Adherence and experimental infection of bacteria associated with periodontal infections of young cattle in Brazil ("Cara inchada")

In vitro- and in vivo-assays were conducted, to study the possible role of streptomycin- and actinomycin-producing soil actinomycetes for the pathogenesis of "Cara inchada" in cattle (CI). Adherence of Bacteroides spp. to epithelial cells of the bovine gingiva, known to be associated with the progressive lesions of CI, was significantly increased by the addition of streptomycin, actinomycin or antibiotic culture supernatants of the soil actinomycetes. Applications of these mixtures together with Actinomyces pyogenes to the marginal gingiva of the upper premolar teeth of about 1 month old Holstein Friesian calves did not lead to progressive lesions of CI. Only one calf exhibited a slight diarrhea and a temporary retraction of the gingiva at the site of application.

Accidental and experimental salinomycin poisoning in rabbits

An outbreak of salinomycin poisoning in rabbits is described. At least 27 out of 2,000 rabbits reared on a farm died after the coccidiostatic drug sulfaquinoxaline was substituted by salinomycin in the feed. An average of 26.9ppm salinomycin was detected in the ration given to the rabbits. Clinical signs included anorexia, apathy and bradykinesia, which progressed to incoordination and recumbency. Gross lesions consisted of pale areas in the skeletal muscles. The histopathological findings showed severe necrotic degenerative myopathy in association with infiltration of neutrophils and macrophages. One rabbit exhibited similar alterations in the myocardium. Mineralization was observed in the affected skeletal muscles in some cases. In order to verify if the poisoning was due to salinomycin, 20 rabbits were divided into five groups and a ration containing the drug at doses of 10, 25, 50, 75 and 100ppm was given. The administration of doses higher than 50ppm resulted in manifestation of the clinical signs seen in the outbreak of poisoning. It was concluded, that probably an error related to the mixture of salinomycin in the feed was the cause of deaths in the spontaneous outbreak of poisoning on the rabbit farm.

Accidental and experimental Closantel intoxication in Uruguayan sheep

Abstract An outbreak of Closantel intoxication in sheep in Uruguay is described. The outbreak occurred in a group of 1300 weaning lambs treated orally with a 10% solution of Closantel. One hundred forty eight lambs showed clinical signs of intoxication and 14 died. The clinical signs included mydriasis, nystagmus, and negative pupillary reflex, bilateral blindness, bump into objects, and lateral movement of the head. No macroscopic lesions were observed. The histological lesions of the retina were cytoplasmic vacuolization in ganglion cells and in cells of the inner and outer nuclear layers with different degrees of atrophy. Vacuolization and axonal degeneration were observed in the optic nerve, with multifocal areas of fibrosis and infiltration by lymphocytes and Gitter cells. To reproduce the intoxication, four sheep were given two, four and 10 times the therapeutic dose of Closantel (0.1g/kg of BW). Only the animals receiving 10 times the recommended dose showed clinical signs. The histological examination of the lesions in experimental sheep showed similar results to those described in the accidental outbreak, except for the absence of optic nerve fibrosis and inflammation, characterizing an acute phase. Axonal myelin sheaths loss, fibroblasts and collagen fibers were observed in the ultrastructural study of the optic nerve of accidental intoxicated animals. The optic nerve of experimentally intoxicated animals had vacuoles that separated the myelin sheaths of axons. To prevent outbreaks it is suggested to weigh the animals before Closantel administration to avoid errors in dose calculation.

Numerical and experimental investigation of thermal louvers for space applications

Thermal louvers, using movable or rotating shutters over a radiating surface, have gained a wide acceptance as highly efficient devices for controlling the temperature of a spacecraft. This paper presents a detailed analysis of the performance of a rectangular thermal louver with movable blades. The radiative capacity of the louver, determined by its effective emittance, is calculated for different values of the blades opening angle. Experimental results obtained with a prototype of a spacecraft thermal louver show good agreement with the theoretical values.

A Temporal Analysis of Emotions in Girls' Secondary School Physical Education Games and Fitness Classes

Female enthusiasm towards engaging in physical education (PE) significantly decreases with age as it provides females with positive and negative emotional experiences. This study examined emotions within four grade nine female PE soccer and fitness classes (N = 67). Emotional patterns were studied over time and across two units of instruction and in relation to student grades. A mixed-method approach was utilized assessing the state emotions of shame, enjoyment, anxiety, and social physique anxiety (SPA). Results revealed unsatisfactory internal consistency for shame and thus it was removed. Statistical analysis revealed no significant changes in emotions over time, whereas qualitative analysis found that state emotions were inconsistent. Statistical analysis indicated that students in the fitness classes reported significantly higher levels of anxiety and SPA on the final class (p < .01). Qualitative analysis signaled different origins and themes of students‟ emotions. No predictive relationship between emotion and students‟ grade was found.

Towards reverse engineering of Photosystem II: Synergistic Computational and Experimental Approaches

ABSTRACT Photosystem II (PSII) of oxygenic photosynthesis has the unique ability to photochemically oxidize water, extracting electrons from water to result in the evolution of oxygen gas while depositing these electrons to the rest of the photosynthetic machinery which in turn reduces CO2 to carbohydrate molecules acting as fuel for the cell. Unfortunately, native PSII is unstable and not suitable to be used in industrial applications. Consequently, there is a need to reverse-engineer the water oxidation photochemical reactions of PSII using solution-stable proteins. But what does it take to reverse-engineer PSII’s reactions? PSII has the pigment with the highest oxidation potential in nature known as P680. The high oxidation of P680 is in fact the driving force for water oxidation. P680 is made up of a chlorophyll a dimer embedded inside the relatively hydrophobic transmembrane environment of PSII. In this thesis, the electrostatic factors contributing to the high oxidation potential of P680 are described. PSII oxidizes water in a specialized metal cluster known as the Oxygen Evolving Complex (OEC). The pathways that water can take to enter the relatively hydrophobic region of PSII are described as well. A previous attempt to reverse engineer PSII’s reactions using the protein scaffold of E. coli’s Bacterioferritin (BFR) existed. The oxidation potential of the pigment used for the BFR ‘reaction centre’ was measured and the protein effects calculated in a similar fashion to how P680 potentials were calculated in PSII. The BFR-RC’s pigment oxidation potential was found to be 0.57 V, too low to oxidize water or tyrosine like PSII. We suggest that the observed tyrosine oxidation in BRF-RC could be driven by the ZnCe6 di-cation. In order to increase the efficiency of iii tyrosine oxidation, and ultimately oxidize water, the first potential of ZnCe6 would have to attain a value in excess of 0.8 V. The results were used to develop a second generation of BFR-RC using a high oxidation pigment. The hypervalent phosphorous porphyrin forms a radical pair that can be observed using Transient Electron Paramagnetic Resonance (TR-EPR). Finally, the results from this thesis are discussed in light of the development of solar fuel producing systems.

Calmodulin/KCa3.1 channel interactions as determinant to the KCa3.1 Ca2+ dependent gating : theoretical and experimental analyses

Differentes études ont montré que la sensibilité au Ca2+ du canal KCa3.1, un canal potassique indépendant du voltage, était conférée par la protéine calmoduline (CaM) liée de façon constitutive au canal. Cette liaison impliquerait la région C-lobe de la CaM et un domaine de $\ikca$ directement relié au segment transmembranaire S6 du canal. La CaM pourrait égalment se lier au canal de façon Ca2+ dépendante via une interaction entre un domaine de KCa3.1 du C-terminal (CaMBD2) et la région N-lobe de la CaM. Une étude fut entreprise afin de déterminer la nature des résidus responsables de la liaison entre le domaine CaMBD2 de KCa3.1 et la région N-lobe de la CaM et leur rôle dans le processus d'ouverture du canal par le Ca2+. Une structure 3D du complexe KCa3.1/CaM a d'abord été générée par modélisation par homologie avec le logiciel MODELLER en utilisant comme référence la structure cristalline du complexe SK2.2/CaM (PDB: 1G4Y). Le modèle ainsi obtenu de KCa3.1 plus CaM prévoit que le segment L361-S372 dans KCa3.1 devrait être responsable de la liaison dépendante du Ca2+ du canal avec la région N-lobe de la CaM via les résidus L361 et Q364 de KCa3.1 et E45, E47 et D50 de la CaM. Pour tester ce modèle, les résidus dans le segment L361-S372 ont été mutés en Cys et l'action du MTSET+ (chargé positivement) et MTSACE (neutre) a été mesurée sur l'activité du canal. Des enregistrements en patch clamp en configuration ``inside-out`` ont montré que la liaison du réactif chargé MTSET+ au le mutant Q364C entraîne une forte augmentation du courant, un effet non observé avec le MTSACE. De plus les mutations E45A et E47A dans la CaM, ont empêché l'augmentation du courant initié par MTSET+ sur le mutant Q364C. Une analyse en canal unitaire a confirmé que la liaison MTSET+ à Q364C cause une augmentation de la probabilité d'ouverture de KCa3.1 par une déstabilisation de l'état fermé du canal. Nous concluons que nos résultats sont compatibles avec la formation de liaisons ioniques entre les complexes chargés positivement Cys-MTSET+ à la position 364 de KCa3.1 et les résidus chargés négativement E45 et E47 dans la CaM. Ces données confirment qu'une stabilisation électrostatique des interactions CaM/KCa3.1 peut conduire à une augmentation de la probabilité d'ouverture du canal en conditions de concentrations saturantes de Ca2+.

A theoretical and experimental dissociation of two models of decision‐making

La prise de décision est un processus computationnel fondamental dans de nombreux aspects du comportement animal. Le modèle le plus souvent rencontré dans les études portant sur la prise de décision est appelé modèle de diffusion. Depuis longtemps, il explique une grande variété de données comportementales et neurophysiologiques dans ce domaine. Cependant, un autre modèle, le modèle d’urgence, explique tout aussi bien ces mêmes données et ce de façon parcimonieuse et davantage encrée sur la théorie. Dans ce travail, nous aborderons tout d’abord les origines et le développement du modèle de diffusion et nous verrons comment il a été établi en tant que cadre de travail pour l’interprétation de la plupart des données expérimentales liées à la prise de décision. Ce faisant, nous relèveront ses points forts afin de le comparer ensuite de manière objective et rigoureuse à des modèles alternatifs. Nous réexaminerons un nombre d’assomptions implicites et explicites faites par ce modèle et nous mettrons alors l’accent sur certains de ses défauts. Cette analyse servira de cadre à notre introduction et notre discussion du modèle d’urgence. Enfin, nous présenterons une expérience dont la méthodologie permet de dissocier les deux modèles, et dont les résultats illustrent les limites empiriques et théoriques du modèle de diffusion et démontrent en revanche clairement la validité du modèle d'urgence. Nous terminerons en discutant l'apport potentiel du modèle d'urgence pour l'étude de certaines pathologies cérébrales, en mettant l'accent sur de nouvelles perspectives de recherche.

Theoretical and experimental study of intracavity laser absorption spectroscopy

In this thesis, a dual mode tunable gas sensor based on intracavity laser absorption spectroscopy (ICLAS) principle is investigated, both, numerically and experimentally. In order to minimize the cost and size of the gas sensor, relative intensity noise (RIN) is implemented as a detection parameter. Investigation is performed to determine the effect of injection current, operating temperature, mode spacing, and cavity length on RIN. It has been found that it is best to operate the gas sensor at smaller mode spacing and near the threshold current or at larger mode spacing and far above the threshold current for the use of RIN as the readout parameter.

Pharmaceutical innovation, reference pricing and therapeutic classes

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