Light sensitivity of carotenoids used as food colours

1990 ◽  
Vol 190 (4) ◽  
pp. 306-313 ◽  
Author(s):  
Kevin J�rgensen ◽  
Leif H. Skibsted
1985 ◽  
Vol 55 ◽  
Author(s):  
Miguel F. Refojo

ABSTRACTImplants are essential for the repair of retinal detachments. The implant buckles the wall of the eye and apposes the detached retina with the choroid, thus restoring light sensitivity to the retina. The scleral buckling also relieves traction on the retina from a shrinking vitreous body. The implant materials most commonly used are solid silicone rubber and silicone sponges, but both types have some disadvantages. A poly(hydroxyethyl acrylate-co-methyl acrylate) hydrogel implant with improved properties of softness and antibiotic absorption is also available for retinal detachment surgery. Proliferative vitreoretinopathy involves various conditions of retinal detachment complicated by vitreous fibrosis, which, after vitrectomy, may be treated with intraocular injection of fluids that support the retina against the choroid. For conditions requiring a long-term implant, silicone oil although controversial is the material of choice. Many other substances have been investigated but none better has yet been found.


Author(s):  
NYu Mal’kova ◽  
MD Petrova

Summary. Introduction: Visual fatigue is caused by changes in the muscular apparatus and retina of the eye and is characterized by deterioration in their functional activity. Along with an increase in work experience and age, workplace visual stress promotes the loss of performance. Known methods of visual fatigue prevention and eye strain relief are ineffective. In this regard, a technique of relieving visual fatigue using scattered low-level red laser radiation was developed and patented. The purpose of our study was a retrospective evaluation of effectiveness of the visual fatigue reduction technique. Materials and methods: We examined two groups of women (PC operators and jewellers) aged 43–57 years experiencing visual stress at work and practicing the method under study over the previous 20 years. The state of daylight vision was assessed by adaptation time. Results: A five-day testing of the method of visual fatigue relief showed stabilization of the light sensitivity threshold throughout the work shift. Over the 20-year period, the female workers had had no complaints of eye strain, burning or lacrimation. Objective studies of the functional state of the organ of sight showed that the light sensitivity threshold during the working day in two study groups was significantly lower than that in the control group with no preventive measures taken. Conclusions: We established that using the technique of eye strain relief based on a two-minute binocular exposure to red laser radiation with the power density of 2×10–7 W/cm2, a 5-day course every six months over the period of 20 years, helped retain retinal activity in terms of light sensitivity, thus preventing visual fatigue.


BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yuehui Tian ◽  
Georg Nagel ◽  
Shiqiang Gao

Abstract Background Microbial rhodopsins vary in their chemical properties, from light sensitive ion transport to different enzymatic activities. Recently, a novel family of two-component Cyclase (rhod)opsins (2c-Cyclop) from the green algae Chlamydomonas reinhardtii and Volvox carteri was characterized, revealing a light-inhibited guanylyl cyclase (GC) activity. More genes similar to 2c-Cyclop exist in algal genomes, but their molecular and physiological functions remained uncharacterized. Results Chlamyopsin-5 (Cop5) from C. reinhardtii is related to Cr2c-Cyclop1 (Cop6) and can be expressed in Xenopus laevis oocytes, but shows no GC activity. Here, we exchanged parts of Cop5 with the corresponding ones of Cr2c-Cyclop1. When exchanging the opsin part of Cr2c-Cyclop1 with that of Cop5, we obtained a bi-stable guanylyl cyclase (switch-Cyclop1) whose activity can be switched by short light flashes. The GC activity of switch-Cyclop1 is increased for hours by a short 380 nm illumination and switched off (20-fold decreased) by blue or green light. switch-Cyclop1 is very light-sensitive and can half-maximally be activated by ~ 150 photons/nm2 of 380 nm (~ 73 J/m2) or inhibited by ~ 40 photons/nm2 of 473 nm (~ 18 J/m2). Conclusions This engineered guanylyl cyclase is the first light-switchable enzyme for cGMP level regulation. Light-regulated cGMP production with high light-sensitivity is a promising technique for the non-invasive investigation of the effects of cGMP signaling in many different tissues.


2012 ◽  
Vol 93 (8) ◽  
pp. 2022-2027 ◽  
Author(s):  
Michelle A Crinó ◽  
Claire N Heenan ◽  
Minh H Nguyen ◽  
Costas E Stathopoulos

1983 ◽  
Vol 24 (5) ◽  
pp. 933-936 ◽  
Author(s):  
P.R.M. Shannon ◽  
R.A. Jeavons ◽  
B.C. Jarvis
Keyword(s):  

1960 ◽  
Vol 15 (7) ◽  
pp. 460-465 ◽  
Author(s):  
Irmgard Ziegler
Keyword(s):  

A tetrahydrobiopterin-compound (in addition to biopterin) has been found in the eyes and skins of Amphibians as well as in the eyes of insects. Evidence is given that this tetrahydrobiopterin-compound occurs as a N (8) -ribosid. The compound originally does not fluoresce. It is very light-sensitive; by irradiation hydrogen is split off, which can be transferred to TTC, and the fluorescing degradationproducts appear. The possibility of a tetrahydro-dihydro-equilibrium and the importance of this widely distributed compound for light-sensitivity is discussed.


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