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Impact of in vitro Tear Film Composition on Lysozyme Deposition and DenaturationNg, Alan January 2012 (has links)
Purpose
To study the impact of lactoferrin and lipids on the kinetic deposition and denaturation of lysozyme on contact lens materials.
Methods
The contact lenses investigated in this thesis included two silicone hydrogel lenses [AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A] and two conventional hydrogel lenses [ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A]. All lenses were incubated in four solutions: a complex artificial tear solution (ATS); an ATS without lactoferrin; an ATS without lipids; and an ATS without lactoferrin and lipids. Following various time points, all lenses were prepared for lysozyme analysis using the methods below:
• To quantify the kinetic uptake of lysozyme to different contact lens materials, I125-radiolabelled lysozyme was added to each incubation solution. Total lysozyme deposition was quantified using a gamma counter.
• To study the activity of lysozyme deposited to contact lenses, a fluorescence-based lysozyme activity assay was compared to a turbidity assay. Potential interactions with lens materials and extraction solvents were evaluated.
• To investigate the kinetic denaturation of lysozyme deposited to different contact lens materials, the fluorescence-based activity assay and the enzyme-linked immunosorbent assay were used.
Results
The presence of lactoferrin and lipids decreased lysozyme uptake to lotrafilcon B. Lysozyme deposition on senofilcon A was greater in the absence of lipids after day 21, however the opposite was seen with etafilcon A, where lysozyme uptake was lower without lipids in the ATS. Lactoferrin and/or lipids had no effect on lysozyme adsorption to omafilcon A.
The fluorescence-based lysozyme activity assay demonstrated high sensitivity and a wide linear range of detection, which covers the amount of lysozyme typically extracted from contact lenses. Using this assay, lysozyme activity on both silicone hydrogel materials was lower in the presence of lipids in the ATS. In addition, lactoferrin had a protective effect on lysozyme activity for lysozyme sorbed to senofilcon A. Moreover, the presence of lactoferrin and/or lipids did not exhibit any effect on lysozyme denaturation with conventional hydrogel lenses.
Conclusions
The presence of lactoferrin and lipids in an artificial tear solution impacted lysozyme deposition and denaturation of lysozyme on various contact lenses. It is important for in vitro studies, when developing tear film models, to consider the effects of tear film components when investigating protein deposition and denaturation on contact lenses.
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Albertans' preferences for social distance from people with mental illnesses or problemsKlassen, Amy Lynn 11 1900 (has links)
Researchers have noted that the level of contact respondents have with people who have a mental illness and how they attribute responsibility for these conditions contribute to their desire for social distance. Given that the literature suggests that increased contact is associated with reduced social distance and that social distance is highest when individuals are considered personally responsible for their situation, this thesis examines how much of the variation in the desire for social distance is accounted for by both the levels of contact and the attribution of personal responsibility. Ordinary least squares regression was used to analyze the 2007 Alberta Survey (N=1073). Results show that knowing someone, besides oneself, who has received treatment for a mental illness and attributing responsibility for a mental illness onto the individual explain some of the variation in the desire for social distance. The methodological limitations and suggestions for future research are also discussed.
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Effect of antibacterial contact lenses on inflammatory responses in a guinea pig modelVijay, Ajay Kumar, Optometry & Vision Science, Faculty of Science, UNSW January 2007 (has links)
Contact Lens Acute Red Eye (CLARE) and Infiltrative Keratitis (IK) are inflammatory responses of the eye associated with extended wear of soft contact lenses. Bacterial colonization of contact lenses with Gram-negative bacteria such as Pseudomonas aeruginosa is an important risk factor for the development of these adverse responses. Strategies that control the bacterial colonization of contact lenses may help prevent the occurrence of adverse responses. This thesis aimed to develop an animal model of CLARE/IK to test this hypothesis and to test the effectiveness of contact lenses containing antimicrobial compounds, namely silver and furanone compounds, in controlling corneal inflammation caused by Pseudomonas aeruginosa. A guinea pig model of contact lens wear was developed for the study and it was observed that the ocular responses to contact lens wear in the guinea pig were similar to those seen in human eyes wearing contact lenses. Also, three different models for CLARE/IK were developed and tested in the guinea pig eye. The pathological features of CLARE/IK in the guinea pig were virtually identical to those observed in human eyes. Bacterial contamination of contact lenses was confirmed to be a major risk factor for the development of CLARE/IK. Contact lenses containing nano-particles of silver demonstrated very good antibacterial activity against Pseudomonas aeruginosa in-vitro. The silver lenses were able to control the development of CLARE/IK responses in one of the models for CLARE/IK. Silver lenses might be most effective if used to prevent the establishment of a biofilm of bacteria on a lens such as might occur during storage in a contact lens case. Contact lenses were coated with different concentrations of the furanone compounds by physical adsorption and demonstrated good antibacterial activity at higher concentrations. However these concentrations were cytotoxic in-vitro and lower concentrations of furanones did not possess adequate antibacterial activity to control CLARE/IK responses in-vivo. This thesis has successfully demonstrated that guinea pigs can be used to test the effects of extended wear of contact lenses and developed models to test the pathogenesis of adverse responses such as CLARE/IK. The CLARE/IK models developed could be used to further our understanding of the pathogenesis of these inflammatory conditions and explore the activity of other antimicrobials.
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Australian Nonresident Fathers: Attributes influencing their engagement wtih childrenHawthorne, Bruce January 2005 (has links)
Studies of nonresident fathers have largely neglected the influence of their personality on their contact and involvement with children. The present two-stage study, using quantitative and qualitative data collection methods, undertook to investigate the extent to which selected personality characteristics influenced nonresident fathers� continued engagement with children. The study initially collected demographic and personal data from two hundred and sixty nonresident fathers throughout Australia. This first stage of data collection focussed on fathers� experience of the separation and their subsequent frequency and level of contact and their level of involvement with children. It included several multi-item variables, which measured nonresident fathers� relationships with former partners and children, their adjustment to their new parental role, their role satisfaction and role strain. It also included measures of fatherhood salience, nonresident fathers� parental authority within the separated family, their satisfaction with that authority, their attitude to child support and their perception of resident mothers� attitude to contact. It also administered abridged Sensitivity and Impulsivity scales devised by Eysenck (1969). At the second stage of the study, one hundred and thirty-five of these fathers participated in an interview. One hundred and twenty of them completed a personality questionnaire, which measured scores on the four folk scales of Responsibility, Socialization, Self-control and Good Impression, taken from the California Psychological Inventory. The study found Socialization was the only selected personality characteristic to be significantly associated with nonresident fathers� engagement with children. All four folk scales were positively correlated with nonresident fathers� role adjustment, which was significantly associated with nonresident fathers� contact and was part of the model best predicting their involvement with children. Results showed that nonresident fathers� scores on the Sensitivity measure were negatively associated with role adjustment. Most nonresident fathers in the study had frequent contact with children but limited involvement with them. They reported having little scope to share in parental decision making or to be involved in children�s schooling. The study found fatherhood salience, role adjustment, parental authority and attitude to child support to be positively associated with engagement. It showed interparental hostility, interparental conflict and nonresident fathers� role strain to be negatively correlated with engagement. The study also found that dissatisfaction with parental authority within the separated family, role strain and a negative attitude to child support were associated with ongoing interparental hostility. Qualitative data confirmed nonresident fathers� common experience of being marginalised within the family. They also revealed that many participants went to great lengths to maintain some parental relevancy for their children, despite social and legal systems tending to impede them from meeting parental responsibilities and caring for their children.
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Rolling contact fatigue predictions based on elastic-plastic finite element stress analysis and multiaxial fatigue /Bulusu, Prashant. January 2006 (has links)
Thesis (M.S.)--University of Nevada, Reno, 2006. / "August, 2006." Includes bibliographical references (leaves 38-45). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
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Research on nickel alloy sensitivity /Muteba, Itone. January 1999 (has links) (PDF)
Thesis (M.D.S.)--University of Adelaide, Dental School, 2000. / "April 1999." Includes bibliographical references (leaves 46-51).
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Optimization-based analysis of rigid mechanical systems with unilateral contact and kinetic friction /Gomez, Miguel J., January 2008 (has links)
Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (p. 91-97).
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Using corneal characteristics to predict corneal change in overnight orthokeratology /Glavine, Kristin Ann. January 2009 (has links) (PDF)
Thesis (M.S.)--New England College of Optometry, 2009. / Includes bibliographical references (p. 94-96).
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Experimental and theoretical investigation of contact resistance and reliability of lateral contact type ohmic MEMS relaysAlmeida, Lia. Ramadoss, Ramesh. January 2006 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2006. / Abstract. Includes bibliographic references (p.55-59).
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Topological invariants of contact structures and planar open booksArıkan, Mehmet Fırat. January 2008 (has links)
Thesis (Ph. D.)--Michigan State University. Dept. of Mathematics, 2008. / Title from PDF t.p. (viewed on July 23, 2009) Includes bibliographical references (p. 106-108). Also issued in print.
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