normal solar UV irradiance exposure and absorption of the cornea and anterior chamber/lens follow a bimodal curve over an entire day Subsequently,we demonstrated that the cornea was exposed to one-half the horizontal ambient UV irradiance,and the anterior chamber/lens was exposed to one-fifth the horizontal ambient UV irradiance.A linear relationship was found between absorption irradiance and exposure irradiance in both the cornea and the anterior chamber/lens3.UV-B exposure induced oxidative stress and apoptosis in rat lens epithelial cells and that the level of lenticular damage increased with irradiance exposure.Additionally,the alpha-crystallin content decreased,while Bax and cleaved Caspase-3 expression levels increased compared with those of the control.Furthermore,reactive oxygen species overproduction activated the Sirtuin 1(Sirt1)/sterol regulatory element binding transcription factor 2(SREBF2)pathway,inducing 3-hydroxy-3-methyl glutaryl coenzyme A reductase(HMGCR)and LSS expression.In the group with HLE cells overexpressing LSS,the ROS level,apoptosis-related index was decreased and the crystallin was increased compared with that of the controlConclusion:1.There are some danger exists from 12° to 37° in the eastward-oriented rooms and from 34° to 9° in westward-oriented rooms under the open window condition in Lhasa,meanwhile in the southward-oriented room from 67° to 88° in Sanya.Indoor UV exposure was greater at the manikin eye than that at the horizontal ambient line under the same exposure condition and was influenced by individual activities2.The maximum irradiance exposures of the cornea and anterior chamber/lens tissue were lower than those from ambient exposure.The absorbance of ocular tissue changed with SEA under sunlight3.UV-B exposure induced oxidative damage,resulting in crystallin denaturation and lens epithelial cell apoptosis.LSS may play a protective role in the early stages of this process and may regulate it via the Sirtl. |
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