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La queratoconjuntivitis por Microsporidiumes un cuadro infrecuente. Se ha asociado a brotes epidémicos en Asia relacionados con la exposición a agua o tierra contaminada. Habitualmente estos cuadros son autolimitados y leves, pero pueden tener evoluciones prolongadas. Presentamos el caso de una paciente de 29 años que comenzó con dolor, enrojecimiento, visión borrosa en su ojo derecho tras su vuelta de un viaje a Singapur y que no mejoró tras un tratamiento convencional frente a conjuntivitis. Fue diagnosticada de queratoconjuntivitis por Microsporidiummediante PCR y tinción con PAS del epitelio corneal. El tratamiento inicial fue desbridamiento epitelial, albendazol oral y voriconazol, levofloxacino y propamidina, pero la enfermedad conjuntival y corneal no cedió hasta que si introdujeron corticoides tópicos 5 meses después para tratar la limbitis.

Minimizar la exposición al virus SARS-CoV-2, reducir las posibilidades de transmisión cruzada entre pacientes y personal sanitario, y evitar el desarrollo de complicaciones postoperatorias por la atención a pacientes con enfermedades oculares durante la pandemia de enfermedad por coronavirus 2019 (COVID-19).

In the polar regions, ocean wave propagation is affected by the presence of sea ice. In particular, the waves are observed to attenuate exponentially due to scattering and dissipative effects. Here we derive a transport equation and the associated attenuation coefficient for linear ocean wave packets in one horizontal dimension due to scattering only, assuming that the ocean is covered with ice of spatially varying thickness. This thickness variation is assumed to occur at length scales that are comparable to the wavelength but short compared to the observation scale over which the attenuation is measured. We use a multiple scale expansion and a Wigner transform to arrive at the transport equation. We find that the resulting attenuation coefficient generally overestimates the attenuation that we expect to see in a real ice-covered ocean. We argue that this is likely to be due to the one-dimensional nature of our model. • Derivation of a transport equation for 1D waves under ice. • Derivation of attenuation coefficient in terms of statistical ice cover properties. • Resulting attenuation coefficient appears to overestimate actual attenuation rates. [ABSTRACT FROM AUTHOR]

La queratopatía neurotrófica (QN) es una enfermedad corneal degenerativa causada por un daño en la inervación del nervio trigémino. Esta situación produce defectos epiteliales, ulceración y, eventualmente, perforación. Tanto la queratitis por herpes simple como por varicela zoster constituyen la principal causa de QN. Además, el pronóstico en este tipo de QN es pobre. Los hallazgos clínicos clásicos en la QN postherpética incluyen la rotura epitelial espontánea, defectos epiteliales ovalados y centrales de bordes suaves, queratolisis con adelgazamiento del estroma, cicatrización y neovascularización. Aunque se han descrito tratamientos médicos y quirúrgicos prometedores, actualmente no hay un tratamiento definitivo para restaurar la sensibilidad de la córnea. Por tanto, la QN sigue siendo un reto terapéutico. En esta revisión resumimos la patogenia, la clínica y el tratamiento actual de la QN postherpética. Se discute el papel del tratamiento antiviral y de las vacunas contra el virus de la varicela-zoster. Se describen nuevas terapias médicas y quirúrgicas, como los agentes regenerativos y la neurotización corneal.

This paper investigates the attenuation and directional spreading of large amplitude waves traveling through pancake ice. Directional spectral density is analyzed from in situ wave buoy data collected during a 3‐day storm event in October 2015 in the Beaufort Sea. Two proxy metrics for wave amplitude obtained from energy density spectra, namely, spectral amplitude and significant wave height, are used to track the waves as they propagate along transects through the array of buoys in the predominantly pancake ice field. Two types of wave buoys are used in the analysis and compared, exhibiting significant differences in the wave energy density and directionality estimates. Although exponential decay is observed predominantly, one of the two buoy types indicates a potential positive correlation between wave energy density and the occurrence of linear wave decay, as opposed to exponential decay, in accord with recent observations in the Antarctic marginal ice zone. Factors affecting the validity of this observation are discussed. An empirical power law with exponent 2.2 is also found to hold between the exponential attenuation coefficient and wave frequency. The directional content of the wave spectrum appears to decrease consistently along the wave transects, confirming that wave energy is being dissipated by the pancake ice as opposed to being scattered by ice cakes. Ocean waves in the Arctic Ocean are becoming increasingly energetic as a result of the retreating sea ice caused by climate change. Very little is known of the physical processes governing the interactions between ocean waves in sea ice, however, mainly due to the lack of field data measuring the underlying physics. Here we analyze a data set acquired by a collection of wave measuring devices in the Beaufort Sea over a 3‐day period in October 2015, as part of a large experimental program funded by the the U.S. Office of Naval Research. This period coincided with a storm event with waves up to 5 m high. We analyzed the attenuation of such large waves as well as smaller amplitude waves due to the sea ice cover, which mainly consisted of pancake ice. We found that large waves as well as long waves attenuate much more slowly than small waves and short waves. In particular, the more energetic the waves the more likely they are to decay linearly, as opposed to exponentially, with distance, which is in agreement with a similar observation made in the Southern Ocean in 2012. Possible processes causing this effect are discussed in the paper. In situ data of a large wave event propagating through pancake ice are analyzed for attenuation and directional spreadingWave decay through O(10 km)‐long transects is predominantly exponential with attenuation rate related to frequency according to a power lawObserved directional narrowing of the wave spectrum is caused by wave dissipation from pancake ice

We consider the scattering of water waves in a two dimensional domain from a floating sea ice floe of random length. The length is treated as a random variable governed by a prescribed probability distribution. To keep the focus on the random length aspect we choose a simple mass loading model to characterise the ice floe. We compute the expectation and variance of the reflection and transmission coefficients using two different methods derived from the framework of generalised polynomial chaos (gPC), as part of which unknown quantities of the problem are expanded in a basis of orthogonal polynomials of the random variable. The polynomials are chosen optimally for the particular probability distribution of the random variable to minimise an approximation error. We devise a stochastic collocation method, which involves computing the reflection and transmission coefficients deterministically for a number of carefully sampled lengths and fitting polynomial expansions to them. The second approach is based on the stochastic Galerkin method, for which the governing equations are transformed to accommodate the random length parameter. We also use a standard Monte Carlo (MC) approach for comparison. The gPC methods are shown to be numerically efficient and exhibit desirable exponential convergence properties, as opposed to the slow inverse square root convergence of the MC approach. Finally, we use the statistic collocation method to demonstrate that the floe size distribution can have a significant impact on the expected transmission coefficient. [ABSTRACT FROM AUTHOR]

Sonic crystals are scatterers arranged periodically in a homogeneous fluid medium, for which sound does not transmit through the crystal in certain frequency bands known as stop bands. Acoustic wave transmission through a two-dimensional sonic crystal composed of a finite array of scatterers is investigated. Two types of scatterers are considered: sound-hard cylinders and C-shaped locally resonant scatterers. An analytical method is devised to solve the corresponding multiple scattering problems. The method combines an integral equation technique for the single scatterer with an enhanced multipole method using domain decomposition into slabs. A numerical approach using commercial software is also considered for validation and is based on the finite element method. Simulations of sound transmission through an array of 5 by 51 scatterers show remarkably good agreement with the corresponding infinite system. For an array comprising locally resonant scatterers, an approximate band gap around the resonator natural frequency is observed in addition to the band gap due to the overall periodicity of the finite sonic crystal. [ABSTRACT FROM AUTHOR]

Mujer de 81 años y varón de 63, que desarrollan un hematoma pre-descemético (HPD) tras una esclerectomía profunda no perforante (EPNP), la primera durante la cirugía y el segundo durante el postoperatorio precoz. Se describe la técnica quirúrgica que permite tanto la evacuación del hematoma como la preservación de la integridad de la membrana trabéculo-descemética. Se presentan los hallazgos de OCT de segmento anterior tras la cirugía.

Se describe un método simplificado para detectar lenticono anterior. Realizamos imágenes Scheimpflug del segmento anterior con Pentacam a 3 ojos de 2 pacientes con lenticono anterior y 16 ojos de controles sanos. Se identificó el ángulo del ápex de la cápsula anterior y se midió con AutoCAD.

The analysis of gratings of arbitrary depth, profile, and permittivity is conducted by cutting the modulated region into different slices for which the differential theory of gratings is able to compute the diffracted field for both TE and TM polarization without numerical instabilities. The use of a suitable transition matrix (R matrix) then allows one to analyze the entire stack without encountering the numerical instabilities that generally occur with use of the T-transmission matrix, which is well known in stratified media theory. The use of the R-matrix propagation algorithm provides a breakthrough for grating theoreticians in the sense that it not only permits the study of grating of arbitrary depth but also eliminates the numerical instabilities that have plagued the differential theory in TM polarization during the past 20 years.

An electromagnetic analysis of diffraction by Fresnel linear zone plates ruled into a homogeneous or a stratified media is developed. It takes advantage of the new possibilities brought by the introduction of the R-matrix propagation algorithm into the theory of lamellar gratings, namely, the large increase of the stability domain of the numerical results. Thus a linear Fresnel zone plate can be delt with as a period of such a grating, and the diffracted field can be computed for both TE and TM polarizations. Numerical examples show the convergence of the method and study the focusing properties of positive and negative zone plates. The influence of different parameters such as incidence or number of lines is pointed out.

We develop a rigorous electromagnetic analysis to study the field diffracted by a metallic or dielectric grating made of rectangular rods, lying over a stratified media. The analysis generalizes the modal theory of perfectly conducting lamellar gratings combined with the R-matrix propagation algorithm in order to avoid numerical instabilities, thus allowing treatment of layers and gratings of arbitrary thickness. We then study the field map obtained under the conditions stated in a previous patent that described a process for casting on a support the faithful reproduction of a mask pierced with periodically distributed slits. We make a systematic study of the influence of the various parameters (incidence, mark–space ratio, groove spacing, groove depth, polarization, conductivity of the metal) on the field map below the mask. We discover a large tolerance over the parameters, close to the values stated in the patent. The result is that the setup described in the patent valid for periodic maps can be used for duplicating nonperiodic masks (e.g., linear Fresnel zone plates) as well as chirped gratings or gratings with nonrectilinear grooves.

High-blaze-angle multilayer coated echelette gratings used in very high (i.e., from 10th to 60th) orders and operating with not too small (≈ 5°) glancing angles of incidence turn out to be necessary for achieving ultrahigh resolution and collecting important flux in x-ray fluorescence spectroscopy. Predicting their diffracting behavior appears to be a challenge to grating theoreticians, because such gratings are associated with the three main difficulties encountered in grating-efficiency numerical computation, namely, low wavelength-to-groove-spacing ratio, large modulation, and multiple interpenetrating profiles. We propose a method to resolve the problem that combines the differential theory of gratings, the R-matrix propagation algorithm, and an asymmetric truncation of the Fourier series of the field. The numerical results are checked against many criteria. For a particular mounting they are compared with those given by a phenomenological formula that was developed for bare echelette gratings and turns out still to apply for multilayer-coated gratings. The theory is developed not only for periodic stacks but also for stacks made of layers with varying thicknesses, such as those used in supermirrors.

Abstract: Scanning isoelectric focusing has been employed for continuous monitoring of the isoelectric spectrum of highly purified cholera enterotoxin in 4% polyacrylamide gels containing 2% ampholytes pH 3–10. The resolution obtained by this technique is of high order because at no instance during focusing interruption of current occurs and thus diffusion of the isolated protein moieties is suppressed. An added aspect of scanning isoelectric focusing was that it allowed estimation of the minimal focusing time of cholera enterotoxin. Thus under the standard assay procedure, the main basic component of cholera enterotoxin was focused in 5800 sec, while the other at least 3 minor acidic and anodic components were focused in approximately 19000 sec. Focusing of cholera enterotoxin in the presence of 6m urea allowed the visualization of 5 well defined and about equal components. The proteinaceous nature of the observed peaks was verified by scanning at wavelengths other than 280 nm, staining of gels for protein, and varying the concentration of the enterotoxin. The design of scanning isoelectric focusing equipment is presented. Reproducibility, economy of sample, and ampholytes and simplicity of experimental technique were some of the features of this apparatus. The resolution of scanning isoelectric focusing was found to be superior to that of ordinary disc and SDS gel electrophoresis.

A polymerase chain reaction able to amplify Mycobacterium tuberculosis DNA from clinical samples of extra-pulmonary origin is described. The PCR amplified a 294 base pair DNA fragment spanning positions 5'-782 to 3'-1075 of the 65 kDa M. tuberculosis antigen gene. The procedure enables amplification of target DNA at quantities as low as 1 pg of purified material and less than 1000 mycobacteria present in clinical samples. The reaction amplifies M. tuberculosis DNA as well as Mycobacterium bovis BCG DNA. In 34 extra-pulmonary clinical samples studied, 18 rendered positive results and two false-negative results; compared to classical diagnostic procedures, the sensitivity was 90% and specificity 100%. The PCR approach to diagnosis of tuberculosis of extra-pulmonary origin is a valid diagnostic alternative to classical procedures Copyright 1993, 1999 Academic Press

We have studied the effect of butyrate and other short-chain fatty acids on thyroid hormone nuclear receptors in C6 cells, a rat glioma cell line. Exposure of C6 cells to butyrate leads to increased levels of L-triiodothyronine (T3) in the nuclear and extranuclear compartments. The rise in nuclear binding is not merely a reflection of the higher cellular hormone content, and Scatchard analysis of T3 binding to isolated nuclei reveals that butyrate increases receptor number without changing affinity. The effect on the receptor is quantitatively important: a 48-h incubation with 2 mM butyrate increases nuclear binding by 2-3-fold, and 5 mM butyrate by 3-5-fold. Other short-chain fatty acids were found to similarly influence both nuclear receptor and extranuclear T3 levels with the following potency: butyrate greater than valerate greater than propionate greater than acetate. On the contrary, ketone bodies were ineffective. Butyrate increases receptor levels by decreasing receptor degradation, since the apparent t1/2 of receptor disappearance increased by approximately 3-fold in cells incubated with 2 mM butyrate for 48 h. The regulation of receptor number might be secondary to an action of butyrate on regions of the chromatin to which the receptor associates. We then examined the effect of butyrate on histone acetylation. The fatty acid had little effect in increasing the level of multiacetylated forms of H3 and H4 histone when studied in acid-urea gels, but it markedly inhibited the turnover of [3H] acetate from the histone fraction. There was a striking similarity in the dose-response of butyrate for increasing receptor levels and inhibiting histone deacetylation. Furthermore, a very close correlation between receptor levels and [3H]acetate release was also found when different short-chain fatty acids were used. We thus conclude that the effect of butyrate on the receptor could be explained by a modification of the chromatin structure of C6 cells secondary to acetylation.

The presence of insulin receptor and its regulation by butyrate and other short-chain fatty acids was studied in C6 cells, a rat glioma cell line. Intact C6 cells bind 125I-insulin in a rapid, reversible and specific manner. Scatchard analysis of the binding data gives typical curvilinear plots with apparent affinities of approx. 6 nM and 70 nM for the low-affinity (approx. 90% of total) and high-affinity (approx. 10% of total) sites respectively. Incubation with butyrate results in a time- and dose-dependent decrease of insulin binding to C6 cells. A maximal effect was found with 2 mM-butyrate that decreased the receptor by 40-70% after 48 h. Butyrate decreased numbers of receptors of both classes, but did not significantly alter receptor affinity. Other short-chain fatty acids, as well as keto acids, had a similar effect, but with a lower potency. Cycloheximide caused an accumulation of insulin receptors at the cell surface, since insulin binding increased and receptor affinity did not change after incubation with the inhibitor. Simultaneous addition of butyrate and cycloheximide abolished the loss of receptors produced by the fatty acid. In cells preincubated with butyrate, cycloheximide also produced a large increase in receptor numbers, showing that in the absence of new receptor synthesis a large pool of receptors re-appears at the surface of butyrate-treated cells.