| 64731. |
- McLaughlin, Christopher R., et al.
(författare)
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Bioengineered corneas for transplantation and in vitro toxicology
- 2009
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Ingår i: Frontiers in Bioscience. - : Frontiers in Bioscience. - 1093-9946 .- 1093-4715. ; 14, s. 3326-3337
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Tidskriftsartikel (refereegranskat)abstract
- Bioengineered corneas have been designed to replace partial or the full-thickness of defective corneas, as an alternative to using donor tissues. They range from prosthetic devices that solely address replacement of the corneas function, to tissue engineered hydrogels that permit regeneration of host tissues. In cases where corneal stem cells have been depleted by injury or disease, most frequently involving the superficial epithelium, tissue engineered lamellar implants reconstructed with stem cells have been transplanted. In situ methods using ultraviolet A (UVA) crosslinking have also been developed to strengthen weakened corneas. In addition to the clinical need, bioengineered corneas are also rapidly gaining importance in the area of in vitro toxicology, as alternatives to animal testing. More complex, fully innervated, physiologically active, three-dimensional organotypic models are also being tested.
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| 64732. |
- McLaughlin, Christopher, et al.
(författare)
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Regeneration of Corneal Cells and Nerves in an Implanted Collagen Corneal Substitute
- 2008
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Ingår i: Cornea. - 0277-3740 .- 1536-4798. ; 27:5, s. 580-589
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Our objective was to evaluate promotion of tissue regeneration by extracellular matrix (ECM) mimics, by using corneal implantation as a model system.METHODS: Carbodiimide cross-linked porcine type I collagen was molded into appropriate corneal dimensions to serve as substitutes for natural corneal ECM. These were implanted into corneas of mini-pigs after removal of the host tissue, and tracked over 12 months, by clinical examination, slit-lamp biomicroscopy, in vivo confocal microscopy, topography, and esthesiometry. Histopathology and tensile strength testing were performed at the end of 12 months. Other samples were biotin labeled and implanted into mice to evaluate matrix remodeling.RESULTS: The implants promoted regeneration of corneal cells, nerves, and the tear film while retaining optical clarity. Mechanical testing data were consistent with stable, seamless host-graft integration in regenerated corneas, which were as robust as the untreated fellow corneas. Biotin conjugation is an effective method for tracking the implant within the host tissue.CONCLUSIONS: We show that a simple ECM mimetic can promote regeneration of corneal cells and nerves. Gradual turnover of matrix material as part of the natural remodeling process allowed for stable integration with host tissue and restoration of mechanical properties of the organ. The simplicity in fabrication and shown functionality shows potential for ECM
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| 64733. |
- McLaughlin, CR, et al.
(författare)
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Regeneration of functional nerves within full thickness collagen-phosphorylcholine corneal substitute implants in guinea pigs
- 2010
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 31:10, s. 2770-2778
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Tidskriftsartikel (refereegranskat)abstract
- Our objective was to evaluate promotion of tissue and nerve regeneration by extracellular matrix (ECM) Mimics, using corneal implantation as a model system. Porcine type I collagen and 2-methacryloyloxyethyl phosphorylcholine (MPC) were crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) and moulded into appropriate corneal dimensions to serve as substitutes for natural corneal ECK These were implanted as full thickness grafts by penetrating keratoplasty into the corneas Of guinea pigs after removal of the host tissue, and tracked over eight months, by clinical examination, slit-lamp biomicroscopy, and esthesiometry. Histopathology and ex vivo nerve terminal impulse recordings were performed at three months and at eight months. The implants promoted regeneration of corneal cells, nerves and the tear film, while retaining optical clarity. After three months, electrophysiological recordings showed evidence of mechano-nociceptors, and polymodal units inside the implants, while cold-sensitive units were present only on the peripheral host cornea. Following eight months, the incidence of nerve activity and the frequency of spontaneous firing were higher than in control eyes as reported for regenerating fibers. Active cold nerve terminals also innervated the implant area. We show that ECM mimetic materials can promote regeneration of corneal cells and functional nerves. The simplicity in fabrication and demonstrated functionality shows potential for ECM substitutes in future clinical applications. (C) 2009 Elsevier Ltd. All rights reserved.
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| 64734. |
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| 64735. |
- McLean, D., et al.
(författare)
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Cancer mortality in workers exposed to organochlorine compounds in the pulp and paper industry : An international collaborative study
- 2006
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Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 114:7, s. 1007-1012
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to evaluate cancer mortality in pulp and paper industry workers exposed to chlorinated organic compounds. We assembled a multinational cohort of workers employed between 1920 and 1996 in 11 countries. Exposure to both volatile and nonvolatile organochlorine compounds was estimated at the department level using an exposure matrix. We conducted a standardized mortality ratio (SMR) analysis based on age and calendar-period-specific national mortality rates and a Poisson regression analysis. The study population consisted of 60,468 workers. Workers exposed to volatile organochlorines experienced a deficit of all-cause [SMR = 0.91, 95% confidence interval (CI), 0.89-0.93] and all-cancer (SMR = 0.93, 95% CI, 0.89-0.97) mortality, with no evidence of increased risks for any cancer of a priori interest. There was a weak, but statistically significant, trend of increasing risk of all-cancer mortality with increasing weighted cumulative exposure. A similar deficit in all-cause (SMR = 0.94, 95% CI, 0.91-0.96) and all-cancer (SMR = 0.94, 95% CI, 0.89-1.00) mortality was observed in those exposed to nonvolatile organochlorines. No excess risk was observed in cancers of a priori interest, although mortality from Hodgkin disease was elevated (SMR = 1.76, 95% CI, 1.02-2.82). In this study we found little evidence that exposure to organochlorines at the levels experienced in the pulp and paper industry is associated with an increased risk of cancer, apart from a weak but significant association between all-cancer mortality and weighted cumulative volatile organochlorine exposure.
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| 64736. |
- McLean, Richard S, et al.
(författare)
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Failure of Continuous Improvement initiatives in manufacturing environments: : A systematic review of the evidence
- 2017
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Ingår i: Total Quality Management and Business Excellence. - : Routledge. - 1478-3363 .- 1478-3371. ; 28:3-4, s. 219-237
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Tidskriftsartikel (refereegranskat)abstract
- Continuous Improvement initiatives put in place the necessary elements to allow an organisation to identify and implement improvements on an ongoing basis. Structured approaches to quality and process improvement started with total quality managenment, and developed with Lean Manufacturing, Six Sigma, and Lean Six Sigma. Despite the benefits these can bring, Continuous Improvement efforts are consistently reported to have a high failure rate. Research, however, regularly focuses on success factors rather than directly addressing failures, and as a result, failure factors are currently fragmented. The objective of this paper is to provide a systematic literature review detailing why Continuous Improvement initiatives within manufacturing environments may fail. The paper describes the systematic review protocol followed and reasoning associated. From the 72 journal articles selected, it is evident that initiatives can fail due to a multitude of individual variables. The main contribution of the paper is the grouping of these under eight core themes: Motives & Expectations, Culture & Environment, Management Leadership, Implementation Approach, Training, Project Management, Employee Involvement Levels, and Feedback & Results. The findings provide insight regarding the complexity of organisational change involving Continuous Improvement implementation. The need for future research to develop the themes into a framework is also discussed.
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| 64737. |
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| 64738. |
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| 64739. |
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| 64740. |
- McNamara, Paul N, et al.
(författare)
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Tissue viability (TiVi) imaging: temporal effects of local occlusion studies in the volar forearm
- 2010
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Ingår i: Journal of Biophotonics. - : John Wiley & Sons. - 1864-063X .- 1864-0648. ; 3:1-2, s. 66-74
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Tidskriftsartikel (refereegranskat)abstract
- Tissue Viability (TiVi) imaging is a promising new technology for the assessment of microcirculation in the upper human dermis. Although the technique is easily implemented and develops large amounts of observational data, its role in the clinical workplace awaits the development of standardised protocols required for routine clinical practice. The present study investigates the use of TiVi technology in a human, in vivo, localized, skin blood flow occlusion protocol. In this feasibility study, the response of the cutaneous microcirculation after provocation on the volar surface of the forearm was evaluated using a high temporal-low spatial resolution TiVi camera. 19 healthy subjects - 10 female and 9 male - were studied after a localized pressure was applied for 5 different time periods ranging from 5 to 25 seconds. Areas corresponding to 100 x 100 pixels (2.89 cm(2)) were monitored for 60 seconds prior to, during and after each occlusion period. Our results demonstrated the removal of blood from the local area and a hyperaemic response supporting the suitability of TiVi imaging for the generation of detailed provocation response data of relevance for the physiological function of the skin microcirculation in health and disease.
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