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Sample records for tear-film lipid layer

  1. Tear film lipid layer: A molecular level view

    Czech Academy of Sciences Publication Activity Database

    Cwiklik, Lukasz

    2016-01-01

    Roč. 1858, č. 10 (2016), s. 2421-2430 ISSN 0005-2736 R&D Projects: GA ČR GA15-14292S Institutional support: RVO:61388955 Keywords : tear film * tear film lipid layer * molecular dynamics simulations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.498, year: 2016

  2. Interaction of lysozyme with a tear film lipid layer model: A molecular dynamics simulation study.

    Science.gov (United States)

    Wizert, Alicja; Iskander, D Robert; Cwiklik, Lukasz

    2017-12-01

    The tear film is a thin multilayered structure covering the cornea. Its outermost layer is a lipid film underneath of which resides on an aqueous layer. This tear film lipid layer (TFLL) is itself a complex structure, formed by both polar and nonpolar lipids. It was recently suggested that due to tear film dynamics, TFLL contains inhomogeneities in the form of polar lipid aggregates. The aqueous phase of tear film contains lachrymal-origin proteins, whereby lysozyme is the most abundant. These proteins can alter TFLL properties, mainly by reducing its surface tension. However, a detailed nature of protein-lipid interactions in tear film is not known. We investigate the interactions of lysozyme with TFLL in molecular details by employing coarse-grained molecular dynamics simulations. We demonstrate that lysozyme, due to lateral restructuring of TFLL, is able to penetrate the tear lipid film embedded in inverse micellar aggregates. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Behavior of sphingomyelin and ceramide in a tear film lipid layer model

    Czech Academy of Sciences Publication Activity Database

    Olžyńska, A.; Cwiklik, Lukasz

    2017-01-01

    Roč. 210, March (2017), s. 128-134 ISSN 0940-9602 Institutional support: RVO:61388963 Keywords : tear film lipid layer * molecular dynamics simulations * Langmuir balance * sphingomyelin * ceramide Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.864, year: 2016

  4. Behavior of sphingomyelin and ceramide in a tear film lipid layer model

    Czech Academy of Sciences Publication Activity Database

    Olžyńska, Agnieszka; Cwiklik, Lukasz

    2017-01-01

    Roč. 210, MAR 2017 (2017), s. 128-134 ISSN 0940-9602 R&D Projects: GA ČR GA15-14292S Institutional support: RVO:61388955 Keywords : Molecular dynamics simulations * Sphingomyelin * Tear film lipid layer Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.864, year: 2016

  5. Clinical performance of an objective methodology to categorize tear film lipid layer patterns

    Science.gov (United States)

    Garcia-Resua, Carlos; Pena-Verdeal, Hugo; Giraldez, Maria J.; Yebra-Pimentel, Eva

    2017-08-01

    Purpose: To validate the performance of a new objective application designated iDEAS (Dry Eye Assessment System) to categorize different zones of lipid layer patterns (LLPs) in one image. Material and methods: Using the Tearscopeplus and a digital camera attached to a slit-lamp, 50 images were captured and analyzed by 4 experienced optometrists. In each image the observers outlined tear film zones that they clearly identified as a specific LLP. Further, the categorization made by the 4 optometrists (called observer 1, 2, 3 and 4) was compared with the automatic system included in iDEAS (5th observer). Results: In general, observer 3 classified worse than all observers (observers 1, 2, 4 and automatic application, Wilcoxon test, 0.05). Furthermore, we obtained a set of photographs per LLP category for which all optometrists showed agreement by using the new tool. After examining them, we detected the more characteristic features for each LLP to enhance the description of the patterns implemented by Guillon. Conclusions: The automatic application included in the iDEAS framework is able to provide zones similar to the annotations made by experienced optometrists. Thus, the manual process done by experts can be automated with the benefits of being unaffected by subjective factors.

  6. Structure-function relationship of tear film lipid layer: A contemporary perspective.

    Science.gov (United States)

    Georgiev, Georgi As; Eftimov, Petar; Yokoi, Norihiko

    2017-10-01

    Tear film lipid layer (TFLL) stabilizes the air/tear surface of the human eye. Meibomian gland dysfunction (MGD) resulting in quantitative and qualitative modifications of TFLL major (>93%) component, the oily secretion of meibomian lipids (MGS), is the world leading cause of dry eye syndrome (DES) with up to 86% of all DES patients showing signs of MGD. Caused by intrinsic factors (aging, ocular and general diseases) and by extrinsic everyday influences like contact lens wear and extended periods in front of a computer screen, DES (resulting in TF instability, visual disturbances and chronic ocular discomfort) is the major ophthalmic public health disease of the present time affecting the quality of life of 10-30% of the human population worldwide. Therefore there is a pressing need to summarize the present knowledge, contradictions and open questions to be resolved in the field of TFLL composition/structure/functions relationship. The following major aspects are covered by the review: (i) Do we have a reliable mimic for TFLL: MGS vs contact lens lipid extracts (CLLE) vs lipid extracts from whole tears. Does TFLL truly consist of lipids only or it is important to keep in mind the TF proteins as well?; (ii) Structural properties of TFLL and of its mimics in health and disease in vitro and in vivo. How the TFLL uniformity and thickness ensures the functionality of the lipid layer (barrier to evaporation, surface properties, TF stability etc.); (iii) What are the main functions of the TFLL? In this aspect an effort is done to emphasize that there is no single main function of TFLL but instead it simultaneously fulfills plethora of functions: suppresses the evaporation (alone or probably in cooperation with other TF constituents) of the aqueous tears; stabilizes (due to its surface properties) the air/tear surface at eye opening and during the interblink interval; and even acts as a first line of defense against bacterial invasion due to its detergency action on the

  7. [Epidemiologic study of tear film lipid layer thickness measurement in the population of Taishitun Community in Beijing].

    Science.gov (United States)

    Liang, Q F; Du, X H; Su, Y D; Wang, N L; Wei, Z J; Labbé, Antoine

    2017-07-11

    Objective: To investigate the distribution of tear film lipid layer thickness (LLT) and the relationship between symptoms and signs of dry eye and tear film LLT in the population of Taishitun Community in Beijing. Methods: A cross-sectional study. From May 2016 to August 2016, three streets of Taishitun Community were randomly selected as survey districts and 540 persons were taken as investigation subjects. Every participant completed 6 items of dry eye examinations as follows: questionnaire (Ocular Surface Disease Index, OSDI), measurement of tear film LLT, tear film break-up time (TBUT), corneal and conjunctival staining, SchirmerⅠtest and the infrared meibomian photography. According to their age, all participants were divided into four groups: junior group (analysis and multivariate Logistic regression analysis, distribution of the variables of LLT and the relationship between dry eye symptoms and LLT were studied. Results: A total of 473 residents finally participated in this study, and the response ratio was 87.6%. The values of LLT were normally distributed. The average LLT was (59.87±18.50) nm [(60.16±19.15) nm in males and (59.67±18.57) nm in females], and the comparison of LLT with different genders was not statistically significant ( t= 0.198, P= 0.843). The tear film LLT of four different age groups had statistical significance ( F= 15.092, P0.05. F= 0.538, P >0.05). In the OSDI symptom questionnaire, only blurred vision and decreased visual acuity were related to the tear film LLT ( Pfilm LLT ( P> 0.05). Conclusions: In Taishitun Community of Beijing, the values of tear film LLT had a normal distribution. The LLT was positively correlated with age, but inversely correlated with the severity of the symptoms of dry eye. There was no significant correlation between the LLT and the TBUT, SchirmerⅠtest result and meibomian gland loss rate. (Chin J Ophthalmol, 2017, 53: 495-501) .

  8. Analysis of Factors Associated With the Tear Film Lipid Layer Thickness in Normal Eyes and Patients With Dry Eye Syndrome.

    Science.gov (United States)

    Jung, Ji Won; Park, Si Yoon; Kim, Jin Sun; Kim, Eung Kweon; Seo, Kyoung Yul; Kim, Tae-Im

    2016-08-01

    To determine the effects of clinical variables, including age, sex, history of refractive or cataract surgery, contact lens use, and ocular surface and meibomian gland parameters on the lipid layer thickness (LLT) in normal subjects and patients with dry eye syndrome (DES). A total of 64 normal subjects and 326 patients with DES were enrolled, and they underwent measurements of LLT with a LipiView interferometer and tear meniscus height using optical coherence tomography, tear film break-up time (TBUT) determination, ocular surface staining, Schirmer's test, examination of the lid margins and meibomian glands, and assessment using the Ocular Surface Disease Index (OSDI). In normal subjects, the median (range) LLT was 67 (33-100) nm, and age was the only factor that was significantly associated with LLT (β = 0.678, P = 0.028). In patients with DES, the median (range) LLT was 84 (20-100) nm, and 79.0% of the participants fulfilled the diagnostic criteria for meibomian gland dysfunction (MGD). In a multivariate analysis, increased age and female sex were significantly related to increased LLT (β = 0.282, P = 0.005 and β = 11.493, P < 0.001), and hypersecretory MGD and lid margin inflammation were independently associated with increased LLT (β = 11.299, P = 0.001 and β = 12.747, P = 0.001). Lipid layer thickness measurements using a new interferometer are significantly affected by demographic factors such as age, sex, ocular surgical history, and MGD type. Therefore, all of these factors must be considered in the diagnosis of ocular surface diseases.

  9. The Effect of Polar Lipids on Tear Film Dynamics

    KAUST Repository

    Aydemir, E.; Breward, C. J. W.; Witelski, T. P.

    2010-01-01

    In this paper, we present a mathematical model describing the effect of polar lipids, excreted by glands in the eyelid and present on the surface of the tear film, on the evolution of a pre-corneal tear film. We aim to explain the interesting

  10. The Effect of Polar Lipids on Tear Film Dynamics

    KAUST Repository

    Aydemir, E.

    2010-06-17

    In this paper, we present a mathematical model describing the effect of polar lipids, excreted by glands in the eyelid and present on the surface of the tear film, on the evolution of a pre-corneal tear film. We aim to explain the interesting experimentally observed phenomenon that the tear film continues to move upward even after the upper eyelid has become stationary. The polar lipid is an insoluble surface species that locally alters the surface tension of the tear film. In the lubrication limit, the model reduces to two coupled non-linear partial differential equations for the film thickness and the concentration of lipid. We solve the system numerically and observe that increasing the concentration of the lipid increases the flow of liquid up the eye. We further exploit the size of the parameters in the problem to explain the initial evolution of the system. © 2010 Society for Mathematical Biology.

  11. Organization of lipids in the tear film: a molecular-level view.

    Directory of Open Access Journals (Sweden)

    Alicja Wizert

    Full Text Available Biophysical properties of the tear film lipid layer are studied at the molecular level employing coarse grain molecular dynamics (MD simulations with a realistic model of the human tear film. In this model, polar lipids are chosen to reflect the current knowledge on the lipidome of the tear film whereas typical Meibomian-origin lipids are included in the thick non-polar lipids subphase. Simulation conditions mimic those experienced by the real human tear film during blinks. Namely, thermodynamic equilibrium simulations at different lateral compressions are performed to model varying surface pressure, and the dynamics of the system during a blink is studied by non-equilibrium MD simulations. Polar lipids separate their non-polar counterparts from water by forming a monomolecular layer whereas the non-polar molecules establish a thick outermost lipid layer. Under lateral compression, the polar layer undulates and a sorting of polar lipids occurs. Moreover, formation of three-dimensional aggregates of polar lipids in both non-polar and water subphases is observed. We suggest that these three-dimensional structures are abundant under dynamic conditions caused by the action of eye lids and that they act as reservoirs of polar lipids, thus increasing stability of the tear film.

  12. [Assessment of lipid layer thickness of tear film in the diagnosis of dry-eye syndrome in children after the hematopoietic stem cell transplantation].

    Science.gov (United States)

    Kurpińska, Małgorzata; Gorczyńska, Ewa; Owoc-Lempach, Joanna; Bernacka, Aleksandra; Misiuk-Hojło, Marta; Chybicka, Alicja

    2011-01-01

    Dry eye syndrome (DES), also known as keratoconjunctivitis sicca (KCS) is recognized as the most frequent ocular complication after allogeneic stem cell transplantation (allo-SCT). KCS can appear either due to insufficient tear production or excessive tear evaporation, both resulting in tears hyperosmolarity that leads to ocular damage. The evaporation rate and better film stability is determined primarily by the status of the lipid layer. Observation and classification of tear film lipid layer interference patterns in normal and dry eyes in patients after allogeneic stem cell transplantation with a follow-up time of 6 months-5 years (median 26.54 months). Investigation of the relation between the lipid layer interference patterns in normal and dry eyes and the results of other dry eye examinations and complaints. Relation between DES and conditioning regimes, including total body irradiation and high-dose chemotherapy, immunosuppressive drugs, the time after allogeneic stem cell transplantation and chronic graft-versus-host disease. Precorneal tears lipid layer interference patterns, were examined in 114 eyes in treatment group with the Tearscope-plus. Patient with dry eye were identified on the basis of Schirmer test scores and/or tear breakup time, and positive lissamine and/or fluorescein staining. 42 of 114 eyes (36.8%) developed DES after allo-SCT A significant correlation between thickness of lipid layer and BUT, Schirmer test, lissamine green and fluorescein staining was found in the treatment group. A significant association was found between present chronic GVHD and DES in children. DES was not associated with TBI, corticosteroids, immunosuppressive drugs and the time in the present study. Tears lipid layer interference patterns are highly correlated with the diagnosis of DES. Tears lipid layer interference patterns ( noninvasive method), can be used to diagnose early DES in children after allo-SCT. Chronic GVHD play a major role in development of DES

  13. Effect of lipid-based dry eye supplements on the tear film in wearers of eye cosmetics.

    Science.gov (United States)

    Wang, Michael T M; Cho, Irene Sung Hee; Jung, Soo Hee; Craig, Jennifer P

    2017-08-01

    To compare the effects on tear film parameters and contamination in cosmetic eyeliner wearers, after single application of two lipid-based dry eye treatments: a lipid-containing lubricant eye drop and a phospholipid liposomal spray. Fifty participants were enrolled in a prospective, randomised, paired-eye, investigator-masked trial. Pencil eyeliner (Body Shop ® Crayon Eye Definer) was applied to the upper eyelid periocular skin of both eyes, anterior to the lash line. Baseline tear film quality was assessed fifteen minutes after eyeliner application. A lubricant drop (Systane ® Balance) was then applied to one eye (randomised), and liposomal spray (Tears Again ® ) to the contralateral eye. Tear film contamination, lipid layer grade, non-invasive tear film break-up time and tear evaporation rate were evaluated fifteen minutes post-treatment and compared to pre-treatment values. Pre-treatment measurements did not differ between eyes assigned to lubricant drop and liposomal spray. Tear film contamination was observed in a greater proportion of eyes following both treatments (both p0.05). Changes in tear film parameters did not differ between treatments (all p>0.05). Both the lipid-containing lubricant eye drop and phospholipid liposomal spray result in clinically apparent tear film contamination in eyeliner cosmetic wearers. Although both treatments effected an increase in lipid layer thickness, neither displayed clinical efficacy in improving tear film stability. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  14. Automated Measurement of Tear Film Dynamics and Lipid Layer Thickness for Assessment of Non-Sjögren Dry Eye Syndrome With Meibomian Gland Dysfunction.

    Science.gov (United States)

    Ji, Yong Woo; Lee, Jeihoon; Lee, Hun; Seo, Kyoung Yul; Kim, Eung Kweon; Kim, Tae-Im

    2017-02-01

    To investigate automated values from an advanced corneal topographer with a built-in real keratometer, color camera, and ocular surface interferometer for the evaluation of non-Sjögren dry eye syndrome (NSDES) with meibomian gland dysfunction (MGD). Sixty-four patients (64 eyes) diagnosed with NSDES with MGD were enrolled. All eyes were evaluated using the Ocular Surface Disease Index (OSDI), fluorescence staining score, tear film breakup time (TBUT), Schirmer test, and MGD grade. Noninvasive Keratograph average tear film breakup time (NIKBUTav), tear meniscus height (TMHk), meibomian gland (MG) dropout grade, and lipid layer thickness (LLT) using interferometry were measured. Among automated indexes, NIKBUTav (mean 7.68 ± 4.07 s) and the MG dropout grade (mean 1.0 ± 0.5) significantly correlated with the OSDI (mean 40.6 ± 22.9) (r = -0.337, P = 0.006; and r = 0.201, P = 0.023, respectively), as did all conventional indicators, except the Schirmer score (mean 9.1 ± 5.9 mm). TMHk (mean 0.21 ± 0.18 mm) had significant correlation with the Schirmer score, the staining score (mean 1.2 ± 0.7), TBUT (mean 3.8 ± 1.8 s), and NIKBUTav (r = 0.298, P = 0.007; r = -0.268, P = 0.016; r = 0.459, P < 0.001; and r = 0.439, P < 0.001, respectively), but not any MGD indicator, even the MG dropout grade. NIKBUTav showed significant correlations with all clinical parameters and other automated values, except the Schirmer score and LLT (mean 83.94 ± 20.82 nm) (all (Equation is included in full-text article.)≥ 0.25 and P < 0.01). The MG dropout grade highly correlated with all indexes except TMHk (all (Equation is included in full-text article.)≥ 0.25 and P < 0.05). LLT was significantly associated with TBUT, MGD grade (mean 2.0 ± 0.7), and MG dropout grade (r = 0.219, P = 0.047; r = -0.221, P = 0.039; and r = 0.433, P < 0.001, respectively), although it was not related to patient symptoms. Automated noninvasive measurements using an advanced corneal topographer and LLT

  15. The influence of non-polar lipids on tear film dynamics

    KAUST Repository

    Bruna, M.

    2014-04-04

    © 2014 Cambridge University Press. In this paper we examine the effect that physiological non-polar lipids, residing on the surface of an aqueous tear film, have on the film evolution. In our model we track the evolution of the thickness of the non-polar lipid layer, the thickness of the aqueous layer and the concentration of polar lipids which reside at the interface between the two. We also utilise a force balance in the non-polar lipid layer in order to determine its velocity. We show how to obtain previous models in the literature from our model by making particular choices of the parameters. We see the formation of boundary layers in some of these submodels, across which the concentration of polar lipid and the non-polar lipid velocity and film thickness vary. We solve our model numerically for physically realistic parameter values, and we find that the evolution of the aqueous layer and the polar lipid layer are similar to that described by previous authors. However, there are interesting dynamics for the non-polar lipid layer. The effects of altering the key parameters are highlighted and discussed. In particular, we see that the Marangoni number plays a key role in determining how far over the eye the non-polar lipid spreads.

  16. Duplex Tear Film Evaporation Analysis.

    Science.gov (United States)

    Stapf, M R; Braun, R J; King-Smith, P E

    2017-12-01

    Tear film thinning, hyperosmolarity, and breakup can cause irritation and damage to the human eye, and these form an area of active investigation for dry eye syndrome research. Recent research demonstrates that deficiencies in the lipid layer may cause locally increased evaporation, inducing conditions for breakup. In this paper, we explore the conditions for tear film breakup by considering a model for tear film dynamics with two mobile fluid layers, the aqueous and lipid layers. In addition, we include the effects of osmosis, evaporation as modified by the lipid, and the polar portion of the lipid layer. We solve the system numerically for reasonable parameter values and initial conditions and analyze how shifts in these cause changes to the system's dynamics.

  17. The influence of non-polar lipids on tear film dynamics

    KAUST Repository

    Bruna, M.; Breward, C.  J.  W.

    2014-01-01

    © 2014 Cambridge University Press. In this paper we examine the effect that physiological non-polar lipids, residing on the surface of an aqueous tear film, have on the film evolution. In our model we track the evolution of the thickness of the non

  18. Evaporation-driven instability of the precorneal tear film.

    Science.gov (United States)

    Peng, Cheng-Chun; Cerretani, Colin; Braun, Richard J; Radke, C J

    2014-04-01

    Tear-film instability is widely believed to be a signature of eye health. When an interblink is prolonged, randomly distributed ruptures occur in the tear film. "Black spots" and/or "black streaks" appear in 15 to 40 s for normal individuals. For people who suffer from dry eye, tear-film breakup time (BUT) is typically less than a few seconds. To date, however, there is no satisfactory quantitative explanation for the origin of tear rupture. Recently, it was proposed that tear-film breakup is related to locally high evaporative thinning. A spatial variation in the thickness of the tear-film lipid layer (TFLL) may lead to locally elevated evaporation and subsequent tear-film breakup. We examine the local-evaporation-driven tear-film-rupture hypothesis in a one-dimensional (1-D) model for the evolution of a thin aqueous tear film overriding the cornea subject to locally elevated evaporation at its anterior surface and osmotic water influx at its posterior surface. Evaporation rate depends on mass transfer both through the coating lipid layer and through ambient air. We establish that evaporation-driven tear-film breakup can occur under normal conditions but only for higher aqueous evaporation rates. Predicted roles of environmental conditions, such as wind speed and relative humidity, on tear-film stability agree with clinical observations. More importantly, locally elevated evaporation leads to hyperosmolar spots in the tear film and, hence, vulnerability to epithelial irritation. In addition to evaporation rate, tear-film instability depends on the strength of healing flow from the neighboring region outside the breakup region, which is determined by the surface tension at the tear-film surface and by the repulsive thin-film disjoining pressure. This study provides a physically consistent and quantitative explanation for the formation of black streaks and spots in the human tear film during an interblink. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Tear film measurement by optical reflectometry technique

    Science.gov (United States)

    Lu, Hui; Wang, Michael R.; Wang, Jianhua; Shen, Meixiao

    2014-01-01

    Abstract. Evaluation of tear film is performed by an optical reflectometer system with alignment guided by a galvanometer scanner. The reflectometer system utilizes optical fibers to deliver illumination light to the tear film and collect the film reflectance as a function of wavelength. Film thickness is determined by best fitting the reflectance-wavelength curve. The spectral reflectance acquisition time is 15 ms, fast enough for detecting film thickness changes. Fast beam alignment of 1 s is achieved by the galvanometer scanner. The reflectometer was first used to evaluate artificial tear film on a model eye with and without a contact lens. The film thickness and thinning rate have been successfully quantified with the minimum measured thickness of about 0.3 μm. Tear films in human eyes, with and without a contact lens, have also been evaluated. A high-contrast spectral reflectance signal from the precontact lens tear film is clearly observed, and the thinning dynamics have been easily recorded from 3.69 to 1.31 μm with lipid layer thickness variation in the range of 41 to 67 nm. The accuracy of the measurement is better than ±0.58% of the film thickness at an estimated tear film refractive index error of ±0.001. The fiber-based reflectometer system is compact and easy to handle. PMID:24500519

  20. Expression of Lipid Peroxidation Markers in the Tear Film and Ocular Surface of Patients with Non-Sjogren Syndrome: Potential Biomarkers for Dry Eye Disease.

    Science.gov (United States)

    Choi, Won; Lian, Cui; Ying, Li; Kim, Ga Eon; You, In Cheon; Park, Soo Hyun; Yoon, Kyung Chul

    2016-09-01

    To investigate the expression of lipid peroxidation markers in the tear film and ocular surface and their correlation with disease severity in patients with dry eye disease. The concentrations of hexanoyl-lysine (HEL), 4-hydroxy-2-nonenal (HNE), and malondialdehyde (MDA) were measured with enzyme-linked immunosorbent assays in tears obtained from 44 patients with non-Sjogren syndrome dry eye and 33 control subjects. The correlations between the marker levels and the tear film and ocular surface parameters, including tear film break-up time (BUT), Schirmer tear value, tear clearance rate, keratoepitheliopathy scores, corneal sensitivity, conjunctival goblet cell density, and symptom score, were analyzed. The expression of the lipid peroxidation markers HEL, 4-HNE, and MDA in the conjunctiva was evaluated using immunohistochemistry. The concentrations of HEL, 4-HNE, and MDA were 279.84 ± 69.98 nmol/L, 0.02 ± 0.01 μg/mL, and 3.80 ± 1.05 pmol/mg in control subjects and 283.21 ± 89.67 nmol/L (p = 0.97), 0.20 ± 0.03 μg/mL (p dry eye patients. 4-HNE and MDA levels significantly correlated with BUT, Schirmer tear value, tear clearance rate, keratoepitheliopathy scores, conjunctival goblet cell density, and symptom score (p dry eye patients. The expression of late lipid peroxidation markers, 4-HNE and MDA, increases in the tear film and ocular surface of patients with dry eye. The levels correlate with various tear film and ocular surface parameters and may reflect the severity of dry eye disease.

  1. Interferometric characterization of tear film dynamics

    Science.gov (United States)

    Primeau, Brian Christopher

    The anterior refracting surface of the eye is the thin tear film that forms on the surface of the cornea. When a contact lens is on worn, the tear film covers the contact lens as it would a bare cornea, and is affected by the contact lens material properties. Tear film irregularity can cause both discomfort and vision quality degradation. Under normal conditions, the tear film is less than 10 microns thick and the thickness and topography change in the time between blinks. In order to both better understand the tear film, and to characterize how contact lenses affect tear film behavior, two interferometers were designed and built to separately measure tear film behavior in vitro and in vivo. An in vitro method of characterizing dynamic fluid layers applied to contact lenses mounted on mechanical substrates has been developed using a phase-shifting Twyman-Green interferometer. This interferometer continuously measures light reflected from the surface of the fluid layer, allowing precision analysis of the dynamic fluid layer. Movies showing this fluid layer behavior can be generated. The fluid behavior on the contact lens surface is measured, allowing quantitative analysis beyond what typical contact angle or visual inspection methods provide. The in vivo interferometer is a similar system, with additional modules included to provide capability for human testing. This tear film measurement allows analysis beyond capabilities of typical fluorescein visual inspection or videokeratometry and provides better sensitivity and resolution than shearing interferometry methods.

  2. Peripheral Neuropathy and Tear Film Dysfunction in Type 1 Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Stuti L. Misra

    2014-01-01

    Full Text Available Purpose. To compare tear film metrics in patients with type 1 diabetes mellitus (DM and healthy controls and investigate the association between peripheral neuropathy and ocular surface quality. Methods. Dry eye symptoms were quantified in 53 patients with type 1 DM and 40 age-matched controls. Ocular examination included tear film lipid layer thickness grading, tear film stability and quantity measurement, and retinal photography. DM individuals additionally underwent a detailed neuropathy assessment. Results. Neither mean age nor dry eye symptom scores differed significantly between the DM and control groups (P=0.12 and P=0.33, resp.. Tear lipid thickness (P=0.02, stability (P<0.0001, and quantity (P=0.01 were significantly lower in the DM group. Corneal sensitivity was also reduced in the DM group (P<0.001 and tear film stability was inversely associated with total neuropathy score (r=-0.29, P=0.03. Conclusion. The DM group exhibited significantly reduced tear film stability, secretion, and lipid layer quality relative to the age-matched control group. The negative correlation between tear film parameters and total neuropathy score suggests that ocular surface abnormalities occur in parallel with diabetic peripheral neuropathy.

  3. Effectiveness of Combined Tear Film Therapy in Patients with Evaporative Dry Eye with Short Tear Film Breakup Time.

    Science.gov (United States)

    Kim, Yung Hui; Kang, Yeon Soo; Lee, Hyo Seok; Choi, Won; You, In Cheon; Yoon, Kyung Chul

    2017-10-01

    The aim of this study was to evaluate the effectiveness of combined tear film therapy targeted to aqueous, mucin, and lipid layers in patients with refractory evaporative dry eye (EDE) with short tear film breakup time (TBUT). The patients who had EDE with short TBUT and severe symptoms refractory to artificial tears were treated with hyaluronic acid (HA) 0.15% and diquafosol tetrasodium (DQS) 3% (Group 1), HA and carbomer-based lipid-containing eyedrops (Liposic EDO Gel, LPO) (Group 2), or HA, DQS, and LPO (Group 3). Ocular Surface Disease Index (OSDI) score, visual analog scale (VAS) symptom score, TBUT, Schirmer score, and corneal and conjunctival staining scores were evaluated, and noninvasive tear film breakup time (NIBUT) and tear meniscus height were measured using Keratograph ® 5 M before and 1 and 3 months after treatment. OSDI scores, VAS scores, TBUT, and NIBUT were improved at 1 and 3 months after treatment in all groups (all P film layers was most effective in improving ocular symptoms and tear film quality.

  4. TFOS DEWS II Tear Film Report.

    Science.gov (United States)

    Willcox, Mark D P; Argüeso, Pablo; Georgiev, Georgi A; Holopainen, Juha M; Laurie, Gordon W; Millar, Tom J; Papas, Eric B; Rolland, Jannick P; Schmidt, Tannin A; Stahl, Ulrike; Suarez, Tatiana; Subbaraman, Lakshman N; Uçakhan, Omür Ö; Jones, Lyndon

    2017-07-01

    The members of the Tear Film Subcommittee reviewed the role of the tear film in dry eye disease (DED). The Subcommittee reviewed biophysical and biochemical aspects of tears and how these change in DED. Clinically, DED is characterized by loss of tear volume, more rapid breakup of the tear film and increased evaporation of tears from the ocular surface. The tear film is composed of many substances including lipids, proteins, mucins and electrolytes. All of these contribute to the integrity of the tear film but exactly how they interact is still an area of active research. Tear film osmolarity increases in DED. Changes to other components such as proteins and mucins can be used as biomarkers for DED. The Subcommittee recommended areas for future research to advance our understanding of the tear film and how this changes with DED. The final report was written after review by all Subcommittee members and the entire TFOS DEWS II membership. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. The ocular surface and tear film and their dysfunction in dry eye disease.

    Science.gov (United States)

    Rolando, M; Zierhut, M

    2001-03-01

    The ocular surface, tear film, lacrimal glands, and eyelids act as a functional unit to preserve the quality of the refractive surface of the eye and to resist injury and protect the eye against changing bodily and environmental conditions. Events that disturb the homeostasis of this functional unit can result in a vicious cycle of ocular surface disease. The tear film is the most dynamic structure of the functional unit, and its production and turnover is essential to maintaining the health of the ocular surface. Classically, the tear film is reported to be composed of three layers: the mucin, aqueous, and lipid layers. The boundaries and real thickness of such layers is still under discussion. A dysfunction of any of these layers can result in dry eye disease.

  6. Effect of castor oil emulsion eyedrops on tear film composition and stability.

    Science.gov (United States)

    Maïssa, Cécile; Guillon, Michel; Simmons, Peter; Vehige, Joseph

    2010-04-01

    An emulsion eyedrop containing castor oil has been shown to modify the tear film lipid layer and increase tear film stability. The primary objectives of this investigation were to measure the prevalence of castor oil in the tear fluid over time and quantify the effects on the lipid layer. A secondary objective was to quantify the initial effects on ocular symptomatology. The investigation was an open label pilot study on 5 normal and 10 dry eye subjects. A single eyedrop (Castor oil emulsion, Allergan) was instilled in each eye; the tear film appearance and composition were monitored for 4h via in vivo visualisation using the Tearscope and post in vivo tear samples analysis by HPLC. Combined results for both normal and dry eye subjects showed that castor oil was detected up to 4h after a single eyedrop instillation and associated with an increase in the level of tear film lipid. The relative amount of various lipid families was also changed. An increase in tear lipid layer thickness was significant up to one hour post-instillation for the symptomatic sub-population. The changes in tear film characteristics were associated with significantly lower symptoms up to four hours post-instillation for the symptomatic sub-population. This pilot investigation showed that castor oil eyedrops achieved a residence time of at least four hours post-instillation, producing a more stable tear film and an associated significant decrease in ocular symptoms over the entire follow-up period for the symptomatic subjects. 2009 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  7. Diet, nutraceuticals and the tear film.

    Science.gov (United States)

    Jalbert, Isabelle

    2013-12-01

    Nutrition disorders and their correlates such as obesity are increasingly prevalent worldwide. A number of studies to date have suggested numerous potential associations between diet and tear film health; this paper will provide a summary of the available literature. The tear film is characterized through its protein and lipid content and through clinical measurements of characteristics such as osmolarity, volume and stability. Malnutrition, protein and vitamin-A deficiencies are extremely deleterious to tear film health and supplementation with oral vitamin A in this setting is of clear benefit. The relative impact of diet on tear film within what would be considered normal ranges of consumption is less clear. A number of population studies have suggested that hyperlipidemia and a diet low in omega-3 fatty acids are risks factor for dry eye disease. Numerous studies have investigated the effectiveness of oral supplementation with antioxidants, omega-3 (e.g. fish oil and linseed oil) and omega-6 (e.g. evening primrose oil) fatty acids in the last 10 years. Taken together, these suggest a small benefit of oral supplementation on tear film volume, stability and decreased ocular symptoms in patients previously diagnosed with diseases involving the ocular surface (e.g. Sjögren's syndrome, meibomian gland dysfunction, dry eye disease) and contact lens wearers suffering from dry eye. More research is required to determine the exact composition, dosage and indications for their use and to fully characterize how these nutraceuticals modulate the tear film. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Effects of Systane(®) Balance on noninvasive tear film break-up time in patients with lipid-deficient dry eye.

    Science.gov (United States)

    Aguilar, Alejandro J; Marquez, Maria I; Albera, Paula A; Tredicce, Jorge L; Berra, Alejandro

    2014-01-01

    To evaluate the ability of Systane(®) Balance (SYSB) administered four times per day for 4 weeks to increase noninvasive tear film break-up time (NITFBUT) over baseline compared with a saline (SAL) control in patients with lipid-deficient dry eye (DE). Patients aged ≥18 years with DE and evidence of meibomian gland dysfunction (ie, abnormal gland expression and missing meibomian glands) were included in this randomized, parallel-group, controlled, investigator-masked comparison study. Patients were randomized to SYSB or SAL four times daily for 4 weeks. The primary efficacy variable was mean change in NITFBUT from baseline at week 4. Ocular surface staining, goblet cell density, and meibomian gland expression were also assessed. Safety assessments included adverse events (AEs), best-corrected visual acuity, and ocular signs. A total of 49 patients received study treatments (SYSB, n=25; SAL, n=24). Most patients were women (67.4%) and Caucasian (63.3%); mean ± standard deviation (SD) age was 44±19 years. DE characteristics at baseline were similar between groups. After 4 weeks of treatment, the mean ± SD NITFBUT increase from baseline was significantly greater with SYSB (2.83±0.74 seconds) compared with SAL (0.66±0.55 seconds; P<0.001, t-test). Improvements in conjunctival and corneal staining, percentage of patients with increased goblet cell density, and meibomian gland expression were also observed with 4 weeks of SYSB over SAL. No AEs were reported for either treatment group; best-corrected visual acuity and ocular signs remained stable or improved compared with baseline. SYSB restored tear film stability, improved ocular surface healing, and improved meibomian gland functionality after 4 weeks of use in patients with lipid-deficient DE. No AEs were reported with either SYSB or SAL.

  9. Effects of Systane® Balance on noninvasive tear film break-up time in patients with lipid-deficient dry eye

    Directory of Open Access Journals (Sweden)

    Aguilar AJ

    2014-11-01

    Full Text Available Alejandro J Aguilar, Maria I Marquez, Paula A Albera, Jorge L Tredicce, Alejandro Berra Universidad de Buenos Aires, Buenos Aires, Argentina Purpose: To evaluate the ability of Systane® Balance (SYSB administered four times per day for 4 weeks to increase noninvasive tear film break-up time (NITFBUT over baseline compared with a saline (SAL control in patients with lipid-deficient dry eye (DE.Patients and methods: Patients aged ≥18 years with DE and evidence of meibomian gland dysfunction (ie, abnormal gland expression and missing meibomian glands were included in this randomized, parallel-group, controlled, investigator-masked comparison study. Patients were randomized to SYSB or SAL four times daily for 4 weeks. The primary efficacy variable was mean change in NITFBUT from baseline at week 4. Ocular surface staining, goblet cell density, and meibomian gland expression were also assessed. Safety assessments included adverse events (AEs, best-corrected visual acuity, and ocular signs.Results: A total of 49 patients received study treatments (SYSB, n=25; SAL, n=24. Most patients were women (67.4% and Caucasian (63.3%; mean ± standard deviation (SD age was 44±19 years. DE characteristics at baseline were similar between groups. After 4 weeks of treatment, the mean ± SD NITFBUT increase from baseline was significantly greater with SYSB (2.83±0.74 seconds compared with SAL (0.66±0.55 seconds; P<0.001, t-test. Improvements in conjunctival and corneal staining, percentage of patients with increased goblet cell density, and meibomian gland expression were also observed with 4 weeks of SYSB over SAL. No AEs were reported for either treatment group; best-corrected visual acuity and ocular signs remained stable or improved compared with baseline.Conclusion: SYSB restored tear film stability, improved ocular surface healing, and improved meibomian gland functionality after 4 weeks of use in patients with lipid-deficient DE. No AEs were reported

  10. Tear film and ocular surface assessment in psoriasis.

    Science.gov (United States)

    Aragona, Emanuela; Rania, Laura; Postorino, Elisa Imelde; Interdonato, Alberto; Giuffrida, Roberta; Cannavò, Serafinella Patrizia; Puzzolo, Domenico; Aragona, Pasquale

    2018-03-01

    Psoriasis is a skin disease with also systemic involvement: its impact on the eye is not well established and often clinically underestimated. Aim of this study was to investigate the presence of ocular discomfort symptoms and of ocular surface changes in a population of patients with psoriasis. For this cross-sectional, comparative study, 66 patients with psoriasis were subdivided according to the presence of arthritis and to the use of biological therapy. All patients underwent clinical evaluation with the following tests: Ocular Surface Disease Index Questionnaire, Tearscope examination, meibometry, tear film breakup time, corneal and conjunctival fluorescein staining, Schirmer I test, corneal aesthesiometry, meibomian gland dysfunction (MGD) assessment and conjunctival impression cytology. 28 healthy subjects were also enrolled and treated with the same clinical tests. A statistical analysis of the results was performed. Patients with psoriasis showed a significant deterioration of the ocular surface tests, if compared with healthy subjects, demonstrated by tear film lipid layer alteration, tear film instability, corneal and conjunctival epithelial suffering and mild squamous metaplasia at impression cytology. No differences were found in ocular surface test results of the psoriatic group when patients were divided according to the presence of arthritis, whereas the anti-inflammatory treatment with biological drugs demonstrated a significant improvement of corneal stain and MGD. Our findings suggest that the ocular surface involvement in patients with psoriasis indicates the need of periodic ophthalmological examinations to diagnose the condition and allow a proper treatment, so contributing to the amelioration of patients' quality of life. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  11. Parallel definition of tear film maps on distributed-memory clusters for the support of dry eye diagnosis.

    Science.gov (United States)

    González-Domínguez, Jorge; Remeseiro, Beatriz; Martín, María J

    2017-02-01

    The analysis of the interference patterns on the tear film lipid layer is a useful clinical test to diagnose dry eye syndrome. This task can be automated with a high degree of accuracy by means of the use of tear film maps. However, the time required by the existing applications to generate them prevents a wider acceptance of this method by medical experts. Multithreading has been previously successfully employed by the authors to accelerate the tear film map definition on multicore single-node machines. In this work, we propose a hybrid message-passing and multithreading parallel approach that further accelerates the generation of tear film maps by exploiting the computational capabilities of distributed-memory systems such as multicore clusters and supercomputers. The algorithm for drawing tear film maps is parallelized using Message Passing Interface (MPI) for inter-node communications and the multithreading support available in the C++11 standard for intra-node parallelization. The original algorithm is modified to reduce the communications and increase the scalability. The hybrid method has been tested on 32 nodes of an Intel cluster (with two 12-core Haswell 2680v3 processors per node) using 50 representative images. Results show that maximum runtime is reduced from almost two minutes using the previous only-multithreaded approach to less than ten seconds using the hybrid method. The hybrid MPI/multithreaded implementation can be used by medical experts to obtain tear film maps in only a few seconds, which will significantly accelerate and facilitate the diagnosis of the dry eye syndrome. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. Coupling Fluid and Solute Dynamics Within the Ocular Surface Tear Film: A Modelling Study of Black Line Osmolarity

    KAUST Repository

    Zubkov, V. S.

    2012-07-06

    We present a mathematical model describing the spatial distribution of tear film osmolarity across the ocular surface of a human eye during one blink cycle, incorporating detailed fluid and solute dynamics. Based on the lubrication approximation, our model comprises three coupled equations tracking the depth of the aqueous layer of the tear film, the concentration of the polar lipid, and the concentration of physiological salts contained in the aqueous layer. Diffusive boundary layers in the salt concentration occur at the thinnest regions of the tear film, the black lines. Thus, despite large Peclet numbers, diffusion ameliorates osmolarity around the black lines, but nonetheless is insufficient to eliminate the build-up of solute in these regions. More generally, a heterogeneous distribution of solute concentration is predicted across the ocular surface, indicating that measurements of lower meniscus osmolarity are not globally representative, especially in the presence of dry eye. Vertical saccadic eyelid motion can reduce osmolarity at the lower black line, raising the prospect that select eyeball motions more generally can assist in alleviating tear film hyperosmolarity. Finally, our results indicate that measured evaporative rates will induce excessive hyperosmolarity at the black lines, even for the healthy eye. This suggests that further evaporative retardation at the black lines, for instance due to the cellular glycocalyx at the ocular surface or increasing concentrations of mucus, will be important for controlling hyperosmolarity as the black line thins. © 2012 Society for Mathematical Biology.

  13. Tear-Film Evaporation Rate from Simultaneous Ocular-Surface Temperature and Tear-Breakup Area.

    Science.gov (United States)

    Dursch, Thomas J; Li, Wing; Taraz, Baseem; Lin, Meng C; Radke, Clayton J

    2018-01-01

    A corneal heat-transfer model is presented to quantify simultaneous measurements of fluorescein tear-breakup area (TBA) and ocular-surface temperature (OST). By accounting for disruption of the tear-film lipid layer (TFLL), we report evaporation rates through lipid-covered tear. The modified heat-transfer model provides new insights into evaporative dry eye. A quantitative analysis is presented to assess human aqueous tear evaporation rate (TER) through intact TFLLs from simultaneous in vivo measurement of time-dependent infrared OST and fluorescein TBA. We interpret simultaneous OST and TBA measurements using an extended heat-transfer model. We hypothesize that TBAs are ineffectively insulated by the TFLL and therefore exhibit higher TER than does that for a well-insulting TFLL-covered tear. As time proceeds, TBAs increase in number and size, thereby increasing the cornea area-averaged TER and decreasing OST. Tear-breakup areas were assessed from image analysis of fluorescein tear-film-breakup video recordings and are included in the heat-transfer description of OST. Model-predicted OSTs agree well with clinical experiments. Percent reductions in TER of lipid-covered tear range from 50 to 95% of that for pure water, in good agreement with literature. The physical picture of noninsulating or ruptured TFLL spots followed by enhanced evaporation from underlying cooler tear-film ruptures is consistent with the evaporative-driven mechanism for local tear rupture. A quantitative analysis is presented of in vivo TER from simultaneous clinical measurement of transient OST and TBA. The new heat-transfer model accounts for increased TER through expanding TBAs. Tear evaporation rate varies strongly across the cornea because lipid is effectively missing over tear-rupture troughs. The result is local faster evaporation compared with nonruptured, thick lipid-covered tear. Evaporative-driven tear-film ruptures deepen to a thickness where fluorescein quenching commences and local

  14. Water-evaporation reduction by duplex films: application to the human tear film.

    Science.gov (United States)

    Cerretani, Colin F; Ho, Nghia H; Radke, C J

    2013-09-01

    Water-evaporation reduction by duplex-oil films is especially important to understand the physiology of the human tear film. Secreted lipids, called meibum, form a duplex film that coats the aqueous tear film and purportedly reduces tear evaporation. Lipid-layer deficiency is correlated with the occurrence of dry-eye disease; however, in-vitro experiments fail to show water-evaporation reduction by tear-lipid duplex films. We review the available literature on water-evaporation reduction by duplex-oil films and outline the theoretical underpinnings of spreading and evaporation kinetics that govern behavior of these systems. A dissolution-diffusion model unifies the data reported in the literature and identifies dewetting of duplex films into lenses as a key challenge to obtaining significant evaporation reduction. We develop an improved apparatus for measuring evaporation reduction by duplex-oil films including simultaneous assessment of film coverage, stability, and temperature, all under controlled external mass transfer. New data reported in this study fit into the larger body of work conducted on water-evaporation reduction by duplex-oil films. Duplex-oil films of oxidized mineral oil/mucin (MOx/BSM), human meibum (HM), and bovine meibum (BM) reduce water evaporation by a dissolution-diffusion mechanism, as confirmed by agreement between measurement and theory. The water permeability of oxidized-mineral-oil duplex films agrees with those reported in the literature, after correction for the presence of mucin. We find that duplex-oil films of bovine and human meibum at physiologic temperature reduce water evaporation only 6-8% for a 100-nm film thickness pertinent to the human tear film. Comparison to in-vivo human tear-evaporation measurements is inconclusive because evaporation from a clean-water surface is not measured and because the mass-transfer resistance is not characterized. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Post-blink tear film dynamics in healthy and dry eyes during spontaneous blinking.

    Science.gov (United States)

    Szczesna-Iskander, Dorota H

    2018-01-01

    The aim was to investigate the dynamics of post-blink tear film leveling in natural blinking conditions (NBC) for healthy subjects and those diagnosed with dry eye syndrome (DES) and to relate this phase to the tear film surface quality (TFSQ) before the following blink. The study included 19 healthy persons and 10 with dry eye, grouped according to symptoms and signs observed during examination. Lateral shearing interferometry was used to examine TFSQ. Post-blink tear film dynamics was modeled by an exponential function, characterized by the decay parameter b, and a constant, describing the level of the stabilized TFSQ. Pre-next-natural-blink TFSQ dynamics was modeled with a linear trend, described by a parameter A. The post-blink tear film dynamics reached its plateau at a significantly (P = 0.006) lower level in the normal tear film group than in the dry eye group. The median exponential decay parameter b was statistically significantly higher for the control group than for the DES group, P = 0.026. The parameter b calculated for each interblink interval was significantly correlated with the corresponding parameter A (Spearman's R = 0.35; P film fluorescein break-up time for each subject was also found (R = 0.41, P = 0.029). Significantly faster leveling of post-natural-blink tear film was observed in the group with DES than in healthy eyes. This dynamic was correlated with the pre-next-natural-blink TFSQ and tear film stability. The results of this pilot study support previous works that advocate the importance of polar lipids in the mechanism of tear film lipid spreading. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Surface Chemistry Interactions of Cationorm with Films by Human Meibum and Tear Film Compounds

    Directory of Open Access Journals (Sweden)

    Georgi As. Georgiev

    2017-07-01

    Full Text Available Cationorm® (CN cationic nanoemulsion was demonstrated to enhance tear film (TF stability in vivo possibly via effects on tear film lipid layer (TFLL. Therefore the interactions of CN with human meibum (MGS and TFLL in vitro and in vivo deserve special study. MGS and CN were spread at the air/water interface of a Langmuir surface balance to ensure a range of MGS/CN oil phase ratios: 20/1, 10/1, 5/1, 3/1, 2/1 and 1/1. The films capability to reorganize during dynamic area changes was evaluated via the surface pressure-area compression isotherms and step/relaxation dilatational rheology studies. Films structure was monitored with Brewster angle microscopy. CN/TFLL interactions at the ocular surface were monitored with non-contact specular microscopy. The in vitro studies of MGS/CN layers showed that (i CN inclusion (at fixed MGS content increased film elasticity and thickness and that (ii CN can compensate for moderate meibum deficiency in MGS/CN films. In vivo CN mixed with TFLL in a manner similar to CN/MGS interactions in vitro, and resulted in enhanced thickness of TFLL. In vitro and in vivo data complement each other and facilitated the study of the composition-structure-function relationship that determines the impact of cationic nanoemulsions on TF.

  17. Adsorption of lysozyme to phospholipid and meibomian lipid monolayer films.

    Science.gov (United States)

    Mudgil, Poonam; Torres, Margaux; Millar, Thomas J

    2006-03-15

    It is believed that a lipid layer forms the outer layer of the pre-ocular tear film and this layer helps maintain tear film stability by lowering its surface tension. Proteins of the aqueous layer of the tear film (beneath the lipid layer) may also contribute to reducing surface tension by adsorbing to, or penetrating the lipid layer. The purpose of this study was to compare the penetration of lysozyme, a tear protein, into films of meibomian lipids and phospholipids held at different surface pressures to determine if lysozyme were part of the surface layer of the tear film. Films of meibomian lipids or phospholipids were spread onto the surface of a buffered aqueous subphase. Films were compressed to particular pressures and lysozyme was injected into the subphase. Changes in surface pressure were monitored to determine adsorption or penetration of lysozyme into the surface film. Lysozyme penetrated a meibomian lipid film at all pressures tested (max=20 mN/m). It also penetrated phosphatidylglycerol, phosphatidylserine or phosphatidylethanolamine lipid films up to a pressure of 20 mN/m. It was not able to penetrate a phosphatidylcholine film at pressures >or=10 mN/m irrespective of the temperature being at 20 or 37 degrees C. However, it was able to penetrate it at very low pressures (<10 mN/m). Epifluorescence microscopy showed that the protein either adsorbs to or penetrates the lipid layer and the pattern of mixing depended upon the lipid at the surface. These results indicate that lysozyme is present at the surface of the tear film where it contributes to decreasing the surface tension by adsorbing and penetrating the meibomian lipids. Thus it helps to stabilize the tear film.

  18. Quantitative analysis of tear film fluorescence and discomfort during tear film instability and thinning.

    Science.gov (United States)

    Begley, Carolyn; Simpson, Trefford; Liu, Haixia; Salvo, Eliza; Wu, Ziwei; Bradley, Arthur; Situ, Ping

    2013-04-12

    The purpose of this study was to test the association between tear film fluorescence changes during tear break-up (TBU) or thinning and the concurrent ocular sensory response. Sixteen subjects kept one eye open as long as possible (MBI), indicated their discomfort level continuously, and rated ocular sensations of irritation, stinging, burning, pricking, and cooling using visual analog scales (VAS). Fluorescence of the tear film was quantified by a pixel-based analysis of the median pixel intensity (PI), TBU, and percentage of dark pixels (DarkPix) over time. A cutoff of 5% TBU was used to divide subjects into either break-up (BU) or minimal break-up (BUmin) groups. Tear film fluorescence decreased (median PI) and the percentage of TBU and DarkPix increased in all trials, with the rate significantly greater in the BU than the BUmin group (Mann-Whitney U test, P film thinning best explains decreasing tear film fluorescence during trials. This was highly correlated with increasing ocular discomfort, suggesting that both tear film thinning and TBU stimulate underlying corneal nerves, although TBU produced more rapid stimulation. Slow increases in tear film hyperosmolarity may cause the gradual increase in discomfort during slow tear film thinning, whereas the sharp increases in discomfort during TBU suggest a more complex stimulus.

  19. [A study on the diagnostic value of tear film objective scatter index in dry eye].

    Science.gov (United States)

    Su, Y D; Liang, Q F; Wang, N L; Antoine, Labbè

    2017-09-11

    Objective: To study the sensitivity and specificity of tear film objective scatter index to the diagnosis dry eye disease (DED). Methods: A prospective case-controlled study. Fifty-three patients with DED and 32 healthy age- and sex-matched control subjects were included from July to October 2016. All subjects underwent the examinations sequentially as follows: evaluation of ocular surface disease symptoms using the Ocular Surface Disease Index, optical quality detection, lipid layer thickness, tear film breakup time and SchirmerⅠtest. With Optical Quality Analysis SystemⅡ, the values of modulation transfer function cut off, basic objective scatter index (OSI) and total OSI were measured. To eliminate the influence of other refractive media, the tear film OSI (TF-OSI) was calculated, and the difference in TF-OSI between two groups was analyzed with the independent-samples t test. Spearman's correlation analysis was used to detect the correlation of each parameter in the DED group. With the receiver operating characteristic curve and the area under the curve (AUC), the specificity and sensitivity of TF-OSI and other parameters were described to differentiate DED from normal eyes. Results: In the dry eye group, the value of modulation transfer function cut off (32.07±11.95) was significantly lower than the normal group (39.38±9.44, t=- 3.096, P= 0.003) , and the mean value and dispersion of TF-OSI (0.50±0.43, 0.52±0.81) were higher than the normal group (0.21±0.16, 0.12±0.01) ( t= 4.300, P= 0.000, t= 3.546, P= 0.001) . The mean value of TF-OSI had a positive correlation with lipid layer thickness ( r= 0.365, P= 0.007) and dispersion of TF-OSI ( r= 0.581, P= 0.000), and a negative correlation with MTF cut off ( r=- 0.368, P= 0.007). To the diagnostic value of DED, the mean value of TF-OSI had a sensitivity of 0.736, a specificity of 0.762, and the AUC was 0.764. The dispersion of TF-OSI had a sensitivity of 0.811 and a specificity of 0.810, and the AUC was 0

  20. Meniscal Tear Film Fluid Dynamics Near Marx’s Line

    KAUST Repository

    Zubkov, V. S.; Breward, C. J. W.; Gaffney, E. A.

    2013-01-01

    meniscus. However, resolving tear film behaviour within the meniscus and especially its apices is required to characterise the flow dynamics where the tear film is especially thin, and thus most susceptible to evaporatively induced hyperosmolarity

  1. Lipid composition of human meibum

    Directory of Open Access Journals (Sweden)

    R. Schnetler

    2013-12-01

    Full Text Available The structure and function of meibomian gland lipids in the tear film are highly complex. Evidence shows that the precorneal tear film consists of discrete layers: the inner mucin layer, the middle aqueous layer and the outer lipid layer. In this review we focus on the outer, biphasic lipid layer of the tear film which consists of a ‘thick’ outer, non-polar layer  and a ‘thin’ inner, polar layer. We discuss the main composition of the polar and non-polar lipids within meibum (wax esters, cholesteryl esters, mono-, di- and tri-acylglycerols, ceramides, phospholipids  et cetera. We address the composition of meibomian lipids in subjects suffering from various ocular diseases in comparison with the composition in healthy individuals. Further analysis is needed to determine whether a correlation exists between the etiology of various ocular diseases and the fluctuation on the lipids as well as to establish whether or not tear lipid analysis can be used as a diagnostic tool.

  2. A Controlled Study on the Correlation between Tear Film Volume and Tear Film Stability in Diabetic Patients.

    Science.gov (United States)

    Eissa, Iman M; Khalil, Noha M; El-Gendy, Heba A

    2016-01-01

    Purpose. To assess the tear film quantity and correlate it with the quality and stability of the tear film in diabetics and compare them to age matched controls. Introduction. Diabetes affects tear film parameters in multiple ways. Poor metabolic control and neuropathy are postulated factors. To further understand how diabetes affects tear film parameters this study was conducted. Subjects and Methods. Tear meniscus height was measured by anterior segment OCT, along with tear thinning time, a subtype of noninvasive tear break-up time, and blinking rate per minute which were all recorded for 22 diabetic patients. Correlations between these tear film parameters were studied and then compared to 16 age matched controls. Results. A statistically significant difference was found in blinking rate between the diabetic and the control group (P = 0.002), with higher blinking rate among diabetics. All tear film parameters were negatively correlated with duration of diabetes. A positive correlation was found between tear film volume and stability. Conclusion. Diabetes affects the tear film in various ways. Diabetics should be examined for dry eye signs even in absence of symptoms which may be masked by associated neuropathy. Duration of diabetes has an impact on tear film status.

  3. A Controlled Study on the Correlation between Tear Film Volume and Tear Film Stability in Diabetic Patients

    Directory of Open Access Journals (Sweden)

    Iman M. Eissa

    2016-01-01

    Full Text Available Purpose. To assess the tear film quantity and correlate it with the quality and stability of the tear film in diabetics and compare them to age matched controls. Introduction. Diabetes affects tear film parameters in multiple ways. Poor metabolic control and neuropathy are postulated factors. To further understand how diabetes affects tear film parameters this study was conducted. Subjects and Methods. Tear meniscus height was measured by anterior segment OCT, along with tear thinning time, a subtype of noninvasive tear break-up time, and blinking rate per minute which were all recorded for 22 diabetic patients. Correlations between these tear film parameters were studied and then compared to 16 age matched controls. Results. A statistically significant difference was found in blinking rate between the diabetic and the control group (P=0.002, with higher blinking rate among diabetics. All tear film parameters were negatively correlated with duration of diabetes. A positive correlation was found between tear film volume and stability. Conclusion. Diabetes affects the tear film in various ways. Diabetics should be examined for dry eye signs even in absence of symptoms which may be masked by associated neuropathy. Duration of diabetes has an impact on tear film status.

  4. Effects of tear film dynamics on quality of vision.

    Science.gov (United States)

    Koh, Shizuka; Tung, Cynthia I; Inoue, Yasushi; Jhanji, Vishal

    2018-06-15

    The precorneal tear film is maintained by blinking and exhibits different phases in the tear cycle. The tear film serves as the most anterior surface of the eye and plays an important role as a first refractive component of the eye. Alterations in tear film dynamics may cause both vision-related and ocular surface-related symptoms. Although the optical quality associated with the tear film dynamics previously received little attention, objective measurements of optical quality using wavefront sensors have enabled us to quantify optical aberrations induced by the tear film. This has provided an objective method for assessing reduced optical quality in dry eye; thus, visual disturbances were included in the definition of dry eye disease in the 2007 Dry Eye Workshop report. In addition, sequential measurements of wavefront aberrations have provided us with valuable insights into the dynamic optical changes associated with tear film dynamics. This review will focus on the current knowledge of the mechanisms of wavefront variations that are caused by different aspects of tear film dynamics: specifically, quality, quantity and properties of the tear film, demonstrating the respective effects of dry eye, epiphora and instillation of eye drops on the quality of vision. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  5. Changes of tear film after trabeculectomy in glaucoma

    Directory of Open Access Journals (Sweden)

    Xue-Jun Li

    2015-07-01

    Full Text Available AIM: To learn the changes of the tear film before and after the trabeculectomy of glaucoma and explore the incidence of dry eye and the prevention and control measures.METHODS: The 36 patients(60 eyesof glaucoma were examined in detail before 3d of trabeculectomy and after the surgery at 3, 7, 14 and 30d. The examinations include lower eyelid central river of tears, break-up time(BUT, Schirmer Ⅰ test(SⅠtand staining scores of corneal fluorescein under slit lamp microscope.RESULTS:The tear meniscus height of central lower eyelid was increased and the tear film BUT was shortened at the same time, the scores of SⅠt was reduced and corneal fluorescein staining score was increased at postoperative 3 and 7d compared with that of preoperation. The tear meniscus height of central lower eyelid, tear film BUT and SIt and score of corneal fluorescein staining began to recover in most of the affected eyes after surgery 14d. At 30d after surgery, 22% of patients tear film failed to recover to the preoperative level; dry eye occured in 18% preoperative eyes with normal tear film.CONCLUSION:Trabeculectomy of glaucoma may affect the stability of the tear film and some patients showeing obvious dry eye and should be intervened and treatmented timely.

  6. On tear film breakup (TBU): dynamics and imaging.

    Science.gov (United States)

    Braun, Richard J; Driscoll, Tobin A; Begley, Carolyn G; King-Smith, P Ewen; Siddique, Javed I

    2018-06-13

    We report the results of some recent experiments to visualize tear film dynamics. We then study a mathematical model for tear film thinning and tear film breakup (TBU), a term from the ocular surface literature. The thinning is driven by an imposed tear film thinning rate which is input from in vivo measurements. Solutes representing osmolarity and fluorescein are included in the model. Osmolarity causes osmosis from the model ocular surface, and the fluorescein is used to compute the intensity corresponding closely to in vivo observations. The imposed thinning can be either one-dimensional or axisymmetric, leading to streaks or spots of TBU, respectively. For a spatially-uniform (flat) film, osmosis would cease thinning and balance mass lost due to evaporation; for these space-dependent evaporation profiles TBU does occur because osmolarity diffuses out of the TBU into the surrounding tear film, in agreement with previous results. The intensity pattern predicted based on the fluorescein concentration is compared with the computed thickness profiles; this comparison is important for interpreting in vivo observations. The non-dimensionalization introduced leads to insight about the relative importance of the competing processes; it leads to a classification of large vs small TBU regions in which different physical effects are dominant. Many regions of TBU may be considered small, revealing that the flow inside the film has an appreciable influence on fluorescence imaging of the tear film.

  7. Comparison of non-invasive tear film stability measurement techniques.

    Science.gov (United States)

    Wang, Michael Tm; Murphy, Paul J; Blades, Kenneth J; Craig, Jennifer P

    2018-01-01

    Measurement of tear film stability is commonly used to give an indication of tear film quality but a number of non-invasive techniques exists within the clinical setting. This study sought to compare three non-invasive tear film stability measurement techniques: instrument-mounted wide-field white light clinical interferometry, instrument-mounted keratoscopy and hand-held keratoscopy. Twenty-two subjects were recruited in a prospective, randomised, masked, cross-over study. Tear film break-up or thinning time was measured non-invasively by independent experienced examiners, with each of the three devices, in a randomised order, within an hour. Significant correlation was observed between instrument-mounted interferometric and keratoscopic measurements (p 0.05). Tear film stability values obtained from the hand-held device were significantly shorter and demonstrated narrower spread than the other two instruments (all p 0.05). Good clinical agreement exists between the instrument-mounted interferometric and keratoscopic measurements but not between the hand-held device and either of the instrument-mounted techniques. The results highlight the importance of specifying the instrument employed to record non-invasive tear film stability. © 2017 Optometry Australia.

  8. Meniscal Tear Film Fluid Dynamics Near Marx’s Line

    KAUST Repository

    Zubkov, V. S.

    2013-07-03

    Extensive studies have explored the dynamics of the ocular surface fluid, though theoretical investigations are typically limited to the use of the lubrication approximation, which is not guaranteed to be uniformly valid a-priori throughout the tear meniscus. However, resolving tear film behaviour within the meniscus and especially its apices is required to characterise the flow dynamics where the tear film is especially thin, and thus most susceptible to evaporatively induced hyperosmolarity and subsequent epithelial damage. Hence, we have explored the accuracy of the standard lubrication approximation for the tear film by explicit comparisons with the 2D Navier-Stokes model, considering both stationary and moving eyelids. Our results demonstrate that the lubrication model is qualitatively accurate except in the vicinity of the eyelids. In particular, and in contrast to lubrication theory, the solution of the full Navier-Stokes equations predict a distinct absence of fluid flow, and thus convective mixing in the region adjacent to the tear film contact line. These observations not only support emergent hypotheses concerning the formation of Marx\\'s line, a region of epithelial cell staining adjacent to the contact line on the eyelid, but also enhance our understanding of the pathophysiological consequences of the flow profile near the tear film contact line. © 2013 Society for Mathematical Biology.

  9. Tear film proteome in age-related macular degeneration.

    Science.gov (United States)

    Winiarczyk, Mateusz; Kaarniranta, Kai; Winiarczyk, Stanisław; Adaszek, Łukasz; Winiarczyk, Dagmara; Mackiewicz, Jerzy

    2018-06-01

    Age-related macular degeneration (AMD) is the main reason for blindness in elderly people in the developed countries. Current screening protocols have limitations in detecting the early signs of retinal degeneration. Therefore, it would be desirable to find novel biomarkers for early detection of AMD. Development of novel biomarkers would help in the prevention, diagnostics, and treatment of AMD. Proteomic analysis of tear film has shown promise in this research area. If an optimal set of biomarkers could be obtained from accessible body fluids, it would represent a reliable way to monitor disease progression and response to novel therapies. Tear films were collected on Schirmer strips from a total of 22 patients (8 with wet AMD, 6 with dry AMD, and 8 control individuals). 2D electrophoresis was used to separate tear film proteins prior to their identification with matrix-assisted laser desorption/ionization time of flight spectrometer (MALDI-TOF/TOF) and matching with functional databases. A total of 342 proteins were identified. Most of them were previously described in various proteomic studies concerning AMD. Shootin-1, histatin-3, fidgetin-like protein 1, SRC kinase signaling inhibitor, Graves disease carrier protein, actin cytoplasmic 1, prolactin-inducible protein 1, and protein S100-A7A were upregulated in the tear film samples isolated from AMD patients and were not previously linked with this disease in any proteomic analysis. The upregulated proteins supplement our current knowledge of AMD pathogenesis, providing evidence that certain specific proteins are expressed into the tear film in AMD. As far we are aware, this is the first study to have undertaken a comprehensive in-depth analysis of the human tear film proteome in AMD patients.

  10. Modelling the evaporation of a tear film over a contact lens.

    Science.gov (United States)

    Talbott, Kevin; Xu, Amber; Anderson, Daniel M; Seshaiyer, Padmanabhan

    2015-06-01

    A contact lens (CL) separates the tear film into a pre-lens tear film (PrLTF), the fluid layer between the CL and the outside environment, and a post-lens tear film (PoLTF), the fluid layer between the CL and the cornea. We examine a model for evaporation of a PrLTF on a modern permeable CL allowing fluid transfer between the PrLTF and the PoLTF. Evaporation depletes the PrLTF, and continued evaporation causes depletion of the PoLTF via fluid loss through the CL. Governing equations include Navier-Stokes, heat and Darcy's equations for the fluid flow and heat transfer in the PrLTF and porous layer. The PoLTF is modelled by a fixed pressure condition on the posterior surface of the CL. The original model is simplified using lubrication theory for the PrLTF and CL applied to a sagittal plane through the eye. We obtain a partial differential equation (PDE) for the PrLTF thickness that is first-order in time and fourth-order in space. This model incorporates evaporation, conjoining pressure effects in the PrLTF, capillarity and heat transfer. For a planar film, we find that this PDE can be reduced to an ordinary differential equation (ODE) that can be solved analytically or numerically. This reduced model allows for interpretation of the various system parameters and captures most of the basic physics contained in the model. Comparisons of ODE and PDE models, including estimates for the loss of fluid through the lens due to evaporation, are given. © The Authors 2014. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  11. Impact of environmental adaptation on tear film assessments.

    Science.gov (United States)

    Fagehi, R

    2018-03-01

    The purpose of this study was to investigate the effect of ocular environmental adaptation on clinical tear film assessment. Thirty subjects (male, mean age 23±2.5) participated in this study. A number of clinical tear film tests were applied, including: fluorescein tear break-up time (FTBUT), Schirmer test and tear prism height test (TPH). The tear physiology of each subject was evaluated twice, once immediately when they arrived from the external environment, and then after 30minutes adaptation in the exam room environment. The mean values were: Schirmer test A (22.1±2.99), Schirmer test B (24.2±2.63), FTBUT A (8.00±1.94), FTBUT B (9.13±2.04), TPH A (0.179±0.026) and TPH B* (0.187±0.023). Statistical testing using Wilcoxon-signed rank test showed a significant difference between the Schirmer test results measured at the different times (P=0.008). Also, the FTBUT and tear prism height test results showed significant differences between the two evaluation times, (P=0.001, 0.011, respectively) (A: tear assessed when the subject comes from the outside environment, B: tear film assessed after 30min adaptation in the clinical environment). This study showed a significant difference between the tear film test results evaluated when the subjects were assessed immediately from the outside environment and after an adaptation time in the clinic environment. Practitioners must consider the effect of differences between external and clinical environment adaptation on clinical tear film physiology. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  12. Evaluation of the tear film stability after laser in situ keratomileusis using the tear film stability analysis system.

    Science.gov (United States)

    Goto, Tomoko; Zheng, Xiaodong; Klyce, Stephen D; Kataoka, Hisashi; Uno, Toshihiko; Yamaguchi, Masahiko; Karon, Mike; Hirano, Sumie; Okamoto, Shigeki; Ohashi, Yuichi

    2004-01-01

    To evaluate the tear film stability of patients before and after laser in situ keratomileusis (LASIK) using the tear film stability analysis system (TSAS). Prospective observational case series. New videokeratography software for a topographic modeling system (TMS-2N) was developed that can automatically capture consecutive corneal surface images every second for 10 seconds. Thirty-four subjects (64 eyes) who underwent myopia LASIK were enrolled in this study. All subjects were examined with the new system before LASIK and at 1 week, 1 month, 3 months, and 6 months after the surgery. Corneal topographs were analyzed for tear breakup time (TMS breakup time) and breakup area (TMS breakup area). Based on pre-LASIK TSAS analysis, subjects were separated into normal and abnormal TSAS value groups. The criteria for the normal group were either TMS breakup time more than 5 seconds or TMS breakup area less than 0.2. The percentage of the occurrence of superficial punctuate keratitis was compared between the two groups with regard to subject's dry eye signs and symptoms. Tear film stability decreased significantly during the early period after LASIK, as indexed by decreased TMS breakup time and increased TMS breakup area. Tear film instability resolved at 6 months after surgery. Before LASIK, 22 subjects (43 eyes) had normal TSAS evaluation and 12 subjects (21 eyes) were abnormal. After LASIK, among normal TSAS value eyes, 8 of 43 (18.6%) eyes developed superficial punctuate keratitis. In sharp contrast, 14 of 21 (66.7%) eyes in the abnormal group displayed superficial punctuate keratitis, correlating well with the patients' dry eye symptoms. The difference in the presence of superficial punctuate keratitis after LASIK between normal and abnormal TSAS value groups was statistically significant (P <.001). Subjects with abnormal TSAS evaluation also displayed resistance to dry eye treatment and had extended period of recovery. Tear film stability analysis can be a useful

  13. The effect of Meibomian lipids and tear proteins on evaporation rate under controlled in vitro conditions.

    Science.gov (United States)

    Herok, George Henryk; Mudgil, Poonam; Millar, Thomas James

    2009-07-01

    The lipid layer of the tear film is associated with preventing evaporative loss. The ability of human Meibomian lipids to reduce evaporation in vitro was tested. Films of human or animal Meibomian lipids or mixtures of cholesterol and phosphatidylcholine were spread on the surface of either artificial buffer or on whole tears and placed on a mass balance that was enclosed in a sealed chamber. The temperature was adjusted to 37 degrees C and gas flow was controlled. Increasing the amounts of Meibomian lipids gave a very small reduction in evaporation. It was concluded from these in vitro experiments that prevention of evaporation from the tear film is not due to the Meibomian lipids alone, but is more likely to be due to a complex interaction between components of the aqueous and the Meibomian lipids.

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

    Science.gov (United States)

    Garrigue, Jean-Sébastien; Amrane, Mourad; Faure, Marie-Odile; Holopainen, Juha M; Tong, Louis

    2017-11-01

    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.

  15. Surfactant properties of human meibomian lipids.

    Science.gov (United States)

    Mudgil, Poonam; Millar, Thomas J

    2011-03-25

    Human meibomian lipids are the major part of the lipid layer of the tear film. Their surfactant properties enable their spread across the aqueous layer and help maintain a stable tear film. The purpose of this study was to investigate surfactant properties of human meibomian lipids in vitro and to determine effects of different physical conditions such as temperature and increased osmolarity, such as occur in dry eye, on these properties. Human meibomian lipids were spread on an artificial tear solution in a Langmuir trough. The lipid films were compressed and expanded to record the surface pressure-area (Π-A) isocycles. The isocycles were recorded under different physical conditions such as high pressure, increasing concentration and size of divalent cations, increasing osmolarity, and varying temperature. Π-A isocycles of meibomian lipids showed that they form liquid films that are compressible and multilayered. The isocycles were unaffected by increasing concentration or size of divalent cations and increasing osmolarity in the subphase. Temperature had a marked effect on the lipids. Increase in temperature caused lipid films to become fluid, an expected feature, but decrease in temperature unexpectedly caused expansion of lipids and an increase in pressure suggesting enhanced surfactant properties. Human meibomian lipids form highly compressible, non-collapsible, multilayered liquid films. These lipids have surfactants that allow them to spread across an aqueous subphase. Their surfactant properties are unaffected by increasing divalent cations or hyperosmolarity but are sensitive to temperature. Cooling of meibomian lipids enhances their surfactant properties.

  16. Transient Tear Film Dysfunction after Cataract Surgery in Diabetic Patients.

    Directory of Open Access Journals (Sweden)

    Donghong Jiang

    Full Text Available Diabetes mellitus is an increasingly common systemic disease. Many diabetic patients seek cataract surgery for a better visual acuity. Unlike in the general population, the influence of cataract surgery on tear film function in diabetic patients remains elusive. The aim of this study was to evaluate the tear function in diabetic and nondiabetic patients following cataract surgery.In this prospective, interventional case series, 174 diabetic patients without dry eye syndrome (DES and 474 age-matched nondiabetic patients as control who underwent phacoemulsification were enrolled at two different eye centers between January 2011 and January 2013. Patients were followed up at baseline and at 7 days, 1 month, and 3 months postoperatively. Ocular symptom scores (Ocular Surface Disease Index, OSDI and tear film function including tear film stability (tear film break-up time, TBUT, corneal epithelium integrity (corneal fluorescein staining, CFS, and tear secretion (Schirmer's I test, SIT were evaluated.In total, 83.9% of the diabetic patients (146 cases with 185 eyes and 89.0% of the nondiabetic patients (422 cases with 463 eyes completed all check-ups after the interventions (P = 0.095. The incidence of DES was 17.1% in the diabetic patients and 8.1% in the nondiabetic patients at 7 days after cataract surgery. In the diabetic patients, the incidence of DES remained 4.8% at 1 month postoperatively and decreased to zero at 3 months after surgery. No DES was diagnosed in nondiabetic patients at either the 1-month or 3-month follow-up. Compared with the baseline, the diabetic patients had worse symptom scores and lower TBUT values at 7 days and 1 month but not at 3 months postoperatively. In the nondiabetic patients, symptom scores and TBUT values had returned to preoperative levels at 1-month check-up. CFS scores and SIT values did not change significantly postoperatively in either group (P = 0.916 and P = 0.964, respectively.Diabetic patients undergoing

  17. Interferometer for measuring the dynamic surface topography of a human tear film

    Science.gov (United States)

    Primeau, Brian C.; Greivenkamp, John E.

    2012-03-01

    The anterior refracting surface of the eye is the thin tear film that forms on the surface of the cornea. Following a blink, the tear film quickly smoothes and starts to become irregular after 10 seconds. This irregularity can affect comfort and vision quality. An in vivo method of characterizing dynamic tear films has been designed based upon a near-infrared phase-shifting interferometer. This interferometer continuously measures light reflected from the tear film, allowing sub-micron analysis of the dynamic surface topography. Movies showing the tear film behavior can be generated along with quantitative metrics describing changes in the tear film surface. This tear film measurement allows analysis beyond capabilities of typical fluorescein visual inspection or corneal topography and provides better sensitivity and resolution than shearing interferometry methods. The interferometer design is capable of identifying features in the tear film much less than a micron in height with a spatial resolution of about ten microns over a 6 mm diameter. This paper presents the design of the tear film interferometer along with the considerations that must be taken when designing an interferometer for on-eye diagnostics. Discussions include eye movement, design of null optics for a range of ocular geometries, and laser emission limits for on-eye interferometry.

  18. A new method for tear film stability analysis using videokeratography.

    Science.gov (United States)

    Goto, Tomoko; Zheng, Xiaodong; Klyce, Stephen D; Kataoka, Hisashi; Uno, Toshihiko; Karon, Mike; Tatematsu, Yoshiyuki; Bessyo, Takeo; Tsubota, Kazuo; Ohashi, Yuichi

    2003-05-01

    To report a new tear film stability analysis system using videokeratography. Observational case series. New videokeratography software for TMS-2N (topographic modeling system; TOMEY Corporation, Nagoya, Japan) was developed that can automatically capture consecutive corneal surface images every second for 10 seconds. Forty-eight adult volunteers (80 eyes) were recruited for this study, and all subjects were examined with the new system. Corneal topographs were analyzed for tear breakup time (TMS-BUT) and the ratio of breakup area to entire color-code area (TMS-BUA) was calculated. Routine methods for tear film breakup time evaluation using slit-lamp microscope and fluorescence staining (SLE-BUT) were performed for comparison purposes. Regressive correlations of TMS-BUT or TMS-BUA with SLE-BUT were analyzed. Based on SLE results, subjects were separated into two groups with normal and short BUT, respectively. TMS-BUT and TMS-BUA were compared with SLE-BUT data with regard to the sensitivity and specificity of evaluation of dry eye symptoms. Topographic modeling system-tear breakup time (TMS-BUT) had a positive correlation with SLE-BUT (R = 0.7219, P TMS-BUA showed a negative correlation (R = 0.6317, P TMS-BUT, 9 (81.82%) of which were associated with dry eye symptoms. The sensitivities of TMS-BUT and TMS-BUA were 97.5% and 95%, respectively, significantly higher than that of SLE-BUT (75%), with P =.008 and 0.01, respectively. Topographic modeling system-BUT and TMS-BUA displayed a similar rate of specificity in comparison with SLE-BUT. This new videokeratography system is a noninvasive and objective method with increased sensitivity for tear film stability analysis.

  19. Goldmann tonometry tear film error and partial correction with a shaped applanation surface.

    Science.gov (United States)

    McCafferty, Sean J; Enikov, Eniko T; Schwiegerling, Jim; Ashley, Sean M

    2018-01-01

    The aim of the study was to quantify the isolated tear film adhesion error in a Goldmann applanation tonometer (GAT) prism and in a correcting applanation tonometry surface (CATS) prism. The separation force of a tonometer prism adhered by a tear film to a simulated cornea was measured to quantify an isolated tear film adhesion force. Acrylic hemispheres (7.8 mm radius) used as corneas were lathed over the apical 3.06 mm diameter to simulate full applanation contact with the prism surface for both GAT and CATS prisms. Tear film separation measurements were completed with both an artificial tear and fluorescein solutions as a fluid bridge. The applanation mire thicknesses were measured and correlated with the tear film separation measurements. Human cadaver eyes were used to validate simulated cornea tear film separation measurement differences between the GAT and CATS prisms. The CATS prism tear film adhesion error (2.74±0.21 mmHg) was significantly less than the GAT prism (4.57±0.18 mmHg, p film adhesion error was independent of applanation mire thickness ( R 2 =0.09, p =0.04). Fluorescein produces more tear film error than artificial tears (+0.51±0.04 mmHg; p film adhesion error (1.40±0.51 mmHg) was significantly less than that of the GAT prism (3.30±0.38 mmHg; p =0.002). Measured GAT tear film adhesion error is more than previously predicted. A CATS prism significantly reduced tear film adhesion error bŷ41%. Fluorescein solution increases the tear film adhesion compared to artificial tears, while mire thickness has a negligible effect.

  20. Goldmann tonometry tear film error and partial correction with a shaped applanation surface

    Directory of Open Access Journals (Sweden)

    McCafferty SJ

    2018-01-01

    Full Text Available Sean J McCafferty,1–4 Eniko T Enikov,5 Jim Schwiegerling,2,3 Sean M Ashley1,3 1Intuor Technologies, 2Department of Ophthalmology, University of Arizona College of Medicine, 3University of Arizona College of Optical Science, 4Arizona Eye Consultants, 5Department of Mechanical and Aerospace, University of Arizona College of Engineering, Tucson, AZ, USA Purpose: The aim of the study was to quantify the isolated tear film adhesion error in a Goldmann applanation tonometer (GAT prism and in a correcting applanation tonometry surface (CATS prism.Methods: The separation force of a tonometer prism adhered by a tear film to a simulated cornea was measured to quantify an isolated tear film adhesion force. Acrylic hemispheres (7.8 mm radius used as corneas were lathed over the apical 3.06 mm diameter to simulate full applanation contact with the prism surface for both GAT and CATS prisms. Tear film separation measurements were completed with both an artificial tear and fluorescein solutions as a fluid bridge. The applanation mire thicknesses were measured and correlated with the tear film separation measurements. Human cadaver eyes were used to validate simulated cornea tear film separation measurement differences between the GAT and CATS prisms.Results: The CATS prism tear film adhesion error (2.74±0.21 mmHg was significantly less than the GAT prism (4.57±0.18 mmHg, p<0.001. Tear film adhesion error was independent of applanation mire thickness (R2=0.09, p=0.04. Fluorescein produces more tear film error than artificial tears (+0.51±0.04 mmHg; p<0.001. Cadaver eye validation indicated the CATS prism’s tear film adhesion error (1.40±0.51 mmHg was significantly less than that of the GAT prism (3.30±0.38 mmHg; p=0.002.Conclusion: Measured GAT tear film adhesion error is more than previously predicted. A CATS prism significantly reduced tear film adhesion error by ~41%. Fluorescein solution increases the tear film adhesion compared to

  1. Dynamic measurement of the corneal tear film with a Twyman-Green interferometer

    Science.gov (United States)

    Micali, Jason D.; Greivenkamp, John E.; Primeau, Brian C.

    2015-05-01

    An interferometer for measuring dynamic properties of the in vivo tear film on the human cornea has been developed. The system is a near-infrared instantaneous phase-shifting Twyman-Green interferometer. The laser source is a 785 nm solid-state laser, and the system has been carefully designed and calibrated to ensure that the system operates at eye-safe levels. Measurements are made over a 6 mm diameter on the cornea. Successive frames of interferometric height measurements are combined to produce movies showing both the quantitative and qualitative changes in the topography of the tear film surface and structure. To date, measurement periods of up to 120 s at 28.6 frames per second have been obtained. Several human subjects have been examined using this system, demonstrating a surface height resolution of 25 nm and spatial resolution of 6 μm. Examples of features that have been observed in these preliminary studies of the tear film include postblink disruption, evolution, and stabilization of the tear film; tear film artifacts generated by blinking; tear film evaporation and breakup; and the propagation of foreign objects in the tear film. This paper discusses the interferometer design and presents results from in vivo measurements.

  2. Non-invasive pre-lens tear film assessment with high-speed videokeratoscopy.

    Science.gov (United States)

    Llorens-Quintana, Clara; Mousavi, Maryam; Szczesna-Iskander, Dorota; Iskander, D Robert

    2018-02-01

    To evaluate the effect of two types of daily contact lenses (delefilcon A and omafilcon A) on the tear film and establish whether it is dependent on pre-corneal tear film characteristics using a new method to analyse high-speed videokeratoscopy recordings, as well as to determine the sensitivity of the method in differentiating between contact lens materials on eye. High-speed videokeratoscopy recordings were analysed using a custom made automated algorithm based on a fractal dimension approach that provides a set of parameters directly related to tear film stability. Fifty-four subjects participated in the study. Baseline measurements, in suppressed and natural blinking conditions, were taken before subjects were fitted with two different daily contact lenses and after four hours of contact lens wear. The method for analysing the stability of the tear film provides alternative parameters to the non-invasive break up time to assess the quality of the pre-corneal and pre-lens tear film. Both contact lenses significantly decreased the quality of the tear film in suppressed and natural blinking conditions (pfilm characteristics were not correlated with the decrease in pre-lens tear film quality. High-speed videokeratoscopy equipped with an automated method to analyse the dynamics of the tear film is able to distinguish between contact lens materials in vivo. Incorporating the assessment of pre-lens tear film to the clinical practice could aid improving contact lens fitting and understand contact lens comfort. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  3. Tear Film Break-Up Time: Comparison between Patients using Psychiatric Drugs and Healthy Individuals

    Directory of Open Access Journals (Sweden)

    Parvin Dibajnia

    2014-09-01

    Full Text Available Background: Ocular dryness is a well-recognized adverse side effect of many medications. The purpose of this study was to compare tear film stability between psychiatric patients that use lithium carbonate or carbamazepine and normal cases. Materials and Methods: Tear film break up time test was performed in three groups, 30 patients using lithium carbonate, 30 patients using carbamazepine and 30 normal cases. Values of the TBUTs were compared among groups by the independent t-test. Results: Differences between both of patients and control groups were significant (p<0.0001. Conclusion: The results show that these drugs contribute to decrease of tear film break up time.

  4. Application of texture analysis in tear film surface assessment based on videokeratoscopy

    Directory of Open Access Journals (Sweden)

    David Alonso-Caneiro

    2013-10-01

    Conclusions: Texture analysis of videokeratoscopy images is applicable to study tear film anomalies in dry eye subjects. The proposed technique appears to have demonstrated its clinical relevance and utility.

  5. The importance of the precorneal tear film for the quality of optical imaging.

    OpenAIRE

    Rieger, G

    1992-01-01

    The optical function of the eye critically depends on the presence of an intact precorneal tear film. Abnormalities of the tear film such as those occurring in the dry eye syndrome or in otherwise irritated eyes may interfere with vision. In 30 patients with dry eyes artificial tears were found to produce statistically significant improvement of vision (p less than 0.001) while no significant changes were seen in the untreated partner eyes. Static perimetry in another 30 patients using the 'm...

  6. Do Lipids Retard the Evaporation of the Tear Fluid?

    DEFF Research Database (Denmark)

    Rantamaki, A. H.; Javanainen, M.; Vattulainen, I.

    2012-01-01

    phosphatidylcholine (PC), nonpolar cholesteryl ester, triglycerides, and wax ester (WE). Brewster angle microscopy (BAM) and interfacial shear rheometry (ISR) were used to assess the lateral structure and shear stress response of the lipid layers, respectively. RESULTS. Olive oil and long-chain alcohol decreased......PURPOSE. We examined in vitro the potential evaporation-retarding effect of the tear film lipid layer (TFLL). The artificial TFLL compositions used here were based on the present knowledge of TFLL composition. METHODS. A custom-built system was developed to measure evaporation rates at 35 degrees C....... Lipids were applied to an air-water interface, and the evaporation rate through the lipid layer was defined as water loss from the interface. A thick layer of olive oil and a monolayer of long-chain alcohol were used as controls. The artificial TFLLs were composed of 1 to 4 lipid species: polar...

  7. Consistency analysis of Keratograph and traditional methods to evaluate tear film function

    Directory of Open Access Journals (Sweden)

    Pei-Yang Shen

    2015-05-01

    Full Text Available AIM: To investigate repeatability and accuracy of a latest Keratograph for evaluating the tear film stability and to compare its measurements with that of traditional examination methods. METHODS: The results of noninvasive tear film break-up time(NI-BUTincluding the first tear film break-up time(BUT-fand the average tear film break-up time(BUT-avewere measured by Keratograph. The repeatability of the measurements was evaluated by coefficient of variation(CVand intraclass correlation coefficient(ICC. Wilcoxon Signed-Rank test was used to compare NI-BUT with fluorescein tear film break-up time(FBUTto confirm the correlation between NI-BUT and FBUT, Schirmer I test values. Bland-Altman analysis was used to evaluate consistency. RESULTS: The study recruited 48 subjects(48 eyes(mean age 38.7±15.2 years. The CV and ICC of BUT-f were respectively 12.6% and 0.95, those of BUT-ave were 9.8% and 0.96. The value of BUT-f was lower than that of FBUT. The difference had statistical significance(6.16±2.46s vs 7.46±1.92s, PPCONCLUSION: Keratograph can provide NI-BUT data that has a better repeatability and reliability, which has great application prospects in diagnosis and treatment of dry eye and refractive corneal surgery.

  8. Effectiveness and comfort of Oculus Keratograph on tear film function test before corneal refractive surgery

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2017-08-01

    Full Text Available AIM: To explore correlation, consistency and comfort between traditional tear film examination methods and Oculus Keratograph. METHODS: A retrospective study. Totally 101 cases(101 eyeswere diagnosed myopia and then accepted LASEK(laser epithelial keratomileusis. Non-invasive tear film break-up time(NIBUT, lower tear meniscus height(LTMHwere measured with Oculus Keratograph, fluorescein tear film break-up time(fl-BUTand Schimer Ⅰ test(SⅠtwere performed on all cases. The correlations analysis between NIBUT and fl-BUT, LTMH and SⅠt were performed by Spearman rank correlation, consistency check between NIBUT and fl-BUT by Bland-Altman analysis. Visual analogue scale(VASwas applied on evaluating the comfort of two kinds of examination methods. RESULTS: LTMH and SⅠt showed positive correlation(rs=0.346, P=0.001. NIBUT and fl-BUT showed positive correlation(rs=0.393, P=0.001, 95% consistency limits range -9.62 to 14.18 in Bland-Altman Figure. There was significant difference between VAS of NIBUT and VAS of fl-BUT(z=-2.324, P=0.020. There was significant difference between VAS of LTMH and VAS of SⅠt(z=-8.845,P=0.001.CONCLUSION: Oculus Keratograph can objectively measure NIBUT and LTMH, and was more comfortable than traditional tear film examination methods. It can effectively assess tear film function before corneal refractive surgery.

  9. Cytokine biomarkers in tear film for primary open-angle glaucoma

    Directory of Open Access Journals (Sweden)

    Gupta D

    2017-02-01

    Full Text Available Divakar Gupta,1,* Joanne C Wen,2,* Janet L Huebner,3 Sandra Stinnett,1 Virginia B Kraus,3,4 Henry C Tseng,1 Molly Walsh1 1Department of Ophthalmology, Duke University Medical Center, Durham, NC, 2Department of Ophthalmology, University of Washington, Seattle, WA, 3Duke Molecular Physiology Institute, 4Division of Rheumatology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA *These authors contributed equally to this work Purpose: To determine the utility of tear film cytokines as biomarkers for early primary open-angle glaucoma (POAG. Methods: Patients without POAG and eye drop-naïve patients with newly diagnosed POAG were recruited from an academic hospital-based glaucoma practice. Tear films of recruited patients were obtained and analyzed using a multiplex, high-sensitivity electrochemiluminescent enzyme-linked immunosorbent assay for proinflammatory cytokines (IFNγ, IL-10, IL-12p70, IL-13, IL-1β, IL-2, IL-4, IL-6, IL-8, and TNFα. Results: Mean concentrations of tear film cytokines were lower in the glaucoma group for 8 of 10 cytokines tested. IL-12p70 (3.94±2.19 pg/mL in control vs 2.31±1.156 pg/mL in POAG; P=0.035 was significantly lower in the tear film of patients with newly diagnosed POAG. Conclusion: Proinflammatory cytokines were lower in eye drop-naïve newly diagnosed glaucoma patients. Tear film cytokine profiles may be used as biomarkers of early POAG. Keywords: glaucoma, biomarkers, tear film, cytokines, glaucoma diagnosis, lower limit of detection

  10. Management of the ocular surface and tear film before, during, and after laser in situ keratomileusis.

    Science.gov (United States)

    Albietz, Julie M; Lenton, Lee M

    2004-01-01

    To identify evidence-based, best practice strategies for managing the ocular surface and tear film before, during, and after laser in situ keratomileusis (LASIK). After a comprehensive review of relevant published literature, evidence-based recommendations for best practice management strategies are presented. Symptoms of ocular irritation and signs of dysfunction of the integrated lacrimal gland/ocular surface functional gland unit are common before and after LASIK. The status of the ocular surface and tear film before LASIK can impact surgical outcomes in terms of potential complications during and after surgery, refractive outcome, optical quality, patient satisfaction, and the severity and duration of dry eye after LASIK. Before LASIK, the health of the ocular surface should be optimized and patients selected appropriately. Dry eye before surgery and female gender are risk factors for developing chronic dry eye after LASIK. Management of the ocular surface during LASIK can minimize ocular surface damage and the risk of adverse outcomes. Long-term management of the tear film and ocular surface after LASIK can reduce the severity and duration of dry eye symptoms and signs. Strategies to manage the integrated ocular surface/lacrimal gland functional unit before, during, and after LASIK can optimize outcomes. As problems with the ocular surface and tear film are relatively common, attention should focus on the use and improvement of evidence-based management strategies.

  11. Divalent cations in tears, and their influence on tear film stability in humans and rabbits.

    Science.gov (United States)

    Wei, Xiaojia Eric; Markoulli, Maria; Millar, Thomas J; Willcox, Mark D P; Zhao, Zhenjun

    2012-06-05

    Reduced tear film stability is reported to contribute to dry eye. Rabbits are known to have a more stable tear film than humans. Thus, we sought to examine the tears of rabbits and humans for metal cations, and to test how they influence tear film stability. Tears were collected from 10 healthy humans and 6 rabbits. Tear osmolality was measured by vapor pressure osmometer, and metals analyzed using inductively coupled plasma (ICP) mass spectrometry or ICP atomic emission spectroscopy. The influence of divalent cations on tears was analyzed by measuring surface tension using the Langmuir trough in vitro, using different concentrations of cations in the subphase, and grading the tear break-up in rabbits in vivo after instillation of chelating agents. Rabbit tears had a higher osmolality compared to humans. Major metals did not differ between species; however, rabbits had higher levels of Mg(2+) (1.13 vs. 0.39 mM) and Ca(2+) (0.75 vs. 0.36 mM). In rabbit tears in vitro, diminishing divalent cations resulted in a decrease in the maximum surface pressure from 37 to 30 mN/m. In vivo, an increase in the amount of tear film that was broken-up was found. In contrast, when changing divalent cation concentrations in human tears, the maximum surface pressure remained at 26 mN/m. The normal osmolality of rabbit tears is significantly higher than that in humans. While divalent cations had little influence on human tears, they appear to have an important role in maintaining tear film stability in rabbits.

  12. Tear film stability analysis system: introducing a new application for videokeratography.

    Science.gov (United States)

    Goto, Tomoko; Zheng, Xiaodong; Okamoto, Shigeki; Ohashi, Yuichi

    2004-11-01

    To review our previous studies regarding the development of a tear stability analysis system (TSAS) using videokeratography and the clinical application of TSAS for evaluation of tear film stability in patients subject to laser in situ keratomileusis (LASIK). New software, namely TSAS, was developed for the videokeratography system TMS-2N (topographic modeling system). TSAS automatically captures consecutive corneal surface images every second for 10 seconds. Corneal topographs were analyzed for tear breakup time (TMS-BUT) and tear breakup area (TMS-BUA, the ratio of breakup area to entire color-code area). First, we recruited volunteers to test the sensitivity and specificity of this new system in comparison with the routine method for tear stability analysis, tear film breakup time evaluation by slit-lamp microscope (SLE-BUT), with fluorescence staining. Second, we investigated the practicability of TSAS in dynamic evaluation of tear film stability before and after LASIK. TMS-BUT had a positive correlation with SLE-BUT, whereas TMS-BUA showed a negative correlation. Although they showed similar rates of specificity as SLE-BUT, the sensitivity rates of TMS-BUT and TMS-BUA were 97.5% and 95%, respectively, significantly higher than that of SLE-BUT (75%). The study on patients subject to LASIK showed that tear film stability significantly decreased during the early time period following LASIK and resolved at 6 months after surgery. Eyes that had abnormal TSAS evaluation tended to have higher risk of developing superficial punctuate keratitis and dry eye symptoms after LASIK, and their responses to treatment were slow. TSAS is a noninvasive and objective method with higher sensitivity for tear film stability analysis than SLE-BUT.

  13. The impact of lipid composition on the stability of the tear fluid lipid layer

    DEFF Research Database (Denmark)

    Kulovesi, P.; Telenius, J.; Koivuniemi, A.

    2012-01-01

    The tear fluid protects the corneal epithelium from drying and pathogens and it also provides nutrients to these cells. Tear fluid is composed of an aqueous layer as well as a lipid layer that resides at the air-tear interface. The function of the lipid layer is to lower the surface tension of th......-neutral lipid ratio. The results provide a plausible rationale for the development of dry eye syndrome in blepharitis patients.......The tear fluid protects the corneal epithelium from drying and pathogens and it also provides nutrients to these cells. Tear fluid is composed of an aqueous layer as well as a lipid layer that resides at the air-tear interface. The function of the lipid layer is to lower the surface tension...

  14. Lipid order, saturation and surface property relationships: a study of human meibum saturation.

    Science.gov (United States)

    Mudgil, Poonam; Borchman, Douglas; Yappert, Marta C; Duran, Diana; Cox, Gregory W; Smith, Ryan J; Bhola, Rahul; Dennis, Gary R; Whitehall, John S

    2013-11-01

    Tear film stability decreases with age however the cause(s) of the instability are speculative. Perhaps the more saturated meibum from infants may contribute to tear film stability. The meibum lipid phase transition temperature and lipid hydrocarbon chain order at physiological temperature (33 °C) decrease with increasing age. It is reasonable that stronger lipid-lipid interactions could stabilize the tear film since these interactions must be broken for tear break up to occur. In this study, meibum from a pool of adult donors was saturated catalytically. The influence of saturation on meibum hydrocarbon chain order was determined by infrared spectroscopy. Meibum is in an anhydrous state in the meibomian glands and on the surface of the eyelid. The influence of saturation on the surface properties of meibum was determined using Langmuir trough technology. Saturation of native human meibum did not change the minimum or maximum values of hydrocarbon chain order so at temperatures far above or below the phase transition of human meibum, saturation does not play a role in ordering or disordering the lipid hydrocarbon chains. Saturation did increase the phase transition temperature in human meibum by over 20 °C, a relatively high amount. Surface pressure-area studies showing the late take off and higher maximum surface pressure of saturated meibum compared to native meibum suggest that the saturated meibum film is quite molecularly ordered (stiff molecular arrangement) and elastic (molecules are able to rearrange during compression and expansion) compared with native meibum films which are more fluid agreeing with the infrared spectroscopic results of this study. In saturated meibum, the formation of compacted ordered islands of lipids above the surfactant layer would be expected to decrease the rate of evaporation compared to fluid and more loosely packed native meibum. Higher surface pressure observed with films of saturated meibum compared to native meibum

  15. Analysis of the correlation between tear film changes of allergic conjunctivitis and dry eye

    Directory of Open Access Journals (Sweden)

    Yong Li

    2014-07-01

    Full Text Available AIM: To analyze the correlation between tear film changes of allergic conjunctivitis and dry eye, then provide clinical references for better treatment. METHODS: Fifty patients with allergic conjunctivitis were taken as the observation group, the control group was selected based on 1:1 case control theory, and we chose 50 health volunteers without ocular surface diseases, xerophthalmia and systematic diseases randomly, then fluorescein(FLstaining, break-up time(BUT, Schirner I test(SⅠt, tear meniscus high(TMHand slit-lamp examinations were performed in the two groups. RESULTS: In the observation group, FL, BUT, SIt, TMH of right eyes and left eyes were statistically significant correlated(PPPCONCLUSION: Due to inflammatory mediators participation, allergic conjunctivitis could lead to the stability changes of tear film which cause in dry eye. The stability changes of allergic conjunctivitis correlate to the damage degree of epithelium.

  16. Computed tear film and osmolarity dynamics on an eye-shaped domain

    Science.gov (United States)

    Li, Longfei; Braun, Richard J.; Driscoll, Tobin A.; Henshaw, William D.; Banks, Jeffrey W.; King-Smith, P. Ewen

    2016-01-01

    The concentration of ions, or osmolarity, in the tear film is a key variable in understanding dry eye symptoms and disease. In this manuscript, we derive a mathematical model that couples osmolarity (treated as a single solute) and fluid dynamics within the tear film on a 2D eye-shaped domain. The model includes the physical effects of evaporation, surface tension, viscosity, ocular surface wettability, osmolarity, osmosis and tear fluid supply and drainage. The governing system of coupled non-linear partial differential equations is solved using the Overture computational framework, together with a hybrid time-stepping scheme, using a variable step backward differentiation formula and a Runge–Kutta–Chebyshev method that were added to the framework. The results of our numerical simulations provide new insight into the osmolarity distribution over the ocular surface during the interblink. PMID:25883248

  17. Comparative Analysis of Tear Film Levels of Inflammatory Mediators in Contact Lens Users.

    Science.gov (United States)

    Yüksel Elgin, Cansu; İskeleli, Güzin; Talaz, Serap; Akyol, Sibel

    2016-04-01

    To compare tear films levels of various inflammatory cytokines in asymptomatic contact lens (CL) users. CL users of rigid gas-permeable CLs (RGPCL) (group 1) or silicone hydrogel CLs (SiHCL) (group 2) were compared with non-CL-using healthy subjects (group 3). Tear samples were collected from subjects in each group after ensuring that there were no complications secondary to CL wear in the CL-wearing participants. Tear-film levels of interleukins (ILs)-1β, -6, and -8; granulocyte-macrophage colony-stimulating factor (GM-CSF) (using the Luminex method); and leukotriene B4 (LTB4) (using the ELISA method) were determined. Cytokine levels were compared among the three groups using analysis-of-variance (ANOVA) and Kruskall-Wallis tests. There were significant differences in concentrations of IL-1β, GM-CSF and LTB4 among the three groups (p = 0.002, p = 0.021 and p = 0.009, respectively), as shown by the Kruskall-Wallis test comparing all three groups for the three cytokines. There were no significant differences for IL-6 and IL-8 (p = 0.079 and 0.094, respectively) when all three groups were compared. There were substantial statistically significant differences between RGPCL users, SiHCL users and control subjects in levels of tear film cytokines. Although CL users were asymptomatic, changes in tear-film levels of several important inflammatory mediators revealed that a chronic inflammatory process occurs during CL wear.

  18. The effects of radiant cooling versus convective cooling on human eye tear film stability and blinking rate

    DEFF Research Database (Denmark)

    Nygaard, Linette; Uth, Simon C.; Bolashikov, Zhecho Dimitrov

    2014-01-01

    The effect of indoor temperature, radiant and convective cooling on tear film stability and eye blink frequency was examined. 24 human subjects were exposed to the non-uniform environment generated by localised chilled beam and a chilled ceiling combined with overhead mixing ventilation. The subj......The effect of indoor temperature, radiant and convective cooling on tear film stability and eye blink frequency was examined. 24 human subjects were exposed to the non-uniform environment generated by localised chilled beam and a chilled ceiling combined with overhead mixing ventilation....... The subjects participated in four two-hour experiments. The room air temperature was kept at 26 °C or 28 °C. Tear film samples were collected after 30 min of acclimatisation and at the end of the exposures. Eye blinking frequency was analysed for the first and last 15 min of each exposure. The tear film...... stability decreased as the temperature increased. The highest number of subjects with unchanged or improved tear film quality was observed with the localised chilled beam at 26 °C. A trend was found between subjects who reported eye irritation and had a bad tear film quality....

  19. Tear Film and Ocular Surface Changes in Patients Receiving Systemic Isotretinoin

    Directory of Open Access Journals (Sweden)

    Ebru Nevin Çetin

    2013-10-01

    Full Text Available Purpose: Our aim in this study was to assess the ocular surface and tear film changes in acne vulgaris patients receiving systemic isotretinoin. Material and Method: Twenty-two eyes of 22 patients who received oral isotretinoin (roaccutane®, 0.7 mg/kg/day for nodular acne vulgaris were enrolled in this prospective study. Tear film break-up time (BUT, Schirmer 1 test scores with anesthesia, ocular surface disease index (OSDI scores and conjunctival impression cytology scores were recorded before treatment and at 3- and 6-month visits following the beginning of treatment. Results: BUT values decreased and OSDI scores significantly increased at 3 months after treatment (p=0.007 and p=0.018, paired samples test. Schirmer scores did not significantly change by isotretinoin treatment. Of 9 eyes with impression cytology specimens, 4 revealed normal conjunctival findings before treatment. At the 3rd month, there was an increase in the scores characterized by decrease of Goblet cells, and at 6 months of treatment, normal conjunctival findings did not exist in any of the patients (p=0.004, Friedman test. Discussion: Systemic isotretinoin treatment can cause alterations in the tear film and cause dry eye symptoms. (Turk J Ophthalmol 2013; 43: 309-12

  20. Comparative study on fractal analysis of interferometry images with application to tear film surface quality assessment.

    Science.gov (United States)

    Szyperski, Piotr D

    2018-06-01

    The purpose of this research was to evaluate the applicability of the fractal dimension (FD) estimators to assess lateral shearing interferometric (LSI) measurements of tear film surface quality. Retrospective recordings of tear film measured with LSI were used: 69 from healthy subjects and 41 from patients diagnosed with dry eye syndrome. Five surface quality descriptors were considered, four based on FD and a previously reported descriptor operating in a spatial frequency domain (M 2 ), presenting temporal kinetics of post-blink tear film. A set of 12 regression parameters has been extracted and analyzed for classification purposes. The classifiers are assessed in terms of receiver operating characteristics and areas under their curves (AUC). Also, the computational loads are estimated. The maximum AUC of 82.4% was achieved for M 2 , closely followed by the binary box-counting (BBC) FD estimator with AUC=78.6%. For all descriptors, statistically significant differences between the subject groups were found (pfilm kinetics. They provide a viable alternative to previously used spectral counter parameters, and at the same time allow higher computational efficiency.

  1. Influence of preoperative artificial tears on tear film after phacoemulsification on dry eye of diabetes patients

    Directory of Open Access Journals (Sweden)

    Rui Su

    2015-05-01

    Full Text Available AIM: To discuss the artificial tears on the tear film of diabetic patients with dry eye preoperatively, and the influence on the tear film's fuctional after phacoemulsification.METHODS: Fifty-four diabetic patients with dry eye(60 eyeswere followed up before phacoemulsification. Preoperatively, group A(30 eyes in 28 caseswas treated with Hydroxyl Indican eye drops and group B(30 eyes in 26 caseswas not treated. Postoperatively, both group A and B were treated with Tobramycin Dexamethasone eye drops, Oprah Winfrey Ibuprofen eye drops and Hydroxyl Indican eye drops. Dry eye symptoms, break up time(BUT, Schirmer Ⅰ test(S Ⅰ t, fluorescein stain test(FIwere measured at 3d preoperatively, and 1, 7, 30, 90d postoperatively.RESULTS: At 3d preoperatively, there was no statistical differences between the two groups for dry eye symptoms, BUT, SⅠt, FI(P>0.05. At 1 and 7d postoperatively, there were significant statistical differents between the two groups for dry eye symptoms(PPP>0.05.CONCLUSION: Using artificial tears before phacoemulsification can improve symptoms of the diabetic patients with dry eye and accelerate the recovery of the tear film.

  2. Effects of diquafosol sodium eye drops on tear film stability in short BUT type of dry eye.

    Science.gov (United States)

    Shimazaki-Den, Seika; Iseda, Hiroyuki; Dogru, Murat; Shimazaki, Jun

    2013-08-01

    To investigate the effects of diquafosol sodium (DQS) eye drops, a purinergic P2Y2 receptor agonist, on tear film stability in patients with unstable tear film (UTF). Two prospective studies were conducted. One was an exploratory nonrandomized trial on 39 eyes with dry eye symptoms and short tear film break-up time (BUT), but without epithelial damage. Changes in symptoms, BUT, Schirmer value, and ocular surface fluorescein staining (FS) scores were studied for 3 months. The other was a randomized clinical trial of DQS and artificial tears (AT) in 17 eyes with short BUT. Eyes with decreased Schirmer values (≤ 5 mm) were excluded. Changes in symptoms, BUT, FS scores, and tear film stability using continuous corneal topographic analysis were studied for 4 weeks. In the exploratory study, while Schirmer values were not significantly increased, significant improvements in symptoms and BUT were noted at both 1 and 3 months. In the randomized clinical trial, significant improvements in symptoms were noted in the DQS group, but not in the AT group, at 2 weeks. BUT was significantly prolonged in the DQS group at 4 weeks but not in the AT group. No significant changes were noted in FS scores or tear film stability. DQS improved subjective symptoms and prolonged BUT in eyes with UTF not associated with low tear secretion and ocular surface epithelial damage. Because many patients who have UTF are refractory to conventional treatments, DQS may offer benefits in the treatment of dry eyes.

  3. Bacterial S-layer protein coupling to lipids

    DEFF Research Database (Denmark)

    Weygand, M.; Wetzer, B.; Pum, D.

    1999-01-01

    structure before and after protein recrystallization shows minimal reorganization of the lipid chains. By contrast, the lipid headgroups show major rearrangements. For the B. sphaericus CCM2177 protein underneath DPPE monolayers, x-ray reflectivity data suggest that amino acid side chains intercalate......The coupling of bacterial surface (S)-layer proteins to lipid membranes is studied in molecular detail for proteins from Bacillus sphaericus CCM2177 and B. coagulans E38-66 recrystallized at dipalmitoylphosphatidylethanolamine (DPPE) monolayers on aqueous buffer. A comparison of the monolayer...... the lipid headgroups at least to the phosphate moieties, and probably further beyond. The number of electrons in the headgroup region increases by more than four per lipid. Analysis of the changes of the deduced electron density profiles in terms of a molecular interpretation shows...

  4. Regional Differences in Tear Film Stability and Meibomian Glands in Patients With Aqueous-Deficient Dry Eye.

    Science.gov (United States)

    Koh, Shizuka; Ikeda, Chikako; Fujimoto, Hisataka; Oie, Yoshinori; Soma, Takeshi; Maeda, Naoyuki; Nishida, Kohji

    2016-07-01

    To noninvasively investigate regional differences in tear film stability and meibomian glands in patients with aqueous-deficient dry eye. Forty-nine dry eyes and 31 normal eyes were analyzed. A corneal topographer with a tear film scanning function was used for noninvasive tear film break-up time (NI-TFBUT) measurements and meibomian gland observations. The NI-TFBUT values and location of the first tear film break-up point were recorded in four quadrants. Meibomian gland loss was graded for each eyelid using meiboscores. Lid margin abnormality was scored from zero to four according to the number of existing abnormalities. The NI-TFBUT values and meiboscores were compared between two groups, and regional differences in NI-TFBUT values and meiboscores were analyzed. Also, the correlation between the NI-TFBUT and ocular surface examination results were investigated. The NI-TFBUT values and meiboscores were significantly lower and higher, respectively, for the dry eye group than for the normal group. In the dry eye group, the occurrence rate for first tear film break-up was the highest in the inferior nasal quadrant, and the mean meiboscore was significantly higher for the upper eyelids than for the lower eyelids. The NI-TFBUT and lid margin abnormality scores showed a weak negative correlation, and the NI-TFBUT values and meiboscores showed no correlation. Compared to normal eyes, aqueous-deficient dry eyes show significant regional differences in tear film stability and meibomian glands. Considering these regional differences, the overall observation of the ocular surface, including both upper and lower eyelids, will aid clinicians in understanding this condition better.

  5. Diquafosol Ophthalmic Solution Increases Pre- and Postlens Tear Film During Contact Lens Wear in Rabbit Eyes.

    Science.gov (United States)

    Nagahara, Yukiko; Koh, Shizuka; Oshita, Yoshihiro; Nagano, Takashi; Mano, Hidetoshi; Nishida, Kohji; Watanabe, Hitoshi

    2017-11-01

    To investigate the behavior of prelens tear film (PLTF) and postlens tear film (PoLTF) after the instillation of diquafosol using an experimental rabbit model of eyes with contact lens. Cross-sectional, anterior segment optical coherence tomographic images of the inferior midperipheral cornea were obtained at baseline and at 5, 15, 30, 60, 90, and 120 min after the instillation of 3% diquafosol ophthalmic solution in 10 Japanese white rabbits wearing contact lenses. From the obtained images, the areas of the PLTF and PoLTF were calculated. Both artificial tear solution and 0.1% sodium hyaluronate ophthalmic solution were used for comparison. Significant fluid accumulation in both the PLTF and PoLTF was observed after diquafosol instillation, whereas no fluid accumulation was visible after the instillation of artificial tear or sodium hyaluronate. The increase in PLTF area after diquafosol instillation was significantly higher (Pophthalmic solution increases PLTF and PoLTF in rabbit eyes with contact lenses. Diquafosol has potential as a treatment option for contact lens-related dry eye.

  6. Changes of tear film after LASIK with corneal flap created by femtosecond laser and microkeratome

    Directory of Open Access Journals (Sweden)

    Yuan Zhang

    2014-09-01

    Full Text Available AIM: To observe the changes of tear film on the patients after laser in situ keratomileusis(LASIKwith corneal flap created by femtosecond laser and microkeratome.METHODS: Totally 150 patients(300 eyeswith myopia received operation of LASIK. Patients were divided into two groups according to the methods of making corneal flap. The patients of group one were assigned to receiving LASIK with corneal flap creation by Intralase femtosecond laser(190 eyes of 95 patients, group two were assigned to receiving LASIK with corneal flap creation by microkeratome(110 eyes of 55 patients. Dry eye symptom score, tear break-up time(BUT, Schirmer Ⅰ test(S I t, corneal fluorescein staining(FLwere recorded preoperatively and postoperatively at 1wk; 1, 3 and 6mo. RESULTS: Dry eye symptom score: there existed obvious differences at 1wk; 1, 3mo between two groups(PP>0.05. BUT: there existed obvious differences at 1wk, 1, 3mo between two groups(PP>0.05. SchirmerⅠ test: there existed obvious differences in the 1wk, 1, 3mo between two groups(PP>0.05. FL: there existed obvious differences in the 1wk, 1, 3mo between two groups(PP>0.05.CONCLUSION: The early stability of tear film decrease after operation in both of the two groups. The dry eye symptoms are lighter and recover faster.

  7. The effect of smoking on the ocular surface and the precorneal tear film

    Directory of Open Access Journals (Sweden)

    Jyothi Thomas

    2012-04-01

    Full Text Available BackgroundSmoking, both active and passive, creates a plethora ofhealth‐related problems, which primarily affect thecardiovascular and respiratory systems. There is very littleevidence on the effects of tobacco smoke on the eye,especially regarding anterior ocular surface relatedpathology. This study was undertaken to determine theeffects of smoking on the ocular surface and the tear film insmokers.MethodsA total of 51 (102 eyes smokers and 50 (100 eyes age‐ andgender‐matched healthy non‐smokers were included in thisstudy. The ocular surface was evaluated by measuring tearfilm break‐up time, surface staining with fluorescein, andcorneal and conjunctival sensitivities, and by completing theSchirmer’s II test. Data was analysed using StatisticalPackage for Social Sciences (SPSS version 11.5. A p valueless than 0.05 was considered statistically significant.ResultsThe smoker group had significantly lower tear film break‐uptime, and corneal and conjunctival sensitivity than the nonsmokergroup. Punctate staining was significantly higher inthe smoker group than the non‐smoker group. There wasno statistically significant difference in Schirmer’s II testresults between the smoker and non‐smoker group.ConclusionSmoking caused adverse effects on the precorneal tear filmand there was strong association between smoking and tearfilm instability. Although a causative relationship could notbe determined, there is a need for further longitudinalstudies.

  8. Corneal cell adhesion to contact lens hydrogel materials enhanced via tear film protein deposition.

    Directory of Open Access Journals (Sweden)

    Claire M Elkins

    Full Text Available Tear film protein deposition on contact lens hydrogels has been well characterized from the perspective of bacterial adhesion and viability. However, the effect of protein deposition on lens interactions with the corneal epithelium remains largely unexplored. The current study employs a live cell rheometer to quantify human corneal epithelial cell adhesion to soft contact lenses fouled with the tear film protein lysozyme. PureVision balafilcon A and AirOptix lotrafilcon B lenses were soaked for five days in either phosphate buffered saline (PBS, borate buffered saline (BBS, or Sensitive Eyes Plus Saline Solution (Sensitive Eyes, either pure or in the presence of lysozyme. Treated contact lenses were then contacted to a live monolayer of corneal epithelial cells for two hours, after which the contact lens was sheared laterally. The apparent cell monolayer relaxation modulus was then used to quantify the extent of cell adhesion to the contact lens surface. For both lens types, lysozyme increased corneal cell adhesion to the contact lens, with the apparent cell monolayer relaxation modulus increasing up to an order of magnitude in the presence of protein. The magnitude of this increase depended on the identity of the soaking solution: lenses soaked in borate-buffered solutions (BBS, Sensitive Eyes exhibited a much greater increase in cell attachment upon protein addition than those soaked in PBS. Significantly, all measurements were conducted while subjecting the cells to moderate surface pressures and shear rates, similar to those experienced by corneal cells in vivo.

  9. Solute Dynamics and Imaging in the Tear Film on an Eye-shaped Domain

    Science.gov (United States)

    Braun, R. J.; Li, Longfei; Henshaw, William; Driscoll, Tobin; King-Smith, P. E.

    2015-11-01

    The concentration of ions in the tear film (osmolarity) is a key variable in understanding dry eye symptoms and disease, yet its global distribution is not available; direct measurements are restricted to a region near the temporal canthus. It has been suggested that imaging methods that use solutes such as fluorescein can be used as a proxy for estimating the osmolarity. The concentration of fluorescein is not measured directly either but the intensity as a function of concentration and thickness of the film is well established. We derived a mathematical model that couples multiple solutes and fluid dynamics within the tear film on a 2D eye-shaped domain. The model includes the physical effects of evaporation, surface tension, viscosity, ocular surface wettability, osmolarity, osmosis, fluorescence and tear fluid supply and drainage. We solved the governing system of coupled nonlinear PDEs using the Overture computational framework developed at LLNL, together with a hybrid time stepping scheme (using variable step BDF and RKC). Results of our numerical simulations provide new insight about the osmolarity distribution and its connection with images obtained in vivo over the whole ocular surface and in local regions of tear thinning due to evaporation and other effects. This work was supported in part by NSF grants 1022706 and 1412085, and NIH grant 1R01EY021794.

  10. Antimicrobial role of human meibomian lipids at the ocular surface.

    Science.gov (United States)

    Mudgil, Poonam

    2014-10-14

    Human meibomian lipids form the outermost lipid layer of the tear film and serve many important functions to maintain its integrity. Although not investigated earlier, these lipids may have antimicrobial properties that help in strengthening the innate host defense of tears at the ocular surface. The aim of this study was to investigate the antimicrobial role of human meibomian lipids. Ocular pathogenic bacteria, Staphylococcus aureus 31, Pseudomonas aeruginosa 19, Pseudomonas aeruginosa 20, and Serratia marcescens 35, were grown in the presence and absence of human meibomian lipids in an artificial tear solution at the physiological temperature. Viable counts were obtained to note the number of bacteria surviving the treatment with meibomian lipids. Bacterial cells were imaged using scanning electron microscopy to observe the damages caused by meibomian lipids. Viable count results showed that in the presence of meibomian lipids, growth of all bacteria was considerably lower. Scanning electron microscopy showed that meibomian lipids caused extensive cellular damage to bacteria as manifested in smaller size, loss of aggregation, abnormal phenotype, cellular distortion, damaged cell wall, and cell lysis. This is the first-ever report of the antimicrobial role of human meibomian lipids. These lipids possess antimicrobial properties against both Gram-positive and Gram-negative bacteria and are involved in the innate host defense of tears in protecting the ocular surface against microbial pathogens. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  11. Effect of three different liposomal eye sprays on ocular comfort and tear film.

    Science.gov (United States)

    Pult, Heiko; Gill, Felicity; Riede-Pult, Britta H

    2012-10-01

    To evaluate the effect of three different liposomal eye sprays on ocular comfort and tear film stability. OptrexActiMist (AM, Optima-Pharma, Germany) was applied onto one, randomly selected eye of 80 subjects (female=49; mean age=49 years±18.6 SD) in a multi-centred, double-masked study. DryEyesMist (DEM, Boots) or TearMist (TM, Tesco) was applied onto the contralateral eye in randomized order. Over-all symptoms were investigated using the Ocular Surface Disease Index (OSDI). Ocular comfort (visual-analogue scale 0-100 [100=perfect]) and non-invasive tear film stability (NIBUT) of each eye was evaluated before application (randomized order) and were again measured 10 min after application. Effects of products on ocular comfort and NIBUT were calculated as "factor" (=after-treatment/before-treatment). Differences between measurements were analysed by ANOVA repeated measurements and differences between groups by the dependent t-test (or the non-parametric equivalent). OSDI-scores (mean=8.1±9.0 SD), comfort (65±24) and NIBUT (12 s±12.3) were statistically similar between centres (p>0.400). Comfort and NIBUT were not different (p>0.14) between product groups before application. Comfort and NIBUT improved significantly after application of AM (p<0.001) but worsened with the comparing products (p<0.058). Comfort improved by a mean factor of 1.5 (±0.82 SD) after application of AM but decreased after application of the comparing products (DEM: 0.9±0.33; TM: 0.9±0.34). Both factors were significantly better in AM (p<0.027). The original liposomal eye-spray 'OptrexActiMist' significantly improved ocular comfort and tear film stability while 'TearMist' or 'DryEyesMist' worsened both criteria. The latter two products may not be clinically effective in the treatment of dry eye. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  12. Role of Neutral Lipids in Tear Fluid Lipid Layer: Coarse-Grained Simulation Study

    DEFF Research Database (Denmark)

    Telenius, J.; Koivuniemi, A.; Kulovesi, P.

    2012-01-01

    Tear fluid lipid layer (TFLL) residing at the air-water interface of tears has been recognized to play an important role in the development of dry eye syndrome. Yet, the composition, structure, and mechanical properties of TFLL are only partly known. Here, we report results of coarse...

  13. [The correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK].

    Science.gov (United States)

    Zhang, Luyan; Sun, Xiyu; Yu, Ye; Xiong, Yan; Cui, Yuxin; Wang, Qinmei; Hu, Liang

    2016-01-01

    To investigate the correlations between corneal sensation, tear meniscus volume, and tear film osmolarity after femtosecond laser-assisted LASIK (FS-LASIK) surgery. In this prospective clinical study, 31 patients undergoing FS-LASIK for myopia were recruited. The upper and lower tear meniscus volumes (UTMV and LTMV) were measured by customized anterior segment optical coherence tomography, tear film osmolarity was measured by a TearLab Osmolarity test device, central corneal sensation was measured by a Cochet-Bonner esthesiometer preoperatively, at 1 week, 1 and 3 months postoperatively. Repeated measures analysis of variance was used to evaluate whether the tear film osmolarity, tear meniscus volume, and corneal sensation were changed after surgery. The correlations between these variables were analyzed by the Pearson correlation analysis. The tear film osmolarity was (310.03 ± 16.48) mOsms/L preoperatively, (323.51 ± 15.92) mOsms/L at 1 week, (319.93 ± 14.27) mOsms/L at 1 month, and (314.97±12.91) mOsms/L at 3 months. The UTMV was (0.42±0.15), (0.25± 0.09), (0.30±0.11), and (0.35±0.09) μL, respectively; the LTMV was (0.60±0.21),(0.37±0.08), (0.44± 0.14), and (0.52±0.17) μL, respectively. The tear film osmolarity was significantly higher at 1 week and 1 month postoperatively compared with the baseline (P=0.001, 0.004), and reduced to the preoperative level at 3 months (P=0.573). The UTMV, LTMV, and corneal sensation values presented significant decreases at all postoperative time points (all Psensation at 1 week after surgery (r=0.356,P=0.005). There were significant correlations between the preoperative LTMV and corneal sensation at 1 week, 1 and 3 months (respectively, r=0.422, 0.366, 0.352;P=0.001, 0.004, 0.006). No significant correlations were found between the tear film osmolarity, tear meniscus volume, and corneal sensation after surgery (all P>0.05). The tear film osmolarity, tear meniscus volume, and corneal sensation became aggravated due

  14. Global existence of solutions to a tear film model with locally elevated evaporation rates

    Science.gov (United States)

    Gao, Yuan; Ji, Hangjie; Liu, Jian-Guo; Witelski, Thomas P.

    2017-07-01

    Motivated by a model proposed by Peng et al. (2014) for break-up of tear films on human eyes, we study the dynamics of a generalized thin film model. The governing equations form a fourth-order coupled system of nonlinear parabolic PDEs for the film thickness and salt concentration subject to non-conservative effects representing evaporation. We analytically prove the global existence of solutions to this model with mobility exponents in several different ranges and present numerical simulations that are in agreement with the analytic results. We also numerically capture other interesting dynamics of the model, including finite-time rupture-shock phenomenon due to the instabilities caused by locally elevated evaporation rates, convergence to equilibrium and infinite-time thinning.

  15. Organization of Lipids in the Tear Film: A Molecular- Level View

    Czech Academy of Sciences Publication Activity Database

    Wizert, A.; Iskander, D. R.; Cwiklik, Lukasz

    2014-01-01

    Roč. 9, č. 3 (2014), e92461 E-ISSN 1932-6203 Institutional support: RVO:61388955 Keywords : DRY EYE DISEASE * CONTACT-LENS WEARERS * COARSE-GRAINED MODEL Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.234, year: 2014

  16. Organization of Lipids in the Tear Film: A Molecular-Level View

    Czech Academy of Sciences Publication Activity Database

    Wizert, A.; Iskander, D. R.; Cwiklik, Lukasz

    2014-01-01

    Roč. 9, č. 3 (2014), č. článku e92461. E-ISSN 1932-6203 Institutional support: RVO:61388963 Keywords : dry eye disease * contact lens wearers * coarse grained model Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.234, year: 2014 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092461

  17. Lipid and protein maps defining arterial layers in atherosclerotic aorta

    Directory of Open Access Journals (Sweden)

    Marta Martin-Lorenzo

    2015-09-01

    Full Text Available Subclinical atherosclerosis cannot be predicted and novel therapeutic targets are needed. The molecular anatomy of healthy and atherosclerotic tissue is pursued to identify ongoing molecular changes in atherosclerosis development. Mass Spectrometry Imaging (MSI accounts with the unique advantage of analyzing proteins and metabolites (lipids while preserving their original localization; thus two dimensional maps can be obtained. Main molecular alterations were investigated in a rabbit model in response to early development of atherosclerosis. Aortic arterial layers (intima and media and calcified regions were investigated in detail by MALDI-MSI and proteins and lipids specifically defining those areas of interest were identified. These data further complement main findings previously published in J Proteomics (M. Martin-Lorenzo et al., J. Proteomics. (In press; M. Martin-Lorenzo et al., J. Proteomics 108 (2014 465–468. [1,2].

  18. Tear film dynamics with evaporation, wetting, and time-dependent flux boundary condition on an eye-shaped domain

    Science.gov (United States)

    Li, Longfei; Braun, R. J.; Maki, K. L.; Henshaw, W. D.; King-Smith, P. E.

    2014-01-01

    We study tear film dynamics with evaporation on a wettable eye-shaped ocular surface using a lubrication model. The mathematical model has a time-dependent flux boundary condition that models the cycles of tear fluid supply and drainage; it mimics blinks on a stationary eye-shaped domain. We generate computational grids and solve the nonlinear governing equations using the OVERTURE computational framework. In vivo experimental results using fluorescent imaging are used to visualize the influx and redistribution of tears for an open eye. Results from the numerical simulations are compared with the experiment. The model captures the flow around the meniscus and other dynamic features of human tear film observed in vivo. PMID:24926191

  19. [Clinical characteristics of short tear film breakup time (BUT) -type dry eye].

    Science.gov (United States)

    Yamamoto, Yuji; Yokoi, Norihiko; Higashihara, Hisayo; Inagaki, Kayoko; Sonomura, Yukiko; Komuro, Aoi; Kinoshita, Shigeru

    2012-12-01

    To evaluate the clinical characteristics and management of short tear film breakup time (BUT) -type dry eye. Clinical background and post-treatment changes of symptoms in 77 patients with short BUT -type dry eye were investigated. Treatment consisted of artificial-tear eye-drop instillation and, if necessary, the addition of a low-density-level steroid, hyaluronic acid, a low-density-level cyclopentolate prepared by ourselves and punctal plugs inserted into the upper and lower lacrimal puncta. There were three times more women than men among the patients, and the peak age of occurrence was in the twenties in the men and in the sixties in the women. Our findings show that visual display terminal (VDT) work, contact lens (CL) wear, and changes in the sex hormones may initiate subjective symptoms. Some patients had simultaneous conjunctivochalasis, allergic conjunctivitis, and meibomian gland dysfunction. Nineteen patients (24.7%) were effectively treated with eye-drop instillation alone. Thirty-seven patients (48.1%) required punctal-plug insertion, which was completely effective in only 8 of them (21.6%). Mainly young men and menopausal women contract short BUT -type dry eye. Changes in sex hormones, VDT work and CL wear may be causal, and the disease cannot be controlled by eyedrop and punctal-plug treatment alone.

  20. Effect of contact lens wear and a near task on tear film break-up.

    Science.gov (United States)

    Jansen, Meredith E; Begley, Carolyn G; Himebaugh, Nikole H; Port, Nicholas L

    2010-05-01

    To study the effect of extrinsic controls on blinking by examining blink parameters and tear stability among adapted soft contact lens (CL) wearers performing tasks that require varying amounts of visual concentration. The Demographic Questionnaire, Contact Lens Dry Eye Questionnaire, and Current Symptoms Questionnaire were completed by 15 adapted soft CL wearers (nine females). Three 55 s simultaneous measurements of tear film stability via retroillumination and blinking were obtained with a slit-lamp biomicroscope and 200 Hz video camera while subjects listened to music and played a video game with and without their habitual CLs. Interblink interval (IBI) and blink amplitude (BA) were calculated. The area of break-up (AB) was calculated for the retroillumination image before each blink. The Current Symptoms Questionnaire was completed four times throughout testing. With the game compared to music, IBI was significantly longer and BA significantly decreased without CLs (p or = 0.5579, p or = 0.6262, p or = 0.5064, p film instability increased. Blinking frequency also increased, but it remained high when subjects played the game, and symptoms of ocular irritation increased. This suggests that wearing soft CLs, even when fully adapted, provides enough extrinsic ocular surface stimulation to override internal controls and affect blink parameters.

  1. Layered lipid microcapsules for mesalazine delayed-release in children.

    Science.gov (United States)

    Balducci, Anna Giulia; Colombo, Gaia; Corace, Giuseppe; Cavallari, Cristina; Rodriguez, Lorenzo; Buttini, Francesca; Colombo, Paolo; Rossi, Alessandra

    2011-12-15

    The goal was to make available a delayed-release dosage form of mesalazine to be dispersed in water to facilitate swallowing in adults and children. Mesalazine microparticles containing carnauba wax were prepared by spray-congealing technique. A second step of spray-congealing of carnauba microparticles dispersed in liquefied stearic acid gave rise to mesalazine lipid microcapsules in which several carnauba microparticles remained embedded as cores in a reservoir structure. In order to favor their water dispersion, the lipid microcapsules were dry coated by tumbling them with different ratios of mannitol/lecithin microparticles prepared by spray-drying. Release rate measurements showed a delayed-release behavior, in particular a pH-dependence with less than 10% of drug released in acidic medium and complete release in phosphate buffer pH 7.4 in 4-5h. The layering with hydrophilic excipient microparticles allowed manufacturing of a pH-dependent dosage form suitable for extemporaneous oral use in adults and children. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Ocular Surface and Tear Film Changes in Older Women Working with Computers

    Directory of Open Access Journals (Sweden)

    Alfredo Ribelles

    2015-01-01

    Full Text Available The aim of this work is to investigate changes in the ocular surface (OS and tear film (TF by means of questionnaire-based subjective symptoms, TF break-up time, Schirmer test, and TF analysis in women working with computers and to analyze the effects of the oral supplementation with antioxidants/omega 3 fatty acids (A/ω3 in the OS outcomes. Women aged 40–65 years (n=148 were recruited at the Administrative Offices of Valencia (Spain and distributed into two age groups, 40–52 years (AGE1; n=87 and 53–65 years (AGE2; n=61, and then subdivided according to being (or not computer users (CUG; NCUG during the workday. Homogeneous subgroups were randomly assigned (or not to the daily intake of three pills of A/ω3 for three months. At baseline and at the end of follow-up, personalized interviews and ocular examination were done. Reflex tear samples were collected from the inferior meniscus and processed for a multiplexed particle-based flow cytometry assay to measure proinflammatory molecules. Statistics were performed using the SPSS 15.0 program. The OS pathology was clinically evident in the AGE1-CUG (33% versus the AGE2-CUG (64% of women. Significantly higher interleukins-1β and -6 tear levels were found in the AGE1 versus the AGE2 women employees (P=0.006 and P=0.001, resp., as well as in the CUG versus the NCUG (P=0.001 and P=0.000, resp.. Supplementation with A/ω3 positively influenced the OS pathology as manifested by the amelioration of the clinical signs/symptoms related to computer uses. Strategies involving a safe environment and oral micronutrient supplements may be managed within eye-care standards in older women.

  3. Effects of wearing a daily disposable lens on tear film: a randomised controlled trial.

    Science.gov (United States)

    Chong, Pamela Qin Yi; Yeo, Sharon; Too, Cheah Loon; Boo, Cynthia; Tong, Louis

    2016-05-01

    Contact lens-induced dry eye is commonly encountered, although its extent is not well documented with daily disposable lenses. A novel type of contact lens system incorporating moisturising agent (alginic acid) has been developed. The aim of this study was to evaluate the effect of wearing daily 2-hydroxyethyl methacrylate disposable contact lenses for seven days on tear stability, conjunctival and limbal redness and dry eye symptoms. Then, we aimed to determine whether lens solutions containing alginic acid had any influence on tear parameters. This was a seven-day parallel group double-masked clinical trial of previous contact lens wearers, where participants were randomly assigned to wearing SEED 1dayPure moisture contact lenses with (n = 15) or without alginic acid (n = 15). Tear lipid layer thickness (LLT), non-invasive tear break-up time (NIBUT), conjunctival redness, corneal fluorescein staining, tear break-up time and Schirmer I readings were measured. Symptom severity and frequency were evaluated and combined using a global score from visual analogue scales. The mean age and standard deviation of the participants was 25 ± 3.8 years. There were 24 females and six males. After reintroduction of contact lens wear for one week, there was significant improvement in the global symptom score; however, this may not be clinically significant. There were small and clinically insignificant changes in limbal and conjunctival hyperaemia but no significant changes in lipid layer thickness, Schirmer I and NIBUT in overall participants. The use of alginic acid in lens solutions did not affect these parameters compared to control lenses (p > 0.05). After seven days of wearing a modern daily disposable lens, there was no significant deterioration of tear function in a group of young contact lens wearers. In this short-term study, there was no evidence of significant benefit of lens solutions containing alginic acid used with HEMA lenses. © 2016 The Authors Clinical and

  4. Effect of Omega-3 Fatty Acids Dietary Supplementation on Ocular Surface and Tear Film in Diabetic Patients with Dry Eye.

    Science.gov (United States)

    Georgakopoulos, Constantine D; Makri, Olga E; Pagoulatos, Dionisios; Vasilakis, Panagiotis; Peristeropoulou, Politimi; Kouli, Vasiliki; Eliopoulou, Maria I; Psachoulia, Caterina

    2017-01-01

    The objective of this study was to investigate the effect of dietary supplementation with omega-3 fatty acids on ocular surface and tear film in patients with type 2 diabetes suffering from dry eye. Thirty-six patients suffering from type 2 diabetes and moderate to severe dry eye syndrome were included in the study. Patients were assigned to receive omega-3 long-chain polyunsaturated fatty acids for 3 months. Tear film break-up time test, Schirmer-I test, and conjunctival impression cytology analysis were performed on all patients at baseline and after 1 and 3 months. The subjective symptoms of dry eye were evaluated with the Ocular Surface Disease Index (OSDI) questionnaire at the same time points. Patients' average age was 65.57 ± 4.27 years and the mean duration of diabetes was 14.85 ± 5.4 years. There was a statistically significant increase in Schirmer-I test results and tear break-up time score after 3 months of supplementary intake of omega-3 fatty acids compared to baseline (p dry eye syndrome in patients with type 2 diabetes.

  5. Dry eye evaluation and correlation analysis between tear film stability and corneal surface regularity after small incision lenticule extraction.

    Science.gov (United States)

    Zhang, Hui; Wang, Yan

    2017-09-22

    To investigate the dry eye after small incision lenticule extraction (SMILE) and explore the correlations between changes in the tear film stability, the tear secretion and the corneal surface regularity. Sixty-two eyes of 22 men and 13 women who underwent SMILE were included in this study. Corneal topography was measured to assess the index of surface variance (ISV) and the index of vertical asymmetry (IVA). Dry eye tests including subjective symptom questionnaire, tear breakup time (TBUT), corneal fluorescein staining and Schirmer's test (ST) were evaluated before and at 1 and 6 months postoperatively. TBUT was found to be significantly decreased from 9.8 ± 3.4 s preoperatively to 7.4 ± 3.8 s at 1 month and 6.5 ± 3.6 s at 6 months (both P short-TBUT type of dry eye. Corneal surface regularity indices might be helpful in the assessment of tear film stability following SMILE procedure.

  6. Evaporation and Hydrocarbon Chain Conformation of Surface Lipid Films

    Science.gov (United States)

    Sledge, Samiyyah M.; Khimji, Hussain; Borchman, Douglas; Oliver, Alexandria; Michael, Heidi; Dennis, Emily K.; Gerlach, Dylan; Bhola, Rahul; Stephen, Elsa

    2016-01-01

    Purpose The inhibition of the rate of evaporation (Revap) by surface lipids is relevant to reservoirs and dry eye. Our aim was to test the idea that lipid surface films inhibit Revap. Methods Revap were determined gravimetrically. Hydrocarbon chain conformation and structure were measured using a Raman microscope. Six 1-hydroxyl hydrocarbons (11–24 carbons in length) and human meibum were studied. Reflex tears were obtained from a 62-year-old male. Results The Raman scattering intensity of the lipid film deviated by about 7 % for hydroxyl lipids and varied by 21 % for meibum films across the entire film at a resolution of 5 µm2. All of the surface lipids were ordered. Revap of the shorter chain hydroxyl lipids were slightly (7%) but significantly lower compared with the longer chain hydroxyl lipids. Revap of both groups was essentially similar to that of buffer. A hydroxyl lipid film did not influence Revap over an estimated average thickness range of 0.69 to >6.9 µm. Revap of human tears and buffer with and without human meibum (34.4 µm thick) was not significantly different. Revap of human tears was not significantly different from buffer. Conclusions Human meibum and hydroxyl lipids, regardless of their fluidity, chain length, or thickness did not inhibit Revap of buffer or tears even though they completely covered the surface. It is unlikely that hydroxyl lipids can be used to inhibit Revap of reservoirs. Our data do not support the widely accepted (yet unconfirmed) idea that the tear film lipid layer inhibits Revap of tears. PMID:27395776

  7. Effect of rb-bFGF eye drops and hydroxyl indican eye drops on tear film stability and dry eye symptoms after age-related cataract surgery

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2017-10-01

    Full Text Available AIM: To compare and analyze the effect of recombinant bovine basic fibroblast growth factor(bFGFeye drops and hydroxyl indican eye drops on the tear film stability and dry eye symptoms after age-related cataract surgery. METHODS: A total of 115 patients(115 affected eyeswith dry eyes after age-related cataract surgery were divided into the bFGF group, the hydroxyl indican group and the blank control group by the random number table method. The blank control group was only given routine anti-inflammatory treatment, and on the basis, the bFGF group and the hydroxyl indican group were treated with bFGF eye drops and hydroxyl indican eye drops respectively. The clinical efficacy, adverse reactions, changes in scores of dry eye symptoms, Schirmer test(SⅠt, tear film break-up time(BUTand corneal fluorescein staining(CFSscores at different time points were compared among the three groups. RESULTS: The total markedly effective rates in the bFGF group(89.5%was higher than that in the hydroxyl indican group(70.3%or the blank control group(47.5%(PPPCONCLUSION: The tear film is unstable in early stage after age-related cataract surgery, and there are dry eye symptoms. The intervention with bFGF eye drops and hydroxyl indican eye drops can effectively restore the tear film stability and significantly relieve dry eye symptoms, and the effect of bFGF eye drops is more significant.

  8. Corneal sensitivity, ocular surface health and tear film stability after punctal plug therapy of aqueous deficient dry eye

    Directory of Open Access Journals (Sweden)

    Azza Mohamed Ahmed Said

    2016-11-01

    Full Text Available AIM: To evaluate the effect of punctal occlusion using thermosensitive (smart plug versus silicone plug for management of aqueous deficient dry eye on corneal sensitivity, ocular surface health and tear film stability. METHODS: A comparative prospective interventional case study included 45 patients with bilateral severe form of aqueous deficient dry eye. In each patient, the smart plug was inserted in the lower punctum of the right eye which was considered as study group 1 and silicone plug was inserted in the lower punctum of the left eye of the same patient which was considered as study group 2. All patients were subjected to careful history taking and questionnaire for subjective assessment of severity of symptoms. Corneal sensitivity, corneal fluorescein, rose bengal staining, Schirmer’s I test, tear film break up time and conjunctival impression cytology were performed pre and 1, 3 and 6mo post plug insertion. RESULTS: A statistically significant improvement in subjective and objective manifestations occurred following treatment with both types of plugs (P<0.01. The thermosensitive plug caused significant overall improvement, decrease in frequency of application of tear substitutes and improvement of conjunctival impression cytology parameters in the inserted side (P<0.01. Canaliculitis was reported in two eyes (4.4% following punctal occlusion using thermosensitive plug (study group 1. Spontaneous plug loss occurred in 21 eyes (46.6% in the silicone plug group (study group 2. CONCLUSION: Improvement of subjective and objective manifestations of aqueous deficient dry eye occurs following punctal plug occlusion. Thermosensitive plug has good patient's compliance with fewer complications and lower rates of loss compared to the silicone plug.

  9. A layer model of ethanol partitioning into lipid membranes.

    Science.gov (United States)

    Nizza, David T; Gawrisch, Klaus

    2009-06-01

    The effect of membrane composition on ethanol partitioning into lipid bilayers was assessed by headspace gas chromatography. A series of model membranes with different compositions have been investigated. Membranes were exposed to a physiological ethanol concentration of 20 mmol/l. The concentration of membranes was 20 wt% which roughly corresponds to values found in tissue. Partitioning depended on the chemical nature of polar groups at the lipid/water interface. Compared to phosphatidylcholine, lipids with headgroups containing phosphatidylglycerol, phosphatidylserine, and sphingomyelin showed enhanced partitioning while headgroups containing phosphatidylethanolamine resulted in a lower partition coefficient. The molar partition coefficient was independent of a membrane's hydrophobic volume. This observation is in agreement with our previously published NMR results which showed that ethanol resides almost exclusively within the membrane/water interface. At an ethanol concentration of 20 mmol/l in water, ethanol concentrations at the lipid/water interface are in the range from 30-15 mmol/l, corresponding to one ethanol molecule per 100-200 lipids.

  10. Engineering the lipid layer of lipid-PLGA hybrid nanoparticles for enhanced in vitro cellular uptake and improved stability.

    Science.gov (United States)

    Hu, Yun; Hoerle, Reece; Ehrich, Marion; Zhang, Chenming

    2015-12-01

    Lipid-polymer hybrid nanoparticles (NPs), consisting of a polymeric core and a lipid shell, have been intensively examined as delivery systems for cancer drugs, imaging agents, and vaccines. For applications in vaccine particularly, the hybrid NPs need to be able to protect the enclosed antigens during circulation, easily be up-taken by dendritic cells, and possess good stability for prolonged storage. However, the influence of lipid composition on the performance of hybrid NPs has not been well studied. In this study, we demonstrate that higher concentrations of cholesterol in the lipid layer enable slower and more controlled antigen release from lipid-poly(lactide-co-glycolide) acid (lipid-PLGA) NPs in human serum and phosphate buffered saline (PBS). Higher concentrations of cholesterol also promoted in vitro cellular uptake of hybrid NPs, improved the stability of the lipid layer, and protected the integrity of the hybrid structure during long-term storage. However, stabilized hybrid structures of high cholesterol content tended to fuse with each other during storage, resulting in significant size increase and lowered cellular uptake. Additional experiments demonstrated that PEGylation of NPs could effectively minimize fusion-caused size increase after long term storage, leading to improved cellular uptake, although excessive PEGylation will not be beneficial and led to reduced improvement. This paper reports the engineering of the lipid layer that encloses a polymeric nanoparticle, which can be used as a carrier for drug and vaccine molecules for targeted delivery. We demonstrated that the concentration of cholesterol is critical for the stability and uptake of the hybrid nanoparticles by dendritic cells, a targeted cell for the delivery of immune effector molecules. However, we found that hybrid nanoparticles with high cholesterol concentration tend to fuse during storage resulting in larger particles with decreased cellular uptake. This problem is

  11. Lipid peroxidation is increased in tears from the elderly.

    Science.gov (United States)

    Benlloch-Navarro, Soledad; Franco, Ilenia; Sánchez-Vallejo, Violeta; Silvestre, Dolores; Romero, Francisco Javier; Miranda, María

    2013-10-01

    We describe a procedure in which tears, obtained from Schirmer strips, are used to measure a marker of lipid peroxidation, malondialdehyde (MDA). We also compared the levels of proteins and MDA in tears from two groups of people: young adults (18-30 years old) and elderly adults (65-85 years old), because the data related to total protein concentration of human tears vary widely and because the majority of people over the age of 65 experience some symptoms of dry eyes and this condition has been recognized as an oxidative stress-induced disease. Our results show a significant difference in the protein concentration of the tears taken from the two age categories, younger adults (18-30 years old) and older adults (65-85 years old). Herein, we report for the first time an increase in MDA concentrations determined by HPLC in human tears based on age. It is possible that alterations in the tear lipid layer may lead to an increase in lipid peroxidation. Further studies are needed to understand the nature and function of tear film and stability in order to obtain new methods to analyze tears in patients with different diseases. In this sense, it would be interesting to compare MDA concentration in tears from control subjects and from people with meibomian gland dysfunction. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Effect of laser in situ keratomileusis with corneal flap created by femtosecond laser on tear film detected by Keratograph in different age groups

    Directory of Open Access Journals (Sweden)

    Yu-Xia Zhang

    2016-03-01

    Full Text Available AIM:To explore the changes of tear film detected by Keratograph in the patients after laser in situ keratomileusis(LASIKwith corneal flap created by femtosecond laser. METHODS: Totally 75 myopic patients(150 eyeswere enrolled who underwent femtosecond laser LASIK from July 2014 to June 2015, including patientsRESULTS: Before surgeries, the dry eye symptoms score of three groups had no significant difference(P>0.05. After surgeries, there were significant difference at each follow-up time among the three groups on symptoms score(PPCONCLUSION: LASIK can affect the dry eye symptoms and the stability of tear film, which decreased by postoperative time. And the index recovered to preoperative levels earlier in younger patients.

  13. Effect of diquafosol three per cent ophthalmic solution on tear film and corneal aberrations after cataract surgery.

    Science.gov (United States)

    Lee, Hun; Kim, Sang Myung; Choi, Seonghee; Seo, Kyoung Yul; Kim, Eung Kweon; Kim, Tae-Im

    2017-11-01

    The aim was to evaluate the effect of diquafosol on tear film parameters and corneal aberrations after cataract surgery. This retrospective, comparative, observational case series included patients who underwent cataract surgery with or without peri-operative use of diquafosol three per cent ophthalmic solution. Patients in group I (31 eyes) were treated with diquafosol three per cent ophthalmic solution six times a day from one week before surgery to three months after surgery. Patients in group II (33 eyes) underwent cataract surgery without being administered diquafosol. Tear film break-up time (BUT), the ocular surface disease index (OSDI), the Oxford Scheme score, Schirmer's test I and corneal aberrations were determined before and at one and three months post-surgery. In group I, the BUT, OSDI and Oxford Scheme score showed significant improvement at one and three months post-surgery (p = 0.002 for BUT at one month and three months, p = 0.023 and p = 0.049 for OSDI at one month and three months and p = 0.001 and p = 0.026 for Oxford Scheme at one month and three months), compared to baseline. In group II, the BUT, OSDI and Oxford Scheme score did not show any significant improvement during the follow-up period. In both groups, Schirmer's test I significantly decreased at three months post-surgery (p = 0.011 for group I and p = 0.034 for group II), compared to baseline. There were significant differences in the BUT and OSDI between the groups at three months post-surgery (p = 0.037 for BUT and p = 0.011 for OSDI). Regarding the corneal aberration, there were no significant differences between the groups at three months post-surgery. Peri-operative application of diquafosol three per cent ophthalmic solution may prevent dry eye-related ocular surface changes accompanied by improvement of ocular symptom. No definite changes in corneal aberrations were noted. © 2017 Optometry Australia.

  14. Changes in wetting and energetic properties of glass caused by deposition of different lipid layers

    Energy Technology Data Exchange (ETDEWEB)

    Golabek, Monika [Department of Physical Chemistry - Interfacial Phenomena, Faculty of Chemistry, Maria-Curie Sklodowska University, 20-031 Lublin (Poland); Holysz, Lucyna, E-mail: lucyna.holysz@poczta.umcs.lublin.pl [Department of Physical Chemistry - Interfacial Phenomena, Faculty of Chemistry, Maria-Curie Sklodowska University, 20-031 Lublin (Poland)

    2010-06-15

    An investigation of wetting and energetic properties of different lipid layers deposited on the glass surface was carried out by contact angles measurements and determination of the apparent surface free energy. The topography of the lipid layers was also determined with the help of atomic force microscopy (AFM). Two synthetic phospholipids were chosen for these studies, having the same phosphatidylcholine headgroup bound to the apolar part composed either by two saturated chains (1,2-dipalmitoyl-sn-glycero-3-phospshocholine - DPPC) or two unsaturated chains (1,2-dioleoyl-sn-glycero-3-phosphocholine - DOPC) and one lipid (1,2,3-trihexadecanoyl-sn-glycerol - tripalmitoylglycerol - TPG). The lipid layers, from the 1st to the 5th statistical monolayer, were deposited on the glass surface from chloroform solutions by spreading. The apparent surface free energy of the deposited layers was determined by contact angles measurements (advancing and receding) for three probe liquids (diiodomethane, water, and formamide), and then two concepts of interfacial interactions were applied. In the contact angle hysteresis approach (CAH) the apparent total surface free energy was calculated from the advancing and receding contact angles and surface tension of probe liquids. In the Lifshitz-van der Waals/acid-base approach (LWAB) the total surface free energy was calculated from the determined components of the energy, which were obtained from the advancing contact angles of the probe liquids only. Comparison of the results obtained by two approaches provided more information about the changes in the hydrophobicity/hydrophilicity of the layers depending on the number of monolayers and kind of the lipid deposited on the glass surface. It was found that the most visible changes in the surface free energy took place for the first two statistical monolayers irrespectively of the kind of the lipid used. Additionally, in all cases periodic oscillations from layer-to-layer in the lipid

  15. Effect of vitamin A palmitate ophthalmic gel adjunctive therapy on tear film stability and inflammatory cytokines in patients with dry eye

    Directory of Open Access Journals (Sweden)

    Ya-Yuan Lu

    2018-06-01

    Full Text Available AIM:To investigate the effect of sodium hyaluronate eye drops combined with vitamin A palmitate ophthalmic gel on levels of tear film stability and inflammatory cytokines in patients with dry eye. METHODS: A total of 100 patients with dry eye treated in our hospital from January 2015 to February 2017 were randomly divided into control group and observation group, 50 cases in each group. Patients in the control group were treated with sodium hyaluronate eye drops. Patients in the observation group were given vitamin A palmitate ophthalmic gel on the basis of the control group, and then the clinical efficacy, tear film stability and the level of inflammatory cytokines were detected in the two groups. RESULTS: After treatment, the levels of BUT and SⅠt in both groups increased significantly compared with that before treatment, and FL was significantly lower than that before treatment. The levels of BUT and SⅠt in the observation group after treatment were 11.24±0.22s and 11.4±0.17mm/5min respectively, which was high than that of control groups(PPPPCONCLUSION: Sodium hyaluronate eye drops combined with vitamin A palmitate ophthalmic gel can relieve the symptoms of patients with dry eye effectively, increase the stability of tear film, and reduce the levels of inflammatory factors in tears, which is reliable in clinical application.

  16. Dysfunctional tear syndrome: dry eye disease and associated tear film disorders – new strategies for diagnosis and treatment

    Science.gov (United States)

    Milner, Mark S.; Beckman, Kenneth A.; Luchs, Jodi I.; Allen, Quentin B.; Awdeh, Richard M.; Berdahl, John; Boland, Thomas S.; Buznego, Carlos; Gira, Joseph P.; Goldberg, Damien F.; Goldman, David; Goyal, Raj K.; Jackson, Mitchell A.; Katz, James; Kim, Terry; Majmudar, Parag A.; Malhotra, Ranjan P.; McDonald, Marguerite B.; Rajpal, Rajesh K.; Raviv, Tal; Rowen, Sheri; Shamie, Neda; Solomon, Jonathan D.; Stonecipher, Karl; Tauber, Shachar; Trattler, William; Walter, Keith A.; Waring, George O.; Weinstock, Robert J.; Wiley, William F.; Yeu, Elizabeth

    2017-01-01

    Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition. PMID:28099212

  17. Dysfunctional tear syndrome: dry eye disease and associated tear film disorders - new strategies for diagnosis and treatment.

    Science.gov (United States)

    Milner, Mark S; Beckman, Kenneth A; Luchs, Jodi I; Allen, Quentin B; Awdeh, Richard M; Berdahl, John; Boland, Thomas S; Buznego, Carlos; Gira, Joseph P; Goldberg, Damien F; Goldman, David; Goyal, Raj K; Jackson, Mitchell A; Katz, James; Kim, Terry; Majmudar, Parag A; Malhotra, Ranjan P; McDonald, Marguerite B; Rajpal, Rajesh K; Raviv, Tal; Rowen, Sheri; Shamie, Neda; Solomon, Jonathan D; Stonecipher, Karl; Tauber, Shachar; Trattler, William; Walter, Keith A; Waring, George O; Weinstock, Robert J; Wiley, William F; Yeu, Elizabeth

    2017-01-01

    Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition.

  18. Thin-Layer Chromatography/Desorption Atmospheric Pressure Photoionization Orbitrap Mass Spectrometry of Lipids

    Czech Academy of Sciences Publication Activity Database

    Rejšek, Jan; Vrkoslav, Vladimír; Vaikkinen, A.; Haapala, M.; Kauppila, T. J.; Kostiainen, R.; Cvačka, Josef

    2016-01-01

    Roč. 88, č. 24 (2016), s. 12279-12286 ISSN 0003-2700 R&D Projects: GA ČR GAP206/12/0750 Institutional support: RVO:61388963 Keywords : desorption atmospheric pressure photoionization * thin-layer chromatography * lipids Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 6.320, year: 2016

  19. Potential and limitations of S-layers as support for planar lipid bilayers

    International Nuclear Information System (INIS)

    Kiene, E.

    2011-01-01

    A huge step in the development of life was most certainly the formation of lipid membranes and the resulting possibility for generating confined volumes, structurally discrete from the environment. Yet, communication had to be maintained with the outside world, so these membrane borders were populated with functional units, like membrane receptors and transporters, enabling the exchange of material, energy and information. Therefore, from a scientific point of view, the requirement for analysis platforms for membrane proteins incorporated into model membrane scaffolds emerged. The membrane systems hosting arbitrary membrane proteins are desired to unite the features of stability and fluidity and to provide a quasi natural environment for the membrane proteins in order to maintain their structure and function. In the current state of the art there are hardly any relevant fluid membrane models, which is why in this project a prokaryotic protein-lipid architecture was mimicked as a promising supportive system for biological membranes. A large number of bacteria and archaea envelope their outer cell membrane with a proteinaceous lattice, the so-called surface- or S-layer. The present work deals with S-layer protein lattices as a support for anchored lipid bilayers. S-layer proteins show the intrinsic ability to self-assemble into periodically structured, two-dimensional patterns with a porous character. Genetic or chemical modification of the proteinaceous crystal layers can provide regularly spread binding moieties for functionalised lipids as components of a lipid membrane. In this project, a wildtype S-layer (SbpA from L. sphaericus exhibiting p4 lattice symmetry) was chemically activated to provide anchors for amino-functionalised lipids; and in a genetic approach a recombinant, HIS-tagged derivative was used for attracting Ni-functionalised lipids. The latter method seemed a more elegant way of lipid binding, since the anchoring regions were more regularly spread

  20. Novel Nano-Liposome Formulation for Dry Eyes with Components Similar to the Preocular Tear Film

    Directory of Open Access Journals (Sweden)

    Marta Vicario-de-la-Torre

    2018-04-01

    Full Text Available Dry eye is commonly treated with artificial tears; however, developing artificial tears similar to natural tears is difficult due to the complex nature of tears. We characterized and evaluated a novel artificial tear formulation with components similar to the lipid and aqueous constituents of natural tears. Nano-liposomes, composed in part of phosphatidylcholine, were dispersed in an aqueous solution of bioadhesive sodium hyaluronate. Liposome size, zeta potential, and physicochemical properties of the fresh and stored (4 °C liposomal formulation were analyzed. In vitro tolerance was tested using human corneal and conjunctival cell lines by exposures of 15 min to 4 h. The tolerance of the liposomal formulation was evaluated in animals (rabbits. The average liposome size was 186.3 ± 7.0 nm, and the zeta potential was negative. The osmolarity of the formulation was 198.6 ± 1.7 mOsm, with a surface tension of 36.5 ± 0.4 mN/m and viscosity of 3.05 ± 0.02 mPa·s. Viability values in the human corneal and conjunctival cell lines were always >80%, even after liposomal formulation storage for 8 weeks. Discomfort and clinical signs after instillation in rabbit eyes were absent. The new formulation, based on phosphatidylcholine-liposomes dispersed in sodium hyaluronate has suitable components and characteristics, including high in vitro cell viability and good in vivo tolerance, to serve as a tear substitute.

  1. Lipids from the nacreous and prismatic layers of two Pteriomorpha Mollusc shells

    Science.gov (United States)

    Farre, B.; Dauphin, Y.

    2009-04-01

    Mollusc shells are the best-known Ca-carbonate biominerals. They are commonly described as a mineralized two layered structure: an outer layer composed of calcite prismatic units, and an internal layer composed of tablets of aragonite: the nacreous layer. An external organic layer (periostracum) is present in most taxa. However, the most common structure in the Mollusc shell is the aragonite crossed lamellar layer, but aragonite prisms, calcite foliated layers and homogeneous layers have been also described by Boggild (1930) in all the Mollusc orders. Since, more detailed descriptions of Bivalve shells have been done (Taylor et al., 1969, 1973). Despite the nacroprismatic arrangement is rare, calcite prismatic and aragonite nacreous layers are the best studied because of their simple 3D structure and large units. Among these Molluscs, some Bivalve species composed of these two layers are of commercial interest, such as the pearl oyster, Pinctada margaritifera, cultivated in French Polynesia to produce black pearls. It is well established that Mollusc shells are composite structures of organic and inorganic components (Hatchett, 1799; Grégoire et al., 1955; Beedham, 1958; Simkiss, 1965; Mutvei, 1969; Cuif et al., 1980; Berman et al., 1993; Kobayashi and Samata, 2006). Numerous studies are concerned with the organic matrix of the shell. Organic components are commonly obtained after a strong or mild decalcification process. They are said to consist of both a soluble and insoluble fraction. The main part of studies is dedicated to the soluble components, and among them, proteins (Grégoire et al., 1955; Grégoire, 1961; Krampitz et al., 1976; Samata et al., 1980, 2004; Weiner, 1983; Miyamoto et al., 2006). Despite the pioneering work of Wada (1980) sugars are usually neglected despite their role in biomineralization. The third component of the organic matrix of calcareous biominerals is lipids. To date, there is a paucity of information concerning the presence

  2. Effect of rb-bFGF eye drops and hydroxyl indican eye drops on tear film stability and dry eye symptoms after age-related cataract surgery

    Directory of Open Access Journals (Sweden)

    Yu Ling

    2018-01-01

    Full Text Available AIM: To investigate the effect of recombinant bovine basic fibroblast growth factor(rb-bFGFeye drops and hydroxyl indican eye drops on tear film stability and dry eye symptoms after age-related cataract surgery. METHODS: Totally 80 patients with 80 affected eyes undergoing age-related cataract surgery in our hospital from January 2015 to October 2016 were selected as study subjects, and they were randomly divided into control group and experimental group with 40 patients(40 affected eyesin each group. The two groups were treated with hydroxyl indican eye drops and rb-bFGF eye drops, respectively. The clinical curative effect, inflammation related factors \\〖interleukin 6(IL-6, tumor necrosis factor α(TNF-α\\〗, Schirmer test(SⅠt, break-up time(BUTof tear film, corneal sodium fluorescein staining(FLand scores of dry eye symptoms in the two groups were observed. RESULTS: The total treatment effective rate of experimental group after treatment was significantly higher than that of the control group(90.0% vs 72.5%; χ2=4.021, PP>0.05. After treatment, IL-6, TNF-α, SⅠt, FL score and scores of dry eye symptoms in two groups significantly decreased while BUT significantly increased(PPCONCLUSION: In the treatment of patients after age-related cataract after surgery, rb-bFGF eye drops has more advantages over hydroxyl indican eye drops in regulating the expression of inflammatory factors, improving the tear film stability and relieving dry eye symptoms.

  3. Development of "all natural" layer-by-layer redispersible solid lipid nanoparticles by nano spray drying technology.

    Science.gov (United States)

    Wang, Taoran; Hu, Qiaobin; Zhou, Mingyong; Xia, Yan; Nieh, Mu-Ping; Luo, Yangchao

    2016-10-01

    Solid lipid nanoparticles (SLNs) have gained tremendous attraction as carriers for controlled drug delivery. Despite numerous advances in the field, one long-standing historical challenge for their practical applications remains unmet: redispersibility after drying. In this work, a novel design of SLNs using a layer-by-layer (LbL) technique was developed and the formulations were optimized by surface response methodology (Box-Behnken design). To the best of our knowledge, this is the first study reporting the fabrication of SLNs from all natural ingredients in the absence of any synthetic surfactants or coatings. The SLNs were prepared by a combined solvent-diffusion and hot homogenization method, with soy lecithin as natural emulsifier (first layer), followed by the subsequent coating with sodium caseinate (second layer) and pectin (third layer), both of which are natural food biopolymers. The adsorption of pectin coating onto caseinate was reinforced by hydrophobic and electrostatic interactions induced by a pH-driven process along with thermal treatment. The innovative nano spray drying technology was further explored to obtain ultra-fine powders of SLNs. Compared to uncoated or single-layer coated SLNs powders, which showed severe aggregation after spray drying, the well-separated particles with spherical shape and smooth surface were obtained for layer-by-layer (LbL) SLNs, which were redispersible into water without variation of dimension, shape and morphology. The SLNs were characterized by Fourier transform infrared and high-performance differential scanning calorimetry for their physical properties. The LbL-coated SLNs based on all natural ingredients have promising features for future applications as drug delivery systems, overcoming the major obstacles in conventional spray drying and redispersing SLNs-based formulations. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Ocular surface and tear film status among contact lens wearers and non-wearers who use VDT at work: comparing three different lens types.

    Science.gov (United States)

    Tauste, Ana; Ronda, Elena; Baste, Valborg; Bråtveit, Magne; Moen, Bente E; Seguí Crespo, María-Del-Mar

    2018-04-01

    To analyze differences in the ocular surface appearance and tear film status of contact lens wearers and non-wearers in a group of visual display terminals (VDT) workers and additionally to assess differences between lens materials. Cross-sectional study of 236 office workers, of whom 92 were contact lens wearers. Workers provided information on their contact lenses (conventional hydrogel, silicone hydrogel or rigid gas permeable lenses) and exposure to VDT at work. Ocular surface and tear film status were determined by the presence of bulbar, limbal and lid redness, lid roughness and corneal staining type, and by Schirmer's and tear break-up time tests (TBUT). A generalized linear model was used to calculate the crude (cRR) and age- and sex-adjusted (aRR) relative risk to measure the association between ocular surface and tear film abnormalities and contact lens use and type. The aRR of ocular surface abnormalities was higher in contact lens wearers compared to non-wearers: bulbar redness (aRR 1.69; 95% CI 1.25-2.30), limbal redness (aRR 2.87; 1.88-4.37), lid redness (aRR 2.53; 1.35-4.73) and lid roughness (aRR 7.03; 1.31-37.82). VDT exposure > 4 h/day increased wearers' risk of limbal and lid redness. Conventional hydrogel wearers had the highest risk of ocular surface abnormalities, followed by silicone hydrogel wearers. Both contact and non-contact lens wearers had a high prevalence of altered TBUT (77.3 and 75.7% respectively) and Schirmer (51.8 and 41.3%). Regular contact lens use during VDT exposure at work increases risk of bulbar, limbal and lid redness, and lid roughness, especially in soft contact lens wearers. The high prevalence of altered TBUT and Schirmer's results in all participants suggests that VDT use greatly affects tear film characteristics.

  5. EFFECT OF FEEDING CANOLA AND SOYBEAN OILS ON SERUM LIPID PROFILE IN COMMERCIAL LAYERS

    Directory of Open Access Journals (Sweden)

    Shakoor. H. I., M. L. Khan, Z. Nasir, N. Mukhtar and M. S. Rehman

    2002-04-01

    Full Text Available The purpose of this study was to assess the effect of canola oil and soybean oil on production performance and serum lipid profile in layers. In this study 15 experimental units (8 layers per experimental unit were randomly allotted to 5 different dietary treatments viz control (A. containing 2.5 % canola oil (B, 5% canola oil (C, 2.5% soybean oil (D and 5% soybean oil (E for a period of 9 weeks. Effects of five treatments on production parameters including egg production, egg quality, weight gain and serum lipid profile, serum cholesterol, triglycerides, low-density lipoprotein and high-density lipoprotein were monitored. Serum lipid profile was determined 0.31 and 63 days from start of experiment. Significantly (P<0.05 less serum cholesterol was found in treatment C (295.1 mg/dl as compared with treatment A (321 mg/dl. Low density lipoprotein cholesterol (LDL was significantly (P<0.01 , less in treatment C ( 131.7 mg/dl as compared with treatment A. ( 161 mg/dl and high density lipoprotein cholesterol (HDL was significantly (P<0.01 high in treatment C (31.76 mg/dl as compared with treatment A (25.42 mg/dl and triglyceride (TG was found significantly (P<0.01 less in treatment E ( 907.3 mg/dl as compared with treatment A (960 mg/dl. The results suggested that as the percentage of oils increased in the diet, serum lipid profile showed a positive trend.

  6. Intraspecific differences in lipid content of calanoid copepods across fine-scale depth ranges within the photic layer.

    Directory of Open Access Journals (Sweden)

    Margarita Zarubin

    Full Text Available Copepods are among the most abundant and diverse groups of mesozooplankton in the world's oceans. Each species has a certain depth range within which different individuals (of the same life stage and sex are found. Lipids are accumulated in many calanoid copepods for energy storage and reproduction. Lipid content in some species increases with depth, however studies so far focused mostly on temperate and high-latitude seasonal vertically migrating copepods and compared lipid contents among individuals either from coarse layers or between diapausing, deep-dwelling copepods and individuals found in the photic, near-surface layer. Here we examined whether lipid contents of individual calanoid copepods of the same species, life stage/sex differ between finer depth layers within the upper water column of subtropical and Arctic seas. A total of 6 calanoid species were collected from samples taken at precise depths within the photic layer in both cold eutrophic and warm oligotrophic environments using SCUBA diving, MOCNESS and Multinet. Measurements of lipid content were obtained from digitized photographs of the collected individuals. The results revealed significant differences in lipid content across depth differences as small as 12-15 meters for Mecynocera clausi C5 and Ctenocalanus vanus C5 (Red Sea, Clausocalanus furcatus males and two clausocalanid C5s (Mediterranean Sea, and Calanus glacialis C5 (Arctic. We suggest two possible explanations for the differences in lipid content with depth on such a fine scale: predator avoidance and buoyancy.

  7. Profiling the triacylglyceride contents in bat integumentary lipids by preparative thin layer chromatography and MALDI-TOF mass spectrometry.

    Science.gov (United States)

    Pannkuk, Evan L; Risch, Thomas S; Savary, Brett J

    2013-09-05

    The mammalian integument includes sebaceous glands that secrete an oily material onto the skin surface. Sebum production is part of the innate immune system that is protective against pathogenic microbes. Abnormal sebum production and chemical composition are also a clinical symptom of specific skin diseases. Sebum contains a complex mixture of lipids, including triacylglycerides, which is species-specific. The broad chemical properties exhibited by diverse lipid classes hinder the specific determination of sebum composition. Analytical techniques for lipids typically require chemical derivatizations that are labor-intensive and increase sample preparation costs. This paper describes how to extract lipids from mammalian integument, separate broad lipid classes by thin-layer chromatography, and profile the triacylglyceride contents using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This robust method enables a direct determination of the triacylglyceride profiles among species and individuals, and it can be readily applied to any taxonomic group of mammals.

  8. Interactions of poly(tert-butyl acrylate)-poly(styrene) diblock copolymers with lipids at the air-water interface.

    Science.gov (United States)

    Mudgil, Poonam; Dennis, Gary R; Millar, Thomas J

    2006-08-29

    Diblock copolymers with hydrophilic poly(tert-butyl acrylate) (PtBA) and hydrophobic poly(styrene) (PS) blocks were synthesized with a view to use them as a surfactant in tear film for increasing the ocular comfort in dry eye syndrome. Interactions of six PtBA-PS copolymers with four important lipids found in the tear film, namely cholesterol, cholesteryl palmitate, dipalmitoyl phosphatidylcholine, and phosphatidylinositol, were studied at the air-water interface using a Langmuir trough. Thermodynamics of mixing of the copolymers and the lipids in the mixed monolayers was determined by calculating excess free energy of mixing. The diblock copolymers showed repulsive interactions with cholesteol and cholesteryl palmitate, near neutral interactions with dipalmitoyl phosphatidylcholine, and attractive interactions with phosphatidylinositol. The lipids interacted with the PS component of the copolymer. The results indicate that a copolymer with a small hydrophilic group and a big hydrophobic group can be a likely candidate for forming stable interactions with the lipids present in the tear film and hence increase the ocular comfort.

  9. Ocular symptoms and tear film break up time (BUT) among junior high school students in Penang, Malaysia - Associations with fungal DNA in school dust.

    Science.gov (United States)

    Norbäck, Dan; Hashim, Jamal Hisham; Hashim, Zailina; Sooria, Vinoshini; Ismail, Syazwan Aizat; Wieslander, Gunilla

    2017-06-01

    There are few studies on ocular effects of indoor mould exposure in schools, especially in the tropics OBJECTIVE: To study associations between eye symptoms and tear film break up time (BUT) in students and demographic data and fungal DNA in schools. A school environment study was performed among randomly selected students in eight randomly selected secondary schools in Penang, Malaysia. Information on eye symptoms and demographic data was collected by a standardised questionnaire. BUT was measured by two methods, self-reported BUT (SBUT) and by the non-invasive Tearscope (NIBUT). Dust was collected by vacuuming in 32 classrooms and analysed for five fungal DNA sequences. Geometric mean (GM) for total fungal DNA was 7.31*10 4 target copies per gram dust and for Aspergillus/Penicillium DNA 3.34*10 4 target copies per gram dust. Linear mixed models and 3-level multiple logistic regression were applied adjusting for demographic factors. A total of 368 students (58%) participated and 17.4% reported weekly eye symptoms the last 3 months. The median SBUT and TBUT were 15 and 12s, respectively. Students wearing glasses (OR 2.41, p=0.01) and with a history of atopy (OR=2.67; p=0.008) had more eye symptoms. Girls had less eye symptoms than boys (OR=0.34; p=0.006) Indoor carbon dioxide in the classrooms was low (range 380-720ppm), temperature was 25-30°C and relative air humidity 70-88%. Total fungal DNA in vacuumed dust was associated with shorter SBUT (4s shorter per 10 5 target copies per gram dust; p=0.04) and NIBUT (4s shorter per 10 5 target copies per gram dust; p<0.001). Aspergillus/Penicillium DNA was associated with shorter NIBUT (5s shorter per 10 5 target copies per gram dust; p=0.01). Fungal contamination in schools in a tropical country can be a risk factor for impaired tear film stability among students. Copyright © 2017 Elsevier GmbH. All rights reserved.

  10. Short-term effect of topical antiglaucoma medication on tear-film stability, tear secretion, and corneal sensitivity in healthy subjects.

    Science.gov (United States)

    Terai, Naim; Müller-Holz, Matthias; Spoerl, Eberhard; Pillunat, Lutz E

    2011-01-01

    The purpose of this study was to investigate the short-term effect of topical antiglaucoma medication on tear-film stability, tear secretion, and corneal sensitivity in healthy subjects. In this prospective, double-blind crossover trial, break-up time and basal secretion (Jones test) were measured 60 minutes before, and 30, 60, and 90 minutes after topical antiglaucoma drop application in 30 healthy subjects. Corneal sensitivity was measured 60 minutes before, and five, 10, and 15 minutes after drop application using a Cochet-Bonnet esthesiometer. Reduction of break-up time in the latanoprost group was -23.8% after 30 minutes (P = 0.21), -26.7% after 60 minutes (P = 0.03) and -51.4% after 90 minutes (P ≤ 0.003), which was statistically significant. Reduction of break-up time in all other treatment groups was not statistically significant. The Jones test revealed a significant reduction of basal secretion after application of brimonidine (-17.8%, P = 0.002; -22.5%, P < 0.001; -30.5%, P < 0.001), followed by apraclonidine (-10%, P = 0.06; -20.1%, P = 0.02; -22.1%, P = 0.002), latanoprost (-2.4%, P = 0.64; -18.6%, P = 0.001; -20.1%, P = 0.001) and dorzolamide (-0.5%, P = 0.9; 14.3%, P = 0.018; -17.3%, P = 0.004) at 30, 60, and 90 minutes after drop application. Reduction of basal secretion in all other treatment groups was not statistically significant. Latanoprost showed the most statistically significant reduction in break-up time, and brimonidine showed the most significant reduction in basal secretion of all the glaucoma medications used in this study. In conclusion, our data may be helpful for treatment decisions in glaucoma patients who also suffer from ocular surface problems.

  11. Changes in the evaporation rate of tear film after digital expression of meibomian glands in patients with and without dry eye.

    Science.gov (United States)

    Arciniega, Juan Carlos; Wojtowicz, Jadwiga Cristina; Mohamed, Engy Mostafa; McCulley, James Parker

    2011-08-01

    To evaluate the effect of excess meibum on tear evaporation rate in patients with and without dry eye. Eleven healthy subjects and 16 patients with dry eye were tested. The dry eye group was divided into 2 subgroups: classic keratoconjunctivitis sicca (KCS) with clear and easily expressed meibum and KCS with meibomian gland dysfunction (MGD) with turbid secretions and difficult-to-express meibum. Evaporative measurements were performed at baseline and after digital expression of meibomian glands at 12, 24, 36, and 48 minutes. Two ranges of relative humidity were used, 25% to 35% and 35% to 45%. The data were expressed as microliters per square centimeter per minute. An increase in the evaporation rate of the tear film was noted for all measurements at both relative humidities in the classic KCS and KCS with MGD groups compared with healthy subjects (P evaporation rates at relative humidities of 25% to 35% and 35% to 45% were 0.056 ± 0.016 and 0.040 ± 0.008 for the classic KCS group; 0.055 ± 0.026 and 0.037 ± 0.019 for the KCS with MGD group and 0.033 ± 0.012 and 0.023 ± 0.008 for the healthy group. Also, a decrease in the evaporation rate was observed in the healthy and KCS with MGD groups between baseline and the first measurement after digital expression for both relative humidities (P evaporation rates compared with the healthy group. Aqueous tear evaporation diminished in the healthy and KCS with MGD groups after expression of meibomian glands. However, this effect was transient and negligible after the second measurement.

  12. Comparison of novel lipid-based eye drops with aqueous eye drops for dry eye: a multicenter, randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Simmons PA

    2015-04-01

    and aqueous eye drops. The results suggest that lipid-containing artificial tears can be used to counteract lipid deficiency that is common in dry eye, without compromising overall acceptability. Keywords: artificial tears, emulsion, dry eye, Ocular Surface Disease Index, tear break-up time, tear film lipid layer

  13. The effect of dietary lipid sources on layer fertility and hatchability ...

    African Journals Online (AJOL)

    This study was conducted to investigate the effect of dietary fatty acids (FA) on the fertility and hatchability of laying hens at the end-of-lay period (69 - 77 weeks of age). Five isoenergetic (12.4 MJ ME/kg DM) and isonitrogenous (170 g CP/kg DM) diets were formulated using different lipid sources (30 g/kg inclusion) to ...

  14. Altered lipid metabolism in the aging kidney identified by three layered omic analysis.

    Science.gov (United States)

    Braun, Fabian; Rinschen, Markus M; Bartels, Valerie; Frommolt, Peter; Habermann, Bianca; Hoeijmakers, Jan H J; Schumacher, Björn; Dollé, Martijn E T; Müller, Roman-Ulrich; Benzing, Thomas; Schermer, Bernhard; Kurschat, Christine E

    2016-03-01

    Aging-associated diseases and their comorbidities affect the life of a constantly growing proportion of the population in developed countries. At the center of these comorbidities are changes of kidney structure and function as age-related chronic kidney disease predisposes to the development of cardiovascular diseases such as stroke, myocardial infarction or heart failure. To detect molecular mechanisms involved in kidney aging, we analyzed gene expression profiles of kidneys from adult and aged wild-type mice by transcriptomic, proteomic and targeted lipidomic methodologies. Interestingly, transcriptome and proteome analyses revealed differential expression of genes primarily involved in lipid metabolism and immune response. Additional lipidomic analyses uncovered significant age-related differences in the total amount of phosphatidylethanolamines, phosphatidylcholines and sphingomyelins as well as in subspecies of phosphatidylserines and ceramides with age. By integration of these datasets we identified Aldh1a1, a key enzyme in vitamin A metabolism specifically expressed in the medullary ascending limb, as one of the most prominent upregulated proteins in old kidneys. Moreover, ceramidase Asah1 was highly expressed in aged kidneys, consistent with a decrease in ceramide C16. In summary, our data suggest that changes in lipid metabolism are involved in the process of kidney aging and in the development of chronic kidney disease.

  15. Imaging the Tear Film: A Comparison Between the Subjective Keeler Tearscope-Plus™ and the Objective Oculus® Keratograph 5M and LipiView® Interferometer.

    Science.gov (United States)

    Markoulli, Maria; Duong, Tran Bao; Lin, Margaret; Papas, Eric

    2018-02-01

    To compare non-invasive break-up time (NIBUT) when measured with the Tearscope-Plus™ and the Oculus® Keratograph 5M, and to compare lipid layer thicknesses (LLT) when measured with the Tearscope-Plus™ and the LipiView®. This study also set out to establish the repeatability of these methods. The following measurements were taken from both eyes of 24 participants on two occasions: non-invasive keratograph break-up time using the Oculus® (NIKBUT-1 and NIKBUT-average), NIBUT using the Tearscope-Plus™, and LLT using the LipiView® (minimum, maximum, and average) and Tearscope-Plus™. The Tearscope-Plus™ grades were converted to nanometers. There were no significant differences between eyes (Tearscope-Plus™ NIBUT: p = 0.52; NIKBUT-1: p = 0.052; NIKBUT-average: p = 0.73; Tearscope-Plus™ LLT: p = 0.13; LipiView® average, maximum, or minimum: p = 0.68, 0.39 and 0.50, respectively) or days (Tearscope-Plus™ NIBUT: p = 0.32; NIKBUT-1: p = 0.65; NIKBUT-average: p = 0.54; Tearscope-Plus™ LLT: p = 0.26; LipiView® average, maximum, or minimum: p = 0.20, 0.09, and 0.10, respectively). LLT was significantly greater with the Tearscope-Plus™ (80.4 ± 34.0 nm) compared with the LipiView® average (56.3 ± 16.1 nm, p = 0.007), minimum (50.1 ± 15.8 nm, p < 0.001) but not maximum (67.2 ± 19.6 nm, p = 0.55). NIBUT was significantly greater with the Tearscope-Plus™ (15.9 ± 10.7 seconds) compared to the NIKBUT-1 (8.2 ± 3.5 seconds, p = 0.006) but not NIKBUT-average (10.9 ± 3.9 seconds, p = 0.08). The Tearscope-Plus™ is not interchangeable with either the Oculus® K5M measurement of tear stability (NIKBUT-1) or the LipiView® maximum and minimum lipid thickness.

  16. Kinetic Evaluation of Lipid Oils Conversion to Biofuel Using Layered Double Hydroxide Doped with Triazabicyclodece Catalyst

    Science.gov (United States)

    Nato Lopez, Frank D.

    Worldwide, there is an ever increasing need for sustainable, renewable fuels that will accommodate the rapidly increasing energy demand and provide independence from fossil fuels. The search for a sustainable alternative to petroleum based fuels has been a great challenge to the scientific community; therefore, great efforts are being made to overcome the fossil fuels dependence by exploring the prominent field of biofuels (bioethanol and biodiesel). Traditional biodiesel is produced from feedstocks such as vegetable oils and animal fats by converting the triglycerides with methanol in the presence of a homogeneous catalyst to produce fatty acid methyl esters (FAMEs). However, drawbacks of this process are the undesired glycerol byproduct and post reaction processing, including separation from reaction mixture, that results in high costs factors. In the present work, the reaction kinetics of a glycerol-free biodiesel method is studied. This method consists of the transesterification of a vegetable oil (i.e. canola oil) using dimethyl carbonate (DMC) as an alternative methylating agent in presence of layered double hydroxides doped with triazabicyclodecene catalyst (a basic organocatalyst). Furthermore, is theorized that this heterogeneous catalyst (TBD/LDH) simultaneously converts both FFAs and triglycerides due to acid sites formed by Al3+ active sites of the LDH structure. Additionally, the versatility of the Raman in situ technique was used as quantitative analysis tool to monitor the reaction kinetics and collect real time data.

  17. Ultrasound extraction and thin layer chromatography-flame ionization detection analysis of the lipid fraction in marine mucilage samples.

    Science.gov (United States)

    Mecozzi, M; Amici, M; Romanelli, G; Pietrantonio, E; Deluca, A

    2002-07-19

    This paper reports an analytical procedure based on ultrasound to extract lipids in marine mucilage samples. The experimental conditions of the ultrasound procedure (solvent and time) were identified by a FT-IR study performed on different standard samples of lipids and of a standard humic sample, before and after the sonication treatment. This study showed that diethyl ether was a more suitable solvent than methanol for the ultrasonic extraction of lipids from environmental samples because it allowed to minimize the possible oxidative modifications of lipids due to the acoustic cavitation phenomena. The optimized conditions were applied to the extraction of total lipid amount in marine mucilage samples and TLC-flame ionization detection analysis was used to identify the relevant lipid sub-fractions present in samples.

  18. Avaliação da microbiota ocular em pacientes com disfunção do filme lacrimal Evaluation of conjunctival flora in patients with tear film dysfunction

    Directory of Open Access Journals (Sweden)

    Melissa Megumi Tomimatsu

    2009-12-01

    Full Text Available OBJETIVO: Avaliar a microbiota conjuntival em olhos com disfunção do filme lacrimal, e a modificação desta microbiota após a colocação de plug de silicone no canalículo inferior. MÉTODOS: Série de casos intervencionais não comparativos para avaliar 68 olhos de 41 pacientes com disfunção do filme lacrimal, durante o período de 2002 a 2007, na Universidade Federal de São Paulo. Todos os pacientes foram submetidos à colheita de amostras de raspado conjuntival de fundo-de-saco inferior para cultivo em Brain heart infusion broth. Os vinte e dois pacientes submetidos à colocação de plug de silicone repetiram a colheita de raspado conjuntival um mês após o procedimento. RESULTADOS: Dos 68 olhos avaliados, 47 apresentaram crescimento bacteriano nas amostras colhidas. Nove diferentes espécies de bactérias foram identificadas: Staphylococcus coagulase negativa em 66,66%, Staphylococcus aureus em 13,72%, Corynebacterium sp em 5,86%, Enterobacter aerogenes em 3,92%, Streptococcus hemolítico do grupo viridans em 1,96%, Serratia sp em 1,96%, Alcaligenes xylosoxidans spp em 1,96%, Corynebacterium xerosis em 1,96%, e Proteus mirabilis em 1,96%. Staphylococcus coagulase negativa (SCN foi o microrganismo mais frequentemente isolado tanto antes quanto após o plug de silicone. A sensibilidade do SCN à Oxacilina antes da colocação do plug era de 87,50%, e, após, de 73,68%. CONCLUSÃO: A microbiota em olhos com disfunção do filme lacrimal é bastante semelhante à encontrada em olhos normais. A resistência de SCN à Oxacilina foi um pouco maior após o implante do plug de silicone.PURPOSE: To evaluate conjunctival microbiota in eyes with tear film dysfunction and its modification after punctal occlusion with silicone plug. METHODS: Non comparative interventional case series study to evaluate 68 eyes of 41 patients with tear film dysfunction, from 2002 to 2007, followed in Federal University of Sao Paulo. Samples for culture were all

  19. Combined thin layer chromatography and gas chromatography with mass spectrometric analysis of lipid classes and fatty acids in malnourished polar bears (Ursus maritimus) which swam to Iceland.

    Science.gov (United States)

    Eibler, Dorothee; Krüger, Sabine; Skírnisson, Karl; Vetter, Walter

    2017-03-01

    Between 2008 and 2011, four polar bears (Ursus maritimus) from the Greenland population swam and/or drifted on ice to Iceland where they arrived in very poor body condition. Body fat resources in these animals were only between 0% and 10% of the body weight (usually 25%). Here we studied the lipid composition in different tissues (adipose tissue if available, liver, kidney and muscle). Lipid classes were determined by thin layer chromatography (TLC) and on-column gas chromatography with mass spectrometry (GC/MS). The fatty acid pattern of total lipids and free fatty acids was analyzed by GC/MS in selected ion monitoring (SIM) mode. Additionally, cholesteryl esters and native fatty acid methyl esters, initially detected as zones in thin layer chromatograms, were enriched by solid phase extraction and quantified by GC/MS. The ratio of free fatty acids to native fatty acid methyl esters could be correlated with the remained body lipids in the polar bears and thus may also serve as a marker for other starving animals or even for humans. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. [Alterations in tears aqueous layer during cytostatics treatment].

    Science.gov (United States)

    Wojciechowska, Katarzyna; Wieckowska-Szakiel, Marzena; Rózalska, Barbara; Jurowski, Piotr

    2013-01-01

    The aim of the study was to evaluate tears secretion, pH and lysozyme activity in tears aqueous layer during chemotherapy in lung, breast and bowel cancer. 36 patients were enrolled to the study. Depending on the type of cancer and type of chemotherapy patients were divided into three groups. Group I (12 patients) diagnosed with non-small-cell lung cancer treated with PE schema (cisplatin, etoposide), Group II (12 patients) with breast cancer treated with FAC schema (fluorouracil, doxorubicin, cyclophosphamide), Group III (12 patients) with bowel cancer treated with FU/LV schema (fluorouracil, leucovorin). In all the patients: Schirmer's I test, pH measurements and lysozyme test were performed. Patients were examined before chemotherapy, after 2nd, 4th, 6th cycle. In group I and II lowering of tears secretion (p tears secretion (p tears film in all groups (p tears aqueous layer causing alterations of tears secretions. PH alterations depending on type of chemotherapy was observed. Lowering of lysozyme activity in tears was observed. All the deteriorations aggravate with duration of chemotherapy. Alterations of tears film parameters during chemotherapy may influence upon eye surface homeostasis and infectious complication. tears aqueous layer, Schirmer's test, lysozyme activity, tears pH.

  1. The Spectrophotometric Sulfo-Phospho-Vanillin Assessment of Total Lipids in Human Meibomian Gland Secretions

    Science.gov (United States)

    McMahon, Anne; Lu, Hua

    2013-01-01

    Human meibomian gland secretions (meibum) are the major lipid component of the human preocular tear film. The predominant lipid classes found in meibum include waxes (WE), cholesteryl esters (CE), and varying amounts of cholesterol (Chl). The classical sulfo-phospho-vanillin assay (SPVA), adapted for a microplate reader, was used to quantitate lipids in meibum. To account for varying reactivities of different lipids in SPVA, a model meibomian lipid mixture (MMx) that approximated the WE/CE/Chl composition of meibum was developed and used to quantitate meibomian lipids. The overall SPV responses of MMx and meibum were found to be close, with similar intermediate and final reaction products for both. Saturated WE that had not been expected to be reactive were found to be SPV-positive. A reaction mechanism for these compounds in SPVA which involves the formation of alkenyl ethers is proposed and discussed. Tested proteins were non-reactive in SPVA. Thus, by comparing the results of gravimetric analyses of meibum samples with the results of a properly calibrated SPVA, it was estimated that the SPV-reactive lipid content of dry meibum in tested samples was about 78 % (w/w). The SPV method can also be adopted for analyzing other types of complex lipids secretions, such as sebum, as well as whole lipid extracts from other lipid-enriched organs and tissues, if proper standards are chosen. PMID:23345137

  2. In vitro skin penetration of clobetasol from lipid nanoparticles: drug extraction and quantitation in different skin layers

    Directory of Open Access Journals (Sweden)

    Luís Antônio Dantas Silva

    2012-12-01

    Full Text Available Clobetasol propionate (CP is a potent topical corticosteroid that causes several cutaneous and systemic side effects. In the present work, CP was encapsulated in nanostructured lipid carriers (NLCs to increase drug retention in the outer skin layers and improve the safety of topical therapy. NLCs were prepared using a microemulsion technique with a mixture of lecithin, taurodeoxycholate, stearic acid, and oleic acid. In vitro penetration studies were performed in a modified Franz-type diffusion cell, and porcine ears were used as a model of human skin. A simple and sensitive liquid chromatographic method was developed and validated for clobetasol determination in different skin layers. NLCs presented uniform size distribution, high zeta potentialand entrapment efficiency values (> 98%. The analytical procedure was validated according to FDA guidelines. Clobetasol recoveries from skin samples were higher than 85%, with no interference of skin components and NLC ingredients. In experiments, after 6 h, a higher drug accumulation in the stratum corneum arising from NLCs compared to aqueous CP solution was observed. Thus, the NLCs demonstrated high potential for targeting CP to the skin and ensuring drug accumulation in the stratum corneum.Proprionato de clobetasol (CP é um potente corticóide tópico, que apresenta vários efeitos adversos cutâneos e sistêmicos. No presente trabalho, CP foi encapsulado em carreadores lipídicos nanoestruturados (NLCs visando aumentar a retenção do fármaco nas camadas superficiais da pele e a segurança da terapia tópica. NLCs foram preparados usando a técnica de diluição de microemulsão com mistura de lecitina, taurodesoxicolato, ácido esteárico e ácido oléico. Estudos de penetração in vitro foram realizados em células de difusão de Franz modificadas usando pele de orelha de porco como modelo de pele humana. Um método simples e sensível de cromatografia líquida foi desenvolvido e validado para

  3. Deposition of lipid, protein, and secretory phospholipase A2 on hydrophilic contact lenses.

    Science.gov (United States)

    Mochizuki, Hiroshi; Yamada, Masakazu; Hatou, Shin; Kawashima, Motoko; Hata, Seiichiro

    2008-01-01

    Recent studies have shown that low tear phospholipid levels are associated with tear film instability in hydrophilic contact lens wearers. The concentration of secretory phospholipase A2 (sPLA2), the enzyme that hydrolyzes phospholipids, in tears is known to exceed the levels found in serum by four orders of magnitude. This study was performed to determine the levels of sPLA2 from the deposition on two different frequent-replacement contact lens materials. Polymacon and etafilcon A contact lenses worn for 2 weeks by 16 experienced contact lens wearers were used for the analysis. Total lipids were determined by the sulfo-phospho-vanillin reaction. Phospholipids in lipid extracts were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Total protein was measured by bicinchoninic acid analysis. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine sPLA2 concentrations. Total lipid deposition was found to be greater in the polymacon group (66.3+/-16.3 microg/lens) than in the etafilcon A group, although phospholipids were not detected in either group. The etafilcon A group had greater deposition of protein (3.7+/-0.7 mg/lens) than the polymacon group had. The etafilcon A group deposited statistically significantly more group IIa sPLA2 (1.1+/-0.3 microg/lens) than the polymacon group (0.07+/-0.04 microg/lens) did (P<0.001). There was a significant difference in the lipid and protein deposition profiles in the two lenses tested. A significant amount of sPLA2 in the deposition on contact lenses may play a role in tear film instability in hydrophilic contact lens wearers.

  4. On the lipid head group hydration of floating surface monolayers bound to self-assembled molecular protein layers

    DEFF Research Database (Denmark)

    Lösche, M.; Erdelen, C.; Rump, E.

    1994-01-01

    kept at low surface pressure before protein adsorption. The introduction of dipole moments at the interface by the admixture of phospholipids or the application of lateral pressure on the lipid monolayer before protein adsorption were found to impose an extension of the spacer moieties. The biotin...

  5. Protein and lipid oxidation affect the viscoelasticity of whey protein layers at the oil-water interface

    NARCIS (Netherlands)

    Berton-Carabin, Claire C.; Schroder, Anja; Rovalino-Cordova, Ana; Schroën, Karin; Sagis, Leonard

    2016-01-01

    Protein and lipid oxidation are prevailing issues that negatively affect the nutritional and sensory quality of food emulsions. It is probable that such oxidative modifications affect the functional properties of proteins, and in particular their ability to form densely packed, interconnected

  6. An evaluation of Retaine™ ophthalmic emulsion in the management of tear film stability and ocular surface staining in patients diagnosed with dry eye

    Directory of Open Access Journals (Sweden)

    Ousler III G

    2015-02-01

    and improves the quality of life of dry eye subjects while reducing the ocular signs of dry eye.Keywords: artificial tears, dry eye syndrome, quality of life, cationic, lipid emulsion, mean breakup area

  7. The surface activity of purified ocular mucin at the air-liquid interface and interactions with meibomian lipids.

    Science.gov (United States)

    Millar, Thomas J; Tragoulias, Sophia T; Anderton, Philip J; Ball, Malcolm S; Miano, Fausto; Dennis, Gary R; Mudgil, Poonam

    2006-01-01

    Ocular mucins are thought to contribute to the stability of the tear film by reducing surface tension. The purpose of this study was to compare the effect of different mucins and hyaluronic acid (HA) alone and mixed with meibomian lipids on the surface pressure at an air-liquid interface. A Langmuir trough and Wilhelmy balance were used to measure and compare the surface activity of bovine submaxillary gland mucin (BSM), purified BSM, purified bovine ocular mucin and HA, and mixtures of these with meibomian lipids, phosphatidylcholine, and phosphatidylglycerol. Their appearance at the surface of an air-buffer interface was examined using epifluorescence microscopy. Purified ocular mucin had no surface activity even at concentrations that were 100 times more than normally occur in tears. By contrast, commercial BSM caused changes to surface pressure that were concentration dependent. The surface pressure-area profiles showed surface activity with maximum surface pressures of 12.3-22.5 mN/m depending on the concentration. Purified BSM showed no surface activity at low concentrations, whereas higher concentrations reached a maximum surface pressure of 25 mN/m. HA showed no surface activity, at low or high concentrations. Epifluorescence showed that the mucins were located at the air-buffer interface and changed the appearance of lipid films. Purified bovine ocular mucin and HA have no surface activity. However, despite having no surface activity in their own right, ocular mucins are likely to be present at the surface of the tear film, where they cause an increase in surface pressure by causing a compression of the lipids (a reorganization of the lipids) and alter the viscoelastic properties at the surface.

  8. Effect of Dietary Marine Microalgae ( Powder on Egg Production, Blood Lipid Profiles, Egg Quality, and Fatty Acid Composition of Egg Yolk in Layers

    Directory of Open Access Journals (Sweden)

    J. H. Park

    2015-03-01

    Full Text Available Two hundred and sixteen Institut de Sélection Animale (ISA brown layers (40 wks of age were studied for 6 wks to examine the effect of microalgae powder (MAP on egg production, egg quality, blood lipid profile, and fatty acid concentration of egg yolk. Dietary treatments were as follows: i CON (basal diet, ii 0.5% MAP (CON+0.5% Schizochytrium powder, and iii 1.0% MAP (CON+1.0% Schizochytrium powder. From 44 to 46 wks, egg production was higher in 1.0% MAP treatment than in control treatment (linear, p = 0.034; however, there was no difference on the egg production from 40 to 43 wks (p>0.05. Serum triglyceride and total cholesterol were significantly reduced in the groups fed with MAP, compared to those in groups fed with control diets (Quadratic, p = 0.034 and p = 0.039, respectively. Inclusion of 0.5% MAP in the diet of layers improved egg yolk color, compared with hens fed with basal diet at 46 wks (quadratic, p = 0.044. Eggshell thickness was linearly increased in MAP-fed treatments at 46th wk (p<0.05. Concentration of yolk docosahexaenoic acid (DHA; C22:6n-3 was increased in treatment groups fed with MAP (linear, p<0.05. The n-6 fatty acids, n-6/n-3 fatty acid, and unsaturated fatty acid/saturated fatty acid were decreased in treatment groups fed with MAP (linear, p<0.05. These results suggest that MAP improved the egg production and egg quality, and may affect serum lipid metabolites in the layers. In addition, MAP increases yolk DHA levels, and deceases n-6/n-3 fatty acid ratio.

  9. Permuting the PGF Signature Motif Blocks both Archaeosortase-Dependent C-Terminal Cleavage and Prenyl Lipid Attachment for the Haloferax volcanii S-Layer Glycoprotein.

    Science.gov (United States)

    Abdul Halim, Mohd Farid; Karch, Kelly R; Zhou, Yitian; Haft, Daniel H; Garcia, Benjamin A; Pohlschroder, Mechthild

    2015-12-28

    For years, the S-layer glycoprotein (SLG), the sole component of many archaeal cell walls, was thought to be anchored to the cell surface by a C-terminal transmembrane segment. Recently, however, we demonstrated that the Haloferax volcanii SLG C terminus is removed by an archaeosortase (ArtA), a novel peptidase. SLG, which was previously shown to be lipid modified, contains a C-terminal tripartite structure, including a highly conserved proline-glycine-phenylalanine (PGF) motif. Here, we demonstrate that ArtA does not process an SLG variant where the PGF motif is replaced with a PFG motif (slg(G796F,F797G)). Furthermore, using radiolabeling, we show that SLG lipid modification requires the PGF motif and is ArtA dependent, lending confirmation to the use of a novel C-terminal lipid-mediated protein-anchoring mechanism by prokaryotes. Similar to the case for the ΔartA strain, the growth, cellular morphology, and cell wall of the slg(G796F,F797G) strain, in which modifications of additional H. volcanii ArtA substrates should not be altered, are adversely affected, demonstrating the importance of these posttranslational SLG modifications. Our data suggest that ArtA is either directly or indirectly involved in a novel proteolysis-coupled, covalent lipid-mediated anchoring mechanism. Given that archaeosortase homologs are encoded by a broad range of prokaryotes, it is likely that this anchoring mechanism is widely conserved. Prokaryotic proteins bound to cell surfaces through intercalation, covalent attachment, or protein-protein interactions play critical roles in essential cellular processes. Unfortunately, the molecular mechanisms that anchor proteins to archaeal cell surfaces remain poorly characterized. Here, using the archaeon H. volcanii as a model system, we report the first in vivo studies of a novel protein-anchoring pathway involving lipid modification of a peptidase-processed C terminus. Our findings not only yield important insights into poorly understood

  10. Effects of Supplementation of Alkaloid and Non Alkaloid from Sauropus androgynus Leaves on Egg Production and Lipid Profil in Layer Chicken

    Directory of Open Access Journals (Sweden)

    U Santoso

    2010-09-01

    Full Text Available The present study was conducted to evaluate effects of supplementation of alkaloid or non alkaloid from Sauropus androgynus leaves on productive performance and the contents of lipid fractions in layer chickens. Forty two layer chickens aged 30 weeks were distributed to seven treatment groups. Each treatment group contained six layer chickens maintained in an individual cage, respectively. The present experiment used completely randomized experimental design. The seven treatment groups were as follows: 1 Control, layer chickens were fed diet without supplementation of alkaloid or non alkaloid extracted from Sauropus androgynus (P0; 2 Layer chickens were fed diet contained 30 mg non alkaloid/kg diet (P1; 3 Layer chickens were fed diet contained 60 mg non alkaloid/kg diet (P2; 4 Layer chickens were fed diet contained 90 mg non alkaloid/kg diet (P3; 5 Layer chickens were fed diet contained 30 mg alkaloid/kg diet (P4; 6 Layer chickens were fed diet contained 60 mg alkaloid/kg diet (P5; 7 Layer chickens were fed diet contained 90 mg alkaloid/kg diet (P6. Layer chickens were fed experimental diet with 2,750 kcal/kg Metabolizable Energy (ME and 16.0% protein. Diet and drinking water were fed ad libitum. Experimental results showed that supplementation of alkaloid or non alkaloid from Sauropus androgynus leaves significantly affected productive performance in layer chickens. It appear that non alkaloid supplementation had no advantage in improving productive performance, whereas supplementation of 30 mg alkaloid/kg diet might have advantages in improving productive performance as indicated by better egg production and lower feed conversion ratio. Treatment had no effect on glucose and triglyceride concentration in serum, but it affected total cholesterol, HDL-cholesterol, LDL+VLDL-cholesterol and atherogenic index in serum. Cholesterol concentration in serum was significantly increased in P4 and P6, whereas HDL-cholesterol concentration was

  11. What Is Dry Eye?

    Medline Plus

    Full Text Available ... vision. The tear film is made of three layers: An oily layer A watery layer A mucus layer Each layer of the tear film serves a purpose. The oily layer is the outside of the tear film. It ...

  12. Dual-layered nanogel-coated hollow lipid/polypeptide conjugate assemblies for potential pH-triggered intracellular drug release.

    Directory of Open Access Journals (Sweden)

    Wen-Hsuan Chiang

    Full Text Available To achieve effective intracellular anticancer drug delivery, the polymeric vesicles supplemented with the pH-responsive outlayered gels as a delivery system of doxorubicin (DOX were developed from self-assembly of the lipid/polypeptide adduct, distearin grafted poly(γ-glutamic acid (poly(γ-GA, followed by sequential deposition of chitosan and poly(γ-GA-co-γ-glutamyl oxysuccinimide-g-monomethoxy poly(ethylene glycol in combination with in situ covalent cross-linking on assembly surfaces. The resultant gel-caged polymeric vesicles (GCPVs showed superior performance in regulating drug release in response to the external pH change. Under typical physiological conditions (pH 7.4 and 37 °C at which the γ-GA/DOX ionic pairings remained mostly undisturbed, the dense outlayered gels of GCPVs significantly reduced the premature leakage of the uncomplexed payload. With the environmental pH being reduced from pH 7.4 to 4.7, the drug liberation was appreciably promoted by the massive disruption of the ionic γ-GA/DOX complexes along with the significant swelling of nanogel layers upon the increased protonation of chitosan chain segments. After being internalized by HeLa cells via endocytosis, GCPVs exhibited cytotoxic effect comparable to free DOX achieved by rapidly releasing the payload in intracellular acidic endosomes and lysosomes. This strongly implies the great promise of such unique GCPVs as an intracellular drug delivery carrier for potential anticancer treatment.

  13. Fontes de lipídios na dieta de poedeiras: desempenho produtivo e qualidade dos ovos Lipids sources on layer hen diet: performance and egg quality

    Directory of Open Access Journals (Sweden)

    D.D. Oliveira

    2010-06-01

    Full Text Available Os efeitos de fontes de lipídios na dieta de poedeiras sobre o desempenho produtivo e a qualidade do ovo foram verificados em dois experimentos. Foram utilizados quatro tratamentos, definidos de acordo com a fonte lipídica adicionada nas rações: óleo de soja, óleo de girassol, óleo de linhaça e ração controle (sem adição de óleo. Os experimentos foram realizados com poedeiras de 20 e 54 semanas de idade, respectivamente, com duração de oito semanas. Avaliaram-se os parâmetros produtivos - consumo de ração, conversão alimentar, produção e peso dos ovos - e de qualidade do ovo - porcentagens de gema, albúmen e casca, sólidos da gema, unidades Haugh, pH do albúmen, e cor da gema. Somente o peso do ovo de poedeiras jovens foi afetado pela inclusão de óleos vegetais na ração. Esses ovos apresentaram maior peso e maior porcentagem de gema que os produzidos pelas poedeiras jovens alimentadas com ração-controle. Concluiu-se que a utilização de diferentes fontes de lipídios na ração de poedeiras não altera o desempenho produtivo e a qualidade interna dos ovos, com exceção do peso do ovo de poedeiras novas, que aumenta com a utilização de óleos vegetais.The effects of different sources of fat in the diet of layer hens on performance and egg quality were recorded in two experiments. Four treatments were defined by the lipid source added to the diets: soybean oil, sunflower oil, linseed oil and control diet (without oil added. The experiments were carried out with layers from 20 to 54 weeks of age, respectively, for eight weeks. Production parameters (feed intake, feed conversion, egg production, and egg weight and quality of eggs (percentages of yolk, albumen, and shell; total solids of yolk; Haugh units; pH of albumen; and yolk color were evaluated. Among the parameters of production and quality of the eggs, only the weight of eggs and percentage of yolk of young hens were affected by the inclusion of vegetable

  14. What Is Dry Eye?

    Medline Plus

    Full Text Available ... of tears or tear film . How do tears work? When you blink, a film of tears spreads ... eyes don’t make enough tears or something affects one or more layers of the tear film. ...

  15. A novel technique of contrast-enhanced optical coherence tomography imaging in evaluation of clearance of lipids in human tears.

    Science.gov (United States)

    Napoli, Pietro Emanuele; Coronella, Franco; Satta, Giovanni Maria; Fossarello, Maurizio

    2014-01-01

    The aim of this work was to gather preliminary data in different conditions of healthy eyes, aqueous tear deficient dry eyes, obstructive meibomian gland disease (MGD) and non-obvious obstructive MGD (NOMGD) individuals, using a new, contrast-enhanced optical coherence tomography (OCT) imaging method to evaluate the clearance of lipids in human tears. Eighty-two adult patients presenting with complaints of ocular irritation were studied for abnormalities of the ocular surface and classified as healthy (n = 21), aqueous tear deficient dry eyes (n = 20), obstructive MGD (n = 15) and NOMGD (n = 26) individuals. A lipid-based tracer, containing an oil-in-water emulsion, was used to obtain an enhanced OCT imaging of the lower tear meniscus. After instillation, a dramatic initial increase of reflectivity of the lower tear meniscus was detected by OCT, followed by a decay back to baseline values over time. Based on this finding, the clearance of lipids was measured in real-time by Fourier-domain anterior segment OCT. The differences in the clearance of lipids among the four groups as well as the correlations between symptom questionnaire score, standardized visual scale test, fluorescein break-up time, ocular surface fluorescein staining score, Schirmer I test scores were found to be statistically significant. The individual areas under the curve of the clearance of lipids calculated by the receiver operating characteristic curve technique ranged from 0.66 to 0.98, suggesting reliable sensitivity and specificity of lipid-enhanced OCT imaging. This new technique of contrast-enhanced OCT imaging of the tear film following lipid-based tracer instillation provides a measure of the clearance of lipids. The quantitative values found are in agreement with other methods of evaluation of the lacrimal system. An improvement of the clinician's ability in the diagnosis and understanding of abnormalities of the ocular surface may be achieved by this simple approach.

  16. Acyl-Lipid Metabolism

    Science.gov (United States)

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2013-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:23505340

  17. Lipid somersaults

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Menon, Anant K.

    2016-01-01

    Membrane lipids diffuse rapidly in the plane of the membrane but their ability to flip spontaneously across a membrane bilayer is hampered by a significant energy barrier. Thus spontaneous flip-flop of polar lipids across membranes is very slow, even though it must occur rapidly to support diverse...... aspects of cellular life. Here we discuss the mechanisms by which rapid flip-flop occurs, and what role lipid flipping plays in membrane homeostasis and cell growth. We focus on conceptual aspects, highlighting mechanistic insights from biochemical and in silico experiments, and the recent, ground......-breaking identification of a number of lipid scramblases....

  18. Comparisons of protein, lipid, phenolics, γ-oryzanol, vitamin E, and mineral contents in bran layer of sodium azide-induced red rice mutants.

    Science.gov (United States)

    Jeng, Toong Long; Ho, Pei Tzu; Shih, Yi Ju; Lai, Chia Chi; Wu, Min Tze; Sung, Jih Min

    2011-06-01

    The bran part of red rice grain is concentrated with many phytochemicals, including proanthocyanidins, oryzanol and vitamin E, that exert beneficial effects on human health, but it contains low levels of essential minerals such as Fe and Zn. In the present study, the protein, lipid, phytochemicals and mineral contents in bran samples were compared among red rice SA-586 and its NaN₃-induced mutants. The plant heights of NaN₃-induced mutants were decreased. The contents of protein, lipid, total phenolics, total flavonoids, total anthocyanins, total proanthocyanidins, total γ-oryzanol, total tocopherols and total tocotrienols also varied among the tested mutants. The brans of mutants M-18, M-56 and M-50 contained more proanthocyanidins, γ-oryzanol, vitamin E than that of SA-586, respectively. M-54 accumulated more Fe content (588.7 mg kg⁻¹ bran dry weight) than SA-586 (100.1 mg kg⁻¹ bran dry weight). The brans of M-18, M-50 and M-56 are good sources of proanthocyanidins, vitamin E and γ-oryzanol, respectively, while the bran of M-54 is rich in Fe. Thus these mutants could be used to produce high-value phytochemicals or Fe byproducts from bran during rice grain milling or as genetic resources for rice improvement programs. Copyright © 2011 Society of Chemical Industry.

  19. Lipid shell-enveloped polymeric nanoparticles with high integrity of lipid shells improve mucus penetration and interaction with cystic fibrosis-related bacterial biofilms

    DEFF Research Database (Denmark)

    Wan, Feng; Nylander, Tommy; Klodzinska, Sylvia Natalie

    2018-01-01

    , we describe facile methods to prepare Lipid@NPs with high integrity of lipid shells and demonstrate the potential of Lipid@NPs in effective mucus penetration and interaction with cystic fibrosis-related bacterial biofilms. Lipid shell-enveloped polystyrene NPs with high integrity of lipid shells (c...... mediated layer-by layer approach. Our results suggest that the integrity of the lipid envelopes is crucial for enabling the diffusion of Lipid@PSNPs into the mucus layer and promoting the interaction of Lipid@PSNPs with a bacterial biofilm....

  20. Inclusion of the helper lipid dioleoyl-phosphatidylethanolamine in solid lipid nanoparticles inhibits their transfection efficiency

    NARCIS (Netherlands)

    de Jesus, Marcelo B.; Radaic, Allan; Hinrichs, Wouter L J; Ferreira, Carmen V; de Paula, Eneida; Hoekstra, Dirk; Zuhorn, Inge S

    Solid lipid nanoparticles (SLNs) are a promising system for the delivery of lipophilic and hydrophilic drugs. They consist of a solid lipid core that is stabilized by a layer of surfactants. By the incorporation of cationic lipids in the formulation, positively charged SLNs can be generated, that

  1. Dermal extracellular lipid in birds.

    Science.gov (United States)

    Stromberg, M W; Hinsman, E J; Hullinger, R L

    1990-01-01

    A light and electron microscopic study of the skin of domestic chickens, seagulls, and antarctic penguins revealed abundant extracellular dermal lipid and intracellular epidermal lipid. Dermal lipid appeared ultrastructurally as extracellular droplets varying from less than 1 micron to more than 25 microns in diameter. The droplets were often irregularly contoured, sometimes round, and of relatively low electron density. Processes of fibrocytes were often seen in contact with extracellular lipid droplets. Sometimes a portion of such a droplet was missing, and this missing part appeared to have been "digested away" by the cell process. In places where cells or cell processes are in contact with fact droplets, there are sometimes extracellular membranous whorls or fragments which have been associated with the presence of fatty acids. Occasionally (in the comb) free fat particles were seen in intimate contact with extravasated erythrocytes. Fat droplets were seen in the lumen of small dermal blood and lymph vessels. We suggest that the dermal extracellular lipid originates in the adipocyte layer and following hydrolysis the free fatty acids diffuse into the epidermis. Here they become the raw material for forming the abundant neutral lipid contained in many of the epidermal cells of both birds and dolphins. The heretofore unreported presence and apparently normal utilization of abundant extracellular lipid in birds, as well as the presence of relatively large droplets of neutral lipid in dermal vessels, pose questions which require a thorough reappraisal of present concepts of the ways in which fat is distributed and utilized in the body.

  2. Lipid Nanotechnology

    Directory of Open Access Journals (Sweden)

    Gijsje Koenderink

    2013-02-01

    Full Text Available Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices and machines derived from engineering, physics, materials science, chemistry and biology. These devices have found applications in biomedical sciences, such as targeted drug delivery, bio-imaging, sensing and diagnosis of pathologies at early stages. In these applications, nano-devices typically interface with the plasma membrane of cells. On the other hand, naturally occurring nanostructures in biology have been a source of inspiration for new nanotechnological designs and hybrid nanostructures made of biological and non-biological, organic and inorganic building blocks. Lipids, with their amphiphilicity, diversity of head and tail chemistry, and antifouling properties that block nonspecific binding to lipid-coated surfaces, provide a powerful toolbox for nanotechnology. This review discusses the progress in the emerging field of lipid nanotechnology.

  3. Lipids in airway secretions

    International Nuclear Information System (INIS)

    Bhaskar, K.R.; DeFeudis O'Sullivan, D.; Opaskar-Hincman, H.; Reid, L.M.

    1987-01-01

    Lipids form a significant portion of airway mucus yet they have not received the same attention that epithelial glycoproteins have. We have analysed, by thin layer chromatography, lipids present in airway mucus under 'normal' and hypersecretory (pathological) conditions.The 'normals' included (1) bronchial lavage obtained from healthy human volunteers and from dogs and (2) secretions produced ''in vitro'' by human (bronchial) and canine (tracheal) explants. Hypersecretory mucus samples included (1) lavage from dogs made bronchitic by exposure to SO 2 , (2) bronchial aspirates from acute and chronic tracheostomy patients, (3) sputum from patients with cystic fibrosis and chronic bronchitis and (4) postmortem secretions from patients who died from sudden infant death syndrome (SIDS) or from status asthmaticus. Cholesterol was found to be the predominant lipid in 'normal' mucus with lesser amounts of phospholipids. No glycolipids were detected. In the hypersecretory mucus, in addition to neutral and phospholipids, glycolipids were present in appreciable amounts, often the predominant species, suggesting that these may be useful as markers of disease. Radioactive precursors 14 C acetate and 14 C palmitate were incorporated into lipids secreted ''in vitro'' by canine tracheal explants indicating that they are synthesised by the airway. (author)

  4. Sebum/Meibum Surface Film Interactions and Phase Transitional Differences.

    Science.gov (United States)

    Mudgil, Poonam; Borchman, Douglas; Gerlach, Dylan; Yappert, Marta C

    2016-05-01

    Sebum may contribute to the composition of the tear film lipid layer naturally or as a contaminant artifact from collection. The aims of this study were to determine: if sebum changes the rheology of meibum surface films; if the resonance near 5.2 ppm in the 1H-NMR spectra of sebum is due to squalene (SQ); and if sebum or SQ, a major component of sebum, interacts with human meibum. Human meibum was collected from the lid margin with a platinum spatula. Human sebum was collected using lipid absorbent tape. Langmuir trough technology was used to measure the rheology of surface films. Infrared spectroscopy was used to measure lipid conformation and phase transitions. We used 1H-NMR to measure composition and confirm the primary structure of SQ. The NMR resonance near 5.2 ppm in the spectra of human sebum was from SQ which composed 28 mole percent of sebum. Both sebum and SQ lowered the lipid order of meibum. Sebum expanded meibum films at lower concentrations and condensed meibum films at higher concentrations. Sebum caused meibum to be more stable at higher pressures (greater maximum surface pressure). Physiological levels of sebum would be expected to expand or fluidize meibum making it spread better and be more surface active (qualities beneficial for tear film stability). Sebum would also be expected to stabilize the tear film lipid layer, which may allow it to withstand the high shear pressure of a blink.

  5. Sebum/Meibum Surface Film Interactions and Phase Transitional Differences

    Science.gov (United States)

    Mudgil, Poonam; Borchman, Douglas; Gerlach, Dylan; Yappert, Marta C.

    2016-01-01

    Purpose Sebum may contribute to the composition of the tear film lipid layer naturally or as a contaminant artifact from collection. The aims of this study were to determine: if sebum changes the rheology of meibum surface films; if the resonance near 5.2 ppm in the 1H-NMR spectra of sebum is due to squalene (SQ); and if sebum or SQ, a major component of sebum, interacts with human meibum. Methods Human meibum was collected from the lid margin with a platinum spatula. Human sebum was collected using lipid absorbent tape. Langmuir trough technology was used to measure the rheology of surface films. Infrared spectroscopy was used to measure lipid conformation and phase transitions. We used 1H-NMR to measure composition and confirm the primary structure of SQ. Results The NMR resonance near 5.2 ppm in the spectra of human sebum was from SQ which composed 28 mole percent of sebum. Both sebum and SQ lowered the lipid order of meibum. Sebum expanded meibum films at lower concentrations and condensed meibum films at higher concentrations. Sebum caused meibum to be more stable at higher pressures (greater maximum surface pressure). Conclusions Physiological levels of sebum would be expected to expand or fluidize meibum making it spread better and be more surface active (qualities beneficial for tear film stability). Sebum would also be expected to stabilize the tear film lipid layer, which may allow it to withstand the high shear pressure of a blink. PMID:27145473

  6. Layer-by-layer cell membrane assembly

    Science.gov (United States)

    Matosevic, Sandro; Paegel, Brian M.

    2013-11-01

    Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

  7. Lipid Panel

    Science.gov (United States)

    ... A routine cardiac risk assessment typically includes a fasting lipid panel. Beyond that, research continues into the usefulness of other non-traditional markers of cardiac risk, such as Lp-PLA 2 . A health practitioner may choose to evaluate one or more ...

  8. LipidPedia: a comprehensive lipid knowledgebase.

    Science.gov (United States)

    Kuo, Tien-Chueh; Tseng, Yufeng Jane

    2018-04-10

    Lipids are divided into fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, sterols, prenol lipids and polyketides. Fatty acyls and glycerolipids are commonly used as energy storage, whereas glycerophospholipids, sphingolipids, sterols and saccharolipids are common used as components of cell membranes. Lipids in fatty acyls, glycerophospholipids, sphingolipids and sterols classes play important roles in signaling. Although more than 36 million lipids can be identified or computationally generated, no single lipid database provides comprehensive information on lipids. Furthermore, the complex systematic or common names of lipids make the discovery of related information challenging. Here, we present LipidPedia, a comprehensive lipid knowledgebase. The content of this database is derived from integrating annotation data with full-text mining of 3,923 lipids and more than 400,000 annotations of associated diseases, pathways, functions, and locations that are essential for interpreting lipid functions and mechanisms from over 1,400,000 scientific publications. Each lipid in LipidPedia also has its own entry containing a text summary curated from the most frequently cited diseases, pathways, genes, locations, functions, lipids and experimental models in the biomedical literature. LipidPedia aims to provide an overall synopsis of lipids to summarize lipid annotations and provide a detailed listing of references for understanding complex lipid functions and mechanisms. LipidPedia is available at http://lipidpedia.cmdm.tw. yjtseng@csie.ntu.edu.tw. Supplementary data are available at Bioinformatics online.

  9. Tear Film Functions and Intraocular Pressure Changes in Pregnancy.

    African Journals Online (AJOL)

    AJRH Managing Editor

    Skare TL, Gehlen ML, Silveira DMG, Uema MMDS. Pregnancy and lacrimal dysfunction. Rev. Bras. Ginecol. Obstet. 2012;34(4):170-4. 7. Ding C, Lu M, Huang J. Changes of the ocular surface and aquaporins in the lacrimal glands of rabbits. During pregnancy. Mol Vis. 2011;17:2847-55. 8. Goldich Y, Cooper M, Barkana Y, ...

  10. Efficacy and Safety of Carbomer-Based Lipid-Containing Artificial Tear Formulations in Patients With Dry Eye Syndrome.

    Science.gov (United States)

    Chung, So-Hyang; Lim, Sung A; Tchach, Hungwon

    2016-02-01

    To evaluate the efficacy and safety profile of carbomer-based lipid-containing artificial tear formulations (CBLAT) in patients with dry eye syndrome. A multicenter parallel-group study was conducted in 412 patients with dry eye syndrome. Of these patients, 221 switched from using artificial tears to CBLAT (switching group) and 191 added CBLAT to their current treatment (add-on group). Ocular symptom scores, ocular staining grades, tear film breakup time (tBUT), Schirmer I test value, and Korean dry eye level (as defined by the Korean Corneal Disease Study Group guidelines) were evaluated at baseline and after 4 weeks of treatment. After 4 weeks of treatment, ocular surface staining grade, tBUT, Schirmer I value, ocular irritation symptom scores, and the positive rate of visual symptom improved significantly in both groups. Mean reductions in ocular surface staining grades (-0.8 ± 0.9) and ocular irritation symptom scores (-0.8 ± 0.8) in the add-on group were significantly higher than those (-0.5 ± 0.8 and -0.6 ± 0.8) in the switching group (P dry eye level was 30.1% in the switching group and 51.6% in the add-on group. More patients in the add-on group had decreased dry eye levels than those in the switching group (P dry eye syndrome.

  11. Extraction and classification of lipids from seeds of persea ...

    African Journals Online (AJOL)

    Seed lipids of Persea americana and Chrysophyllum albidum were studied. Lipids were extracted with chloroform-methanol, analysed with silicic column chromatography and thin layer chromatography. The total lipid content of Persea americana was 10.8% while that of Chrysophyllum albidum was 7.7%. Fractionation of ...

  12. Polar lipid composition of mammalian hair.

    Science.gov (United States)

    Wix, M A; Wertz, P W; Downing, D T

    1987-01-01

    The types and amounts of polar lipids from the hair of monkey (Macacca fascicularis), dog (Canis familiaris), pig (Sus scrofa) and porcupine (Erethizon dorsatum) have been determined by quantitative thin-layer chromatography. The polar lipid content of the hair samples ranged from 0.6 to 1.6 wt%. Lipid compositions included ceramides (57-63% of the polar lipid by weight), glycosphingolipids (7-9%) and cholesteryl sulfate (22-29%). Several minor components (4-7%) remain unidentified. The results suggest that cholesteryl sulfate may be an important determinant of the cohesiveness of hair.

  13. Identification of fatty acids and fatty acid amides in human meibomian gland secretions.

    Science.gov (United States)

    Nichols, Kelly K; Ham, Bryan M; Nichols, Jason J; Ziegler, Corrie; Green-Church, Kari B

    2007-01-01

    The complex superficial lipid layer of the tear film functions to prevent evaporation and maintain tear stability. Although classes of lipids found in the tear film have been reported, individual lipid species are currently being studied with more sophisticated. The purpose of this work was to show the identification of fatty acids and the fatty acid amides in human meibomian gland secretions by using electrospray mass spectrometry. methods. Human meibomian gland secretions (meibum) were analyzed by electrospray quadrupole time-of-flight mass spectrometry (positive- and negative-ion mode). Accurate mass determination and collision-induced dissociation of meibum, and lipid standards were used to identify lipid species. Mass analysis of meibum in an acidic chloroform-methanol solution in positive-ion mode revealed a mass peak of m/z 282.3, which was identified as the protonated molecule of oleamide [C(18)H(35)NO+H](+). The high-resolution mass analysis of the m/z 282.2788 peak (oleamide) demonstrated a mass accuracy of 3.2 parts per million (ppm). Collision-induced dissociation of this species from meibum, compared with an oleamide standard, confirmed its identification. Myristic, palmitic, stearic, and oleic free fatty acids were identified in a similar manner, as were the other fatty acid amides (myristamide, palmitamide, stearamide, and erucamide). The findings indicate that oleamide (cis-9-octadecenamide), an endogenous fatty acid primary amide, is a predominant component of meibum when examined by electrospray mass spectrometry. The novel finding of oleamide and other members of the fatty acid amide family in the tear film could lead to additional insights into the role of fatty acid amide activity in human biological systems and may indicate a new function for this lipid class of molecules in ocular surface signaling and/or in the maintenance of the complex tear film.

  14. Interaction of nanoparticles with lipid layers

    Science.gov (United States)

    Park, Jonghyun; Lu, Wei

    2009-08-01

    Poly (amidoamine) dendrimer nanoparticles are used extensively in diverse biological and medical applications. Examples include gene and drug delivery, where nanoparticles disrupt cell membranes to allow the transport of material into cells. The size and surface chemistry of these particles have a strong effect on their interaction with membranes. This paper proposes a three-dimensional phase-field model to investigate how the interaction drives deformation and morphological evolution of the membrane. Attention is focused on the hole-formation process in the membrane. The simulations have demonstrated that a larger amine-terminated generation 7 dendrimer, which has positive charges, causes the formation of a hole in the membrane. The displaced membrane molecules enclose the particle and form a dendrimer-filled membrane vesicle. The effect is significantly reduced for a smaller dendrimer. An acetamide-terminated dendrimer, which has a neutral charge at the surface, does not cause hole formation. These results agree with experimental observations from atomic force microscopy. The study will provide insight into the design of appropriate nanoparticle surface properties for medical applications.

  15. Lipids in citrus sinensis seeds

    International Nuclear Information System (INIS)

    Hamid, S.; Liaquat, L.; Khalid, B.; Khan, J.I.

    2003-01-01

    The seed oil of citrus sinensis when subjected to different physicochemical tests showed moisture 13.2%, ash 7.5%, ester value 1.29%, free fatty acid 0.4%. iodine value 65.0% and protein value 6.0%. According to lipid analysis. the oil was classified into hydrocarbons. wax esters, sterol esters, triglycerides. free fatty acids, 1,3 and 1,2 diglycerides, alcohols, sterols, monoglycerides, phosphatidylethanolamines, phosphatidylcholines and lysophosphatidylethanolamines. The fatty acid (C/sub 12.0/ - C/sub 21.0/) composition of all lipid classes was determined with the help of thin layer and gas liquid chromatography. (author)

  16. Exogenous and endogenous lipids of human hair.

    Science.gov (United States)

    Coderch, L; Oliver, M A; Martínez, V; Manich, A M; Rubio, L; Martí, M

    2017-11-01

    The aim of this study was to characterize the external and internal lipids of Caucasian hair and their influence in different hair properties such as moisture content, hydrophobic character, and mechanical properties. Lipid extraction and their analysis by thin layer chromatography with flame ionization detector were carried out. Lipid rearrangement and water sorption and desorption evaluation of these fibers with and without lipids will also be determined using different techniques such as differential scanning calorimetry, thermogravimetric analysis and dynamic vapor sorption, mainly to evaluate permeation changes of these hair fibers possibly related to the fluidity of the lipids extracted. Caucasian fibers were found to be well hydrated, and moisture diminution was observed mainly for the external lipid extracted fibers. Unexpectedly, the lipid extraction promoted an increase in the break tenacity of the Caucasian fibers. The hydrophobic character of the fiber surfaces indicates the marked hydrophobicity of all fibers. Delipidization promotes only a slight diminution of their hydrophobic properties. Water uptake and desorption studies indicate an important water regain for Caucasian fibers. The external extracted hair fibers presented a diminution of maximum water regain, which surprisingly increases with the following internal lipid extraction. This can be due to a higher water desorption found only for external extracted fibers. The relationship between fluidity of lipids extracted and hair fiber water diffusion were established. Extraction of internal lipids of Caucasian fibers, which have a higher unsaturated lipid content than external lipids of the same hair fiber, leads to a lower water permeability of the fiber. On the capillar formulations should be considered the importance of lipid fluidity to modify the permeability of the fiber. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Spontaneous charged lipid transfer between lipid vesicles.

    Science.gov (United States)

    Richens, Joanna L; Tyler, Arwen I I; Barriga, Hanna M G; Bramble, Jonathan P; Law, Robert V; Brooks, Nicholas J; Seddon, John M; Ces, Oscar; O'Shea, Paul

    2017-10-03

    An assay to study the spontaneous charged lipid transfer between lipid vesicles is described. A donor/acceptor vesicle system is employed, where neutrally charged acceptor vesicles are fluorescently labelled with the electrostatic membrane probe Fluoresceinphosphatidylethanolamine (FPE). Upon addition of charged donor vesicles, transfer of negatively charged lipid occurs, resulting in a fluorescently detectable change in the membrane potential of the acceptor vesicles. Using this approach we have studied the transfer properties of a range of lipids, varying both the headgroup and the chain length. At the low vesicle concentrations chosen, the transfer follows a first-order process where lipid monomers are transferred presumably through the aqueous solution phase from donor to acceptor vesicle. The rate of transfer decreases with increasing chain length which is consistent with energy models previously reported for lipid monomer vesicle interactions. Our assay improves on existing methods allowing the study of a range of unmodified lipids, continuous monitoring of transfer and simplified experimental procedures.

  18. Adsorption of human tear lipocalin to human meibomian lipid films.

    Science.gov (United States)

    Millar, Thomas J; Mudgil, Poonam; Butovich, Igor A; Palaniappan, Chendur K

    2009-01-01

    Tear lipocalin (Tlc) is a major lipid binding protein in tears and is thought to have an important role in stabilizing the Meibomian lipid layer by transferring lipids to it from the aqueous layer or ocular surface, or by adsorbing to it directly. These possible roles have been investigated in vitro using human Tlc. Tlc was purified from human tears by size exclusion chromatography followed by ion exchange chromatography. Three additional samples of the Tlc were prepared by lipidation, delipidation, and relipidation. The lipids extracted from the purified Tlc were analyzed by HPLC-MS followed by fragmentation. Adsorption of these different forms of Tlc to a human Meibomian lipid film spread on the surface of an artificial tear buffer in a Langmuir trough were observed by recording changes in the pressure with time (Pi-T profile) and monitoring the appearance of the film microscopically. These results were compared with similar experiments using a bovine Meibomian lipid film. The results indicated that Tlc binds slowly to a human Meibomian lipid film compared with lysozyme or lactoferrin, even at 37 degrees C. The adsorption of Tlc to a human Meibomian lipid film was very different from its adsorption to a bovine Meibomian lipid film, indicating the nature of the lipids in the film is critical to the adsorption process. Similarly, the different forms of Tlc had quite distinct adsorption patterns, as indicated both by changes in Pi-T profiles and the microscopic appearance of the films. It was concluded that human Tlc was capable of adsorbing to and penetrating into a Meibomian lipid layer, but this process is very complex and depends on both the types of lipids bound to Tlc and the lipid complement comprising the Meibomian lipid film.

  19. Adsorption of Human Tear Lipocalin to Human Meibomian Lipid Films

    Science.gov (United States)

    Millar, Thomas J.; Mudgil, Poonam; Butovich, Igor A.; Palaniappan, Chendur K.

    2009-01-01

    Purpose Tear lipocalin (Tlc) is a major lipid binding protein in tears and is thought to have an important role in stabilizing the Meibomian lipid layer by transferring lipids to it from the aqueous layer or ocular surface, or by adsorbing to it directly. These possible roles have been investigated in vitro using human Tlc. Methods Tlc was purified from human tears by size exclusion chromatography followed by ion exchange chromatography. Three additional samples of the Tlc were prepared by lipidation, delipidation, and relipidation. The lipids extracted from the purified Tlc were analyzed by HPLC-MS followed by fragmentation. Adsorption of these different forms of Tlc to a human Meibomian lipid film spread on the surface of an artificial tear buffer in a Langmuir trough were observed by recording changes in the pressure with time (∏-T profile) and monitoring the appearance of the film microscopically. These results were compared with similar experiments using a bovine Meibomian lipid film. Results The results indicated that Tlc binds slowly to a human Meibomian lipid film compared with lysozyme or lactoferrin, even at 37°C. The adsorption of Tlc to a human Meibomian lipid film was very different from its adsorption to a bovine Meibomian lipid film, indicating the nature of the lipids in the film is critical to the adsorption process. Similarly, the different forms of Tlc had quite distinct adsorption patterns, as indicated both by changes in ∏-T profiles and the microscopic appearance of the films. Conclusions It was concluded that human Tlc was capable of adsorbing to and penetrating into a Meibomian lipid layer, but this process is very complex and depends on both the types of lipids bound to Tlc and the lipid complement comprising the Meibomian lipid film. PMID:18757516

  20. Computer Simulations of Lipid Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xavier F. Fernandez-Luengo

    2017-12-01

    Full Text Available Lipid nanoparticles (LNP are promising soft matter nanomaterials for drug delivery applications. In spite of their interest, little is known about the supramolecular organization of the components of these self-assembled nanoparticles. Here, we present a molecular dynamics simulation study, employing the Martini coarse-grain forcefield, of self-assembled LNPs made by tripalmitin lipid in water. We also study the adsorption of Tween 20 surfactant as a protective layer on top of the LNP. We show that, at 310 K (the temperature of interest in biological applications, the structure of the lipid nanoparticles is similar to that of a liquid droplet, in which the lipids show no nanostructuration and have high mobility. We show that, for large enough nanoparticles, the hydrophilic headgroups develop an interior surface in the NP core that stores liquid water. The surfactant is shown to organize in an inhomogeneous way at the LNP surface, with patches with high surfactant concentrations and surface patches not covered by surfactant.

  1. Membrane Lipid Oscillation: An Emerging System of Molecular Dynamics in the Plant Membrane.

    Science.gov (United States)

    Nakamura, Yuki

    2018-03-01

    Biological rhythm represents a major biological process of living organisms. However, rhythmic oscillation of membrane lipid content is poorly described in plants. The development of lipidomic technology has led to the illustration of precise molecular profiles of membrane lipids under various growth conditions. Compared with conventional lipid signaling, which produces unpredictable lipid changes in response to ever-changing environmental conditions, lipid oscillation generates a fairly predictable lipid profile, adding a new layer of biological function to the membrane system and possible cross-talk with the other chronobiological processes. This mini review covers recent studies elucidating membrane lipid oscillation in plants.

  2. Comparison of pinniped and cetacean prey tissue lipids with lipids of their elasmobranch predator.

    Science.gov (United States)

    Davidson, Bruce; Cliff, Geremy

    2014-01-01

    The great white shark is known to include pinnipeds and cetaceans in its diet. Both groups of marine mammals deposit thick blubber layers around their bodies. Elasmobranchs do not produce adipose tissue, but rather store lipid in their livers, thus a great white predating on a marine mammal will deposit the lipids in its liver until required. Samples from great white liver and muscle, Cape fur seal, Indian Ocean bottlenose dolphin and common dolphin liver, muscle and blubber were analyzed for their lipid and fatty acid profiles. The great white liver and marine mammal blubber samples showed a considerable degree of homogeneity, but there were significant differences when comparing between the muscle samples. Blubber from all three marine mammal species was calculated to provide greater than 95% of lipid intake for the great white shark from the tissues analyzed. Sampling of prey blubber may give a good indication of the lipids provided to the shark predator.

  3. Lipid exchange by ultracentrifugation

    DEFF Research Database (Denmark)

    Drachmann, Nikolaj Düring; Olesen, Claus

    2014-01-01

    , and the complex interplay between the lipids and the P-type ATPases are still not well understood. We here describe a robust method to exchange the majority of the lipids surrounding the ATPase after solubilisation and/or purification with a target lipid of interest. The method is based on an ultracentrifugation...... step, where the protein sample is spun through a dense buffer containing large excess of the target lipid, which results in an approximately 80-85 % lipid exchange. The method is a very gently technique that maintains protein folding during the process, hence allowing further characterization...

  4. Lipid Structure in Triolein Lipid Droplets

    DEFF Research Database (Denmark)

    Chaban, Vitaly V; Khandelia, Himanshu

    2014-01-01

    of a mass of hydrophobic lipid esters coved by phospholipid monolayer. The small size and unique architecture of LDs makes it complicated to study LD structure by modern experimental methods. We discuss coarse-grained molecular dynamics (MD) simulations of LD formation in systems containing 1-palmitoyl-2...... to coarse-grained simulations, the presence of PE lipids at the interface has a little impact on distribution of components and on the overall LD structure. (4) The thickness of the lipid monolayer at the surface of the droplet is similar to the thickness of one leaflet of a bilayer. Computer simulations......Lipid droplets (LDs) are primary repositories of esterified fatty acids and sterols in animal cells. These organelles originate on the lumenal or cytoplasmic side of endoplasmic reticulum (ER) membrane and are released to the cytosol. In contrast to other intracellular organelles, LDs are composed...

  5. Membrane-spanning lipids for an uncompromised monitoring of membrane fusion and intermembrane lipid transfer

    Science.gov (United States)

    Schwarzmann, Günter; Breiden, Bernadette; Sandhoff, Konrad

    2015-01-01

    A Förster resonance energy transfer-based fusion and transfer assay was developed to study, in model membranes, protein-mediated membrane fusion and intermembrane lipid transfer of fluorescent sphingolipid analogs. For this assay, it became necessary to apply labeled reporter molecules that are resistant to spontaneous as well as protein-mediated intermembrane transfer. The novelty of this assay is the use of nonextractable fluorescent membrane-spanning bipolar lipids. Starting from the tetraether lipid caldarchaeol, we synthesized fluorescent analogs with fluorophores at both polar ends. In addition, we synthesized radioactive glycosylated caldarchaeols. These labeled lipids were shown to stretch through bilayer membranes rather than to loop within a single lipid layer of liposomes. More important, the membrane-spanning lipids (MSLs) in contrast to phosphoglycerides proved to be nonextractable by proteins. We could show that the GM2 activator protein (GM2AP) is promiscuous with respect to glycero- and sphingolipid transfer. Saposin (Sap) B also transferred sphingolipids albeit with kinetics different from GM2AP. In addition, we could unambiguously show that the recombinant activator protein Sap C x His6 induced membrane fusion rather than intermembrane lipid transfer. These findings showed that these novel MSLs, in contrast with fluorescent phosphoglycerolipids, are well suited for an uncompromised monitoring of membrane fusion and intermembrane lipid transfer. PMID:26269359

  6. Membrane-spanning lipids for an uncompromised monitoring of membrane fusion and intermembrane lipid transfer.

    Science.gov (United States)

    Schwarzmann, Günter; Breiden, Bernadette; Sandhoff, Konrad

    2015-10-01

    A Förster resonance energy transfer-based fusion and transfer assay was developed to study, in model membranes, protein-mediated membrane fusion and intermembrane lipid transfer of fluorescent sphingolipid analogs. For this assay, it became necessary to apply labeled reporter molecules that are resistant to spontaneous as well as protein-mediated intermembrane transfer. The novelty of this assay is the use of nonextractable fluorescent membrane-spanning bipolar lipids. Starting from the tetraether lipid caldarchaeol, we synthesized fluorescent analogs with fluorophores at both polar ends. In addition, we synthesized radioactive glycosylated caldarchaeols. These labeled lipids were shown to stretch through bilayer membranes rather than to loop within a single lipid layer of liposomes. More important, the membrane-spanning lipids (MSLs) in contrast to phosphoglycerides proved to be nonextractable by proteins. We could show that the GM2 activator protein (GM2AP) is promiscuous with respect to glycero- and sphingolipid transfer. Saposin (Sap) B also transferred sphingolipids albeit with kinetics different from GM2AP. In addition, we could unambiguously show that the recombinant activator protein Sap C x His6 induced membrane fusion rather than intermembrane lipid transfer. These findings showed that these novel MSLs, in contrast with fluorescent phosphoglycerolipids, are well suited for an uncompromised monitoring of membrane fusion and intermembrane lipid transfer. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

  7. Hydration dynamics of a lipid membrane: Hydrogen bond networks and lipid-lipid associations

    Science.gov (United States)

    Srivastava, Abhinav; Debnath, Ananya

    2018-03-01

    Dynamics of hydration layers of a dimyristoylphosphatidylcholine (DMPC) bilayer are investigated using an all atom molecular dynamics simulation. Based upon the geometric criteria, continuously residing interface water molecules which form hydrogen bonds solely among themselves and then concertedly hydrogen bonded to carbonyl, phosphate, and glycerol head groups of DMPC are identified. The interface water hydrogen bonded to lipids shows slower relaxation rates for translational and rotational dynamics compared to that of the bulk water and is found to follow sub-diffusive and non-diffusive behaviors, respectively. The mean square displacements and the reorientational auto-correlation functions are slowest for the interfacial waters hydrogen bonded to the carbonyl oxygen since these are buried deep in the hydrophobic core among all interfacial water studied. The intermittent hydrogen bond auto-correlation functions are calculated, which allows breaking and reformations of the hydrogen bonds. The auto-correlation functions for interfacial hydrogen bonded networks develop humps during a transition from cage-like motion to eventual power law behavior of t-3/2. The asymptotic t-3/2 behavior indicates translational diffusion dictated dynamics during hydrogen bond breaking and formation irrespective of the nature of the chemical confinement. Employing reactive flux correlation analysis, the forward rate constant of hydrogen bond breaking and formation is calculated which is used to obtain Gibbs energy of activation of the hydrogen bond breaking. The relaxation rates of the networks buried in the hydrophobic core are slower than the networks near the lipid-water interface which is again slower than bulk due to the higher Gibbs energy of activation. Since hydrogen bond breakage follows a translational diffusion dictated mechanism, chemically confined hydrogen bond networks need an activation energy to diffuse through water depleted hydrophobic environments. Our calculations

  8. Rhodopsin-lipid interactions studied by NMR.

    Science.gov (United States)

    Soubias, Olivier; Gawrisch, Klaus

    2013-01-01

    The biophysical properties of the lipid matrix are known to influence function of integral membrane proteins. We report on a sample preparation method for reconstitution of membrane proteins which uses porous anodic aluminum oxide (AAO) filters with 200-nm-wide pores of high density. The substrate permits formation of tubular, single membranes that line the inner surface of pores. One square centimeter of filter with a thickness of 60μm yields on the order of 500cm(2) of solid-supported single bilayer surface, sufficient for NMR studies. The tubular bilayers are free of detergent, fully hydrated, and accessible for ligands from one side of the membrane. The use of AAO filters greatly improves reproducibility of the reconstitution process such that the influence of protein on lipid order parameters can be studied with high resolution. As an example, results for the G protein-coupled receptor of class A, bovine rhodopsin, are shown. By (2)H NMR order parameter measurements, it is detected that rhodopsin insertion elastically deforms membranes near the protein. Furthermore, by (1)H saturation-transfer NMR under conditions of magic angle spinning, we demonstrate detection of preferences in interactions of rhodopsin with particular lipid species. It is assumed that function of integral membrane proteins depends on both protein-induced elastic deformations of the lipid matrix and preferences for interaction of the protein with particular lipid species in the first layer of lipids surrounding the protein. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Randomized Trial of Desktop Humidifier for Dry Eye Relief in Computer Users.

    Science.gov (United States)

    Wang, Michael T M; Chan, Evon; Ea, Linda; Kam, Clifford; Lu, Yvonne; Misra, Stuti L; Craig, Jennifer P

    2017-11-01

    Dry eye is a frequently reported problem among computer users. Low relative humidity environments are recognized to exacerbate signs and symptoms of dry eye, yet are common in offices of computer operators. Desktop USB-powered humidifiers are available commercially, but their efficacy for dry eye relief has not been established. This study aims to evaluate the potential for a desktop USB-powered humidifier to improve tear-film parameters, ocular surface characteristics, and subjective comfort of computer users. Forty-four computer users were enrolled in a prospective, masked, randomized crossover study. On separate days, participants were randomized to 1 hour of continuous computer use, with and without exposure to a desktop humidifier. Lipid-layer grade, noninvasive tear-film breakup time, and tear meniscus height were measured before and after computer use. Following the 1-hour period, participants reported whether ocular comfort was greater, equal, or lesser than that at baseline. The desktop humidifier effected a relative difference in humidity between the two environments of +5.4 ± 5.0% (P .05). However, a relative increase in the median noninvasive tear-film breakup time of +4.0 seconds was observed in the humidified environment (P computer use.Trial registration no: ACTRN12617000326392.

  10. Meibomian Gland Dysfunction Associated With Periocular Radiotherapy.

    Science.gov (United States)

    Woo, Young Jun; Ko, JaeSang; Ji, Yong Woo; Kim, Tae-Im; Yoon, Jin Sook

    2017-12-01

    To investigate the influence of periocular radiotherapy on meibomian glands. We evaluated 28 patients (40 eyes) who received radiotherapy (RT group) for conjunctival or orbital lymphoma and 30 age-matched control subjects (60 eyes). Subjects underwent slit-lamp examination of the eyelids, Schirmer test, meibography, and evaluation of tear film breakup time (TBUT), Ocular Surface Disease Index (OSDI) scores, meibomian glands evaluation (meiboscore, meibum expressibility, and lid margin abnormality scores), and tear film lipid layer thickness using an ocular surface interferometer. These parameters were compared between subjects in the RT and control groups. Meiboscores as well as meibum expressibility and OSDI scores in the RT group were significantly higher compared with those in the control group (1.6 ± 0.9 vs. 0.4 ± 0.6, 1.6 ± 1.0 vs. 0.2 ± 0.4, and 48.1 ± 21.4 vs. 6.2 ± 4.4, respectively, P radiotherapy exhibited relatively high tear film instability induced by meibomian gland dysfunction, contributing to the high severity of dry eye symptoms.

  11. Study on the lipid organization of stratum corneum lipid models by (cryo-) electron diffraction

    NARCIS (Netherlands)

    Pilgram, GSK; Pelt, AMEV; Oostergetel, GT; Koerten, HK; Bouwstra, JA

    The barrier function of the skin resides in the stratum corneum (SC), This outermost layer consists of protein-rich corneocytes and lipid-rich intercellular domains. These domains form the rate-limiting step for transepidermal water loss and the penetration of substances from the environment. To

  12. Polyene-lipids: a new tool to image lipids

    DEFF Research Database (Denmark)

    Kuerschner, Lars; Ejsing, Christer S.; Ekroos, Kim

    2005-01-01

    conjugated double bonds as a new type of lipid tag. Polyene-lipids exhibit a unique structural similarity to natural lipids, which results in minimal effects on the lipid properties. Analyzing membrane phase partitioning, an important biophysical and biological property of lipids, we demonstrated......Microscopy of lipids in living cells is currently hampered by a lack of adequate fluorescent tags. The most frequently used tags, NBD and BODIPY, strongly influence the properties of lipids, yielding analogs with quite different characteristics. Here, we introduce polyene-lipids containing five...... the superiority of polyene-lipids to both NBD- and BODIPY-tagged lipids. Cells readily take up various polyene-lipid precursors and generate the expected end products with no apparent disturbance by the tag. Applying two-photon excitation microscopy, we imaged the distribution of polyene-lipids in living...

  13. iDEAS: A web-based system for dry eye assessment.

    Science.gov (United States)

    Remeseiro, Beatriz; Barreira, Noelia; García-Resúa, Carlos; Lira, Madalena; Giráldez, María J; Yebra-Pimentel, Eva; Penedo, Manuel G

    2016-07-01

    Dry eye disease is a public health problem, whose multifactorial etiology challenges clinicians and researchers making necessary the collaboration between different experts and centers. The evaluation of the interference patterns observed in the tear film lipid layer is a common clinical test used for dry eye diagnosis. However, it is a time-consuming task with a high degree of intra- as well as inter-observer variability, which makes the use of a computer-based analysis system highly desirable. This work introduces iDEAS (Dry Eye Assessment System), a web-based application to support dry eye diagnosis. iDEAS provides a framework for eye care experts to collaboratively work using image-based services in a distributed environment. It is composed of three main components: the web client for user interaction, the web application server for request processing, and the service module for image analysis. Specifically, this manuscript presents two automatic services: tear film classification, which classifies an image into one interference pattern; and tear film map, which illustrates the distribution of the patterns over the entire tear film. iDEAS has been evaluated by specialists from different institutions to test its performance. Both services have been evaluated in terms of a set of performance metrics using the annotations of different experts. Note that the processing time of both services has been also measured for efficiency purposes. iDEAS is a web-based application which provides a fast, reliable environment for dry eye assessment. The system allows practitioners to share images, clinical information and automatic assessments between remote computers. Additionally, it save time for experts, diminish the inter-expert variability and can be used in both clinical and research settings. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. The evolution of lipids

    Science.gov (United States)

    Itoh, Y. H.; Sugai, A.; Uda, I.; Itoh, T.

    2001-01-01

    Living organisms on the Earth which are divided into three major domains - Archaea, Bacteria, and Eucarya, probably came from a common ancestral cell. Because there are many thermophilic microorganisms near the root of the universal phylogenetic tree, the common ancestral cell should be considered to be a thermophilic microorganism. The existence of a cell is necessary for the living organisms; the cell membrane is the essential structural component of a cell, so its amphiphilic property is vital for the molecule of lipids for cell membranes. Tetraether type glycerophospholipids with C 40 isoprenoid chains are major membrane lipids widely distributed in archaeal cells. Cyclization number of C 40 isoprenoid chains in thermophilic archaea influences the fluidity of lipids whereas the number of carbons and degree of unsaturation in fatty acids do so in bacteria and eucarya. In addition to the cyclization of the tetraether lipids, covalent bonding of two C 40 isoprenoid chains was found in hyperthermophiles. These characteristic structures of the lipids seem to contribute to their fundamental physiological roles in hyperthermophiles. Stereochemical differences between G-1-P archaeal lipids and G-3-P bacterial and eucaryal lipids might have occured by the function of some proteins long after the first cell was developed by the reactions of small organic molecules. We propose that the structure of lipids of the common ancestral cell may have been similar to those of hyperthermophilic archaea.

  15. Lysosomal lipid storage diseases.

    Science.gov (United States)

    Schulze, Heike; Sandhoff, Konrad

    2011-06-01

    Lysosomal lipid storage diseases, or lipidoses, are inherited metabolic disorders in which typically lipids accumulate in cells and tissues. Complex lipids, such as glycosphingolipids, are constitutively degraded within the endolysosomal system by soluble hydrolytic enzymes with the help of lipid binding proteins in a sequential manner. Because of a functionally impaired hydrolase or auxiliary protein, their lipid substrates cannot be degraded, accumulate in the lysosome, and slowly spread to other intracellular membranes. In Niemann-Pick type C disease, cholesterol transport is impaired and unesterified cholesterol accumulates in the late endosome. In most lysosomal lipid storage diseases, the accumulation of one or few lipids leads to the coprecipitation of other hydrophobic substances in the endolysosomal system, such as lipids and proteins, causing a "traffic jam." This can impair lysosomal function, such as delivery of nutrients through the endolysosomal system, leading to a state of cellular starvation. Therapeutic approaches are currently restricted to mild forms of diseases with significant residual catabolic activities and without brain involvement.

  16. Lipid bilayers and interfaces

    NARCIS (Netherlands)

    Kik, R.A.

    2007-01-01

    In biological systems lipid bilayers are subject to many different interactions with other entities. These can range from proteins that are attached to the hydrophilic region of the bilayer or transmembrane proteins that interact with the hydrophobic region of the lipid bilayer. Interaction between

  17. Avanti lipid tools: connecting lipids, technology, and cell biology.

    Science.gov (United States)

    Sims, Kacee H; Tytler, Ewan M; Tipton, John; Hill, Kasey L; Burgess, Stephen W; Shaw, Walter A

    2014-08-01

    Lipid research is challenging owing to the complexity and diversity of the lipidome. Here we review a set of experimental tools developed for the seasoned lipid researcher, as well as, those who are new to the field of lipid research. Novel tools for probing protein-lipid interactions, applications for lipid binding antibodies, enhanced systems for the cellular delivery of lipids, improved visualization of lipid membranes using gold-labeled lipids, and advances in mass spectrometric analysis techniques will be discussed. Because lipid mediators are known to participate in a host of signal transduction and trafficking pathways within the cell, a comprehensive lipid toolbox that aids the science of lipidomics research is essential to better understand the molecular mechanisms of interactions between cellular components. This article is part of a Special Issue entitled Tools to study lipid functions. Copyright © 2014. Published by Elsevier B.V.

  18. Synthesis of Lipidated Proteins.

    Science.gov (United States)

    Mejuch, Tom; Waldmann, Herbert

    2016-08-17

    Protein lipidation is one of the major post-translational modifications (PTM) of proteins. The attachment of the lipid moiety frequently determines the localization and the function of the lipoproteins. Lipidated proteins participate in many essential biological processes in eukaryotic cells, including vesicular trafficking, signal transduction, and regulation of the immune response. Malfunction of these cellular processes usually leads to various diseases such as cancer. Understanding the mechanism of cellular signaling and identifying the protein-protein and protein-lipid interactions in which the lipoproteins are involved is a crucial task. To achieve these goals, fully functional lipidated proteins are required. However, access to lipoproteins by means of standard expression is often rather limited. Therefore, semisynthetic methods, involving the synthesis of lipidated peptides and their subsequent chemoselective ligation to yield full-length lipoproteins, were developed. In this Review we summarize the commonly used methods for lipoprotein synthesis and the development of the corresponding chemoselective ligation techniques. Several key studies involving full-length semisynthetic lipidated Ras, Rheb, and LC3 proteins are presented.

  19. Perspectives on marine zooplankton lipids

    DEFF Research Database (Denmark)

    Kattner, G.; Hagen, W.; Lee, R.F.

    2007-01-01

    We developed new perspectives to identify important questions and to propose approaches for future research on marine food web lipids. They were related to (i) structure and function of lipids, (ii) lipid changes during critical life phases, (iii) trophic marker lipids, and (iv) potential impact...... of climate change. The first addresses the role of lipids in membranes, storage lipids, and buoyancy with the following key question: How are the properties of membranes and deposits affected by the various types of lipids? The second deals with the importance of various types of lipids during reproduction......, development, and resting phases and addresses the role of the different storage lipids during growth and dormancy. The third relates to trophic marker lipids, which are an important tool to follow lipid and energy transfer through the food web. The central question is how can fatty acids be used to identify...

  20. Stratum Corneum Lipids: Their Role for the Skin Barrier Function in Healthy Subjects and Atopic Dermatitis Patients.

    Science.gov (United States)

    van Smeden, Jeroen; Bouwstra, Joke A

    2016-01-01

    Human skin acts as a primary barrier between the body and its environment. Crucial for this skin barrier function is the lipid matrix in the outermost layer of the skin, the stratum corneum (SC). Two of its functions are (1) to prevent excessive water loss through the epidermis and (2) to avoid that compounds from the environment permeate into the viable epidermal and dermal layers and thereby provoke an immune response. The composition of the SC lipid matrix is dominated by three lipid classes: cholesterol, free fatty acids and ceramides. These lipids adopt a highly ordered, 3-dimensional structure of stacked densely packed lipid layers (lipid lamellae): the lateral and lamellar lipid organization. The way in which these lipids are ordered depends on the composition of the lipids. One very common skin disease in which the SC lipid barrier is affected is atopic dermatitis (AD). This review addresses the SC lipid composition and organization in healthy skin, and elaborates on how these parameters are changed in lesional and nonlesional skin of AD patients. Concerning the lipid composition, the changes in the three main lipid classes and the importance of the carbon chain lengths of the lipids are discussed. In addition, this review addresses how these changes in lipid composition induce changes in lipid organization and subsequently correlate with an impaired skin barrier function in both lesional and nonlesional skin of these patients. Furthermore, the effect of filaggrin and mutations in the filaggrin gene on the SC lipid composition is critically discussed. Also, the breakdown products of filaggrin, the natural moisturizing factor molecules and its relation to SC-pH is described. Finally, the paper discusses some major changes in epidermal lipid biosynthesis in patients with AD and other related skin diseases, and how inflammation has a deteriorating effect on the SC lipids and SC biosynthesis. The review ends with perspectives on future studies in relation to

  1. Production of lipids in 10 strains of Chlorella and Parachlorella, and enhanced lipid productivity in Chlorella vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Pribyl, Pavel; Cepak, Vladislav [Academy of Sciences of the Czech Republic, Trebon (Czech Republic). Algological Centre and Centre for Bioindication and Revitalization; Zachleder, Vilem [Academy of Sciences of the Czech Republic, Trebon (Czech Republic). Lab. of the Cell Cycles of Algae

    2012-04-15

    We tested 10 different Chlorella and Parachlorella strains under lipid induction growth conditions in autotrophic laboratory cultures. Between tested strains, substantial differences in both biomass and lipid productivity as well as in the final content of lipids were found. The most productive strain (Chlorella vulgaris CCALA 256) was subsequently studied in detail. The availability of nitrates and/or phosphates strongly influenced growth and accumulation of lipids in cells by affecting cell division. Nutrient limitation substantially enhanced lipid productivity up to a maximal value of 1.5 g l{sup -1} day{sup -1}. We also demonstrated the production of lipids through large-scale cultivation of C. vulgaris in a thin layer photobioreactor, even under suboptimal conditions. After 8 days of cultivation, maximal lipid productivity was 0.33 g l{sup -1} day{sup -1}, biomass density was 5.7 g l{sup -1} dry weight and total lipid content was more than 30% dry weight. C. vulgaris lipids comprise fatty acids with a relatively high degree of saturation compared with canola oil offering a possible alternative to the use of higher plant oils. (orig.)

  2. Sebum/Meibum Surface Film Interactions and Phase Transitional Differences

    OpenAIRE

    Mudgil, Poonam; Borchman, Douglas; Gerlach, Dylan; Yappert, Marta C.

    2016-01-01

    Purpose Sebum may contribute to the composition of the tear film lipid layer naturally or as a contaminant artifact from collection. The aims of this study were to determine: if sebum changes the rheology of meibum surface films; if the resonance near 5.2 ppm in the 1H-NMR spectra of sebum is due to squalene (SQ); and if sebum or SQ, a major component of sebum, interacts with human meibum. Methods Human meibum was collected from the lid margin with a platinum spatula. Human sebum was collecte...

  3. Structural characterization and lipid composition of acquired cholesteatoma

    DEFF Research Database (Denmark)

    Bloksgaard, Maria; Svane-Knudsen, Viggo; Sørensen, Jens A

    2012-01-01

    HYPOTHESIS: The goal of this work is to characterize the morphology and lipid composition of acquired cholesteatoma. We hypothesize that constitutive lipid membranes are present in the cholesteatoma and resemble those found in human skin stratum corneum. METHODS: We performed a comparative...... noninvasive structural and lipid compositional study of acquired cholesteatoma and control human skin using multiphoton excitation fluorescence microscopy-related techniques and high-performance thin-layer chromatography. RESULTS: The structural arrangement of the cholesteatoma is morphologically invariant...... along a depth of more than 200 μm and resembles the stratum corneum of hyperorthokeratotic skin. Lipid compositional analyses of the cholesteatoma show the presence of all major lipid classes found in normal skin stratum corneum (ceramides, long chain fatty acids, and cholesterol). Consistent with this...

  4. Induced videokeratography alterations in patients with excessive meibomian secretions.

    Science.gov (United States)

    Markomanolakis, Marinos M; Kymionis, George D; Aslanides, Ioannis M; Astyrakakis, Nikolaos; Pallikaris, Ioannis G

    2005-01-01

    To describe lipid-induced specific videokeratographic (VKG) corneal changes and subsequent resolution after eyelid washing. VKG was performed with C-Scan corneal topography. In all patients an excessive meibomian gland lipid secretion was found with or without coexistent chronic posterior blepharitis. After the initial VKG, a meticulous cleaning of the lids with a mild alkali shampoo (10% Johnson's baby shampoo in sterile water) was done, first by gently scrubbing the closed eyelid fissure with the solution to mobilize and emulsify any Meibomian gland secretions followed by cleaning of the upper and lower margins individually, using Q-tip applicators soaked in the detergent. Three patients with tear film lipid layer excess (TFLE), which correlated with the presence of a superior or central corneal steepening in VKG, were studied. In two of the subjects, careful lid washing reversed either completely or partially this VKG effect, whereas in the last patient the VKG changes after artificially increasing the tear film lipid content is described. Meibomian gland lipid secretions may induce mainly superior and occasionally central VKG corneal steepening that is not correlated with any slit-lamp pathologic findings. Computerized corneal topography can help detect such corneal abnormalities, and their reversibility may distinguish them from other pathologic conditions (such as contact lens-induced warpage, eccentric ablations, irregular astigmatism, superior keratoconus).

  5. Lipid extraction from microalgae using a single ionic liquid

    Science.gov (United States)

    Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

    2013-05-28

    A one-step process for the lysis of microalgae cell walls and separation of the cellular lipids for use in biofuel production by utilizing a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium. The hydrophilic ionic liquid both lyses the microalgae cell walls and forms two immiscible layers, one of which consists of the lipid contents of the lysed cells. After mixture of the hydrophilic ionic liquid with a suspension of microalgae cells, gravity causes a hydrophobic lipid phase to move to a top phase where it is removed from the mixture and purified. The hydrophilic ionic liquid is recycled to lyse new microalgae suspensions.

  6. Zebrafish Embryonic Lipidomic Analysis Reveals that the Yolk Cell Is Metabolically Active in Processing Lipid

    Directory of Open Access Journals (Sweden)

    Daniel Fraher

    2016-02-01

    Full Text Available The role of lipids in providing energy and structural cellular components during vertebrate development is poorly understood. To elucidate these roles further, we visualized lipid deposition and examined expression of key lipid-regulating genes during zebrafish embryogenesis. We also conducted a semiquantitative analysis of lipidomic composition using liquid chromatography (LC-mass spectrometry. Finally, we analyzed processing of boron-dipyrromethene (BODIPY lipid analogs injected into the yolk using thin layer chromatography. Our data reveal that the most abundant lipids in the embryo are cholesterol, phosphatidylcholine, and triglyceride. Moreover, we demonstrate that lipids are processed within the yolk prior to mobilization to the embryonic body. Our data identify a metabolically active yolk and body resulting in a dynamic lipid composition. This provides a foundation for studying lipid biology during normal or pharmacologically compromised embryogenesis.

  7. What Is Dry Eye?

    Medline Plus

    Full Text Available ... right type of tears or tear film . How do tears work? When you blink, a film of ... layer cleans the eye, washing away particles that do not belong in the eye. This layer comes ...

  8. Interaction of antimicrobial peptides with lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Hanulova, Maria

    2008-12-15

    This study aims to investigate the difference in the interaction of antimicrobial peptides with two classes of zwitterionic peptides, phosphatidylethanolamines (PE) and phosphatidylcholines (PC). Further experiments were performed on model membranes prepared from specific bacterial lipids, lipopolysaccharides (LPS) isolated from Salmonella minnesota. The structure of the lipid-peptide aqueous dispersions was studied by small-and wide-angle X-ray diffraction during heating and cooling from 5 to 85 C. The lipids and peptides were mixed at lipid-to-peptide ratios 10-10000 (POPE and POPC) or 2-50 (LPS). All experiments were performed at synchrotron soft condensed matter beamline A2 in Hasylab at Desy in Hamburg, Germany. The phases were identified and the lattice parameters were calculated. Alamethicin and melittin interact in similar ways with the lipids. Pure POPC forms only lamellar phases. POPE forms lamellar phases at low temperatures that upon heating transform into a highly curved inverse hexagonal phase. Insertion of the peptide induced inverse bicontinuous cubic phases which are an ideal compromise between the curvature stress and the packing frustration. Melittin usually induced a mixture of two cubic phases, Im3m and Pn3m, with a ratio of lattice parameters close to 1.279, related to the underlying minimal surfaces. They formed during the lamellar to hexagonal phase transition and persisted during cooling till the onset of the gel phase. The phases formed at different lipid-to-peptide ratios had very similar lattice parameters. Epitaxial relationships existed between coexisting cubic phases and hexagonal or lamellar phases due to confinement of all phases to an onion vesicle, a vesicle with several layers consisting of different lipid phases. Alamethicin induced the same cubic phases, although their formation and lattice parameters were dependent on the peptide concentration. The cubic phases formed during heating from the lamellar phase and their onset

  9. Interaction of antimicrobial peptides with lipid membranes

    International Nuclear Information System (INIS)

    Hanulova, Maria

    2008-12-01

    This study aims to investigate the difference in the interaction of antimicrobial peptides with two classes of zwitterionic peptides, phosphatidylethanolamines (PE) and phosphatidylcholines (PC). Further experiments were performed on model membranes prepared from specific bacterial lipids, lipopolysaccharides (LPS) isolated from Salmonella minnesota. The structure of the lipid-peptide aqueous dispersions was studied by small-and wide-angle X-ray diffraction during heating and cooling from 5 to 85 C. The lipids and peptides were mixed at lipid-to-peptide ratios 10-10000 (POPE and POPC) or 2-50 (LPS). All experiments were performed at synchrotron soft condensed matter beamline A2 in Hasylab at Desy in Hamburg, Germany. The phases were identified and the lattice parameters were calculated. Alamethicin and melittin interact in similar ways with the lipids. Pure POPC forms only lamellar phases. POPE forms lamellar phases at low temperatures that upon heating transform into a highly curved inverse hexagonal phase. Insertion of the peptide induced inverse bicontinuous cubic phases which are an ideal compromise between the curvature stress and the packing frustration. Melittin usually induced a mixture of two cubic phases, Im3m and Pn3m, with a ratio of lattice parameters close to 1.279, related to the underlying minimal surfaces. They formed during the lamellar to hexagonal phase transition and persisted during cooling till the onset of the gel phase. The phases formed at different lipid-to-peptide ratios had very similar lattice parameters. Epitaxial relationships existed between coexisting cubic phases and hexagonal or lamellar phases due to confinement of all phases to an onion vesicle, a vesicle with several layers consisting of different lipid phases. Alamethicin induced the same cubic phases, although their formation and lattice parameters were dependent on the peptide concentration. The cubic phases formed during heating from the lamellar phase and their onset

  10. Adsorption of apo- and holo-tear lipocalin to a bovine Meibomian lipid film.

    Science.gov (United States)

    Mudgil, Poonam; Millar, Thomas J

    2008-04-01

    Adsorption of apo- and holo-tear lipocalin (Tlc) to bovine Meibomian lipid film was studied. A Langmuir trough was used for these studies and the adsorption of protein was observed by recording changes in the pressure with time (pi-T profile). The films were photographed at different stages of adsorption by doping Meibomian lipids with a fluorescently tagged lipid. The results indicated that apo-Tlc adsorbed much more quickly than holo-Tlc to the Meibomian lipid film. Contrary to the expectation that holo-Tlc would release lipids to the surface and surface pressure would be higher, it was found that the surface pressure was higher with the adsorption of apo-Tlc to the surface. Photography of the films showed that apo- and holo-Tlc interacted differently with the Meibomian lipid layer. Adsorption of holo-Tlc resulted in big bright patches and adsorption of apo-Tlc resulted in many small patches along with the big patches. Both forms of Tlc produced a more stable film as indicated by decreased movement of the protein adsorbed films, and a higher maximum surface pressure upon compression of these films compared with Meibomian lipid films alone. Isocyles of apo-Tlc adsorbed films gave a higher surface pressure than that of holo-Tlc. From these results, it is concluded that both apo- and holo-Tlc adsorbed to the Meibomian lipid layer and the delivery of the lipids from Tlc to the outer lipid layer could not be detected by our techniques. Its scavenging role to remove lipids from the corneal surface and bind with them might be beneficial for increasing tear viscosity but whether those lipids are delivered to the outermost lipid layer still remains unclear.

  11. Lipid Cell Biology: A Focus on Lipids in Cell Division.

    Science.gov (United States)

    Storck, Elisabeth M; Özbalci, Cagakan; Eggert, Ulrike S

    2018-06-20

    Cells depend on hugely diverse lipidomes for many functions. The actions and structural integrity of the plasma membrane and most organelles also critically depend on membranes and their lipid components. Despite the biological importance of lipids, our understanding of lipid engagement, especially the roles of lipid hydrophobic alkyl side chains, in key cellular processes is still developing. Emerging research has begun to dissect the importance of lipids in intricate events such as cell division. This review discusses how these structurally diverse biomolecules are spatially and temporally regulated during cell division, with a focus on cytokinesis. We analyze how lipids facilitate changes in cellular morphology during division and how they participate in key signaling events. We identify which cytokinesis proteins are associated with membranes, suggesting lipid interactions. More broadly, we highlight key unaddressed questions in lipid cell biology and techniques, including mass spectrometry, advanced imaging, and chemical biology, which will help us gain insights into the functional roles of lipids.

  12. Pharmacogenetics of lipid diseases

    Directory of Open Access Journals (Sweden)

    Ordovas Jose M

    2004-01-01

    Full Text Available Abstract The genetic basis for most of the rare lipid monogenic disorders have been elucidated, but the challenge remains in determining the combination of genes that contribute to the genetic variability in lipid levels in the general population; this has been estimated to be in the range of 40-60 per cent of the total variability. Therefore, the effect of common polymorphisms on lipid phenotypes will be greatly modulated by gene-gene and gene-environment interactions. This approach can also be used to characterise the individuality of the response to lipid-lowering therapies, whether using drugs (pharmacogenetics or dietary interventions (nutrigenetics. In this regard, multiple studies have already described significant interactions between candidate genes for lipid and drug metabolism that modulate therapeutic response--although the outcomes of these studies have been controversial and call for more rigorous experimental design and analytical approaches. Once solid evidence about the predictive value of genetic panels is obtained, risk and therapeutic algorithms can begin to be generated that should provide an accurate measure of genetic predisposition, as well as targeted behavioural modifications or drugs of choice and personalised dosages of these drugs.

  13. Effects of cadmium on lipids of almond seedlings (Prunus dulcis).

    Science.gov (United States)

    Elloumi, Nada; Zouari, Mohamed; Chaari, Leila; Jomni, Chiraz; Marzouk, Brahim; Ben Abdallah, Ferjani

    2014-12-01

    Cadmium uptake and distribution, as well as its effects on lipid composition was investigated in almond seedlings (Prunus dulcis) grown in culture solution supplied with two concentrations of Cd (50 and 150 μM). The accumulation of Cd increased with external metal concentrations, and was considerably higher in roots than in leaves. Fourteen days after Cd treatment, the membrane lipids were extracted and separated on silica-gel thin layer chromatography (TLC). Fatty acid methyl esters were analyzed by FID-GC on a capillary column. Our results showed that Cd stress decreased the quantities of all lipids classes (phospholipids, galactolipids and neutral lipids). Galactolipid, phospholipid and neutral lipid concentrations decreased more in roots than in leaves by Cd-treatment. In almost all lipid classes the proportion of palmitic acid (16:0), linoleic (18: 2) and that of linolenic (18: 3) acid decreased, suggesting that heavy metal treatment induced an alteration in the fatty acid synthesis processes. In conclusion, our results show that the changes found in total fatty acids, in the quantities of all lipids classes, and in the in the profiles of individual polar lipids suggest that membrane structure and function might be altered by Cd stress.

  14. Lipids, lipid bilayers and vesicles as seen by neutrons

    International Nuclear Information System (INIS)

    Seto, Hideki

    2011-01-01

    Lipid molecules self-assemble into bilayers in water with their hydrocarbon chains facing inward due to their amphiphilic nature. The structural and dynamical properties of lipids and lipid bilayers have been studied by neutron scattering intensively. In this article, 3 topics are shown as typical examples. 1) a time-resolved small-angle neutron scattering on uni-lamellar vesicles composed of deuterated and protonated lipids to determine lipid kinetics, 2) small-angle neutron scattering to investigate spontaneous formation of nanopores on uni-lamellar vesicles, and 3) neutron spin echo study to determine bending modulus of lipid bilayers. (author)

  15. Lipid management in ramadan.

    Science.gov (United States)

    Slim, Ines; Ach, Koussay; Chaieb, Larbi

    2015-05-01

    During Ramadan fast, Muslims must refrain from smoking, eating, drinking, having sexual activity, and consuming oral medications from sunrise to sunset. It has been previously shown that Ramadan fasting induces favourable changes on metabolic parameters, reduces oxidative stress and inflammation and promotes cardiovascular benefits. Although ill people are exempted from fasting, most patients with chronic diseases are keen on performing this Islamic-ritual. During recent years, Risk stratification and treatment adjustment during Ramadan are well known and structured in several guidelines for patients with diabetes mellitus. Data related to the effect of Ramadan fast on lipid profiles are less known and several controversies have been reported. Here, we focus on lipid profile and lipid management during Ramadan taking into account comorbidities and cardiovascular risk.

  16. Heart, lipids and hormones

    Directory of Open Access Journals (Sweden)

    Peter Wolf

    2017-05-01

    Full Text Available Cardiovascular disease is the leading cause of death in general population. Besides well-known risk factors such as hypertension, impaired glucose tolerance and dyslipidemia, growing evidence suggests that hormonal changes in various endocrine diseases also impact the cardiac morphology and function. Recent studies highlight the importance of ectopic intracellular myocardial and pericardial lipid deposition, since even slight changes of these fat depots are associated with alterations in cardiac performance. In this review, we overview the effects of hormones, including insulin, thyroid hormones, growth hormone and cortisol, on heart function, focusing on their impact on myocardial lipid metabolism, cardiac substrate utilization and ectopic lipid deposition, in order to highlight the important role of even subtle hormonal changes for heart function in various endocrine and metabolic diseases.

  17. The Mediator Complex and Lipid Metabolism.

    Science.gov (United States)

    Zhang, Yi; Xiaoli; Zhao, Xiaoping; Yang, Fajun

    2013-03-01

    The precise control of gene expression is essential for all biological processes. In addition to DNA-binding transcription factors, numerous transcription cofactors contribute another layer of regulation of gene transcription in eukaryotic cells. One of such transcription cofactors is the highly conserved Mediator complex, which has multiple subunits and is involved in various biological processes through directly interacting with relevant transcription factors. Although the current understanding on the biological functions of Mediator remains incomplete, research in the past decade has revealed an important role of Mediator in regulating lipid metabolism. Such function of Mediator is dependent on specific transcription factors, including peroxisome proliferator-activated receptor-gamma (PPARγ) and sterol regulatory element-binding proteins (SREBPs), which represent the master regulators of lipid metabolism. The medical significance of these findings is apparent, as aberrant lipid metabolism is intimately linked to major human diseases, such as type 2 diabetes and cardiovascular disease. Here, we briefly review the functions and molecular mechanisms of Mediator in regulation of lipid metabolism.

  18. Factors influencing particulate lipid production in the East Atlantic Ocean

    Science.gov (United States)

    Gašparović, B.; Frka, S.; Koch, B. P.; Zhu, Z. Y.; Bracher, A.; Lechtenfeld, O. J.; Neogi, S. B.; Lara, R. J.; Kattner, G.

    2014-07-01

    Extensive analyses of particulate lipids and lipid classes were conducted to gain insight into lipid production and related factors along the biogeochemical provinces of the Eastern Atlantic Ocean. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a), phaeopigments, Chl a concentrations and carbon content of eukaryotic micro-, nano- and picophytoplankton, including cell abundances for the latter two and for cyanobacteria and prokaryotic heterotrophs. We focused on the productive ocean surface (2 m depth and deep Chl a maximum (DCM). Samples from the deep ocean provided information about the relative reactivity and preservation potential of particular lipid classes. Surface and DCM particulate lipid concentrations (3.5-29.4 μg L-1) were higher than in samples from deep waters (3.2-9.3 μg L-1) where an increased contribution to the POC pool was observed. The highest lipid concentrations were measured in high latitude temperate waters and in the North Atlantic Tropical Gyral Province (13-25°N). Factors responsible for the enhanced lipid synthesis in the eastern Atlantic appeared to be phytoplankton size (micro, nano, pico) and the low nutrient status with microphytoplankton having the most expressed influence in the surface and eukaryotic nano- and picophytoplankton in the DCM layer. Higher lipid to Chl a ratios suggest enhanced lipid biosynthesis in the nutrient poorer regions. The various lipid classes pointed to possible mechanisms of phytoplankton adaptation to the nutritional conditions. Thus, it is likely that adaptation comprises the replacement of membrane phospholipids by non-phosphorus containing glycolipids under low phosphorus conditions. The qualitative and quantitative lipid compositions revealed that phospholipids were the most degradable lipids, and their occurrence decreased with increasing depth. In contrast, wax esters, possibly originating from zooplankton, survived downward transport probably due to the fast sinking

  19. Dietary conjugated linoleic acids affect tissue lipid composition but not de novo lipogenesis in finishing pigs

    OpenAIRE

    Bee , Giuseppe

    2001-01-01

    International audience; Dietary conjugated linoleic acids (CLA) have been reported to profoundly affect lipid metabolism and to act as repartitioning agents. Currently, little is known about their effect on the fatty acid profile of tissue lipids in pigs. In the present study we determined the lipid composition of the backfat inner (BFI) and outer layer (BFO), omental fat (OF) and intramuscular fat (IMF) of the longissimus dorsi muscle in 24 Swiss Large White pigs fed diets supplemented eithe...

  20. A trough for improved SFG spectroscopy of lipid monolayers

    Science.gov (United States)

    Franz, Johannes; van Zadel, Marc-Jan; Weidner, Tobias

    2017-05-01

    Lipid monolayers are indispensable model systems for biological membranes. The main advantage over bilayer model systems is that the surface pressure within the layer can be directly and reliably controlled. The sensitive interplay between surface pressure and temperature determines the molecular order within a model membrane and consequently determines the membrane phase behavior. The lipid phase is of crucial importance for a range of membrane functions such as protein interactions and membrane permeability. A very reliable method to probe the structure of lipid monolayers is sum frequency generation (SFG) vibrational spectroscopy. Not only is SFG extremely surface sensitive but it can also directly access critical parameters such as lipid order and orientation, and it can provide valuable information about protein interactions along with interfacial hydration. However, recent studies have shown that temperature gradients caused by high power laser beams perturb the lipid layers and potentially obscure the spectroscopic results. Here we demonstrate how the local heating problem can be effectively reduced by spatially distributing the laser pulses on the sample surface using a translating Langmuir trough for SFG experiments at lipid monolayers. The efficiency of the trough is illustrated by the detection of enhanced molecular order due to reduced heat load.

  1. Lipid storage myopathies.

    Science.gov (United States)

    Bruno, Claudio; Dimauro, Salvatore

    2008-10-01

    The aim of this review is to provide an update on disorders of lipid metabolism affecting skeletal muscle exclusively or predominantly and to summarize recent clinical, genetic, and therapeutic studies in this field. Over the past 5 years, new clinical phenotypes and genetic loci have been described, unusual pathogenic mechanisms have been elucidated, and novel pharmacological approaches have been developed. At least one genetic defect responsible for the myopathic form of CoQ10 deficiency has been identified, causing a disorder that is allelic with the late-onset riboflavine-responsive form of multiple acyl-coenzyme A dehydrogenation deficiency. Novel mechanisms involved in the lipolytic breakdown of cellular lipid depots have been described and have led to the identification of genes and mutations responsible for multisystemic neutral lipid storage disorders, characterized by accumulation of triglyceride in multiple tissues, including muscle. Defects in lipid metabolism can affect either the mitochondrial transport and oxidation of exogenous fatty acid or the catabolism of endogenous triglycerides. These disorders impair energy production and almost invariably involve skeletal muscle, causing progressive myopathy with muscle weakness, or recurrent acute episodes of rhabdomyolysis triggered by exercise, fasting, or infections. Clinical and genetic characterization of these disorders has important implications both for accurate diagnostic approach and for development of therapeutic strategies.

  2. Exogenous lipid pneumonia

    International Nuclear Information System (INIS)

    Bernasconi, A.; Gavelli, G.; Zompatori, M.; Galleri, C.; Zanasi, A.; Fabbri, M.; Bazzocchi, F.

    1988-01-01

    Exogenous lipid pneumonia (ELP) is caused by the aspiration of animal, vegetal or, more often, mineral oils. Even though it may also be acute, ELP is most frequently a chronic disease, affecting people with predisposing factors, such as neuromuscular disorders, structural abnormalities and so on; very often exogenous lipid pneumonia is found in tracheotomized patients. The pathology of lipid pneumonia is a chronic inflammatory process evolving in foreign-body-like reaction, and eventually in ''end-stage lung'' condition. Clinically, most patients are asymptomatic; few cases only present with cough, dyspnea and chest pain. Eight cases of ELP, studied over the past 3 years, are described in this paper. All the patients were examined by chest radiographs and standard tomograms; 3 patients underwent CT. X-ray features were mono/bilateral consolidation of the lower zones, with air bronchogram and variable reduction in volume. CT density was not specific for fat tissue. In all cases the diagnosis was confirmed at biopsy. In 5 patients, followed for at least one year, clinical-radiological features showed no change. Thus, complications of ELP (especially malignant evolution) could be excluded. The authors conclude that lipid pneumonia must be considered in differential diagnosis of patients with history of usage of oils and compatible X-ray findings. The usefulness of an accurate follow-up is stressed

  3. Lipid Therapy for Intoxications

    NARCIS (Netherlands)

    Robben, Joris Henricus; Dijkman, Marieke Annet

    This review discusses the use of intravenous lipid emulsion (ILE) in the treatment of intoxications with lipophilic agents in veterinary medicine. Despite growing scientific evidence that ILE has merit in the treatment of certain poisonings, there is still uncertainty on the optimal composition of

  4. Lipid Therapy for Intoxications

    NARCIS (Netherlands)

    Robben, Joris Henricus; Dijkman, Marieke Annet

    2017-01-01

    This review discusses the use of intravenous lipid emulsion (ILE) in the treatment of intoxications with lipophilic agents in veterinary medicine. Despite growing scientific evidence that ILE has merit in the treatment of certain poisonings, there is still uncertainty on the optimal composition of

  5. Lipid composition of the stratum corneum and cutaneous water loss in birds along an aridity gradient

    NARCIS (Netherlands)

    Champagne, Alex M.; Munoz-Garcia, Agusti; Shtayyeh, Tamer; Tieleman, B. Irene; Hegemann, Arne; Clement, Michelle E.; Williams, Joseph B.

    2012-01-01

    Intercellular and covalently bound lipids within the stratum corneum (SC), the outermost layer of the epidermis, are the primary barrier to cutaneous water loss (CWL) in birds. We compared CWL and intercellular SC lipid composition in 20 species of birds from desert and mesic environments.

  6. Big, Fat World of Lipids

    Science.gov (United States)

    ... offered a more quantitative and systematic approach to lipids research. Much of the effort has been led by a research consortium called LIPID MAPS. With funding from the National Institutes of ...

  7. Amphotericin B Lipid Complex Injection

    Science.gov (United States)

    Amphotericin B lipid complex injection is used to treat serious, possibly life-threatening fungal infections in people who did ... respond or are unable to tolerate conventional amphotericin B therapy. Amphotericin B lipid complex injection is in ...

  8. Differential distribution of lipids in epidermis, gastrodermis and hosted Symbiodinium in the sea anemone Anemonia viridis.

    Science.gov (United States)

    Revel, Johana; Massi, Lionel; Mehiri, Mohamed; Boutoute, Marc; Mayzaud, Patrick; Capron, Laure; Sabourault, Cécile

    2016-01-01

    Cnidarian-dinoflagellate symbiosis mainly relies on nutrient recycling, thus providing both partners with a competitive advantage in nutrient-poor waters. Essential processes related to lipid metabolism can be influenced by various factors, including hyperthermal stress. This can affect the lipid content and distribution in both partners, while contributing to symbiosis disruption and bleaching. In order to gain further insight into the role and distribution of lipids in the cnidarian metabolism, we investigated the lipid composition of the sea anemone Anemonia viridis and its photosynthetic dinoflagellate endosymbionts (Symbiodinium). We compared the lipid content and fatty acid profiles of the host cellular layers, non-symbiotic epidermal and symbiont-containing gastrodermal cells, and those of Symbiodinium, in a mass spectrometry-based assessment. Lipids were more concentrated in Symbiodinium cells, and the lipid class distribution was dominated by polar lipids in all tissues. The fatty acid distribution between host cell layers and Symbiodinium cells suggested potential lipid transfers between the partners. The lipid composition and distribution was modified during short-term hyperthermal stress, mainly in Symbiodinium cells and gastrodermis. Exposure to elevated temperature rapidly caused a decrease in polar lipid C18 unsaturated fatty acids and a strong and rapid decrease in the abundance of polar lipid fatty acids relative to sterols. These lipid indicators could therefore be used as sensitive biomarkers to assess the physiology of symbiotic cnidarians, especially the effect of thermal stress at the onset of cnidarian bleaching. Overall, the findings of this study provide some insight on key lipids that may regulate maintenance of the symbiotic interaction. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Layered materials

    Science.gov (United States)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  10. Skin lipid structure controls water permeability in snake molts.

    Science.gov (United States)

    Torri, Cristian; Mangoni, Alfonso; Teta, Roberta; Fattorusso, Ernesto; Alibardi, Lorenzo; Fermani, Simona; Bonacini, Irene; Gazzano, Massimo; Burghammer, Manfred; Fabbri, Daniele; Falini, Giuseppe

    2014-01-01

    The role of lipids in controlling water exchange is fundamentally a matter of molecular organization. In the present study we have observed that in snake molt the water permeability drastically varies among species living in different climates and habitats. The analysis of molts from four snake species: tiger snake, Notechis scutatus, gabon viper, Bitis gabonica, rattle snake, Crotalus atrox, and grass snake, Natrix natrix, revealed correlations between the molecular composition and the structural organization of the lipid-rich mesos layer with control in water exchange as a function of temperature. It was discovered, merging data from micro-diffraction and micro-spectroscopy with those from thermal, NMR and chromatographic analyses, that this control is generated from a sophisticated structural organization that changes size and phase distribution of crystalline domains of specific lipid molecules as a function of temperature. Thus, the results of this research on four snake species suggest that in snake skins different structured lipid layers have evolved and adapted to different climates. Moreover, these lipid structures can protect, "safety", the snakes from water lost even at temperatures higher than those of their usual habitat. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Unraveling lipid metabolism in lipid-dependent pathogenic Malassezia yeasts

    OpenAIRE

    Celis Ramirez, A.M.

    2017-01-01

    Malassezia yeasts are lipid-dependent fungal species that are common members of the human and animal skin microbiota. The lipid-dependency is a crucial trait in the adaptation process to grow on the skin but also plays a role in their pathogenic life style. Malassezia species can cause several skin infections like dandruff or seborrheic dermatitis but also bloodstream infections. Understanding the lipid metabolism in Malassezia is essential to understand its life style as skin commensal and p...

  12. Original Article Effect of Soft Contact Lens Materials on Tear Film ...

    African Journals Online (AJOL)

    problems, results in intolerance of contact lens wear and damage (Foulks, ... reported that contact lens-related dry eye may be ... eliminating or modifying the refractive error ..... risk of eye infection, easier handling due to ... Adv Exp Med Biol.

  13. Treatment of the Cornea Using Transcytotic Delivery into the Tear Film

    Science.gov (United States)

    2015-12-01

    following popular refractive proce- dures, such as photorefractive keratectomy ( PRK ) and laser in situ keratomileusis ( LASIK ), directly rely on the...chronic inflammation of the eyelid) vs . normal tears [9]. LG-targeted delivery of this therapeutic within our novel delivery system is chosen for...particle compared to SI. If so, this might result from a larger hydro- philic fraction for KSI (66% vs . 48% for SI), which could result in a larger radius of

  14. Ultrastructural study on dynamics of lipid bodies and plastids during ripening of chili pepper fruits.

    Science.gov (United States)

    Liu, Lin

    2013-03-01

    Dynamics of lipid bodies and plastids in chili pepper fruits during ripening were investigated by means of transmission electron microscopy. Mesocarp of chili pepper fruits consists of collenchyma, normal parenchyma, and huge celled parenchyma. In mature green fruits, plastids contain numerous thylakoids that are well organized into grana in collenchyma, a strikingly huge amount of starch and irregularly organized thylakoids in normal parenchyma, and simple tubes rather than thylakoids in huge celled parenchyma. These morphological features suggest that plastids are chloroplasts in collenchyma, chloroamyloplasts in normal parenchyma, proplastids in huge celled parenchyma. As fruits ripen to red, plastids in all cell types convert to chromoplasts and, concomitantly, lipid bodies accumulate in both cytoplasm and chromoplasts. Cytosolic lipid bodies are lined up in a regular layer adjacent to plasma membrane. The cytosolic lipid body consists of a core surrounded by a membrane. The core is comprised of a more electron-dense central part enclosed by a slightly less electron-dense peripheral layer. Plastidial lipid bodies in collenchyma, normal parenchyma, and endodermis initiate as plastoglobuli, which in turn convert to rod-like structures. Therefore, plastidial lipid bodies are more dynamic than cytosolic lipid bodies. Both cytosolic and plastidial lipid bodies contain rich unsaturated lipids. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Self-assembled tethered bimolecular lipid membranes.

    Science.gov (United States)

    Sinner, Eva-Kathrin; Ritz, Sandra; Naumann, Renate; Schiller, Stefan; Knoll, Wolfgang

    2009-01-01

    This chapter describes some of the strategies developed in our group for designing, constructing and structurally and functionally characterizing tethered bimolecular lipid membranes (tBLM). We introduce this platform as a novel model membrane system that complements the existing ones, for example, Langmuir monolayers, vesicular liposomal dispersions and bimolecular ("black") lipid membranes. Moreover, it offers the additional advantage of allowing for studies of the influence of membrane structure and order on the function of integral proteins, for example, on how the composition and organization of lipids in a mixed membrane influence the ion translocation activity of integral channel proteins. The first strategy that we introduce concerns the preparation of tethered monolayers by the self-assembly of telechelics. Their molecular architecture with a headgroup, a spacer unit (the "tether") and the amphiphile that mimics the lipid molecule allows them to bind specifically to the solid support thus forming the proximal layer of the final architecture. After fusion of vesicles that could contain reconstituted proteins from a liposomal dispersion in contact to this monolayer the tethered bimolecular lipid membrane is obtained. This can then be characterized by a broad range of surface analytical techniques, including surface plasmon spectroscopies, the quartz crystal microbalance, fluorescence and IR spectroscopies, and electrochemical techniques, to mention a few. It is shown that this concept allows for the construction of tethered lipid bilayers with outstanding electrical properties including resistivities in excess of 10 MOmega cm2. A modified strategy uses the assembly of peptides as spacers that couple covalently via their engineered sulfhydryl or lipoic acid groups at the N-terminus to the employed gold substrate, while their C-terminus is being activated afterward for the coupling of, for example, dimyristoylphosphatidylethanol amine (DMPE) lipid molecules

  16. Probing lipid membrane electrostatics

    Science.gov (United States)

    Yang, Yi

    The electrostatic properties of lipid bilayer membranes play a significant role in many biological processes. Atomic force microscopy (AFM) is highly sensitive to membrane surface potential in electrolyte solutions. With fully characterized probe tips, AFM can perform quantitative electrostatic analysis of lipid membranes. Electrostatic interactions between Silicon nitride probes and supported zwitterionic dioleoylphosphatidylcholine (DOPC) bilayer with a variable fraction of anionic dioleoylphosphatidylserine (DOPS) were measured by AFM. Classical Gouy-Chapman theory was used to model the membrane electrostatics. The nonlinear Poisson-Boltzmann equation was numerically solved with finite element method to provide the potential distribution around the AFM tips. Theoretical tip-sample electrostatic interactions were calculated with the surface integral of both Maxwell and osmotic stress tensors on tip surface. The measured forces were interpreted with theoretical forces and the resulting surface charge densities of the membrane surfaces were in quantitative agreement with the Gouy-Chapman-Stern model of membrane charge regulation. It was demonstrated that the AFM can quantitatively detect membrane surface potential at a separation of several screening lengths, and that the AFM probe only perturbs the membrane surface potential by external field created by the internai membrane dipole moment. The analysis yields a dipole moment of 1.5 Debye per lipid with a dipole potential of +275 mV for supported DOPC membranes. This new ability to quantitatively measure the membrane dipole density in a noninvasive manner will be useful in identifying the biological effects of the dipole potential. Finally, heterogeneous model membranes were studied with fluid electric force microscopy (FEFM). Electrostatic mapping was demonstrated with 50 nm resolution. The capabilities of quantitative electrostatic measurement and lateral charge density mapping make AFM a unique and powerful

  17. Biosynthesis of lipids by bovine meibomian glands

    International Nuclear Information System (INIS)

    Kolattukudy, P.E.; Rogers, L.M.; Nicolaides, N.

    1985-01-01

    Isolated bovine meibomian glands incorporated exogenous [1- 14 C]acetate into lipids. Thin layer chromatographic analysis of the lipids showed that wax esters and sterol esters contained 61% of the total label. Radio gas liquid chromatographic analysis of the acid and alcohol moieties of both ester fractions showed the label was distributed equally between the two portions of the ester in both cases. Cholesterol and 5-alpha-cholest-7-en-3 beta-ol were the major labeled sterols, and anteiso-C25, anteiso-C27 and anteiso-C23 were the most highly labeled alcohols. The major labeled fatty acids in the wax esters were anteiso-C15, n-C16, anteiso-C17 and n-C18:1, whereas anteiso-C25 and anteiso-C27 were the major labeled acids in the sterol esters. The diester region with 6% of the total label contained labeled fatty acids and fatty alcohols each with anteiso-C25 as the major component and omega-hydroxy acids in which n-C32:1 was the major labeled component. The triglyceride fraction which contained 8% of the total lipids was composed of labeled fatty acids similar to those found in both sterol and wax ester fractions. Chromatographic analyses of the labeled lipids derived from exogenous labeled isoleucine showed that anteiso-branched products were preferentially labeled. The labeled triglyceride fraction derived from [U- 14 C] isoleucine also contained esterified C15, C13, C11, C9, C7 and possibly shorter anteiso-branched acids

  18. Texture of lipid bilayer domains

    DEFF Research Database (Denmark)

    Jensen, Uffe Bernchou; Brewer, Jonathan R.; Midtiby, Henrik Skov

    2009-01-01

    We investigate the texture of gel (g) domains in binary lipid membranes composed of the phospholipids DPPC and DOPC. Lateral organization of lipid bilayer membranes is a topic of fundamental and biological importance. Whereas questions related to size and composition of fluid membrane domain...... are well studied, the possibility of texture in gel domains has so far not been examined. When using polarized light for two-photon excitation of the fluorescent lipid probe Laurdan, the emission intensity is highly sensitive to the angle between the polarization and the tilt orientation of lipid acyl...... chains. By imaging the intensity variations as a function of the polarization angle, we map the lateral variations of the lipid tilt within domains. Results reveal that gel domains are composed of subdomains with different lipid tilt directions. We have applied a Fourier decomposition method...

  19. In vitro digestion of curcuminoid-loaded lipid nanoparticles

    International Nuclear Information System (INIS)

    Noack, Andreas; Oidtmann, Johannes; Kutza, Johannes; Mäder, Karsten

    2012-01-01

    Curcuminoid-loaded lipid nanoparticles were produced by melt homogenization. The used lipid matrices were medium chain triglycerides, trimyristin (TM), and tristearin. The mean particle size of the preparations was between 130 and 180 nm. The incorporated curcuminoids revealed a good stability over a period of 12 months. The curcuminoid-loaded lipid nanoparticles were intended for the oral delivery of curcuminoids. Therefore, the fate of the triglyceride matrix in simulated gastric and simulated intestinal media under the influence of pepsin and pancreatin, respectively, was assessed. The degradation of the triglycerides was monitored by the pH–stat method and with high performance thin layer chromatography in connection with spectrodensitometry to quantify the different lipid fractions. The TM nanoparticles were not degraded in simulated gastric fluid (SGF), but the decomposition of the triglyceride matrix was rapid in the intestinal media. The digestion process was faster in the simulated fed state medium compared to the simulated fasted state medium. Additionally, the stability of the incorporated drug was tested in the respective physiological media. The curcuminoids showed an overall good stability in the different test media. The release of the curcuminoids from the lipid nanoparticles was determined by fluorescence imaging techniques. A slow release of the drug was found in phosphate buffer. In contrast, a more distinct release of the curcuminoids was verifiable in SGF and in simulated intestinal fluids. Overall, it was considered that the transfer of the drug into the outer media was mainly triggered by the lipid degradation and not by drug release.

  20. Lipids and membrane lateral organization

    Directory of Open Access Journals (Sweden)

    Sandro eSonnino

    2010-11-01

    Full Text Available Shortly after the elucidation of the very basic structure and properties of cellular membranes, it became evident that cellular membranes are highly organized structures with multiple and multi-dimensional levels of order. Very early observations suggested that the lipid components of biological membranes might be active players in the creations of these levels of order. In the late 80’s, several different and diverse experimental pieces of evidence coalesced together giving rise to the lipid raft hypothesis. Lipid rafts became enormously (and, in the opinion of these authors, sometimes acritically popular, surprisingly not just within the lipidologist community (who is supposed to be naturally sensitive to the fascination of lipid rafts. Today, a PubMed search using the key word lipid rafts returned a list of 3767 papers, including 690 reviews (as a term of comparison, searching over the same time span for a very hot lipid-related key word, ceramide returned 6187 hits with 799 reviews, and a tremendous number of different cellular functions have been described as lipid raft-dependent. However, a clear consensus definition of lipid raft has been proposed only in recent times, and the basic properties, the ruling forces, and even the existence of lipid rafts in living cells have been recently matter of intense debate. The scenario that is gradually emerging from the controversies elicited by the lipid raft hypothesis emphasize multiple roles for membrane lipids in determining membrane order, that encompasses their tendency to phase separation but are clearly not limited to this. In this review, we would like to re-focus the attention of the readers on the importance of lipids in organizing the fine structure of cellular membranes.

  1. Symbiodinium genotypic and environmental controls on lipids in reef building corals.

    Directory of Open Access Journals (Sweden)

    Timothy F Cooper

    Full Text Available BACKGROUND: Lipids in reef building corals can be divided into two classes; non-polar storage lipids, e.g. wax esters and triglycerides, and polar structural lipids, e.g. phospholipids and cholesterol. Differences among algal endosymbiont types are known to have important influences on processes including growth and the photobiology of scleractinian corals yet very little is known about the role of symbiont types on lipid energy reserves. METHODOLOGY/PRINCIPAL FINDINGS: The ratio of storage lipid and structural lipid fractions of Scott Reef corals were determined by thin layer chromatography. The lipid fraction ratio varied with depth and depended on symbiont type harboured by two corals (Seriatopora hystrix and Pachyseris speciosa. S. hystrix colonies associated with Symbiodinium C1 or C1/C# at deep depths (>23 m had lower lipid fraction ratios (i.e. approximately equal parts of storage and structural lipids than those with Symbiodinium D1 in shallow depths (<23 m, which had higher lipid fraction ratios (i.e. approximately double amounts of storage relative to structural lipid. Further, there was a non-linear relationship between the lipid fraction ratio and depth for S. hystrix with a modal peak at ∼23 m coinciding with the same depth as the shift from clade D to C types. In contrast, the proportional relationship between the lipid fraction ratio and depth for P. speciosa, which exhibited high specificity for Symbiodinium C3 like across the depth gradient, was indicative of greater amounts of storage lipids contained in the deep colonies. CONCLUSIONS/SIGNIFICANCE: This study has demonstrated that Symbiodinium exert significant controls over the quality of coral energy reserves over a large-scale depth gradient. We conclude that the competitive advantages and metabolic costs that arise from flexible associations with divergent symbiont types are offset by energetic trade-offs for the coral host.

  2. Unraveling lipid metabolism in lipid-dependent pathogenic Malassezia yeasts

    NARCIS (Netherlands)

    Celis Ramirez, A.M.

    2017-01-01

    Malassezia yeasts are lipid-dependent fungal species that are common members of the human and animal skin microbiota. The lipid-dependency is a crucial trait in the adaptation process to grow on the skin but also plays a role in their pathogenic life style. Malassezia species can cause several skin

  3. Update of the LIPID MAPS comprehensive classification system for lipids

    NARCIS (Netherlands)

    Fahy, E.; Subramaniam, S.; Murphy, R.C.; Nishijima, M.; Raetz, C.R.H.; Shimizu, T.; Spener, F.; van Meer, G.|info:eu-repo/dai/nl/068570368; Wakelam, M.J.O.; Dennis, E.A.

    2009-01-01

    In 2005, the International Lipid Classification and Nomenclature Committee under the sponsorship of the LIPID MAPS Consortium developed and established a “Comprehensive Classification System for Lipids” based on well-defined chemical and biochemical principles and using an ontology that is

  4. Cell-based lipid flippase assay employing fluorescent lipid derivatives

    DEFF Research Database (Denmark)

    Jensen, Maria Stumph; Costa, Sara; Günther-Pomorski, Thomas

    2016-01-01

    P-type ATPases in the P4 subfamily (P4-ATPases) are transmembrane proteins unique for eukaryotes that act as lipid flippases, i.e., to translocate phospholipids from the exofacial to the cytofacial monolayer of cellular membranes. While initially characterized as aminophospholipid translocases, s...... flippase activities in the plasma membrane of cells, using yeast as an example.......P-type ATPases in the P4 subfamily (P4-ATPases) are transmembrane proteins unique for eukaryotes that act as lipid flippases, i.e., to translocate phospholipids from the exofacial to the cytofacial monolayer of cellular membranes. While initially characterized as aminophospholipid translocases......, studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates. Here, we describe an assay based on fluorescent lipid derivatives to monitor and characterize lipid...

  5. Surface analysis of lipids by mass spectrometry: more than just imaging.

    Science.gov (United States)

    Ellis, Shane R; Brown, Simon H; In Het Panhuis, Marc; Blanksby, Stephen J; Mitchell, Todd W

    2013-10-01

    Mass spectrometry is now an indispensable tool for lipid analysis and is arguably the driving force in the renaissance of lipid research. In its various forms, mass spectrometry is uniquely capable of resolving the extensive compositional and structural diversity of lipids in biological systems. Furthermore, it provides the ability to accurately quantify molecular-level changes in lipid populations associated with changes in metabolism and environment; bringing lipid science to the "omics" age. The recent explosion of mass spectrometry-based surface analysis techniques is fuelling further expansion of the lipidomics field. This is evidenced by the numerous papers published on the subject of mass spectrometric imaging of lipids in recent years. While imaging mass spectrometry provides new and exciting possibilities, it is but one of the many opportunities direct surface analysis offers the lipid researcher. In this review we describe the current state-of-the-art in the direct surface analysis of lipids with a focus on tissue sections, intact cells and thin-layer chromatography substrates. The suitability of these different approaches towards analysis of the major lipid classes along with their current and potential applications in the field of lipid analysis are evaluated. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Solid lipid nanoparticles for parenteral drug delivery

    NARCIS (Netherlands)

    Wissing, S.A.; Kayser, Oliver; Muller, R.H.

    2004-01-01

    This review describes the use of nanoparticles based on solid lipids for the parenteral application of drugs. Firstly, different types of nanoparticles based on solid lipids such as "solid lipid nanoparticles" (SLN), "nanostructured lipid carriers" (NLC) and "lipid drug conjugate" (LDC)

  7. Analysis of lipid profile in lipid storage myopathy.

    Science.gov (United States)

    Aguennouz, M'hammed; Beccaria, Marco; Purcaro, Giorgia; Oteri, Marianna; Micalizzi, Giuseppe; Musumesci, Olimpia; Ciranni, Annmaria; Di Giorgio, Rosa Maria; Toscano, Antonio; Dugo, Paola; Mondello, Luigi

    2016-09-01

    Lipid dysmetabolism disease is a condition in which lipids are stored abnormally in organs and tissues throughout the body, causing muscle weakness (myopathy). Usually, the diagnosis of this disease and its characterization goes through dosage of Acyl CoA in plasma accompanied with evidence of droplets of intra-fibrils lipids in the patient muscle biopsy. However, to understand the pathophysiological mechanisms of lipid storage diseases, it is useful to identify the nature of lipids deposited in muscle fiber. In this work fatty acids and triglycerides profile of lipid accumulated in the muscle of people suffering from myopathies syndromes was characterized. In particular, the analyses were carried out on the muscle biopsy of people afflicted by lipid storage myopathy, such as multiple acyl-coenzyme A dehydrogenase deficiency, and neutral lipid storage disease with myopathy, and by the intramitochondrial lipid storage dysfunctions, such as deficiencies of carnitine palmitoyltransferase II enzyme. A single step extraction and derivatization procedure was applied to analyze fatty acids from muscle tissues by gas chromatography with a flame ionization detector and with an electronic impact mass spectrometer. Triglycerides, extracted by using n-hexane, were analyzed by high performance liquid chromatography coupled to mass spectrometer equipped with an atmospheric pressure chemical ionization interface. The most representative fatty acids in all samples were: C16:0 in the 13-24% range, C18:1n9 in the 20-52% range, and C18:2n6 in the 10-25% range. These fatty acids were part of the most representative triglycerides in all samples. The data obtained was statistically elaborated performing a principal component analysis. A satisfactory discrimination was obtained among the different diseases. Using component 1 vs component 3 a 43.3% of total variance was explained. Such results suggest the important role that lipid profile characterization can have in supporting a correct

  8. The Flexibility of Ectopic Lipids

    Directory of Open Access Journals (Sweden)

    Hannah Loher

    2016-09-01

    Full Text Available In addition to the subcutaneous and the visceral fat tissue, lipids can also be stored in non-adipose tissue such as in hepatocytes (intrahepatocellular lipids; IHCL, skeletal (intramyocellular lipids; IMCL or cardiac muscle cells (intracardiomyocellular lipids; ICCL. Ectopic lipids are flexible fuel stores that can be depleted by physical exercise and repleted by diet. They are related to obesity and insulin resistance. Quantification of IMCL was initially performed invasively, using muscle biopsies with biochemical and/or histological analysis. 1H-magnetic resonance spectroscopy (1H-MRS is now a validated method that allows for not only quantifying IMCL non-invasively and repeatedly, but also assessing IHCL and ICCL. This review summarizes the current available knowledge on the flexibility of ectopic lipids. The available evidence suggests a complex interplay between quantitative and qualitative diet, fat availability (fat mass, insulin action, and physical exercise, all important factors that influence the flexibility of ectopic lipids. Furthermore, the time frame of the intervention on these parameters (short-term vs. long-term appears to be critical. Consequently, standardization of physical activity and diet are critical when assessing ectopic lipids in predefined clinical situations.

  9. Neuroimaging of Lipid Storage Disorders

    Science.gov (United States)

    Rieger, Deborah; Auerbach, Sarah; Robinson, Paul; Gropman, Andrea

    2013-01-01

    Lipid storage diseases, also known as the lipidoses, are a group of inherited metabolic disorders in which there is lipid accumulation in various cell types, including the central nervous system, because of the deficiency of a variety of enzymes. Over time, excessive storage can cause permanent cellular and tissue damage. The brain is particularly…

  10. Fasting and nonfasting lipid levels

    DEFF Research Database (Denmark)

    Langsted, Anne; Freiberg, Jacob J; Nordestgaard, Børge G

    2008-01-01

    Lipid profiles are usually measured after fasting. We tested the hypotheses that these levels change only minimally in response to normal food intake and that nonfasting levels predict cardiovascular events.......Lipid profiles are usually measured after fasting. We tested the hypotheses that these levels change only minimally in response to normal food intake and that nonfasting levels predict cardiovascular events....

  11. Lipid and bile acid analysis

    NARCIS (Netherlands)

    Argmann, Carmen A.; Houten, Sander M.; Champy, Marie-France; Auwerx, Johan

    2006-01-01

    Lipids are important body constituents that are vital for cellular, tissue, and whole-body homeostasis. Lipids serve as crucial membrane components, constitute the body's main energy reservoir, and are important signaling molecules. As a consequence of these pleiotropic functions, many common

  12. Understanding crumpling lipid vesicles at the gel phase transition

    Science.gov (United States)

    Hirst, Linda; Ossowski, Adam; Fraser, Matthew

    2011-03-01

    Wrinkling and crumpling transitions in different membrane types have been studied extensively in recent years both theoretically and computationally. There has also been very interesting recent work on defects in liquid crystalline shells. Lipid bilayer vesicles, widely used in biophysical research can be considered as a single layer smectic shell in the liquid crystalline phase. On cooling the lipid vesicle a transition to the gel phase may take place in which the lipid chains tilt and assume a more ordered packing arrangement. We observe large scale morphological changes in vesicles close to this transition point using fluorescence microscopy and investigate the possible mechanisms for this transition. Confocal microscopy is used to map 3D vesicle shape and crumpling length-scales. We also employ the molecular tilt sensitive dye, Laurdan to investigate the role of tilt domain formation on macroscopic structure. Funded by NSF CAREER award (DMR - BMAT #0852791).

  13. Evidence Suggesting That Francisella tularensis O-Antigen Capsule Contains a Lipid A-Like Molecule That Is Structurally Distinct from the More Abundant Free Lipid A.

    Directory of Open Access Journals (Sweden)

    Jason H Barker

    Full Text Available Francisella tularensis, the Gram-negative bacterium that causes tularemia, produces a high molecular weight capsule that is immunologically distinct from Francisella lipopolysaccharide but contains the same O-antigen tetrasaccharide. To pursue the possibility that the capsule of Francisella live vaccine strain (LVS has a structurally unique lipid anchor, we have metabolically labeled Francisella with [14C]acetate to facilitate highly sensitive compositional analysis of capsule-associated lipids. Capsule was purified by two independent methods and yielded similar results. Autoradiographic and immunologic analysis confirmed that this purified material was largely devoid of low molecular weight LPS and of the copious amounts of free lipid A that the Francisellae accumulate. Chemical hydrolysis yielded [14C]-labeled free fatty acids characteristic of Francisella lipid A but with a different molar ratio of 3-OH C18:0 to 3-OH C16:0 and different composition of non-hydroxylated fatty acids (mainly C14:0 rather than C16:0 than that of free Francisella lipid A. Mild acid hydrolysis to induce selective cleavage of KDO-lipid A linkage yielded a [14C]-labeled product that partitioned during Bligh/Dyer extraction and migrated during thin-layer chromatography like lipid A. These findings suggest that the O-antigen capsule of Francisella contains a covalently linked and structurally distinct lipid A species. The presence of a discrete lipid A-like molecule associated with capsule raises the possibility that Francisella selectively exploits lipid A structural heterogeneity to regulate synthesis, transport, and stable bacterial surface association of the O-antigen capsular layer.

  14. Lysosomal degradation of membrane lipids.

    Science.gov (United States)

    Kolter, Thomas; Sandhoff, Konrad

    2010-05-03

    The constitutive degradation of membrane components takes place in the acidic compartments of a cell, the endosomes and lysosomes. Sites of lipid degradation are intralysosomal membranes that are formed in endosomes, where the lipid composition is adjusted for degradation. Cholesterol is sorted out of the inner membranes, their content in bis(monoacylglycero)phosphate increases, and, most likely, sphingomyelin is degraded to ceramide. Together with endosomal and lysosomal lipid-binding proteins, the Niemann-Pick disease, type C2-protein, the GM2-activator, and the saposins sap-A, -B, -C, and -D, a suitable membrane lipid composition is required for degradation of complex lipids by hydrolytic enzymes. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  15. Lipid composition of the stratum corneum and cutaneous water loss in birds along an aridity gradient.

    Science.gov (United States)

    Champagne, Alex M; Muñoz-Garcia, Agustí; Shtayyeh, Tamer; Tieleman, B Irene; Hegemann, Arne; Clement, Michelle E; Williams, Joseph B

    2012-12-15

    Intercellular and covalently bound lipids within the stratum corneum (SC), the outermost layer of the epidermis, are the primary barrier to cutaneous water loss (CWL) in birds. We compared CWL and intercellular SC lipid composition in 20 species of birds from desert and mesic environments. Furthermore, we compared covalently bound lipids with CWL and intercellular lipids in the lark family (Alaudidae). We found that CWL increases in birds from more mesic environments, and this increase was related to changes in intercellular SC lipid composition. The most consistent pattern that emerged was a decrease in the relative amount of cerebrosides as CWL increased, a pattern that is counterintuitive based on studies of mammals with Gaucher disease. Although covalently bound lipids in larks did not correlate with CWL, we found that covalently bound cerebrosides correlated positively with intercellular cerebrosides and intercellular cholesterol ester, and intercellular cerebrosides correlated positively with covalently bound free fatty acids. Our results led us to propose a new model for the organization of lipids in the avian SC, in which the sugar moieties of cerebrosides lie outside of intercellular lipid layers, where they may interdigitate with adjacent intercellular cerebrosides or with covalently bound cerebrosides.

  16. Multi-Stacked Supported Lipid Bilayer Micropatterning through Polymer Stencil Lift-Off

    Directory of Open Access Journals (Sweden)

    Yujie Zhu

    2015-08-01

    Full Text Available Complex multi-lamellar structures play a critical role in biological systems, where they are present as lamellar bodies, and as part of biological assemblies that control energy transduction processes. Multi-lamellar lipid layers not only provide interesting systems for fundamental research on membrane structure and bilayer-associated polypeptides, but can also serve as components in bioinspired materials or devices. Although the ability to pattern stacked lipid bilayers at the micron scale is of importance for these purposes, limited work has been done in developing such patterning techniques. Here, we present a simple and direct approach to pattern stacked supported lipid bilayers (SLBs using polymer stencil lift-off and the electrostatic interactions between cationic and anionic lipids. Both homogeneous and phase-segregated stacked SLB patterns were produced, demonstrating that the stacked lipid bilayers retain lateral diffusivity. We demonstrate patterned SLB stacks of up to four bilayers, where fluorescence resonance energy transfer (FRET and quenching was used to probe the interactions between lipid bilayers. Furthermore, the study of lipid phase behaviour showed that gel phase domains align between adjacent layers. The proposed stacked SLB pattern platform provides a robust model for studying lipid behaviour with a controlled number of bilayers, and an attractive means towards building functional bioinspired materials or devices.

  17. Lipid profiling in sewage sludge.

    Science.gov (United States)

    Zhu, Fenfen; Wu, Xuemin; Zhao, Luyao; Liu, Xiaohui; Qi, Juanjuan; Wang, Xueying; Wang, Jiawei

    2017-06-01

    High value-added reutilization of sewage sludge from wastewater treatment plants (WWTPs) is essential in sustainable development in WWTPs. However, despite the advantage of high value reutilization, this process must be based on a detailed study of organics in sludge. We used the methods employed in life sciences to determine the profile of lipids (cellular lipids, free fatty acids (FFAs), and wax/gum) in five sludge samples obtained from three typical WWTPs in Beijing; these samples include one sludge sample from a primary sedimentation tank, two activated sludge samples from two Anaerobic-Anoxic-Oxic (A2/O) tanks, and two activated sludge samples from two membrane bioreactor tanks. The percentage of total raw lipids varied from 2.90% to 12.3%. Sludge from the primary sedimentation tank showed the highest concentrations of lipid, FFA, and wax/gum and the second highest concentration of cellular lipids. All activated sludge contained an abundance of cellular lipids (>54%). Cells in sludge can from plants, animals, microbes and so on in wastewater. Approximately 14 species of cellular lipids were identified, including considerable high value-potential ceramide (9567-38774 mg/kg), coenzyme (937-3897 mg/kg), and some phosphatidylcholine (75-548 mg/kg). The presence of those lipid constituents would thus require a wider range of recovery methods for sludge. Both cellular lipids and FFAs contain an abundance of C16-C18 lipids at high saturation level, and they serve as good resources for biodiesel production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Inter-and intra-individual differences in skin hydration and surface lipids measured with mid-infrared spectroscopy

    NARCIS (Netherlands)

    Ezerskaia, A.; Pereira, S.F.; Urbach, Paul; Varghese, Babu; Coté, Gerard L.

    2016-01-01

    Skin health is characterized by heterogeneous system of water and lipids in upper layers providing protection from external environment and preventing loss of vital components of the body. Skin hydration (moisture) and sebum (skin surface lipids) are considered to be important factors in skin

  19. Parvovirus B19 VLP recognizes globoside in supported lipid bilayers.

    Science.gov (United States)

    Nasir, Waqas; Nilsson, Jonas; Olofsson, Sigvard; Bally, Marta; Rydell, Gustaf E

    2014-05-01

    Studies have suggested that the glycosphingolipid globoside (Gb4Cer) is a receptor for human parvovirus B19. Virus-like particles bind to Gb4Cer on thin-layer chromatograms, but a direct interaction between the virus and lipid membrane-associated Gb4Cer has been debated. Here, we characterized the binding of parvovirus B19 VP1/VP2 virus-like particles to glycosphingolipids (i) on thin-layer chromatograms (TLCs) and (ii) incorporated into supported lipid bilayers (SLBs) acting as cell-membrane mimics. The binding specificities of parvovirus B19 determined in the two systems were in good agreement; the VLP recognized both Gb4Cer and the Forssman glycosphingolipid on TLCs and in SLBs compatible with the role of Gb4Cer as a receptor for this virus. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Coral lipids and environmental stress.

    Science.gov (United States)

    Harriott, V J

    1993-04-01

    Environmental monitoring of coral reefs is presently limited by difficulties in recognising coral stress, other than by monitoring coral mortality over time. A recent report described an experiment demonstrating that a measured lipid index declined in shaded corals. The technique described might have application in monitoring coral health, with a decline in coral lipid index as an indicator of coral stress. The application of the technique as a practical monitoring tool was tested for two coral species from the Great Barrier Reef. Consistent with the previous results, lipid index for Pocillopora damicornis initially declined over a period of three weeks in corals maintained in filtered seawater in the dark, indicating possible utilization of lipid stored as energy reserves. However, lipid index subsequently rose to near normal levels. In contrast, lipid index of Acropora formosa increased after four weeks in the dark in filtered seawater. The results showed considerable variability in lipid content between samples from the same colony. Results were also found to be dependent on fixation times and sample weight, introducing potential error into the practical application of the technique. The method as described would be unsuitable for monitoring environmental stress in corals, but the search for a practical method to monitor coral health should continue, given its importance in coral reef management.

  1. Ocular surface disease incidence in patients with open-angle glaucoma

    Directory of Open Access Journals (Sweden)

    Radenković Marija

    2016-01-01

    Full Text Available Introduction. Ocular surface disease (OSD is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbances, tear film instability with potential damage to the ocular surface, accompanied by increased tear film osmolarity and inflammation of the ocular surface. It is a consequence of disrupted homeostasis of lacrimal functional unit. The main pathogenetic mechanism stems from tear hyperosmolarity and tear film instability. The etiological classification is hyposecretory (Sy-Sjögren and non-Sjögren and evaporative (extrinsic and intrinsic form. Delphi panel classification grades disease stages. Antiglaucoma topical therapy causes exacerbation or occurrence of symptoms of dry eye due to main ingredients or preservatives (benzalkonium chloride - BAK, which are dose- and time-dependent. BAK reduces the stability of the lipid layer of tears, the number of goblet cells, induces apoptosis and inflammatory infiltration. Objective. The aim of this study was the analysis of the OSD incidence in open-angle glaucoma patients caused by topical medicamentous therapy. Methods. Retrospective analysis of examined patients with open-angle glaucoma was used. Results. Increased incidence of moderate and advanced OSD Index degrees in the group of primary open-angle glaucoma (POAG and pseudoexfoliative glaucoma. According to the Delphi Panel Scale the most common grade is IIb (POAG and pseudoexfoliative glaucoma. Evaporative form of OSD prevailed in all treatment groups. High percentage of dry eye in patients with higher concentrations of preservatives applied was noticed. Conclusion. OSD should be timely diagnosed and treated. Dry eye has an impact on surgical outcome and postoperative visual acuity, and in order to improve patient compliance and quality of life, symptoms of dry eye should be addressed and medications with lower concentrations of preservatives should be applied.

  2. Ocular surface disease incidence in patients with open-angle glaucoma.

    Science.gov (United States)

    Radenković, Marija; Stanković-Babić, Gordana; Jovanović, Predrag; Djordjević-Jocić, Jasmina; Trenkić-Božinović, Marija

    2016-01-01

    Ocular surface disease (OSD) is a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbances, tear film instability with potential damage to the ocular surface, accompanied by increased tear film osmolarity and inflammation of the ocular surface. It is a consequence of disrupted homeostasis of lacrimal functional unit. The main pathogenetic mechanism stems from tear hyperosmolarity and tear film instability. The etiological classification is hyposecretory (Sy-Sjögren and non-Sjögren) and evaporative (extrinsic and intrinsic) form. Delphi panel classification grades disease stages. Antiglaucoma topical therapy causes exacerbation or occurrence of symptoms of dry eye due to main ingredients or preservatives (benzalkonium chloride – BAK), which are dose- and time-dependent. BAK reduces the stability of the lipid layer of tears, the number of goblet cells, induces apoptosis and inflammatory infiltration. The aim of this study was the analysis of the OSD incidence in open-angle glaucoma patients caused by topical medicamentous therapy. Retrospective analysis of examined patients with open-angle glaucoma was used. Increased incidence of moderate and advanced OSD Index degrees in the group of primary open-angle glaucoma (POAG) and pseudoexfoliative glaucoma. According to the Delphi Panel Scale the most common grade is IIb (POAG and pseudoexfoliative glaucoma). Evaporative form of OSD prevailed in all treatment groups. High percentage of dry eye in patients with higher concentrations of preservatives applied was noticed. OSD should be timely diagnosed and treated. Dry eye has an impact on surgical outcome and postoperative visual acuity, and in order to improve patient compliance and quality of life, symptoms of dry eye should be addressed and medications with lower concentrations of preservatives should be applied.

  3. Thermodynamics of interaction of ionic liquids with lipid monolayer.

    Science.gov (United States)

    Bhattacharya, G; Mitra, S; Mandal, P; Dutta, S; Giri, R P; Ghosh, S K

    2018-06-01

    Understanding the interaction of ionic liquids with cellular membrane becomes utterly important to comprehend the activities of these liquids in living organisms. Lipid monolayer formed at the air-water interface is employed as a model system to follow this interaction by investigating important thermodynamic parameters. The penetration kinetics of the imidazolium-based ionic liquid 1-decyl-3-methylimidazolium tetrafluoroborate ([DMIM][BF4]) into the zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid layer is found to follow the Boltzmann-like equation that reveals the characteristic time constant which is observed to be the function of initial surface pressure. The enthalpy and entropy calculated from temperature-dependent pressure-area isotherms of the monolayer show that the added ionic liquids bring about a disordering effect in the lipid film. The change in Gibbs free energy indicates that an ionic liquid with longer chain has a far greater disordering effect compared to an ionic liquid with shorter chain. The differential scanning calorimetric measurement on a multilamellar vesicle system shows the main phase transition temperature to shift to a lower value, which, again, indicates the disordering effect of the ionic liquid on lipid membrane. All these studies fundamentally point out that, when ionic liquids interact with lipid molecules, the self-assembled structure of a cellular membrane gets perturbed, which may be the mechanism of these molecules having adverse effects on living organisms.

  4. Bovine and human insulin adsorption at lipid monolayers: a comparison

    Science.gov (United States)

    Mauri, Sergio; Pandey, Ravindra; Rzeznicka, Izabela; Lu, Hao; Bonn, Mischa; Weidner, Tobias

    2015-07-01

    Insulin is a widely used peptide in protein research and it is utilised as a model peptide to understand the mechanics of fibril formation, which is believed to be the cause of diseases such as Alzheimer and Creutzfeld-Jakob syndrome. Insulin has been used as a model system due to its biomedical relevance, small size and relatively simple tertiary structure. The adsorption of insu lin on a variety of surfaces has become the focus of numerous studies lately. These works have helped in elucidating the consequence of surface/protein hydrophilic/hydrophobic interaction in terms of protein refolding and aggregation. Unfortunately, such model surfaces differ significantly from physiological surfaces. Here we spectroscopically investigate the adsorption of insulin at lipid monolayers, to further our understanding of the interaction of insulin with biological surfaces. In particular we study the effect of minor mutations of insulin’s primary amino acid sequence on its interaction with 1,2-Dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) model lipid layers. We probe the structure of bovine and human insulin at the lipid/water interface using sum frequency generation spectroscopy (SFG). The SFG experiments are complemented with XPS analysis of Langmuir-Schaefer deposited lipid/insulin films. We find that bovine and human insulin, even though very similar in sequence, show a substantially different behavior when interacting with lipid films.

  5. Molecular dynamics study of structure and vibrational spectra at zwitterionoic lipid/aqueous KCl, NaCl, and CaCl2 solution interfaces

    Science.gov (United States)

    Ishiyama, Tatsuya; Shirai, Shinnosuke; Okumura, Tomoaki; Morita, Akihiro

    2018-06-01

    Molecular dynamics (MD) simulations of KCl, NaCl, and CaCl2 solution/dipalmytoylphosphatidylcholine lipid interfaces were performed to analyze heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectra in relation to the interfacial water structure. The present MD simulation well reproduces the experimental spectra and elucidates a specific cation effect on the interfacial structure. The K+, Na+, and Ca2+ cation species penetrate in the lipid layer more than the anions in this order, due to the electrostatic interaction with negative polar groups of lipid, and the electric double layer between the cations and anions cancels the intrinsic orientation of water at the water/lipid interface. These mechanisms explain the HD-VSFG spectrum of the water/lipid interface and its spectral perturbation by adding the ions. The lipid monolayer reverses the order of surface preference of the cations at the solution/lipid interface from that at the solution/air interface.

  6. Lipid metabolism in cancer cachexia.

    OpenAIRE

    Mulligan, H. D.; Beck, S. A.; Tisdale, M. J.

    1992-01-01

    The effect of cancer cachexia on the oxidative metabolism of lipids has been studied in mice transplanted either with the MAC16 adenocarcinoma, which induces profound loss of body weight and depletion of lipid stores, or the MAC13 adenocarcinoma, which is the same histological type, but which grows without an effect on host body weight or lipid stores. While oxidation of D-[U-14C]glucose did not differ between animals bearing tumours of either type and non-tumour bearing controls, oxidation o...

  7. Adjusting membrane lipids under salt stress: the case of the moderate halophilic organism Halobacillus halophilus.

    Science.gov (United States)

    Lopalco, Patrizia; Angelini, Roberto; Lobasso, Simona; Köcher, Saskia; Thompson, Melanie; Müller, Volker; Corcelli, Angela

    2013-04-01

    The lipid composition of Halobacillus halophilus was investigated by combined thin-layer chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses of the total lipid extract. Main polar lipids were found to be sulfoquinovosyldiacylglycerol and phosphatidylglycerol, while cardiolipin was a minor lipid together with phosphatidic acid, alanyl-phosphatidylglycerol and two not yet fully identified lipid components. In addition the analyses of residual lipids, associated with denatured proteins after the lipid extraction, revealed the presence of significant amounts of cardiolipin, indicating that it is a not readily extractable phospholipid. Post decay source mass spectrometry analyses allowed the determination of acyl chains of main lipid components. On increasing the culture medium salinity, an increase in the shorter chains and the presence of chain unsaturations were observed. These changes in the lipid core structures might compensate for the increase in packing and rigidity of phospholipid and sulfoglycolipid polar heads in high-salt medium, therefore contributing to the homeostasis of membrane fluidity and permeability in salt stress conditions. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  8. Muscle Lipid Metabolism: Role of Lipid Droplets and Perilipins

    Directory of Open Access Journals (Sweden)

    Pablo Esteban Morales

    2017-01-01

    Full Text Available Skeletal muscle is one of the main regulators of carbohydrate and lipid metabolism in our organism, and therefore, it is highly susceptible to changes in glucose and fatty acid (FA availability. Skeletal muscle is an extremely complex tissue: its metabolic capacity depends on the type of fibers it is made up of and the level of stimulation it undergoes, such as acute or chronic contraction. Obesity is often associated with increased FA levels, which leads to the accumulation of toxic lipid intermediates, oxidative stress, and autophagy in skeletal fibers. This lipotoxicity is one of the most common causes of insulin resistance (IR. In this scenario, the “isolation” of certain lipids in specific cell compartments, through the action of the specific lipid droplet, perilipin (PLIN family of proteins, is conceived as a lifeguard compensatory strategy. In this review, we summarize the cellular mechanism underlying lipid mobilization and metabolism inside skeletal muscle, focusing on the function of lipid droplets, the PLIN family of proteins, and how these entities are modified in exercise, obesity, and IR conditions.

  9. The impact of resveratrol in lipid bilayers

    DEFF Research Database (Denmark)

    Shen, Chen; de Ghellinck, Alexis; Fragneto, Giovanna

    The natural antioxidant resveratrol, contained in the skin of red grape and accordingly in their wines, is hold liable for health impacts such as cardiovascular protection and anti-oxidative effect. Clinical trials of resveratrol as prophylactic or even therapeutic drug are ongoing. However, basic...... knowledge on its probable working mechanism is rare. In this biophysical study, neutron reflectometry was used to investigate the direct impact of resveratrol on lipid membranes with solid supported bilayers. When interacting with di- palmitoyl-phosphatidyl-choline (DPPC) bilayers, resveratrol accumulates...... in between the headgroups but is absent in the hydrophobic core. Without a biogenic removal mechanism, the headgroup region may host up to ~25 mol% of resveratrol. The average thickness and the interfacial roughness of the headgroup layer are increased. From the structural results, the average tilting...

  10. Blood lipids and prostate cancer

    DEFF Research Database (Denmark)

    Bull, Caroline J; Bonilla, Carolina; Holly, Jeff M P

    2016-01-01

    Genetic risk scores were used as unconfounded instruments for specific lipid traits (Mendelian randomization) to assess whether circulating lipids causally influence prostate cancer risk. Data from 22,249 prostate cancer cases and 22,133 controls from 22 studies within the international PRACTICAL...... into logistic regression models to estimate the presence (and direction) of any causal effect of each lipid trait on prostate cancer risk. There was weak evidence for an association between the LDL genetic score and cancer grade: the odds ratio (OR) per genetically instrumented standard deviation (SD) in LDL.......95, 3.00; P = 0.08). The rs12916-T variant in 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) was inversely associated with prostate cancer (OR: 0.97; 95% CI: 0.94, 1.00; P = 0.03). In conclusion, circulating lipids, instrumented by our genetic risk scores, did not appear to alter prostate cancer risk...

  11. Lipids of the ultra-thin square halophilic archaeon Haloquadratum walsbyi

    Directory of Open Access Journals (Sweden)

    Simona LoBasso

    2008-01-01

    Full Text Available The lipid composition of the extremely halophilic archaeon Haloquadratum walsbyi was investigated by thin-layer chromatography and electrospray ionization-mass spectrometry. The analysis of neutral lipids showed the presence of vitamin MK-8, squalene, carotene, bacterioruberin and several retinal isomers. The major polar lipids were phosphatidylglycerophosphate methyl ester, phosphatidylglycerosulfate, phosphatidylglycerol and sulfated diglycosyl diether lipid. Among cardiolipins, the tetra-phytanyl or dimeric phospholipids, only traces of bisphosphatidylglycerol were detected. When the cells were exposed to hypotonic medium, no changes in the membrane lipid composition occurred. Distinguishing it from other extreme halophiles of the Halobacteriaceae family, the osmotic stress did not induce the neo-synthesis of cardiolipins in H. walsbyi. The difference may depend on the three-laminar structure of the cell wall, which differs significantly from that of other Haloarchaea.

  12. Protein aggregation in food models: effect of γ-irradiation and lipid oxidation

    International Nuclear Information System (INIS)

    Delincee, H.; Paul, P.

    1981-01-01

    Myoglobin and serum albumin have been irradiated in aqueous solution in the presence of varying amounts of carbohydrates and lipids, and the yield of protein aggregates has been determined by gel filtration. With myoglobin the formation of aggregates evolving from the reaction with oxidizing lipids was observed, which was not found for serum albumin. The production of protein-lipid complexes, in which lipid material was occluded in the high-molecular aggregates by physical forces was demonstrated. Gel filtration and gel electrophoresis, both in the presence of SDS, and thin-layer isoelectric focusing revealed distinct structural differenes between the protein aggregates induced by irradiation and the aggregates formed by interaction with oxidizing lipids

  13. Bioactive Lipids in Dairy Fat

    DEFF Research Database (Denmark)

    Hellgren, Lars; Nordby, Pernille

    2017-01-01

    Milk fat is the most important energy source for the newborn infant beside its important role as energy source, milk fat also contain a range of bioactive lipids, that potentially can modulate the immune response and metabolic regulation in the child. In this chapter we review the literature on b...... on bioactive dairy fatty acids: conjugated linoleic acid, branched chained and odd chained fatty acids, as well as bioactive complex lipids such as sphingomyelin and gangliosides....

  14. Reassembly of S-layer proteins

    International Nuclear Information System (INIS)

    Pum, Dietmar; Sleytr, Uwe B

    2014-01-01

    Crystalline bacterial cell surface layers (S-layers) represent the outermost cell envelope component in a broad range of bacteria and archaea. They are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. They are highly porous protein mesh works with unit cell sizes in the range of 3 to 30 nm, and pore sizes of 2 to 8 nm. S-layers are usually 5 to 20 nm thick (in archaea, up to 70 nm). S-layer proteins are one of the most abundant biopolymers on earth. One of their key features, and the focus of this review, is the intrinsic capability of isolated native and recombinant S-layer proteins to form self-assembled mono- or double layers in suspension, at solid supports, the air-water interface, planar lipid films, liposomes, nanocapsules, and nanoparticles. The reassembly is entropy-driven and a fascinating example of matrix assembly following a multistage, non-classical pathway in which the process of S-layer protein folding is directly linked with assembly into extended clusters. Moreover, basic research on the structure, synthesis, genetics, assembly, and function of S-layer proteins laid the foundation for their application in novel approaches in biotechnology, biomimetics, synthetic biology, and nanotechnology. (topical review)

  15. S-layer architectures : extending the morphogenetic potential of S-layer protein self-assembly

    International Nuclear Information System (INIS)

    Schuster, D.

    2013-01-01

    Self-assembly of molecular building blocks is a common principle for bottom up based building principles in nature. One example are crystalline bacterial surface layers, termed S-layers, which are the most commonly observed cell surface structures in prokaryotic organisms. They recrystallize into highly ordered, porous protein meshworks with unit cell sizes of 3 to 30 nm and pore sizes of 2 to 8 nm. In this work, S-layers were self-assembled on various three dimensional scaffolds in order to fabricate novel S-layer architectures. Exploiting the stabilizing effect of silica deposited on the S-layer protein meshwork led to the construction of hollow S-layer nano-containers derived from coated liposomes. Transmission electron microscopy (TEM) techniques and release experiments with fluorescent dyes confirmed the dissolution of the supporting lipids. Silica deposition on different spherical particles in solution, as well as on planar S-layer coated surfaces, could be monitored by measuring the ζ-potential, the decline of monosilicic acid in solution, by using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis or by quartz crystal microbalance with dissipation monitoring (QCM-D). Both, ζ-potential and release experiments showed differences between silicified plain liposomes and silicified S-layer coated liposomes. In addition, nanocapsules with calcium carbonate cores served as another template for the construction of silica supported S-layer architectures. These were investigated by SEM and fluorescence microscopy after fluorescence labeling. Additional coating with polyelectrolytes increased the stability of the nanocapsules. Their mechanical properties were characterized by atomic force microscopy (AFM). The influence of silica deposition was investigated by AFM and SEM. Further on, emulsomes and gas filled lipid supported microbubbles may serve as other templates for the design of spherical protein constructs although extraction of the

  16. [Lipids of Aureobasidium (Pullularia) pullulans].

    Science.gov (United States)

    Elinov, N P; Iurlova, N A; Efimova, T P

    1975-01-01

    Fractional composition of free and bound lipids was studied in Aureobasidium (Pullularia) pullulans 8 by preparative TLC on Silufol. Bound lipids contained a fraction (27.76 +/- 0.5%) of dark brown colour, similar to melanin. The composition of fatty acids was studied by GLC. The following fatty acids were identified and determined quantitatively: C12:0, C14:0, C15:0, C16:0, C18:0, C18:1+C15:2. The following fatty acids predominated in free and bound lipids: C16:0, C18:1+C18:2. The ratio between unsaturated and saturated fatty acids in all fractions of free and bound lipids was more than unity. The following parameters were determined for lipids; ester number (173.89 and 178.53); iodine number (44.1 and 33.10), and saponification number (181.17 and 206.03) (the values are given for free and bound lipids, respectively).

  17. Effect of Cholesterol on the Stability and Lubrication Efficiency of Phosphatidylcholine Surface Layers

    NARCIS (Netherlands)

    Sorkin, Raya; Kampf, Nir; Klein, Jacob

    2017-01-01

    The lubrication properties of saturated PC lipid vesicles containing high cholesterol content under high loads were examined by detailed surface force balance measurements of normal and shear forces between two surface-attached lipid layers. Forces between two opposing mica surfaces bearing

  18. Supercritical fluid extraction and characterization of lipids from algae Scenedesmus obliquus

    Science.gov (United States)

    Choi, K. J.; Nakhost, Z.; Krukonis, V. J.; Karel, M.

    1987-01-01

    Lipids were extracted from a protein concentrate of green algae (Scenedesmus obliquus), using a one-step supercritical carbon dioxide extraction procedure in presence of ethanol as an entrainer, and were characterized. The compositions of neutral lipids, glycolipids, and phospholipids, separated into individual components by column, thin-layer, and gas-liquid chromatography procedures, are presented. Fatty acid composition patterns indicated that the major fatty acids were 16:0, 16:1, 16:2, 16:3, 16:4, 18:1, 18:2, and 18:3. The lipids of S. obliquus were found to contain relatively high concentrations of polyunsaturated fatty acids and essential fatty acids.

  19. Qualitative composition of the lipids of the wood of scotch pine

    Energy Technology Data Exchange (ETDEWEB)

    Fuksman, I.L.; Pon' kina, N.A.

    1984-01-01

    The ether extract of Pinus sylvestris contained 87.43% neutral lipids and resin acids, 10.85% galacto lipids, and 1.71% phospholipids. The predominant component of phospholipids was phorphatidylcholine, accounting for 62.10% of the total. The other components of phospholipids were diphosphatidylethanolamine (14.00%), phosphatidylglycerol and phosphatidylethanolamine (together accounting for 14.64%), phosphatidylylinositol (5.78%), and phosphatidic acid (1.04%). The acid part of the extract was determined by gas-liquid chromatography to contain 52 carboxylic acids, of which 44 were fatty acids and 8 were resin acids. The composition of the lipids was determined by thin-layer chromatography.

  20. 1H-NMR of human blood lipids in cases of malignant and benign tumors

    International Nuclear Information System (INIS)

    Yushmanov, V.E.; Kotrikadze, N.G.; Pershin, A.D.; Dzhishkariani, O.S.; Tsartsidze, M.A.; Lomsadze, B.A.; Sibel'dina, L.A.

    1989-01-01

    High resolution 1 H-NMR (360MH z ) combined with thin-layer chromatography was used to study profile and molecular structure changes of inverted micelles of human blood developing in patients with malignant and benign tumors of the breast and uterus. Alterations were demonstrated in relative intensities of some lipid NMR peaks in tumor, as compared to normal blood. Changes in blood - lipid levels, e.g. cholesterol, in tumor affect lipid structural and dynamical status thus elucidating NMR-regularities obtained

  1. Defining Lipid Transport Pathways in Animal Cells

    Science.gov (United States)

    Pagano, Richard E.; Sleight, Richard G.

    1985-09-01

    A new technique for studying the metabolism and intracellular transport of lipid molecules in living cells based on the use of fluorescent lipid analogs is described. The cellular processing of various intermediates (phosphatidic acid and ceramide) and end products (phosphatidylcholine and phosphatidylethanolamine) in lipid biosynthesis is reviewed and a working model for compartmentalization during lipid biosynthesis is presented.

  2. Transformation of lipid bodies related to hydrocarbon accumulation in a green alga, Botryococcus braunii (Race B.

    Directory of Open Access Journals (Sweden)

    Reiko Suzuki

    Full Text Available The colonial microalga Botryococcus braunii accumulates large quantities of hydrocarbons mainly in the extracellular space; most other oleaginous microalgae store lipids in the cytoplasm. Botryococcus braunii is classified into three principal races (A, B, and L based on the types of hydrocarbons. Race B has attracted the most attention as an alternative to petroleum by its higher hydrocarbon contents than the other races and its hydrocarbon components, botryococcenes and methylsqualenes, both can be readily converted into biofuels. We studied race B using fluorescence and electron microscopy, and clarify the stage when extracellular hydrocarbon accumulation occurs during the cell cycle, in a correlation with the behavior and structural changes of the lipid bodies and discussed development of the algal colony. New accumulation of lipids on the cell surface occurred after cell division in the basolateral region of daughter cells. While lipid bodies were observed throughout the cell cycle, their size and inclusions were dynamically changing. When cells began dividing, the lipid bodies increased in size and inclusions until the extracellular accumulation of lipids started. Most of the lipids disappeared from the cytoplasm concomitant with the extracellular accumulation, and then reformed. We therefore hypothesize that lipid bodies produced during the growth of B. braunii are related to lipid secretion. New lipids secreted at the cell surface formed layers of oil droplets, to a maximum depth of six layers, and fused to form flattened, continuous sheets. The sheets that combined a pair of daughter cells remained during successive cellular divisions and the colony increased in size with increasing number of cells.

  3. Layering and Ordering in Electrochemical Double Layers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yihua [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Kawaguchi, Tomoya [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Pierce, Michael S. [Rochester Institute of Technology, School of Physics and Astronomy, Rochester, New York 14623, United States; Komanicky, Vladimir [Faculty of Science, Safarik University, 041 54 Kosice, Slovakia; You, Hoydoo [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States

    2018-02-26

    Electrochemical double layers (EDL) form at electrified interfaces. While Gouy-Chapman model describes moderately charged EDL, formation of Stern layers was predicted for highly charged EDL. Our results provide structural evidence for a Stern layer of cations, at potentials close to hydrogen evolution in alkali fluoride and chloride electrolytes. Layering was observed by x-ray crystal truncation rods and atomic-scale recoil responses of Pt(111) surface layers. Ordering in the layer is confirmed by glancing-incidence in-plane diffraction measurements.

  4. Modeling growth, lipid accumulation and lipid turnover in submerged batch cultures of Umbelopsis isabellina

    NARCIS (Netherlands)

    Meeuwse, P.; Akbari, P.; Tramper, J.; Rinzema, A.

    2012-01-01

    The production of lipids by oleaginous yeast and fungi becomes more important because these lipids can be used for biodiesel production. To understand the process of lipid production better, we developed a model for growth, lipid production and lipid turnover in submerged batch fermentation. This

  5. Lipid nanoparticle interactions and assemblies

    Science.gov (United States)

    Preiss, Matthew Ryan

    Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron

  6. A Clinical Study of Subtype-based Prevalence of Dry Eye.

    Science.gov (United States)

    Rege, Aditya; Kulkarni, Varsha; Puthran, Neelam; Khandgave, Tejaswini

    2013-10-01

    Dry Eye is a multifactorial disease of the tearfilm and the ocular surface which may be due to reduced tear production or excessive tear evaporation resulting in discomfort, visual disturbance, and tear film instability with a potential damage to the ocular surface. Various population-based studies have been done to find out the prevalence and the magnitude of the problem. Women Health Study reported prevalence of 7.8% after screening 36995 subjects above 49 years by interview. The prevalence reported by Blue Mountain Study was 15.3% .The Beaver Dam Study and Shiphai Eye studies are other studies reporting prevalence of 14.5% and 33.7% respectively. McMonnies questionnaire is a widely used screening instrument for Dry-Eye syndromes with sensitivity reportedly varying between 87% and 98% and specificity between 87% and 97%. Prevalence studies use McMonnie's questionnaire for screening individuals for Dry Eye, whereafter tests like Schirmer's test, Tear Film Break Up Time test, Rose Bengal test, Lissamine Green test and Meibomian Gland Dysfunction test are useful for further evaluation. While these tests help to differentiate the subtypes of Dry Eye such as Lipid Anomaly Dry Eye, Aqueous Tear Deficiency and Mucin Layer Deficiency, however, their sensitivity and specificity has not been widely studied. Additionally, very few studies have reported the prevalence of the various subtypes of Dry Eye. To determine the subtype-based prevalence of Dry Eye, to study the specificity and sensitivity of clinical tests for Dry Eye and to correlate McMonnies questionnaire with Dry Eye tests results. A prospective, cross-sectional, observational study, duly approved by the Institutional Ethics Committee, was conducted from October 2010 to April 2012. A total of 4750 subjects above 18 yrs of age were screened by the McMonnies questionnaire. Respondents having a score greater than 14.5 were subjected to clinical Dry Eye tests. The data obtained was analyzed using chi-square test. p

  7. Rapid induction of lipid droplets in Chlamydomonas reinhardtii and Chlorella vulgaris by Brefeldin A.

    Directory of Open Access Journals (Sweden)

    Sangwoo Kim

    Full Text Available Algal lipids are the focus of intensive research because they are potential sources of biodiesel. However, most algae produce neutral lipids only under stress conditions. Here, we report that treatment with Brefeldin A (BFA, a chemical inducer of ER stress, rapidly triggers lipid droplet (LD formation in two different microalgal species, Chlamydomonas reinhardtii and Chlorella vulgaris. LD staining using Nile red revealed that BFA-treated algal cells exhibited many more fluorescent bodies than control cells. Lipid analyses based on thin layer chromatography and gas chromatography revealed that the additional lipids formed upon BFA treatment were mainly triacylglycerols (TAGs. The increase in TAG accumulation was accompanied by a decrease in the betaine lipid diacylglyceryl N,N,N-trimethylhomoserine (DGTS, a major component of the extraplastidic membrane lipids in Chlamydomonas, suggesting that at least some of the TAGs were assembled from the degradation products of membrane lipids. Interestingly, BFA induced TAG accumulation in the Chlamydomonas cells regardless of the presence or absence of an acetate or nitrogen source in the medium. This effect of BFA in Chlamydomonas cells seems to be due to BFA-induced ER stress, as supported by the induction of three homologs of ER stress marker genes by the drug. Together, these results suggest that ER stress rapidly triggers TAG accumulation in two green microalgae, C. reinhardtii and C. vulgaris. A further investigation of the link between ER stress and TAG synthesis may yield an efficient means of producing biofuel from algae.

  8. Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L

    2008-10-30

    Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.

  9. Dyeing Industry Effluent System as Lipid Production Medium of Neochloris sp. for Biodiesel Feedstock Preparation

    Directory of Open Access Journals (Sweden)

    Vidyadharani Gopalakrishnan

    2014-01-01

    Full Text Available Microalgae lipid feedstock preparation cost was an important factor in increasing biodiesel fuel hikes. This study was conducted with the concept of implementing an effluent wastewater as lipid production medium for microalgae cultivation. In our study textile dyeing industry effluent was taken as a lipid production medium for Neochloris sp. cultivation. The changes in physicochemical analysis of effluent before and after Neochloris sp. treatment were recorded using standard procedures and AAS analysis. There was especially a reduction in heavy metal like lead (Pb concentration from 0.002 ppm to 0.001 ppm after Neochloris sp. treatment. Neochloris sp. cultivated in Bold Basal Medium (BBM (specific algal medium produced 41.93% total lipid and 36.69% lipid was produced in effluent based cultivation. Surprisingly Neochloris sp. cultivated in effluent was found with enhanced neutral lipid content, and it was confirmed by Nile red fluorescence assay. Further the particular enrichment in oleic acid content of the cells was confirmed with thin layer chromatography (TLC with oleic acid pure (98% control. The overall results suggested that textile dyeing industry effluent could serve as the best lipid productive medium for Neochloris sp. biodiesel feedstock preparation. This study was found to have a significant impact on reducing the biodiesel feedstock preparation cost with simultaneous lipid induction by heavy metal stress to microalgae.

  10. Monoolein lipid phases as incorporation and enrichment materials for membrane protein crystallization.

    Directory of Open Access Journals (Sweden)

    Ellen Wallace

    Full Text Available The crystallization of membrane proteins in amphiphile-rich materials such as lipidic cubic phases is an established methodology in many structural biology laboratories. The standard procedure employed with this methodology requires the generation of a highly viscous lipidic material by mixing lipid, for instance monoolein, with a solution of the detergent solubilized membrane protein. This preparation is often carried out with specialized mixing tools that allow handling of the highly viscous materials while minimizing dead volume to save precious membrane protein sample. The processes that occur during the initial mixing of the lipid with the membrane protein are not well understood. Here we show that the formation of the lipidic phases and the incorporation of the membrane protein into such materials can be separated experimentally. Specifically, we have investigated the effect of different initial monoolein-based lipid phase states on the crystallization behavior of the colored photosynthetic reaction center from Rhodobacter sphaeroides. We find that the detergent solubilized photosynthetic reaction center spontaneously inserts into and concentrates in the lipid matrix without any mixing, and that the initial lipid material phase state is irrelevant for productive crystallization. A substantial in-situ enrichment of the membrane protein to concentration levels that are otherwise unobtainable occurs in a thin layer on the surface of the lipidic material. These results have important practical applications and hence we suggest a simplified protocol for membrane protein crystallization within amphiphile rich materials, eliminating any specialized mixing tools to prepare crystallization experiments within lipidic cubic phases. Furthermore, by virtue of sampling a membrane protein concentration gradient within a single crystallization experiment, this crystallization technique is more robust and increases the efficiency of identifying productive

  11. Enhanced dissolved lipid production as a response to the sea surface warming

    Science.gov (United States)

    Novak, Tihana; Godrijan, Jelena; Pfannkuchen, Daniela Marić; Djakovac, Tamara; Mlakar, Marina; Baricevic, Ana; Tanković, Mirta Smodlaka; Gašparović, Blaženka

    2018-04-01

    The temperature increase in oceans reflects on marine ecosystem functioning and surely has consequences on the marine carbon cycle and carbon sequestration. In this study, we examined dissolved lipid, lipid classes and dissolved organic carbon (DOC) production in the northern Adriatic Sea, isolated diatom Chaetoceros pseudocurvisetus batch cultures grown in a wide temperature range (10-30 °C) and in contrasting nutrient regimes, phosphorus (P)-depleted and P-replete conditions. Additionally, lipids and DOC were analyzed in the northern Adriatic (NA) in two stations characterized with different P availability, occupied from February to August 2010 that covered a temperature range from 9.3 to 31.1 °C. To gain insight into factors governing lipid and lipid classes' production in the NA, apart from temperature (T), Chlorophyll a, phytoplankton community abundance and structure, nutrient concentrations were measured together with hydrographic parameters. We found enhanced accumulation of dissolved lipids, particulary glycolipids, with increasing T, especially during the highest in situ temperature. The effect of T on enhanced dissolved lipid release is much more pronounced under P-deplete conditions indicating that oligotrophic regions might be more vulnerable to T rise. Temperature between 25 and 30 °C is a threshold T range for C. pseudocurvisetus, at which a significant part of lipid production is directed toward the dissolved phase. Unlike monocultures, there are multiple factors influencing produced lipid composition, distribution and cycling in the NA that may counteract the T influence. The possible role of enhanced dissolved lipid concentration for carbon sequestration at elevated T is discussed. On the one hand, lipids are buoyant and do not sink, which enhances their retention at the surface layer. In addition, they are surface active, and therefore prone to adsorb on sinking particles, contributing to the C sequestration.

  12. Covalent modification of hepatic microsomal lipids of rats by carbon tetrachloride

    International Nuclear Information System (INIS)

    Kaphalia, B.S.; Ansari, G.A.

    1989-01-01

    The present study was undertaken to isolate and identify various lipids bound to 14C label during hepatic microsomal metabolism of 14CCl4 in vitro under anaerobic conditions and in vivo in rats. The two major radioactive fractions identified by thin-layer chromatography each for neutral lipids and phospholipids from in vitro and in vivo experiments corresponded to fatty acids and triglycerides and to phosphatidylcholine (PC) and phosphatidylethanolamine (PE), respectively. Approximately 89% of the radioactivity associated with phospholipids was found in PC and PE fractions. Hydrolysis of PC and PE with phospholipase A2 released about 50% of the total radioactivity as lipid moieties corresponding to fatty acids. The radioactive neutral lipids and the lipid moieties hydrolyzed from PC and PE were methylated with boron trifluoride in methanol. These methylated lipids were separated by reversed-phase high-performance liquid chromatography (HPLC), and the elution profiles of 14C label found for the lipids obtained from in vitro experiments were similar to those from in vivo. The major radioactive fractions eluted immediately after methyl oleate were identified as trichloromethyloctadecenoic and trichloromethyleicosatrienoic acid methyl esters by chemical ionization mass spectrometry. The mass spectral analysis of these fractions also indicated the formation of dichlorocarbene adduct of oleic acid. However, similar mass spectrometric detection of trichloromethylated lipids was not evident in neutral lipids and phospholipids isolated from in vivo studies. The 14C-labeled lipids eluted as a nonpolar fraction exhibited a high molecular weight containing more than three chlorines. Dimerization and cross-linking of trichloromethylated lipids based on HPLC and mass spectral analysis are also discussed in this paper

  13. Lipids, lipid droplets and lipoproteins in their cellular context; an ultrastructural approach

    NARCIS (Netherlands)

    Mesman, R.J.

    2013-01-01

    Lipids are essential for cellular life, functioning either organized as bilayer membranes to compartmentalize cellular processes, as signaling molecules or as metabolic energy storage. Our current knowledge on lipid organization and cellular lipid homeostasis is mainly based on biochemical data.

  14. Human Intestinal Fluid Layer Separation: The Effect On Colloidal Structures & Solubility Of Lipophilic Compounds.

    Science.gov (United States)

    Danny, Riethorst; Amitava, Mitra; Filippos, Kesisoglou; Wei, Xu; Jan, Tack; Joachim, Brouwers; Patrick, Augustijns

    2018-05-23

    In addition to individual intestinal fluid components, colloidal structures are responsible for enhancing the solubility of lipophilic compounds. The present study investigated the link between as well as the variability in the ultrastructure of fed state human intestinal fluids (FeHIF) and their solubilizing capacity for lipophilic compounds. For this purpose, FeHIF samples from 10 healthy volunteers with known composition and ultrastructure were used to determine the solubility of four lipophilic compounds. In light of the focus on solubility and ultrastructure, the study carefully considered the methodology of solubility determination in relation to colloid composition and solubilizing capacity of FeHIF. To determine the solubilizing capacity of human and simulated intestinal fluids, the samples were saturated with the compound of interest, shaken for 24 h, and centrifuged. When using FeHIF, solubilities were determined in the micellar layer of FeHIF, i.e. after removing the upper (lipid) layer (standard procedure), as well as in 'full' FeHIF (without removal of the upper layer). Compound concentrations were determined using HPLC-UV/fluorescence. To link the solubilizing capacity with the ultrastructure, all human and simulated fluids were imaged using transmission electron microscopy (TEM) before and after centrifugation and top layer (lipid) removal. Comparing the ultrastructure and solubilizing capacity of individual FeHIF samples demonstrated a high intersubject variability in postprandial intestinal conditions. Imaging of FeHIF after removal of the upper layer clearly showed that only micellar structures remain in the lower layer. This observation suggests that larger colloids such as vesicles and lipid droplets are contained in the upper, lipid layer. The solubilizing capacity of most FeHIF samples substantially increased with inclusion of this lipid layer. The relative increase in solubilizing capacity upon inclusion of the lipid layer was most pronounced

  15. Oral omega-6 essential fatty acid treatment in contact lens associated dry eye.

    Science.gov (United States)

    Kokke, Karolien H; Morris, Judith A; Lawrenson, John G

    2008-06-01

    Symptoms of dry eye are commonly reported in contact lens wearers and are a frequent cause of non-tolerance. The purpose of the present study is to evaluate the effects of oral treatment with particular omega-6 fatty acids in the form of evening primrose oil (EPO) on subjective symptoms, ocular surface signs and tear film characteristic in patients with contact lens associated dry eye. The study design was randomised, double-masked and placebo controlled. 76 female soft contact lens wearers were treated for 6 months with either EPO or placebo (olive oil). Subjects underwent three examinations (baseline, 3 and 6 months). At each examination subjects were given a questionnaire relating to lens comfort and dry eye symptoms and underwent a series of tests of tear film characteristics (tear meniscus height, break-up time), meibomian gland function (lipid layer thickness and quality) and ocular surface parameters (hyperaemia and staining). The EPO group showed a significant improvement in the specific symptom of 'dryness' at 3 and 6 months (porally administered omega-6 fatty acids in alleviating dry eye symptoms and improving overall lens comfort in patients suffering from contact lens associated dry eye.

  16. Gene therapy for lipid disorders

    Directory of Open Access Journals (Sweden)

    Rader Daniel J

    2000-10-01

    Full Text Available Abstract Lipid disorders are associated with atherosclerotic vascular disease, and therapy is associated with a substantial reduction in cardiovascular events. Current approaches to the treatment of lipid disorders are ineffective in a substantial number of patients. New therapies for refractory hypercholesterolemia, severe hypertriglyceridemia, and low levels of high-density lipoprotein cholesterol are needed: somatic gene therapy is one viable approach. The molecular etiology and pathophysiology of most of the candidate diseases are well understood. Animal models exist for the diseases and in many cases preclinical proof-of-principle studies have already been performed. There has been progress in the development of vectors that provide long-term gene expression. New clinical gene therapy trials for lipid disorders are likely to be initiated within the next few years.

  17. Analysis of Lipid Experiments (ALEX)

    DEFF Research Database (Denmark)

    Husen, Peter; Tarasov, Kirill; Katafiasz, Maciej

    2013-01-01

    Global lipidomics analysis across large sample sizes produces high-content datasets that require dedicated software tools supporting lipid identification and quantification, efficient data management and lipidome visualization. Here we present a novel software-based platform for streamlined data...... processing, management and visualization of shotgun lipidomics data acquired using high-resolution Orbitrap mass spectrometry. The platform features the ALEX framework designed for automated identification and export of lipid species intensity directly from proprietary mass spectral data files......, and an auxiliary workflow using database exploration tools for integration of sample information, computation of lipid abundance and lipidome visualization. A key feature of the platform is the organization of lipidomics data in "database table format" which provides the user with an unsurpassed flexibility...

  18. Protein-lipid interactions in concentrated infant formula

    International Nuclear Information System (INIS)

    Rowley, B.O.; Richardson, T.

    1985-01-01

    Radiolabeled milk proteins ([carbon-14] β-lactoglobulin or [carbon-14] kappa-casein) were added to raw skim milk used to prepare concentrated humanized infant formula. Ultracentrifugation of the sterilized product allowed separation of three fractions: lipids and the proteins associated with them; free casein micelles and other dense particles; and the fluid phase. Distribution of radiolabeled tracer proteins or of protein measured by chemical methods among these three phases varied significantly with differences in processing conditions (time and temperature of sterilization) or amount of certain additives (potassium hydroxide or urea). In the range of 0 to 8 meq/L of potassium hydroxide added to the formula after homogenization but before sterilization, the lipid layer content of carbon-14 from [carbon-14] kappa-casein in the sterilized product decreased by 4.7% for each 1 meq/L of added potassium hydroxide. Lipid layer content of protein decreased by 2 g/L ( of a total of 32 g/L) for each 1 meq/L potassium hydroxide

  19. Effects of thiosulfonates on the lipid composition of rat tissues

    Directory of Open Access Journals (Sweden)

    A. Z. Pylypets

    2017-12-01

    Full Text Available Thiosulfonates are synthetic analogs of organic sulfur-containing compounds isolated from plants. Recent studies have shown that these substances lowering cholesterol content in the body, are effective against hyperlipidemia. Therefore, the aim of our investigation was to study the effect of synthesized thiosulfonates on the content of lipids and their spectrum in rats blood, liver and kidney. The amount of total lipids and their fractional profile were determined by thin-layer chromatography. The administration of methyl-, ethyl-, and allylthiosulfonates at a dose of 300 mg/kg of body weight did not cause significant changes in the content of total lipids and phospholipids, but led to the redistribution of their classes in the examined tissues. The content of triacylglycerols in the blood plasma under the action of ethyl- and allylthiosulfonates was decreased by 29.14 and 23.19% (P < 0.05-0.01, respectively, whereas the injection with methyl- and ethylthiosulfonates was accompanied by a significant decrease in mono-, di-, triglycerides and free fatty acids in the liver compared to control. The most significant changes in the lipid profile of kidney tissue were detected under the action of methylthiosulfonate.

  20. Sensing voltage across lipid membranes

    Science.gov (United States)

    Swartz, Kenton J.

    2009-01-01

    The detection of electrical potentials across lipid bilayers by specialized membrane proteins is required for many fundamental cellular processes such as the generation and propagation of nerve impulses. These membrane proteins possess modular voltage-sensing domains, a notable example being the S1-S4 domains of voltage-activated ion channels. Ground-breaking structural studies on these domains explain how voltage sensors are designed and reveal important interactions with the surrounding lipid membrane. Although further structures are needed to fully understand the conformational changes that occur during voltage sensing, the available data help to frame several key concepts that are fundamental to the mechanism of voltage sensing. PMID:19092925

  1. Blood lipid metabolites and meat lipid peroxidation responses of ...

    African Journals Online (AJOL)

    Esnart Mukumbo

    2017-06-19

    Jun 19, 2017 ... Fat and protein contents of thigh muscle and abdominal fat weight were measured and reported. Chickens fed LPO had greater serum triacylglycerol and very low ... favour lipid peroxidation, inhibit synthesis of higher homologous of ... The ambient temperature was gradually decreased from 33 °C at first.

  2. Blood lipid metabolites and meat lipid peroxidation responses of ...

    African Journals Online (AJOL)

    Blood samples were collected from broilers to evaluate serum biochemical metabolites on day 41. Thigh meat samples were provided and analysed after 1, 5 and 10 days' storage to evaluate lipid peroxidation at the end of the experiment. Fat and protein contents of thigh muscle and abdominal fat weight were measured ...

  3. Multinuclear NMR studies of single lipid bilayers supported in cylindrical aluminum oxide nanopores.

    Science.gov (United States)

    Gaede, Holly C; Luckett, Keith M; Polozov, Ivan V; Gawrisch, Klaus

    2004-08-31

    Lipid bilayers were deposited inside the 0.2 microm pores of anodic aluminum oxide (AAO) filters by extrusion of multilamellar liposomes and their properties studied by 2H, 31P, and 1H solid-state NMR. Only the first bilayer adhered strongly to the inner surface of the pores. Additional layers were washed out easily by a flow of water as demonstrated by 1H magic angle spinning NMR experiments with addition of Pr3+ ions to shift accessible lipid headgroup resonances. A 13 mm diameter Anopore filter of 60 microm thickness oriented approximately 2.5 x 10(-7) mol of lipid as a single bilayer, corresponding to a total membrane area of about 500 cm2. The 2H NMR spectra of chain deuterated POPC are consistent with adsorption of wavy, tubular bilayers to the inner pore surface. By NMR diffusion experiments, we determined the average length of those lipid tubules to be approximately 0.4 microm. There is evidence for a thick water layer between lipid tubules and the pore surface. The ends of tubules are well sealed against the pore such that Pr3+ ions cannot penetrate into the water underneath the bilayers. We successfully trapped poly(ethylene glycol) (PEG) with a molecular weight of 8000 in this water layer. From the quantity of trapped PEG, we calculated an average water layer thickness of 3 nm. Lipid order parameters and motional properties are unperturbed by the solid support, in agreement with existence of a water layer. Such unperturbed, solid supported membranes are ideal for incorporation of membrane-spanning proteins with large intra- and extracellular domains. The experiments suggest the promise of such porous filters as membrane support in biosensors.

  4. Targeted delivery of 10-hydroxycamptothecin to human breast cancers by cyclic RGD-modified lipid-polymer hybrid nanoparticles.

    Science.gov (United States)

    Yang, Zhe; Luo, Xingen; Zhang, Xiaofang; Liu, Jie; Jiang, Qing

    2013-04-01

    Lipid-polymer hybrid nanoparticles (NPs) combining the positive attributes of both liposomes and polymeric NPs are increasingly being considered as promising candidates to carry therapeutic agents safely and efficiently into targeted sites. Herein, a modified emulsification technique was developed and optimized for the targeting lipid-polymer hybrid NPs fabrication; the surface properties and stability of the hybrid NPs were systematically investigated, which confirmed that the hybrid NPs consisted of a poly (lactide-co-glycolide) core with ∼90% surface coverage of the lipid monolayer and a ∼4.4 nm hydrated polyethylene glycol (PEG) shell. Optimization results showed that the lipid:polymer mass ratio and the lipid-PEG:lipid molar ratio could affect the size, lipid association efficiency and stability of hybrid NPs. Furthermore, a model chemotherapy drug, 10-hydroxycamptothecin, was encapsulated into hybrid NPs with a higher drug loading compared to PLGA NPs. Surface modification of the lipid layer and the PEG conjugated targeting ligand did not affect their drug release kinetics. Finally, the cytotoxicity and cellular uptake studies indicated that the lipid coverage and the c(RGDyk) conjugation of the hybrid NPs gained a significantly enhanced ability of cell killing and endocytosis. Our results suggested that lipid-polymer hybrid NPs prepared by the modified emulsion technique have great potential to be utilized as an engineered drug delivery system with precise control ability of surface targeting modification.

  5. Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution

    Energy Technology Data Exchange (ETDEWEB)

    Anantachaisilp, Suranan; Smith, Siwaporn Meejoo [Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400 (Thailand); Treetong, Alongkot; Ruktanonchai, Uracha Rungsardthong [National Nanotechnology Center, National Science and Technology Development Agency, 111 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand); Pratontep, Sirapat [College of KMITL Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Bangkok (Thailand); Puttipipatkhachorn, Satit, E-mail: uracha@nanotec.or.th [Department of Manufacturing Pharmacy, Faculty of Pharmacy, Mahidol University, Bangkok 10400 (Thailand)

    2010-03-26

    Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of {gamma}-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812 as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the {gamma}-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance ({sup 1}H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the {sup 1}H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of {gamma}-oryzanol inside the lipid nanoparticles, the {sup 1}H-NMR revealed that the chemical shifts of the liquid lipid in {gamma}-oryzanol loaded systems were found at rather higher field than those in {gamma}-oryzanol free systems, suggesting incorporation of {gamma}-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of {gamma}-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models

  6. Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution

    Science.gov (United States)

    Anantachaisilp, Suranan; Meejoo Smith, Siwaporn; Treetong, Alongkot; Pratontep, Sirapat; Puttipipatkhachorn, Satit; Rungsardthong Ruktanonchai, Uracha

    2010-03-01

    Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of γ-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812® as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the γ-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance (1H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the 1H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of γ-oryzanol inside the lipid nanoparticles, the 1H-NMR revealed that the chemical shifts of the liquid lipid in γ-oryzanol loaded systems were found at rather higher field than those in γ-oryzanol free systems, suggesting incorporation of γ-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of γ-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of γ-oryzanol and

  7. Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution

    International Nuclear Information System (INIS)

    Anantachaisilp, Suranan; Smith, Siwaporn Meejoo; Treetong, Alongkot; Ruktanonchai, Uracha Rungsardthong; Pratontep, Sirapat; Puttipipatkhachorn, Satit

    2010-01-01

    Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of γ-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812 as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the γ-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance ( 1 H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the 1 H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of γ-oryzanol inside the lipid nanoparticles, the 1 H-NMR revealed that the chemical shifts of the liquid lipid in γ-oryzanol loaded systems were found at rather higher field than those in γ-oryzanol free systems, suggesting incorporation of γ-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of γ-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of γ-oryzanol and

  8. Properties of POPC/POPE supported lipid bilayers modified with hydrophobic quantum dots on polyelectrolyte cushions.

    Science.gov (United States)

    Kolasinska-Sojka, Marta; Wlodek, Magdalena; Szuwarzynski, Michal; Kereiche, Sami; Kovacik, Lubomir; Warszynski, Piotr

    2017-10-01

    The formation and properties of supported lipid bilayers (SLB) containing hydrophobic nanoparticles (NP) was studied in relation to underlying cushion obtained from selected polyelectrolyte multilayers. Lipid vesicles were formed from zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) in phosphate buffer (PBS). As hydrophobic nanoparticles - quantum dots (QD) with size of 3.8nm (emission wavelength of 420nm) were used. Polyelectrolyte multilayers (PEM) were constructed by the sequential, i.e., layer-by-layer (LbL) adsorption of alternately charged polyelectrolytes from their solutions. Liposomes and Liposome-QDs complexes were studied with Transmission Cryo-Electron Microscopy (Cryo-TEM) to verify the quality of vesicles and the position of QD within lipid bilayer. Deposition of liposomes and liposomes with quantum dots on polyelectrolyte films was studied in situ using quartz crystal microbalance with dissipation (QCM-D) technique. The fluorescence emission spectra were analyzed for both: suspension of liposomes with nanoparticles and for supported lipid bilayers containing QD on PEM. It was demonstrated that quantum dots are located in the hydrophobic part of lipid bilayer. Moreover, we proved that such QD-modified liposomes formed supported lipid bilayers and their final structure depended on the type of underlying cushion. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Lipid profile in cerebrovascular accidents.

    Science.gov (United States)

    Togha, Mansoureh; Gheini, Mohamad Reza; Ahmadi, Babak; Khashaiar, Patricia; Razeghi, Soodeh

    2011-01-01

    Changes in the lipid profile have been suggested as a risk factor for developing ischemic stroke. Their role in intra-cerebral hemorrhage, however, is not clear. The present study was designed to evaluate the lipid profile levels of patients who had experienced an acute stroke during the first 24-hour and to compare these levels in different patients suffering from the stroke, either hemorrhagic or ischemic, and healthy individuals. In this cross-sectional study, 258 consecutive patients with acute stroke admitted to the neurology department of our center during September 2006 and September 2007 were studied. As for the control group, 187 apparently healthy subjects living in the same community and matched for age and sex were selected. Lipid profile was measured and compared between the three groups. In the patients' group, 65 suffered from hemorrhagic stroke (group 1) and the other 193 had ischemic stroke (group 2). Except for TG values, there was no significant difference among the ischemic and hemorrhagic lipid profile. Age, cholesterol, and LDL influenced the risk of developing an ischemic stroke; TG was not reported as a risk factor or a protective one. While the comparison of data retrieved from patients suffering from hemorrhagic strokes with the controls, revealed LDL as the risk factor contributing to the development of ICH whereas TG was reported as a protective factor. It could be concluded that LDL level can be considered as a risk factor for both ischemic and hemorrhagic cerebral events.

  10. Future directions in lipid therapies.

    Science.gov (United States)

    Ansell, Benjamin

    2002-01-01

    Cholesterol management to reduce the burden of cardiovascular disease is a major public health concern. Despite widespread recognition of lipid abnormalities as cardiovascular risk factors, significant cardiovascular event reductions with cholesterol-lowering therapies, and dissemination of treatment guidelines, most high-risk patients are not at target lipid levels. In addition to lifestyle changes, four major drug classes are available to modify lipid levels: fibrates, niacin, resins, and statins. High efficacy and tolerability in clinical trials make statins the most widely prescribed of these agents. Newer, more potent members of this class and novel formulations of niacin and resins may provide more effective therapy for dyslipidemia with fewer side effects. Several agents in development (cholesterol-absorption inhibitors and ACAT inhibitors) exploit mechanisms of action complementary to those of current treatments and combined with statins may produce greater improvements in lipid profiles than are now possible. These innovations should enable a greater number of patients to achieve more aggressive cholesterol goals, thereby reducing the risk of cardiovascular events.

  11. Lipid flopping in the liver.

    Science.gov (United States)

    Linton, Kenneth J

    2015-10-01

    Bile is synthesized in the liver and is essential for the emulsification of dietary lipids and lipid-soluble vitamins. It is a complex mixture of amphiphilic bile acids (BAs; which act as detergent molecules), the membrane phospholipid phosphatidylcholine (PC), cholesterol and a variety of endogenous metabolites and waste products. Over the last 20 years, the combined effort of clinicians, geneticists, physiologists and biochemists has shown that each of these bile components is transported across the canalicular membrane of the hepatocyte by its own specific ATP-binding cassette (ABC) transporter. The bile salt export pump (BSEP) ABCB11 transports the BAs and drives bile flow from the liver, but it is now clear that two lipid transporters, ABCB4 (which flops PC into the bile) and the P-type ATPase ATP8B1/CDC50 (which flips a different phospholipid in the opposite direction) play equally critical roles that protect the biliary tree from the detergent activity of the bile acids. Understanding the interdependency of these lipid floppases and flippases has allowed the development of an assay to measure ABCB4 function. ABCB4 harbours numerous mis-sense mutations which probably reflects the spectrum of liver disease rooted in ABCB4 aetiology. Characterization of the effect of these mutations at the protein level opens the possibility for the development of personalized prognosis and treatment. © 2015 Authors; published by Portland Press Limited.

  12. Lipids in the cell: organisation regulates function.

    Science.gov (United States)

    Santos, Ana L; Preta, Giulio

    2018-06-01

    Lipids are fundamental building blocks of all cells and play important roles in the pathogenesis of different diseases, including inflammation, autoimmune disease, cancer, and neurodegeneration. The lipid composition of different organelles can vary substantially from cell to cell, but increasing evidence demonstrates that lipids become organised specifically in each compartment, and this organisation is essential for regulating cell function. For example, lipid microdomains in the plasma membrane, known as lipid rafts, are platforms for concentrating protein receptors and can influence intra-cellular signalling. Lipid organisation is tightly regulated and can be observed across different model organisms, including bacteria, yeast, Drosophila, and Caenorhabditis elegans, suggesting that lipid organisation is evolutionarily conserved. In this review, we summarise the importance and function of specific lipid domains in main cellular organelles and discuss recent advances that investigate how these specific and highly regulated structures contribute to diverse biological processes.

  13. Lipids and essential oils as antimicrobial agents

    National Research Council Canada - National Science Library

    Thormar, Halldor

    2011-01-01

    ... of Antimicrobial Lipids on Cell Membranes 20 1.7 Conclusions 21 Acknowledgements 21 References 22 2 Antibacterial Effects of Lipids: Historical Review (1881 to 1960) Halldor Thormar 2.1 Introduction 2....

  14. Characterization of Carbamazepine-Loaded Solid Lipid ...

    African Journals Online (AJOL)

    loaded solid lipid nanoparticles by RESS as well as their characterization has been achieved in this study. Keywords: Rapid expansion of supercritical fluid, Stearic acid, Solid lipid nanoparticles, Carbamazepine, Co-precipitation ...

  15. Exogenous ether lipids predominantly target mitochondria.

    Directory of Open Access Journals (Sweden)

    Lars Kuerschner

    Full Text Available Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high amounts of ether-phosphatidylcholine and ether-phosphatidylethanolamine. Both lipids were specifically labeled using the corresponding lyso-ether lipids, which we established as supreme precursors for lipid tagging. Polyfosine, a fluorescent analogue of the anti-neoplastic ether lipid edelfosine, accumulated to mitochondria and induced morphological changes and cellular apoptosis. These data indicate that edelfosine could exert its pro-apoptotic power by targeting and damaging mitochondria and thereby inducing cellular apoptosis. In general, this study implies an important role of mitochondria in ether lipid metabolism and intracellular ether lipid trafficking.

  16. A close collaboration of chitosan with lipid colloidal carriers for drug delivery applications.

    Science.gov (United States)

    Bugnicourt, Loïc; Ladavière, Catherine

    2017-06-28

    Chitosan and lipid colloids have separately shown a growing interest in the field of drug delivery applications. Their success is mainly due to their interesting physicochemical behaviors, as well as their biological properties such as bioactivity and biocompatibility. While chitosan is a well-known cationic polysaccharide with the ability to strongly interact with drugs and biological matrices through mainly electrostatic interactions, lipid colloids are carriers particularly recognized for the drug vectorization. In recent years, the combination of both entities has been considered because it offers new systems which gather the advantages of each of them to efficiently deliver various types of bioactive species. The purpose of this review is to describe these associations between chemically-unmodified chitosan chains (solubilized or dispersed) and lipid colloids (as nanoparticles or organized in lipid layers), as well as their potential in the drug delivery area so far. Three assemblies have mainly been reported in the literature: i) lipid nanoparticles (solid lipid nanoparticles or nanostructured lipid carriers) coated with chitosan chains, ii) lipid vesicles covered with chitosan chains, and iii) chitosan chains structured in nanoparticles with a lipid coating. Their elaboration processes, their physicochemical characterization, and their biological studies are detailed and discussed herein. The different bioactive species (drugs and bio(macro)molecules) incorporated in these assemblies, their maximal incorporation efficiency, and their loading capacity are also presented. This review reveals the versatility of these assemblies. Depending on the organization of lipids (i.e., nanoparticles or vesicles) and the state of polymer chains (i.e., solubilized or dispersed under the form of nanoparticles), a large variety of drugs can be successfully incorporated, and various routes of administration can be considered. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Factors affecting drug encapsulation and stability of lipid-polymer hybrid nanoparticles.

    Science.gov (United States)

    Cheow, Wean Sin; Hadinoto, Kunn

    2011-07-01

    Lipid-polymer hybrid nanoparticles are polymeric nanoparticles enveloped by lipid layers that combine the highly biocompatible nature of lipids with the structural integrity afforded by polymeric nanoparticles. Recognizing them as attractive drug delivery vehicles, antibiotics are encapsulated in the present work into hybrid nanoparticles intended for lung biofilm infection therapy. Modified emulsification-solvent-evaporation methods using lipid as surfactant are employed to prepare the hybrid nanoparticles. Biodegradable poly (lactic-co-glycolic acid) and phosphatidylcholine are used as the polymer and lipid models, respectively. Three fluoroquinolone antibiotics (i.e. levofloxacin, ciprofloxacin, and ofloxacin), which vary in their ionicity, lipophilicity, and aqueous solubility, are used. The hybrid nanoparticles are examined in terms of their drug encapsulation efficiency, drug loading, stability, and in vitro drug release profile. Compared to polymeric nanoparticles prepared using non-lipid surfactants, hybrid nanoparticles in general are larger and exhibit higher drug loading, except for the ciprofloxacin-encapsulated nanoparticles. Hybrid nanoparticles, however, are unstable in salt solutions, but the stability can be conferred by adding TPGS into the formulation. Drug-lipid ionic interactions and drug lipophilicity play important roles in the hybrid nanoparticle preparation. First, interactions between oppositely charged lipid and antibiotic (i.e. ciprofloxacin) during preparation cause failed nanoparticle formation. Charge reversal of the lipid facilitated by adding counterionic surfactants (e.g. stearylamine) must be performed before drug encapsulation can take place. Second, drug loading and the release profile are strongly influenced by drug lipophilicity, where more lipophilic drug (i.e. levofloxacin) exhibit a higher drug loading and a sustained release profile attributed to the interaction with the lipid coat. Copyright © 2011 Elsevier B.V. All

  18. Formation of milk lipids: a molecular perspective

    OpenAIRE

    McManaman, James L

    2009-01-01

    Lipids, primarily triglycerides, are major milk constituents of most mammals, providing a large percentage of calories, essential fatty acids and bioactive lipids required for neonatal growth and development. To meet the caloric and nutritional demands of newborns, the mammary glands of most species have evolved an enormous capacity to synthesize and secrete large quantities of lipids during lactation. Significant information exists regarding the physiological regulation of lipid metabolism i...

  19. Lipid Neuroprotectants and Traumatic Glaucomatous Neurodegeneration

    Science.gov (United States)

    2016-05-01

    not in individuals suffering from glaucoma (endogenous lipids ). The proposed research is to develop several such lipids as potential glaucoma...The proposed research will further assess the efficacy of the new lipids to lower IOP using mouse and monkeys that can develop glaucoma naturally or...of seminars and posters. Two high school students during summer (as part of their HHMI research program) learned hands-on about lipid analyses. A

  20. Polymorphism of lipid self-assembly systems

    International Nuclear Information System (INIS)

    Takahashi, Hiroshi

    2002-01-01

    When lipid molecules are dispersed into an aqueous medium, various self-organized structures are formed, depending on conditions (temperature, concentration, etc), in consequence of the amphipathic nature of the molecules. In addition, lipid self-assembly systems exhibit polymorphic phase transition behavior. Since lipids are one of main components of biomembranes, studies on the structure and thermodynamic properties of lipid self-assembly systems are fundamentally important for the consideration of the stability of biomembranes. (author)

  1. Electrodiffusion of Lipids on Membrane Surfaces

    OpenAIRE

    Zhou, Y. C.

    2011-01-01

    Random lateral translocation of lipids and proteins is a universal process on membrane surfaces. Local aggregation or organization of lipids and proteins can be induced when this lateral random diffusion is mediated by the electrostatic interactions and membrane curvature. Though the lateral diffusion rates of lipids on membrane of various compositions are measured and the electrostatic free energies of predetermined protein-membrane-lipid systems can be computed, the process of the aggregati...

  2. Metabolic incorporation of unsaturated fatty acids into boar spermatozoa lipids and de novo formation of diacylglycerols

    DEFF Research Database (Denmark)

    Svetlichnyy, V.; Müller, P.; Günther-Pomorski, Thomas

    2014-01-01

    Lipids play an important role in the maturation, viability and function of sperm cells. In this study, we examined the neutral and polar lipid composition of boar spermatozoa by thin-layer chromatography/mass spectrometry. Main representatives of the neutral lipid classes were diacylglycerols...... containing saturated (myristoyl, palmitoyl and stearoyl) fatty acyl residues. Glycerophosphatidylcholine and glycerophosphatidylethanolamine with alk(en)yl ether residues in the sn-1 position and unsaturated long chained fatty acyl residues in sn-2 position were identified as the most prominent polar lipids....... The only glycoglycerolipid was sulfogalactosylglycerolipid carrying 16:0-alkyl- and 16:0-acyl chains. Using stable isotope-labelling, the metabolic incorporation of exogenously supplied fatty acids was analysed. Boar spermatozoa incorporated hexadecenoic (16:1), octadecenoic (18:1), octadecadienoic (18...

  3. Proteins mediating intra- and intercellular transport of lipids and lipid-modified proteins

    NARCIS (Netherlands)

    Neumann, S.

    2008-01-01

    Proteins mediating intra- and intercellular transport of lipids and lipid-modified proteins In this thesis, I studied the intra- and intercellular transport of lipidic molecules, in particular glycosphingolipids and lipid-modified proteins. The first part focuses on the intracellular transport of

  4. Multimodal imaging of ocular surface of dry eye subjects

    Science.gov (United States)

    Zhang, Aizhong; Salahura, Gheorghe; Kottaiyan, Ranjini; Yoon, Geunyoung; Aquavella, James V.; Zavislan, James M.

    2016-03-01

    To study the relationship between the corneal lipid layer and the ocular surface temperature (OST), we conducted a clinical trial for 20 subjects. Subjects were clinically screened prior to the trial. Of the 20 subjects, 15 have Meibomian gland dysfunction (MGD), and 5 have aqueous-deficient dry eye (ADDE). A custom, circularly polarized illumination video tearscope measured the lipid layer thickness of the ocular tear film. A long-wave infrared video camera recorded the dynamic thermal properties of the ocular team film. The results of these two methods were analyzed and compared. Using principal component analysis (PCA) of the lipid layer distribution, we find that the 20 subjects could be categorized into five statistically significant groups, independent of their original clinical classification: thin (6 subjects), medium (5 subjects), medium and homogenous (3 subjects), thick (4 subjects), and very thick (2 subjects) lipids, respectively. We also conducted PCA of the OST data, and recategorized the subjects into two thermal groups by k-means clustering: one includes all ADDE subjects and some MGD subjects; the other includes the remaining MGD subjects. By comparing these two methods, we find that dry eye subjects with thin ( 40 nm), there is no strong correlation between the lipid layer thickness and heterogeneity and the OST patterns.

  5. Fabrication of dendrimer-releasing lipidic nanoassembly for cancer drug delivery.

    Science.gov (United States)

    Sun, Qihang; Ma, Xinpeng; Zhang, Bo; Zhou, Zhuxian; Jin, Erlei; Shen, Youqing; Van Kirk, Edward A; Murdoch, William J; Radosz, Maciej; Sun, Weilin

    2016-06-24

    An inherent dilemma in the use of nanomedicines for cancer drug delivery is their limited penetration into tumors due to their large size. We have demonstrated that dendrimer/lipid nanoassemblies can solve this problem by means of tumor-triggered disassembly and the release of small (several nanometers) dendrimers to facilitate tumor penetration. Herein, we report a general strategy for the fabrication of nanoassemblies from hydrophobic and hydrophilic dendrimers with phospholipids. Hydrophobic dendrimers could assemble with lipids via hydrophobic interactions, whereas hydrophilic dendrimers could only assemble with lipids in the presence of anionic surfactants via both electrostatic and hydrophobic interactions. The nanoassemblies of hydrophobic dendrimers/lipids were found to be capable of stripping off their lipid layers via fusion with the cell membrane and then intracellular or extracellular release of dendrimers, whereas the nanoassemblies of hydrophilic dendrimers/lipids were internalized via endocytosis and then released their dendrimers inside the cells. Therefore, these dendrimer/lipid nanoassemblies could be used for the delivery of different cancer drugs.

  6. Lipids and Fatty Acids in Algae: Extraction, Fractionation into Lipid Classes, and Analysis by Gas Chromatography Coupled with Flame Ionization Detector (GC-FID).

    Science.gov (United States)

    Guihéneuf, Freddy; Schmid, Matthias; Stengel, Dagmar B

    2015-01-01

    Despite the number of biochemical studies exploring algal lipids and fatty acid biosynthesis pathways and profiles, analytical methods used by phycologists for this purpose are often diverse and incompletely described. Potential confusion and potential variability of the results between studies can therefore occur due to change of protocols for lipid extraction and fractionation, as well as fatty acid methyl esters (FAME) preparation before gas chromatography (GC) analyses. Here, we describe a step-by-step procedure for the profiling of neutral and polar lipids using techniques such as solid-liquid extraction (SLE), thin-layer chromatography (TLC), and gas chromatography coupled with flame ionization detector (GC-FID). As an example, in this protocol chapter, analyses of neutral and polar lipids from the marine microalga Pavlova lutheri (an EPA/DHA-rich haptophyte) will be outlined to describe the distribution of fatty acid residues within its major lipid classes. This method has been proven to be a reliable technique to assess changes in lipid and fatty acid profiles in several other microalgal species and seaweeds.

  7. Presence and persistence of a highly ordered lipid phase state in the avian stratum corneum.

    Science.gov (United States)

    Champagne, Alex M; Pigg, Victoria A; Allen, Heather C; Williams, Joseph B

    2018-06-07

    To survive high temperatures in a terrestrial environment, animals must effectively balance evaporative heat loss and water conservation. In passerine birds, cutaneous water loss (CWL) is the primary avenue of water loss at thermoneutral temperatures and increases slightly as ambient temperature increases, indicating a change in the permeability of the skin. In the stratum corneum (SC), the outermost layer of the skin, lipids arranged in layers called lamellae serve as the primary barrier to CWL in birds. The permeability of these lamellae depends in large part on the ability of lipid molecules to pack closely together in an ordered orthorhombic phase state. However, as temperature increases, lipids of the SC become more disordered, and may pack in more permeable hexagonal or liquid crystalline phase states. In this study, we used Fourier transform infrared spectroscopy to monitor the phase state of lipids in the SC of house sparrows ( Passer domesticus ) at skin temperatures ranging from 25 to 50°C. As temperature increased, lipids became slightly more disordered, but remained predominantly in the orthorhombic phase, consistent with the small increase in CWL observed in house sparrows as ambient temperature increases. These results differ considerably from studies on mammalian SC, which find a predominantly hexagonal arrangement of lipids at temperatures above 37°C, and the increased order in avian SC may be explained by longer lipid chain length, scarcity of cholesterol and the presence of cerebrosides. Our results lend further insight into the arrangement and packing of individual lipid molecules in avian SC. © 2018. Published by The Company of Biologists Ltd.

  8. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    Energy Technology Data Exchange (ETDEWEB)

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J. [Univ. of Missouri, Columbia, MO (United States)

    1994-12-31

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer.

  9. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    International Nuclear Information System (INIS)

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J.

    1994-01-01

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer

  10. Correlated lateral phase separations in stacks of lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Takuma, E-mail: hoshino-takuma@ed.tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978 (Israel); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Komura, Shigeyuki, E-mail: komura@tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Andelman, David, E-mail: andelman@post.tau.ac.il [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978 (Israel); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China)

    2015-12-28

    Motivated by the experimental study of Tayebi et al. [Nat. Mater. 11, 1074 (2012)] on phase separation of stacked multi-component lipid bilayers, we propose a model composed of stacked two-dimensional Ising spins. We study both its static and dynamical features using Monte Carlo simulations with Kawasaki spin exchange dynamics that conserves the order parameter. We show that at thermodynamical equilibrium, due to strong inter-layer correlations, the system forms a continuous columnar structure for any finite interaction across adjacent layers. Furthermore, the phase separation shows a faster dynamics as the inter-layer interaction is increased. This temporal behavior is mainly due to an effective deeper temperature quench because of the larger value of the critical temperature, T{sub c}, for larger inter-layer interaction. When the temperature ratio, T/T{sub c}, is kept fixed, the temporal growth exponent does not increase and even slightly decreases as a function of the increased inter-layer interaction.

  11. Lipid processing in ionic liquids

    DEFF Research Database (Denmark)

    Lue, Bena-Marie; Guo, Zheng; Xu, Xuebing

    2007-01-01

    Ionic liquids (ILs) have been touted as “green” alternatives to traditional molecular solvents and have many unique properties which make them extremely desirable substitutes. Among their most attractive properties are their lack of vapour pressure, broad liquid range, strong solvating power and ...... and the ability to tailor properties of individual ILs to meet specific requirements. This article highlights current research as well as the vast potential of ILs for use as media for reactions, separation and processing in the lipid area....

  12. Proton permeation of lipid bilayers.

    Science.gov (United States)

    Deamer, D W

    1987-10-01

    Proton permeation of the lipid bilayer barrier has two unique features. First, permeability coefficients measured at neutral pH ranges are six to seven orders of magnitude greater than expected from knowledge of other monovalent cations. Second, proton conductance across planar lipid bilayers varies at most by a factor of 10 when pH is varied from near 1 to near 11. Two mechanisms have been proposed to account for this anomalous behavior: proton conductance related to contaminants of lipid bilayers, and proton translocation along transient hydrogen-bonded chains (tHBC) of associated water molecules in the membrane. The weight of evidence suggests that trace contaminants may contribute to proton conductance across planar lipid membranes at certain pH ranges, but cannot account for the anomalous proton flux in liposome systems. Two new results will be reported here which were designed to test the tHBC model. These include measurements of relative proton/potassium permeability in the gramicidin channel, and plots of proton flux against the magnitude of pH gradients. (1) The relative permeabilities of protons and potassium through the gramicidin channel, which contains a single strand of hydrogen-bonded water molecules, were found to differ by at least four orders of magnitude when measured at neutral pH ranges. This result demonstrates that a hydrogen-bonded chain of water molecules can provide substantial discrimination between protons and other cations. It was also possible to calculate that if approximately 7% of bilayer water was present in a transient configuration similar to that of the gramicidin channel, it could account for the measured proton flux. (2) The plot of proton conductance against pH gradient across liposome membranes was superlinear, a result that is consistent with one of three alternative tHBC models for proton conductance described by Nagle elsewhere in this volume.

  13. Reducible cationic lipids for gene transfer.

    Science.gov (United States)

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  14. Mechanics of Lipid Bilayer Membranes

    Science.gov (United States)

    Powers, Thomas R.

    All cells have membranes. The plasma membrane encapsulates the cell's interior, acting as a barrier against the outside world. In cells with nuclei (eukaryotic cells), membranes also form internal compartments (organelles) which carry out specialized tasks, such as protein modification and sorting in the case of the Golgi apparatus, and ATP production in the case of mitochondria. The main components of membranes are lipids and proteins. The proteins can be channels, carriers, receptors, catalysts, signaling molecules, or structural elements, and typically contribute a substantial fraction of the total membrane dry weight. The equilibrium properties of pure lipid membranes are relatively well-understood, and will be the main focus of this article. The framework of elasticity theory and statistical mechanics that we will develop will serve as the foundation for understanding biological phenomena such as the nonequilibrium behavior of membranes laden with ion pumps, the role of membrane elasticity in ion channel gating, and the dynamics of vesicle fission and fusion. Understanding the mechanics of lipid membranes is also important for drug encapsulation and delivery.

  15. Lipid bilayers suspended on microfabricated supports

    Science.gov (United States)

    Ogier, Simon D.; Bushby, Richard J.; Cheng, Yaling; Cox, Tim I.; Evans, Stephen D.; Knowles, Peter F.; Miles, Robert E.; Pattison, Ian

    2001-03-01

    The plasma membrane, that exists as part of many animal and plant cells, is a regulator for the transport of ions and small molecules across cell boundaries. Two main components involved are the phospholipid bilayer and the transport proteins. This paper details the construction of a micromachined support for bilayers (MSB) as a first step towards the development of highly selective and highly sensitive ion-channel based biosensors. The device consists of a ~100 micrometer hole in a polymeric support above a cavity that can hold ~25 nL of electrolyte. Electrodes attached to the structure allow the resistance of the membranes to be measured using d.c. conductivity. The MSB is made in two halves, using SU8 ultra-thick resist, which are subsequently bonded together to make the final structure. A layer of gold, surrounding the aperture, enables self-assembled monolayers of alkanethiols to be used to make the polymeric structure biocompatible. Lipid membranes have been formed over these holes with resistances comparable with those of natural membranes >10 MOhmcm^2. The ion-channel gramicidin has successfully been incorporated into the bilayer and its activity monitored. It is proposed that this type of device could be used not only for studying membrane transport phenomena but also as part of an ion-channel based biosensor.

  16. Fat & fabulous: bifunctional lipids in the spotlight.

    Science.gov (United States)

    Haberkant, Per; Holthuis, Joost C M

    2014-08-01

    Understanding biological processes at the mechanistic level requires a systematic charting of the physical and functional links between all cellular components. While protein-protein and protein-nucleic acid networks have been subject to many global surveys, other critical cellular components such as membrane lipids have rarely been studied in large-scale interaction screens. Here, we review the development of photoactivatable and clickable lipid analogues-so-called bifunctional lipids-as novel chemical tools that enable a global profiling of lipid-protein interactions in biological membranes. Recent studies indicate that bifunctional lipids hold great promise in systematic efforts to dissect the elaborate crosstalk between proteins and lipids in live cells and organisms. This article is part of a Special Issue entitled Tools to study lipid functions. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Lipid Biosynthesis as an Antifungal Target

    Directory of Open Access Journals (Sweden)

    Jiao Pan

    2018-04-01

    Full Text Available Lipids, commonly including phospholipids, sphingolipids, fatty acids, sterols, and triacylglycerols (TAGs, are important biomolecules for the viability of all cells. Phospholipids, sphingolipids, and sterols are important constituents of biological membranes. Many lipids play important roles in the regulation of cell metabolism by acting as signaling molecules. Neutral lipids, including TAGs and sterol esters (STEs, are important storage lipids in cells. In view of the importance of lipid molecules, this review briefly summarizes the metabolic pathways for sterols, phospholipids, sphingolipids, fatty acids, and neutral lipids in fungi and illustrates the differences between fungal and human (or other mammalian cells, especially in relation to lipid biosynthetic pathways. These differences might provide valuable clues for us to find target proteins for novel antifungal drugs. In addition, the development of lipidomics technology in recent years has supplied us with a shortcut for finding new antifungal drug targets; this ability is important for guiding our research on pathogenic fungi.

  18. Presentation of lipid antigens to T cells.

    Science.gov (United States)

    Mori, Lucia; De Libero, Gennaro

    2008-04-15

    T cells specific for lipid antigens participate in regulation of the immune response during infections, tumor immunosurveillance, allergy and autoimmune diseases. T cells recognize lipid antigens as complexes formed with CD1 antigen-presenting molecules, thus resembling recognition of MHC-peptide complexes. The biophysical properties of lipids impose unique mechanisms for their delivery, internalization into antigen-presenting cells, membrane trafficking, processing, and loading of CD1 molecules. Each of these steps is controlled at molecular and celular levels and determines lipid immunogenicity. Lipid antigens may derive from microbes and from the cellular metabolism, thus allowing the immune system to survey a large repertoire of immunogenic molecules. Recognition of lipid antigens facilitates the detection of infectious agents and the initiation of responses involved in immunoregulation and autoimmunity. This review focuses on the presentation mechanisms and specific recognition of self and bacterial lipid antigens and discusses the important open issues.

  19. Stratum Corneum Barrier Lipids in Cholesteatoma

    DEFF Research Database (Denmark)

    Svane-Knudsen, V; Halkier-Sørensen, L; Rasmussen, G

    2000-01-01

    emerged. When the corneocyte reaches the transitional stage to the stratum corneum, the Odland bodies accumulate near the cell membrane and discharge their contents of lipid and enzymes. The lipids are reorganized into multiple long sheets of lamellar structures that embrace the keratinized corneocytes......, as seen in the formation and maintenance of the cutaneous permeability barrier. In this study we draw the attention to the facts that the cholesteatoma epithelium is capable of producing not only cholesterol, but also several lipids, and that the lipid molecules are organized in multilamellar structures......Specimens from primary cholesteatomas were examined under the electron microscope using a lipid-retaining method that is best suited for intracellular lipids and a method that is best for intercellular lipids. In the stratum granulosum of the squamous epithelium, a large number of Odland bodies...

  20. Introduction to fatty acids and lipids.

    Science.gov (United States)

    Burdge, Graham C; Calder, Philip C

    2015-01-01

    The purpose of this article is to describe the structure, function and metabolism of fatty acids and lipids that are of particular importance in the context of parenteral nutrition. Lipids are a heterogeneous group of molecules that share the common property of hydrophobicity. Lipids range in structure from simple short hydrocarbon chains to more complex molecules, including triacylglycerols, phospholipids and sterols and their esters. Lipids within each class may differ structurally. Fatty acids are common components of complex lipids, and these differ according to chain length and the presence, number and position of double bonds in the hydrocarbon chain. Structural variation among complex lipids and among fatty acids gives rise to functional differences that result in different impacts upon metabolism and upon cell and tissue responses. Fatty acids and complex lipids exhibit a variety of structural variations that influence their metabolism and their functional effects. © 2015 S. Karger AG, Basel.

  1. The extraction of total lipids from parsley: Petroselinum crispum (mill. Nym. Ex. A.W. Hill seeds

    Directory of Open Access Journals (Sweden)

    Stanković Mihajlo Z.

    2004-01-01

    Full Text Available The kinetics of extraction of total lipids from ground parsley (Petroselinum crispum (Mill. Nym. ex. A.W. Hill seeds with a mixture of ethanol or methanol with non-polar organic solvents, chloroform, carbon tetrachloride, trichloroethylene and petroleum ether, at various temperatures were studied. The maceration technique with reflux was used. The kinetic parameters were determined in extraction kinetic equations, as well as the optimal operation conditions for total lipids extraction. The maximum total lipids yield under optimal conditions was 33.7 g per 100 g of dry parsley seeds. Nine lipid fractions of the total lipids were separated by thin layer chromatography among which were phospholipids, sterol, mono-, di- and triacylglycerol, free fatty acids and carbohydrates.

  2. VSWI Wetlands Advisory Layer

    Data.gov (United States)

    Vermont Center for Geographic Information — This dataset represents the DEC Wetlands Program's Advisory layer. This layer makes the most up-to-date, non-jurisdictional, wetlands mapping avaiable to the public...

  3. Lipid class and fatty acid composition of a little-known and rarely collected alga Exophyllum wentii Weber-van Bosse from Bali Island, Indonesia.

    Science.gov (United States)

    Illijas, Muhammad I; Indy, Jeane R; Yasui, Hajime; Itabashi, Yutaka

    2009-01-01

    The lipid class and fatty acid composition of a little-known and rarely collected alga Exophyllum wentii from Bali Island, Indonesia were determined for fresh and frozen-thawed samples using thin-layer chromatography, gas-liquid chromatography, and high-performance liquid chromatography. Glycoglycerolipids, which mainly consisted of mongalactosyldiacylglycerols (MGDG) and digalactosyldiacylglycerols (DGDG), were the predominant lipid components, accounting for 67% and 56% of the total polar lipid content in the fresh and frozen-thawed samples, respectively. Phospholipids, including phosphatidylcholines (PC) and phosphatidylglycerols (PG), were detected with lesser amounts in both samples (16-17% of the total polar lipid content). Free fatty acids (FFA), sterols and triacylglycerols (TAG) were also detected in minor quantities; however, the FFA content in the frozen-thawed sample increased to up to 20% of the total lipid content, suggesting that hydrolysis of the membrane lipids had occurred. A crude enzyme preparation from the alga showed activities for hydrolyzing the acyl groups of the phospholipids and glycoglycerolipids. Palmitic acid (16:0) and arachidonic acid (20:4n-6) were the major fatty acids in both the total lipid and in individual polar lipid classes as well as the dominant fatty acids released from the membrane lipids by enzymatic hydrolysis. The high level of 20:4n-6 (29%) in the total lipid and the presence of considerable amounts of PC (11% of the total polar lipid) and PG (6.2%) support classification of E. wentii into the Division Rhodophyta.

  4. Lipid and protein composition as driving force for multiple sclerosis

    Science.gov (United States)

    Beck, Roy; Shaharabani, Rona

    Physical models and experiments often reduce the number of components aiming to address the fundamental mechanisms. Nevertheless, the inherent heterogeneity is an essential ingredient in the biological context. We present our recent efforts to model and understand the development of multiple sclerosis (MS) from a biophysical perspective. Myelin sheath is a multilamellar complex of various lipids and proteins that surround axons and acts as an insulating layer for proper nerve conduction. In MS the myelin structure is disrupted impairing its function. Previous studies showed that MS is correlated with small lipid composition variation and reduction in the adhesive myelin basic protein. We found that such alterations result in pathological phase transition from a lamellar to inverted hexagonal that involve enhanced local curvature. Similar curvatures are also found in vivo in diseased myelin sheaths. Since the etiology and recovery pathways of MS are currently unclear, these findings delineate novel functional roles to dominant constituents in cytoplasmic myelin sheaths, shed new light on mechanisms disrupting lipid-protein complexes, and suggest new courses for diagnosis and treatment for MS.

  5. Serum lipids and lipoproteins in patients with psoriasis.

    Science.gov (United States)

    Taheri Sarvtin, Mehdi; Hedayati, Mohammad Taghi; Shokohi, Tahereh; HajHeydari, Zohreh

    2014-05-01

    Psoriasis is a common chronic and recurrent inflammatory skin disorder characterized by hyperproliferation of keratinocytes and infiltration of T cells, monocytes/macrophages and neutrophils into dermal and epidermal layers of the skin. The prevalence of cardiovascular disorders in these patients is remarkably higher compared to normal individuals, which seems to be associated with the hyperlipidemia. This study was designed and conducted to investigate the serum lipid profile in psoriatic patients and its association with the severity of disease. This case-control study was performed on 50 plaque-type psoriasis patients and 50 healthy individuals as control, matched for age and sex. Blood samples were collected after 14 h fasting. Serum triglyceride, cholesterol and lipoproteins were assayed using the standard kit (made by Pars Azmon Co. Iran). Certain parameters, including serum triglyceride, cholesterol, low density lipoprotein (LDL), and very low density lipoprotein (VLDL), were significantly higher in the case group compared to the controls (P lipoprotein (HDL) was significantly lower in the former (P < 0.001). In addition, there was a significant relationship between severity of psoriasis and serum lipid profile. The results have revealed the higher plasma level of lipids in psoriatic patients. This may elevate the risk of atherosclerosis, particularly cardiovascular disorders. Therefore, from the epidemiological point of view, screening psoriatic patients, particularly those with severe psoriasis, is recommended.

  6. Characterization and use of crystalline bacterial cell surface layers

    Science.gov (United States)

    Sleytr, Uwe B.; Sára, Margit; Pum, Dietmar; Schuster, Bernhard

    2001-10-01

    Crystalline bacterial cell surface layers (S-layers) are one of the most common outermost cell envelope components of prokaryotic organisms (archaea and bacteria). S-layers are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. S-layers as the most abundant of prokaryotic cellular proteins are appealing model systems for studying the structure, synthesis, genetics, assembly and function of proteinaceous supramolecular structures. The wealth of information existing on the general principle of S-layers have revealed a broad application potential. The most relevant features exploited in applied S-layer research are: (i) pores passing through S-layers show identical size and morphology and are in the range of ultrafiltration membranes; (ii) functional groups on the surface and in the pores are aligned in well-defined positions and orientations and accessible for chemical modifications and binding functional molecules in very precise fashion; (iii) isolated S-layer subunits from a variety of organisms are capable of recrystallizing as closed monolayers onto solid supports (e.g., metals, polymers, silicon wafers) at the air-water interface, on lipid films or onto the surface of liposomes; (iv) functional domains can be incorporated in S-layer proteins by genetic engineering. Thus, S-layer technologies particularly provide new approaches for biotechnology, biomimetics, molecular nanotechnology, nanopatterning of surfaces and formation of ordered arrays of metal clusters or nanoparticles as required for nanoelectronics.

  7. Cytoplasmic lipid bodies of human neutrophilic leukocytes

    International Nuclear Information System (INIS)

    Weller, P.F.; Ackerman, S.J.; Nicholson-Weller, A.; Dvorak, A.M.

    1989-01-01

    The morphology and function of cytoplasmic lipid bodies in human neutrophils were evaluated. By transmission electron microscopy, neutrophil lipid bodies were cytoplasmic inclusions, usually several microns in diameter, that occasionally coalesced to attain a diameter up to 7 microM. Neutrophil lipid bodies were not enveloped by membrane but were often surrounded by a more electron-dense shell at their periphery. Normal peripheral blood neutrophils contained an average of approximately one lipid body per cell. Lipid bodies appeared in greater numbers in neutrophils from inflammatory lesions. Perturbation of neutrophils during conventional methods of cell isolation and purification modestly increased lipid body numbers in neutrophils, whereas incubation of neutrophils with 1 microM oleic acid rapidly induced lipid body formation over 30 to 60 minutes. After granulocytes were incubated for 2 hours with 3H-fatty acids, including arachidonic, oleic, and palmitic acids, electron microscopic autoradiography demonstrated that lipid bodies represented the predominant intracellular sites of localization of each of the three 3H-fatty acids. There was lesser labeling noted in the perinuclear cisterna, but not in cell membranes. Virtually all of each of the three 3H-fatty acids incorporated by the neutrophils were esterified into chromatographically resolved classes of neutral lipids or phospholipids. These findings indicate that cytoplasmic lipid bodies are more prominent in neutrophils in vivo engaged in inflammatory responses and that these organelles in human neutrophils function as sites of deposition of esterified, incorporated fatty acids

  8. Double layers in space

    International Nuclear Information System (INIS)

    Carlqvist, P.

    1982-07-01

    For more than a decade it has been realised that electrostatic double layers are likely to occur in space. We briefly discuss the theoretical background of such double layers. Most of the paper is devoted to an account of the observational evidence for double layers in the ionosphere and magnetosphere of the Earth. Several different experiments are reviewed including rocket and satellite measurements and ground based observations. It is concluded that the observational evidence for double layers in space is very strong. The experimental results indicate that double layers with widely different properties may exist in space. (Author)

  9. Double layers in space

    International Nuclear Information System (INIS)

    Carlqvist, P.

    1982-01-01

    For more than a decade it has been realised that electrostatic double layers are likely to occur in space. The author briefly discusses the theoretical background of such double layers. Most of the paper is devoted to an account of the observational evidence for double layers in the ionosphere and magnetosphere of the Earth. Several different experiments are reviewed including rocket and satellite measurements and ground based observations. It is concluded that the observational evidence for double layers in space is very strong. The experimental results indicate that double layers with widely different properties may exist in space. (Auth.)

  10. Interaction of S-layer proteins of Lactobacillus kefir with model membranes and cells.

    Science.gov (United States)

    Hollmann, Axel; Delfederico, Lucrecia; Santos, Nuno C; Disalvo, E Anibal; Semorile, Liliana

    2018-06-01

    In previous works, it was shown that S-layer proteins from Lactobacillus kefir were able to recrystallize and stabilize liposomes, this feature reveling a great potential for developing liposomal-based carriers. Despite previous studies on this subject are important milestones, a number of questions remain unanswered. In this context, the feasibility of S-layer proteins as a biomaterial for drug delivery was evaluated in this work. First, S-layer proteins were fully characterized by electron microscopy, 2D-electrophoresis, and anionic exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). Afterward, interactions of S-layer proteins with model lipid membranes were evaluated, showing that proteins adsorb to the lipid surface following a non-fickean or anomalous diffusion, when positively charged lipid were employed, suggesting that electrostatic interaction is a key factor in the recrystallization process on these proteins. Finally, the interaction of S-layer coated liposomes with Caco-2 cell line was assessed: First, cytotoxicity of formulations was tested showing no cytotoxic effects in S-layer coated vesicles. Second, by flow cytometry, it was observed an increased ability to transfer cargo molecules into Caco-2 cells from S-layer coated liposomes in comparison to control ones. All data put together, supports the idea that a combination of adhesive properties of S-layer proteins concomitant with higher stability of S-layer coated liposomes represents an exciting starting point in the development of new drug carriers.

  11. Lipid resuscitation in acute poisoning

    DEFF Research Database (Denmark)

    Hoegberg, Lotte C G; Gosselin, Sophie

    2017-01-01

    PURPOSE OF REVIEW: The decision to provide intravenous lipid emulsion (ILE) therapy as a treatment modality for the reversal of various drug toxicity was discovered in the last decade. Numerous publications, in both humans and animals attest to its clinical use, but current supporting evidence...... is inconsistent. RECENT FINDINGS: A recent systematic review reported evidence for benefit of ILE in bupivacaine toxicity. Human randomized trials, large observational studies as well as animal models of orogastric poisoning failed to report a clear benefit of ILE for nonlocal anesthetics poisoning. SUMMARY: ILE...

  12. Cholesterol Perturbs Lipid Bilayers Nonuniversally

    International Nuclear Information System (INIS)

    Pan Jianjun; Mills, Thalia T.; Tristram-Nagle, Stephanie; Nagle, John F.

    2008-01-01

    Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K C , the thickness D HH , and the orientational order parameter S xray of lipid bilayers. We find that the effects are different for at least three classes of phospholipids characterized by different numbers of saturated hydrocarbon chains. Most strikingly, cholesterol strongly increases K C when both chains of the phospholipid are fully saturated but not at all when there are two monounsaturated chains

  13. New Lipids From Cultured Archaea and Environmental Samples

    Science.gov (United States)

    Summons, R. E.; Meyer-Dombard, D. R.; Bradley, A. S.; Hebting, Y.; Jahnke, L. L.; Embaye, T.; Orphan, V. J.

    2006-12-01

    The intact polar lipids of Archaea comprise cores with isoprenoid hydrocarbon chains with 20, 25 or 40 carbon atoms linked through ether bonds to glycerol. These cores can take the form of diethers or membrane- spanning tetraethers. Together with their wide array of polar head groups, these compounds are structurally diverse and potentially very useful as taxonomic markers for making assessments of microbial diversity independently of genomic approaches. Furthermore, the recalcitrant hydrocarbon chains of these lipids are the only really effective means to identify the presence of Archaea in ancient sedimentary environments. The advent of new LC-MS methods has enabled ready identification and quantification of intact polar lipids in cultures and environmental samples based on comparisons with appropriate standard compounds [1, 2]. However, these LC-MS analyses of intact lipids have also revealed the presence of additional compounds and it is likely that many of these represent chemical structures that are new to science. Elucidating these structures is a major analytical challenge because, generally, only minute amounts of material available for chemical characterization. In order to study these potentially new structures, one layer of information can be obtained by chemical degradation to remove and identify the polar head groups [2]. Cleavage of the ether bonds releases the hydrocarbon chains for their further characterization. One class of core lipids, the 3-hydroxyarchaeols, escaped detection for many years because strong acid treatments in the analysis protocols had destroyed hydroxyl-containing isoprenoid chains. We have now re-examined the lipids of a thermophilic methanogen, M. thermolithotrophicus, using mild procedures and avoiding strong acids. As well as the known compounds archaeol, sn-2-hydroxyarchaeol and sn-3-hydroxyarchaeol, we encountered dihydroxyarchaeol. Moreover, the hydroxylated archaeols were found to exist as a very complex mixture of

  14. Surface activity, lipid profiles and their implications in cervical cancer.

    Directory of Open Access Journals (Sweden)

    Preetha A

    2005-01-01

    Full Text Available Background: The profiles of lipids in normal and cancerous tissues may differ revealing information about cancer development and progression. Lipids being surface active, changes in lipid profiles can manifest as altered surface activity profiles. Langmuir monolayers offer a convenient model for evaluating surface activity of biological membranes. Aims: The aims of this study were to quantify phospholipids and their effects on surface activity of normal and cancerous human cervical tissues as well as to evaluate the role of phosphatidylcholine (PC and sphingomyelin (SM in cervical cancer using Langmuir monolayers. Methods and Materials: Lipid quantification was done using thin layer chromatography and phosphorus assay. Surface activity was evaluated using Langmuir monolayers. Monolayers were formed on the surface of deionized water by spreading tissue organic phase corresponding to 1 mg of tissue and studying their surface pressure-area isotherms at body temperature. The PC and SM contents of cancerous human cervical tissues were higher than those of the normal human cervical tissues. Role of PC and SM were evaluated by adding varying amounts of these lipids to normal cervical pooled organic phase. Statistical analysis: Student′s t-test (p < 0.05 and one-way analysis of variance (ANOVA was used. Results: Our results reveals that the phosphatidylglycerol level in cancerous cervical tissue was nearly five folds higher than that in normal cervical tissue. Also PC and sphingomyelin SM were found to be the major phospholipid components in cancerous and normal cervical tissues respectively. The addition of either 1.5 µg DPPC or 0.5 µg SM /mg of tissue to the normal organic phase changed its surface activity profile to that of the cancerous tissues. Statistically significant surface activity parameters showed that PC and SM have remarkable roles in shifting the normal cervical lipophilic surface activity towards that of cancerous lipophilic

  15. Molecular imaging of lipids in cells and tissues

    Science.gov (United States)

    Borner, Katrin; Malmberg, Per; Mansson, Jan-Eric; Nygren, Hakan

    2007-02-01

    The distribution pattern of lipid species in biological tissues was analyzed with imaging mass spectrometry (TOF-SIMS; time-of-flight secondary ion mass spectrometry). The first application shows distribution of a glycosphingolipid, the galactosylceramide-sulfate (sulfatide) with different hydrocarbon chain lengths and the fatty acids palmitate and oleate in rat cerebellum. Sulfatides were seen localized in regions suggested as paranodal areas of rat cerebellar white matter as well as in the granular layer, with highest concentrations at the borders of the white matter. Different distribution patterns could be shown for the fatty acid C16:0 palmitate and C18:1 oleate in rat cerebellum, which seem to origin partly from the hydrocarbon chains of phosphatidylcholine. Results were shown for two different tissue preparation methods, which were plunge-freezing and cryostat sectioning as well as high-pressure freezing, freeze-fracturing and freeze-drying. The second application shows TOF-SIMS analysis on a biological trial of choleratoxin treatment in mouse intestine. The effect of cholera toxin on lipids in the intestinal epithelium was shown by comparing control and cholera toxin treated mouse intestine samples. A significant increase of the cholesterol concentration was seen after treatment. Cholesterol was mainly localized to the brush border of enterocytes of the intestinal villi, which could be explained by the presence of cholesterol-rich lipid rafts present on the microvilli or by relations to cholesterol uptake. After cholera toxin exposure, cholesterol was seen increased in the nuclei of enterocytes and apparently in the interstitium of the villi. We find that imaging TOF-SIMS is a powerful tool for studies of lipid distributions in cells and tissues, enabling the elucidation of their role in cell function and biology.

  16. Lipid phase control of DNA delivery

    Energy Technology Data Exchange (ETDEWEB)

    Koynova, Rumiana; Wang, Li; Tarahovsky, Yury; MacDonald, Robert C. (NWU)

    2010-01-18

    Cationic lipids form nanoscale complexes (lipoplexes) with polyanionic DNA and can be utilized to deliver DNA to cells for transfection. Here we report the correlation between delivery efficiency of these DNA carriers and the mesomorphic phases they form when interacting with anionic membrane lipids. Specifically, formulations that are particularly effective DNA carriers form phases of highest negative interfacial curvature when mixed with anionic lipids, whereas less effective formulations form phases of lower curvature. Structural evolution of the carrier lipid/DNA complexes upon interaction with cellular lipids is hence suggested as a controlling factor in lipid-mediated DNA delivery. A strategy for optimizing lipofection is deduced. The behavior of a highly effective lipoplex formulation, DOTAP/DOPE, is found to conform to this 'efficiency formula'.

  17. Crossover of two power laws in the anomalous diffusion of a two lipid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Bakalis, Evangelos, E-mail: ebakalis@gmail.com, E-mail: francesco.zerbetto@unibo.it; Höfinger, Siegfried; Zerbetto, Francesco, E-mail: ebakalis@gmail.com, E-mail: francesco.zerbetto@unibo.it [Dipartimento di Chimica “G. Ciamician”, Universita’ di Bologna, Via F. Selmi 2, 40126 Bologna (Italy); Venturini, Alessandro [Institute for the Organic Synthesis and Photoreactivity, National Research Council of Italy, Via Gobetti 101, 40129 Bologna (Italy)

    2015-06-07

    Molecular dynamics simulations of a bi-layer membrane made by the same number of 1-palmitoyl-2-oleoyl-glycero-3-phospho-ethanolamine and palmitoyl-oleoyl phosphatidylserine lipids reveal sub-diffusional motion, which presents a crossover between two different power laws. Fractional Brownian motion is the stochastic mechanism that governs the motion in both regimes. The location of the crossover point is justified with simple geometrical arguments and is due to the activation of the mechanism of circumrotation of lipids about each other.

  18. Crossover of two power laws in the anomalous diffusion of a two lipid membrane.

    Science.gov (United States)

    Bakalis, Evangelos; Höfinger, Siegfried; Venturini, Alessandro; Zerbetto, Francesco

    2015-06-07

    Molecular dynamics simulations of a bi-layer membrane made by the same number of 1-palmitoyl-2-oleoyl-glycero-3-phospho-ethanolamine and palmitoyl-oleoyl phosphatidylserine lipids reveal sub-diffusional motion, which presents a crossover between two different power laws. Fractional Brownian motion is the stochastic mechanism that governs the motion in both regimes. The location of the crossover point is justified with simple geometrical arguments and is due to the activation of the mechanism of circumrotation of lipids about each other.

  19. Targeting Lipid Metabolic Reprogramming as Anticancer Therapeutics

    OpenAIRE

    Cha, Ji-Young; Lee, Ho-Jae

    2016-01-01

    Cancer cells rewire their metabolism to satisfy the demands of growth and survival, and this metabolic reprogramming has been recognized as an emerging hallmark of cancer. Lipid metabolism is pivotal in cellular process that converts nutrients into energy, building blocks for membrane biogenesis and the generation of signaling molecules. Accumulating evidence suggests that cancer cells show alterations in different aspects of lipid metabolism. The changes in lipid metabolism of cancer cells c...

  20. Lipids as organizers of cell membranes.

    Science.gov (United States)

    Kornmann, Benoît; Roux, Aurélien

    2012-08-01

    The 105th Boehringer Ingelheim Fonds International Titisee Conference 'Lipids as Organizers of Cell Membranes' took place in March 2012, in Germany. Kai Simons and Gisou Van der Goot gathered cell biologists and biophysicists to discuss the interplay between lipids and proteins in biological membranes, with an emphasis on how technological advances could help fill the gap in our understanding of the lipid part of the membrane.

  1. Changes of lipids in irradiated chickens

    International Nuclear Information System (INIS)

    Moersel, J.T.; Wende, I.; Schwarz, K.

    1991-01-01

    Chickens were irradiated in a 6 deg Co gamma irradiation source. The irradiation has been done to reduce or eliminate Salmonella. The experiments were done to test this decontamination method of chickens if changes of lipids take place. It was to be seen, that peroxidation of lipids was more rapidly as in control. The time of storage of irradiated chickens has to be shorter because of changes in lipids. After irradiation the chickens had trade quality. (orig.) [de

  2. Effects of atmospheric pollutants on lipids

    International Nuclear Information System (INIS)

    Howton, D.R.

    1976-01-01

    Studies on effects of atmospheric pollutants on lipids emphasized effects of nitrogen dioxide on olefinic centers of alveolar fluid surfactant lipids. The finding that NO 2 attacks α-tocopherol much more avidly than olefinic fatty esters indicates that the autoxidation enhancing effects of this atmospheric pollutant may be greatly magnified by destruction of native antioxidants that normally suppress the extensiveness of such lipid oxidation

  3. Lacrimal hypofunction as a new mechanism of dry eye in visual display terminal users.

    Directory of Open Access Journals (Sweden)

    Shigeru Nakamura

    Full Text Available BACKGROUND: Dry eye has shown a marked increase due to visual display terminal (VDT use. It remains unclear whether reduced blinking while focusing can have a direct deleterious impact on the lacrimal gland function. To address this issue that potentially affects the life quality, we conducted a large-scale epidemiological study of VDT users and an animal study. METHODOLOGY/PRINCIPAL FINDINGS: Cross sectional survey carried out in Japan. A total of 1025 office workers who use VDT were enrolled. The association between VDT work duration and changes in tear film status, precorneal tear stability, lipid layer status and tear secretion were analyzed. For the animal model study, the rat VDT user model, placing rats onto a balance swing in combination with exposure to an evaporative environment was used to analyze lacrimal gland function. There was no positive relationship between VDT working duration and change in tear film stability and lipid layer status. The odds ratio for decrease in Schirmer score, index of tear secretion, were significantly increased with VDT working year (P = 0.012 and time (P = 0.005. The rat VDT user model, showed chronic reduction of tear secretion and was accompanied by an impairment of the lacrimal gland function and morphology. This dysfunction was recovered when rats were moved to resting conditions without the swing. CONCLUSIONS/SIGNIFICANCE: These data suggest that lacrimal gland hypofunction is associated with VDT use and may be a critical mechanism for VDT-associated dry eye. We believe this to be the first mechanistic link to the pathogenesis of dry eye in office workers.

  4. Steroidal Compounds in Commercial Parenteral Lipid Emulsions

    Science.gov (United States)

    Xu, Zhidong; Harvey, Kevin A.; Pavlina, Thomas; Dutot, Guy; Hise, Mary; Zaloga, Gary P.; Siddiqui, Rafat A.

    2012-01-01

    Parenteral nutrition lipid emulsions made from various plant oils contain steroidal compounds, called phytosterols. During parenteral administration of lipid emulsions, phytosterols can reach levels in the blood that are many fold higher than during enteral administration. The elevated phytosterol levels have been associated with the development of liver dysfunction and the rare development of liver failure. There is limited information available in the literature related to phytosterol concentrations in lipid emulsions. The objective of the current study was to validate an assay for steroidal compounds found in lipid emulsions and to compare their concentrations in the most commonly used parenteral nutrition lipid emulsions: Liposyn® II, Liposyn® III, Lipofundin® MCT, Lipofundin® N, Structolipid®, Intralipid®, Ivelip® and ClinOleic®. Our data demonstrates that concentrations of the various steroidal compounds varied greatly between the eight lipid emulsions, with the olive oil-based lipid emulsion containing the lowest levels of phytosterols and cholesterol, and the highest concentration of squalene. The clinical impression of greater incidences of liver dysfunction with soybean versus MCT/LCT and olive/soy lipid emulsions may be reflective of the levels of phytosterols in these emulsions. This information may help guide future studies and clinical care of patients with lipid emulsion-associated liver dysfunction. PMID:23016123

  5. Lipid Metabolism, Apoptosis and Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Chunfa Huang

    2015-01-01

    Full Text Available Lipid metabolism is regulated by multiple signaling pathways, and generates a variety of bioactive lipid molecules. These bioactive lipid molecules known as signaling molecules, such as fatty acid, eicosanoids, diacylglycerol, phosphatidic acid, lysophophatidic acid, ceramide, sphingosine, sphingosine-1-phosphate, phosphatidylinositol-3 phosphate, and cholesterol, are involved in the activation or regulation of different signaling pathways. Lipid metabolism participates in the regulation of many cellular processes such as cell growth, proliferation, differentiation, survival, apoptosis, inflammation, motility, membrane homeostasis, chemotherapy response, and drug resistance. Bioactive lipid molecules promote apoptosis via the intrinsic pathway by modulating mitochondrial membrane permeability and activating different enzymes including caspases. In this review, we discuss recent data in the fields of lipid metabolism, lipid-mediated apoptosis, and cancer therapy. In conclusion, understanding the underlying molecular mechanism of lipid metabolism and the function of different lipid molecules could provide the basis for cancer cell death rationale, discover novel and potential targets, and develop new anticancer drugs for cancer therapy.

  6. Metabolism of lipids in Epidermophyton floccosum

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, A; Khuller, G K [Post-Graduate Inst. of Medical Education and Research, Chandigarh (India)

    1981-03-01

    Metabolism of major lipids in E. floccosum was studied with /sup 14/C-acetate as a precursor. Among the phosphatides, phosphatidylcholine exhibited the maximum rate of synthesis and degradation, followed by phosphatidylethanolamine and phosphatidylserine. These phospholipids appear to exist in two pools, one metabolically more active than the other. In neutral lipids, maximum uptake was observed in triglycerides, followed by free fatty acids, diglycerides and monoglycerides. However, on chase of the labelled lipids, a continuous synthesis of all neutral lipid fractions was observed suggesting a recycling of the labelled carbon.

  7. Steroidal compounds in commercial parenteral lipid emulsions.

    Science.gov (United States)

    Xu, Zhidong; Harvey, Kevin A; Pavlina, Thomas; Dutot, Guy; Hise, Mary; Zaloga, Gary P; Siddiqui, Rafat A

    2012-08-01

    Parenteral nutrition lipid emulsions made from various plant oils contain steroidal compounds, called phytosterols. During parenteral administration of lipid emulsions, phytosterols can reach levels in the blood that are many fold higher than during enteral administration. The elevated phytosterol levels have been associated with the development of liver dysfunction and the rare development of liver failure. There is limited information available in the literature related to phytosterol concentrations in lipid emulsions. The objective of the current study was to validate an assay for steroidal compounds found in lipid emulsions and to compare their concentrations in the most commonly used parenteral nutrition lipid emulsions: Liposyn(®) II, Liposyn(®) III, Lipofundin(®) MCT, Lipofundin(®) N, Structolipid(®), Intralipid(®), Ivelip(®) and ClinOleic(®). Our data demonstrates that concentrations of the various steroidal compounds varied greatly between the eight lipid emulsions, with the olive oil-based lipid emulsion containing the lowest levels of phytosterols and cholesterol, and the highest concentration of squalene. The clinical impression of greater incidences of liver dysfunction with soybean versus MCT/LCT and olive/soy lipid emulsions may be reflective of the levels of phytosterols in these emulsions. This information may help guide future studies and clinical care of patients with lipid emulsion-associated liver dysfunction.

  8. Steroidal Compounds in Commercial Parenteral Lipid Emulsions

    Directory of Open Access Journals (Sweden)

    Rafat A. Siddiqui

    2012-08-01

    Full Text Available Parenteral nutrition lipid emulsions made from various plant oils contain steroidal compounds, called phytosterols. During parenteral administration of lipid emulsions, phytosterols can reach levels in the blood that are many fold higher than during enteral administration. The elevated phytosterol levels have been associated with the development of liver dysfunction and the rare development of liver failure. There is limited information available in the literature related to phytosterol concentrations in lipid emulsions. The objective of the current study was to validate an assay for steroidal compounds found in lipid emulsions and to compare their concentrations in the most commonly used parenteral nutrition lipid emulsions: Liposyn® II, Liposyn® III, Lipofundin® MCT, Lipofundin® N, Structolipid®, Intralipid®, Ivelip® and ClinOleic®. Our data demonstrates that concentrations of the various steroidal compounds varied greatly between the eight lipid emulsions, with the olive oil-based lipid emulsion containing the lowest levels of phytosterols and cholesterol, and the highest concentration of squalene. The clinical impression of greater incidences of liver dysfunction with soybean versus MCT/LCT and olive/soy lipid emulsions may be reflective of the levels of phytosterols in these emulsions. This information may help guide future studies and clinical care of patients with lipid emulsion-associated liver dysfunction.

  9. Jabuticaba [Pliniajaboticaba (Vell.) Berg] skins decrease lipid ...

    African Journals Online (AJOL)

    SAM

    2014-03-12

    density lipoprotein cholesterol; MDA, malondialdehyde ... rats, and quantification and characterization of its .... Moisture and lipid content were determined using the methods ... acids and flavonoids were identified, presenting the.

  10. Electrodiffusion of lipids on membrane surfaces.

    Science.gov (United States)

    Zhou, Y C

    2012-05-28

    Lateral translocation of lipids and proteins is a universal process on membrane surfaces. Local aggregation or organization of lipids and proteins can be induced when the random lateral motion is mediated by the electrostatic interactions and membrane curvature. Although the lateral diffusion rates of lipids on membranes of various compositions are measured and the electrostatic free energies of predetermined protein-membrane-lipid systems can be computed, the process of the aggregation and the evolution to the electrostatically favorable states remain largely undetermined. Here we propose an electrodiffusion model, based on the variational principle of the free energy functional, for the self-consistent lateral drift-diffusion of multiple species of charged lipids on membrane surfaces. Finite sizes of lipids are modeled to enforce the geometrical constraint of the lipid concentration on membrane surfaces. A surface finite element method is developed to appropriate the Laplace-Beltrami operators in the partial differential equations of the model. Our model properly describes the saturation of lipids on membrane surfaces, and correctly predicts that the MARCKS peptide can consistently sequester three multivalent phosphatidylinositol 4,5-bisphosphate lipids through its basic amino acid residues, regardless of a wide range of the percentage of monovalent phosphatidylserine in the membrane.

  11. Biologic activity of porphyromonas endodontalis complex lipids.

    Science.gov (United States)

    Mirucki, Christopher S; Abedi, Mehran; Jiang, Jin; Zhu, Qiang; Wang, Yu-Hsiung; Safavi, Kamran E; Clark, Robert B; Nichols, Frank C

    2014-09-01

    Periapical infections secondary to pulpal necrosis are associated with bacterial contamination of the pulp. Porphyromonas endodontalis, a gram-negative organism, is considered to be a pulpal pathogen. P. gingivalis is phylogenetically related to P. endodontalis and synthesizes several classes of novel complex lipids that possess biological activity, including the capacity to promote osteoclastogenesis and osteoclast activation. The purpose of this study was to extract and characterize constituent lipids of P. endodontalis and evaluate their capacity to promote proinflammatory secretory responses in the macrophage cell line, RAW 264.7, as well as their capacity to promote osteoclastogenesis and inhibit osteoblast activity. Constituent lipids of both organisms were fractionated by high-performance liquid chromatography and were structurally characterized using electrospray mass spectrometry or electrospray-mass spectrometry/mass spectrometry. The virulence potential of P. endodontalis lipids was then compared with known biologically active lipids isolated from P. gingivalis. P. endodontalis total lipids were shown to promote tumor necrosis factor alpha secretion from RAW 264.7 cells, and the serine lipid fraction appeared to account for the majority of this effect. P. endodontalis lipid preparations also increased osteoclast formation from RAW 264.7 cells, but osteoblast differentiation in culture was inhibited and appeared to be dependent on Toll-like receptor 2 expression. These effects underscore the importance of P. endodontalis lipids in promoting inflammatory and bone cell activation processes that could lead to periapical pathology. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Lipid sac area as a proxy for individual lipid content of arctic calanoid copepods

    OpenAIRE

    Vogedes, Daniel; Varpe, ?ystein; S?reide, Janne E.; Graeve, Martin; Berge, J?rgen; Falk-Petersen, Stig

    2010-01-01

    We present an accurate, fast, simple and non-destructive photographic method to estimate wax ester and lipid content in single individuals of the calanoid copepod genus Calanus and test this method against gas-chromatographic lipid measurements.

  13. Localizing genes to cerebellar layers by classifying ISH images.

    Directory of Open Access Journals (Sweden)

    Lior Kirsch

    Full Text Available Gene expression controls how the brain develops and functions. Understanding control processes in the brain is particularly hard since they involve numerous types of neurons and glia, and very little is known about which genes are expressed in which cells and brain layers. Here we describe an approach to detect genes whose expression is primarily localized to a specific brain layer and apply it to the mouse cerebellum. We learn typical spatial patterns of expression from a few markers that are known to be localized to specific layers, and use these patterns to predict localization for new genes. We analyze images of in-situ hybridization (ISH experiments, which we represent using histograms of local binary patterns (LBP and train image classifiers and gene classifiers for four layers of the cerebellum: the Purkinje, granular, molecular and white matter layer. On held-out data, the layer classifiers achieve accuracy above 94% (AUC by representing each image at multiple scales and by combining multiple image scores into a single gene-level decision. When applied to the full mouse genome, the classifiers predict specific layer localization for hundreds of new genes in the Purkinje and granular layers. Many genes localized to the Purkinje layer are likely to be expressed in astrocytes, and many others are involved in lipid metabolism, possibly due to the unusual size of Purkinje cells.

  14. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  15. Distribution of neutral lipids in the lipid droplet core

    DEFF Research Database (Denmark)

    Chaban, Vitaly V; Khandelia, Himanshu

    2014-01-01

    Cholesteryl esters (CEs) are a form of cholesterol (CHOL) storage in the living cells, as opposed to free CHOL. CEs are major constituents of low density lipoprotein particles. Therefore, CEs are implicated in provoking atherosclerosis. Arranged into cytoplasmic lipid droplets (LDs), CEs are stored...... intracellularly. They can also be transported extracellularly by means of lipoproteins. In this work, large-scale molecular dynamics (MD) simulations are used to characterize the molecular structure of LDs containing various fractions (10-50 mol %) of cholesteryl oleate (CO) with respect to triolein (TO) fraction...... the phospholipid interface, resulting from the structuring of hydrophilic groups. This structuring slowly decays in the direction toward the LD center of mass. No sorting of TO and CO is detected, irrespective of the molar fractions simulated. The distribution of CO within the LDs is significant in determining...

  16. Coupling Fluid and Solute Dynamics Within the Ocular Surface Tear Film: A Modelling Study of Black Line Osmolarity

    KAUST Repository

    Zubkov, V. S.; Breward, C. J. W.; Gaffney, E. A.

    2012-01-01

    in these regions. More generally, a heterogeneous distribution of solute concentration is predicted across the ocular surface, indicating that measurements of lower meniscus osmolarity are not globally representative, especially in the presence of dry eye. Vertical

  17. Assessment of Corneal and Tear Film Parameters in Rheumatoid Arthritis Patients Using Anterior Segment Spectral Domain Optical Coherence Tomography.

    Science.gov (United States)

    El-Fayoumi, Dina; Youssef, Maha Mohamed; Khafagy, Mohamed Mahmoud; Badr El Dine, Nashwa; Gaber, Wafaa

    2018-01-01

    To study the corneal changes in rheumatoid arthritis (RA) patients in vivo, using spectral domain anterior segment optical coherence tomography (AS-OCT). A case-control study was done on 43 RA patients and 40 controls. The disease activity score (DAS28-ESR) was calculated and all participants had lower tear meniscus, corneal thickness, and epithelial thickness evaluation using AS-OCT. The lower tear meniscus height (LTMH) and the lower tear meniscus area (LTMA) were significantly lower in the RA patients than in controls (p < 0.001). RA patients also had a significantly thinner central corneal thickness (p = 0.02) and their epithelium was found to be thinner in the superotemporal peripheral sector. The LTMH and LTMA are significantly reduced in RA patients, despite the absence of clinical diagnosis of dry eye. RA patients have thinner corneal thickness and epithelial thickness than controls, which did not correlate with either disease duration or activity.

  18. Human tear film and meibum. Very long chain wax esters and (O-acyl)-omega-hydroxy fatty acids of meibum

    OpenAIRE

    Butovich, Igor A.; Wojtowicz, Jadwiga C.; Molai, Mike

    2009-01-01

    Human meibum was targetly analyzed for the presence of intact wax esters (WEs) and related compounds by means of reverse-phase HPLC in combination with ion trap mass spectrometry. The major detected WEs were based on C18:n (n = 1–4) unsaturated FAs ranking in the following order of abundance: C18:1>C18:2>C18:3>C18:4. The major fatty alcohols (FAls) found in WE were of saturated nature and varied from C18:0 to C28:0. The three most abundant species were C18:1-FA esters of C24:0, C25:0, and C26...

  19. Assessment of tear film osmolarity using the TearLab™ osmometer in normal dogs and dogs with keratoconjunctivitis sicca.

    Science.gov (United States)

    Sebbag, Lionel; Park, Shin Ae; Kass, Philip H; Maggs, David J; Attar, Mayssa; Murphy, Christopher J

    2017-07-01

    To evaluate repeatability and reproducibility of tear osmolarity measured using the TearLab ™ osmometer in normal dogs and to assess its diagnostic potential in dogs with keratoconjunctivitis sicca (KCS). Beagle dogs; six normal and five with KCS. Tear osmolarity and Schirmer tear test-1 (STT-1) values were obtained at various times. Normal dogs were assessed for diurnal variation and repeatability and reproducibility of measurements. Dogs with KCS were evaluated before and after 5 months' topical twice-daily therapy with 2% cyclosporine. Mean ± SD tear osmolarity (mOsm/L) was significantly higher in normal dogs (337.4 ± 16.2) than in dogs with KCS before therapy (306.2 ± 18.0; P dogs, tear osmolarity readings were stable during the daytime (P = 0.99). Repeated measurements revealed high variability and typically poor-to-moderate repeatability and reproducibility, although this was improved by taking three successive measurements at each session. Considering combined data from all dogs, a positive correlation existed between STT-1 and tear osmolarity measurements (Pearson's correlation test, P = 0.04, r = 0.62). Canine tear osmolarity as determined by TearLab ™ osmometer was variable, required multiple readings to be informative, and differed from values reported for humans. Dogs with KCS had a lower tear osmolarity than did normal dogs, and this increased following cyclosporine therapy. © 2016 American College of Veterinary Ophthalmologists.

  20. A double layer review

    International Nuclear Information System (INIS)

    Block, L.P.

    1977-06-01

    A review of the main results on electrostatic double layers (sometimes called space charge layers or sheaths) obtained from theory, and laboratory and space experiments up to the spring of 1977 is given. By means of barium jets and satellite probes, double layers have now been found at the altitudes, earlier predicted theoretically. The general potential distribution above the auroral zone, suggested by inverted V-events and electric field reversals, is corroborated. (author)

  1. Two layer powder pressing

    International Nuclear Information System (INIS)

    Schreiner, H.

    1979-01-01

    First, significance and advantages of sintered materials consisting of two layers are pointed out. By means of the two layer powder pressing technique metal powders are formed resulting in compacts with high accuracy of shape and mass. Attributes of basic powders, different filling methods and pressing techniques are discussed. The described technique is supposed to find further applications in the field of two layer compacts in the near future

  2. Economical Atomic Layer Deposition

    Science.gov (United States)

    Wyman, Richard; Davis, Robert; Linford, Matthew

    2010-10-01

    Atomic Layer Deposition is a self limiting deposition process that can produce films at a user specified height. At BYU we have designed a low cost and automated atomic layer deposition system. We have used the system to deposit silicon dioxide at room temperature using silicon tetrachloride and tetramethyl orthosilicate. Basics of atomic layer deposition, the system set up, automation techniques and our system's characterization are discussed.

  3. Stable Boundary Layer Issues

    OpenAIRE

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer ...

  4. Natural lipids in nanostructured lipid carriers and its cytotoxicity

    Science.gov (United States)

    Lima, Paula A.; Rampazo, Caroline A. D.; Costa, Amanda F.; Rodrigues, Tiago; Watashi, Carolina M.; Durán, Nelson

    2017-06-01

    Nanostructured lipid carriers (NLCs) are active carrier systems which modulate the sustained release of actives and protect unstable compounds against degradation. NLCs can also protect skin from sun light, due to its particulates nature, which gives them intrinsic scattering properties. In this work, we present the preparation of NLCs using natural lipids and its cytotoxicity profile. It was used a vegetal butter with melting point (m.p.) ~32-40°C, an animal wax (m.p. 35-40°C) and a vegetal oil (boiling point ~120-150°C). NLCs were prepared by hot high pressure homogenization method and particles were characterized by average size (Zave), polydispersity index (PDI) and zeta potential (PZ) (Fig.1). The thermal behavior of the NLCs was studied using Differential Scanning Calorimetry (DSC). All the formulations were followed up for 60 days in order to evaluate their stability. NLCs exhibited a Zave around 150-200 nm, PDI less than 0.2 and PZ varying from -25 to -40 mV. The m.p. for the lyophilized NLCs was about 40-56°C. Cytotoxicity of the formulations were evaluated for human keratinocytes (HaCaT) and melanocytes (Melan-A) in the exponential growth phase. Cell viability was used as indicator of cytotoxicity and determined after 4 days of culture by MTT assay. It was found that the NLC formulations were not toxic against HaCaT and Melan-A cells. Results showed that the NLCs produced are potential carriers for nanocosmetics and sunscreen products.

  5. Lipid polymorphism and the functional roles of lipids in biological membranes

    NARCIS (Netherlands)

    Cullis, P.R.; Kruijff, B. de

    1979-01-01

    The reasons for the great variety of lipids found in biological membranes, and the relations between lipid composition and membrane function pose major unsolved problems in membrane biology. Perhaps the only major functional role of lipids which may be regarded as firmly established involves the

  6. Layered plasma polymer composite membranes

    Science.gov (United States)

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  7. Formation of double layers

    International Nuclear Information System (INIS)

    Leung, P.; Wong, A.Y.; Quon, B.H.

    1981-01-01

    Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

  8. Electroless atomic layer deposition

    Science.gov (United States)

    Robinson, David Bruce; Cappillino, Patrick J.; Sheridan, Leah B.; Stickney, John L.; Benson, David M.

    2017-10-31

    A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.

  9. Fluorescent lipid probes : some properties and applications (a review)

    NARCIS (Netherlands)

    Maier, O; Oberle, [No Value; Hoekstra, D

    Odd as it may seem, experimental challenges in lipid research are often hampered by the simplicity of the lipid structure. Since, as in protein research. mutants or overexpression of lipids are not realistic, a considerable amount of lipid research relies on the use Of tagged lipid analogues.

  10. Molecular Interaction of a New Antibacterial Polymer with a Supported Lipid Bilayer Measured by an in situ Label-Free Optical Technique

    Directory of Open Access Journals (Sweden)

    Robert Horvath

    2013-05-01

    Full Text Available The interaction of the antibacterial polymer–branched poly(ethylene imine substituted with quaternary ammonium groups, PEO and alkyl chains, PEI25QI5J5A815–with a solid supported lipid bilayer was investigated using surface sensitive optical waveguide spectroscopy. The analysis of the optogeometrical parameters was extended developing a new composite layer model in which the structural and optical anisotropy of the molecular layers was taken into consideration. Following in situ the change of optical birefringence we were able to determine the composition of the lipid/polymer surface layer as well as the displacement of lipid bilayer by the antibacterial polymer without using additional labeling. Comparative assessment of the data of layer thickness and optical anisotropy helps to reveal the molecular mechanism of antibacterial effect of the polymer investigated.

  11. Atomistic Monte Carlo simulation of lipid membranes

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Sklenar, Heinz

    2014-01-01

    Biological membranes are complex assemblies of many different molecules of which analysis demands a variety of experimental and computational approaches. In this article, we explain challenges and advantages of atomistic Monte Carlo (MC) simulation of lipid membranes. We provide an introduction...... of local-move MC methods in combination with molecular dynamics simulations, for example, for studying multi-component lipid membranes containing cholesterol....

  12. Computational Modeling of Lipid Metabolism in Yeast

    Directory of Open Access Journals (Sweden)

    Vera Schützhold

    2016-09-01

    Full Text Available Lipid metabolism is essential for all major cell functions and has recently gained increasing attention in research and health studies. However, mathematical modeling by means of classical approaches such as stoichiometric networks and ordinary differential equation systems has not yet provided satisfactory insights, due to the complexity of lipid metabolism characterized by many different species with only slight differences and by promiscuous multifunctional enzymes.Here, we present a object-oriented stochastic model approach as a way to cope with the complex lipid metabolic network. While all lipid species are treated objects in the model, they can be modified by the respective converting reactions based on reaction rules, a hybrid method that integrates benefits of agent-based and classical stochastic simulation. This approach allows to follow the dynamics of all lipid species with different fatty acids, different degrees of saturation and different headgroups over time and to analyze the effect of parameter changes, potential mutations in the catalyzing enzymes or provision of different precursors. Applied to yeast metabolism during one cell cycle period, we could analyze the distribution of all lipids to the various membranes in time-dependent manner.The presented approach allows to efficiently treat the complexity of cellular lipid metabolism and to derive conclusions on the time- and location-dependent distributions of lipid species and their properties such as saturation. It is widely applicable, easily extendable and will provide further insights in healthy and diseased states of cell metabolism.

  13. A comprehensive classification system for lipids

    NARCIS (Netherlands)

    Fahy, E.; Subramaniam, S.; Brown, H.A.; Glass, C.K.; Merrill, A.H.; Murphy, R.C.; Raetz, C.R.H.; Russell, D.W.; Seyama, Y.; Shaw, W.; Shimizu, T.; Spener, F.; van Meer, G.|info:eu-repo/dai/nl/068570368; VanNieuwenhze, M.S.; White, S.H.|info:eu-repo/dai/nl/304843539; Witztum, J.; Dennis, E.A.

    2005-01-01

    Lipids are produced, transported, and recognized by the concerted actions of numerous enzymes, binding proteins, and receptors. A comprehensive analysis of lipid molecules, “lipidomics,” in the context of genomics and proteomics is crucial to understanding cellular physiology and pathology;

  14. GABA interaction with lipids in organic medium

    International Nuclear Information System (INIS)

    Beltramo, D.; Kivatinitz, S.; Lassaga, E.; Arce, A.

    1987-01-01

    The interaction of 3 H-GABA and 14 C-glutamate with lipids in an aqueous organic partition system was studied. With this partition system 3 H-GABA and 14 C-glutamate were able to interact with sphingomyelin, sulfatide, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidic acid but not with cholesterol or ceramide. In an homogeneous aqueous medium the authors could not demonstrate any interaction between 3 H-GABA-lipids. The apparent dissociation constants (K/sub d/) for 3 H-GABA-lipids or 14 C-glutamate-lipids interactions inorganic medium were in the millimolar range and maximal charge between 3 and 7 moles of GABA or glutamate by mole of lipid. Amino acids such as glutamic acid, β-alanine and glycine displaced 3 H-GABA with the same potency as GABA itself; thus these results show that the interaction lacks pharmacological specificity. To detect this interaction lipid concentrations higher than 2 μM were required and in the partition system 3 H-GABA and lipid phosphorus were both concentrated at the interface. Therefore, lipids tested with a biphasic partition system do not fulfill the classical criteria for a neurotransmitter receptor at least not for GABA and glutamate. 15 references, 1 figure, 3 tables

  15. Lipid transport and human brain development.

    Science.gov (United States)

    Betsholtz, Christer

    2015-07-01

    How the human brain rapidly builds up its lipid content during brain growth and maintains its lipids in adulthood has remained elusive. Two new studies show that inactivating mutations in MFSD2A, known to be expressed specifically at the blood-brain barrier, lead to microcephaly, thereby offering a simple and surprising solution to an old enigma.

  16. Lateral pressure profiles in lipid monolayers

    NARCIS (Netherlands)

    Baoukina, Svetlana; Marrink, Siewert J.; Tieleman, D. Peter

    2010-01-01

    We have used molecular dynamics simulations with coarse-grained and atomistic models to study the lateral pressure profiles in lipid monolayers. We first consider simple oil/air and oil/water interfaces, and then proceed to lipid monolayers at air/water and oil/water interfaces. The results are

  17. Amylose folding under the influence of lipids

    NARCIS (Netherlands)

    Lopez, Cesar A.; de Vries, Alex H.; Marrink, Siewert J.

    2012-01-01

    The molecular dynamics simulation technique was used to study the folding and complexation process of a short amylose fragment in the presence of lipids. In aqueous solution, the amylose chain remains as an extended left-handed helix. After the addition of lipids in the system, however, we observe

  18. Preservation of Microbial Lipids in Geothermal Sinters

    NARCIS (Netherlands)

    Kaur, G.; Mountain, B.W.; Hopmans, E.C.; Pancost, R.D.

    2011-01-01

    Lipid biomarkers are widely used to study the earliest life on Earth and have been invoked as potential astrobiological markers, but few studies have assessed their survival and persistence in geothermal settings. Here, we investigate lipid preservation in active and inactive geothermal silica

  19. A study of the enhanced sensitizing capacity of a contact allergen in lipid vesicle formulations

    DEFF Research Database (Denmark)

    Simonsson, Carl; Madsen, Jakob Torp; Graneli, Annette

    2011-01-01

    , an indicator of a compounds sensitizing capacity, increased when RBITC was applied in lipid vesicles as compared to an ethanol:water (Et:W) solution. Micro-scale vesicles showed a slightly higher cell proliferative response compared to nano-scale vesicles. TPM imaging revealed that the vesicle formulations...... improved the skin penetration of RBITC compared to the Et:W solution. A strong fluorescent region in the stratum corneum and upper epidermis implies elevated association of RBITC to these skin layers when formulated in lipid vesicles. In conclusion, the results indicate that there could be an elevated risk...... of sensitization when haptens are delivered in vehicles containing lipid vesicles. Although the size of the vesicles seems to be of minor importance, further studies are needed before a more generalized conclusion can be drawn. It is likely that the enhanced sensitizing capacity is a consequence of the improved...

  20. The lipid content of cisplatin- and doxorubicin-resistant MCF-7 human breast cancer cells.

    Science.gov (United States)

    Todor, I N; Lukyanova, N Yu; Chekhun, V F

    2012-07-01

    To perform the comparative study both of qualitative and quantitative content of lipids in parental and drug resistant breast cancer cells. Parental (MCF-7/S) and resistant to cisplatin (MCF-7/CP) and doxorubicin (MCF-7/Dox) human breast cancer cells were used in the study. Cholesterol, total lipids and phospholipids content were determined by means of thin-layer chromatography. It was found that cholesterol as well as cholesterol ethers content are significantly higher but diacylglycerols, triacyl-glycerols content are significantly lower in resistant cell strains than in parental (sensitive) cells. Moreover the analysis of individual phospholipids showed the increase of sphingomyelin, phosphatidylserine, cardiolipin, phosphatidic acid and the decrease of phosphatidy-lethanolamine, phosphatidylcholine in MCF-7/CP and MCF-7/Dox cells. Obtained results allow to suggest that the lipid profile changes can mediate the modulation of membrane fluidity in drug resistant MCF-7 breast cancer cells.

  1. Low density lipoprotein: structure, dynamics, and interactions of apoB-100 with lipids

    DEFF Research Database (Denmark)

    Murtola, T.; Vuorela, T. A.; Hyvonen, M. T.

    2011-01-01

    's structural information makes it more difficult to understand its function. In this work, we have combined experimental and theoretical data to construct LDL models comprised of the apoB-100 protein wrapped around a lipid droplet of about 20 nm in size. The models are considered by near-atomistic multi......-microsecond simulations to unravel structural as well as dynamical properties of LDL, with particular attention paid to lipids and their interactions with the protein. We find that the distribution and the ordering of the lipids in the LDL particle are rather complex. The previously proposed 2- and 3- layer models turn......Low-density lipoprotein (LDL) transports cholesterol in the bloodstream and plays an important role in the development of cardiovascular diseases, in particular atherosclerosis. Despite its importance to health, the structure of LDL is not known in detail. This is worrying since the lack of LDL...

  2. Developmental plasticity of cutaneous water loss and lipid composition in stratum corneum of desert and mesic nestling house sparrows.

    Science.gov (United States)

    Muñoz-Garcia, Agustí; Williams, Joseph B

    2008-10-07

    Intercellular lipids of the stratum corneum (SC), the outer layer of the epidermis, form a barrier to water vapor diffusion through the skin. Previously, we measured cutaneous water loss (CWL) and lipid composition of the SC of adult house sparrows from two populations, one living in the deserts of Saudi Arabia and another living in mesic Ohio. Adult desert house sparrows had a lower CWL, a lower proportion of free fatty acids, and a higher proportion of ceramides and cerebrosides in the SC compared with mesic sparrows. In this study, we investigated developmental plasticity of CWL and lipid composition of the SC in desert and mesic nestling house sparrows reared in low and high humidity and compared our results with previous work on adults. We measured CWL of nestlings and analyzed the lipid composition of the SC using thin-layer chromatography. We showed that nestling house sparrows from both localities had higher CWL than adults in their natural environment, a result of major modifications of the lipid composition of the SC. The expression of plasticity in CWL seems to be a response to opposed selection pressures, thermoregulation and water conservation, at different life stages, on which regulation of CWL plays a crucial role. Desert nestlings showed a greater degree of plasticity in CWL and lipid composition of the SC than did mesic nestlings, a finding consistent with the idea that organisms exposed to more environmental stress ought to be more plastic than individuals living in more benign environments.

  3. Multi-layer monochromator

    International Nuclear Information System (INIS)

    Schoenborn, B.P.; Caspar, D.L.D.

    1975-01-01

    This invention provides an artificial monochromator crystal for efficiently selecting a narrow band of neutron wavelengths from a neutron beam having a Maxwellian wavelength distribution, by providing on a substrate a plurality of germanium layers, and alternate periodic layers of a different metal having tailored thicknesses, shapes, and volumetric and neutron scattering densities. (U.S.)

  4. Ozone Layer Protection

    Science.gov (United States)

    ... and Research Centers Contact Us Share Ozone Layer Protection The stratospheric ozone layer is Earth’s “sunscreen” – protecting ... GreenChill Partnership Responsible Appliance Disposal (RAD) Program Ozone Protection vs. Ozone Pollution This website addresses stratospheric ozone ...

  5. Skin layer mechanics

    NARCIS (Netherlands)

    Geerligs, M.

    2010-01-01

    The human skin is composed of several layers, each with an unique structure and function. Knowledge about the mechanical behavior of these skin layers is important for clinical and cosmetic research, such as the development of personal care products and the understanding of skin diseases. Until

  6. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  7. Multifaceted role of lipids in Mycobacterium leprae.

    Science.gov (United States)

    Kaur, Gurkamaljit; Kaur, Jagdeep

    2017-03-01

    Mycobacterium leprae must adopt a metabolic strategy and undergo various metabolic alterations upon infection to survive inside the human body for years in a dormant state. A change in lipid homeostasis upon infection is highly pronounced in Mycobacterium leprae. Lipids play an essential role in the survival and pathogenesis of mycobacteria. Lipids are present in several forms and serve multiple roles from being a source of nutrition, providing rigidity, evading the host immune response to serving as virulence factors, etc. The synthesis and degradation of lipids is a highly regulated process and is the key to future drug designing and diagnosis for mycobacteria. In the current review, an account of the distinct roles served by lipids, the mechanism of their synthesis and degradation has been elucidated.

  8. Genetic architecture of circulating lipid levels

    DEFF Research Database (Denmark)

    Demirkan, Ayşe; Amin, Najaf; Isaacs, Aaron

    2011-01-01

    Serum concentrations of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TGs) and total cholesterol (TC) are important heritable risk factors for cardiovascular disease. Although genome-wide association studies (GWASs) of circulating lipid...... the ENGAGE Consortium GWAS on serum lipids, were applied to predict lipid levels in an independent population-based study, the Rotterdam Study-II (RS-II). We additionally tested for evidence of a shared genetic basis for different lipid phenotypes. Finally, the polygenic score approach was used to identify...... an alternative genome-wide significance threshold before pathway analysis and those results were compared with those based on the classical genome-wide significance threshold. Our study provides evidence suggesting that many loci influencing circulating lipid levels remain undiscovered. Cross-prediction models...

  9. Computer Simulations of Lipid Bilayers and Proteins

    DEFF Research Database (Denmark)

    Sonne, Jacob

    2006-01-01

    The importance of computer simulations in lipid bilayer research has become more prominent for the last couple of decades and as computers get even faster, simulations will play an increasingly important part of understanding the processes that take place in and across cell membranes. This thesis...... entitled Computer simulations of lipid bilayers and proteins describes two molecular dynamics (MD) simulation studies of pure lipid bilayers as well as a study of a transmembrane protein embedded in a lipid bilayer matrix. Below follows a brief overview of the thesis. Chapter 1. This chapter is a short...... in the succeeding chapters is presented. Details on system setups, simulation parameters and other technicalities can be found in the relevant chapters. Chapter 3, DPPC lipid parameters: The quality of MD simulations is intimately dependent on the empirical potential energy function and its parameters, i...

  10. Role of lipids in bacterial radioresistance

    International Nuclear Information System (INIS)

    Abushady, M.R.; Fawkia, M.E.; Tawfik, Z.S.

    1992-01-01

    The radioresistance of three bacterial isolates was determined. S. aureus was the most sensitive one (D 1 0 value 0.14 KGy), B. coagulans was moderate resistant (D 1 0 value 3.3 KGy) and the most resistant one was B.megaterium (D 1 0 value 3.7 KGy). Total lipids and lipid patterns of these bacteria were determined and the role of lipids in radioresistance was investigated. Least amount of total lipids was detected in the most sensitive organism (S. aureus). The increase in the bacterial content of total lipids was concomitant with high degrees of radioresistance. The most resistant organism (B. megaterium was characterized by high content of methyl esters of fatty acids, phosphatidylcholine and phosphatidylethanolamine, followed by appreciable amounts in the moderate resistant (B. coagulans) and the least amounts were detected in the most sensitive organism (S.aureus).6 fig., 3 tab

  11. [Germ cell membrane lipids in spermatogenesis].

    Science.gov (United States)

    Wang, Ting; Shi, Xiao; Quan, Song

    2016-05-01

    Spermatogenesis is a complex developmental process in which a diploid progenitor germ cell transforms into highly specialized spermatozoa. During spermatogenesis, membrane remodeling takes place, and cell membrane permeability and liquidity undergo phase-specific changes, which are all associated with the alteration of membrane lipids. Lipids are important components of the germ cell membrane, whose volume and ratio fluctuate in different phases of spermatogenesis. Abnormal lipid metabolism can cause spermatogenic dysfunction and consequently male infertility. Germ cell membrane lipids are mainly composed of cholesterol, phospholipids and glycolipids, which play critical roles in cell adhesion and signal transduction during spermatogenesis. An insight into the correlation of membrane lipids with spermatogenesis helps us to better understand the mechanisms of spermatogenesis and provide new approaches to the diagnosis and treatment of male infertility.

  12. Development of boundary layers

    International Nuclear Information System (INIS)

    Herbst, R.

    1980-01-01

    Boundary layers develop along the blade surfaces on both the pressure and the suction side in a non-stationary flow field. This is due to the fact that there is a strongly fluctuating flow on the downstream blade row, especially as a result of the wakes of the upstream blade row. The author investigates the formation of boundary layers under non-stationary flow conditions and tries to establish a model describing the non-stationary boundary layer. For this purpose, plate boundary layers are measured, at constant flow rates but different interferent frequency and variable pressure gradients. By introducing the sample technique, measurements of the non-stationary boundary layer become possible, and the flow rate fluctuation can be divided in its components, i.e. stochastic turbulence and periodical fluctuation. (GL) [de

  13. Improved electron transport layer

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides: a method of preparing a coating ink for forming a zinc oxide electron transport layer, comprising mixing zinc acetate and a wetting agent in water or methanol; a coating ink comprising zinc acetate and a wetting agent in aqueous solution or methanolic solution......; a method of preparing a zinc oxide electron transporting layer, which method comprises: i) coating a substrate with the coating ink of the present invention to form a film; ii) drying the film; and iii) heating the dry film to convert the zinc acetate substantially to ZnO; a method of preparing an organic...... photovoltaic device or an organic LED having a zinc oxide electron transport layer, the method comprising, in this order: a) providing a substrate bearing a first electrode layer; b) forming an electron transport layer according to the following method: i) coating a coating ink comprising an ink according...

  14. Lipid alterations in lipid rafts from Alzheimer's disease human brain cortex.

    Science.gov (United States)

    Martín, Virginia; Fabelo, Noemí; Santpere, Gabriel; Puig, Berta; Marín, Raquel; Ferrer, Isidre; Díaz, Mario

    2010-01-01

    Lipid rafts are membrane microdomains intimately associated with cell signaling. These biochemical microstructures are characterized by their high contents of sphingolipids, cholesterol and saturated fatty acids and a reduced content of polyunsaturated fatty acids (PUFA). Here, we have purified lipid rafts of human frontal brain cortex from normal and Alzheimer's disease (AD) and characterized their biochemical lipid composition. The results revealed that lipid rafts from AD brains exhibit aberrant lipid profiles compared to healthy brains. In particular, lipid rafts from AD brains displayed abnormally low levels of n-3 long chain polyunsaturated fatty acids (LCPUFA, mainly 22:6n-3, docosahexaenoic acid) and monoenes (mainly 18:1n-9, oleic acid), as well as reduced unsaturation and peroxidability indexes. Also, multiple relationships between phospholipids and fatty acids were altered in AD lipid rafts. Importantly, no changes were observed in the mole percentage of lipid classes and fatty acids in rafts from normal brains throughout the lifespan (24-85 years). These indications point to the existence of homeostatic mechanisms preserving lipid raft status in normal frontal cortex. The disruption of such mechanisms in AD brains leads to a considerable increase in lipid raft order and viscosity, which may explain the alterations in lipid raft signaling observed in AD.

  15. Using fluorescent lipids in live zebrafish larvae: From imaging whole animal physiology to subcellular lipid trafficking.

    Science.gov (United States)

    Anderson, J L; Carten, J D; Farber, S A

    2016-01-01

    Lipids serve essential functions in cells as signaling molecules, membrane components, and sources of energy. Defects in lipid metabolism are implicated in a number of pandemic human diseases, including diabetes, obesity, and hypercholesterolemia. Many aspects of how fatty acids and cholesterol are absorbed and processed by intestinal cells remain unclear and present a hurdle to developing approaches for disease prevention and treatment. Numerous studies have shown that the zebrafish is an excellent model for vertebrate lipid metabolism. In this chapter, we review commercially available fluorescent lipids that can be deployed in live zebrafish to better understand lipid signaling and metabolism. In this chapter, we present criteria one should consider when selecting specific fluorescent lipids for the study of digestive physiology or lipid metabolism in larval zebrafish. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. 2011 Plant Lipids: Structure, Metabolism, & Function Gordon Research Conference

    Energy Technology Data Exchange (ETDEWEB)

    Christopher Benning

    2011-02-04

    This is the second Gordon Research Conference on 'Plant Lipids: Structure, Metabolism & Function'. It covers current topics in lipid structure, metabolism and function in eukaryotic photosynthetic organisms including seed plants, algae, mosses and ferns. Work in photosynthetic bacteria is considered as well as it serves the understanding of specific aspects of lipid metabolism in plants. Breakthroughs are discussed in research on plant lipids as diverse as glycerolipids, sphingolipids, lipids of the cell surface, isoprenoids, fatty acids and their derivatives. The program covers nine concepts at the forefront of research under which afore mentioned plant lipid classes are discussed. The goal is to integrate areas such as lipid signaling, basic lipid metabolism, membrane function, lipid analysis, and lipid engineering to achieve a high level of stimulating interaction among diverse researchers with interests in plant lipids. One Emphasis is on the dynamics and regulation of lipid metabolism during plant cell development and in response to environmental factors.

  17. Lipid and carotenoid cooperation-driven adaptation to light and temperature stress in Synechocystis sp. PCC6803.

    Science.gov (United States)

    Zakar, Tomas; Herman, Eva; Vajravel, Sindhujaa; Kovacs, Laszlo; Knoppová, Jana; Komenda, Josef; Domonkos, Ildiko; Kis, Mihaly; Gombos, Zoltan; Laczko-Dobos, Hajnalka

    2017-05-01

    Polyunsaturated lipids are important components of photosynthetic membranes. Xanthophylls are the main photoprotective agents, can assist in protection against light stress, and are crucial in the recovery from photoinhibition. We generated the xanthophyll- and polyunsaturated lipid-deficient ROAD mutant of Synechocystis sp. PCC6803 (Synechocystis) in order to study the little-known cooperative effects of lipids and carotenoids (Cars). Electron microscopic investigations confirmed that in the absence of xanthophylls the S-layer of the cellular envelope is missing. In wild-type (WT) cells, as well as the xanthophyll-less (RO), polyunsaturated lipid-less (AD), and the newly constructed ROAD mutants the lipid and Car compositions were determined by MS and HPLC, respectively. We found that, relative to the WT, the lipid composition of the mutants was remodeled and the Car content changed accordingly. In the mutants the ratio of non-bilayer-forming (NBL) to bilayer-forming (BL) lipids was found considerably lower. Xanthophyll to β-carotene ratio increased in the AD mutant. In vitro and in vivo methods demonstrated that saturated, monounsaturated lipids and xanthophylls may stabilize the trimerization of Photosystem I (PSI). Fluorescence induction and oxygen-evolving activity measurements revealed increased light sensitivity of RO cells compared to those of the WT. ROAD showed a robust increase in light susceptibility and reduced recovery capability, especially at moderate low (ML) and moderate high (MH) temperatures, indicating a cooperative effect of xanthophylls and polyunsaturated lipids. We suggest that both lipid unsaturation and xanthophylls are required for providing the proper structure and functioning of the membrane environment that protects against light and temperature stress. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Boosting water oxidation layer-by-layer.

    Science.gov (United States)

    Hidalgo-Acosta, Jonnathan C; Scanlon, Micheál D; Méndez, Manuel A; Amstutz, Véronique; Vrubel, Heron; Opallo, Marcin; Girault, Hubert H

    2016-04-07

    Electrocatalysis of water oxidation was achieved using fluorinated tin oxide (FTO) electrodes modified with layer-by-layer deposited films consisting of bilayers of negatively charged citrate-stabilized IrO2 NPs and positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer. The IrO2 NP surface coverage can be fine-tuned by controlling the number of bilayers. The IrO2 NP films were amorphous, with the NPs therein being well-dispersed and retaining their as-synthesized shape and sizes. UV/vis spectroscopic and spectro-electrochemical studies confirmed that the total surface coverage and electrochemically addressable surface coverage of IrO2 NPs increased linearly with the number of bilayers up to 10 bilayers. The voltammetry of the modified electrode was that of hydrous iridium oxide films (HIROFs) with an observed super-Nernstian pH response of the Ir(III)/Ir(IV) and Ir(IV)-Ir(IV)/Ir(IV)-Ir(V) redox transitions and Nernstian shift of the oxygen evolution onset potential. The overpotential of the oxygen evolution reaction (OER) was essentially pH independent, varying only from 0.22 V to 0.28 V (at a current density of 0.1 mA cm(-2)), moving from acidic to alkaline conditions. Bulk electrolysis experiments revealed that the IrO2/PDDA films were stable and adherent under acidic and neutral conditions but degraded in alkaline solutions. Oxygen was evolved with Faradaic efficiencies approaching 100% under acidic (pH 1) and neutral (pH 7) conditions, and 88% in alkaline solutions (pH 13). This layer-by-layer approach forms the basis of future large-scale OER electrode development using ink-jet printing technology.

  19. Transfer of seston lipids during a flagellate bloom from the surface to the benthic community in the Weddell Sea

    Directory of Open Access Journals (Sweden)

    Sergio Rossi

    2013-09-01

    Full Text Available Total lipid and fatty acid concentrations were studied in a late spring-early summer flagellate-dominated bloom in the Weddell Sea. These indicators were considered a good tool for assessing the quality of organic matter settling from surface to deep-water layers (epibenthic water layers. The results showed different patterns between the early (11-15 December 2003 and the late sampling period (18-27 December 2003 at all studied depths (5 m, 50 m and near-bottom water layers. Low phytoplankton biomass (mainly flagellates in the first half of the study corresponded to low total lipid and fatty acid concentrations. In the second sampling period a spring bloom (mainly flagellates and diatoms was detected, increasing the total lipid and fatty acid concentrations in the water column. The amount of settling organic matter from surface waters to the near-bottom water layers was high, especially in the late sampling period. Trophic markers showed evidence of a sink of available organic matter rich in quality and quantity, especially in terms of polyunsaturated fatty acids, for benthic organisms from surface layers to bottom layers in only a few days. The importance of studying short-time cycles in order to detect organic matter availability for benthic biota in view of the pulse-like dynamics of primary production in Antarctic waters is discussed.

  20. A lipid E-MAP identifies Ubx2 as a critical regulator of lipid saturation and lipid bilayer stress

    DEFF Research Database (Denmark)

    Surma, Michal A; Klose, Christian; Peng, Debby

    2013-01-01

    Biological membranes are complex, and the mechanisms underlying their homeostasis are incompletely understood. Here, we present a quantitative genetic interaction map (E-MAP) focused on various aspects of lipid biology, including lipid metabolism, sorting, and trafficking. This E-MAP contains ∼250......,000 negative and positive genetic interaction scores and identifies a molecular crosstalk of protein quality control pathways with lipid bilayer homeostasis. Ubx2p, a component of the endoplasmic-reticulum-associated degradation pathway, surfaces as a key upstream regulator of the essential fatty acid (FA...

  1. Triglyceride Blisters in Lipid Bilayers: Implications for Lipid Droplet Biogenesis and the Mobile Lipid Signal in Cancer Cell Membranes

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Duelund, Lars; Pakkanen, Kirsi Inkeri

    2010-01-01

    triolein molecules to the bilayer center in the form of a disordered, isotropic, mobile neutral lipid aggregate, at least 17 nm in diameter, which forms spontaneously, and remains stable on at least the microsecond time scale. The results give credence to the hotly debated existence of mobile neutral lipid...... aggregates of unknown function present in malignant cells, and to the early biogenesis of lipid droplets accommodated between the two leaflets of the endoplasmic reticulum membrane. The TO aggregates give the bilayer a blister-like appearance, and will hinder the formation of multi-lamellar phases in model...

  2. Applications and limitations of lipid nanoparticles in dermal and transdermal drug delivery via the follicular route.

    Science.gov (United States)

    Lauterbach, Andreas; Müller-Goymann, Christel C

    2015-11-01

    Lipid nanoparticles (LN) such as solid lipid nanoparticles (SLN) and nanolipid carriers (NLC) feature several claimed benefits for topical drug therapy including biocompatible ingredients, drug release modification, adhesion to the skin, and film formation with subsequent hydration of the superficial skin layers. However, penetration and permeation into and across deeper skin layers are restricted due to the barrier function of the stratum corneum (SC). As different kinds of nanoparticles provide the potential for penetration into hair follicles (HF) LN are applicable drug delivery systems (DDS) for this route in order to enhance the dermal and transdermal bioavailability of active pharmaceutical ingredients (API). Therefore, this review addresses the HF as application site, published formulations of LN which showed follicular penetration (FP), and characterization methods in order to identify and quantify the accumulation of API delivered by the LN in the HF. Since LN are based on lipids that appear in human sebum which is the predominant medium in HF an increased localization of the colloidal carriers as well as a promoted drug release may be assumed. Therefore, sebum-like lipid material and a size of less or equal 640 nm are appropriate specifications for FP of particulate formulations. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Gastric emptying and intragastric distribution of lipids in man. A new scintigraphic method of study

    International Nuclear Information System (INIS)

    Jian, R.; Vigneron, N.; Najean, Y.; Bernier, J.J.

    1982-01-01

    We measured gastric emptying of fat and water from a solid-liquid meal in healthy volunteers using a tubeless scintigraphic method. 75 Se glycerol triether, incorporated in butter, was the lipid-phase marker, and /sup 99m/Tcm, ingested with 250 ml water, the non-lipid phase marker. In seven of these subjects we also measured the gastric emptying of solids and liquids with /sup 99m/Tc bound to cooked egg whites as the solid-phase marker and 111 In ingested with 250 ml water as the marker of the solid and aqueous phases. Emptying and intragastric repartition of each marker were measured by detection of radioactivity changes over the abdominal area using a gamma-camera. The stability and the specificity of the labeling was checked for each marker. Mean gastric emptying rate (expressed as percentage ingested marker emptied per hr) of lipids (17.4 +/- 2.4) was much lower than that of the rest of the meal (34.2 +/- 1.8) and slightly, but significantly, lower than that of solids (22.8 +/- 1.8). An intragastric layering of fat above nonlipids was observed only after the first postprandial hour and remained moderate. Thus, lipids are emptied more slowly than any other component of an ordinary meal, and this is not due only to layering of fat above water

  4. Gastric emptying and intragastric distribution of lipids in man. A new scintigraphic method of study

    Energy Technology Data Exchange (ETDEWEB)

    Jian, R.; Vigneron, N.; Najean, Y.; Bernier, J.J.

    1982-08-01

    We measured gastric emptying of fat and water from a solid-liquid meal in healthy volunteers using a tubeless scintigraphic method. /sup 75/Se glycerol triether, incorporated in butter, was the lipid-phase marker, and /sup 99m/Tcm, ingested with 250 ml water, the non-lipid phase marker. In seven of these subjects we also measured the gastric emptying of solids and liquids with /sup 99m/Tc bound to cooked egg whites as the solid-phase marker and /sup 111/In ingested with 250 ml water as the marker of the solid and aqueous phases. Emptying and intragastric repartition of each marker were measured by detection of radioactivity changes over the abdominal area using a gamma-camera. The stability and the specificity of the labeling was checked for each marker. Mean gastric emptying rate (expressed as percentage ingested marker emptied per hr) of lipids (17.4 +/- 2.4) was much lower than that of the rest of the meal (34.2 +/- 1.8) and slightly, but significantly, lower than that of solids (22.8 +/- 1.8). An intragastric layering of fat above nonlipids was observed only after the first postprandial hour and remained moderate. Thus, lipids are emptied more slowly than any other component of an ordinary meal, and this is not due only to layering of fat above water.

  5. The Application of Layer Theory to Design: The Control Layer

    Science.gov (United States)

    Gibbons, Andrew S.; Langton, Matthew B.

    2016-01-01

    A theory of design layers proposed by Gibbons ("An Architectural Approach to Instructional Design." Routledge, New York, 2014) asserts that each layer of an instructional design is related to a body of theory closely associated with the concerns of that particular layer. This study focuses on one layer, the control layer, examining…

  6. Lipid content and fatty acid composition of green algae Scenedesmus obliquus grown in a constant cell density apparatus

    Science.gov (United States)

    Choi, K. J.; Nakhost, Z.; Barzana, E.; Karel, M.

    1987-01-01

    The lipids of alga Scenedesmus obliquus grown under controlled conditions were separated and fractionated by column and thin-layer chromatography, and fatty acid composition of each lipid component was studied by gas-liquid chromatography (GLC). Total lipids were 11.17%, and neutral lipid, glycolipid and phospholipid fractions were 7.24%, 2.45% and 1.48% on a dry weight basis, respectively. The major neutral lipids were diglycerides, triglycerides, free sterols, hydrocarbons and sterol esters. The glycolipids were: monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. The phospholipids included: phosphatidyl choline, phosphatidyl glycerol and phosphatidyl ethanolamine. Fourteen fatty acids were identified in the four lipid fractions by GLC. The main fatty acids were C18:2, C16:0, C18:3(alpha), C18:1, C16:3, C16:1, and C16:4. Total unsaturated fatty acid and essential fatty acid compositions of the total algal lipids were 80% and 38%, respectively.

  7. Topologically nontrivial quantum layers

    International Nuclear Information System (INIS)

    Carron, G.; Exner, P.; Krejcirik, D.

    2004-01-01

    Given a complete noncompact surface Σ embedded in R 3 , we consider the Dirichlet Laplacian in the layer Ω that is defined as a tubular neighborhood of constant width about Σ. Using an intrinsic approach to the geometry of Ω, we generalize the spectral results of the original paper by Duclos et al. [Commun. Math. Phys. 223, 13 (2001)] to the situation when Σ does not possess poles. This enables us to consider topologically more complicated layers and state new spectral results. In particular, we are interested in layers built over surfaces with handles or several cylindrically symmetric ends. We also discuss more general regions obtained by compact deformations of certain Ω

  8. The multifaceted interplay between lipids and epigenetics.

    Science.gov (United States)

    Dekkers, Koen F; Slagboom, P Eline; Jukema, J Wouter; Heijmans, Bastiaan T

    2016-06-01

    The interplay between lipids and epigenetic mechanisms has recently gained increased interest because of its relevance for common diseases and most notably atherosclerosis. This review discusses recent advances in unravelling this interplay with a particular focus on promising approaches and methods that will be able to establish causal relationships. Complementary approaches uncovered close links between circulating lipids and epigenetic mechanisms at multiple levels. A characterization of lipid-associated genetic variants suggests that these variants exert their influence on lipid levels through epigenetic changes in the liver. Moreover, exposure of monocytes to lipids persistently alters their epigenetic makeup resulting in more proinflammatory cells. Hence, epigenetic changes can both impact on and be induced by lipids. It is the combined application of technological advances to probe epigenetic modifications at a genome-wide scale and methodological advances aimed at causal inference (including Mendelian randomization and integrative genomics) that will elucidate the interplay between circulating lipids and epigenetics. Understanding its role in the development of atherosclerosis holds the promise of identifying a new category of therapeutic targets, since epigenetic changes are amenable to reversal.

  9. Wafer-scale fabrication of glass-FEP-glass microfluidic devices for lipid bilayer experiments.

    Science.gov (United States)

    Bomer, Johan G; Prokofyev, Alexander V; van den Berg, Albert; Le Gac, Séverine

    2014-12-07

    We report a wafer-scale fabrication process for the production of glass-FEP-glass microdevices using UV-curable adhesive (NOA81) as gluing material, which is applied using a novel "spin & roll" approach. Devices are characterized for the uniformity of the gluing layer, presence of glue in the microchannels, and alignment precision. Experiments on lipid bilayers with electrophysiological recordings using a model pore-forming polypeptide are demonstrated.

  10. Temperature dependent heterogeneous rotational correlation in lipids.

    Science.gov (United States)

    Dadashvand, Neda; Othon, Christina M

    2016-11-15

    Lipid structures exhibit complex and highly dynamic lateral structure; and changes in lipid density and fluidity are believed to play an essential role in membrane targeting and function. The dynamic structure of liquids on the molecular scale can exhibit complex transient density fluctuations. Here the lateral heterogeneity of lipid dynamics is explored in free standing lipid monolayers. As the temperature is lowered the probes exhibit increasingly broad and heterogeneous rotational correlation. This increase in heterogeneity appears to exhibit a critical onset, similar to those observed for glass forming fluids. We explore heterogeneous relaxation in in a single constituent lipid monolayer of 1, 2-dimyristoyl-sn-glycero-3-phosphocholine  by measuring the rotational diffusion of a fluorescent probe (1-palmitoyl-2-[1]-sn-glycero-3-phosphocholine), which is embedded in the lipid monolayer at low labeling density. Dynamic distributions are measured using wide-field time-resolved fluorescence anisotropy. The observed relaxation exhibits a narrow, liquid-like distribution at high temperatures (τ ∼ 2.4 ns), consistent with previous experimental measures (Dadashvand et al 2014 Struct. Dyn. 1 054701, Loura and Ramalho 2007 Biochim. Biophys. Acta 1768 467-478). However, as the temperature is quenched, the distribution broadens, and we observe the appearance of a long relaxation population (τ ∼ 16.5 ns). This supports the heterogeneity observed for lipids at high packing densities, and demonstrates that the nanoscale diffusion and reorganization in lipid structures can be significantly complex, even in the simplest amorphous architectures. Dynamical heterogeneity of this form can have a significant impact on the organization, permeability and energetics of lipid membrane structures.

  11. Scenedesmus sp. NJ-1 isolated from Antarctica: a suitable renewable lipid source for biodiesel production.

    Science.gov (United States)

    Chen, Zhuo; Gong, Yangmin; Fang, Xiantao; Hu, Hanhua

    2012-11-01

    Microalgal lipids are promising alternative feedstocks for biodiesel production. Scenedesmus sp. NJ-1, an oil-rich freshwater microalga isolated from Antarctica, was identified to be a suitable candidate to produce biodiesel in this study. This strain could grow at temperatures ranging from 4 to 35 °C. With regular decrease in nitrate concentration in the medium, large quantities of triacylglycerols accumulated under batch culture conditions detected by thin layer chromatography and BODIPY 505/515 fluorescent staining. Scenedesmus sp. NJ-1 achieved the average biomass productivity of 0.105 g l⁻¹ d⁻¹ (dry weight) and nearly the highest lipid content (35 % of dry cell weight) was reached at day 28 in the batch culture. Neutral lipids accounted for 78 % of total lipids, and C18:1 (n-9), C16:0 were the major fatty acids in total lipids, composing 37 and 20 % of total fatty acids of Scenedesmus sp. NJ-1 grown for 36 days, respectively. These results suggested that Scenedesmus sp. NJ-1 was a good source of microalgal oils for biodiesel production.

  12. Effect of piroxicam on lipid membranes: Drug encapsulation and gastric toxicity aspects.

    Science.gov (United States)

    Wilkosz, Natalia; Rissanen, Sami; Cyza, Małgorzata; Szybka, Renata; Nowakowska, Maria; Bunker, Alex; Róg, Tomasz; Kepczynski, Mariusz

    2017-03-30

    Uptake of piroxicam, a non-steroidal anti-inflammatory drug, from the intestines after oral intake is limited due to its low solubility and its wide use is associated with several side effects related to the gastrointestinal tract. In this study, all-atom molecular dynamics (MD) simulations and fluorescent spectroscopy were employed to investigate the interaction of piroxicam in neutral, zwitterionic, and cationic forms with lipid bilayers composed of phosphatidylcholine, cholesterol, and PEGylated lipids. Our study was aimed to assess the potential for encapsulation of piroxicam in liposomal carriers and to shed more light on the process of gastrointestinal tract injury by the drug. Through both the MD simulations and laser scanning confocal microscopy, we have demonstrated that all forms of piroxicam can associate with the lipid bilayers and locate close to the water-membrane interface. Conventional liposomes used in drug delivery are usually stabilized by the addition of cholesterol and have their bloodstream lifetime extended through the inclusion of PEGylated lipids in the formulation to create a protective polymer corona. For this reason, we tested the effect of these two modifications on the behavior of piroxicam in the membrane. When the bilayer was PEGylated, piroxicam localize to the PEG layer and within the lipid headgroup region. This suggests that PEGylated liposomes are capable of carrying a larger quantity of piroxicam than the conventional ones. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Age-Specific Lipid and Fatty Acid Profiles of Atlantic Salmon Juveniles in the Varzuga River

    Directory of Open Access Journals (Sweden)

    Svetlana A. Murzina

    2016-06-01

    Full Text Available The age-specific lipid and fatty acid profiles of juvenile Atlantic salmon at different ages (0+, 1+, and 2+ years after hatching from nests located in the mainstream of a large Arctic River, the Varzuga River, and resettling to the favorable Sobachji shoal in autumn before overwinter are herein presented. The contemporary methods of the lipid analysis were used: thin layer chromatography and gas chromatography. The results show that the stability of the regulation of important functions in developing organisms is maintained through structural alterations in lipids. These alterations can be considered as a sequence of the modifications and changes in the ratios of certain lipid classes and fatty acids constituents. In general, changes in the lipids and fatty acids (FAs maintained the physiological limits and controls through the adaptive systems of the organism. The mechanisms of juvenile fish biochemical adaptation to the environmental conditions in the studied biotope include the modification of the energy metabolism and anabolism, and here belongs to the energy characteristics of metabolic processes.

  14. Optimization of nanostructured lipid carriers for topical delivery of nimesulide using Box-Behnken design approach.

    Science.gov (United States)

    Moghddam, Seyedeh Marziyeh Mahdavi; Ahad, Abdul; Aqil, Mohd; Imam, Syed Sarim; Sultana, Yasmin

    2017-05-01

    The aim of the present study was to develop and optimize topically applied nimesulide-loaded nanostructured lipid carriers. Box-Behnken experimental design was applied for optimization of nanostructured lipid carriers. The independent variables were ratio of stearic acid: oleic acid (X 1 ), poloxamer 188 concentration (X 2 ) and lecithin concentration (X 3 ) while particle size (Y 1 ) and entrapment efficiency (Y 2 ) were the chosen responses. Further, skin penetration study, in vitro release, confocal laser scanning microscopy and stability study were also performed. The optimized nanostructured lipid carriers of nimesulide provide reasonable particle size, flux, and entrapment efficiency. Optimized formulation (F9) with mean particle size of 214.4 ± 11 nm showed 89.4 ± 3.40% entrapment efficiency and achieved mean flux 2.66 ± 0.09 μg/cm 2 /h. In vitro release study showed prolonged drug release from the optimized formulation following Higuchi release kinetics with R 2 value of 0.984. Confocal laser scanning microscopy revealed an enhanced penetration of Rhodamine B-loaded nanostructured lipid carriers to the deeper layers of the skin. The stability study confirmed that the optimized formulation was considerably stable at refrigerator temperature as compared to room temperature. Our results concluded that nanostructured lipid carriers are an efficient carrier for topical delivery of nimesulide.

  15. DNA release from lipoplexes by anionic lipids: correlation with lipid mesomorphism, interfacial curvature, and membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Tarahovsky, Yury S.; Koynova, Rumiana; MacDonald, Robert C. (Northwestern)

    2010-01-18

    DNA release from lipoplexes is an essential step during lipofection and is probably a result of charge neutralization by cellular anionic lipids. As a model system to test this possibility, fluorescence resonance energy transfer between DNA and lipid covalently labeled with Cy3 and BODIPY, respectively, was used to monitor the release of DNA from lipid surfaces induced by anionic liposomes. The separation of DNA from lipid measured this way was considerably slower and less complete than that estimated with noncovalently labeled DNA, and depends on the lipid composition of both lipoplexes and anionic liposomes. This result was confirmed by centrifugal separation of released DNA and lipid. X-ray diffraction revealed a clear correlation of the DNA release capacity of the anionic lipids with the interfacial curvature of the mesomorphic structures developed when the anionic and cationic liposomes were mixed. DNA release also correlated with the rate of fusion of anionic liposomes with lipoplexes. It is concluded that the tendency to fuse and the phase preference of the mixed lipid membranes are key factors for the rate and extent of DNA release. The approach presented emphasizes the importance of the lipid composition of both lipoplexes and target membranes and suggests optimal transfection may be obtained by tailoring lipoplex composition to the lipid composition of target cells.

  16. Lipid and Phylogenetic Analysis of a Gypsum-hosted Endoevaporitic Microbial Community

    Science.gov (United States)

    Turk, K. A.; Jahnke, L. L.; Green, S. J.; Kubo, M. D.; Vogel, M. B.; Des Marais, D. J.

    2007-12-01

    Gypsum evaporites host diverse, productive and volumetrically significant microbial communities and are relevant modern-day analogs to both Precambrian sabkha deposits and, potentially, Martian evaporites. Extensive evaporites form in subaqueous environments of high salinity ponds (>150 permil) maintained by the Exportadora de Sal, S. A. (ESSA) in Guerrero Negro, B.C.S., Mexico. A gypsarenite (reworked clastic gypsum) crust found along the southeast margin of ESSA's Pond 9 was collected in February 2004 and each vibrantly colored layer in the top centimeter was sampled. Extant microbial communities from each layer were characterized using complementary culture-independent molecular techniques, lipid biomarker analysis, and compound specific isotopic analysis. Coupling molecular analysis with lipid biomarker analysis revealed that oxygenic photosynthetic organisms dominate the surface layers (top 3 mm). Polar lipids from the surface layers consisted predominantly of glycolipids, which are characteristic of algae, cyanobacteria and green anoxygenic photosynthetic bacteria. Consistent with prior analyses of gypsum evaporites, 16S rRNA gene clone libraries indicate that cyanobacterial populations belong primarily to the genus Cyanothece. The bacterial community below the surface layers is more diverse and dominated by anaerobic organisms. Phototrophic purple sulfur bacteria, sulfate-reducing bacteria (SRB), and Bacteroidetes were particularly abundant. The relative abundances of SRB increased with depth; Desulfobacteraceae clones were distributed throughout the crust, but not at the surface, while Desulfovibrionaceae clones were found predominantly in the deepest layers. These molecular results are consistent with fatty acid biomarker analysis. δ13C values of major lipid classes in the crust and sediment range from 14 to 36‰, which is considerably lower than corresponding values for benthic Microcoleus-dominated cyanobacterial mats found at lower salinities at ESSA

  17. Effect of chemical permeation enhancers on stratum corneum barrier lipid organizational structure and interferon alpha permeability.

    Science.gov (United States)

    Moghadam, Shadi H; Saliaj, Evi; Wettig, Shawn D; Dong, Chilbert; Ivanova, Marina V; Huzil, J Torin; Foldvari, Marianna

    2013-06-03

    The outermost layer of the skin, known as the stratum corneum (SC), is composed of dead corneocytes embedded in an intercellular lipid matrix consisting of ceramides, free fatty acids, and cholesterol. The high level of organization within this matrix protects the body by limiting the permeation of most compounds through the skin. While essential for its protective functions, the SC poses a significant barrier for the delivery of topically applied pharmaceutical agents. Chemical permeation enhancers (CPEs) can increase delivery of small drug compounds into the skin by interacting with the intercellular lipids through physical processes including extraction, fluidization, increased disorder, and phase separation. However, it is not clear whether these same mechanisms are involved in delivery of biotherapeutic macromolecules, such as proteins. Here we describe the effect of three categories of CPEs {solvents [ethanol, propylene glycol, diethylene glycol monoethyl ether (transcutol), oleic acid], terpenes [menthol, nerol, camphor, methyl salicylate], and surfactants [Tween 80, SDS, benzalkonium chloride, polyoxyl 40 hydrogenated castor oil (Cremophor RH40), didecyldimethylammonium bromide (DDAB), didecyltrimethylammonium bromide (DTAB)]} on the lipid organizational structure of human SC as determined by X-ray scattering studies. Small- and wide-angle X-ray scattering studies were conducted to correlate the degree of structural changes and hydrocarbon chain packing in SC lipids caused by these various classes of CPEs to the extent of permeation of interferon alpha-2b (IFNα), a 19 kDa protein drug, into human skin. With the exception of solvents, propylene glycol and ethanol, all classes of CPEs caused increased disordering of lamellar and lateral packing of lipids. We observed that the highest degree of SC lipid disordering was caused by surfactants (especially SDS, DDAB, and DTAB) followed by terpenes, such as nerol. Interestingly, in vitro skin permeation studies

  18. Construction and Characterization of an Escherichia coli Mutant Producing Kdo2-Lipid A

    Directory of Open Access Journals (Sweden)

    Jianli Wang

    2014-03-01

    Full Text Available 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo2-lipid A is the conserved structure domain of lipopolysaccharide found in most Gram-negative bacteria, and it is believed to stimulate the innate immune system through the TLR4/MD2 complex. Therefore, Kdo2-lipid A is an important stimulator for studying the mechanism of the innate immune system and for developing bacterial vaccine adjuvants. Kdo2-lipid A has not been chemically synthesized to date and could only be isolated from an Escherichia coli mutant strain, WBB06. WBB06 cells grow slowly and have to grow in the presence of tetracycline. In this study, a novel E. coli mutant strain, WJW00, that could synthesize Kdo2-lipid A was constructed by deleting the rfaD gene from the genome of E. coli W3110. The rfaD gene encodes ADP-l-glycero-d-manno-heptose-6-epimerase RfaD. Based on the analysis by SDS-PAGE, thin layer chromatography (TLC and electrospray ionization mass spectrometry (ESI/MS, WJW00 could produce similar levels of Kdo2-lipid A to WBB06. WJW00 cells grow much better than WBB06 cells and do not need to add any antibiotics during growth. Compared with the wild-type strain, W3110, WJW00 showed increased hydrophobicity, higher cell permeability, greater autoaggregation and decreased biofilm-forming ability. Therefore, WJW00 could be a more suitable strain than WBB06 for producing Kdo2-lipid A and a good base strain for developing lipid A adjuvants.

  19. An ER Protein Functionally Couples Neutral Lipid Metabolism on Lipid Droplets to Membrane Lipid Synthesis in the ER

    DEFF Research Database (Denmark)

    Markgraf, Daniel F; Klemm, Robin W; Junker, Mirco

    2014-01-01

    Eukaryotic cells store neutral lipids such as triacylglycerol (TAG) in lipid droplets (LDs). Here, we have addressed how LDs are functionally linked to the endoplasmic reticulum (ER). We show that, in S. cerevisiae, LD growth is sustained by LD-localized enzymes. When LDs grow in early stationary...... phase, the diacylglycerol acyl-transferase Dga1p moves from the ER to LDs and is responsible for all TAG synthesis from diacylglycerol (DAG). During LD breakdown in early exponential phase, an ER membrane protein (Ice2p) facilitates TAG utilization for membrane-lipid synthesis. Ice2p has a cytosolic...... and explain how cells switch neutral lipid metabolism from storage to consumption....

  20. Lipid Configurations from Molecular Dynamics Simulations

    DEFF Research Database (Denmark)

    Pezeshkian, Weria; Khandelia, Himanshu; Marsh, Derek

    2018-01-01

    of dihedral angles in palmitoyl-oleoyl phosphatidylcholine from molecular dynamics simulations of hydrated fluid bilayer membranes. We compare results from the widely used lipid force field of Berger et al. with those from the most recent C36 release of the CHARMM force field for lipids. Only the CHARMM force......The extent to which current force fields faithfully reproduce conformational properties of lipids in bilayer membranes, and whether these reflect the structural principles established for phospholipids in bilayer crystals, are central to biomembrane simulations. We determine the distribution...

  1. Polymer-lipid hybrid nanoparticles as enhanced indomethacin delivery systems.

    Science.gov (United States)

    Dalmoro, Annalisa; Bochicchio, Sabrina; Nasibullin, Shamil F; Bertoncin, Paolo; Lamberti, Gaetano; Barba, Anna Angela; Moustafine, Rouslan I

    2018-05-17

    Non-steroidal anti-inflammatory drugs (NSAIDs), i.e. indomethacin used for rheumatoid arthritis and non-rheumatoid inflammatory diseases, are known for their injurious actions on the gastrointestinal (GI) tract. Mucosal damage can be avoided by using nanoscale systems composed by a combination of liposomes and biodegradable natural polymer, i.e. chitosan, for enhancing drug activity. Aim of this study was to prepare chitosan-lipid hybrid delivery systems for indomethacin dosage through a novel continuous method based on microfluidic principles. The drop-wise conventional method was also applied in order to investigate the effect of the two polymeric coverage processes on the nanostructures features and their interactions with indomethacin. Thermal-physical properties, mucoadhesiveness, drug entrapment efficiency, in vitro release behavior in simulated GI fluids and stability in stocking conditions were assayed and compared, respectively, for the uncoated and chitosan-coated nanoliposomes prepared by the two introduced methods. The prepared chitosan-lipid hybrid structures, with nanometric size, have shown high indomethacin loading (about 10%) and drug encapsulation efficiency up to 99%. TEM investigation has highlighted that the developed novel simil-microfluidic method is able to put a polymeric layer, surrounding indomethacin loaded nanoliposomes, thicker and smoother than that achievable by the drop-wise method, improving their storage stability. Finally, double pH tests have confirmed that the chitosan-lipid hybrid nanostructures have a gastro retentive behavior in simulated gastric and intestinal fluids thus can be used as delivery systems for the oral-controlled release of indomethacin. Based on the present results, the simil-microfluidic method, working with large volumes, in a rapid manner, without the use of drastic conditions and with a precise control over the covering process, seems to be the most promising method for the production of suitable

  2. Arctic Mixed Layer Dynamics

    National Research Council Canada - National Science Library

    Morison, James

    2003-01-01

    .... Over the years we have sought to understand the heat and mass balance of the mixed layer, marginal ice zone processes, the Arctic internal wave and mixing environment, summer and winter leads, and convection...

  3. Layered inorganic solids

    Czech Academy of Sciences Publication Activity Database

    Čejka, Jiří; Morris, R. E.; Nachtigall, P.; Roth, Wieslaw Jerzy

    2014-01-01

    Roč. 43, č. 27 (2014), s. 10274-10275 ISSN 1477-9226 Institutional support: RVO:61388955 Keywords : layered inorganic solids * physical chemistry * catalysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.197, year: 2014

  4. Addressing Ozone Layer Depletion

    Science.gov (United States)

    Access information on EPA's efforts to address ozone layer depletion through regulations, collaborations with stakeholders, international treaties, partnerships with the private sector, and enforcement actions under Title VI of the Clean Air Act.

  5. Layered Fault Management Architecture

    National Research Council Canada - National Science Library

    Sztipanovits, Janos

    2004-01-01

    ... UAVs or Organic Air Vehicles. The approach of this effort was to analyze fault management requirements of formation flight for fleets of UAVs, and develop a layered fault management architecture which demonstrates significant...

  6. The Bottom Boundary Layer.

    Science.gov (United States)

    Trowbridge, John H; Lentz, Steven J

    2018-01-03

    The oceanic bottom boundary layer extracts energy and momentum from the overlying flow, mediates the fate of near-bottom substances, and generates bedforms that retard the flow and affect benthic processes. The bottom boundary layer is forced by winds, waves, tides, and buoyancy and is influenced by surface waves, internal waves, and stratification by heat, salt, and suspended sediments. This review focuses on the coastal ocean. The main points are that (a) classical turbulence concepts and modern turbulence parameterizations provide accurate representations of the structure and turbulent fluxes under conditions in which the underlying assumptions hold, (b) modern sensors and analyses enable high-quality direct or near-direct measurements of the turbulent fluxes and dissipation rates, and (c) the remaining challenges include the interaction of waves and currents with the erodible seabed, the impact of layer-scale two- and three-dimensional instabilities, and the role of the bottom boundary layer in shelf-slope exchange.

  7. The Bottom Boundary Layer

    Science.gov (United States)

    Trowbridge, John H.; Lentz, Steven J.

    2018-01-01

    The oceanic bottom boundary layer extracts energy and momentum from the overlying flow, mediates the fate of near-bottom substances, and generates bedforms that retard the flow and affect benthic processes. The bottom boundary layer is forced by winds, waves, tides, and buoyancy and is influenced by surface waves, internal waves, and stratification by heat, salt, and suspended sediments. This review focuses on the coastal ocean. The main points are that (a) classical turbulence concepts and modern turbulence parameterizations provide accurate representations of the structure and turbulent fluxes under conditions in which the underlying assumptions hold, (b) modern sensors and analyses enable high-quality direct or near-direct measurements of the turbulent fluxes and dissipation rates, and (c) the remaining challenges include the interaction of waves and currents with the erodible seabed, the impact of layer-scale two- and three-dimensional instabilities, and the role of the bottom boundary layer in shelf-slope exchange.

  8. Lipid Supplement in the Cultural Condition Facilitates the Porcine iPSC Derivation through cAMP/PKA/CREB Signal Pathway

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2018-02-01

    Full Text Available Large numbers of lipids exist in the porcine oocytes and early embryos and have the positive effects on their development, suggesting that the lipids may play an important role in pluripotency establishment and maintenance in pigs. However, the effects of lipids and their metabolites, such as fatty acids on reprogramming and the pluripotency gene expression of porcine-induced pluripotent stem cells (iPSCs, are unclear. Here, we generated the porcine iPSCs that resemble the mouse embryonic stem cells (ESCs under lipid and fatty-acid-enriched cultural conditions (supplement of AlbuMAX. These porcine iPSCs show positive for the ESCs pluripotency markers and have the differentiation abilities to all three germ layers, and importantly, have the capability of aggregation into the inner cell mass (ICM of porcine blastocysts. We further confirmed that lipid and fatty acid enriched condition can promote the cell proliferation and improve reprogramming efficiency by elevating cAMP levels. Interestingly, this lipids supplement promotes mesenchymal–epithelial transition (MET through the cAMP/PKA/CREB signal pathway and upregulates the E-cadherin expression during porcine somatic cell reprogramming. The lipids supplement also makes a contribution to lipid droplets accumulation in the porcine iPSCs that resemble porcine preimplantation embryos. These findings may facilitate understanding of the lipid metabolism in porcine iPSCs and lay the foundation of bona fide porcine embryonic stem cell derivation.

  9. Spastin binds to lipid droplets and affects lipid metabolism.

    Directory of Open Access Journals (Sweden)

    Chrisovalantis Papadopoulos

    2015-04-01

    Full Text Available Mutations in SPAST, encoding spastin, are the most common cause of autosomal dominant hereditary spastic paraplegia (HSP. HSP is characterized by weakness and spasticity of the lower limbs, owing to progressive retrograde degeneration of the long corticospinal axons. Spastin is a conserved microtubule (MT-severing protein, involved in processes requiring rearrangement of the cytoskeleton in concert to membrane remodeling, such as neurite branching, axonal growth, midbody abscission, and endosome tubulation. Two isoforms of spastin are synthesized from alternative initiation codons (M1 and M87. We now show that spastin-M1 can sort from the endoplasmic reticulum (ER to pre- and mature lipid droplets (LDs. A hydrophobic motif comprised of amino acids 57 through 86 of spastin was sufficient to direct a reporter protein to LDs, while mutation of arginine 65 to glycine abolished LD targeting. Increased levels of spastin-M1 expression reduced the number but increased the size of LDs. Expression of a mutant unable to bind and sever MTs caused clustering of LDs. Consistent with these findings, ubiquitous overexpression of Dspastin in Drosophila led to bigger and less numerous LDs in the fat bodies and increased triacylglycerol levels. In contrast, Dspastin overexpression increased LD number when expressed specifically in skeletal muscles or nerves. Downregulation of Dspastin and expression of a dominant-negative variant decreased LD number in Drosophila nerves, skeletal muscle and fat bodies, and reduced triacylglycerol levels in the larvae. Moreover, we found reduced amount of fat stores in intestinal cells of worms in which the spas-1 homologue was either depleted by RNA interference or deleted. Taken together, our data uncovers an evolutionarily conserved role of spastin as a positive regulator of LD metabolism and open up the possibility that dysfunction of LDs in axons may contribute to the pathogenesis of HSP.

  10. Long-term impairment of the lacrimal glands after radioiodine therapy: a cross-sectional study

    International Nuclear Information System (INIS)

    Zettinig, Georg; Fueger, Barbara J.; Pirich, Christian; Dudczak, Robert; Hanselmayer, Georg; Nepp, Johannes; Hofmann, Andrea

    2002-01-01

    Impairment of the lacrimal glands after external radiation has been well documented, but there are only a few reports on the effects of radioiodine therapy on the lacrimal glands. Long-term effects of high-dose radioiodine therapy on tear secretion have not previously been studied. We investigated 175 eyes of 88 patients with a history of radioiodine therapy for thyroid carcinoma (68 females, 20 males; mean age 55±16 years, range 17-81 years) and compared them with a sex- and age-matched control group (n=39). All patients had been given at least 2.96 GBq iodine-131 (maximal administered activity 22.3 GBq 131 I). An ophthalmological investigation was performed 64±71 months (range 3-317 months) after initial radioiodine therapy by a single ophthalmologist. Lacrimal gland function was evaluated with three different function tests. External eye morphology was considered, and detailed ophthalmological history-taking was performed. Patients with factors known to affect lacrimal gland function (contact lenses, autoimmune disorders, history of additional radiation exposure) were excluded from the study. A total of 81 patients (92%) had at least one abnormal function test indicating impaired lacrimal gland function. Schirmer's tear test was decreased (<10 mm/5 min) in 47 of the 88 patients and definitely abnormal (<5 mm/5 min) in 35 patients. A tear film break-up time of <10 s was found in 78 patients, and 62 patients had a definitely abnormal break-up time of <5 s. The lacrimal lipid layer was impaired in 43 patients. The function tests were all significantly altered in the study group as compared with the controls (P<0.005, P<0.001, P<0.001, respectively). Both subjective symptoms of dry eye (P<0.01) and changes in the external eye morphology (P<0.001) were significantly more prevalent in the study group. Our findings suggest that in the majority of patients, lacrimal gland function may be permanently impaired after high-dose radioiodine therapy. All three layers of the

  11. Elastin aging and lipid oxidation products in human aorta

    Directory of Open Access Journals (Sweden)

    Kamelija Zarkovic

    2015-04-01

    Full Text Available Vascular aging is associated with structural and functional modifications of the arteries, and by an increase in arterial wall thickening in the intima and the media, mainly resulting from structural modifications of the extracellular matrix (ECM components. Among the factors known to accumulate with aging, advanced lipid peroxidation end products (ALEs are a hallmark of oxidative stress-associated diseases such as atherosclerosis. Aldehydes generated from the peroxidation of polyunsaturated fatty acids (PUFA, (4-hydroxynonenal, malondialdehyde, acrolein, form adducts on cellular proteins, leading to a progressive protein dysfunction with consequences in the pathophysiology of vascular aging. The contribution of these aldehydes to ECM modification is not known. This study was carried out to investigate whether aldehyde-adducts are detected in the intima and media in human aorta, whether their level is increased in vascular aging, and whether elastin fibers are a target of aldehyde-adduct formation. Immunohistological and confocal immunofluorescence studies indicate that 4-HNE-histidine-adducts accumulate in an age-related manner in the intima, media and adventitia layers of human aortas, and are mainly expressed in smooth muscle cells. In contrast, even if the structure of elastin fiber is strongly altered in the aged vessels, our results show that elastin is not or very poorly modified by 4-HNE. These data indicate a complex role for lipid peroxidation and in particular for 4-HNE in elastin homeostasis, in the vascular wall remodeling during aging and atherosclerosis development.

  12. Radiation destruction of vitamin A in lipid solvents

    International Nuclear Information System (INIS)

    Snauwaert, F.; Maes, E.; Tobback, P.; Bhushan, B.

    1978-01-01

    The radiation response of vitamin A alcohol and its acetate derivative was compared in different lipid solvents. In all the solvents vitamin A alcohol exhibited a much higher radiation sensitivity than its ester counterpart. The nature of the solvent and the initial concentration was found to have a great influence on the extent of radiation degradation of vitamin A alcohol. In contrast to a high radiolability in non-polar solvents, vitamin A alcohol exhibited a remarkable stability in isopropanol. In addition, in isopropanol the G(-) relationship with radiation dose showed a reverse trend to that observed for other solvents. A thin-layer chromatographic procedure was developed for separation of the radiation degradation products. (author)

  13. Radiochemical methods for studying lipase-catalyzed interesterification of lipids

    International Nuclear Information System (INIS)

    Schuch, R.; Mukherjee, K.D.

    1987-01-01

    Reactions involving lipase-catalyzed interesterification of lipids, which are of commendable interest in biotechnology, have been monitored and assayed by radiochemical methods using 14 C-labeled substrates. Medium chain (C 12 plus C 14 ) triacylglycerols were reacted in the presence of an immobilized lipase from Mucor miehei and hexane at 45 0 C with methyl [1- 14 C]oleate, [1- 14 C]oleic acid, [carboxyl- 14 C]trioleoylglycerol, [1- 14 C]octadecenyl alcohol, and [U- 14 C]glycerol, each of known specific activity. The reactions were monitored and the rate of interesterification determined by radio thin layer chromatography from the incorporation of radioactivity into acyl moieties of triacylglycerols (from methyl oleate, oleic acid, and trioleoylglycerol), alkyl moieties of wax esters (from octadecenyl alcohol), and into glycerol backbone of monoacylglycerols and diacylglycerols (from glycerol). (orig.)

  14. Combined effects of headgroup charge and tail unsaturation of lipids on lateral organization and diffusion of lipids in model biomembranes

    International Nuclear Information System (INIS)

    Chen Xiao-Jie; Liang Qing

    2017-01-01

    Lateral organization and dynamics of lipids in plasma membranes are crucial for several cellular processes such as signal transduction across the membrane and still remain elusive. In this paper, using coarse-grained molecular dynamics simulation, we theoretically study the combined effects of headgroup charge and tail unsaturation of lipids on the lateral organization and diffusion of lipids in ternary lipid bilayers. In neutral ternary lipid bilayers composed of saturated lipids, unsaturated lipids, and cholesterols, under the conditions of given temperature and components, the main factor for the phase separation is the unsaturation of unsaturated lipids and the bilayers can be separated into liquid-ordered domains enriched in saturated lipids and cholesterols and liquid-disordered domains enriched in unsaturated lipids. Once the headgroup charge is introduced, the electrostatic repulsion between the negatively charged lipid headgroups will increase the distance between the charged lipids. We find that the lateral organization and diffusion of the lipids in the (partially) charged ternary lipid bilayers are determined by the competition between the headgroup charge and the unsaturation of the unsaturated lipids. In the bilayers containing unsaturated lipids with lower unsaturation, the headgroup charge plays a crucial role in the lateral organization and diffusion of lipids. The headgroup charge may make the lipid domains unstable and even can suppress phase separation of the lipids in some systems. However, in the bilayers containing highly unsaturated lipids, the lateral organization and diffusion of lipids are mainly dominated by the unsaturation of the unsaturated lipids. This work may provide some theoretical insights into understanding the formation of nanosized domains and lateral diffusion of lipids in plasma membranes. (paper)

  15. Radiation-induced lipid peroxidation: influence of oxygen concentration and membrane lipid composition

    International Nuclear Information System (INIS)

    Wolters, H.; Tilburg, C.A.M. van; Konings, A.W.T.

    1987-01-01

    Radiation -induced lipid peroxidation phospholipid liposomes was investigated in terms of its dependence on lipid composition and oxygen concentration. Non-peroxidizable lipid incorporated in the liposomes reduced the rate of peroxidation of the peroxidizable phospholipid acyl chains, possibly by restricting the length of chain reactions. The latter effect is believed to be caused by interference of the non-peroxidizable lipids in the bilayer. At low oxygen concentration lipid peroxidation was reduced. The cause of this limited peroxidation may be a reduced number of radical initiation reactions possibly involving oxygen-derived superoxide radicals. Killing of proliferating mammalian cells, irradiated at oxygen concentrations ranging from 0 to 100%, appeared to be independent of the concentration of peroxidizable phospholipids in the cell membranes. This indicates that lipid peroxidation is not the determining process in radiation-induced reproductive cell death. (author)

  16. Lipid measures and cardiovascular disease prediction

    NARCIS (Netherlands)

    van Wijk, D.F.; Stroes, E.S.G.; Kastelein, J.J.P.

    2009-01-01

    Traditional lipid measures are the cornerstone of risk assessment and treatment goals in cardiovascular prevention. Whereas the association between total, LDL-, HDL-cholesterol and cardiovascular disease risk has been generally acknowledged, the rather poor capacity to distinguish between patients

  17. Novel approaches to lipid-lowering therapy

    African Journals Online (AJOL)

    lines, ezetimibe is recommended as an add-on therapy for patients on ... 2 Carbohydrate and Lipid Metabolism Research Unit and Division of Endocrinology and Metabolism ... acting at the level of protein translation via RNA interference in the.

  18. Artificial Lipid Membranes: Past, Present, and Future.

    Science.gov (United States)

    Siontorou, Christina G; Nikoleli, Georgia-Paraskevi; Nikolelis, Dimitrios P; Karapetis, Stefanos K

    2017-07-26

    The multifaceted role of biological membranes prompted early the development of artificial lipid-based models with a primary view of reconstituting the natural functions in vitro so as to study and exploit chemoreception for sensor engineering. Over the years, a fair amount of knowledge on the artificial lipid membranes, as both, suspended or supported lipid films and liposomes, has been disseminated and has helped to diversify and expand initial scopes. Artificial lipid membranes can be constructed by several methods, stabilized by various means, functionalized in a variety of ways, experimented upon intensively, and broadly utilized in sensor development, drug testing, drug discovery or as molecular tools and research probes for elucidating the mechanics and the mechanisms of biological membranes. This paper reviews the state-of-the-art, discusses the diversity of applications, and presents future perspectives. The newly-introduced field of artificial cells further broadens the applicability of artificial membranes in studying the evolution of life.

  19. Homogenization of the lipid profile values.

    Science.gov (United States)

    Pedro-Botet, Juan; Rodríguez-Padial, Luis; Brotons, Carlos; Esteban-Salán, Margarita; García-Lerín, Aurora; Pintó, Xavier; Lekuona, Iñaki; Ordóñez-Llanos, Jordi

    Analytical reports from the clinical laboratory are essential to guide clinicians about what lipid profile values should be considered altered and, therefore, require intervention. Unfortunately, there is a great heterogeneity in the lipid values reported as "normal, desirable, recommended or referenced" by clinical laboratories. This can difficult clinical decisions and be a barrier to achieve the therapeutic goals for cardiovascular prevention. A recent international recommendation has added a new heterogeneity factor for the interpretation of lipid profile, such as the possibility of measuring it without previous fasting. All this justifies the need to develop a document that adapts the existing knowledge to the clinical practice of our health system. In this regard, professionals from different scientific societies involved in the measurement and use of lipid profile data have developed this document to establish recommendations that facilitate their homogenization. Copyright © 2017. Publicado por Elsevier España, S.L.U.

  20. Lipid Bilayer Formation on Organic Electronic Materials

    KAUST Repository

    Zhang, Yi; Wustoni, Shofarul; Savva, Achilleas; Giovannitti, Alexander; McCulloch, Iain; Inal, Sahika

    2018-01-01

    The lipid bilayer is the elemental structure of cell membrane, forming a stable barrier between the interior and exterior of the cell while hosting membrane proteins that enable selective transport of biologically important compounds and cellular

  1. Normal and abnormal lipid and lipoprotein metabolism

    African Journals Online (AJOL)

    2009-03-20

    Mar 20, 2009 ... This article focuses on lipid and lipoprotein metabolism and introduces a range of genetic ... spherical structures that are suspended in the plasma and whose ..... atherosclerosis. Table II suggests a simple classification of.

  2. A STUDY OF LIPID PROFILE IN PREDIABETES

    Directory of Open Access Journals (Sweden)

    Manoj

    2016-06-01

    Full Text Available BACKGROUND Lipid abnormalities are common in diabetes mellitus and play an important role in acceleration of atherosclerosis leading to increased cardiovascular diseases. Due to increasing burden of diabetes, it is becoming important to identify dyslipidaemia in high-risk state for diabetes especially prediabetes so that early intervention can reduce cardiovascular risk. AIM To study lipid profile in prediabetes individuals. METHODS This study was a cross-sectional case control study which included 107 prediabetes and 101 healthy controls. Lipid profile of prediabetes and controls were measured and statistically analysed. RESULT Total cholesterol, LDL, triglycerides, VLDL, TG/HDL ratio, and LDL/HDL ratio were significantly high whereas HDL was significantly low in prediabetes subjects as compared to controls. CONCLUSION This study showed significant lipid abnormalities in prediabetes subjects. Because of these they are at high risk of developing atherosclerotic cardiovascular diseases. Therefore, proper screening and appropriate therapy of these conditions becomes important.

  3. Overview of Cholesterol and Lipid Disorders

    Science.gov (United States)

    ... Professor of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version ... Cholesterol and triglycerides are important ...

  4. Thyroid hormones and lipid phosphorus in mice

    Energy Technology Data Exchange (ETDEWEB)

    Thakare, U R; Ganatra, R D; Shah, D H [Bhabha Atomic Research Centre, Bombay (India). Radiation Medicine Centre

    1978-04-01

    In vivo studies in mice injected intravenously with /sup 125/I-triiodothyronine (T-3) showed a linear relationship between the uptake of the labelled hormone by the tissue and the lipid phosphorous content of the same tissue. However, studies with /sup 125/I-thyroxine failed to show a similar relationship between the lipid phosphorous content of the organ and the uptake of radioactive hormone by the same organ. In vitro studies using equilibrium dialysis technique with isolated lipid extracts of various organs and radioactive thyroid hormones (T-3 and T-4) did not show any relation between the lipid P and the uptake of labelled hormone. On the basis of the observed discrepancy between in vivo and in vitro studies, it is postulated that an organized lipoprotein structure at the cell membrane may be responsible for the entry of the thyroid hormones.

  5. Supramolecular protein immobilization on lipid bilayers

    NARCIS (Netherlands)

    Bosmans, R.P.G.; Hendriksen, W.E.; Verheijden, Mark Lloyd; Eelkema, R.; Jonkheijm, Pascal; van Esch, J.H.; Brunsveld, Luc

    2015-01-01

    Protein immobilization on surfaces, and on lipid bilayers specifically, has great potential in biomolecular and biotechnological research. Of current special interest is the immobilization of proteins using supramolecular noncovalent interactions. This allows for a reversible immobilization and

  6. Assessing the nature of lipid raft membranes

    DEFF Research Database (Denmark)

    Niemelä, Perttu S; Ollila, Samuli; Hyvönen, Marja T

    2007-01-01

    of highly ordered lateral domains rich in sphingomyelin and cholesterol (CHOL). These domains, called functional lipid rafts, have been suggested to take part in a variety of dynamic cellular processes such as membrane trafficking, signal transduction, and regulation of the activity of membrane proteins......-scale simulations to elucidate the properties of ternary raft mixtures with CHOL, palmitoylsphingomyelin (PSM), and palmitoyloleoylphosphatidylcholine. We simulate two bilayers of 1,024 lipids for 100 ns in the liquid-ordered phase and one system of the same size in the liquid-disordered phase. The studies provide...... heterogeneity more difficult. The findings reveal aspects of the role of favored (specific) lipid-lipid interactions within rafts and clarify the prominent role of CHOL in altering the properties of the membrane locally in its neighborhood. Also, we show that the presence of PSM and CHOL in rafts leads...

  7. Voltage-gated lipid ion channels

    DEFF Research Database (Denmark)

    Blicher, Andreas; Heimburg, Thomas Rainer

    2013-01-01

    Synthetic lipid membranes can display channel-like ion conduction events even in the absence of proteins. We show here that these events are voltage-gated with a quadratic voltage dependence as expected from electrostatic theory of capacitors. To this end, we recorded channel traces and current...... histograms in patch-experiments on lipid membranes. We derived a theoretical current-voltage relationship for pores in lipid membranes that describes the experimental data very well when assuming an asymmetric membrane. We determined the equilibrium constant between closed and open state and the open...... probability as a function of voltage. The voltage-dependence of the lipid pores is found comparable to that of protein channels. Lifetime distributions of open and closed events indicate that the channel open distribution does not follow exponential statistics but rather power law behavior for long open times...

  8. Improved characterization of EV preparations based on protein to lipid ratio and lipid properties.

    Directory of Open Access Journals (Sweden)

    Xabier Osteikoetxea

    Full Text Available In recent years the study of extracellular vesicles has gathered much scientific and clinical interest. As the field is expanding, it is becoming clear that better methods for characterization and quantification of extracellular vesicles as well as better standards to compare studies are warranted. The goal of the present work was to find improved parameters to characterize extracellular vesicle preparations. Here we introduce a simple 96 well plate-based total lipid assay for determination of lipid content and protein to lipid ratios of extracellular vesicle preparations from various myeloid and lymphoid cell lines as well as blood plasma. These preparations included apoptotic bodies, microvesicles/microparticles, and exosomes isolated by size-based fractionation. We also investigated lipid bilayer order of extracellular vesicle subpopulations using Di-4-ANEPPDHQ lipid probe, and lipid composition using affinity reagents to clustered cholesterol (monoclonal anti-cholesterol antibody and ganglioside GM1 (cholera toxin subunit B. We have consistently found different protein to lipid ratios characteristic for the investigated extracellular vesicle subpopulations which were substantially altered in the case of vesicular damage or protein contamination. Spectral ratiometric imaging and flow cytometric analysis also revealed marked differences between the various vesicle populations in their lipid order and their clustered membrane cholesterol and GM1 content. Our study introduces for the first time a simple and readily available lipid assay to complement the widely used protein assays in order to better characterize extracellular vesicle preparations. Besides differentiating extracellular vesicle subpopulations, the novel parameters introduced in this work (protein to lipid ratio, lipid bilayer order, and lipid composition, may prove useful for quality control of extracellular vesicle related basic and clinical studies.

  9. GPS-Lipid: a robust tool for the prediction of multiple lipid modification sites

    OpenAIRE

    Xie, Yubin; Zheng, Yueyuan; Li, Hongyu; Luo, Xiaotong; He, Zhihao; Cao, Shuo; Shi, Yi; Zhao, Qi; Xue, Yu; Zuo, Zhixiang; Ren, Jian

    2016-01-01

    As one of the most common post-translational modifications in eukaryotic cells, lipid modification is an important mechanism for the regulation of variety aspects of protein function. Over the last decades, three classes of lipid modifications have been increasingly studied. The co-regulation of these different lipid modifications is beginning to be noticed. However, due to the lack of integrated bioinformatics resources, the studies of co-regulatory mechanisms are still very limited. In this...

  10. Exogenous ether lipids predominantly target mitochondria

    DEFF Research Database (Denmark)

    Kuerschner, Lars; Richter, Doris; Hannibal-Bach, Hans Kristian

    2012-01-01

    Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high......, accumulated to mitochondria and induced morphological changes and cellular apoptosis. These data indicate that edelfosine could exert its pro-apoptotic power by targeting and damaging mitochondria and thereby inducing cellular apoptosis. In general, this study implies an important role of mitochondria...

  11. Biosynthesis of archaeal membrane ether lipids

    Directory of Open Access Journals (Sweden)

    Samta eJain

    2014-11-01

    Full Text Available A vital function of the cell membrane in all living organism is to maintain the membrane permeability barrier and fluidity. The composition of the phospholipid bilayer is distinct in archaea when compared to bacteria and eukarya. In archaea, isoprenoid hydrocarbon side chains are linked via an ether bond to the sn-glycerol-1-phosphate backbone. In bacteria and eukarya on the other hand, fatty acid side chains are linked via an ester bond to the sn-glycerol-3-phosphate backbone. The polar head groups are globally shared in the three domains of life. The unique membrane lipids of archaea have been implicated not only in the survival and adaptation of the organisms to extreme environments but also to form the basis of the membrane composition of the last universal common ancestor (LUCA. In nature, a diverse range of archaeal lipids is found, the most common are the diether (or archaeol and the tetraether (or caldarchaeol lipids that form a monolayer. Variations in chain length, cyclization and other modifications lead to diversification of these lipids. The biosynthesis of these lipids is not yet well understood however progress in the last decade has led to a comprehensive understanding of the biosynthesis of archaeol. This review describes the current knowledge of the biosynthetic pathway of archaeal ether lipids; insights on the stability and robustness of archaeal lipid membranes; and evolutionary aspects of the lipid divide and the last universal common ancestor LUCA. It examines recent advances made in the field of pathway reconstruction in bacteria.

  12. Lipid Microarray Biosensor for Biotoxin Detection.

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anup K.; Throckmorton, Daniel J.; Moran-Mirabal, Jose C.; Edel, Joshua B.; Meyer, Grant D.; Craighead, Harold G.

    2006-05-01

    We present the use of micron-sized lipid domains, patterned onto planar substrates and within microfluidic channels, to assay the binding of bacterial toxins via total internal reflection fluorescence microscopy (TIRFM). The lipid domains were patterned using a polymer lift-off technique and consisted of ganglioside-populated DSPC:cholesterol supported lipid bilayers (SLBs). Lipid patterns were formed on the substrates by vesicle fusion followed by polymer lift-off, which revealed micron-sized SLBs containing either ganglioside GT1b or GM1. The ganglioside-populated SLB arrays were then exposed to either Cholera toxin subunit B (CTB) or Tetanus toxin fragment C (TTC). Binding was assayed on planar substrates by TIRFM down to 1 nM concentration for CTB and 100 nM for TTC. Apparent binding constants extracted from three different models applied to the binding curves suggest that binding of a protein to a lipid-based receptor is strongly affected by the lipid composition of the SLB and by the substrate on which the bilayer is formed. Patterning of SLBs inside microfluidic channels also allowed the preparation of lipid domains with different compositions on a single device. Arrays within microfluidic channels were used to achieve segregation and selective binding from a binary mixture of the toxin fragments in one device. The binding and segregation within the microfluidic channels was assayed with epifluorescence as proof of concept. We propose that the method used for patterning the lipid microarrays on planar substrates and within microfluidic channels can be easily adapted to proteins or nucleic acids and can be used for biosensor applications and cell stimulation assays under different flow conditions. KEYWORDS. Microarray, ganglioside, polymer lift-off, cholera toxin, tetanus toxin, TIRFM, binding constant.4

  13. Lipoprotein lipase: genetics, lipid uptake, and regulation.

    Science.gov (United States)

    Merkel, Martin; Eckel, Robert H; Goldberg, Ira J

    2002-12-01

    Lipoprotein lipase (LPL) regulates the plasma levels of triglyceride and HDL. Three aspects are reviewed. 1) Clinical implications of human LPL gene variations: common mutations and their effects on plasma lipids and coronary heart disease are discussed. 2) LPL actions in the nervous system, liver, and heart: the discussion focuses on LPL and tissue lipid uptake. 3) LPL gene regulation: the LPL promoter and its regulatory elements are described.

  14. Rapid modification of retroviruses using lipid conjugates

    International Nuclear Information System (INIS)

    Mukherjee, Nimisha G; Le Doux, Joseph M; Andrew Lyon, L

    2009-01-01

    Methods are needed to manipulate natural nanoparticles. Viruses are particularly interesting because they can act as therapeutic cellular delivery agents. Here we examine a new method for rapidly modifying retroviruses that uses lipid conjugates composed of a lipid anchor (1,2-distearoyl-sn-glycero-3-phosphoethanolamine), a polyethylene glycol chain, and biotin. The conjugates rapidly and stably modified retroviruses and enabled them to bind streptavidin. The implication of this work for modifying viruses for gene therapy and vaccination protocols is discussed.

  15. Preservation of Lipid Biomarkers Under Prolonged and Extreme Hyperaridity in Atacama Desert Soils

    Science.gov (United States)

    Wilhelm, Mary Beth

    2015-01-01

    Molecular biomarkers are the most direct biosignatures of life on early Earth and a key target in the search for life on Mars. Lipid biomarkers are of particular interest given their ability to survive oxidative degradation and record microbial presence and activity of microorganisms that occurred billions of years ago (Eigenbrode, 2008). Environmental conditions that suspend biotic and abiotic degradative processes prior to lithification can lead to enhanced biomolecular preservation over geological time-scales. The hyperarid core of the Atacama Desert in northern Chile offers a unique environment to investigate lipid biomarker taphonomy under extreme and prolonged dryness. We investigated the accumulation and degree of preservation of lipid biomarkers in million-year-old hyperarid soils where primarily abiotic conditions influence their taphonomy. Soils were extracted and free and membrane bound lipids were analyzed across a vertical profile of 2.5 meters in the Yungay hyper-arid core of the Atacama Desert. Due to the extremely low inventory of biomass in Atacama soils, samples were collected by scientists wearing cleanroom suits to minimize anthropogenic contamination during sampling. Fatty acids were found to be well preserved in Yungay soils, and were most abundant in the clay-rich soils at approx.2 m depth (approx.750 ng of fatty acid methyl ester/g of soil). These buried clays layers were fluvially deposited approximately 2 million years ago, and have been excluded from exposure to rainwater and modern surficial processes since their emplacement (Ewing et al., 2008). Monocarboxylic fatty acid, monohydroxy fatty acid, glycerol tetraether, and n-alkane hydrocarbon content was found to change with depth. Lipid biomarker content in deeper soil layers is suggestive of soils having been formed at a time when environmental conditions were capable of supporting active microbial communities and plants. In short, total lipid extracts reveal a remarkable degree of

  16. Preservation of Lipid Biomarkers Under Prolonged and Extreme Hyperaridity in Atacama Desert Soils

    Science.gov (United States)

    Wilhelm, M. B.; Davila, A. F.; Eigenbrode, J. L.; Parenteau, M. N.; Jahnke, L. L.; Summons, R. E.; Liu, X.; Wray, J. J.; Stamos, B.; O'Reilly, S. S.; Williams, A. J.

    2015-12-01

    Molecular biomarkers are the most direct biosignatures of life on early Earth and a key target in the search for life on Mars. Lipid biomarkers are of particular interest given their ability to survive oxidative degradation and record microbial presence and activity of microorganisms that occurred billions of years ago (Eigenbrode, 2008). Environmental conditions that suspend biotic and abiotic degradative processes prior to lithification can lead to enhanced biomolecular preservation over geological time-scales. The hyperarid core of the Atacama Desert in northern Chile offers a unique environment to investigate lipid biomarker taphonomy under extreme and prolonged dryness. We investigated the accumulation and degree of preservation of lipid biomarkers in million-year-old hyperarid soils where primarily abiotic conditions influence their taphonomy. Soils were extracted and free and membrane bound lipids were analyzed across a vertical profile of 2.5 meters in the Yungay hyper-arid core of the Atacama Desert. Due to the extremely low inventory of biomass in Atacama soils, samples were collected by scientists wearing cleanroom suits to minimize anthropogenic contamination during sampling. Fatty acids were found to be well preserved in Yungay soils, and were most abundant in the clay-rich soils at ~2 m depth (~750 ng of fatty acid methyl ester/g of soil). These buried clays layers were fluvially deposited approximately 2 million years ago, and have been excluded from exposure to rainwater and modern surficial processes since their emplacement (Ewing et al., 2008). Monocarboxylic fatty acid, monohydroxy fatty acid, glycerol tetraether, and n-alkane hydrocarbon content was found to change with depth. Lipid biomarker content in deeper soil layers is suggestive of soils having been formed at a time when environmental conditions were capable of supporting active microbial communities and plants. In short, total lipid extracts reveal a remarkable degree of lipid biomarker

  17. PENGEMBANGAN SISTEM NANOSTRUCTURED LIPID CARRIERS (NLC) MELOXICAM DENGAN LIPID MONOSTEARIN DAN MIGLYOL 808 MENGGUNAKAN METODE EMULSIFIKASI

    OpenAIRE

    Rahmi Annisa; Esti Hendradi; Dewi Melani

    2016-01-01

    The aim this study was to determine the effect of Monostearin and Miglyol 808 lipid ratio in NLC system formulation resulting in physicochemical characteristics, release rate, and penetration rate. The NLC making was done by using emulsification method. In the formulation of NLC meloxicam, 3 different lipid ratios were used, including ratios of 6:4, 7:3, 8:2.  Meloxicam served as active ingredient, monostearin served as solid lipid, miglyol 808 served as a liquid lipid, and tween 80 was surfa...

  18. Lipid stability in meat and meat products.

    Science.gov (United States)

    Morrissey, P A; Sheehy, P J; Galvin, K; Kerry, J P; Buckley, D J

    1998-01-01

    Lipid oxidation is one of the main factors limiting the quality and acceptability of meats and meat products. Oxidative damage to lipids occurs in the living animal because of an imbalance between the production of reactive oxygen species and the animal's defence mechanisms. This may be brought about by a high intake of oxidized lipids or poly-unsaturated fatty acids, or a low intake of nutrients involved in the antioxidant defence system. Damage to lipids may be accentuated in the immediate post-slaughter period and, in particular, during handling, processing, storage and cooking. In recent years, pressure to reduce artificial additive use in foods has led to attempts to increase meat stability by dietary strategies. These include supplementation of animal diets with vitamin E, ascorbic acid, or carotenoids, or withdrawal of trace mineral supplements. Dietary vitamin E supplementation reduces lipid and myoglobin oxidation, and, in certain situations, drip losses in meats. However, vitamin C supplementation appears to have little, if any, beneficial effects on meat stability. The effect of feeding higher levels of carotenoids on meat stability requires further study. Some studies have demonstrated that reducing the iron and copper content of feeds improves meat stability. Post-slaughter carnosine addition may be an effective means of improving lipid stability in processed meats, perhaps in combination with dietary vitamin E supplementation.

  19. LIPID SYNTHESIS, INTRACELLULAR TRANSPORT, AND SECRETION

    Science.gov (United States)

    Stein, Olga; Stein, Yechezkiel

    1967-01-01

    In the mammary glands of lactating albino mice injected intravenously with 9, 10-oleic acid-3H or 9, 10-palmitic acid-3H, it has been shown that the labeled fatty acids are incorporated into mammary gland glycerides. The labeled lipid in the mammary gland 1 min after injection was in esterified form (> 95%), and the radioautographic reaction was seen over the rough endoplasmic reticulum and over lipid droplets, both intracellular and intraluminal. At 10–60 min after injection, the silver grains were concentrated predominantly over lipid droplets. There was no concentration of radioactivity over the granules in the Golgi apparatus, at any time interval studied. These findings were interpreted to indicate that after esterification of the fatty acid into glycerides in the rough endoplasmic reticulum an in situ aggregation of lipid occurs, with acquisition of droplet form. The release of the lipid into the lumen proceeds directly and not through the Golgi apparatus, in contradistinction to the mode of secretion of casein in the mammary gland or of lipoprotein in the liver. The presence of strands of endoplasmic reticulum attached to intraluminal lipid droplets provides a structural counterpart to the milk microsomes described in ruminant milk. PMID:6033535

  20. Lipid Droplets and Mycobacterium leprae Infection

    Science.gov (United States)

    Elamin, Ayssar A.; Stehr, Matthias; Singh, Mahavir

    2012-01-01

    Leprosy is a chronic infectious disease and is a major source of morbidity in developing countries. Leprosy is caused by the obligate intracellular bacterium Mycobacterium leprae, which infects as primary target Schwann cells. Lepromatous leprosy exhibits multiple lesions of the skin, eyes, nerves, and lymph nodes. The sites of infection are characterized by the presence of foamy macrophages, fully packed with lipid droplets (LDs), which are induced by M. leprae. In the last years, it has become evident that M. tuberculosis imports lipids from foamy macrophages and is dependent on fatty acids for growth in infected macrophages. M. leprae seems to have similar mechanisms for scavenging lipids from the host. But due to the inability to culture M. leprae on laboratory media, research progresses only slowly. However, in the last years, substantial progress has been made in the field of lipid metabolism in M. leprae. Herein, we will present and summarize the lipid droplets formation and the metabolism of lipids during M. leprae infection. PMID:23209912

  1. Lipid Raft, Regulator of Plasmodesmal Callose Homeostasis

    Directory of Open Access Journals (Sweden)

    Arya Bagus Boedi Iswanto

    2017-04-01

    Full Text Available Abstract: The specialized plasma membrane microdomains known as lipid rafts are enriched by sterols and sphingolipids. Lipid rafts facilitate cellular signal transduction by controlling the assembly of signaling molecules and membrane protein trafficking. Another specialized compartment of plant cells, the plasmodesmata (PD, which regulates the symplasmic intercellular movement of certain molecules between adjacent cells, also contains a phospholipid bilayer membrane. The dynamic permeability of plasmodesmata (PDs is highly controlled by plasmodesmata callose (PDC, which is synthesized by callose synthases (CalS and degraded by β-1,3-glucanases (BGs. In recent studies, remarkable observations regarding the correlation between lipid raft formation and symplasmic intracellular trafficking have been reported, and the PDC has been suggested to be the regulator of the size exclusion limit of PDs. It has been suggested that the alteration of lipid raft substances impairs PDC homeostasis, subsequently affecting PD functions. In this review, we discuss the substantial role of membrane lipid rafts in PDC homeostasis and provide avenues for understanding the fundamental behavior of the lipid raft–processed PDC.

  2. Lipid Raft, Regulator of Plasmodesmal Callose Homeostasis.

    Science.gov (United States)

    Iswanto, Arya Bagus Boedi; Kim, Jae-Yean

    2017-04-03

    A bstract: The specialized plasma membrane microdomains known as lipid rafts are enriched by sterols and sphingolipids. Lipid rafts facilitate cellular signal transduction by controlling the assembly of signaling molecules and membrane protein trafficking. Another specialized compartment of plant cells, the plasmodesmata (PD), which regulates the symplasmic intercellular movement of certain molecules between adjacent cells, also contains a phospholipid bilayer membrane. The dynamic permeability of plasmodesmata (PDs) is highly controlled by plasmodesmata callose (PDC), which is synthesized by callose synthases (CalS) and degraded by β-1,3-glucanases (BGs). In recent studies, remarkable observations regarding the correlation between lipid raft formation and symplasmic intracellular trafficking have been reported, and the PDC has been suggested to be the regulator of the size exclusion limit of PDs. It has been suggested that the alteration of lipid raft substances impairs PDC homeostasis, subsequently affecting PD functions. In this review, we discuss the substantial role of membrane lipid rafts in PDC homeostasis and provide avenues for understanding the fundamental behavior of the lipid raft-processed PDC.

  3. Affinity of serum apolipoproteins for lipid monolayers

    International Nuclear Information System (INIS)

    Ibdah, J.A.

    1987-01-01

    The effects of lipid composition and packing as well as the structure of the protein on the affinities of apolipoproteins for lipid monolayers have been investigated. The adsorption of 14 C-reductively methylated human apolipoproteins A-I and A-II at saturating subphase concentrations to monolayers prepared with synthetic lipids or lipoprotein surface lipids spread at various initial surface pressures has been studied. The adsorption of apolipoproteins is monitored by following the surface radioactivity using a gas flow counter and Wilhelmy plate, respectively. The physical states of the lipid monolayers are evaluated by measurement of the surface pressure-molecular area isotherms using a Langmuir-Adam surface balance. The probable helical regions in various apolipoproteins have been predicted using a secondary structure analysis computer program. The mean residue hydrophobicity and mean residue hydrophobic moment for the predicted helical segments have been calculated. The surface properties of synthetic peptides which are amphipathic helix analogs have been investigated at the air-water and lipid-water interfaces

  4. Lipids of Parasitic and Saprophytic Leptospires

    Science.gov (United States)

    Johnson, R. C.; Livermore, B. P.; Walby, Judith K.; Jenkin, H. M.

    1970-01-01

    The lipid composition of five parasitic and six saprophytic leptospires was compared. Lipids comprise 18 to 26% of the dry weight of the cells after chloroform-methanol extraction. No residual (bound) lipid was found after acid or alkaline hydrolysis of the extracted residue. The total lipid was composed of 60 to 70% phospholipid, and the remaining lipid was free fatty acids. The phospholipid fraction contained phosphatidylethanolamine as the major component, and phosphatidylglycerol and diphosphatidylglycerol were minor components with traces of lysophatidylethanolamine sometimes found. The major fatty acids of leptospires were hexadecanoic, hexadecenoic, and octadecenoic acids. Both the unusual cis-11-hexadecenoic acid and the more common cis-9-hexadecenoic acid were synthesized by the leptospires. Neither the parasitic nor the saprophytic leptospires can chain elongate fatty acids. However, they were capable of β-oxidation of fatty acids. Both groups of leptospires desaturate fatty acids by an aerobic pathway. When the parasite canicola was cultivated on octadecanoic acid, 87% of the hexadecenoic acid was the 11 isomer, whereas the saprophyte semeranga consisted of 10% of this isomer. In addition, the saprophytic leptospires contained more tetradecanoic acid than the parasites. No differences were observed in the lipid composition of virulent and avirulent strains of canicola. PMID:16557833

  5. Microalgal lipids biochemistry and biotechnological perspectives.

    Science.gov (United States)

    Bellou, Stamatia; Baeshen, Mohammed N; Elazzazy, Ahmed M; Aggeli, Dimitra; Sayegh, Fotoon; Aggelis, George

    2014-12-01

    In the last few years, there has been an intense interest in using microalgal lipids in food, chemical and pharmaceutical industries and cosmetology, while a noteworthy research has been performed focusing on all aspects of microalgal lipid production. This includes basic research on the pathways of solar energy conversion and on lipid biosynthesis and catabolism, and applied research dealing with the various biological and technical bottlenecks of the lipid production process. In here, we review the current knowledge in microalgal lipids with respect to their metabolism and various biotechnological applications, and we discuss potential future perspectives. The committing step in fatty acid biosynthesis is the carboxylation of acetyl-CoA to form malonyl-CoA that is then introduced in the fatty acid synthesis cycle leading to the formation of palmitic and stearic acids. Oleic acid may also be synthesized after stearic acid desaturation while further conversions of the fatty acids (i.e. desaturations, elongations) occur after their esterification with structural lipids of both plastids and the endoplasmic reticulum. The aliphatic chains are also used as building blocks for structuring storage acylglycerols via the Kennedy pathway. Current research, aiming to enhance lipogenesis in the microalgal cell, is focusing on over-expressing key-enzymes involved in the earlier steps of the pathway of fatty acid synthesis. A complementary plan would be the repression of lipid catabolism by down-regulating acylglycerol hydrolysis and/or β-oxidation. The tendency of oleaginous microalgae to synthesize, apart from lipids, significant amounts of other energy-rich compounds such as sugars, in processes competitive to lipogenesis, deserves attention since the lipid yield may be considerably increased by blocking competitive metabolic pathways. The majority of microalgal production occurs in outdoor cultivation and for this reason biotechnological applications face some difficulties

  6. Ionizing radiation and lipid peroxidation in human body

    International Nuclear Information System (INIS)

    Giubileo, Gianfranco

    1997-07-01

    Lipids are organic compounds constituting the living cells. Lipid molecules can be disassembled through peroxidative pathways and hydrocarbons can be bred as end-product of lipid peroxidation in vivo. Lipid peroxidation can be started by an indirect effect of ionizing radiation. So a radioinduced cellular damage in human body can be detected by monitoring the production of specific hydrocarbons

  7. Protein-lipid interactions: from membrane domains to cellular networks

    National Research Council Canada - National Science Library

    Tamm, Lukas K

    2005-01-01

    ... membranes is the lipid bilayer. Embedded in the fluid lipid bilayer are proteins of various shapes and traits. This volume illuminates from physical, chemical and biological angles the numerous - mostly quite weak - interactions between lipids, proteins, and proteins and lipids that define the delicate, highly dynamic and yet so stable fabri...

  8. Archaeal lipids in oral delivery of therapeutic peptides

    DEFF Research Database (Denmark)

    Jacobsen, Ann-Christin; Jensen, Sara M; Fricker, Gert

    2017-01-01

    Archaea contain membrane lipids that differ from those found in the other domains of life (Eukarya and Bacteria). These lipids consist of isoprenoid chains attached via ether bonds to the glycerol carbons at the sn-2,3 positions. Two types of ether lipids are known, polar diether lipids and bipolar...

  9. Stability of mixing layers

    Science.gov (United States)

    Tam, Christopher; Krothapalli, A

    1993-01-01

    The research program for the first year of this project (see the original research proposal) consists of developing an explicit marching scheme for solving the parabolized stability equations (PSE). Performing mathematical analysis of the computational algorithm including numerical stability analysis and the determination of the proper boundary conditions needed at the boundary of the computation domain are implicit in the task. Before one can solve the parabolized stability equations for high-speed mixing layers, the mean flow must first be found. In the past, instability analysis of high-speed mixing layer has mostly been performed on mean flow profiles calculated by the boundary layer equations. In carrying out this project, it is believed that the boundary layer equations might not give an accurate enough nonparallel, nonlinear mean flow needed for parabolized stability analysis. A more accurate mean flow can, however, be found by solving the parabolized Navier-Stokes equations. The advantage of the parabolized Navier-Stokes equations is that its accuracy is consistent with the PSE method. Furthermore, the method of solution is similar. Hence, the major part of the effort of the work of this year has been devoted to the development of an explicit numerical marching scheme for the solution of the Parabolized Navier-Stokes equation as applied to the high-seed mixing layer problem.

  10. Research progress on polar lipids of deinococcus radiodurans

    International Nuclear Information System (INIS)

    Feng Qiong; Tian Bing; Hua Yuejin

    2013-01-01

    Deinococcus radiodurans is extremely resistant to radiation, desiccation, oxidizing agents and other extreme conditions. One of the unique lipids in Deinococcus radiodurans is the polar lipid phosphoglycolipid with alkylamine as the main component. Alkylamine derived from fatty acids. The composition characteristic of lipids is one of the classification criterias of Deinococcus. This article provided an overview of the main features of the Deinococcus radiodurans and introduced special polar lipids that have been found as well as the taxonomy significances of such lipids. The research progress of the relationship between lipids and their resistance mechanisms and the prospects of special lipids in Deinococcus radidurans have also been discussed. (authors)

  11. Fourier transform infrared imaging showing reduced unsaturated lipid content in the hippocampus of a mouse model of Alzheimer's disease.

    Science.gov (United States)

    Leskovjan, Andreana C; Kretlow, Ariane; Miller, Lisa M

    2010-04-01

    Polyunsaturated fatty acids are essential to brain functions such as membrane fluidity, signal transduction, and cell survival. It is also thought that low levels of unsaturated lipid in the brain may contribute to Alzheimer's disease (AD) risk or severity. However, it is not known how accumulation of unsaturated lipids is affected in different regions of the hippocampus, which is a central target of AD plaque pathology, during aging. In this study, we used Fourier transform infrared imaging (FTIRI) to visualize the unsaturated lipid content in specific regions of the hippocampus in the PSAPP mouse model of AD as a function of plaque formation. Specifically, the unsaturated lipid content was imaged using the olefinic =CH stretching mode at 3012 cm(-1). The axonal, dendritic, and somatic layers of the hippocampus were examined in the mice at 13, 24, 40, and 56 weeks old. Results showed that lipid unsaturation in the axonal layer was significantly increased with normal aging in control (CNT) mice (p avoiding progression of the disease.

  12. Water insoluble and soluble lipids for gene delivery.

    Science.gov (United States)

    Mahato, Ram I

    2005-04-05

    Among various synthetic gene carriers currently in use, liposomes composed of cationic lipids and co-lipids remain the most efficient transfection reagents. Physicochemical properties of lipid/plasmid complexes, such as cationic lipid structure, cationic lipid to co-lipid ratio, charge ratio, particle size and zeta potential have significant influence on gene expression and biodistribution. However, most cationic lipids are toxic and cationic liposomes/plasmid complexes do not disperse well inside the target tissues because of their large particle size. To overcome the problems associated with cationic lipids, we designed water soluble lipopolymers for gene delivery to various cells and tissues. This review provides a critical discussion on how the components of water insoluble and soluble lipids affect their transfection efficiency and biodistribution of lipid/plasmid complexes.

  13. The dynamic of lipid oxidation in human myotubes

    DEFF Research Database (Denmark)

    Gaster, Michael

    2009-01-01

    Both endogenous and exogenous lipid levels may be regulators of total lipid oxidation in skeletal muscles. We studied the dynamics of lipid oxidation in human myotubes established from healthy, lean subjects exposed to acutely and chronically increased palmitate concentrations. The intramyocellular...... triacylglycerol content increased with chronic palmitate exposure. Both, ectopically increased intracellular and extracellular lipid levels were simultaneously oxidized and could partly suppress each other's oxidation. Overall, the highest acute palmitate treatments stimulated fatty acid oxidation whilst...... the highest chronic treatments decreased total lipid oxidation. Intracellular lipids showed a more complete oxidation than exogenous lipids. Endogenous lipids reduced insulin-mediated glucose oxidation. Thus, both endogenous and exogenous lipid concentrations regulated each other's oxidation and total lipid...

  14. Three-layer magnetoconvection

    International Nuclear Information System (INIS)

    Lin, M.-K.; Silvers, L.J.; Proctor, M.R.E.

    2008-01-01

    It is believed that some stars have two or more convection zones in close proximity near to the stellar photosphere. These zones are separated by convectively stable regions that are relatively narrow. Due to the close proximity of these regions it is important to construct mathematical models to understand the transport and mixing of passive and dynamic quantities. One key quantity of interest is a magnetic field, a dynamic vector quantity, that can drastically alter the convectively driven flows, and have an important role in coupling the different layers. In this Letter we present the first investigation into the effect of an imposed magnetic field in such a geometry. We focus our attention on the effect of field strength and show that, while there are some similarities with results for magnetic field evolution in a single layer, new and interesting phenomena are also present in a three layer system

  15. Layered tin dioxide microrods

    International Nuclear Information System (INIS)

    Duan Junhong; Huang Hongbo; Gong Jiangfeng; Zhao Xiaoning; Cheng Guangxu; Yang Shaoguang

    2007-01-01

    Single-crystalline layered SnO 2 microrods were synthesized by a simple tin-water reaction at 900 deg. C. The structural and optical properties of the sample were characterized by x-ray powder diffraction, energy-dispersive x-ray spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, Raman scattering and photoluminescence (PL) spectroscopy. High resolution transmission electron microscopy studies and selected area electron diffraction patterns revealed that the layered SnO 2 microrods are single crystalline and their growth direction is along [1 1 0]. The growth mechanism of the microrods was proposed based on SEM, TEM characterization and thermodynamic analysis. It is deduced that the layered microrods grow by the stacking of SnO 2 sheets with a (1 1 0) surface in a vapour-liquid-solid process. Three emission peaks at 523, 569 and 626 nm were detected in room-temperature PL measurements

  16. Superfluid Boundary Layer.

    Science.gov (United States)

    Stagg, G W; Parker, N G; Barenghi, C F

    2017-03-31

    We model the superfluid flow of liquid helium over the rough surface of a wire (used to experimentally generate turbulence) profiled by atomic force microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that the sharpest features in the surface induce vortex nucleation both intrinsically (due to the raised local fluid velocity) and extrinsically (providing pinning sites to vortex lines aligned with the flow). Vortex interactions and reconnections contribute to form a dense turbulent layer of vortices with a nonclassical average velocity profile which continually sheds small vortex rings into the bulk. We characterize this layer for various imposed flows. As boundary layers conventionally arise from viscous forces, this result opens up new insight into the nature of superflows.

  17. Lxr-driven enterocyte lipid droplet formation delays transport of ingested lipids.

    Science.gov (United States)

    Cruz-Garcia, Lourdes; Schlegel, Amnon

    2014-09-01

    Liver X receptors (Lxrs) are master regulators of cholesterol catabolism, driving the elimination of cholesterol from the periphery to the lumen of the intestine. Development of pharmacological agents to activate Lxrs has been hindered by synthetic Lxr agonists' induction of hepatic lipogenesis and hypertriglyceridemia. Elucidating the function of Lxrs in regulating enterocyte lipid handling might identify novel aspects of lipid metabolism that are pharmacologically amenable. We took a genetic approach centered on the single Lxr gene nr1h3 in zebrafish to study the role of Lxr in enterocyte lipid metabolism. Loss of nr1h3 function causes anticipated gene regulatory changes and cholesterol intolerance, collectively reflecting high evolutionary conservation of zebrafish Lxra function. Intestinal nr1h3 activation delays transport of absorbed neutral lipids, with accumulation of neutral lipids in enterocyte cytoplasmic droplets. This delay in transport of ingested neutral lipids protects animals from hypercholesterolemia and hepatic steatosis induced by a high-fat diet. On a gene regulatory level, Lxra induces expression of acsl3a, which encodes acyl-CoA synthetase long-chain family member 3a, a lipid droplet-anchored protein that directs fatty acyl chains into lipids. Forced overexpression of acls3a in enterocytes delays, in part, the appearance of neutral lipids in the vasculature of zebrafish larvae. Activation of Lxr in the intestine cell-autonomously regulates the rate of delivery of absorbed lipids by inducting a temporary lipid intestinal droplet storage depot. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.

  18. Métodos de extração e qualidade da fração lipídica de matérias-primas de origem vegetal e animal Extraction methods and quality of the lipid fraction of vegetable and animal samples

    Directory of Open Access Journals (Sweden)

    Aelson Aloir Santana Brum

    2009-01-01

    Full Text Available Methodologies of extraction of lipids from chicken breast and oats flakes were evaluated: Soxhlet, Folch et al., Bligh & Dyer and Hara & Radin. For chicken breast, the methods Soxhlet, Folch et al. and Bligh & Dyer presented the highest yields in total lipids. With oat flakes, the methods Soxhlet and Bligh & Dyer presented higher yields than the Hara & Radin and Folch et al. The Soxhlet method affected the quality of the lipid fraction in both samples. Extracted lipid components were separated by thin layer chromatography, the chloroform-methanol based was more efficient to extract the neutral and polar lipids.

  19. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  20. Triglyceride blisters in lipid bilayers: implications for lipid droplet biogenesis and the mobile lipid signal in cancer cell membranes.

    Directory of Open Access Journals (Sweden)

    Himanshu Khandelia

    Full Text Available Triglycerides have a limited solubility, around 3%, in phosphatidylcholine lipid bilayers. Using millisecond-scale course grained molecular dynamics simulations, we show that the model lipid bilayer can accommodate a higher concentration of triolein (TO than earlier anticipated, by sequestering triolein molecules to the bilayer center in the form of a disordered, isotropic, mobile neutral lipid aggregate, at least 17 nm in diameter, which forms spontaneously, and remains stable on at least the microsecond time scale. The results give credence to the hotly debated existence of mobile neutral lipid aggregates of unknown function present in malignant cells, and to the early biogenesis of lipid droplets accommodated between the two leaflets of the endoplasmic reticulum membrane. The TO aggregates give the bilayer a blister-like appearance, and will hinder the formation of multi-lamellar phases in model, and possibly living membranes. The blisters will result in anomalous membrane probe partitioning, which should be accounted for in the interpretation of probe-related measurements.