Facilitating Locking Pin Alignment in Transtibial Amputees via Auto-Retracting Tethered Pin

Thesis (Master's)--University of Washington, 2016-06

Dynamics of motor nerve terminal remodeling unveiled using SNARE-cleaving botulinum toxins: the extent and duration are dictated by the sites of SNAP-25 truncation

Nerve sprouts emerge from motor nerve terminals following blockade of exo-endocytosis for more than 3 days by botulinum neurotoxin (BoNT), and form functional synapses, albeit temporary. Upon restoration of synaptic activity to the parent terminal 7 and 90 days after exposure to BoNT/F or A respectively, a concomitant retraction of the outgrowths was observed. BoNT/E caused short-term neuroparalysis, and dramatically accelerated the recovery of BoNT/A-paralyzed muscle by further truncation of SNAP-25 and its replenishment with functional full-length SNARE. The removal of 9 C-terminal residues from SNAP-25 by BoNT/A leads to persistence of the inhibitory product due to the formation of a nonproductive SNARE complex(es) at release sites, whereas deletion of a further 17 amino acids permits replenishment and a speedy recovery. (C) 2003 Elsevier Science (USA). All rights reserved.

Repelling class discrimination: ephrin-A5 binds to and activates EphB2 receptor signaling

The interactions between Eph receptor tyrosine kinases and their ephrin ligands regulate cell migration and axon pathfinding. The EphA receptors are generally thought to become activated by ephrin-A ligands, whereas the EphB receptors interact with ephrin-B ligands. Here we show that two of the most widely studied of these molecules, EphB2 and ephrin-A5, which have never been described to interact with each other, do in fact bind one another with high affinity. Exposure of EphB2-expressing cells to ephrin-A5 leads to receptor clustering, autophosphorylation and initiation of downstream signaling. Ephrin-A5 induces EphB2-mediated growth cone collapse and neurite retraction in a model system. We further show, using X-ray crystallography, that the ephrin-A5-EphB2 complex is a heterodimer and is architecturally distinct from the tetrameric EphB2-ephrin-B2 structure. The structural data reveal the molecular basis for EphB2-ephrin-A5 signaling and provide a framework for understanding the complexities of functional interactions and crosstalk between A- and B-subclass Eph receptors and ephrins.

Characterization of a complex chemosensory signal transduction system which controls twitching motility in Pseudomonas aeruginosa

Virulence of the opportunistic pathogen Pseudomonas aeruginosa involves the coordinate expression of a wide range of virulence factors including type IV pili which are required for colonization of host tissues and are associated with a form of surface translocation termed twitching motility. Twitching motility in P. aeruginosa is controlled by a complex signal transduction pathway which shares many modules in common with chemosensory systems controlling flagella rotation in bacteria and which is composed, in part, of the previously described proteins PilG, PilH, PilI, PilJ and PilK. Here we describe another three components of this pathway: ChpA, ChpB and ChpC, as well as two downstream genes, ChpD and ChpE, which may also be involved. The central component of the pathway, ChpA, possesses nine potential sites of phosphorylation: six histidine-containing phosphotransfer (HPt) domains, two novel serine- and threonine-containing phosphotransfer (SPt, TPt) domains and a CheY-like receiver domain at its C-terminus, and as such represents one of the most complex signalling proteins yet described in nature. We show that the Chp chemosensory system controls twitching motility and type IV pili biogenesis through control of pili assembly and/or retraction as well as expression of the pilin subunit gene pilA. The Chp system is also required for full virulence in a mouse model of acute pneumonia.

Primary cilia in vertebrate corneal endothelial cells

The presence of primary cilia in corneal endothelial cells of a range of species from six non-mammalian vertebrate classes (Agnatha, Elasmobranchii, Amphibia, Teleostei, Reptilia, and Aves) is examined by scanning and transmission electron microscopy. Our aim is to assess whether these non-motile cilia protruding into the anterior chamber of the eye are a consistent phylogenetic feature of the corneal endothelium and if a quantitative comparison of their morphology is able to shed any new light on their function. The length (0.42-3.80 mum) and width (0.12-0.44 mum) of the primary cilia varied but were closely allied with previous studies in mammals. However, interspecific differences such as the presence of a terminal swelling in the Teleostei and Amphibia suggest there are functional differences. Approximately one-third of the endothelial cells possess cilia but the extent of protrusion above the cell surface varies greatly, supporting a dynamic process of retraction and elongation. The absence of primary cilia in primitive vertebrates (Agnatha and Elasmobranchii) that possess other mechanisms to control corneal hydration suggests an osmoregulatory and/or chemosensory function. (C) 2003 Elsevier Ltd. All rights reserved.

Estimating percolation and lateral water flow on sloping land in rainfed lowland rice ecosystem

Quantifying water losses in paddy fields assists estimation of water availability in rainfed lowland rice ecosystem. Little information is available on water balance in different toposequence positions of sloped rainfed lowland. Therefore, the aim of this work was to quantify percolation and the lateral water flow with special reference to the toposequential variation. Data used for the analysis was collected in Laos and northeast Thailand. Percolation and water tables were measured on a daily basis using a steel cylindrical tube with a lid and perforated PVC tubes, respectively. Percolation rate was determined using linear regression analysis of cumulative percolation. Assuming that the total amount of evaporation and transpiration was equivalent to potential evapotranspiration, the lateral water flow was estimated using the water balance equation. Separate perched water and groundwater tables were observed in paddy fields on coarse-textured soils. The percolation rate varied between 0 and 3 mm/day across locations, and the maximum water loss by lateral movement was more than 20 mm/day. Our results are in agreement with the previously reported findings, and the methodology of estimating water balance components appears reasonably acceptable. With regard to the toposequential variation, the higher the position in the topoesquence, the greater potential for water loss because of higher percolation and lateral flow rates.

Neural pathways mediating bilateral interactions between the upper limbs

The ease with which we perform tasks such as opening the lid of a jar, in which the two hands execute quite different actions, belies the fact that there is a strong tendency for the movements of the upper limbs to be drawn systematically towards one another. Mirror movements, involuntary contractions during intended unilateral engagement of the opposite limb, are considered pathological, as they occur in association with specific disorders of the CNS. Yet they are also observed frequently in normally developing children, and motor irradiation, an increase in the excitability of the (opposite) homologous motor pathways when unimanual movements are performed, is a robust feature of the mature motor system. The systematic nature of the interactions that occur between the upper limbs has also given rise to the expectation that functional improvements in the control of a paretic limb may occur when movements are performed in a bimanual context. In spite of the ubiquitous nature of these phenomena, there is remarkably little consensus concerning the neural basis of their mediation. In the present review, consideration is given to the putative roles of uncrossed corticofugal fibers, branched bilateral corticomotoroneuronal projections, and segmental networks. The potential for bilateral interactions to occur in various brain regions including the primary motor cortex, the supplementary motor area, non-primary motor areas, the basal ganglia, and the cerebellum is also explored. This information may provide principled bases upon which to evaluate and develop task and deficit-specific programs of movement rehabilitation and therapy. (c) 2005 Elsevier B.V. All rights reserved.

Degenerate dentition of the dugong (Dugong dugon), or why a grazer does not need teeth: morphology, occlusion and wear of mouthparts

The morphology and functional occlusion of the cheekteeth of 57 dugongs Dugong dugon of both sexes were examined using reflected light and scanning electron microscopy, radiography, hardness testing and skull manipulation. The functional morphology of the horny oral pads was also described. Mouthparts and body size allometry was examined for ontogenetic and gender-related trends. We found that the worn erupted cheekteeth of the dugong are simple flat pegs composed of soft degenerative dentine. During occlusion, the mandible moves in a mainly antero-lingual direction, with the possibility of mandibular retraction in some individuals. Anterior parts of the cheektooth row may become non-functional as a dugong ages. As a function of body size, dugong cheekteeth are extremely small compared with those of other mammalian herbivores, and with other hindgut fermenters in particular. The morphology, small size and occlusal variability of the cheekteeth suggest that there has not been strong selective pressure acting to maintain an effective dentition. In contrast, great development of the horny pads and associated skull parameters and their lower size variability suggest that the horny pads may have assumed the major role in food comminution.

Lasers - An effective artificial source of radiation for the cultivation of anoxygenic photosynthetic bacteria

The laser diode (LD) is a unique light source that can efficiently produce all radiant energy within the narrow wavelength range used most effectively by a photosynthetic microorganism. We have investigated the use of a single type of LID for the cultivation of the well-studied anoxygenic photosynthetic bacterium, Rhodobacter capsulatus (Rb. capsulatus). An array of vertical-cavity surface-emitting lasers (VCSELs) was driven with a current of 25 mA, and delivered radiation at 860 nm with 0.4 nm linewidth. The emitted light was found to be a suitable source of radiant energy for the cultivation of Rb. capsulatus. The dependence of growth rate on incident irradiance was quantified. Despite the unusual nearly monochromatic light source used in these experiments, no significant changes in the pigment composition and in the distribution of bacteriochlorophyll between LHII and LHI-RC were detected in bacterial cells transferred from incandescent light to laser light. We were also able to show that to achieve a given growth rate in a light-limited culture, the VCSEL required only 30% of the electricity needed by an incandescent bulb, which is of great significance for the potential use of laser-devices in biotechnological applications and photobioreactor construction. (c) 2006 Wiley Periodicals, Inc.

Spherical body formation in the spirochaete Brachyspira hyodysenteriae

When cultures of Brachyspira hyodysenteriae were grown under a wide range of in vitro conditions, at least 1% of the cells formed spherical bodies different to the normal helical form. This percentage increased considerably in aging cultures or following their incubation in caramelized media. Spherical body formation was initiated from a terminal localized swelling of the outer sheath followed by a retraction of the protoplasmic cylinder into the resulting swollen vesicle. As this occurred, the periplasmic flagella seemed to unwind from the protoplasmic cylinder. Once retracted, the protoplasmic cylinder was found to be wrapped in an organized manner around the inner surface of the membrane of the swollen vesicle. Although most were 2-3 mu m in diameter, some much larger spherical bodies (6-12 mu m diameter) were occasionally seen, with a corresponding increase in the visible number of peripheral protoplasmic cylinder cross-sections. Spherical bodies from older cultures did not contain protoplasmic cylinders arranged around the periphery, but instead were characterized by the presence of a centrally located, electron-dense body c. 0.5-0.8 mu m in diameter. Brachyspira hyodysenteriae spherical bodies differ in both their structural organization and probable method of formation from similar structures described in other spirochaete genera.

Swash-aquifer interaction in the vicinity of the water table exit point on a sandy beach

The coupling of sandy beach aquifers with the swash zone in the vicinity of the water table exit point is investigated through simultaneous measurements of the instantaneous shoreline (swash front) location, pore pressures and the water table exit point. The field observations reveal new insights into swash-aquifer coupling not previously gleaned from measurements of pore pressure only. In particular, for the case where the exit point is seaward of the observation point, the pore pressure response is correlated with the distance between the exit point and the shoreline in that when the distance is large the rate of pressure drop is fast and when the distance is small the rate decreases. The observations expose limitations in a simple model describing exit point dynamics which is based only on the force balance on a particle of water at the sand surface and neglects subsurface pressures. A new modified form of the model is shown to significantly improve the model-data comparison through a parameterization of the effects of capillarity into the aquifer storage coefficient. The model enables sufficiently accurate predictions of the exit point to determine when the swash uprush propagates over a saturated or a partially saturated sand surface, potentially an important factor in the morphological evolution of the beach face. Observations of the shoreward propagation of the swash-induced pore pressure waves ahead of the runup limit shows that the magnitude of the pressure fluctuation decays exponentially and that there is a linear increase in time lags, behavior similar to that of tidally induced water table waves. The location of the exit point and the intermittency of wave runup events is also shown to be significant in terms of the shore-normal energy distribution. Seaward of the mean exit point location, peak energies are small because of the saturated sand surface within the seepage face acting as a "rigid lid'' and limiting pressure fluctuations. Landward of the mean exit point the peak energies grow before decreasing landward of the maximum shoreline position.

The water balance on sloping land in rainfed lowland rice ecosystem

Quantifying water losses in paddy fields assists estimation of water availability in rainfed lowland rice ecosystem. There is, however, no definite method for determining the water losses, and little information is available on water balance in different toposequence positions of a sloped rainfed lowland. Therefore, the aim of this work was to quantify percolation and the lateral water flow with special reference to the toposequential variation. Data used for the analysis was collected in Laos and northeast Thailand. Percolation and water tables were measured on a daily basis. The percolator is a steel cylindrical tube with a lid to prevent water loss from evapotranspiration. The water table meter is a short PVC tube for determination of perched water table and a long PVC tube for groundwater table, and the side is perforated with 5-mm diameter holes at 20-mm distance. Percolation rate was determined using linear regression analysis of cumulative percolation. Assuming that the total amount of evaporation and transpiration was equivalent to potential evapotranspiration, the lateral water flow was estimated using the water balance equation. Our results are in agreement with the previously reported findings, and the methodology of estimating water balance components appears reasonably acceptable. With regard to the toposequential variation, the higher position in the topoesquence, the greater potential of the water losses because of higher percolation and lateral flow rates.

AVALIAÇÃO DENTOESQUELÉTICA E TEGUMENTAR DA RETRAÇÃO ANTERIOR EM DUAS FASES

O objetivo do presente estudo consistiu em avaliar as alterações dentoesqueléticas e tegumentares promovidas pelo tratamento ortodôntico fixo com a retração anterior em duas fases, por meio de telerradiografias em norma lateral. Foram selecionados 14 pacientes com idade média de 14,6 anos que necessitavam de extrações dos quatro primeiros pré-molares, todos apresentando má oclusão de Classe I. A retração anterior foi realizada inicialmente pela retração dos caninos (previamente à colagem dos incisivos) e subsequentemente, pelos incisivos. Doze pacientes não utilizaram qualquer dispositivo para ancoragem e dois pacientes utilizaram como ancoragem o Arco Extra-Bucal (AEB) de uso noturno. Foram avaliadas as telerradiografias em norma lateral ao início, final da retração dos caninos e final de tratamento ortodôntico fixo. As telerradiografias foram escaneadas e mensuradas por meio do programa Radiocef® (RadiomemoryR- Belo Horizonte, Brasil). Os dados foram submetidos à Análise de Variância e teste de Tukey (p<0,05). Os resultados demonstraram poucas alterações esqueléticas, exceto por uma retrusão suave do ponto A e aumento do comprimento mandibular, da altura facial ântero-inferior e total e rotação suave anti-horária mandibular devido ao crescimento craniofacial. Após a retração dos caninos, houve uma inclinação para lingual e retrusão dos incisivos superiores e inferiores, que permaneceram estáveis para os incisivos superiores no período final de tratamento. Já os incisivos inferiores neste mesmo período, retruíram mais com uma inclinação semelhante àquela inicial. Além disso, não houve perda de ancoragem de forma estatisticamente significante. Estas alterações dentárias refletiram em retrusão dos lábios superior e inferior após a retração dos caninos, sendo que o lábio inferior continuou a retrair no período final de tratamento. Conclui-se que o tratamento com a retração em duas fases não representou perda de ancoragem estatisticamente significante, além de diminuir a convexidade facial.

INFLUÊNCIA DO LASER DE BAIXA INTENSIDADE NA VELOCIDADE DA MOVIMENTAÇÃO ORTODÔNTICA

Este estudo investigou os efeitos do laser de baixa intensidade na velocidade da movimentação ortodôntica de caninos submetidos à retração inicial. A amostra constou de 26 caninos superiores e inferiores, submetidos à retração inicial realizada com mola Niti, com força de 150g. Um dos caninos foi irradiado com laser de diodo, seguindo o protocolo de aplicação: 780nm/20mW/5Jcm2/0,2J por ponto/Et=2J, nos dias 0, 3 e 7 pós-ativação, sendo que o contralateral foi considerado placebo. A retração durou em média 4 meses, num total de 9 aplicações de laser. Os modelos de cada mês foram escaneados com scanner 3D (3Shape) e as imagens tridimensionais foram analisadas por meio do Software Geomagic Studio 5, para a mensuração da quantidade de movimentação dos caninos retraídos. Foi empregada a Análise de Variância a três critérios, seguida pelo teste de Tukey (p<0,05). Para verificação da integridade tecidual, foram efetuadas radiografias periapicais iniciais e finais dos caninos retraídos e dos molares, nas quais foram avaliados uma possível reabsorção na crista alveolar, por meio da distância da crista óssea alveolar até a junção cemento-esmalte e os níveis de reabsorção radicular, por meio do índice de Levander e Malmgreen, sendo este último avaliado somente nos caninos retraídos. Para isto, foi empregado o teste não paramétrico de Wilcoxon (p<0,05). Os resultados indicaram que houve um aumento estatisticamente significante na velocidade da movimentação dos caninos irradiados comparados ao seu contralateral, em todos os tempos avaliados, como também a preservação da integridade tecidual. Com isso, concluiu-se que o laser de diodo pode acelerar a movimentação ortodôntica, podendo contribuir para a diminuição do tempo de tratamento.(AU)

A UTILIZAÇÃO DO LASER DE BAIXA INTENSIDADE NA MOVIMENTAÇÃO DENTÁRIA E NA SENSIBILIDADE DOLOROSA APÓS APLICAÇÃO DE FORÇA ORTODÔNTICA

O presente estudo objetivou avaliar a eficácia do Laser de Baixa Intensidade (LBI) na aceleração da movimentação dentária e na diminuição da dor frente à aplicação de força ortodôntica. A amostra foi composta por 19 pacientes, sendo doze do sexo feminino e sete do sexo masculino, com idade inicial média de 14,69 anos, todos com indicação para extrações de primeiros pré-molares. Destes, 66 caninos foram submetidos à retração inicial, sendo que 33 receberam aplicação de laser e 33 foram considerados controle. Utilizou-se o Laser de Baixa Intensidade de arseneto de gálio e alumínio, com comprimento de onda de 780nm, na dosimetria de 40mW;10J/cm2;10s/ponto, aplicado apenas uma vez ao mês em dez pontos, sendo cinco por vestibular e cinco por lingual/palatino. Modelos de gesso foram confeccionados durante todos os meses de retração dos caninos, que teve duração de quatro meses, sendo, posteriormente, digitalizados para se mensurar a quantidade de movimentação de um lado em relação ao outro, utilizando-se como referência as papilas incisivas. Para a avaliação da dor experimentada pelos pacientes, os mesmos foram orientados a preencher uma escala analógica visual (VAS) que variava de 0 a 10 , em que zero significava nenhuma dor e dez significava dor insuportável, nos intervalos de 12, 24, 48 e 72 horas após a aplicação da força ortodôntica. Foi mensurado o apinhamento de todas as hemiarcadas dos pacientes na fase inicial, medindo-se a distância entre os pontos de contato de cada dente. Para a verificação do padrão de normalidade, empregou-se o teste de Kolmogorov-Smirnov, sendo que para comparar o lado irradiado com o lado não irradiado foi utilizado o teste t pareado, exceto para a variável razão caninos/molares , analisada pelo teste não paramétrico de Wilcoxon (p<0,05). Os resultados mostraram que em relação ao apinhamento dentário, os lados irradiado e não irradiado apresentaram-se compatíveis. Além disso, não houve diferença estatisticamente significante entre a quantidade de retração dos caninos irradiados comparados aos não irradiados, o mesmo acontecendo com a sensibilidade dolorosa experimentada pelos pacientes. Concluiu-se assim que o LBI na dosimetria e forma como foi utilizado não foi eficiente na aceleração da movimentação dentária nem na redução da dor experimentada pelos pacientes frente às forças ortodônticas.