A proton nuclear magnetic resonance spectrum of the brain in vivo contains peaks from every proton-containing molecule in the brain. Sensitivity limitations mean that only those molecules present at concentrations of at least a few millimolar are detectable in a reasonable period of time; this still leaves many important molecules such as amino acids and other small metabolites. Most of their resonance frequencies fall in the region between 1.0 and 4.5 p.p.m. A typical linewidth in vivo is about 0.05 p.p.m., so the number of distinct peaks observable is restricted. The use of two-dimensional NMR techniques such as COSY can spread peaks out into a second dimension enabling otherwise overlapping peaks to be resolved. This thesis describes the development, testing and application of two such 2D NMR pulse sequences, dubbed ISIS-COSY and ISIS-JRES. They are based on an existing magnetisation localisation sequence and excite detected magnetisation in a manner analogous to the high-resolution sequences COSY and 2D J-resolved spectroscopy. A method for quantifying the metabolites visible in an ISIS-COSY spectrum from their cross-peak intensities is described, and results presented from both control rat brains and those of animals treated with vigabatrin, an inhibitor of GABA-transaminase that has the effect of increasing brain γ-amino butyric acid (GABA) levels. Further applications mentioned are in the study of neutrophil-infiltrated rat brain and adaptation of the ISIS-COSY technique for human use.

Spontaneous and evoked potentials (EPs) were recorded with cross-cortical microelectrode arrays following partial occlusion of the MCA and ACA in urethane-anaesthetised rats. The control group received no occlusion, while the treatment group was injected with anti-stroke peptide Tat-NR2B9c 5min before ischemia. Spontaneous EEG power significantly decreased in the stroke-only group when compared to controls (p<0.001). A greater loss of EEG power was observed on anterior electrodes closer to the occluded area versus posterior contacts in stroke-only rats (p<0.05). The Tat-NR2B9c+stroke group lost significantly less power when compared to stroke-only animals (p<0.05). EP amplitude in the stroke-only group was significantly reduced following ischemia when compared to control and Tat-NR2B9c+stroke animals (p<0.001). Epileptiform discharges were observed in 8/10 untreated stroke rats and 3/5 stroke rats treated with Tat-NR2B9c. The characteristic features of spontaneous and evoked potentials validate this rat focal stroke model for in vivo testing of pharmacological agents.

Spontaneous and evoked potentials (EPs) were recorded with cross-cortical microelectrode arrays following partial occlusion of the MCA and ACA in urethane-anaesthetised rats. The control group received no occlusion, while the treatment group was injected with anti-stroke peptide Tat-NR2B9c 5min before ischemia. Spontaneous EEG power significantly decreased in the stroke-only group when compared to controls (p<0.001). A greater loss of EEG power was observed on anterior electrodes closer to the occluded area versus posterior contacts in stroke-only rats (p<0.05). The Tat-NR2B9c+stroke group lost significantly less power when compared to stroke-only animals (p<0.05). EP amplitude in the stroke-only group was significantly reduced following ischemia when compared to control and Tat-NR2B9c+stroke animals (p<0.001). Epileptiform discharges were observed in 8/10 untreated stroke rats and 3/5 stroke rats treated with Tat-NR2B9c. The characteristic features of spontaneous and evoked potentials validate this rat focal stroke model for in vivo testing of pharmacological agents.

This project initiated with the aim for improving the ultrahigh resolution optical coherence tomography (UHR-OCT) system performance by considering the limitations to the axial OCT resolution for in vivo imaging of human and animal retina. To this end, a computational model was developed to simulate the effect of wavelength-dependant water absorption on the detected spectral shape of the broad-bandwidth light source used in UHR-OCT at 1060nm wavelength region, which effectively determines the axial OCT resolution in the retina. For experimental verification of the computational model, a custom built light source with a re-shaped spectrum (Superlum Inc.) was interfaced to the state-of-the-art UHR-OCT system. About 30% improvement of the axial OCT resolution in the rat retina and ~12% improvement of the axial OCT resolution in the human retina was achieved compared to the case of the almost Gaussian shaped spectrum of the standard, commercially available SLD. Although water absorption in the 1060nm spectral region strongly affects the sample beam, selecting a suitable light source with specific spectral shape can compensate for the undesired water absorption effect and thus result in significantly improved axial resolution in in vivo OCT retinal images. To demonstrate the advantages of the state-of-the-art OCT technology for non invasive retinal imaging, an established animal model of outer retina degeneration (sodium iodate (NaIO3)-induced retina degeneration) was employed for longitudinal monitoring of the degeneration and investigation of possible early and dynamic signs of damage undetected by other imaging modalities. The long-term (up to 3 months) and short-term (up to 12 hours) effect of sodium iodate toxicity on the layered structure of retina was monitored longitudinally and in vivo for the first time using OCT. An initial acute swelling of the retina, followed by progressive disruption and degeneration of outer retina was observed as a result of sodium iodate-induced damage. Changes in the thickness and optical reflectivity of individual retinal layers were extracted from the OCT images to quantify the changes occurring at different stages of the disease model. Results from this project present the theoretical and practical limits to the highest axial OCT resolution achievable for retina imaging in the 1060nm spectral range both in small animals and humans, and provided a framework for future development of novel light sources. Furthermore, UHR-OCT imaging was shown to be an effective and valuable modality for in vivo, non invasive investigation of retina degenerative disease.

Esta investigación se enmarca en una de las principales líneas que en la actualidad movilizan las reflexiones en la didáctica de las ciencias: la influencia del uso de modelos en el desarrollo del conocimiento científico de los estudiantes. En particular, el proceso de construcción y revisión del modelo ser vivo por niños y niñas de segundo curso del primer ciclo en una escuela pública de Barcelona durante la realización de una secuencia didáctica sobre los microorganismos. El objetivo principal consistió en analizar cómo los distintos modos comunicativos y las actividades experimental, lectora y comparativa contribuyen a la construcción del modelo ser vivo por estos alumnos. La implementación en el aula de la unidad didáctica diseñada permitió la obtención de datos de la investigación. Los instrumentos de recogida de datos fueron: cuestionarios KPSI (inicial y final), producciones gráficas, escritas y orales. El análisis de los datos se hizo a partir del análisis del contenido de las producciones de los alumnos, lo que permitió identificar la contribución de cada modo comunicativo y de cada actividad a partir del desempeño alcanzado en la progresión de aprendizaje al construir el modelo ser vivo. Así mismo, desde el marco teórico de la multimodalidad fue posible reconocer la relación de cooperación o de especialización de los distintos modos comunicativos en este proceso. Los resultados analizados revelaron que cada modo comunicativo contribuyó de forma específica. La representación gráfica permitió al alumnado expresar el proceso de evolución gradual de las caries, los elementos que creían esenciales para este proceso, el tamaño y cantidad del bicho, su morfología (siendo la más frecuente la similar a un insecto o humanoide) y su ubicación. La representación textual y oral permitió al alumnado enunciar procesos de interacción entre el alimento, la caries y el ser vivo, así mismo a evidenciar la confusión entre los conceptos caries y bacteria. Analizando los tres modos comunicativos se observa que la relación más frecuente entre ellos es la especialización, en las representaciones individuales el dibujo alcanzó un mayor nivel de desempeño en la progresión de aprendizaje con relación a los demás modos comunicativos. Así mismo, la cooperación entre los modos comunicativos fue encontrada en otros casos, cuando las representaciones del alumnado se encontraban en el mismo nivel de desempeño. En las discusiones entre iguales, constatamos que a través del modo oral se alcanza un nivel mayor de desempeño, en tres de los cuatro grupos, caracterizando por tanto una relación de especialización con el dibujo y el texto y mostrando el potencial del discurso oral en la construcción de conocimiento. A través del análisis del contenido de los elementos argumentativos generados en la discusión entre iguales, se observó que el alumnado dio mucha importancia a aspectos formales del dibujo, siendo el color el más representativo. Los aspectos más fundamentales del modelo se produjeron una vez decididos los aspectos formales. La influencia de las tres actividades propuestas fue diversa. El planteamiento de la actividad experimental – elaboración del yogur – fue demasiado ambicioso y los alumnos no fueron capaces de reconocer la importancia del medio en la vida de las bacterias, aunque si permitió discutir el efecto de la temperatura. La actividad lectora permitió reconocer de manera explícita la relación entre consumo de dulces, reproducción y crecimiento de las bacterias y desarrollo de las caries. Así mismo, la actividad comparativa de la bacteria con otro ser vivo (conejo) permitió a los estudiantes generalizar el modelo ser vivo construido en el curso anterior, aplicándolo a un organismo microscópico. Esta actividad permitió al alumnado progresar en su nivel de desempeño al reconocer la presencia de células en ambos seres vivos. Analizar el proceso de construcción del modelo ser vivo a través de la identificación de niveles de desempeño en la progresión de aprendizaje facilita el reconocimiento de dificultades y puede orientar en el diseño de las secuencias de aprendizaje implementadas en el aula. / This research falls within one of the main lines that currently move the reflections on science education: the influence of the use of models in the development of scientific knowledge of the students. In particular, in the process of construction and revision of the living being model by children in the second year of primary education in a public school in Barcelona during the performance of a learning sequence on microorganisms. The main objective was to analyze to what extent the different communicative modes and experimental, reading and comparative activities contribute to the construction of the living being model of these students. The implementation of the designed learning sequence allowed obtaining research data. Data was collected using KPSI questionnaires (collected at the beginning and at the end of the sequence), drawings of the students as well as their written and oral productions. Data analysis consisted in content analysis of the worksheets of the students, which allowed to identify the contribution of each communicative mode as well as the contribution of each activity from the performance achieved in the learning progression in the construction of the living being model. Likewise, the theoretical framework of multimodality was used to analyze and recognize the relationship between the different communicative modes in this process, which could be cooperation or specialization. The results revealed that each communicative mode contributed in a specific way to the construction of the living being model. The graphic representation (drawings) allowed students to express the gradual process of evolution of dental caries process as well as the components they believed essential to this process: size and quantity of the bug, its morphology (most frequently being similar to an insect or humanoid) and its location. Oral and textual representations allowed students to spell out the processes of interaction between food, dental caries and a living being, it also allowed to highlight the conceptual confusion between dental caries and bacteria. By analyzing the three communicative modes it is observed that the most common relation between them is the specialization: in the individual representations the drawing reached a higher level of performance in learning progression than the other communicative modes. Furthermore, the relation of cooperation between communicative modes was found in other cases, where representations of students reached the same level of performance. In peer discussion activities, it can be noted that through the oral mode a higher level of performance is reached in three of the four groups, therefore characterizing a relationship of specialization between drawing and text, and showing the potential of oral discourse in the construction of knowledge. Through the content analysis of the argumentative elements generated during the peer discussion, it was noted that students gave great importance to formal aspects of the drawing, the color being the more representative. The most fundamental aspects of the model ocurred once the formal features were set. The influence to the construction of the living being model of the three proposed activities was different. The approach of the experimental activity - preparation of yogurt - was too ambitious and the students were not able to recognize the importance of the environment in the life of the bacteria, but it allowed to discuss the effect of temperature. The reading activity allowed to recognize explicitly the relationship between consumption of candies, reproduction and growth of bacteria and the development of dental caries. Furthermore, the comparative activity between bacteria and another living being (a rabbit) allowed students to generalize the living being model (which they had worked in the previous year), applying it to a microscopic organism. This activity allowed the students to progress in their level of performance to recognize the presence of cells in both living beings. Analyzing the process of construction of the living being model by the identification of levels of performance in a learning progression, facilitates the recognition of difficulties and can guide the design of learning sequences to be implemented in the classroom.

Introduction Bacterial biofilms have been implicated in the pathogenesis of Chronic Rhinosinusitis (CRS). This thesis consists of a number of separate studies. The results of each study were designed to help provide an evolution of knowledge that could be applied to our subsequent investigations on the topic of bacterial biofilms and chronic rhinosinusitis. In vitro studies were utilized to document the capacity of CRS bacteria to form biofilms as well as to investigate the efficacy of various antimicrobials at high concentrations. Additionally, an in vivo sheep model was developed to examine different biofilm detection techniques. Finally, a study of CRS patients was conducted to investigate the incidence of biofilm related sinus disease. Methods Our in vitro studies used 96 well crystal violet microtiter plate assays to determine the biofilm growth characteristics of S.aureus isolated from patients with CRS. Established biofilms were then subjected various antimicrobial agents, and the degree of biofilm reduction calculated to examine their potential for sinus biofilm treatment. A sheep sinusitis model involved performing endoscopic sinus surgery, occlusion of frontal sinus ostia and the introduction of bacteria. Mucosal specimens were subsequently examined for the presence of bacterial biofilms using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). CSLM was also used in a prospective study to document the presence bacterial biofilms on the mucosa of patients with CRS compared to controls. Results The findings of in vitro experiments revealed that not all isolates were capable of forming biofilms. Of the antibiotics tested, only Mupirocin was capable of reducing biofilm mass by 90% in all isolates. The animal model showed considerable variation in biofilm detection rates. The CSLM biofilm detection rate was 100% in obstructed sinuses with bacteria introduced, whereas TEM detected only 66%. Both these objective measures failed to identify biofilms in control groups. SEM found biofilms in all experimental groups including controls. CSLM analysis of CRS patients found Bacterial biofilms in 44% and no biofilms in controls. Conclusion The demonstration of biofilms in the sheep model for sinusitis and biofilms on the mucosal specimens of patients with CRS, and the ability of bacteria in CRS to form biofilms in vitro, further supports the hypothesis that biofilms play a role in the pathogenesis of CRS. CSLM is the modality of choice in documenting the presence of bacterial biofilms on sinus mucosal surfaces due to the inherent flaws of sampling error and subjectivity of TEM and SEM. Finally, CRS is a multi-factorial disease, topical Mupirocin via nasal irrigation may be a therapeutic option in patients with likely S.aureus biofilms. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1367183 / Thesis (M.S.) - University of Adelaide, School of Medicine, 2009

Introduction Bacterial biofilms have been implicated in the pathogenesis of Chronic Rhinosinusitis (CRS). This thesis consists of a number of separate studies. The results of each study were designed to help provide an evolution of knowledge that could be applied to our subsequent investigations on the topic of bacterial biofilms and chronic rhinosinusitis. In vitro studies were utilized to document the capacity of CRS bacteria to form biofilms as well as to investigate the efficacy of various antimicrobials at high concentrations. Additionally, an in vivo sheep model was developed to examine different biofilm detection techniques. Finally, a study of CRS patients was conducted to investigate the incidence of biofilm related sinus disease. Methods Our in vitro studies used 96 well crystal violet microtiter plate assays to determine the biofilm growth characteristics of S.aureus isolated from patients with CRS. Established biofilms were then subjected various antimicrobial agents, and the degree of biofilm reduction calculated to examine their potential for sinus biofilm treatment. A sheep sinusitis model involved performing endoscopic sinus surgery, occlusion of frontal sinus ostia and the introduction of bacteria. Mucosal specimens were subsequently examined for the presence of bacterial biofilms using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). CSLM was also used in a prospective study to document the presence bacterial biofilms on the mucosa of patients with CRS compared to controls. Results The findings of in vitro experiments revealed that not all isolates were capable of forming biofilms. Of the antibiotics tested, only Mupirocin was capable of reducing biofilm mass by 90% in all isolates. The animal model showed considerable variation in biofilm detection rates. The CSLM biofilm detection rate was 100% in obstructed sinuses with bacteria introduced, whereas TEM detected only 66%. Both these objective measures failed to identify biofilms in control groups. SEM found biofilms in all experimental groups including controls. CSLM analysis of CRS patients found Bacterial biofilms in 44% and no biofilms in controls. Conclusion The demonstration of biofilms in the sheep model for sinusitis and biofilms on the mucosal specimens of patients with CRS, and the ability of bacteria in CRS to form biofilms in vitro, further supports the hypothesis that biofilms play a role in the pathogenesis of CRS. CSLM is the modality of choice in documenting the presence of bacterial biofilms on sinus mucosal surfaces due to the inherent flaws of sampling error and subjectivity of TEM and SEM. Finally, CRS is a multi-factorial disease, topical Mupirocin via nasal irrigation may be a therapeutic option in patients with likely S.aureus biofilms. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1367183 / Thesis (M.S.) - University of Adelaide, School of Medicine, 2009

Introduction Bacterial biofilms have been implicated in the pathogenesis of Chronic Rhinosinusitis (CRS). This thesis consists of a number of separate studies. The results of each study were designed to help provide an evolution of knowledge that could be applied to our subsequent investigations on the topic of bacterial biofilms and chronic rhinosinusitis. In vitro studies were utilized to document the capacity of CRS bacteria to form biofilms as well as to investigate the efficacy of various antimicrobials at high concentrations. Additionally, an in vivo sheep model was developed to examine different biofilm detection techniques. Finally, a study of CRS patients was conducted to investigate the incidence of biofilm related sinus disease. Methods Our in vitro studies used 96 well crystal violet microtiter plate assays to determine the biofilm growth characteristics of S.aureus isolated from patients with CRS. Established biofilms were then subjected various antimicrobial agents, and the degree of biofilm reduction calculated to examine their potential for sinus biofilm treatment. A sheep sinusitis model involved performing endoscopic sinus surgery, occlusion of frontal sinus ostia and the introduction of bacteria. Mucosal specimens were subsequently examined for the presence of bacterial biofilms using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). CSLM was also used in a prospective study to document the presence bacterial biofilms on the mucosa of patients with CRS compared to controls. Results The findings of in vitro experiments revealed that not all isolates were capable of forming biofilms. Of the antibiotics tested, only Mupirocin was capable of reducing biofilm mass by 90% in all isolates. The animal model showed considerable variation in biofilm detection rates. The CSLM biofilm detection rate was 100% in obstructed sinuses with bacteria introduced, whereas TEM detected only 66%. Both these objective measures failed to identify biofilms in control groups. SEM found biofilms in all experimental groups including controls. CSLM analysis of CRS patients found Bacterial biofilms in 44% and no biofilms in controls. Conclusion The demonstration of biofilms in the sheep model for sinusitis and biofilms on the mucosal specimens of patients with CRS, and the ability of bacteria in CRS to form biofilms in vitro, further supports the hypothesis that biofilms play a role in the pathogenesis of CRS. CSLM is the modality of choice in documenting the presence of bacterial biofilms on sinus mucosal surfaces due to the inherent flaws of sampling error and subjectivity of TEM and SEM. Finally, CRS is a multi-factorial disease, topical Mupirocin via nasal irrigation may be a therapeutic option in patients with likely S.aureus biofilms. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1367183 / Thesis (M.S.) - University of Adelaide, School of Medicine, 2009

Tübingen, Univ., Diss., 2007.

Tübingen, Universiẗat, Diss., 2006.