The Effect of Architecture and Shear Stress on Endothelialization of 3D Printed Vascular Networks

Despite significant progress in the field of tissue engineering within the last decade, a number of unsolved problems still remain. One of the most relevant issues is the lack of proper vascularization that limits the size of engineered tissues to smaller than clinically relevant dimensions. In particular, the growth of engineered tissue in vitro within bioreactors is plagued with this challenge. Specifically, the tubular perfusion system bioreactor has been used for large scale bone constructs; however these engineered constructs lack inherent vasculature and quickly develop a hypoxic core, where no nutrient exchange can occur, thus leading to cell death. Through the use of 3D printed vascular templates in conjunction with a tubular perfusion system bioreactor, we attempt to create an endothelial cell monolayer on 3D scaffolds that could potentially serve as the foundation of inherent vasculature within these engineered bone grafts.

Establishment of a protocol for the cryopreservation of cell sheets of adipose tissue stem cells

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2016

The Role of Epstein-Barr Virus LMP-1 Immunohistochemical Staining in Childhood Hodgkin Lymphoma

Background: There are a few published studies about prognostic markers of Epstein-B virus (EBV) related to outcomes in pediatric Hodgkin Lymphoma (HL). Objectives: We aimed to investigate the prognostic value and effect of EBV on survival by using biopsy materials in children and adolescents diagnosed with HL. Patients and Methods: EBV LMP-1 expression was examined using immunohistochemical methods in 58 tumor samples. Clinical features, overall survival (OS) and failure free survival time (FFS) were compared between EBV LMP-1 positive and negative patients. Results: In 20 (35%) patients tumors were LMP-1 positive. When compared with patients above 10 years old, EBV LMP-1 was often positive in patients under 10 years old (30% vs. 70%, P = 0.02). In our most cases having B symptoms and advanced stage, EBV positiveness in Hodgkin Reed-Stenberg cells (H-RS) was not a significant determinant for survival (P = 0.78). Half of the past clinical trials in childhood HL reported longer survival rates in EBV LMP-1 positive patients. In some trials similar to our results there was no significant relationship between EBV and prognosis. Conclusions: The reason of diminished EBV positiviness may be related to technical methods such as not using immunohistochemical and in situ hybridization for EBER antigen but in laboratory conditions painting of control tissues with EBV impair this probability. In addition, cases enrolled to our study were living in Istanbul where social and economical factors are improved rather than generally.

Étude paléopathologique préliminaire à travers l'analyse macroscopique et scanographique : exemple du cimetière St. Matthew, ville de Québec (1771-1860)

Sachant que plusieurs maladies entrainent des lésions qui ne sont pas toujours observables à l’oeil, cette étude préliminaire en paléopathologie humaine utilise une approche complémentaire issue de l’imagerie médicale, le ct-scan, afin de fournir des diagnostics plus précis. L’objectif est donc de tester ici l’efficacité et les limites de l’analyse scanographique durant l’analyse de spécimens archéologiques. Un échantillon de 55 individus a été sélectionné à partir de la collection ostéologique provenant du cimetière protestant St. Matthew (ville de Québec, 1771 – 1860). Une analyse macroscopique et scanographique complète a alors été effectuée sur chaque squelette. Les observations macroscopiques ont consisté à enregistrer une dizaine de critères standardisés par la littérature de référence en lien avec des manifestations anormales à la surface du squelette. Les ct-scans ont été réalisés à l’Institut National de la Recherche Scientifique de la Ville de Québec avec un tomodensitomètre Somatom de Siemens (définition AS+ 128). Les données scanographiques ont permis d’enregistrer une série de critères complémentaires sur la structure interne de l’os (amincissement/épaississement de la corticale, variation de densité, etc.) Selon la méthode du diagnostic différentiel, des hypothèses ou diagnostics ont été proposés. Ils sont principalement basés sur les critères diagnostiques mentionnés dans les manuels de référence en paléopathologie, mais aussi à l’aide de la littérature clinique et l’expertise de médecins. Les résultats présentés ici supportent que: 1) Dans 43% des cas, les données scanographiques ont apporté des informations essentielles dans la diagnose pathologique. Cette tendance se confirme en fonction de certaines maladies, mais pas d’autres, car certains diagnostics ne peuvent se faire sans la présence de tissus mous. 2) La distribution spatiale de la plupart des lésions varie selon les régions anatomiques, aussi bien en macroscopie qu’en scanographie. 3) Certains types de maladie semblent associés à l’âge et au sexe, ce qui est conforté par la littérature. 4) Cette recherche démontre aussi que le processus de diagnose nécessite, dans 38% des cas, une analyse complémentaire (ex. histologie, scintigraphie, radiographie) pour préciser le diagnostic final.

Étude paléopathologique préliminaire à travers l'analyse macroscopique et scanographique : exemple du cimetière St. Matthew, ville de Québec (1771-1860)

Sachant que plusieurs maladies entrainent des lésions qui ne sont pas toujours observables à l’oeil, cette étude préliminaire en paléopathologie humaine utilise une approche complémentaire issue de l’imagerie médicale, le ct-scan, afin de fournir des diagnostics plus précis. L’objectif est donc de tester ici l’efficacité et les limites de l’analyse scanographique durant l’analyse de spécimens archéologiques. Un échantillon de 55 individus a été sélectionné à partir de la collection ostéologique provenant du cimetière protestant St. Matthew (ville de Québec, 1771 – 1860). Une analyse macroscopique et scanographique complète a alors été effectuée sur chaque squelette. Les observations macroscopiques ont consisté à enregistrer une dizaine de critères standardisés par la littérature de référence en lien avec des manifestations anormales à la surface du squelette. Les ct-scans ont été réalisés à l’Institut National de la Recherche Scientifique de la Ville de Québec avec un tomodensitomètre Somatom de Siemens (définition AS+ 128). Les données scanographiques ont permis d’enregistrer une série de critères complémentaires sur la structure interne de l’os (amincissement/épaississement de la corticale, variation de densité, etc.) Selon la méthode du diagnostic différentiel, des hypothèses ou diagnostics ont été proposés. Ils sont principalement basés sur les critères diagnostiques mentionnés dans les manuels de référence en paléopathologie, mais aussi à l’aide de la littérature clinique et l’expertise de médecins. Les résultats présentés ici supportent que: 1) Dans 43% des cas, les données scanographiques ont apporté des informations essentielles dans la diagnose pathologique. Cette tendance se confirme en fonction de certaines maladies, mais pas d’autres, car certains diagnostics ne peuvent se faire sans la présence de tissus mous. 2) La distribution spatiale de la plupart des lésions varie selon les régions anatomiques, aussi bien en macroscopie qu’en scanographie. 3) Certains types de maladie semblent associés à l’âge et au sexe, ce qui est conforté par la littérature. 4) Cette recherche démontre aussi que le processus de diagnose nécessite, dans 38% des cas, une analyse complémentaire (ex. histologie, scintigraphie, radiographie) pour préciser le diagnostic final.

Unraveling the function of bacterial-type phosphoenolpyruvate carboxylase in vascular plants

Thesis (Master, Biology) -- Queen's University, 2016-09-29 20:09:46.997

Retalho de reposicionamento coronal vs.técnica de tunelização para recobrimento radicular

Introdução: Ao longo da última década a procura por um sorriso estético (inclui harmonia e continuidade de forma) transformou-se numa preocupação relevante na Medicina Dentária e em particular nos tratamentos periodontais. As recessões gengivais com as consequentes exposições radiculares e alteração morfológica dos tecidos periodontais, podem constituir um problema estético importante podendo trazer outros problemas associados. Objetivo: O objetivo deste trabalho é identificar qual a técnica cirúrgica mais vantajosa para recobrimento radicular (RRC, RRC com ETC e TUN) e saber em que situações uma poderá ser melhor escolha que a outra, sabendo que ambas são técnicas de alta fiabilidade. Materiais e métodos: Para o cumprimento do objetivo, foi desenvolvida uma pesquisa entre Junho e Setembro de 2016, de artigos em português e inglês, sem limites temporais, recorrendo às bases de dados electrónicas: PUBMED e Google Académico utilizando para o efeito as seguintes “palavras-chave”: “tunnel technique”, “microsurgery”, “recession coverage”, “connective tissue graft”, “coronally advanced flap”, “coronally advanced flap vs. tunnel technique”. Foram utilizados 40 artigos científicos e duas obras literárias (Clinical Periodontology and Implant Dentistry e Plastic-Esthetic Periodontal and Implant Surgery) para complementar o tema. Conclusão: Segundo a literatura publicada e consultada, os procedimentos mais eficazes são aqueles que utilizam enxertos de tecido conjuntivo para o aumento da espessura gengival. Sendo que comparando as duas técnicas Retalho de Reposicionamento Coronal e Técnica de Tunelização, a segunda leva vantagem em relação à primeira, uma vez que, necessitando de menos incisões trará aspetos positivos quanto à cicatrização pois permite maior aporte sanguíneo, além de haver uma preservar das papilas.

Clypeotheca, a new skeletal structure in scleractinian corals : a potential stress indicator

Physiological responses to environmental stress are increasingly well studied in scleractinian corals. This work reports a new stress-related skeletal structure we term clypeotheca. Clypeotheca was observed in several livecollected common reef-building coral genera and a two to three kya subfossil specimen from Heron Reef, Great Barrier Reef and consists of an epitheca-like skeletal wall that seals over the surface of parts of the corallum in areas of stress or damage. It appears to form from a coordinated process wherein neighboring polyps and adjoining coenosarc seal themselves off from the surrounding environment as they contract and die. Clypeotheca forms from inward skeletal centripetal growth at the edges of corallites and by the merging of flange-like outgrowths that surround individual spines over the surface of the coenosteum. Microstructurally, the merged flanges are similar to upsidedown dissepiments and true epitheca. Clypeotheca is interpreted primarily as a response to stress that may help protect the colony from invasion of unhealthy tissues by parasites or disease by retracting tissues in areas that have become unhealthy for the polyps. Identification of skeletal responses of corals to environmental stress may enable the frequency of certain types of environmental stress to be documented in past environments. Such data may be important for understanding the nature of reef dynamics through intervals of climate change and for monitoring the effects of possible anthropogenic stress in modern coral reef habitats.

Enterprise systems curricula for Asia-Pacific region : a vision for 2020

Enterprise Systems (ES) have emerged as possibly the most important and challenging development in the corporate use of information technology in the last decade. Organizations have invested heavily in these large, integrated application software suites expecting improvments in; business processes, management of expenditure, customer service, and more generally, competitiveness, improved access to better information/knowledge (i.e., business intelligence and analytics). Forrester survey data consistently shows that investment in ES and enterprise applications in general remains the top IT spending priority, with the ES market estimated at $38 billion and predicted to grow at a steady rate of 6.9%, reaching $50 billion by 2012 (Wang & Hamerman, 2008). Yet, organizations have failed to realize all the anticipated benefits. One of the key reasons is the inability of employees to properly utilize the capabilities of the enterprise systems to complete the work and extract information critical to decision making. In response, universities (tertiary institutes) have developed academic programs aimed at addressing the skill gaps. In parallel with the proliferation of ES, there has been growing recognition of the importance of Teaching Enterprise Systems at tertiary education institutes. Many academic papers have discused the important role of Enterprise System curricula at tertiary education institutes (Ask, 2008; Hawking, 2004; Stewart, 2001), where the teaching philosophises, teaching approaches and challenges in Enterprise Systems education were discussed. Following the global trends, tertiary institutes in the Pacific-Asian region commenced introducing Enterprise System curricula in late 1990s with a range of subjects (a subject represents a single unit, rather than a collection of units; which we refer to as a course) in faculties / schools / departments of Information Technology, Business and in some cases in Engineering. Many tertiary educations commenced their initial subject offers around four salient concepts of Enterprise Systems: (1) Enterprise Systems implementations, (2) Introductions to core modules of Enterprise Systems, (3) Application customization using a programming language (e.g. ABAP) and (4) Systems Administration. While universities have come a long way in developing curricula in the enterprise system area, many obstacles remain: high cost of technology, qualified faculty to teach, lack of teaching materials, etc.

Nitric oxide synthase type-II is synthesized by human gingival tissue and cultured human gingival fibroblasts

Nitric oxide is known to be an important inflammatory mediator, and is implicated in the pathophysiology of a range of inflammatory disorders. The aim of this study was to determine the localization and distribution of endothelial NOS (NOS-II) in human gingival tissue, and to ascertain if human gingival fibroblasts express NOS-II when stimulated with interferon gamma (IFN-gamma) and bacterial lipopolysaccharide (LPS). The distribution of NOS-II in inflamed and non-inflamed specimens of human gingivae was studied using a monoclonal antibody against nitric oxide synthase II. Cultures of fibroblasts derived from healthy human gingivae were used for the cell culture experiments. The results from immunohistochemical staining of the tissues indicated an upregulation of NOS-II expression in inflamed compared to non-inflamed gingival tissue. Fibroblasts and inflammatory cells within the inflamed connective tissue were positively stained for NOS-II. In addition, basal keratinocytes also stained strongly for NOS-II, in both healthy and inflamed tissue sections. When cultured human gingival fibroblasts were stimulated by INF-gamma and Porphyromonas gingivalis LPS, NOS-II was more strongly expressed than when the cells were exposed to LPS or IFN-gamma alone. These data suggest that, as for other inflammatory diseases, NO plays a role in the pathophysiology of periodontitis.

An investigation into factors affecting electron density calibration for a megavoltage cone-beam CT system

There is a growing interest in the use of megavoltage cone-beam computed tomography (MV CBCT) data for radiotherapy treatment planning. To calculate accurate dose distributions, knowledge of the electron density (ED) of the tissues being irradiated is required. In the case of MV CBCT, it is necessary to determine a calibration-relating CT number to ED, utilizing the photon beam produced for MV CBCT. A number of different parameters can affect this calibration. This study was undertaken on the Siemens MV CBCT system, MVision, to evaluate the effect of the following parameters on the reconstructed CT pixel value to ED calibration: the number of monitor units (MUs) used (5, 8, 15 and 60 MUs), the image reconstruction filter (head and neck, and pelvis), reconstruction matrix size (256 by 256 and 512 by 512), and the addition of extra solid water surrounding the ED phantom. A Gammex electron density CT phantom containing EDs from 0.292 to 1.707 was imaged under each of these conditions. The linear relationship between MV CBCT pixel value and ED was demonstrated for all MU settings and over the range of EDs. Changes in MU number did not dramatically alter the MV CBCT ED calibration. The use of different reconstruction filters was found to affect the MV CBCT ED calibration, as was the addition of solid water surrounding the phantom. Dose distributions from treatment plans calculated with simulated image data from a 15 MU head and neck reconstruction filter MV CBCT image and a MV CBCT ED calibration curve from the image data parameters and a 15 MU pelvis reconstruction filter showed small and clinically insignificant differences. Thus, the use of a single MV CBCT ED calibration curve is unlikely to result in any clinical differences. However, to ensure minimal uncertainties in dose reporting, MV CBCT ED calibration measurements could be carried out using parameter-specific calibration measurements.

Synthetic rating system for railway bridge management

Railway bridges deteriorate with age. Factors such as environmental effects on different materials of a bridge, variation of loads, fatigue, etc will reduce the remaining life of bridges. Bridges are currently rated individually for maintenance and repair actions according to the structural conditions of their elements. Dealing with thousands of bridges and several factors that cause deterioration, makes the rating process extremely complicated. Current simplified but practical rating methods are not based on an accurate structural condition assessment system. On the other hand, the sophisticated but more accurate methods are only used for a single bridge or particular types of bridges. It is therefore necessary to develop a practical and accurate system which will be capable of rating a network of railway bridges. This paper introduces a new method for rating a network of bridges based on their current and future structural conditions. The method identifies typical bridges representing a group of railway bridges. The most crucial agents will be determined and categorized to criticality and vulnerability factors. Classification based on structural configuration, loading, and critical deterioration factors will be conducted. Finally a rating method for a network of railway bridges that takes into account the effects of damaged structural components due to variations in loading and environmental conditions on the integrity of the whole structure will be proposed. The outcome of this research is expected to significantly improve the rating methods for railway bridges by considering the unique characteristics of different factors and incorporating the correlation between them.

Synthetic rating system for railway bridge management

Railway bridges deteriorate with age. Factors such as environmental effects on different materials of a bridge, variation of loads, fatigue, etc. will reduce the remaining life of bridges. Dealing with thousands of bridges and several factors that cause deterioration, makes the rating process extremely complicated. Current simplified but practical methods of rating a network of bridges are not based on an accurate structural condition assessment system. On the other hand, the sophisticated but more accurate methods are only used for a single bridge or particular types of bridges. It is therefore necessary to develop a practical and accurate system, which will be capable of rating a network of railway bridges. This article introduces a new method to rate a network of bridges based on their current and future structural conditions. The method identifies typical bridges representing a group of railway bridges. The most crucial agents will be determined and categorized to criticality and vulnerability factors. Classification based on structural configuration, loading, and critical deterioration factors will be conducted. Finally a rating method for a network of railway bridges that takes into account the effects of damaged structural components due to variations in loading and environmental conditions on the integrity of the whole structure will be proposed. The outcome of this article is expected to significantly improve the rating methods for railway bridges by considering the unique characteristics of different factors and incorporating the correlation among them.

Wolbachia infection alters olfactory-cued locomotion in Drosophila spp

Wolbachia pipientis is an endosymbiotic bacterium present in diverse insect species. Although it is well studied for its dramatic effects on host reproductive biology, little is known about its effects on other aspects of host biology, despite its presence in a wide array of host tissues. This study examined the effects of three Wolbachia strains on two different Drosophila species, using a laboratory performance assay for insect locomotion in response to olfactory cues. The results demonstrate that Wolbachia infection can have significant effects on host responsiveness that vary with respect to the Wolbachia strain-host species combination. The wRi strain, native to Drosophila simulans, increases the basal activity level of the host insect as well as its responsiveness to food cues. In contrast, the wMel strain and the virulent wMelPop strain, native to Drosophila melanogaster, cause slight decreases in responsiveness to food cues but do not alter basal activity levels in the host. Surprisingly, the virulent wMelPop strain has very little impact on host responsiveness in D. simulans. This novel strain-host relationship was artificially created previously by transinfection. These findings have implications for understanding the evolution and spread of Wolbachia infections in wild populations and for Wolbachia-based vector-borne disease control strategies currently being developed.

Pixel value to electron density conversion for a Megavoltage Cone Beam CT System

Introduction: The motivation for developing megavoltage (and kilovoltage) cone beam CT (MV CBCT) capabilities in the radiotherapy treatment room was primarily based on the need to improve patient set-up accuracy. There has recently been an interest in using the cone beam CT data for treatment planning. Accurate treatment planning, however, requires knowledge of the electron density of the tissues receiving radiation in order to calculate dose distributions. This is obtained from CT, utilising a conversion between CT number and electron density of various tissues. The use of MV CBCT has particular advantages compared to treatment planning with kilovoltage CT in the presence of high atomic number materials and requires the conversion of pixel values from the image sets to electron density. Therefore, a study was undertaken to characterise the pixel value to electron density relationship for the Siemens MV CBCT system, MVision, and determine the effect, if any, of differing the number of monitor units used for acquisition. If a significant difference with number of monitor units was seen then pixel value to ED conversions may be required for each of the clinical settings. The calibration of the MV CT images for electron density offers the possibility for a daily recalculation of the dose distribution and the introduction of new adaptive radiotherapy treatment strategies. Methods: A Gammex Electron Density CT Phantom was imaged with the MVCB CT system. The pixel value for each of the sixteen inserts, which ranged from 0.292 to 1.707 relative electron density to the background solid water, was determined by taking the mean value from within a region of interest centred on the insert, over 5 slices within the centre of the phantom. These results were averaged and plotted against the relative electron densities of each insert with a linear least squares fit was preformed. This procedure was performed for images acquired with 5, 8, 15 and 60 monitor units. Results: The linear relationship between MVCT pixel value and ED was demonstrated for all monitor unit settings and over a range of electron densities. The number of monitor units utilised was found to have no significant impact on this relationship. Discussion: It was found that the number of MU utilised does not significantly alter the pixel value obtained for different ED materials. However, to ensure the most accurate and reproducible MV to ED calibration, one MU setting should be chosen and used routinely. To ensure accuracy for the clinical situation this MU setting should correspond to that which is used clinically. If more than one MU setting is used clinically then an average of the CT values acquired with different numbers of MU could be utilized without loss in accuracy. Conclusions: No significant differences have been shown between the pixel value to ED conversion for the Siemens MV CT cone beam unit with change in monitor units. Thus as single conversion curve could be utilised for MV CT treatment planning. To fully utilise MV CT imaging for radiotherapy treatment planning further work will be undertaken to ensure all corrections have been made and dose calculations verified. These dose calculations may be either for treatment planning purposes or for reconstructing the delivered dose distribution from transit dosimetry measurements made using electronic portal imaging devices. This will potentially allow the cumulative dose distribution to be determined through the patient’s multi-fraction treatment and adaptive treatment strategies developed to optimize the tumour response.