O objetivo deste estudo foi comparar, in vitro, os sistemas de implante cone Morse, frente ao vedamento contra a penetração bacteriana entre o implante e o componente protético, em função de alterações estruturais e uso de selantes industriais. Foram utilizados 126 implantes Titamax CM EX distribuídos em três tipos de componentes protéticos: Munhão Universal CM, Munhão Universal CM com Parafuso Passante e Munhão Universal CM Exact, todos da empresa Neodent (Curitiba, Paraná, Brasil). Estes implantes foram divididos em 3 grupos de 42 implantes componentes protéticos, sendo os grupos devidamente denominados: Grupo 1 (G1) - Controle, Grupo 2 (G2) - Jateamento e Grupo 3 (G3) - Adesivo. Estes implantes, devidamente distribuídos entre os componentes protéticos e seus grupos, foram avaliados quanto à contaminação bacteriana em um período de 28 dias após o término da experimentação inicial em que foi realizado o efeito de ciclagem sobre as amostras (sem e com carga). Os implantes foram perfurados em sua porção apical com uma fresa de 1mm de diâmetro, até o encontro de sua câmara interna. Foram instalados os componentes protéticos de titânio em cada grupo com torque recomendado pelo fabricante (32 e 15 N.cm). Antes os componentes dos grupos G2 e G3 passaram por alterações estruturais (jateamento e adesivo Dermabond® respectivamente). As peças foram anexadas a tampas de tubo de ensaio, com a porção do componente voltada para o interior do tubo. Os tubos de ensaio foram preenchidos com meio de cultura líquido LB, utilizando-se seringa estéril. Todos os conjuntos receberam esterilização por radiação Gama (Embrarad, Campinas, Brasil). Após a confirmação da efetividade da esterilização por meio de amostras controle, os orifícios apicais foram cuidadosamente desobstruídos e inoculados com cultura de E. coli. O controle de turvamento das amostras foi realizado diariamente, os resultados apontaram que três das amostras do G1, sete do G2 e duas do G3, que não foram submetidas a ciclagem, sofreram contaminação num período de até 28 dias, e que três amostras do G1, dez do G2 e nenhuma do G3, quando submetidas ao efeito da ciclagem, foram contaminaram. Todos os grupos apresentaram infiltração bacteriana, independentemente do componente protético e da ciclagem. Ficou evidenciado que o grupo jateamento apresentou os piores resultados e que o adesivo apenas reduziu, mas não impediu a infiltração bacteriana para o interior dos implantes cone Morse. / The aim of this study was to compare, in vitro, Morse taper implant systems sealing against bacterial penetration between implant and prosthetic component after modifying the abutment structure or using industrial strength sealants. 126 Titamax CM EX implants and three different types of prosthetic components were used: Universal Post CM, CM Universal Post with passing screw and Universal Post CM Exact (Neodent implants, Curitiba, Parana, Brazil). These samples were divided into three groups: Group 1 Control group (G1); Group 2 Sandblasting (G2); and Group 3 Adhesive (G3). The implant / prosthetic component bacterial leakage from each group was evaluated after 28 days with or without cyclic loading. A hole at the apical portion of the implant was done with a 1 mm bur to access the implant internal threads. The abutments were inserted and torqued according to the manufacturer recommendation (15 or 32 N.cm). G2 abutments were sandblasted before insertion. G3 abutments were sealed with Dermabond® adhesive. The samples were sterilized by Gamma irradiation (Embrarad, Campinas, Brazil) and attached to the test tube lid and placed in the test tube filled with bacterial growth media (LB). Control samples from each group were used to assess bacterial contamination before starting the experiment. The access holes at the apical part of the implants were accessed and an E. coli culture was inoculated inside the implant internal threads and then sealed again. Changes in the media color (turbidity), indicative of bacterial leakage from inside the implant to the media were evaluated daily. Three samples from G1, seven from G2 and two from G3 without cyclic loading showed bacterial leakage after 28 days. Three samples from G1, ten from G2 and none of the samples from G3 showed bacterial leakage in the cyclic loading condition. All groups demonstrated bacterial leakage disregard of the type of abutment and loading conditions. It was demonstrated that G2 (sandblasted surface) had the worst results. Use of industrial sealant reduced but did not completely prevented bacterial leakage in Morse taper implants.

Este trabalho apresenta os parâmetros de transporte e atenuação dos íons \'K POT.+\', \'CU POT.2+\' e \'CL POT.-\' obtidos em ensaios de coluna, para uma mistura compactada e saturada de solos lateríticos da Formação Botucatu e Serra Geral. As soluções contaminantes percoladas foram cloretos de potássio e de cobre em três diferentes concentrações. Os resultados obtidos estão apresentados na forma de curva de chegada e os parâmetros de transporte e atenuação foram estimados através do ajuste de curvas teóricas aos dados experimentais das colunas. A mistura compactada mostrou-se satisfatória para o uso em barreiras selantes (liner) uma vez que os resultados de condutividade hidráulica e de sorção dos íons estudados são razoáveis. / This paper presents transport and attenuation parameters of \'K POT.+\', \'CU POT.2+\' e \'CL POT.-\', obtained in columns test using a compacted and saturated mixture of two lateritic soils from Botucatu and Serra Geral formation. The contaminant leaching solution was composed of KCl and \'CU\'CL IND.2\'.2\'H IND.2\'O\' with concentrations three different. The results obtained are presented in the form of breakthrough curves and the transport and attenuation parameters estimated through fitting procedures of the theorical curves related to the real column data. The compacted mixture showed to be satisfactory for liner usage since the results of the hydraulic conductivity and the ions sorption in these soils are reasonable.

Purpose: Determine the timeframe of bacterial penetration that occurs to the apex when obturation material (gutta percha) is exposed to bacteria for a set period of time (45 days) and to determine if bacterial penetration of the obturated root is influenced by the type of irrigant used during the final rinse (17% EDTA vs 2% Chlorhexidine vs full strength 5.25% NaOCl). Methods: Thirty-six extracted teeth, including six controls, were instrumented and irrigated with 5.25% NaOCl followed by a final rinse of either: 17% EDTA, 2% Chlorhexidine, or 5.25% NaOCl, and then obturated. Each root was suspended between two chambers: the coronal chamber inoculated with brain heart infusion broth and 〖10〗^8 colony-forming units of Enterococcus faecalis, the apical chamber with brain heart infusion broth. The latter was checked daily for turbidity, indicating bacterial leakage. Results: After excluding teeth with clear indications of experimental failure, 21 teeth were included in the analysis. Leakage rates were not significantly difference across the three groups (Chlorhexidine: 14%, EDTA: 67%, NaOCl: 50%; p-value=0.1581). Time to leakage was not significantly difference across the three groups (p-value=0.2470). Conclusion: Within the limitations of this study it was shown that leakage occurs between 4-42 days and that there was no significant difference between the different solutions in preventing leakage.

Background: Blood-borne infections are common problem in healthcare. Informations about the prevalence in dental care are limitet. Healthcare professionals in South Africa are particularly vulnerable to blood-borne infections. The best way to minimize blood-borne infections is to increase compliance to infection control. Objective: To describe and compare compliance to infection control routines and knowledge of blood-borne infections among  different groups of dental students at a university in Ga-Rankuwa, South Africa. Materials and method: A quantitative cross-section web-based survey. The participants were dental students who were registered in 2019, dental hygienist, dental therapist students, 3ed year and dental students 4th year. Non Parametric – Chi - Square and Fisher's test was used to analyze data. Result: Majority of the students had  compliance regarding the use of gloves and mask during patient treatment, changing gloves and disinfection of  unit between patients. Compliance was less at other parts where approximately half (49%) had the correct answer concerning: gloves, using of  gloves, clinical uniform and using of mobile and accessories. Correct answers to the knowledge of blood-borne infections för all dental students was 67%. Conclusions: The participants had better results on knowledge of blood-borne infections than on compliance to infection kontrol. No significant difference was found among the student dental groups

A series of physical and chemical analyses were conducted over a fifteen month period to establish the ecological risk, if any, of discharging minewater into aquatic ecosystems. Organic and inorganic analyses were used to determine the extent of contamination of minewater with soluble hydraulic fluids and other contaminant species. Throughout the sampling period the pithead discharge water exhibited a neutral pH and low levels of iron, manganese, zinc and potassium were found. Parallel toxicological and chemical studies identified elevated zinc levels above published toxicity levels for the test species Ceriodaphnia Dubia, but were not confirmed by subsequent study. The presence of organic species in the pit head discharge water was also identified, but the levels were found to be quite variable. Treatment processes involving the detention of the surface minewater and subsequent passage through wetlands exhibited a beneficial effect in reducing pollutant levels prior to disposal. Comparisons of the chemical composition of the minewater discharge with those of local waters were carried out and found to be similar in nature. / Master of Science (Hons)

Extended shelf-life cook-chill meals can pose a potential risk of botulism if they are subjected to a temperature abuse. Spores of group II non-proteolytic Clostridium botulinum can survive the mild heat treatment typically given to these products and can grow at refrigeration temperatures. To circumvent this safety issue, existing preservation methods can either affect the sensory properties of these foods or damage their image. Therefore, additional natural preservation hurdles are needed. Thus, the aim of this study was to develop a novel bio-preservation method based on the principle of antibiosis between protective cultures (PCs) and C. botulinum. Consequently, the objectives were to select effective anti-botulinal cultures and study their inhibition pattern in microbiological media and foods, identify the conditions for effective inhibition and the nature of the antibiosis. This research demonstrates for the first time that the bacteriocinogenic protective cultures inoculated at high levels had an anti-botulinal effect in a range of commercial cook-chill products, which supported active growth of non-proteolytic C. botulinum. The protocol for commercial application of the protective cultures was developed. / Doctor of Philosophy (PhD)

La pollution des sols par l'Arsenic (As) est une préoccupation environnementale grandissante dans plusieurs pays du monde : États-Unis, Canada, Mexique, Chine, Vietnam et France. L'émergence des techniques écologiques dites " phytoremédiation " constitue à l'heure actuelle une des solutions aux problématiques de décontamination des sols pollués par l'As. Aussi, elle permet de rallier le respect de l'état écologique des sites d'une part et le coût financier de traitement d'autre part. Pour cela, l'appréhension des interactions entre le végétal et l'As à l'interface racine-sol est nécessaire afin d'accélerer la mise en place de la phytoremédiation et de tester son efficacité. D'où l'objectif général de ce travail est d'étudier l'effet de quatres espèces végétales Holcus lanatus, Dittrichia viscosa, Lotus corniculatus et Plantago lanceolata sur la mobilité de l'As dans un sol à contamination géochimique en As (2000 mg kg-1). Notre étude a permis au départ de comparer et de caractériser la tolérance et la capacité accumulatrice des espèces séléctionnées à l'égard de l'As en milieu de culture et en sol contaminé chimiquement par l'As. Ensuite, l'étude de la mobilisation de l'As dans la rhizosphère a été réalisée par deux approches d'étude complémentaires : l'approche " rhizopot-rhizons " et l'approche " tapis racinaire ". L'approche " rhizopot-rhizons " nous a permis d'identifier d'intéressantes corrélations entre l'As et les paramètres suivis (NO3-, SO42- , Ca, Mg, P, pH, COD) tout au long de la période de croissance. Nous avons identifié et caractérisé plusieurs processus ifluençant la mobilisation de l'As dans la rhizosphère (alcalinisation/acidification, compétition anionique...). L'avantage de l'approche " rhizopot-rhizons " réside dans le fait que les plantes se sont développées sans prétraitement du substrat de croissance (contamination artificielle, ajout de solutions nutritives...). Par ailleurs, l'approche " tapis racinaire " a permis d'identifier quelques anions organiques dans les racines de P. lanceolata et de mettre en évidence le rôle du Phosphore dans la mobilisation de l'As dans la rhizosphère. Elle permet d'amplifier l'effet du système racinaire sur la mobilité de l'As dans le sol d'une part, et de récupérer entièrement le système racinaire tout en limitant les artefacts liés à la contamination des racines par le sol d'autre part.

L'huître creuse Crassostrea gigas est le produit aquacole le plus commercialisé dans le monde. Cependant, en France et dans d'autres régions du monde, des mortalités estivales massives affectent de façon alarmante les populations naturelles et cultivées de cette espèce, surtout aux stades juvéniles. Ces évènements sembleraient être liés à un déséquilibre entre les acteurs de la triade hôte - agent pathogène - environnement, favorisant l'affaiblissement des mécanismes de défense de l'hôte, et par conséquent, l'apparition et/ou l'augmentation de maladies. Parmi les facteurs environnementaux pouvant contribuer à ce déséquilibre, les contaminants chimiques sont connus pour moduler les capacités de défense de divers organismes aquatiques. Les phénoloxydases (PO) sont les enzymes-clés d'une cascade biochimique responsable de la production de mélanine et sont impliquées dans les défenses immunitaires et dans la reconnaissance du non-soi chez les invertébrés. Récemment, une activité de type PO a été détectée chez C. gigas, et a été proposée comme biomarqueur potentiel de la contamination chimique. Cependant, de nombreuses inconnues existent quant aux différents types d'activité PO présents chez C. gigas, et à leur implication dans les mécanismes de défense chez cette espèce. Dans ce contexte général,les objectifs de cette thèse ont été d' 1) identifier les différents types de PO présents dans différents tissus de l'huître 2)évaluer le potentiel des PO en tant que biomarqueurs dans des expériences d'exposition in vivo à des contaminants organiques, 3) évaluer le potentiel des PO en tant que biomarqueurs dans des études de biosurveillance in situ. Nous avons pu montrer, pour la première fois chez cette espèce, l'existence de deux types d'activité PO : une activité catécholase et une activité laccase. De plus, nous avons pu mettre en évidence in vitro un effet bactéricide lié à l'activité des PO contre deux souches pathogènes de l'huître, Vibrio splendidus et V. aesturianus, dont leur présence a été fréquemment associée aux phénomènes de mortalités estivales. Enfin, grâce à une analyse multi-biomarqueurs sur différents tissus de C. gigas,l'ensemble des résultats ont permis de proposer que les PO pourraient être utilisées comme biomarqueurs de stress environnemental, plutôt que de contamination, dans la surveillance de la qualité des eaux côtières et estuariennes.

<p>Because of the impact on human health and sustainable livelihood, the topic of drinking water and sanitation facilities is becoming a seriously discussed issue among international organizations as well as developing agencies in industrialized countries. The importance of water and sanitation management initialized this master thesis.</p><p> </p><p>The aim of the project is to do an assessment of the drinking water quality as well as the sanitation situation in the village Condrita in the Republic of Moldova. This was done by studying the existing water and sanitation facilities, sampling the water, evaluating the reason for the poor water quality and mapping the current situation using ArcGIS. Furthermore, technologies for improving the drinking water and sanitation facilities are suggested.</p><p> </p><p>The work was carried out by doing a literature study on how water sources and sanitation facilities should be constructed in order to ensure people’s health and to meet their needs. Geographic coordinates and water samples were collected from twenty-two public wells and springs. Interviews on the water situation and sanitation facilities were performed. Furthermore, water samples were analysed with respect to nitrate, turbidity, electrical conductivity and coliform bacteria amongst others. Pesticide contamination was also taken into consideration when one of the wells was analysed. Water sources were classified as improved or unimproved according to definitions by WHOSIS. Moreover, the DRASTIC vulnerability model was used to evaluate the groundwater susceptibility to contaminants.</p><p> </p><p>In general, the water quality in the study area was poor and measured values of the analyzed parameters exceeded international or Moldovan standards for nitrate, hardness, electrical conductivity and total coliform bacteria. Four wells were contaminated with <em>E. coli</em> bacteria. Furthermore, turbidity measurements exceeded Moldovan standards in seven out of twenty-two water sources. No pesticide contamination was detected. Sampled water from the densely populated parts of the village as well as unimproved water sources proved to be of poorer quality. Map results showed that a majority of the groundwater within the study area was subject to a moderate or high risk of becoming contaminated. The current sanitation situation is that most families use simple pit latrines, which are placed far away from the dwelling-houses. Digging a new toilet when the existing one is full is a common practice in Condrita. Hand-washing facilities are seldom placed in proximity to the toilets.</p><p> </p><p>Pit latrines are believed to be the most important source of groundwater contamination in the study area. Other sources are agricultural activities and poor practice when abstracting water from the wells. A feasible solution to improve both the drinking water quality and the sanitation situation would be to install ecosan toilets. Improvements of the well’s features that are suggested include construction of an apron slab as well as proper lids for covering the well.</p>

Graduation date: 1994