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Break-up Time (break-up + time)
Selected AbstractsMorphology in Immiscible Polymer Blends During Solidification of an Amorphous Dispersed Phase under ShearingTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2002Yves Deyrail Abstract Solidification under shear of dispersed polycarbonate (PC) fibers in copolymer polyethylene-methyl acrylate matrix (EMA) was investigated using a hot optical shear device. First, the deformation of PC droplets and its modeling under isothermal conditions were studied for comprehension purposes. Overall agreement with literature models was found and the main influence of the viscosity ratio has been stressed. Second, the morphology control through dynamic quenching was experimented. It consists of solidifying the amorphous PC dispersed phase under shear flow. Break-up times of PC fibers were taken into account. Shear rate and quenching-time balance was demonstrated. Thus, during dynamic solidification, a fibrillar morphology could be obtained through rapid quenching. Long quenching times allow nodular morphology, whose size depends on the shear rate used. PC rods can be obtained by adjusting the shear rate during dynamic quenching. La solidification sous cisaillement du polycarbonate (PC) dispersé dans une matrice copolymère éthylène-acétate de vinyle (EMA) a été suivie à l'aide d'un microscope et d'une platine de cisaillement chauffante. Dans un premier temps la déformation isotherme de billes de PC pour différentes températures a été étudiée, ainsi que sa modélisation. Une bonne corrélation avec les modèles issus de la littérature a été obtenue. L'importance du rapport des viscosités a été ainsi soulignée. Dans un second temps le contrôle de la morphologie par le procédé de « refroidissement dynamique » a été expérimenté. Celui-ci consiste à solidifier le PC sous cisaillement pendant le refroidissement. Les temps de rupture des fibres de PC ont été considérés et l'importance du couple gradient de cisaillement-temps de refroidissement sur le contrôle de la morphologie a été mis en évidence. Pendant la solidification, un refroidissement rapide permet d'obtenir une morphologie fibrillaire. [source] Comparison of indices of vitamin A status in children with chronic liver disease,HEPATOLOGY, Issue 4 2005Andrew P. Feranchak Malabsorption of fat-soluble vitamins is a major complication of chronic cholestatic liver disease. The most accurate way to assess vitamin A status in children who have cholestasis is unknown. The goal of this study was to assess the accuracy of noninvasive tests to detect vitamin A deficiency. Children with chronic cholestatic liver disease (n = 23) and noncholestatic liver disease (n = 10) were studied. Ten cholestatic patients were identified as vitamin A,deficient based on the relative dose response (RDR). Compared with the RDR, the sensitivity and specificity to detect vitamin A deficiency for each test was, respectively: serum retinol, 90% and 78%; retinol-binding protein (RBP), 40% and 91%; retinol/RBP molar ratio, 60% and 74%; conjunctival impression cytology, 44% and 48%; slit-lamp examination, 20% and 66%; tear film break-up time, 40% and 69%; and Schirmer's test, 20% and 78%. We developed a modified oral RDR via oral coadministration of d-alpha tocopheryl polyethylene glycol-1000 succinate and retinyl palmitate. This test had a sensitivity of 80% and a specificity of 100% to detect vitamin A deficiency. In conclusion, vitamin A deficiency is relatively common in children who have chronic cholestatic liver disease. Our data suggest that serum retinol level as an initial screen followed by confirmation with a modified oral RDR test is the most effective means of identifying vitamin A deficiency in these subjects. (HEPATOLOGY 2005;42:782,792.) [source] 3223: Dry eye syndrome and omega-3 fatty acidsACTA OPHTHALMOLOGICA, Issue 2010T KAERCHER Purpose Dry eye disease is characterized by an inflammatory component of the ocular surface. Pathways to modulate inflammation include corticoids and cyclosporine. Omega-3 fatty acids like eicosapentaenoic acid and docosahexaenoic acid represent an alternate pharmacologic way to influence the inflammatory cascade. Methods Clinical studies. Results An epidemiologic study in 32.470 healthy women showed that those with a higher intake of omega-3 fatty acids had a 68% decreased prevalence of dry eye syndrome. Hyposecretory dry eye was tested after intake of omega-3 fatty acids for 45 days. Symptoms, signs and inflammatory markers like HLA-DR improved. Hyperevaporative dry eye improved after a long-term supplementation with omega-3 fatty acids with respect to symptoms, break-up time and meibom score. Patients with refractive surgery (PRK) improved after omega-3 fatty acids intake; this was derived from the OSDI-score, Schirmer I test and tear clearance. In 102 contact-lens wearers the symptoms and signs of dry eye improved after 12 weeks therapy with omega-3 fatty acids. Conclusion Nutricionals with omega-3 fatty acids show evidence-based effects on the inflammatory component of ocular surface disease and tear film disorder. Their beneficial effect was tested for hypovolemic and hyperevaporative dry eye. Patients after refractive surgery and contact lens wearers improved after supplementation, too. In contrast to the available anti-inflammatory therapy the supplementation is apt for a long-term application. [source] Switching from a preserved to a preservative-free prostaglandin preparation in topical glaucoma medicationACTA OPHTHALMOLOGICA, Issue 3 2010Hannu Uusitalo Abstract. Purpose:, The purpose of this study was to investigate the tolerability and intraocular pressure (IOP) reducing effect of the first preservative-free prostaglandin tafluprost (Taflotan®) in patients exhibiting ocular surface side-effects during latanoprost (Xalatan®) treatment. Methods:, A total of 158 patients were enrolled in this open-label multicentre study. Eligible patients had to have at least two ocular symptoms, or one sign and one symptom, during treatment with latanoprost. At baseline, the patients were directly switched from latanoprost to preservative-free tafluprost for 12 weeks. The patients were queried for ocular symptoms, and ocular signs were assessed by using tear break-up time, Schirmer's test, fluorescein staining and evaluation of conjunctival hyperaemia and blepharitis. In addition, HLA-DR and MUC5AC in conjunctival impression cytology specimens were analyzed, and a drop discomfort/quality of life (QoL) questionnaire was employed. IOP was measured at all visits. Results:, Preservative-free tafluprost maintained IOP at the same level after 12- weeks treatment (16.4 ± 2.7 mmHg) as latanoprost at baseline (16.8 ± 2.5 mmHg). During treatment with preservative-free tafluprost, the number of patients having irritation/burning/stinging (56.3%), itching (46.8%), foreign body sensation (49.4%), tearing (55.1%) and dry eye sensation (64.6%) decreased to 28.4%, 26.5%, 27.1%, 27.1% and 39.4% correspondingly. The number of the patients with abnormal fluorescein staining of cornea (81.6%) and conjunctiva (84.2%), blepharitis (60.1%), conjunctival hyperaemia (84.2%) and abnormal Schirmer's test (71.5%) was also reduced significantly to 40.6%, 43.2%, 40.6%, 60.0% and 59.4% correspondingly. The tear break-up time improved significantly from 4.5 ± 2.5 seconds to 7.8 ± 4.9 seconds. A reduction in the number of patients with abnormal conjunctival cells based on HLA-DR and MUC5AC was also detected. Conclusions:, Preservative-free tafluprost maintained IOP at the same level as latanoprost, but was better tolerated in patients having signs or symptoms while on preserved latanoprost. Preservative-free tafluprost treatment resulted in improved QoL, increased patient satisfaction and drop comfort. [source] Conjunctival impression cytology and tear-film changes in patients with familial Mediterranean feverACTA OPHTHALMOLOGICA, Issue 1 2009Aylin Karalezli Abstract. Purpose:, To evaluate the ocular surface changes and tear-film functions in patients with familial Mediterranean fever (FMF). Methods:, This prospective case,control clinical study examined 35 patients with FMF (group 1) and 35 controls (group 2). All patients underwent a full ophthalmological examination. Ocular surface changes were evaluated by determining cell content of surface conjunctival epithelium using conjunctival impression cytology and tear-film functions using Schirmer-I, break-up time (BUT), corneal fluorescein and Rose Bengal tests. Subjective ocular complaints were scored with a four-point scale. Between-group results were compared. Results:, In group 1, impression cytology revealed grade 0 changes in 15 eyes, grade 1 changes in 11 eyes and grade 2 changes in nine eyes in group 1; in group 2, it revealed grade 0 changes in 27 eyes, grade 1 changes in five eyes and grade 2 changes in three eyes (p = 0.013). Mean goblet cell density was 765 ± 45 cells/mm2 in group 1 and 1730 ± 100 cells/mm2 in group 2 (P < 0.001). Mean results on the Schirmer-I test results were 17.36 ± 3.18 mm in group 1 and 19.60 ± 4.17 mm in group 2 (p = 0.364). Mean BUT was 8.20 ± 1.60 seconds in group 1 and 9.93 ± 2.33 seconds in group 2 (p = 0.001). Mean corneal fluorescein and Rose Bengal staining scores were 3.26 ± 1.67 and 0.96 ± 0.71 in group 1 and 1.37 ± 0.34 and 0.40 ± 0.49 in group 2 (p = 0.037, p = 0.005). The presence of subjective ocular complaints was more frequent in group 1 than in group 2. Conclusion:, Despite normal tear production, the ocular surface and tear-film functions of FMF patients differ from those of healthy individuals. These changes may be related to the chronic inflammatory nature of FMF. [source] Tear functions in patients with pingueculaACTA OPHTHALMOLOGICA, Issue 3 2001Halit Oguz ABSTRACT. Purpose: To investigate the tear flow, tear film stability and condition of mucus in patients with pinguecula. Methods: The Schirmer I and ferning tests were performed and break-up time (BUT) was determined in 57 patients with pinguecula [random eyes; 34 males and 23 females, 18 to 70 years of age (mean±SD: 39.1±13.5 years)] and in 57 age-matched subjects (control) [random eyes; 35 males and 22 females, 11 to 70 years of age (mean±SD: 37.8±15.2 years)], and the test results were statistically analysed. Results: The mean Schirmer test value was 22.72±12 mm in the eyes with pinguecula and 22.7±8.5 mm in the control eyes. There was no statistically significant difference (t=0.01, p=0.99) between the groups. The mean BUTs were 11.42±6.89 s in the eyes with pinguecula and 15.46±5.85 s in the control eyes. Comparison of BUTs between the groups revealed a statistically significant difference (t=3.37, p=0.0010). Also, ferning types were found to be significantly abnormal in the eyes with pinguecula (p<0.01). Conclusion: The alteration in the mucin layer is a possible change inducing pinguecula formation, or it may reflect an already existing pathology in the cells on the ocular surface. [source] Alterations of the ocular surface epithelial mucins 1, 2, 4 and the tear functions in patients with atopic keratoconjunctivitisCLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2006M. Dogru Summary Background An increased understanding of the ocular surface alterations at the cellular level in the conjunctiva and the cornea, may help explain the pathogenesis and the subsequent clinical appearance of atopic ocular allergies, which may be potentially blinding. Purpose To investigate MUC 1, 2 and 4 alterations, tear function and the ocular surface disorder in patients with atopic keratoconjunctivitis. Methods Twenty-eight eyes of 14 atopic keratoconjunctivitis patients as well as 22 eyes of 11 age-and sex-matched normal subjects were studied. The subjects underwent corneal sensitivity measurements, Schirmer's test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface, conjunctival impression cytology and brush cytology. Impression cytology samples underwent periodic acid-Schiff and immunohistochemical staining with MUC 1, 2 and 4 antibodies. Brush cytology specimens underwent evaluation for inflammatory cell numbers and quantitative real-time-PCR for MUC 1, 2 and 4 mRNA expression. Patient eyes with fluorescein and Rose Bengal scores greater than four points were regarded to have significant epithelial disease in this study. Results The mean corneal sensitivity and BUT values were significantly lower in atopic patients with significant epithelial disease, compared with patients with insignificant epithelial disease and controls (P<0.01). Brush cytology specimens from patients with significant epithelial disease revealed significantly higher numbers of inflammatory cells (P<0.01). Specimens from patient eyes showed positive staining for MUC 1, 2 and 4. MUC 1, 2 and 4 mRNA expressions were significantly higher in eyes with significant epithelial disease compared with eyes with insignificant epithelial disease and eyes of control subjects. Conclusion Ocular surface inflammation, decline in corneal sensitivity, tear film instability, changes in conjunctival epithelial MUC 1, 2 and 4 mRNA expressions were thought to be important in the pathogenesis of atopic ocular surface disease. [source] | ||||||||||