The rheological behavior of PBT/LLDPE and PBT/LLDPE‐g‐AA blends [where PBT is poly(butylene terephthalate), LLDPE is linear low‐density polyethylene, and AA is acrylic acid] under a capillary flow was investigated with a capillary rheometer. The Utracki equation was used to describe the viscosity–composition dependence of PBT/LLDPE and PBT/LLDPE‐g‐AA blends at low shear stresses. However, at high shear stresses, this equation was not suitable for these blending systems. There existed a maximum on the curves of the entrance pressure drop versus the blending compositions, and the interlayer slip factor β in the Utracki equation was related not only to the shear stress but also to the elasticity difference of the two blending components. Morphological observations indicated that at high shear rates, there existed two different morphologies at different positions of the extrudates, and this was the reason that the Utracki equation failed. Near the wall of the capillary, low‐viscosity PBT stratified, and this resulted in an additional decrease in the viscosities of the blending systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 206–213, 2003

BackgroundOcular mucosa is exposed constantly to the external environment, and chronic exposure to air pollution may affect the ocular surface.ObjectiveWe assessed the effect of air pollution on the ocular surface by combining determinations of individual exposure and conjunctival impression cytology.MethodsA panel study was conducted with 29 volunteers recruited in two locations with different pollution levels: São Paulo (n = 13) and Divinolândia (n = 16). We assessed mean individual levels of nitrogen dioxide (NO2) exposure for 7 days, using a passive sampler. Impression cytology samples were obtained from inferior tarsal conjunctiva. Comparisons between the two groups in terms of NO2 exposure and goblet-cell counts were performed using the Student t-test. Correlations between goblet-cells counts and corresponding individual NO2 exposure levels were determined using Spearman’s correlation.ResultsIndividuals living in São Paulo received a significantly (p = 0.005) higher dose of NO2 (mean 32.47; SD 9.83) than those living in Divinolândia (mean 19.33; SD 5.24). There was a steady increase in goblet-cell counts, proportional to NO2 exposure (Spearman’s correlation = 0.566, p = 0.001), with a dose–response pattern.ConclusionsA positive and significant association between exposure to air pollution and goblet-cell hyperplasia in human conjunctiva was detected. The combination of simple measurements of exposure and impression cytology was an effective and noninvasive approach for characterizing human response to ambient levels of air pollution.

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Exposure to air pollution reduces tear film stability and influences tear film osmolarity. Combining clinical examination with the assessment of tear osmolarity may help understand ocular surface response to high levels of air pollution.

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Citation: Tau J, Novaes P, Matsuda M, Tasat DR, Saldiva PH, Berra A. Diesel exhaust particles selectively induce both proinflammatory cytokines and mucin production in cornea and conjunctiva human cell lines. Invest Ophthalmol Vis Sci. 2013;54:4759-4765. DOI:10.1167/iovs.12-10541 PURPOSE. To evaluate the effect of diesel exhaust particles (DEP) on the viability, proliferation, apoptosis, secretion of cytokines (IL-6, IL-8, and TNF-a), and mucin gene transcription (MUC1, MUC5AC, and MUC16) in human epithelial cells of the cornea (HCLE) and conjunctiva (IOBA-NHC).METHODS. HCLE and IOBA-NHC cells were incubated with DEP (10-500 lg/mL) for 24 hours. Cell proliferation was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptotic cells were measured by an annexin V-FITC and propidium iodide kit for flow cytometry. Proinflammatory cytokines were determined by an ELISA kit. Mucin gene transcription was quantified by real-time PCR.RESULTS. DEP significantly decreased the viability, proliferation, and secretion of IL-8, but increased the secretion of IL-6 on both HCLE and IOBA-NHC cell lines in a dose-dependent manner. Neither cornea nor conjunctiva cells incubated with DEP released TNF-a. DEP induced a significant increase in the percentage of apoptotic cells in IOBA-NHC, whereas no changes were observed in HCLE. Finally, DEP significantly decreased the transcription levels of MUC1 and MUC16 in HCLE, but increased the transcription levels of MUC1, MUC5AC, and MUC16 in IOBA-NHC.CONCLUSIONS. These findings suggest that human corneal and conjunctival epithelial cells incubated with DEP showed cytotoxicity and an inflammatory response mediated by IL-6, not by TNF-a or IL-8. Also, the decrease in mucin expression in the cornea cells might leave exposed areas in the cornea for contact with DEP. Finally, the increase in mucin expression in the conjunctiva cells might be involved at least in the clearance of DEP to protect the ocular epithelium.Keywords: diesel, corneal epithelium, conjunctiva OBJETIVO. Evaluar el efecto de las partículas de Diesel (DEP, del Inglés Diesel Exhaust Particles) sobre la viabilidad, la proliferación, la apoptosis, la secreción de citoquinas (IL-6, IL-8 y TNF-a) y la transcripción de genes de mucinas (MUC1, MUC5AC y MUC16) en células epiteliales humanas de córnea (HCLE) y conjuntiva (IOBA-NHC).MÉTODOS. La viabilidad celular se evaluó por el ensayo de exclusión con azul de tripán. La proliferación celular se evaluó por el ensayo de 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT). La cantidad de células apoptóticas se midió por citometría de flujo. La determinación de citoquinas pro-inflamatorias se realizó por ELISA. La transcripción de genes de mucina se cuantificó por PCR en tiempo real.RESULTADOS. DEP disminuyó significativamente la viabilidad, la proliferación y la secreción de IL-8, pero aumentó la secreción de IL-6 en ambas líneas celulares, HCLE y IOBA-NHC, en forma dosis-dependiente. No se detectó liberación de TNF-a ni en las células ...