936 resultados para Biomedical and dental daterials
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Thesis (Ph.D.)--University of Washington, 2016-06
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Thesis (Ph.D.)--University of Washington, 2016-04
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Thesis (Ph.D.)--University of Washington, 2016-06
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Thesis (Master's)--University of Washington, 2016-06
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Thesis (Master's)--University of Washington, 2016-06
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Thesis (Ph.D.)--University of Washington, 2016-06
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This paper evaluates the systematic status of the Antechinus populations of northern New South Wales and southern Queensland, using a combined morphological and molecular (allozymes and mitochondrial DNA) approach. Analysis of the d-loop section of the mitochondrial DNA control region revealed two highly supported clades within A. stuartii sensu lato that were sympatric in the Border Ranges of northern New South Wales. However, genetic distances between these clades were small ( approximately 3%), indicating that time of divergence was probably relatively recent. Allozyme electrophoresis also showed very small differences between clades/ species. Analyses of cranial and dental characters showed that the members of each of these clades differed morphologically and that the clades corresponded to A. stuartii and the recently described A. subtropicus. The combined results support the species status of A. stuartii and A. subtropicus, and suggest that speciation was likely a result of a recent vicariant event.
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Background : Increasing numbers of preschool children are being referred for specialist dental management in a paediatric hospital. Most cases have severe early childhood caries and require comprehensive management under general anaesthesia. The present study investigated risk factors for disease presence at initial consultation. Methods : A convenience sample of 125 children under four years of age from the north Brisbane region were examined and caries experience recorded using dmft and dmfs indices. A self-administered questionnaire obtained information regarding social, demographic, birth, neonatal, infant feeding and dental health behaviour variables. The data were analysed using the chi-square and one-way analysis of variance procedures. Results : Ninety-four per cent of referred children had severe ECC with mean dmft of 10.5 ± 3.8 and mean dmfs of 27.1 ± 15.1. Prevalence of severe ECC was significantly higher in children allowed a sweetened liquid in the infant feeding bottle (99 per cent) and allowed to sip from an infant feeding bottle during the day (100 per cent). Mean dmfs was significantly higher in children allowed to sleep with a bottle (28.7) and sip from a bottle during the day (29.9), children from a non-Caucasian background (31.8), those children that commenced regular toothbrushing between 6 to 12 months of age (28.1), had no current parental supervision of daily tooth-brushing (34.2) and had not taken daily fluoride supplements (27.8), vitamin supplements (27.8) or prescription medicine previously (27.6). Conclusions : The behavioural determinants for severe early childhood caries presence in hospital-referred children were similar to those identified in the regional preschool population.
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Review date: Review period January 1992-December 2001. Final analysis July 2004-January 2005. Background and review context: There has been no rigorous systematic review of the outcomes of early exposure to clinical and community settings in medical education. Objectives of review: (1) Identify published empirical evidence of the effects of early experience in medical education, analyse it, and synthesize conclusions from it. (2) Identify the strengths and limitations of the research effort to date, and identify objectives for future research. Search strategy: Ovid search of. BEI, ERIC, Medline, CIATAHL and EMBASE Additional electronic searches of: Psychinfo, Timelit, EBM reviews, SIGLE, and the Cochrane databases. Hand-searches of: Medical Education, Medical Teacher, Academic Medicine, Teaching and Learning in Medicine, Advances in Health Sciences Education, Journal of Educational Psychology. Criteria: Definitions: Experience: Authentic (real as opposed to simulated) human contact in a social or clinical context that enhances learning of health, illness and/or disease, and the role of the health professional. Early: What would traditionally have been regarded as the preclinical phase, usually the first 2 years. Inclusions: All empirical studies (verifiable, observational data) of early experience in the basic education of health professionals, whatever their design or methodology, including papers not in English. Evidence from other health care professions that could be applied to medicine was included. Exclusions: Not empirical; not early; post-basic; simulated rather than 'authentic' experience. Data collection: Careful validation of selection processes. Coding by two reviewers onto an extensively modified version of the standard BEME coding sheet. Accumulation into an Access database. Secondary coding and synthesis of an interpretation. Headline results: A total of 73 studies met the selection criteria and yielded 277 educational outcomes; 116 of those outcomes (from 38 studies) were rated strong and important enough to include in a narrative synthesis of results; 76% of those outcomes were from descriptive studies and 24% from comparative studies. Early experience motivated and satisfied students of the health professions and helped them acclimatize to clinical environments, develop professionally, interact with patients with more confidence and less stress, develop self-reflection and appraisal skill, and develop a professional identity. It strengthened their learning and made it more real and relevant to clinical practice. It helped students learn about the structure and function of the healthcare system, and about preventive care and the role of health professionals. It supported the learning of both biomedical and behavioural/social sciences and helped students acquire communication and basic clinical skills. There were outcomes for beneficiaries other than students, including teachers, patients, populations, organizations and specialties. Early experience increased recruitment to primary care/rural medical practice, though mainly in US studies which introduced it for that specific purpose as part of a complex intervention. Conclusions: Early experience helps medical students socialize to their chosen profession. It. helps them acquire a range of subject matter and makes their learning more real and relevant. It has potential benefits for other stakeholders, notably teachers and patients. It can influence career choices.
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Purpose: The purpose of this longitudinal study was to determine factors associated with mutans streptococci (MS) infection and development of caries lesions in a group of children 21 to 72 months old. Methods: The 63 caries-free children, recruited since birth, were divided into: (1) a study group of 24 children who were colonized with MS; and (2) a control group of 39 children without MS. The children were recalled every 3 months for approximately 24 months, and their social, medical, and dental histories were updated. At each recall, the teeth were checked for presence or absence of plaque, enamel hypoplasia, and caries lesions, and their MS status was assessed using a commercial test kit. Results: MS infection was associated with: (1) visible plaque (P < .01); (2) enamel hypoplasia (P < .05); (3) commencement of tooth-brushing after 12 months of age (P < .05); (4) lack of parental assistance with tooth-brushing (P < .025); and (5) increased hours of child care/school (P < .05). Four children (20%) were colonized at an age range of 21 to 36 months, 9 (45%) at 37 to 48 months, and 7 (35%) at 49 to 72 months (P < .001). Eight children who developed caries lesions: (1) had more hypoplastic teeth (P < .001); (2) ate sugar-containing snacks (P < .05); and (3) did not brush regularly with chlorhexidine gel (P < .01) compared to those who remained free of caries lesions. Conclusions: Lack of oral hygiene, consumption of sugar-containing snacks, and enamel hypoplasia are significant factors for both MS infection and caries lesion initiation.
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As defined by the European Union, “ ’Nanomaterial’ (NM) means a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or agglomerate, where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm-100 nm ” (2011/696/UE). Given their peculiar physico-chemical features, nanostructured materials are largely used in many industrial fields (e.g. cosmetics, electronics, agriculture, biomedical) and their applications have astonishingly increased in the last fifteen years. Nanostructured materials are endowed with very large specific surface area that, besides making them very useful in many industrial processes, renders them very reactive towards the biological systems and, hence, potentially endowed with significant hazard for human health. For these reasons, in recent years, many studies have been focused on the identification of toxic properties of nanostructured materials, investigating, in particular, the mechanisms behind their toxic effects as well as their determinants of toxicity. This thesis investigates two types of nanostructured TiO2 materials, TiO2 nanoparticles (NP), which are yearly produced in tonnage quantities, and TiO2 nanofibres (NF), a relatively novel nanomaterial. Moreover, several preparations of MultiWalled Carbon Nanotubes (MWCNT), another nanomaterial widely present in many products, are also investigated.- Although many in vitro and in vivo studies have characterized the toxic properties of these materials, the identification of their determinants of toxicity is still incomplete. The aim of this thesis is to identify the structural determinants of toxicity, using several in vitro models. Specific fields of investigation have been a) the role of shape and the aspect ratio in the determination of biological effects of TiO2 nanofibres of different length; b) the synergistic effect of LPS and TiO2 NP on the expression of inflammatory markers and the role played therein by TLR-4; c) the role of functionalization and agglomeration in the biological effects of MWCNT. As far as biological effects elicited by TiO2 NF are concerned, the first part of the thesis demonstrates that long TiO2 nanofibres caused frustrated phagocytosis, cytotoxicity, hemolysis, oxidative stress and epithelial barrier perturbation. All these effects were mitigated by fibre shortening through ball-milling. However, short TiO2 NF exhibited enhanced ability to activate acute pro-inflammatory effects in macrophages, an effect dependent on phagocytosis. Therefore, aspect ratio reduction mitigated toxic effects, while enhanced macrophage activation, likely rendering the NF more prone to phagocytosis. These results suggest that, under in vivo conditions, short NF will be associated with acute inflammatory reaction, but will undergo a relatively rapid clearance, while long NF, although associated with a relatively smaller acute activation of innate immunity cells, are not expected to be removed efficiently and, therefore, may be associated to chronic inflammatory responses. As far as the relationship between the effects of TiO2 NP and LPS, investigated in the second part of the thesis, are concerned, TiO2 NP markedly enhanced macrophage activation by LPS through a TLR-4-dependent intracellular pathway. The adsorption of LPS onto the surface of TiO2 NP led to the formation of a specific bio-corona, suggesting that, when bound to TiO2 NP, LPS exerts a much more powerful pro-inflammatory effect. These data suggest that the inflammatory changes observed upon exposure to TiO2 NP may be due, at least in part, to their capability to bind LPS and, possibly, other TLR agonists, thus enhancing their biological activities. Finally, the last part of the thesis demonstrates that surface functionalization of MWCNT with amino or carboxylic groups mitigates the toxic effects of MWCNT in terms of macrophage activation and capability to perturb epithelial barriers. Interestingly, surface chemistry (in particular surface charge) influenced the protein adsorption onto the MWCNT surface, allowing to the formation of different protein coronae and the tendency to form agglomerates of different size. In particular functionalization a) changed the amount and the type of proteins adsorbed to MWCNT and b) enhanced the tendency of MWCNT to form large agglomerates. These data suggest that the different biological behavior of functionalized and pristine MWCNT may be due, at least in part, to the different tendency to form large agglomerates, which is significantly influenced by their different capability to interact with proteins contained in biological fluids. All together, these data demonstrate that the interaction between physico-chemical properties of nanostructured materials and the environment (cells + biological fluids) in which these materials are present is of pivotal importance for the understanding of the biological effects of NM. In particular, bio-persistence and the capability to elicit an effective inflammatory response are attributable to the interaction between NM and macrophages. However, the interaction NM-cells is heavily influenced by the formation at the nano-bio interface of specific bio-coronae that confer a novel biological identity to the nanostructured materials, setting the basis for their specific biological activities.
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Previous research has indicated that the majority of the UK dentate population suffers from dental disease. This problem was examined in terms of the supply of, and demand for, dental treatment: how might the uptake of dental services be increased and dental health improved? The target population for the main survey was adolescents among whom demand for dental treatment has decreased. In 524 adolescents surveyed, fear of pain was the major deterrent to regular dental visits. The theoretical literature was explored for illuminating and practical approaches to the problem. The theory of reasoned action developed by Fishbein seemed the most promising. This theory was tested and validated on the adolescent sample identifying clear differences between regular and irregular dental attenders which could be usefully exploited by dental health education. A repertory grid analysis study further illuminated perceptions of dental treatment. A survey of a random sample of 716 dentists revealed that most dentists were in favour of delegating work to auxiliary help but few could do so. Auxiliary help would increase supply of services: data revealed an encouraging trend for younger dentists to be more in favour of delegation than older dentists. A survey was carried out of computer systems available for dentists suggesting that this might reduce the need for clerical assistance but would not ususally affect the supply of treatment. However in some dental practices computerisation might increase demand. For example a personalised reminder was developed and evaluated in a controlled study of 938 appointments demonstrating an uptake in dental services. Conclusions are that demand for treatment can be increased in various ways especially by teaching dentists' behavioural strategies to deal with fear and pain. Various recommendations on this are made. If demand were to outstrip supply increased delegation to auxiliary help could provide a viable way of increasing supply.
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Biomimetic hydroxyapatite was synthesized by the controlled release of calcium and phosphate ions from poly(N-isopropylacrylamide-co-acrylic acid) (poly(NIPAAm-co-AA)) nanogels. Mixing nanogels containing calcium chloride (CaCl2 ·2H2O) and nanogels containing sodium hydrogen phosphate (Na2HPO4·2H2O) in simulated body fluid (SBF) at physiological conditions of 37 °C and pH 7.4, biomimetic hydroxyapatite was obtained. By studying separately the loading and controlled release of the salts from the nanogels, adequate conditions were chosen to synthesize the hydroxyapatite: Calcium loaded (Ca-loaded) nanogels (1000 mg/ml; 400:3) and inorganic phosphate loaded (Pi-loaded) nanogels (90 mg/ml; 12:1) in a ratio of 2:1 were placed in SBF solution. The obtained powders characterization showed that a low crystalline and substituted hydroxyapatite similar to bone apatite was formed. Such a strategy could be used in medical and dental procedures to induce rapid inorganic mineral formation from a nanogel-containing biomaterial. © 2012 American Scientific Publishers. All rights reserved.
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The devising of a general engineering theory of multifunctional diagnostic systems for non-invasive medical spectrophotometry is an important and promising direction of modern biomedical engineering. We aim in this study to formalize in scientific engineering terms objectives for multifunctional laser non-invasive diagnostic system (MLNDS). The structure-functional model as well as a task-function of generalized MLNDS was formulated and developed. The key role of the system software for MLNDS general architecture at steps of ideological-technical designing has been proved. The basic principles of block-modules composition of MLNDS hardware are suggested as well. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).