Impact of environmental pollution on the ocular surface of Sjögren's syndrome patients / Impacto da poluição ambiental na superfície ocular de pacientes com síndrome de Sjögren

ABSTRACT Purpose: To evaluate the effect of air pollution on the ocular surface of patients with Sjögren's syndrome. Methods: We investigated the ocular surfaces of thirty patients with Sjögren's syndrome and thirty healthy volunteers (control group) living in the Metropolitan Area of Buenos Aires. We used nitrogen dioxide as an indicator of exposure to air pollution. An ocular symptoms questionnaire was answered by all subjects, who also underwent a complete ocular surface ophthalmic examination-including an Ocular Surface Disease Index questionnaire, biomicroscopy, tear breakup time, Schirmer 1 test, corneal and conjunctival vital staining with fluorescein and lissamine green, tear lysozyme concentration, and impression cytology. Results: In almost all ocular surface test findings, we found a positive and significant correlation between higher levels of exposure to air pollution and higher levels of ocular surface damage in both the control group and Sjögren's syndrome patients. In Sjögren's syndrome patients, the Ocular Surface Disease Index questionnaire, tear breakup time, vital staining and impression cytology showed a significant correlation between high levels of air pollution and ocular surface disease. In the control group, the Ocular Surface Disease Index questionnaire, tear breakup time, and impression cytology showed a significant correlation between high levels of air pollution and ocular surface disease. Conclusions: Here we demonstrated that in patients with dry eye syndrome associated with Sjögren, abnormalities of the ocular surface and eye irritation related to air pollution are more severe than those in the control group. We believe that measuring air quality should be not only an integral part of the evaluation of ocular surface disease but also a therapeutic consideration.

RESUMO Objetivo: Avaliar o efeito da poluição do ar na superfície ocular de pacientes com síndrome de Sjögren. Métodos: Foram investigadas as superfícies oculares de trinta pacientes com síndrome de Sjögren e trinta voluntários saudáveis (grupo controle) residentes na Região Metropolitana de Buenos Aires. Usamos o dióxido de nitrogênio como um indicador de exposição à poluição do ar. Um questionário de sintomas oculares foi respondido por todos os indivíduos, que também foram submetidos a um exame oftalmológico completo da superfície ocular - incluindo um questionário do Índice da Doença da Superfície Ocular, biomicroscopia, tempo de ruptura do filme lacrimal, teste de Schirmer 1, coloração da córnea e conjuntiva com fluoresceína e lissamina verde, concentração de lisozima lacrimal e citologia de impressão. Resultados: Em quase todos os achados do teste de superfície ocular, encontramos uma correlação positiva e significativa entre níveis mais altos de exposição à poluição do ar e níveis mais elevados de danos na superfície ocular tanto no grupo controle quanto nos pacientes com síndrome de Sjögren. Em pacientes com síndrome de Sjögren, o questionário do Índice da Doença da Superfície Ocular, tempo de ruptura do filme lacrimal, coloração vital e citologia de impressão mostraram uma correlação significativa entre altos níveis de poluição do ar e doença da superfície ocular. No grupo controle, o questionário do Índice de Doenças da Superfície Ocular, tempo de ruptura do filme lacrimal e citologia de impressão mostraram uma correlação significativa entre altos níveis de poluição do ar e doença da superfície ocular. Conclusões: Aqui demonstramos que, pacientes com síndrome de olho seco associada a Sjögren, as anormalidades da superfície ocular e a irritação ocular relacionadas à poluição do ar são mais graves do que aquelas no grupo controle. Acreditamos que a medição da qualidade do ar não deve ser apenas uma parte integral da avaliação da doença da superfície ocular, mas também uma consideração terapêutica.

SAD phasing with in-house Cu Kα radiation using barium as anomalous scatterer.

Phasing of lysozyme crystals using co-crystallized barium ions was performed using single-wavelength anomalous diffraction (SAD) method using Cu Kα radiation with in-house source of data collection. As the ion binding sites vary with respect to the pH of the buffer during crystallization, the highly isomorphic forms of lysozyme crystals grown at acidic and alkaline pH were used for the study. Intrinsic sulphur anomalous signal was also utilized with anomalous signal from lower occupancy ions for phasing. The study showed that to solve the structure by SAD technique, 2.8-fold data redundancy was sufficient when barium was used as an anomalous marker in the in-house copper X-ray radiation source for data collection. Therefore, co-crystallization of proteins with barium containing salt can be a powerful tool for structure determination using lab source.

Polaron hopping in some biomolecular solids and their charge transfer complexes.

The solid state spectroscopy of charge transfer complexes of biomolecules such as fatty acids, tripalmitin, lysozyme. folic acid, beta-carotene, cytochrome c, valinomycin and gramicidin has been carried out. The absorption coefficient is related with electronic conductivity. A half-power beta density is found common among these macromolecular solids, indicating photon-induced polaron hopping or hopping of a charge carrier between two branches of a polariton. Band gap vs full width at half-maximum of the mid-IR peak also reveals a linear relation.

Identification and characterization of a new putative c-type lysozyme from malaria vector Anopheles stephensi.

Lysozyme (E.C. 3.2.1.17) activity is reported from the malaria vector Anopheles stephensi. The activity was detected in the salivary gland and midgut using bacteriolytic radial diffusion assay. Spectrophotometric analysis indicated that higher level of lysozyme activity was maintained in both midgut and salivary gland tissues. The activity reached the highest level in 4-8 days old mosquitoes. Genomic PCR amplification revealed the presence of at least two putative lysozyme genes in the mosquito genome. Preliminary analysis of one of the 413 bp genomic fragments showed 56% identity to the lysozyme of mosquito A. gambiae. However, the nature and origin of the putative cloned lysozyme gene remains elusive.

Pressure-assisted cold denaturation of hen egg white lysozyme: the influence of co-solvents probed by hydrogen exchange nuclear magnetic resonance

COSY proton nuclear magnetic resonance was used to measure the exchange rates of amide protons of hen egg white lysozyme (HEWL) in the pressure-assisted cold-denatured state and in the heat-denatured state. After dissolving lysozyme in deuterium oxide buffer, labile protons exchange for deuterons in such a way that exposed protons are substituted rapidly, whereas "protected" protons within structured parts of the protein are substituted slowly. The exchange rates k obs were determined for HEWL under heat treatment (80°C) and under high pressure conditions at low temperature (3.75 kbar, -13°C). Moreover, the influence of co-solvents (sorbitol, urea) on the exchange rate was examined under pressure-assisted cold denaturation conditions, and the corresponding protection factors, P, were determined. The exchange kinetics upon heat treatment was found to be a two-step process with initial slow exchange followed by a fast one, showing residual protection in the slow-exchange state and P-factors in the random-coil-like range for the final temperature-denatured state. Addition of sorbitol (500 mM) led to an increase of P-factors for the pressure-assisted cold denatured state, but not for the heat-denatured state. The presence of 2 M urea resulted in a drastic decrease of the P-factors of the pressure-assisted cold denatured state. For both types of co-solvents, the effect they exert appears to be cooperative, i.e., no particular regions within the protein can be identified with significantly diverse changes of P-factors.

Conformational features of reduced and disulfide intact forms of hen egg white lysozyme in aqueous solution in presence of 3-chloro-1, 2-propanediol and dioxane: implications for protein folding intermediates.

Conformational features of reduced and disulfide intact hen egg white lysozyme in aqueous 1,4-dioxane and 3-chloro-1, 2-propanediol solutions have been examined using circular dichroism and fluorescence spectroscopy. We find that in presence of 1, 4-dioxane, reduced lysozyme assumes a relatively compact conformational form with secondary structure closer to native state and no tertiary structure as judged by peptide and aromatic CD spectra and ANS binding studies monitored by fluorescence. Further, in presence of 40% (v/v) 3-chloro-1, 2-propanediol, disulfide intact lysozyme (DI-lysozyme) assumes a conformational form with native like secondary structure and no tertiary structure akin to a molten globule state. We correlate our results to kinetic hydrogen- deuterium exchange NMR results of the refolding of lysozyme available in literature and suggest that the conformational forms observed in our study could be models for kinetic intermediates in the refolding of lysozyme.

Effect of denaturants and stabilisers on protein adsorption at solid-liquid interfaces.

The adsorption isotherms of different proteins from aqueous solution to the surface of different solids have been compared in the presence of additives such as urea, surfactants and high concentration of various neutral salts. The adsorption isotherms of lysozyme on alumina are not affected much in the presence of 8 M urea showing the rigid structure of lysozyme whereas isotherms of hemoglobin show surface coagulation even in presence of 2 M urea. In presence of 8 M urea, adsorption isotherms of BSA on alumina show two distinct steps. The extent of protein adsorption in the presence of surfactants depends on the nature of surfactants as well as of the underlying surface. The adsorption isotherms of BSA and lysozyme in presence of 2 M concentration of different neutral salts have also been compared with each other. In the presence of denaturants such as NaI and LiCl, the proteins are adsorbed in unfolded beta-conformation whereas in the presence of protein stabilizers such as NaCl, KCl and Na2SO4, amount of protein adsorbed at saturation is zero or extremely small showing that unfolding of proteins at the interface is necessary for initial stage of protein adsorption. The standard free energy change (delta G degrees) per square meter of the surface, signifying relative affinity of adsorption at the state of monolayer saturation, have been calculated. The magnitude of standard free energy of transfer (delta G degrees B) of one mole of protein to the surface in presence of all the additives was found close to 40 kJ/mole.

Positron annihilation studies in lysozyme and catalase.

Positron annihilation studies have been carried out in two enzymes, lysozyme and catalase. Temperature dependence of the positron lifetimes in these two enzymes has been investigated. The results explained in terms of the free volume model and fluctuations between different conformational microstates of enzyme structures provide a new insight into the mechanism of bio-activity of these enzymes.

Electrostatic interactions of charged ionizable groups with the single histidine residue in lysozyme

Foram calculadas as interaçöes eletrostáticas de grupos ionizáveis carregados positiva e negativamente com o resíduo único de histidina, em lisozima de clara de ovo, por meio de um modelo dielétrico uniforme. Na medida em que os átomos envolvidos säo expostos a um solvente ou se localizam próximo à superfície da proteína, foram consideradas somente as interaçöes mediadas pelo solvente (E=80). Foi calculada também a energia total de interaçäo G=1,84 Kcal.mol-1, equivalendo a pK=-1,34. Admitindo-se um pK=7,0 näo pertubado (intrínseco) para o resíduo de histidina, obtém-se um pK aparente de 5,7, valor de acordo com o de 5,8 encontrado na literatura. Esse procedimento simplificado é aplicável a outras proteínas que possuem grupos ionizáveis carregados expostos a solventes, com o intuito de calcular as interaçöes eletrostáticas e determinar sua influência na ionizaçäo de resíduos de aminoácidos nessas proteínas