Validity of a personal and family history of cataract and cataract surgery in genetic studies.

PURPOSE:

To determine the accuracy of a history of cataract and cataract surgery (self-report and for a sibling), and to determine which demographic, cognitive, and medical factors are predictive of an accurate history.

METHODS:

All participants in the Salisbury Eye Evaluation (SEE) project and their locally resident siblings were questioned about a personal and family history of cataract or cataract surgery. Lens grading at the slit lamp, using standardized photographs and a grading system, was performed for both SEE participants (probands) and their siblings. Cognitive testing and a history of systemic comorbidities were also obtained for all probands.

RESULTS:

Sensitivity of a history of cataract provided on behalf of a sibling was 32%, specificity 98%. The performance was better for a history of cataract surgery: sensitivity 90%, specificity 89%. For self-report of cataract, sensitivity was also low at 55%, with specificity at 77%. Self-report of cataract surgery gave a much better performance: sensitivity 94%, specificity 100%. Different cutoffs in the definition of cataract had little impact. Factors predicting a correct history of cataract included high school or greater education in the proband (odds ratio [OR] = 1.13, 95% confidence interval [CI]1.02-1.25) and younger sibling (but not proband) age (OR = 0.94 for each year of age, 95% CI 0.90-0.99). Gender, race and Mini-Mental Status Examination (MMSE) result were not predictive.

CONCLUSIONS:

Whereas accurate self and family histories for cataract surgery may be obtainable, it is difficult to ascertain cataract status accurately from history alone.

Theory and numerical integration of subsurface light transport

En synthèse d’images, reproduire les effets complexes de la lumière sur des matériaux transluminescents, tels que la cire, le marbre ou la peau, contribue grandement au réalisme d’une image. Malheureusement, ce réalisme supplémentaire est couteux en temps de calcul. Les modèles basés sur la théorie de la diffusion visent à réduire ce coût en simulant le comportement physique du transport de la lumière sous surfacique tout en imposant des contraintes de variation sur la lumière incidente et sortante. Une composante importante de ces modèles est leur application à évaluer hiérarchiquement l’intégrale numérique de l’illumination sur la surface d’un objet. Cette thèse révise en premier lieu la littérature actuelle sur la simulation réaliste de la transluminescence, avant d’investiguer plus en profondeur leur application et les extensions des modèles de diffusion en synthèse d’images. Ainsi, nous proposons et évaluons une nouvelle technique d’intégration numérique hiérarchique utilisant une nouvelle analyse fréquentielle de la lumière sortante et incidente pour adapter efficacement le taux d’échantillonnage pendant l’intégration. Nous appliquons cette théorie à plusieurs modèles qui correspondent à l’état de l’art en diffusion, octroyant une amélioration possible à leur efficacité et précision.

Backscattering of Laser Light from Colloidal Silica

Light-scattering experiments gained prominence as potential applications of quantum optics, nonlinear optics, and photon localization. The possibility of the realization of lasing action in random media has created much interest in the study of the coherent structure of the backscattered light from disordered media. Backscattering (BS) studies are carried out to analyze the possibilities of photon localization in colloidal silica. The scattering enhancement is best associated with the density of the scatterers. The width of the BS cone and, hence, the mean-free path is related to the concentration of the medium. The dependence of the photon wavelength on the possible characteristics of the scattering is presented.

Plane wave scattering by a spherical di-electric particle in motion : a relativistic extension of the Mie theory

Light scattering from small spherical particles has applications in a vast number of disciplines including astrophysics, meteorology optics and particle sizing. Mie theory provides an exact analytical characterization of plane wave scattering from spherical dielectric objects. There exist many variants of the Mie theory where fundamental assumptions of the theory has been relaxed to make generalizations. Notable such extensions are generalized Mie theory where plane waves are replaced by optical beams, scattering from lossy particles, scattering from layered particles or shells and scattering of partially coherent (non-classical) light. However, no work has yet been reported in the literature on modifications required to account for scattering when the particle or the source is in motion relative to each other. This is an important problem where many applications can be found in disciplines involving moving particle size characterization. In this paper we propose a novel approach, using special relativity, to address this problem by extending the standard Mie theory for scattering by a particle in motion with a constant speed, which may be very low, moderate or comparable to the speed of light. The proposed technique involves transforming the scattering problem to a reference frame co-moving with the particle, then applying the Mie theory in that frame and transforming the scattered field back to the reference frame of the observer.

Sol-gel synthesis of titania-alumina catalyst supports

Titanium oxide is a good candidate as new support for hydrotreating (HDT) catalysts, but has the inconvenience of presenting small surface area and poor thermal stability. To overcome these handicaps TiO2-Al2O3 mixed oxides were proposed as catalyst support. Here, the results concerning the preparation, characterization and testing of molybdenum catalyst supported on titania-alumina are presented. The support was prepared by sol-gel route using titanium and aluminum isopropoxides, chelated with acetylacetone (acac) to promote similar hydrolysis ratio for both the alcoxides. The effect of nominal complexing ratios [acac]/[Ti] and of sol aging temperature on the structural features of nanometric particles was analyzed by quasi-elastic light scattering (QELS) and N-2 adsorption isotherm measurements. These characterizations have shown that the addition of acac and the increase of aging temperature favor the full dispersion of primary nanoparticles in mother acid solution. The dried powder presents a monomodal distribution of slit-shaped micropores, formed by irregular packing of platelet primary particles, surface area superior to 200 m(2) g(-1) and mean pore size of about 1 nm. These characteristics of porous texture are preserved after firing at 673 K. The diffraction patterns of sample fired above 973 K show only the presence of anatase crystalline phase. The crystalline structure of the support remained unaltered after molybdenum adsorption, but the surface area and the micropore volume were drastically reduced. (C) 2002 Published by Elsevier B.V. B.V.

Fragment and vesicle structures in sonicated dispersions of dioctadecyldimethylammonium bromide

Dynamic light scattering has been used to investigate sonicated aqueous dispersions of dioctadecyldimethylammonium bromide (DODAB). The hydrodynamic radius (R-H) of the scattering particles and the mean scattering intensity (I) have been monitored as functions of the DODAB concentration and temperature (T). In the dilute regime, the relaxation time distribution of the sonicated dispersion of DODAB is bimodal with the slow mode dominating the distribution. The slow and fast modes are respectively characteristic of vesicles and bilayer fragments with R-H values of 22 and 8.5 nm (25 degrees C) and 20 and 6 nm (50 degrees C), respectively. The total scattered intensity initially decreased with temperature up to 45 degrees C (T-c), above which it was constant; identical behavior was observed for the slow mode intensity, but the fast mode intensity was constant with temperature change, showing that T-c is a property of the vesicles and not of the bilayer fragments. At T-c the slow vesicle mode becomes narrower whereas the fast fragment mode shows no change. on aging, the dispersion showed a slow transition from bimodal to a rather broad single-modal relaxation time distribution. The corresponding R-H was 33.8 nm when measured 10 months after preparation. These results suggest that aqueous sonicated dispersions of DODAB are metastable.

Small-angle X-ray scattering study of the smart thermo-optical behavior of zirconyl aqueous colloids

The smart thermo-optical systems studied here are based on the unusual thermoreversible sol-gel transition of zirconyl chloride aqueous solution modified by sulfuric acid in the molar ratio Zr/SO4:3/1. The transparency to the visible light changes during heating due to light scattering. This feature is related to the aggregates growth that occurs during gelation. These reversible changes can be controlled by the amount of chloride ions in solution. The thermoreversible sol-gel transition temperature increases from 323 to 343 K by decreasing the molar ratio Cl/Zr from 7.0 to 1.3. In this work the effect of the concentration of chloride ions on the structural characteristics of the system has been analyzed by in situ SAXS measurements during the sol-gel transition carried out at 323 and 333 K. The experimental SAXS curves of sols exhibit three regions at small, medium and high scattering vectors characteristics of Guinier, fractal and Porod regimes, respectively. The radius of primary particles, obtained from the crossover between the fractal and Porod regimes, remains almost invariable with the chloride concentration, and the value (4 Angstrom) is consistent with the size of the molecular precursor. During the sol-gel transition the aggregates grow with a fractal structure and the fractal dimensionality decreases from 2.4 to 1.8. This last value is characteristic of a cluster-cluster aggregation controlled by a diffusion process. Furthermore, the time exponent of aggregate growth presents values of 0.33 and 1, typical of diffusional and hydrodynamic motions. A crossover between these two regimes is observed.

Desenvolvimento e avaliação das atividades antioxidante e despigmentante in vitro de emulsões múltiplas a/o/a contendo dipalmitato kójico

Currently, there has been a growing concern for men and women with the appearance of the face and body, driven primarily by aesthetic standards set by the media. For this, the pharmaceutical and cosmetic industries have conducted numerous research projects aiming at the development of formulations that mitigate the aging and some skin disorders such as hipercromies. One of the most frequent pathologies of skin is melasma, a manifestation of hyperpigmentation caused by hipermelanogenesis symmetrical and progressive, caused usually by hormonal irregularities, exposure to sunlight and genetic factors. In addition to sunscreen, the treatment is indicated the use of depigmenting substances, among them the kojic dipalmitate (DK), which is cleaved into kojic acid (5- hydroxy-2-hydroxy-methyl-4H-piran-4-one) by esterase after absorption by the skin cells. The kojic acid inhibits the action of tyrosinase as a chelator of ions and promotes the reduction of eumelanin and its precursor monomer. To promote a controlled release and improve the stability of the system, the DK can be incorporated into multiple emulsions, that is, complex systems composed of two emulsifications, where the two types of emulsions (W/O and O/W or O/W and W/O) exist simultaneously, forming emulsions of type W/O/W or O/W/O. This work aimed to incorporate the DK in emulsion W/O/W, physical-chemical systems obtained and to evaluate the antioxidant and depigmenting action in vitro of the developed formulations. The physico-chemical characterization was performed by microscopic analysis, quantification and size distribution, determination of pH, conductivity, zeta potential and bioadhesive test of the formulations. The droplet size in accordance with the use of light microscopy and dynamic light scattering is approximately 1μm. The pH, electrical conductivity and bioadhesion have not changed with the addition... (Complete abstract click electronic access below)

Effects of age condition on the distribution and integrity of inorganic fillers in dental resin composites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Role of Mie scattering in the seeding of matter-wave superradiance

Matter-wave superradiance is based on the interplay between ultracold atoms coherently organized in momentum space and a backscattered wave. Here, we show that this mechanism may be triggered by Mie scattering from the atomic cloud. We show how the laser light populates the modes of the cloud and thus imprints a phase gradient on the excited atomic dipoles. The interference with the atoms in the ground state results in a grating that in turn generates coherent emission, contributing to the backward light wave onset. The atomic recoil "halos" created by the Mie-scattered light exhibit a strong anisotropy, in contrast to single-atom scattering.

Development and applications of hollow fiber flow field-flow fractionation in the bioanalytical field. Studies of aggregation phenomena in complex protein samples

Recent advances in the fast growing area of therapeutic/diagnostic proteins and antibodies - novel and highly specific drugs - as well as the progress in the field of functional proteomics regarding the correlation between the aggregation of damaged proteins and (immuno) senescence or aging-related pathologies, underline the need for adequate analytical methods for the detection, separation, characterization and quantification of protein aggregates, regardless of the their origin or formation mechanism. Hollow fiber flow field-flow fractionation (HF5), the miniaturized version of FlowFFF and integral part of the Eclipse DUALTEC FFF separation system, was the focus of this research; this flow-based separation technique proved to be uniquely suited for the hydrodynamic size-based separation of proteins and protein aggregates in a very broad size and molecular weight (MW) range, often present at trace levels. HF5 has shown to be (a) highly selective in terms of protein diffusion coefficients, (b) versatile in terms of bio-compatible carrier solution choice, (c) able to preserve the biophysical properties/molecular conformation of the proteins/protein aggregates and (d) able to discriminate between different types of protein aggregates. Thanks to the miniaturization advantages and the online coupling with highly sensitive detection techniques (UV/Vis, intrinsic fluorescence and multi-angle light scattering), HF5 had very low detection/quantification limits for protein aggregates. Compared to size-exclusion chromatography (SEC), HF5 demonstrated superior selectivity and potential as orthogonal analytical method in the extended characterization assays, often required by therapeutic protein formulations. In addition, the developed HF5 methods have proven to be rapid, highly selective, sensitive and repeatable. HF5 was ideally suitable as first dimension of separation of aging-related protein aggregates from whole cell lysates (proteome pre-fractionation method) and, by HF5-(UV)-MALS online coupling, important biophysical information on the fractionated proteins and protein aggregates was gathered: size (rms radius and hydrodynamic radius), absolute MW and conformation.

Virtual photon-photon scattering

Based on analyticity, unitarity, and Lorentz invariance the contribution from hadronic vacuum polarization to the anomalous magnetic moment of the muon is directly related to the cross section of e+e− → hadrons. We review the main difficulties that impede such an approach for light-by-light scattering and identify the required ingredients from experiment. Amongst those, the most critical one is the scattering of two virtual photons into meson pairs. We analyze the analytic structure of the process γ*γ* → ππ and show that the usual Muskhelishvili–Omnès representation can be amended in such a way as to remain valid even in the presence of anomalous thresholds.

Quantitative scattering of melanin solutions

The optical scattering coefficient of a dilute, well-solubilized eumelanin solution has been accurately measured as a function of incident wavelength, and found to contribute < 6% of the total optical attenuation between 210 and 325 nm. At longer wavelengths (325-800 nm), the scattering was less than the minimum sensitivity of our instrument. This indicates that ultraviolet and visible optical density spectra can be interpreted as true absorption with a high degree of confidence. The scattering coefficient versus wavelength was found to be consistent with Rayleigh theory for a particle radius of 38 6 1 nm. Our results shed important light on the role of melanins as photoprotectants.

Polymer-phospholipid complexes for the solubilisation and delivery of drugs to the eye

Aim: Topical application of ophthalmic drugs is very inefficient; contact lenses used as drug delivery devices could minimize the drug loss and side effects. Styrene-maleic acid copolymers (PSMA) can form polymer-phospholipid complexes with dipalmitoyl phosphatidylcholine (DMPC) in the form of nanometric vesicles, which can easily solubilise hydrophobic drugs. They can be dispersed on very thin contact lens coatings to immobilize the drug on their surface. Methods: Two types of complexes stable at different pH values (5 and 7 respectively) where synthesized and loaded with drugs of different hydrophilicities during their formation process. The drug release was studied in vitro and compared to the free drug. Results: The mean sizes of the complexes obtained by light scattering were 50 nm and 450 nm respectively with low polydispersities. However, they were affected by the drugs load and release. An increase was observed in the duration of the release in the case of hydrophobic drugs, from days to weeks, avoiding initial “burst” and with a lesser amount of total drug released due to the interaction of the drug with the phospholipid core. The size and charge of the different drugs and the complexes nature also affected the release profile. Conclusions: Polymer-phospholipid complexes in the form of nanoparticles can be used to solubilise and release hydrophobic drugs in a controlled way. The drug load and release can be optimised to reach therapeutic values in the eye.

New strategy to overcome the intrinsic difficulty of phospholipids solubilisation and delivery to the eye

Purpose: Lipids play a vital role at interfaces such as the tear film in the protection of the anterior eye. Their role is to act as lubricants and reduce surface and interfacial tension. Although there is a lack of appropriate methods to solubilize and dilute phospholipids to the tear film. Here, we report that styrene-maleic acid copolymers (PSMA), can form polymer–lipid complexes in the form of monodisperse nanometric particles, which can easily solubilise these phospholipid molecules by avoiding for example, the use of any kind of surfactant. Method: The interactions of PSMA with phospholipids have been studied by its adsorption from aqueous solutions into monolayers of dimyristoyl-phosphorylcholine (DMPC). The Langmuir trough (LT) technique is used to study this pH-dependant complex formation. The formed nanoparticles have been also analysed by 31P NMR, particle size distribution by light scattering (DLS) and morphology by electron microscopy (SEM). Results: The LT has been found to be a useful technique for in vitro simulation of in vivo lipid layer behaviour: The limiting surface pressure of unstable tear films ranges between 20 and 30 mN/m. More stable tear films show an increase in surface pressure, within the range of 35–45 mN/m. The DMPC monolayers have a limiting surface pressure of 38 mN/m (water), and 45 mN/m (pH 4 buffer), and the PSMA-DMPC complexes formed at pH 4 have a value of 42 mN/m, which resembles that of the stable tear film. The average particle size distribution is 53 ± 10 nm with a low polydispersity index (PDI) of 0.24 ± 0.03. Conclusions: New biocompatible and cheap lipid solubilising agents such as PSMA can be used for the study of the tear film composition and properties. These polymer–lipid complexes in the form of nanoparticles can be used to solubilise and release in a controlled way other hydrophobic molecules such as some drugs or proteins.