The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

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Relevance of Lipid-Based Products in the Management of Dry Eye Disease

Components of the ocular surface synergistically contribute to maintaining and protecting a smooth refractive layer to facilitate the optimal transmission of light. At the air-water interface, the tear film lipid layer (TFLL), a mixture of lipids and proteins, plays a key role in tear surface tension and is important for the physiological hydration of the ocular surface and for ocular homeostasis. Alterations in tear fluid rheology, differences in lipid composition, or downregulation of specific tear proteins are found in most types of ocular surface disease, including dry eye disease (DED). Artificial tears have long been a first line of treatment in DED and aim to replace or supplement tears. More recently, lipid-containing eye drops have been developed to more closely mimic the combination of aqueous and lipid layers of the TFLL. Over the last 2 decades, our understanding of the nature and importance of lipids in the tear film in health and disease has increased substantially. The aim of this article is to provide a brief overview of our current understanding of tear film properties and review the effectiveness of lipid-based products in the treatment of DED. Liposome lid sprays, emulsion eye drops, and other lipid-containing formulations are discussed.Peer reviewe

Crystalline Wax Esters Regulate the Evaporation Resistance of Tear Film Lipid Layers Associated with Dry Eye Syndrome

Dry eye syndrome (DES), one of the most common ophthalmological diseases, is typically caused by excessive evaporation of tear fluid from the ocular surface. Excessive evaporation is linked to impaired function of the tear film lipid layer (TFLL) that covers the aqueous tear film. The principles of the evaporation resistance of the TFLL have remained unknown, however. We combined atomistic simulations with Brewster angle microscopy and surface potential experiments to explore the organization and evaporation resistance of films composed of wax esters, one of the main components of the TFLL. The results provide evidence that the evaporation resistance of the TFLL is based on crystalline-state layers of wax esters and that the evaporation rate is determined by defects in the TFLL and its coverage on the ocular surface. On the basis of the results, uncovering the nonequilibrium spreading and crystallization of TFLL films has potential to reveal new means of treating DES.Peer reviewe

Climatic droplet keratopathy: An old disease in new clothes

Climatic droplet keratopathy (CDK) is an acquired and potentially handicapping cornea degenerative disease that is highly prevalent in certain rural communities around the world. It predominantly affects males over their forties. It has many other names such as Bietti's band-shaped nodular dystrophy, Labrador keratopathy, spheroidal degeneration, chronic actinic keratopathy, oil droplet degeneration, elastoid degeneration and keratinoid corneal degeneration. CDK is characterized by the haziness and opalescence of the cornea's most anterior layers which go through three stages with increasing severity. Globular deposits of different sizes may be histopathologically observed under the corneal epithelium by means of light and electron microscopy. The coalescence and increased volume of these spherules may cause the disruption of Bowman's membrane and the elevation and thinning of the corneal epithelium. The exact aetiology and pathogenesis of CDK are unknown, but they are possibly multifactorial. The only treatment in CDK advanced cases is a corneal transplantation, which in different impoverished regions of the world is not an available option. Many years ago, the clinical and histological aspects of this disease were described in several articles. This review highlights new scientific evidence of the expanding knowledge on CDK's pathogenesis which will open the prospect for new therapeutic interventions.Fil: Serra, Horacio Marcelo. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Holopainen, Juha M.. University of Helsinski; FinlandiaFil: Beuerman, Roger. Singapore Eye Research Institute; Singapur. Yong Loo Lin School of Medicine; SingapurFil: Kaarniranta, Kai. University of Eastern Finland and Kuopio University Hospital; FinlandiaFil: Suarez, Maria Fernanda. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Urrets Zavalía, Julio Alberto. Universidad Católica de Córdoba. Facultad de Medicina. Clínica Universitaria Reina Fabiola; Argentin

Characterization of Mixed Monolayers of Phosphatidylcholine and a Dicationic Gemini Surfactant SS-1 with a Langmuir Balance: Effects Of DNA

AbstractMonolayers of a cationic gemini surfactant, 2,3-dimethoxy-1,4-bis(N-hexadecyl-N;N-dimethyl-ammonium)butane dibromide (abbreviated as SS-1) and its mixtures with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were studied using a Langmuir balance. More specifically, we measured the force-area (π-A) curves and determined the elastic area compressibility modulus (Cs−1) as a function of lateral packing pressure and the mole fraction of the cationic lipid (XSS-1), with and without DNA in the subphase. Both SS-1 and POPC exhibited smooth compression isotherms, indicating their monolayers to be in the liquid expanded state. Even low contents (XSS-1<0.05) of SS-1 in a POPC monolayer condensed the film dramatically, up to 20% at 30mN/m. This effect is suggested to reflect reorientation of the P−-N+ dipole of the POPC headgroup. Accordingly, the magnitude of the condensing effect diminishes with XSS-1 and is not observed for mixed films of dioleoylglycerol and SS-1. Reorientation of the P−-N+ dipole is further supported by the pronounced increase in monolayer dipole potential ψ due to SS-1. The presence of DNA in the subphase affected the mixed POPC/SS-1 monolayers differently depending on the constituent lipid stoichiometry as well as on the DNA/SS-1 charge ratio. At a DNA concentration of 0.63μM (in base pairs) condensation of neat POPC monolayers was evident, and this effect remained up to XSS-1<0.5, corresponding to DNA/SS-1 charge ratio of 1.25. An expansion due to DNA, evident as an increase in ΔA/molecule, was observed at XSS-1>0.5. At a higher concentration of DNA (1.88μM base pairs) in the subphase corresponding to DNA/SS-1 charge ratio of 3.75 at XSS-1=0.5, condensation was observed at all values of XSS-1

The genetic variant rs4073 A→T of the Interleukin-8 promoter region is associated with the earlier onset of exudative age-related macular degeneration

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Predicting the Properties of Industrially Produced Oat Flours by the Characteristics of Native Oat Grains or Non-Heat-Treated Groats

The aim of this study was to determine whether the properties of the native oat grain or non-heat-treated groats (laboratory-scale dehulling) can be used to predict the quality of the industrially produced oat flour produced from heat-treated groats. Quality properties such as the color, hectoliter weight, thousand seed weight and hull content of Finnish native grains (n = 30) were determined. Furthermore, the relationship between the properties of the native grains and the chemical composition of the raw oat materials before and after the milling process were studied. A significant relationship (p < 0.01) was observed between the thousand seed weight of the native oat groats and the chemical composition of the industrially produced oat flour. Furthermore, the protein content of the native grains measured by NIT correlated with the chemical composition of the oat flours. These results suggest that the properties of oat flour produced on an industrial scale, including heat treatment, could be predicted based on the properties of native oat grains

Predicting the Properties of Industrially Produced Oat Flours by the Characteristics of Native Oat Grains or Non-Heat-Treated Groats

The aim of this study was to determine whether the properties of the native oat grain or non-heat-treated groats (laboratory-scale dehulling) can be used to predict the quality of the industrially produced oat flour produced from heat-treated groats. Quality properties such as the color, hectoliter weight, thousand seed weight and hull content of Finnish native grains (n = 30) were determined. Furthermore, the relationship between the properties of the native grains and the chemical composition of the raw oat materials before and after the milling process were studied. A significant relationship (p < 0.01) was observed between the thousand seed weight of the native oat groats and the chemical composition of the industrially produced oat flour. Furthermore, the protein content of the native grains measured by NIT correlated with the chemical composition of the oat flours. These results suggest that the properties of oat flour produced on an industrial scale, including heat treatment, could be predicted based on the properties of native oat grains

Kuljettajan sairaus kuolonkolarien aiheuttajana

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Visualizing spatial lipid distribution in porcine lens by MALDI imaging high-resolution mass spectrometry

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