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1
Haque, Sameena. "In Vivo Imaging of Corneal Conditions using Optical Coherence Tomography." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2976.
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Purposes: To use optical coherence tomography (OCT) to image and quantify the effect of various corneal conditions, in terms of corneal, stromal and epithelial thickness, and light backscatter. To assess the changes caused by overnight orthokeratology (Corneal Refractive Therapy; CRTTM) lens wear, keratoconus and laser in-situ keratomileusis (LASIK) refractive surgery, each of which may lead to topographical alterations in corneal thickness either by temporary moulding, degeneration, or permanent laser ablation, respectively. Methods: Topographical thickness of the cornea was measured using OCT in all studies. The CRTTM studies investigated myopic and hyperopic treatment, throughout the day. The myopic studies followed lens wear over a 4 week period, which was extended to 12 months, and investigated the thickness changes produced by two lenses of different oxygen transmissibility. CRTTM for hyperopia (CRTHTM) was evaluated after a single night of lens wear.
In the investigation of keratoconus, OCT corneal thickness values were compared to those obtained from Orbscan II (ORB) and ultrasound pachymetry (UP). A new fixation device was constructed to aid in the measurement of topographical corneal and epithelial thickness along 8 directions of gaze. Pachymetry maps were produced for the normal non-lens wearing cornea, and compared with the rigid gas permeable (RGP) lens wearing cornea and the keratoconic cornea.
Thickness changes prior to, and following LASIK were measured and monitored throughout six months. Myopic and hyperopic correction was investigated individually, as the laser ablation profiles differ for each type of procedure. The LASIK flap interface was also evaluated by using light backscatter data to monitor healing.
Results: Following immediate lens removal after myopic CRTTM, the central cornea swelled less than the periphery, with corneal swelling recovering to baseline levels within 3 hours. The central epithelium decreased and mid-peripheral epithelium increased in thickness, with a more gradual recovery throughout the day. There also seemed to be an adaptation effect on the cornea and epithelium, showing a reduced amount of change by the end of the 4 week study period. The thickness changes did not alter dramatically during the 12 month extended study. In comparing the two lens materials used for myopic CRTTM (Dk/t 91 vs. 47), there were differences in stromal swelling, but no differences in the central epithelial thinning caused by lens wear. There was a statistically insignificant asymmetry in mid-peripheral epithelial thickening between eyes, with the lens of lower Dk causing the greater amount of thickening. Hyperopic CRTTM produced a greater increase in central stromal and central epithelial thickness than the mid-periphery. Once again, the stroma recovered faster than the epithelium, which remained significantly thicker centrally for at least six hours following lens removal.
Global pachymetry measurements of the normal cornea and epithelium found the periphery to be thicker than the centre. The superior cornea and epithelium was thicker than the inferior. In the measurement of the keratoconic cornea, OCT and ORB correlated well in corneal thickness values. UP measured greater values of corneal thickness. The keratoconic epithelium was thinner than normal, and more so over the apex of the cone than at the centre. The location of the cone was most commonly found in the inferior temporal region. Central epithelial thickness was thinner in keratoconics than in RGP lens wearers, which in turn was thinner than in non-lens wearers.
Following LASIK surgery for both myopia and hyperopia, the topographical OCT thickness profiles showed stromal thinning in the areas of ablation. The central myopic cornea showed slight regression at 6 months. During early recovery, epithelial thickness increased centrally in hyperopes and mid-peripherally in myopes. By the end of the 6 month study, mid-peripheral epithelial thickness was greater than the centre in both groups of subjects. The light backscatter profiles after LASIK showed a greater increase in backscatter on the anterior side of the flap interface (nearer the epithelium), than the posterior side (in the mid-stroma) during healing. The flap interface was difficult to locate in the OCT images at 6 months.
Conclusion: All the CRTTM lenses used in this project produced more corneal swelling than that seen normally overnight without lens wear. In order for these lenses to be worn safely for long periods of time without affecting the health of the cornea, they need to be manufactured from the highest oxygen transmissible material available. The long-term effect of thinning on the epithelium's barrier properties needs to be monitored closely.
Global topographical thickness of the cornea and epithelium was measured using OCT in normal, RGP lens wearing and keratoconic eyes. Corneal and epithelial thickness was not symmetrical across meridians. The epithelium of RGP lens wearers was slightly thinner than normal, but not as thin as in keratoconics, suggesting that the epithelial change seen in keratoconus is mainly due to the condition.
Post-LASIK corneal and epithelial thickness profiles were not the same for myopic and hyperopic subjects, since the ablation patterns vary. Epithelial thickening in the mid-periphery had not recovered by six months in myopes or hyperopes, possibly indicating epithelial hyperplasia. Light backscatter profiles were used to monitor the recovery of the LASIK flap interface, showing the band of light backscatter around the flap interface to decrease as the cornea healed.
2
Persson, Eva. "Drug Dissolution under Physiologically Relevant Conditions In Vitro and In Vivo." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7195.
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Carruthers, Michael D. "Transcriptional analysis of Escherichia coli O157:H7 during in vivo mimicking conditions." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3389094.
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Wei, Hongjiang. "In vivo diffusion tensor imaging (DTI) for the human heart under free-breathing conditions." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0127/document.
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L'orientation des fibres myocardiaque est à la base du comportement électro-mécanique du cœur, et connue pour être altérée dans diverses maladies cardiaques telles que la cardiopathie ischémique et l'hypertrophie ventriculaire. Cette thèse porte principalement sur l'imagerie in vivo du tenseur de diffusion (diffusion tensor imaging—DTI) en vue d’obtenir la structure des fibres myocardiques du cœur humain dans des conditions de respiration libre. L'utilisation de DTI pour l'étude du cœur humain in vivo est un grand défi en raison du mouvement cardiaque. En particulier, l’acquisition DTI avec respiration libre sans recourir au gating respiratoire est très difficile à cause des mouvements à a fois respiratoire et cardiaque. Pour aborder ce problème, nous proposons de nouvelles approches consistant à combiner des acquisitions à retards de déclenchement multiples (trigger delay—TD) et des méthodes de post-traitement. D’abord, nous réalisons des acquisitions avec multiples TD décalés en fin de diastole. Ensuite, nous développons deux méthodes de post-traitement. La première méthode s’attaque au problème d’effets de mouvement physiologique sur DTI cardiaque in vivo en utilisant les techniques de recalage et de PCATMIP (Principal Components Analysis filtering and Temporal Maximum Intensity Projection). La deuxième méthode traite le problème de mouvement par l’utilisation d’un algorithme de fusion d’images basé sur l’ondelette (wavelet-based image fusion-WIF) et d’une technique de débruitage PCA (Principal Components Analysis). Enfin, une comparaison des mesures DTI entre la méthode PCATMIP et la méthode WIF est réalisée ; les champs de tenseurs sont calculés, à partir desquels les propriétés de l’architecture des fibres in vivo sont comparées. Les résultats montrent qu’en utilisant les approches proposées, il est possible d’étudier l’impact du mouvement cardiaque sur les paramètres de tenseur de diffusion, et d’explorer les relations sous-jacentes entre les propriétés de tenseur de diffusion mesurées et le mouvement cardiaque. Nous trouvons aussi que la combinaison des acqusiitions avec des TD multiples décalés and des post-traitements d’images peut compenser les effets de mouvement physiologique, ce qui permet d’obtenir l’architecture 3D du cœur humain dans des conditions de respiration libre. Les résultats suggèrent de nouvelles solutions au problème de perte du signal due au mouvement, qui sont prometteuses pour obtenir les propriétés de l’architecture des fibres myocardiques du cœur humain in vivo, dans des conditions cliniquesThe orientation of cardiac fibers underlies the electro-mechanical behavior of the heart, and it is known to be altered in various cardiac diseases such as ischemic heart disease and ventricular hypertrophy. This thesis mainly focuses on in vivo diffusion tensor imaging (DTI) to obtain the myocardial fiber structure of the human heart under free-breathing conditions. The use of DTI for studying the human heart in vivo is challenging due to cardiac motion. In particular, free-breathing DTI acquisition without resorting to respiratory gating is very difficult due to both respiratory and cardiac motion. To deal with this problem, we propose novel approaches that combine multiple shifted trigger delay (TD) acquisitions and post-processing methods. First, we perform multiple shifted TD acquisitions at end diastole. Then, we focus on two different post-processing methods. The first method addresses physiological motion effects on in vivo cardiac DTI using image co-registration and PCATMIP (Principal Components Analysis filtering and Temporal Maximum Intensity Projection). The second method is a wavelet-based image fusion (WIF) algorithm combined with a PCA noise removing method. Finally, a comparison of DTI measurements between the PCATMIP and WIF methods is also performed; tensor fields are calculated, from which the in vivo fiber architecture properties are compared. The results show that using the proposed approaches, we are able to study the cardiac motion effects on diffusion tensor parameters, and investigate the underlying relationship between the measured diffusion tensor properties and the cardiac motion. We also find that the combination of multiple shifted TD acquisitions and dedicated image post-processing can compensate for physiological motion effects, which allows us to obtain 3D fiber architectures of the human heart under free-breathing conditions. The findings suggest new solutions to signal loss problems associated with bulk motion, which are promising for obtaining in vivo human myocardial fiber architecture properties in clinical conditions
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Rovery, Clarisse. "Etude de la transcription de Rickettsia conorii dans différentes conditions in vitro et in vivo." Aix-Marseille 2, 2009. http://www.theses.fr/2009AIX20668.
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Rickettsia conorii, l’agent causal de la fièvre boutonneuse méditerranéenne, est transmis aux humains par la morsure de Rhipicephalus sanguineus. Le séquençage du génome de ces bactéries intracellulaires strictes a permis de mieux comprendre leur phylogénie et de développer des approches post-génomiques (transcriptomique, protéomique). Le but de cette thèse était de mieux comprendre la pathogénicité de ces microorganismes en étudiant le transcriptome de R. Conorii dans différentes conditions. Nous avons pu montrer en reproduisant in vitro des conditions de stress de la bactérie que la transcription des gènes spoT ainsi que l’expression de rOmpA, une protéine majeure de surface variaient en fonction de ces conditions. Nous avons pu ensuite valider une méthode d’analyse globale du transcriptome de R. Conorii en utilisant une ‘mini-puce à ADN’. L’utilisation d’une puce à ADN correspondant à la totalité du génome nous a permis pour la première fois d’étudier la transcription de l’ensemble des gènes de R. Conorii in vivo dans des escarres prélevées chez des patients présentant une fièvre boutonneuse méditerranéenne. Nos résultats ont montré que R. Conorii avait un profil transcriptionnel remarquablement conservé quels que soit les patients atteints, et quel que soit le génotype en cause. Etant donné que l’escarre est le site d’introduction des rickettsies, l’analyse du profil transcriptionnel observé dans cette étude illustre en partie la façon dont les rickettsies contre-attaquent le système de défense de l’hôte. Globalement, nous pensons que ces résultats contribuent à une meilleure connaissance des capacités d’adaptation et de la pathogénicité de R. Conorii.
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Mittag, Manuel [Verfasser]. "Functional in vivo calcium imaging in the hippocampus under healthy and disease conditions / Manuel Mittag." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1208937480/34.
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Pirot, Nelly. "Conséquences in vivo de l'absence de Lyl sur la fonction endothéliale en conditions physiologique et pathologique." Montpellier 2, 2009. http://www.theses.fr/2009MON20100.
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Le facteur de transcription bHLH LYL, apparenté à TAL-1, est exprimé dans les systèmes hématopoïétique et cardiovasculaire embryonnaires. La souris déficiente en Lyl (Lyl-/-) est viable mais présente un nombre réduit de lymphocytes B et une altération de l'autorenouvellement à long terme des cellules souches hématopoïétiques. Jusqu'à présent, rien n'était connu sur le rôle de LYL dans les cellules endothéliales. Les résultats présentés dans cette thèse montrent que Lyl est exprimé aussi bien dans l'endothélium angiogénique que quiescent. Son absence amplifie l'angiogenèse observée dans des tumeurs syngéniques ou dans des plugs de matrigel. Les vaisseaux tumoraux sanguins sont plus larges, plus perméants et plus immatures. Ce phénotype des néovaisseaux est associé à un maintien de l'expression de Tal-1 et une augmentation de l'expression d'Ang-2 et de la VE-cadhérine. In vitro, l'invalidation de LYL dans des HUVEC conduit à une diminution de l'expression de gènes impliqués dans la régulation des jonctions adhérentes et dans la liaison à la matrice extracellulaire. Ces données démontrent que Lyl joue un rôle dans l'initiation et le maintien de la stabilisation des vaisseaux sanguins. De plus, l'étude de la vasculature pulmonaire a montré la présence d'infiltrats inflammatoires dans les poumons des souris Lyl-/-, associés à une perméabilité accrue de l'endothélium. Lyl participerait donc également à la régulation de l'intégrité de la barrière vasculaire pulmonaire. Ce travail démontre pour la première fois l'importance de Lyl dans la cellule endothéliale et ouvre de nouvelles voies d'exploration sur la régulation de l'angiogenèse et le contrôle de la perméabilité vasculaireThe transcriptional factor LYL, belonging to the bHLH family, is expressed in developing hematopoietic and vascular systems. Lyl-deficient mice are viable and display a reduced number of mature B cells and a diminution in the frequency of immature progenitors. Up to now, nothing was known concerning the role of LYL in endothelial cell. The results presented in this thesis demonstrated that Lyl is expressed both in angiogenic and quiescent endothelium. In vivo, deletion of Lyl increases angiogenesis processes observed in syngenic tumors and in matrigel plugs subcutaneously implanted in mice. Tumor blood vessels from Lyl-deficient mice are larger, leakier and more immature. This phenotype of newly formed vessels is associated with a sustained expression of Tal-1 and an increased expression of Ang-2 and VE-cadherin. In vitro, LYL invalidation by siRNA in HUVEC induces the reduction of the expression of genes regulating the formation of adherens junctions and the binding to extracellular matrix. All together, these results demonstrate that Lyl is involved in the initiation and the maintenance of blood vessels stabilization and maturation. Furthermore, the study of the vascularized organs in adult mice showed the presence, in the lungs of Lyl-deficient mice, of cellular infiltrates composed of inflammatory cells and associated with an increased permeability of the endothelium. Therefore, Lyl might also be involved in the maintenance of endothelial barrier in the lung. This work establishes for the first time the importance of Lyl in the endothelial cell physiology and opens news ways to study the regulation of angiogenesis and the control of vascular permeability
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Rodriguez, Alejandro. "Studies of Stroma Formation and Regulation in Human Pathological Conditions and in Experimental in vivo Models." Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-120688.
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Fibrosis is a sequel of chronic inflammation and is defined as an excessive deposition of collagen that ultimately leads to organ dysfunction. To date there are no effective treatments for fibrosis. The main cell type involved in collagen deposition and organization is the myofibroblast. In the first study we examined how myofibroblasts differentiate in human fibrotic conditions and in experimental animal models. Human tissues were stained with antibodies that recognize integrin receptors and in addition we also stained for α-SMA, a myofibroblast marker. We found a co-localization between these two markers in stromal cells and hypothesized that integrin α1 is important for the acquisition of the myofibroblast phenotype. To tests this hypothesis we used knockout animals for this integrin subunit. These animals showed a reduction of α-SMA positive fibroblasts, indicating that the α1 integrin subunit is required for proper myofibroblast differentiation. In the second study we used a neuroblastoma tumor model to study tumour growth when a drug targeting the synthesis of cellular NAD was administered. In treated animals an expansion of the nonvascular stroma was observed compared to controls. Normalization of the vasculature was observed in treated tumors together with a decrease in hypoxia. Moreover, this was followed by a decrease in stromal PDGF-B and VEGF expression, suggesting a deactivation of the stroma. In the third study the effects of over-expression of the two pro-fibrotic growth factors TGF-β and PDGF-B in skin was evaluated. We observed that both growth factors induced fibrosis. Over time, a decrease in blood vessel density was observed in both treatment groups. Both factors also stimulated an expansion of the connective tissue cell population originating from the microvascular pericyte, but the phenotype of these cells differed in the different treatments with regards to expression of markers. Furthermore, in tissue over-expressing PDGF-B but not TGF-β, the fibrotic process was partially reversible.
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Hoon, QiCai Jason. "Fracture biomechanics of screw-hole defects under various loading conditions – An ex-vivo feline femoral model." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/26243.
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Objective: Feline cortical bone has anecdotally been described to be brittle, tending to fissure and shatter readily under load. Evidence for appropriate screw size selection in feline patients appears limited with current guidelines of 25-33% bone diameter being extrapolations from other species. The study aims to evaluate the biomechanical properties of feline femora with screw-hole defects of increasing diameter, subjected to three-point bending and torsion to failure at two different loading rates.
Study design: Eighty femoral pairs were harvested from adult cat cadavers. For each bending and torsional experiment, there were five groups (n=8 pairs) of increasing screw-hole defects (Intact, 1.5mm, 2.0mm, 2.4mm and 2.7mm). Mid-diaphyseal bicortical defects were created with an appropriate pilot drill-hole and tapped accordingly. Left and right femora of each pair were randomly assigned to a destructive loading protocol at low (10mm/min; 0.5˚/s) or high rates (3000mm/min; 90˚/s) respectively. Stiffness, load/torque-to-failure, energy-to-failure, and fracture morphology were recorded.
Results: No significant differences in stiffness and load/torque-to-failure were noted with increasing deficit sizes in all loading conditions. Screw-hole defects up to 33% bone diameter had a maximum of 20% reduction in bending and torsional strength compared to intact bone at both loading rates. Higher loading rates showed significantly increased stiffness and load/torque-to-failure in bending and torsion compared to low loading rates (p<0.001).
Conclusion: 2.7mm screw-hole defects did not significantly reduce feline bone failure properties in this ex vivo femoral study. These findings support current screw-size selection guidelines of up to 33% bone diameter as appropriate for use in feline fracture osteosynthesis.
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Hristovska, Ines. "Dynamique microgliale en conditions physiologiques : un mécanisme contrôlé par les états de vigilance et l’activité neuronale." Thesis, Lyon, 2019. https://n2t.net/ark:/47881/m60c4v3q.
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Les microglies, cellules immunitaires résidentes du système nerveux central (SNC), étaient traditionnellement décrites comme ayant un rôle uniquement lors de blessures ou de maladies du SNC. De manière frappante, dans le cerveau sain, les microglies effectuent une surveillance active du parenchyme en étendant et en rétractant leurs prolongements ramifiés. Ce mouvement est connu sous le nom de motilité microgliale et peut être dirigé vers les synapses. La régulation de ces mouvements et le but des contacts microglie-épines dendritiques restent inconnus. Nous avons examiné l'influence de l'activité neuronale sur la motilité et la morphologie microgliale ainsi que sur les interactions microglies-épines pendant l’éveil et le sommeil. Nous avons observé que les propriétés morpho-dynamiques des microglies sont modulées par les états de vigilance. Les prolongements microgliaux sont attirés par les synapses actives, particulièrement lors de l’éveil, alors que le sommeil régule négativement la proximité des prolongements microgliaux ainsi que les contacts dépendant de l’activité qui lient les prolongements microgliaux aux épines. Le contact des épines avec les prolongements microgliaux entraîne une augmentation de l’activité des épines, principalement observée pendant le sommeil lent. Pour conclure, ces résultats montrent un contrôle complexe de la morpho-dynamique microgliale par l’activité et les états de vigilance. Appréhender les mécanismes régulant la dynamique microgliale et les interactions microglie-épines dendritiques pendant les états de vigilance permettra de mieux comprendre comment les cellules microgliales sont impliquées dans la régulation de l'homéostasie synaptique, l'apprentissage et de la mémoire, des fonctions associées au sommeil. La compréhension des interactions microglies-neurones dans des conditions physiologiques est cruciale pour élucider le fonctionnement synaptique et ses altérations lorsque la microglie est impliquée dans ses fonctions immunes, une caractéristique commune à la plupart des pathologies cérébralesMicroglia, the resident immune cells of the central nervous system (CNS), were traditionally believed to be set into action only by injury or diseases. Strikingly, in the healthy brain, microglia actively carry out parenchyma patrolling by extending and retracting their ramified processes. These movements are referred to as microglial motility and may be to some extent directed toward synapses. However, motility regulation and the purpose of microglia-spine contacts remain elusive. We thus examined the influence of neuronal activity on microglial motility, morphology and microglia-spine interactions during sleep and wakefulness. We found that microglial motility and morphology are modulated by vigilance states. Microglial processes were found to be attracted by active synapses particularly during wake, whereas sleep downregulates microglial proximity and activity-dependent contact with spines. Microglial contact resulted in increased spine activity which was mainly observed during sleep. Understanding the mechanisms regulating microglial dynamics and microglia-spine interactions across the vigilance states will provide further insights into how microglial cells may be involved in sleep- associated functions such as synaptic homeostasis, learning and memory. Grasping these cellular interactions in physiological conditions is crucial to understand synaptic functioning and alterations when microglia are engaged into their immune functions, a hallmark of most brain pathologies
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Cozzolino, Olga. "Two-photon imaging with fluorescent biosensors to study neuronal activity in vivo in physiological and pathological conditions." Doctoral thesis, Scuola Normale Superiore, 2019. http://hdl.handle.net/11384/85930.
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The development of tools to allow in vivo measurement in intact neural
circuitry represents a dramatic improvement in our understanding of
brain activity. Understanding brain function is not only a challenging
scientific quest aiming to disentangle the functional relationship among
the electro-chemical dynamics in the brain with the cognitive and
behavioral outputs, but it’s also a clinically crucial endeavor toward the
study, diagnostics, treatment, and intervention of neurological diseases.
Since the advent of laser scanning microscope has allowed for biological
structures to be imaged at the theoretical limits of resolution predicted by
Abbe, in vivo imaging poses significant and unique optical challenges
beyond simply providing an enlarged view of a specimen. Two-photon
laser scanning fluorescent microscopy has become the imaging standard
for in vivo imaging due to its ability to obtain high signal-to-noise
dynamic images while inducing minimal damage to the sample of interest.
At the same time the development of fluorescent protein-based biosensors
has been crucial for life science research. The information obtained
through brain imaging facilitate both functional interpretation and
medical advancements toward addressing neurological diseases. While
this method provides unique merits in studying brain activities, it also
accompanies certain pitfalls that prevent the technique to dominate.
Complementary to optical neuroimaging is electrophysiology, through
which electric signals in the brain can be detected and related to neuronal
and cortical functions. Different approaches often requires appropriate data analysis to reveal the complexity of the mechanisms we are dealing
with.
Here I present the development of two techniques that allow to explore
different aspects of neuronal computation.
In Chapter 1, “Does High GABA always mean High Inhibition?” I
present a tool for in vivo measurement of intracellular chloride
concentration as a proxy for the understanding of inhibitory capability of
the neural circuits during development and during day cycles in mice. In Chapter 2, “Statistically-based approach: a new way to study epilepsy
in Zebrafish” I introduce a novel approach to exploit the complementarity
of calcium imaging and electrophysiology to better understand conditions
associated to hyperexcitability such as epilepsy.
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Schramm, Adrien. "Impact de conductances synaptiques et intrinsèques sur les propriétés de décharge de neurones corticaux in vivo en conditions artificielles et fonctionnelles." Paris 6, 2010. http://www.theses.fr/2010PA066092.
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Dans le système nerveux central, le neurone s'inscrit dans un réseau de neurones interconnectés. Chaque neurone va prendre en compte la multitude d'entrées synaptiques qu'il reçoit du réseau et décider ou non de renvoyer à son tour un message en fonction de ses propriétés propres. Dans cette thèse je me suis attaché à évaluer l'impact de deux conductances sur la décharge des neurones. La première est synaptique, il s'agit de l'inhibition shunante portée par les canaux GABAA et la deuxième est intrinsèque, elle est responsable du courant porté par les canaux BK. Pour répondre à cette question nous avons caractérisé, in vivo, la fonction de transfert Entrée/Sortie de neurones du cortex visuel et somato sensoriel de chats et de rats en réponse à des stimuli artificiels (saut de courant ou de conductance) et fonctionnels (stimulation visuelle). Le dynamic-clamp imposé en patch-clamp à l'aveugle en cellule entière nous a permit de simuler les conductances étudiées et de quantifier leur impact sur les fonctions de transferts neuronales. Nous avons pu montrer l'action à la fois linéaire et non linéaire de l'inhibition shuntante sans remplir les conditions présumées nécessaires dans les précédents travaux. De même, nous avons confirmé un rôle non intuitif de la conductance BK qui, bien que provoquant un courant hyperpolarisant, va agir en amplifiant la réponse neuronale. Pour répondre aux difficultés techniques de tels enregistrements, nous avons développé de nouvelles techniques, en particulier pour l'accès au milieu intracellulaire en patch clamp
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Toews, Judy. "Mass spectrometric indentification of formaldehyde-induced modifications of peptides and proteins under in vivo protein cross-linking conditions." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/921.
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Formaldehyde cross-linking has been used to study protein-protein interactions in cells. Its short spacer arm, ability to permeate through cell membrane and the reversibility of the cross-linking reaction makes this a desirable cross-linker for in vivo studies. Although it has been widely used as a cross-linking reagent, the detailed chemistry behind protein cross-linking is not well understood. In vitro studies conducted under extended incubation periods (2 days) have shown that a multitude of amino acids are reactive to formaldehyde and that residue accessibility appears to play a role in reactivity. How applicable these findings are to formaldehyde cross-linking studies done under in vivo conditions (10-20 min incubations) is unclear. The chemistry of formaldehyde cross-linking was therefore investigated in model peptides under conditions similar to those used in in vivo studies. It was observed that only a subset of amino acids (amino termini and side chains of lysine and tryptophan) that were found reactive under extended incubation times was reactive in the much shorter incubation period. No cross-linking was detected between peptides, and elevating the peptide and formaldehyde concentrations resulted in only a minimal amount of cross-linked peptides. The relationship between residue accessibility and formaldehyde reactivity was assessed in model proteins that contain a more complex tertiary structure. It was shown that the extent of formaldehyde reactivity was dependent on the state of protein unfolding, i.e., solvent accessibility of reactive residues, and that an unfolded protein showed a significantly higher number of formaldehyde-induced modifications than a folded form, with lysine being the predominant reactive site. Formaldehyde treatment of proteins in their native form resulted in a low number of modifications even under an increased incubation time, suggesting that the protein remains folded during the course of the reaction. This is important for in vivo cross-linking studies where specificity and stability of protein-protein interactions is dictated by protein tertiary structure.
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Duong, Sun. "Evaluation of novel fluorescent probes for in vivo Transthyretin amyloid using fibrils generated in vitro under varying conditions." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-154611.
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Transthyretin (TTR) amyloidosis is a disease that appears in three variants. One variant affects the elderly population with heart failure, the other two variants are hereditary and caused by an amino acid substitution in the gene, resulting in polyneuropathy and/or heart issues depending on the amino acid substitution. However, in all three variants, other organs may also be affected with amyloid deposition in the disease course. Amyloid fibrils of TTR (ATTR) contains a mixture of full-length protein and fragments (50-127). Luminescent conjugated oligothiophenes (LCO’s) are novel amyloid binding probes used to stain amyloid fibrils and these amyloid probes have the feature of characterizing the amyloid structure in terms of fluorescence spectra. Apart from LCO’s, a few other amyloid binding probes are used to stain recombinant amyloid transthyretin and native transthyretin for binding studies. The majority of generated TTR aggregates in vitro did not have the characteristic fluorescence spectra when bound to LCO’s and was observed as a clumped gel-like aggregate. The generation of recombinant TTR fibrils in vitro using the mutant TTR-T49M to obtain an aggregation prone fragment (50-127) after being treated with cyanogen bromide had a low yield of in vivo amyloid-like fibrils, but with characteristic LCO spectra. Carpal tunnel ATTR often precedes ATTR deposition in heart tissue. Amyloid transthyretin in carpal tunnel tissues was stained with LCO’s and used as a reference in the comparison against the in vitro generated recombinant amyloid transthyretin fibrils. This project also includes quantification of amyloid transthyretin in a few selected parts of the carpal tunnel tissue using ImageJ. In the long run this method could help in diagnosing TTR amyloidosis.
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Morizane, Asuka. "Optimal conditions for in vivo induction of dopaminergic neurons from embryonic stem cells through cell-derived inducing activity." Kyoto University, 2004. http://hdl.handle.net/2433/147450.
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BUFFOLO, FEDERICA. "In vitro and in vivo characterization of the RE-1 Silencing Transcription Factor (REST) activity under neuroinflammatory conditions." Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/939868.
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The ability to specifically target epigenetic and molecular mechanisms involved in neuronal development could be an alternative therapeutic strategy for neuroinflammatory/neurodegenerative disorders such as Multiple Sclerosis (MS). The transcriptional repressor RE1-Silencing Transcription Factor (REST) regulates neurogenesis and neuronal identity through cell-specific gene repression, allowing expression of its targets in mature neurons where REST is quiescent. REST dysregulation has been implicated in several neurodegenerative disorders, including Alzheimer and Huntington diseases, tumors of the nervous system, and epilepsy.
We found that REST is overexpressed in the spinal cord of mice with experimental autoimmune encephalomyelitis (EAE), suggesting that its dysregulation might be an important factor in the pathogenesis of the disease. Starting from these observations, we have firstly analyzed the expression of REST target genes in EAE and characterized the cell-specificity of REST overexpression, investigating the differential contribution of neuronal and glial cell populations to REST upregulation. Moreover, in order to mimic the inflammatory EAE scenario, we have analyzed REST activity in primary neuron cultures treated with various pro-inflammatory cytokines. Altogether, this study provides the basis for understanding the molecular mechanisms of REST expression during brain inflammation and its implication in the subsequent neurodegenerative processes.
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Smithpeter, Colin Lee. "Fiber optic confocal imaging for in vivo detection and diagnosis of pre-cancerous lesions /." Digital version accessible at:, 1997. http://wwwlib.umi.com/cr/utexas/main.
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Budidha, K. "In vivo investigations of photoplethysmograms and arterial oxygen saturation from the auditory canal in conditions of compromised peripheral perfusion." Thesis, City, University of London, 2016. http://openaccess.city.ac.uk/16134/.
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Pulse oximeters rely on the technique of photoplethysmography (PPG) to estimate arterial oxygen saturation (SpO2). In conditions of poor peripheral perfusion such as hypotension, hypothermia, and vasoconstriction, the PPG signals detected are often small and noisy, or in some cases unobtainable. Hence, pulse oximeters produce erroneous SpO2 readings in these circumstances. The problem arises as most commercial pulse oximeter probes are designed to be attached to peripheral sites such as the finger or toes, which are easily affected by vasoconstriction. In order to overcome this problem, the ear canal was investigated as an alternative site for measuring reliable SpO2 on the hypothesis that blood flow to this central site is preferentially preserved. Novel miniature ear canal PPG sensors were developed along with a state of the art PPG processing unit and a data acquisition system to allow for PPG measurements from different depths and surfaces of the ear canal. A preliminary in vivo investigation on seven healthy volunteers has revealed that good quality PPG signals with high amplitude can be obtained from the posterior surface of the outer ear canal. Based on these observations, a second prototype probe suitable for acquisition of PPGs from the posterior surface of the outer ear canal was developed. A pilot study was then carried out on 15 healthy volunteers to validate the feasibility of measuring PPGs and SpO2 from the ear canal in conditions of induced local peripheral vasoconstriction (right hand immersion in ice water). The PPG signals acquired from the ear canal probe were compared with those obtained simultaneously from finger probes attached to the left and the right index fingers. Significant drop (p< 0:05) in amplitude was observed in the PPG signals acquired from the left (> 45%) and right (> 50%) index fingers during the ice water immersion, while good quality PPG signals with relatively constant amplitude were obtained from the ear canal. Also, the SpO2 values showed that the ear canal pulse oximeter performed better than the two finger pulse oximeters (mean failure rate 30%). A second in vivo investigation was carried out in 15 healthy volunteers, where hypoperfusion was induced more naturally by exposing the volunteer to cold temperatures of 10C for 10min. Normalised Pulse Amplitude (NPA) and SpO2 was calculated from the PPG signals acquired from the ear canal, the finger and the earlobe. By the end of the cold exposure, a mean drop of > 80% was found in the NPA of finger PPGs. The % drop in the NPA of red and infrared earlobe PPG signals was 20% and 26% respectively. Contrarily to both these sites, the NPA of the ear canal PPGs had only dropped by 0.2% and 13% respectively. The SpO2 estimated from the finger sensor was below 90% in 5 volunteers (failure) by the end of the cold exposure. The earlobe pulse oximeter failed in 3 volunteers. The ear canal sensor on the other hand had only failed in 1 volunteer. These results strongly suggest that the ear canal may be used as a suitable alternative site for reliable monitoring of PPGs and SpO2 in cases of compromised peripheral perfusion.
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Carletti, Renzo. "Characteristics of NMDA receptor ligands in rodent brain, in vivo and in vitro, under normal conditions and after chronic ischaemia." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243989.
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Karray, Sahar. "Etude écotoxicologique et phylogéographique de la coque Cerastoderma glaucum issue du Golfe de Gabès : réponse adaptative (in situ et in vivo) au stress métallique et structure génétique." Thesis, Le Mans, 2015. http://www.theses.fr/2015LEMA1007/document.
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Cerastoderma glaucum est un modèle biologique de choix pour des études phylogéographiques et écotoxicologiques.Une étude de sa structure génétique en méditerranée occidentale a été réalisée en utilisant deux types de marqueurs, mitochondrial et nucléaire. Les résultats obtenus ont révélé à travers l’ADN mitochondrial une population très divergente de toutes les autres populations (Ellouza, Sud de la Tunisie).Une étude écotoxicologique sur des populations issues de ce site Ellouza et deux autres sites à proximité dans la région du golfe de Gabès a été réalisée dans le but d’étudier la réponse adaptative des populations de la coque C. glaucum en milieu naturel à différents niveaux de l’organisation biologique allant du niveau individuel jusqu’au niveau cellulaire et moléculaire. En parallèle à cette étude, deux expérimentations en laboratoire ont été réalisées afin de préciser les mécanismes pouvant expliquer le succès ou l’échec du maintien des populations de C. glaucum. La première expérimentation a été réalisée en utilisant des effluents industriels et la deuxième en utilisant un contaminant pur le cadmium. Les niveaux de l’organisationbiologique concernés par cette étude étaient le niveau individuel et le niveau moléculaire. Différents biomarqueurs impliqués dans la réponse à différents types de stress : (MT), (ABCB1), (MnSOD et CuZnSOD), (CAT), (HSP70) et (COI) ont été utilisés en milieu naturel ainsi qu’en conditions contrôlées et les résultats obtenus ont montré l’importance dumétabolisme énergétique dans la réponse au stress quelque soit l’approche utilisée (in situ/ expérimental) à travers la régulation de l’expression du gène COICerastoderma glaucum is an adequate biological model for phylogeographic and ecotoxicological studies.A study of its genetic structure in the Western Mediterranean sea was conducted using two markers types: mitochondrial and nuclear. The DNA mitochondrial marker results show a divergent population from all the other ones (Ellouza South ofTunisia).An ecotoxicological study of populations sampled from Ellouza site and two other nearby sites in the Gulf of Gabes region was carried out in order to study the adaptive response of natural populations of C. glaucum at different levels of biological organization from the individual level to the cellular and molecular ones. In parallel, two laboratory experiments were performed to clarify the mechanisms that may explain the success or failure of maintaining populations of C. glaucum. In thefirst one, industrial effluents were used and in the second we have used a pure contaminant, the cadmium. These studies experiments concerned individual and molecular levels. Different biomarkers involved in the response to different types of stress: (MT), (ABCB1) (MnSOD and CuZnSOD) (CAT) (HSP70) and (COI) were used in natural and exposed cockles.Results showed the importance of energy metabolism in response to stress whatever the used approach (in situ / Experimental) through the regulation of the expression of the COI gene
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Pagès-Hélary, Sandy. "Libération en bouche des molécules de la flaveur : influence des composés salivaires au niveau macroscopique et moléculaire." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS055/document.
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L’objectif de cette étude est d’étudier le rôle de la salive dans la libération des molécules odorantes, par deux approches, in vitro et in vivo. L’effet des protéines salivaires sur la libération de 10 molécules odorantes (5 esters et 5 cétones, de longueur de chaîne hydrophobe variable) a été étudié in vitro dans des systèmes modèles composés de salives artificielles et humaine. Les salives artificielles contiennent les protéines majoritairement présentes dans la salive (mucine et alpha-amylase), seules et en mélange. Les quantités de chaque molécule odorante présentes dans la phase gazeuse à l’équilibre thermodynamique ont été mesurées par une analyse headspace en mode statique couplée à la chromatographie en phase gazeuse (SH-GC). Les coefficients de partage entre l’air et chacun des systèmes modèles ont été calculés pour chacune des molécules. Cette approche in vitro nous a permis de démontrer une diminution des coefficients de partage air/salive artificielle en présence de mucine et d’alpha-amylase, par un effet hydrophobe. Aucun effet cumulatif n’est observé lorsque les deux protéines sont mises ensemble en solution. En présence de salive humaine, une diminution des coefficients de partage est également observée, les esters étant plus affectés par la présence de salive humaine que les cétones. Cette observation est due à une activité des estérases de la salive, qui augmente avec l’hydrophobicité des esters. La libération in vivo du propanoate d’éthyle et de l’hexanoate d’éthyle a été suivie sur 10 sujets par spectrométrie de masse à ionisation chimique à pression atmosphérique (APCI-MS) dans des conditions physiologiques différentes : au repos, après stimulation et après élimination du film salivaire résiduel. La salive de chaque sujet a été caractérisée dans les différentes conditions physiologiques testées. De grandes variations de flux, viscosité et de composition salivaire ont été mises en évidence entre les sujets, ainsi qu’entre les conditions physiologiques pour un même sujet. Les différences observées sur les paramètres de libération in vivo des molécules odorantes sont discutées en regard de ces paramètres physiologiques. Nous avons ainsi observé qu’une viscosité salivaire élevée diminue la quantité de molécules odorantes libérées sur un temps donné. Dans le même temps, la présence d’une quantité importante d’alpha amylase dans la salive augmente de façon significative le temps de libération de la molécule la plus hydrophobe, l’hexanoate d’éthyle. Nous avons ainsi mis en évidence que la rétention des molécules hydrophobes par les protéines salivaires peut induire une modification de leur cinétique de libération en conditions réelles de consommation et pourrait intervenir dans la persistance aromatiqueThe aim of this work is to give a deeper understanding of the impact of the salivary composition on aroma release, by two approaches, an in vitro and an in vivo approach. The impact of salivary proteins on the release of 10 aroma compounds (5 esters and 5 ketones, varying in their hydrophobic chain length) was first investigated by in vitro model systems composed of artificial and human saliva. Artificial salivas were composed of the main salivary proteins, mucins and alpha amylase, alone and in mixture.The amount of aroma released in the vapor phase at equilibrium was analyzed by Static Headspace Gas Chromatography analysis. Air/system partition coefficients have been calculated. This in vitro approach allowed us to demonstrate the ability of both mucin and alpha-amylase to decrease the release of aroma compounds by hydrophobic effect (increase of retention with aroma hydrophobicity). Interestingly, no cumulative effect was observed when both proteins were mixed together in solution. The release of ketones in presence of human saliva is lower than in water and slightly higher than in the presence of artificial saliva. Esters are more affected by the presence of human saliva than ketones. This observation is due to an esterase activity of saliva, which increases with the hydrophobicity of esters. The in vivo release of ethyl propanoate and ethyl hexanoate was followed on ten subjects by Atmospheric Pressure Chemical Ionization mass spectrometry (APCI-MS) under different physiological conditions: at rest, after stimulation and after removing the superficial salivary coat. The saliva was characterized for each subject and each physiological condition. Great variations were observed between the subjects on the salivary flow, viscosity, composition and for each subject between the physiological conditions. The differences observed on in vivo release parameters are discussed as a function of physiological parameters. We observed that subjects with a more viscous saliva present a lower amount of aroma released. The presence of higher amounts of alpha-amylase increased the time needed to release the more hydrophobic compound, ethyl hexanoate. Our results suggest that the retention of hydrophobic aroma compounds by salivary proteins induces a modification of the kinetics of aroma release in real consumption conditions, and could be responsible for aroma persistence
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GASPARD, MARIE. "Conditions de realisation de 222 lymphaphereses chez 32 adultes et 9 enfants lors de traitement par interleukine 2 in vivo et cellules lak." Lyon 1, 1989. http://www.theses.fr/1989LYO1M435.
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De, Vaal Michael Hamman. "In vivo mechanical loading conditions of pectorally implanted cardiac pacemakers : feasibility of a force measurement system and concept of an animal-human transfer function." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/2776.
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Includes abstract.Includes bibliographical references (leaves 92-98).
The objectives of this study were to assess the feasibility of this system for measuring in vivo mechanical loading on pectorally implanted pacemakers, to compare differences in mechanical loading experienced by pacemakers in different pectoral implant positions (i.e. sub-muscular and sub-coetaneous) and to formulate a concept of an interspecific transfer function for predicting the in vivo mechanical loads on sub-muscularly implanted pacemakers in humans, by using data obtained from baboons.
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Valero, Freitag Susana [Verfasser], and Nikolaus [Akademischer Betreuer] Plesnila. "Local and remote effects of pathological conditions on pyramidal neurites : a longitudinal study using in vivo two-photon microscopy / Susana Valero Freitag ; Betreuer: Nikolaus Plesnila." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1220631930/34.
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Féron, François. "Nez, neurones et neurogenèse : analyse in vivo et in vitro des conditions permettant de reproduire le processus de neurogenèse observé dans l'épithélium olfactif de rongeurs adultes." Lyon 1, 1995. http://www.theses.fr/1995LYO10270.
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Cette these a pour objet l'etude des facteurs qui influencent le processus de neurogenese permanent observe dans l'epithelium olfactif des rongeurs. Basee pour l'essentiel sur des travaux realises avec des cultures de cellules prelevees chez l'animal adulte, elle decrit les resultats originaux suivants: les neurones olfactifs matures peuvent etre isoles de maniere tres pure grace a un marquage retrograde et l'utilisation d'un cytometre de flux. Les cellules basales peuvent etre selectionnees et multipliees en culture avec un milieu contenant de l'egf. Les cellules progenitrices sont capables de donner naissance in vitro a des neurones olfactifs apres avoir ete repiquees puis cultivees avec un milieu generalement utilise pour la culture de tissu nerveux. L'insuline et une temperature plus faible que celle du corps favorisent le processus de differenciation des cellules souches. Dans certaines conditions, en particulier lorsqu'elles sont greffees sur du tissu provenant du systeme nerveux central, les cellules nouvellement differenciees perdent une partie de leurs caracteristiques olfactives. L'egf est exprime par les cellules de soutien au cours du processus de regeneration de l'epithelium. La dopamine semble avoir un effet positif sur la stabilisation du caractere mature des neuro-recepteurs
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Chu, Qingjun. "S-allylcysteine (SAC) and S-allylmercaptocysteine (SAMC), water soluble garlic derivatives, suppress growth and invasion of androgen-independent prostate cancer, under in vitro and in vivo conditions." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36749540.
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Chu, Qingjun, and 褚慶軍. "S-allylcysteine (SAC) and S-allylmercaptocysteine (SAMC), water soluble garlic derivatives, suppress growth and invasion of androgen-independent prostate cancer, under in vitro and in vivo conditions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37935653.
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Jain, Arun Kumar [Verfasser]. "Gastrointestinal transit and erosion behavior of gel matrix tablets: Influence of hydroxypropylmethylcellulose (HPMC) molecular weight, concentration, and food intake conditions on in vivo erosion behavior / Arun Kumar Jain." Greifswald : Universitätsbibliothek Greifswald, 2015. http://d-nb.info/1069195405/34.
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Sultan, Sadaf [Verfasser], Giuliano [Akademischer Betreuer] Ramadori, Nils [Akademischer Betreuer] Brose, Michael [Akademischer Betreuer] Hoppert, and Uwe [Akademischer Betreuer] Groß. "Serum Lipocalin-2 (LCN-2) as a major acute phase protein under different pathological conditions in vivo and in vitro studies / Sadaf Sultan. Gutachter: Nils Brose ; Michael Hoppert ; Uwe Groß. Betreuer: Giuliano Ramadori." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://d-nb.info/1042670137/34.
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Sultan, Sadaf Verfasser], Giuliano [Akademischer Betreuer] Ramadori, Nils [Akademischer Betreuer] Brose, Michael [Akademischer Betreuer] Hoppert, and Uwe [Akademischer Betreuer] [Groß. "Serum Lipocalin-2 (LCN-2) as a major acute phase protein under different pathological conditions in vivo and in vitro studies / Sadaf Sultan. Gutachter: Nils Brose ; Michael Hoppert ; Uwe Groß. Betreuer: Giuliano Ramadori." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://nbn-resolving.de/urn:nbn:de:gbv:7-webdoc-3400-1.
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Wright, Victoria Louise. "The role of nicotinic acetylcholine receptors in motivated behaviour." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687374.
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Understanding how memory, learning and reward work in unison to form adaptive and sometime maladaptive behaviour is at the forefront of modern neuroscience. The largest unmet need in treating maladaptive reward learning behaviours such as addiction is maintaining long-term abstinence and preventing relapse after re-exposure to drug-associated cues. Nicotinic acetylcholine receptors (nAChR) have been implicated in responses to drugs of abuse other than nicotine (Rahman et al., 2015) and the aim of this work was to characterise the role of α7 nAChRs in morphine reward learning using conditioned place preference (CPP). The α7 nAChR antagonist methyllycaconitine (MLA) was used to determine if these receptors contribute to specific stages of drug-paired learning, namely acquisition, expression, reconsolidation or reinstatement of morphine-CPP. In 7-8week old C57BL/6J mice MLA (4mg/kg, s.c), given 20 minutes prior to a conditioning dose of morphine (10mg/kg, i.p) or post-test trial, had no effect on the acquisition, reconsolidation or expression of morphine-CPP. However, when given 20 minutes prior to a priming dose of morphine (5mg/kg, i.p), MLA (4mg/kg, s.c) significantly inhibited drug-induced reinstatement. The mechanisms of this effect were investigated using glutamate receptor autoradiography. Changes in 2-Amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid (AMPA) and N-methyl-D-aspartate (NMDA) binding were examined in mice treated with either saline or MLA at morphine reinstatement. There were no significant changes in NMDA receptor binding (using [3H]MK-801) but morphine reinstatement significantly increased [3H]AMPA binding in the CA1/2 of the ventral but not dorsal hippocampus, or in any other brain regions examined (including mPFC, nucleus accumbens, amygdala and VTA). The selective increase in the hippocampus was partially antagonised by MLA, linking α7 nAChR activation to glutamatergic synaptic plasticity in the hippocampus. Intracranial infusions of MLA into the ventral but not the dorsal hippocampus or medial prefrontal cortex blocked reinstatement to morphine-CPP in male Wistar rats.
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Pechloff, Konstanze. "Conditional in vivo expression of the fusion kinase ITK-SYK." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-159471.
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Chaudun, Fabrice. "Involvement of dorsomedial prefrontal projections pathways to the basolateral amygdala and ventrolateral periaqueductal grey matter in conditioned fear expression." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0118/document.
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A l’heure actuelle, une des principales questions des neurosciences comportementales est de comprendre les bases neurales des apprentissages et de comprendre comment des modifications au sein de circuits neuronaux spécifiques contrôlent les changements comportementaux liés à une expérience particulière. De nombreuses études ont récemment mis en évidence le rôle important des circuits neuronaux dans les phénomènes d’apprentissages associatifs, et notamment dans la régulation des comportements de peur. Cependant, leurs caractéristiques anatomiques et fonctionnelles restent encore largement inconnues. L’une des principales fonctions des circuits neuronaux est leur capacité à adapter le comportement en fonction de la nature des informations internes ou environnementales disponibles. Malgré de nombreux progrès réalisés sur la compréhension des substrats et mécanismes neuronaux sous tendant le conditionnement de peur au sein de structures telles que l'amygdale (AMG), le cortex préfrontal dorso-médian (dmPFC) et la substance grise periaqueducale (PAG), les mécanismes neuronaux gouvernant les interactions inter-structure ainsi que le contrôle local de ces différents circuits neuronaux restent encore largement inconnus. Dans ce contexte, ce travail de thèse a eupour objectifs principaux, d’évaluer la contribution des voies de projections dmPFC-BLA et dmPFC-vlPAG dans la régulation des comportements de peur, et, d’identifier les mécanismes neuronaux sous-jacent contrôlant l'expression de la peur. Afin de répondre à ces questions, nous avons utilisé conjointement des enregistrements électrophysiologiques unitaires et de potentiels de champs couplés à des approches optogénétiques au cours de l’expression de la peur conditionnée. Nous avons pu mettre en évidence un nouveau mécanisme neuronal basé sur une oscillation cérébrale à 4 Hz entre le dmPFC et le BLA impliqué dans la synchronisation neuronale des neurones de ces deux structures nécessaire à l’expression de la peur. Nous avons aussi démontré que le dmPFC via ses projections sur le vlPAG contrôle directement l’expression de la peur. Ensemble, nos données contribuent à une meilleure compréhension des circuits neuronaux ainsi que des mécanismes du comportement de peur qui dans le futur pourront aider à une amélioration thérapeutique des troubles anxieuxA central endeavour of modern neuroscience is to understand the neural basis of learningand how the selection of dedicated circuits modulates experience-dependent changes inbehaviour. Decades of research allowed a global understanding of the computations occurring inhard-wired networks during associative learning, in particular fear behaviour. However, brainfunctions are not only derived from hard-wired circuits, but also depend on modulation of circuitfunction. It is therefore realistic to consider that brain areas contain multiple potential circuitswhich selection is based on environmental context and internal state. Whereas the role of entirebrain areas such as the amygdala (AMG), the dorsal medial prefrontal cortex (dmPFC) or theperiaqueductal grey matter (PAG) in fear behaviour is reasonably well understood at themolecular and synaptic levels, there is a big gap in our knowledge of how fear behaviour iscontrolled at the level of defined circuits within these brain areas. More particularly, whereas thedmPFC densely project to both the basolateral amygdala (BLA) and PAG, the contributions ofthese two projections pathway during fear behaviour are largely unknown. Beside theinvolvement of these neuronal pathways in the transmission of fear related-information, theneuronal mechanisms involved in the encoding of fear behaviour within these pathways are alsovirtually unknown. In this context, the present thesis work had two main objectives. First,evaluate the contribution of the dmPFC-BLA and dmPFC-vlPAG pathways in the regulation offear behaviour, and second, identify the neuronal mechanisms controlling fear expression in thesecircuits. To achieve these goals, we used a combination of single unit and local field potentialrecordings coupled to optogenetic approaches in behaving animals submitted to a discriminativefear conditioning paradigm. Our results first, identified a novel neuronal mechanism of fear expression based on the development of 4 H oscillations within dmPFC-BLA circuits thatdetermine the dynamics of freezing behaviour and allows the long-range synchronization offiring activities to drive fear behaviour. Secondly, our results identified the precise circuitry at thelevel of the dmPFC and vlPAG that causally regulate fear behaviour. Together these data provideimportant insights into the neuronal circuits and mechanisms of fear behaviour. Ultimately thesefindings will eventually lead to a refinement of actual therapeutic strategies for pathological conditions such as anxiety disorders
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Faden, Frederik [Verfasser]. "A simple technique for N-end rule-controlled conditional protein accumulation in vivo / Frederik Faden." Halle, 2017. http://d-nb.info/1138641855/34.
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Pechloff, Konstanze [Verfasser], and Daniel [Akademischer Betreuer] Krappmann. "Conditional in vivo expression of the fusion kinase ITK-SYK / Konstanze Pechloff. Betreuer: Daniel Krappmann." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1038152178/34.
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Nakajima, Masaaki. "In Vivo Mechanical Condition Plays an Important Role for Appearance of Cartilage Tissue in ES Cell Transplanted Joint." Kyoto University, 2008. http://hdl.handle.net/2433/124213.
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Lehnertz, Bernhard. "In vivo characterization of the lysine-methyltransferases Set7/9 and G9a by conditional mutagenesis in the mouse." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13027.
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Increasing evidence suggests that site-specific lysine methylation of histone and non-histone proteins is fundamentally involved in epigenetic regulation of gene expression during cellular differentiation and tumorigenesis. To study the in vivo relevance of the lysine methyltransferases Set7/9 and G9a, I have generated and characterized two conditional knockout mouse strains.
Despite its widely proposed role in transcriptional activation through the methylation of histone H3 lysine 4 (H3K4) and a number of transcription factors, I found that Set7/9 knockout mice develop normally and do not display any overt phenotypic alteration. Since Set7/9 was shown to methylate the tumor suppressor protein p53 and was suggested to be important for its activity, I mainly focused my characterization of the Set7/9 knockout strain towards the proposed impairment of p53 function in these mice. Contrary to all reports, I found that in the absence of Set7/9, the p53 target genes p21WAF¹/CIP¹, Mdm2, Puma and Bax are normally expressed under basal and stressed conditions in different cell types. As a consequence, no functional p53 impairment was detectable upon DNA damage or in response to ectopic oncogene expression in Set7/9⁻/⁻ cells. Hence, my data demonstrates that Set7/9-mediated methylation of p53 represents, if at all, only a minor event in its regulation and does not appreciably control p53 activity in vivo.
In the generated conditional G9a knockout strain, I primarily focused my efforts towards describing its role in the hematopoietic system. Mice that conditionally lack G9a expression in the blood, develop normally and can sustain the development of all hematopoietic cell types under homeostatic conditions. Interestingly however, when performing competitive bone marrow transplantation assays, I detected a marked impairment in G9a knockout bone marrow cells in the reconstitution of the hematopoietic system. Consistently, G9a-deficient myeloid and erythroid progenitors are dramatically reduced in their proliferation capacity. My experiments indicate for the first time, that G9a is specifically important for the biology of hematopoietic stem and progenitor cells under stress conditions and its inactivation might represent a promising way to interfere with blood development in pathological and regenerative settings.
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Machiguchi, Toshihiko. "Cellular interactions via conditioned media induce in vivo nephron generation from tubular epithelial cells or mesenchymal stem cells." Kyoto University, 2014. http://hdl.handle.net/2433/189325.
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Jobin, Christine. "Expansion ex vivo des cellules CD34+ du sang adulte : étude du microenvironnement et caractérisation des cellules générées en condition d'hypoxie." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27068.
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Les transplanteurs ont actuellement trois options lorsqu'ils doivent choisir une source de cellules pour la greffe de cellules souches hématopoïétiques soit le sang de cordon, la moelle osseuse ou le sang périphérique mobilisé. Les cellules souches hématopoïétiques retrouvées dans le sang des adultes sains pourraient toutefois être une autre option intéressante pour la transplantation. Les résultats de cette présente étude, récemment publié dans la revue Cytotherapy, montrent le potentiel des cellules CD34+ trappées dans les chambres de leucoréduction à générer les différentes lignées cellulaires retrouvées dans le sang. Un système de culture in vitro en milieu sans sérum et en condition hypoxique a été mis a point. La différenciation des cellules dans l'hématopoïèse durant la culture a été caractérisée par analyse multiparamétrique du phénotype avec SPADE. L'expansion a généré une grande hétérogénéité populationnelle mais principalement des progéniteurs engagés vers l'érythropoïèse et la mégacaryopoïèse.
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Bonneau, Adeline. "Étude de l’impact de la matrice d’un fruit sur la libération et la perception des composés d’arôme en condition in vivo : application à la mangue fraîche ou transformée." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT117/document.
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La perception rétro-nasale (arôme) lors de la mastication en bouche d’un aliment est un phénomène assez complexe. Les compositions physico-chimique et aromatique du produit, son état physique lors de la mastication en bouche, les interactions et réactions mises en jeu dans la cavité buccale sont autant de paramètres qui peuvent influencer cette perception. Dans le cadre de ce travail la mangue sera utilisée comme fruit modèle. Il s’agira de mieux comprendre l’influence du niveau de déstructuration du produit, de la texture ainsi que de la variabilité inter-individuelle d’un panel d’analyse sensorielle sur la perception de l’arôme. La libération des composés volatils lors de la mastication en bouche in vivo du fruit frais, du fruit en forme de purée et du fruit séché sera étudiée par le dispositif RATD(. Le profil aromatique des produits obtenus par la technique SAFE (Solvent assisted flavor evaporation) et les descripteurs aromatiques établis lors de l’analyse sensorielle seront confrontés avec les données RATDRetro-nasal perception of flavor during chewing food in mouth is a complex process. The physico-chemical and aromatic compositions of food, its physical properties, the interactions and reactions involved in oral cavity are the main parameters which can influence flavor perception. In this study, mango is used as model fruit. The study will be focused in better understanding of food disintegration effect, its texture and inter-individual variability on the flavor perception. Liberation of volatile compounds during the chewing of fresh fruit, puree fruit and dried fruit will be studied with RATD (Retronasal aroma trapping device). Fruit volatile profile obtained by SAFE (Solvent assisted flavor evaporation) technique and the aromatic descriptors established during the sensory analysis will be compared with the data from RATD analysis
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Hossain, Md Musharraf. "Interactions between Vitamin D, Breast Cancer and Mesenchymal Stem Cells: In Vitro And in Vivo Perspectives." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18682.
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The active metabolite of vitamin D, 1α25-Dihydroxy vitamin D3 (1α25 (OH)2D3) is known to be an inhibitor of breast cancer cell growth. However, actions of its precursors 25(OH)D and Vitamin D have not been fully investigated. Mesenchymal stem cells (MSCs) have been identified as regulators of cancer growth, however the effects of 1α25 (OH)2D3 on these actions is unknown. MDA-MB231 and MCF7 cells were evaluated for direct effects of 1α25 (OH)2D3, 25(OH) D3 and vitamin D3 on their proliferation and invasiveness. The effect of 1α25 (OH)2D3 on expressed factors in MSC conditioned media (CM) was assessed by microarray. Treatment of MDA-MB-231 and MCF7 cells with vitamin D3 did not inhibit cell growth but increased apoptosis and decreased invasiveness. Gene expression of CYP24 did not change indicating no activation of vitamin D receptor (VDR) signalling. Treatment of MDA-MB-231 and MCF7 cells with MSCs CM increased cell growth, and treatment with 1α25(OH)2D3 or vitamin D3 pre-treated MSCs CM increased this further. Genomic microarray analysis of MDA-MD-231 and MCF7 breast cancer cells and of MSCs identified STAT3 and PDE4D as possible master mediators of the increased proliferation induced by CM from MCSs pre-treated with 1,25(OH)2D3. It also identified activation of signalling pathways STAT3, VDR/RXR, IL-6, IL-17, JAK/STAT3, CXCR4 for MDA-MB-231 and STAT3, NF-kB, ER/MAPK, HGF, IL-6 for MCF-7 cells. The effect of VDR knock down (KD) on breast and prostate cancer cell growth and tumour formation was studied in a mouse xenograft model. VDR knockdown in breast and prostate cancer cells decreased their tumour growth suggesting that the un-liganded VDR may have itself have proliferative actions which may present therapeutic a target in breast cancer and prostate cancer. The findings indicate that VDR, vitamin D and its metabolites can control cell growth during breast cancer by direct actions on cells, or indirectly by modulating the effects of MSCs on adjacent cancer cells.
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Morehead, Melissa L. "Shaping Cows' Approach to Humans Using Positive and Negative Reinforcement." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4730/.
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Negative reinforcement can be a powerful tool for behavior analysts, yet it is often overlooked as a treatment method. Pryor (1999) outlines a method for approaching a "timid" animal using a combination of negative reinforcement and positive reinforcement. When the animal stands still, the human operates a clicker, and then retreats from the animal. Gradually, the human moves closer to the animal through the clicking and retreating shaping process. Once the human is standing close enough, food may be offered as a positive reinforcer, and the negative reinforcer is canceled out. The purpose of this study was to experimentally demonstrate the click-retreat technique with cows. A multiple-baseline design across subjects was used to test this technique. Results show that the click and retreat technique was effective. Results are discussed in terms of the difference between the click-retreat technique and systematic desensitization.
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Alsheikh, Manal. "Impact of the Maturation Status of Osteoblasts on Their Hematopoietic Regulatory Activity." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35899.
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Osteoblasts (OST) provide strong intrinsic growth modulatory activities on hematopoietic stem and progenitor cells via different mechanisms that include secretion of growth factors, and cellular interaction. Previously we showed that medium conditioned by mesenchymal stromal cell (MSC)-derived osteoblasts (M-OST) improve the expansion of cord blood (CB) CD34+ cells. I hypothesize that the hematopoietic supporting activity of M-OST would vary as a function of their maturation. This was tested by producing osteoblast conditioned media (OCM) from M-OST at distinct stages of maturation, and testing their growth regulatory activities in CB CD34+ cell cultures. My results showed that some of the growth promoting activity of OCM on CB cells are not dependent on the maturation status, while others are and those are largely independent of Notch signalling. In conclusion, these results provide further evidence that osteoblasts release factors that can promote the growth of immature CB progenitors in a Notch-independent way.
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Thomas, R. M. "Csk is an important negative regulator of phagocyte responsiveness in vivo : characterisation of myeloid cell-specific Csk deficiency in mice by conditional mutagenesis (Cre/loxP)." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445173/.
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Whilst the recruitment of phagocytic leukocytes is fundamental to the innate response against pathogenic infection, the inappropriate mobilisation of their cytotoxic potential can also lead to fatal tissue injury. To determine the contribution of Csk, a negative regulator of Src family kinases, to the regulation of phagocyte recruitment and activation in vivo, mice lacking Csk in the myeloid lineage were generated using conditional mutagenesis (cre/loxP). This Csk deficiency resulted in acute multifocal inflammation in skin and lung, accompanied by extramedullary haematopoiesis in the spleen and liver, and increased myelopoiesis in bone marrow. Animals were protected from the disease in a microbiologically controlled environment, but remained hypersensitive to LPS-induced shock. Csk-deficient granulocytes showed enhanced spontaneous and ligand-induced degranulation accompanied by hyperinduction of integrins. Hyperresponsiveness was associated with hyperadhesion and impaired migratory responses in vitro. Biochemical studies revealed spontaneous accumulation of tyrosine-phosphorylated proteins, including hyperphosphorylation of key signalling proteins including Syk and paxillin. These data support a breakdown of the activation threshold set by Csk. Thus, Csk is critical in preventing premature granulocyte recruitment through enforcing the requirement for ligand engagement while supporting the migratory capacity of activated cells through negative regulation of cell adhesion. To address the incomplete Cre mediated deletion of floxed genes in vivo, a genetic approach to elevate Cre recombinase gene expression was developed. Whilst manipulation of regulatory elements including promoter, enhancer, and untranslated regions has yielded enhanced and sustained expression in vitro, this has been difficult to achieve in vivo. Here, it is reported that construction of artificial exons through insertion of short heterologous intron sequences into the open reading frames of the Cre recombinase and enhanced green fluorescent protein results in functional expression accompanied by a 30-fold increase in transcription levels in vitro. Furthermore, green fluorescence levels were enhanced five-fold in cell lines and enhanced considerably in the rat brain after transduction with a herpes simplex virus-based vector. These data define a method of improving both the level and duration of recombinant gene expression, in addition to and independently of surrounding regulatory elements. Significantly, the method should help to increase Cre recombinase expression from weak or transiently expressed promoters thus overcoming an important limitation of Cre/loxP technology incomplete deletion. Furthermore, this method may also be applicable in gene therapy to obtain sustained and effective expression of recombinant proteins in vivo.
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Manfredi, I. "In vivo study of mutant nicotinic receptor's role in the pathogenesis of autosomal dominant nocturnal frontal lobe epilepsy : development and characterization of a conditional mouse model." Doctoral thesis, Università degli Studi di Milano, 2008. http://hdl.handle.net/2434/63073.
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Jokela, T. (Tiina). "Analyses of kidney organogenesis through in vitro and in vivo approaches:generation of conditional Wnt4 mouse models and a method for applying inducible Cre-recombination for kidney organ culture." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526201559.
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Abstract In mice, gene targeting has become a useful tool for resolving the functions of proteins and for creating new animal models. Cre/loxP technology has been used broadly for generation of genetically modified mice. The Cre recombinase recognizes a specific DNA sequence, called loxP, and removes any DNA fragment between two loxP-sites. The activity of the Cre recombinase can be controlled spatially and temporally with cell- or tissue-specific promoters and synthetic inducing agents, such as tamoxifen or tetracycline. In this thesis, we employed tamoxifen-induced Cre recombination in vitro. Cre-ERTM mice were crossed to ROSA26LacZ reporters and Cre-recombination induced by 4OH-TM was monitored by LacZ staining. 0.5 μM 4OH-TM treatment was competent for tamoxifen-induced Cre-mediated activation of LacZ both in kidney cultures and in experimentally induced kidney mesenchymes. Wnt4 is a secreted signaling molecule, which is necessary for the development of several organs including kidney, ovary, adrenal gland, mammary and pituitary glands. Wnt4 is crucial for kidney development and conventional Wnt4-/- mice die soon after birth, likely due to renal failure. In this thesis, two different Wnt4 alleles, Wnt4EGFPCre and floxed Wnt4, were generated and analyzed to learn more about the Wnt4 functions and to apply these mouse lines to renal functional genomics. In the Wnt4EGFPCre, the EGFPCre fusion cDNA was targeted into exon I of the Wnt4 locus. EGFP-derived fluorescence was observed in the pretubular aggregates from E12.5 embryonic kidney onwards. Further characterization by crossing with the floxed ROSA26LacZ and yellow fluorescent protein (YFP) reporter lines demonstrated that in addition to the kidney, reporter expression was observed in the gonad, spinal cord, lung and the adrenal gland. The expression pattern of the Cre activity recapitulates well the known pattern of the Wnt4 gene. Time-lapse analysis in organ culture settings showed that the Wnt4 expressing cells contributed to the nephrons, some cells near the stalk of the developing ureter, as well as a number of positive supposed medullary stromal cells. In the conditional Wnt4 knock-out, loxP sites were placed to flank exons 3 to 5. The Wnt4 gene was specifically inactivated with CAGCre and Wnt4EGFPCre lines. In both of these crosses deletion of Wnt4 gene function led to impaired kidney development. In conclusion, we identified the culture conditions that can be used for the tamoxifen-induced conditional mutagenesis in tissue cultures. In addition, the created Wnt4 mouse lines serve as new useful tools for addressing the roles of Wnt4 function in diverse tissues and in different stages of developmentTiivistelmä Hiirillä geenikohdennuksesta on muodostunut hyödyllinen väline proteiinien tehtävien selvittämisessä ja uusien eläinmallien luomisessa. Cre/loxP -tekniikkaa on käytetty laajasti muuntogeenisten hiirien tuottamisessa. Cre-rekombinaasi tunnistaa spesifisen DNA-jakson, niin kutsutun loxP:n, ja poistaa kaikki DNA-jaksot kahden loxP-sekvenssin väliltä. Cre-rekombinaasin aktiivisuutta voidaan säädellä paikallisesti ja ajallisesti solu- tai kudosspesifisillä promoottoreilla ja synteettisillä indusoivilla kemikaaleilla, kuten tamoksifeenillä tai tetrasykliinillä. Tässä väitöskirjassa hyödynsimme tamoksifeenin aiheuttamaa Cre-rekombinaatiota in vitro -kudosviljelmissä. Cre-ERTM-hiirilinja risteytettiin ROSA26LacZ-reportterilinjan kanssa, ja 4-hydroksitamoksifeenin indusoima Cre-rekombinaasin aktiivisuutta monitoroitiin LacZ–värjäyksellä. 0.5 µM:n 4OH-TM konsentraatiolla LacZ-reportterigeeni saatiin aktivoitua tehokkaasti Cre-rekombinaasin avulla sekä munuaisviljelmissä että munuaismesenkyymiviljelmissä. Wnt4 on erittyvä signalointimolekyyli, jolla on keskeinen rooli useiden elinten, kuten munuaisen, munasarjan, lisämunuaisen, rintarauhasen ja aivolisäkkeen kehittymisessä. Wnt4-geenillä on ratkaisevan tärkeä rooli munuaisen kehityksessä, ja poistogeeninen Wnt4-/-hiiri kuolee pian syntymän jälkeen, todennäköisesti munuaisen vajaatoimintaan. Tässä väitöskirjatyössä tuotettiin kaksi eri Wnt4 alleelia, Wnt4EGFPCre ja konditionaalinen Wnt4. Nämä hiirilinjat analysoitiin, jotta saisimme lisää tietoa Wnt4-geenin toiminnasta ja pystyisimme soveltamaan kyseisiä hiirikantoja munuaisten toiminnan selvittämisessä. Wnt4EGFPCre-alleelissa EGFPCre-fuusio -cDNA kohdennettiin osaksi endogeenisen Wnt4-geenin ykköseksonia. Vihreän fluoresoivan proteiinin (EGFP) aktiivisuus havaittiin varhaisen munuaisen kehityksen aikana. Wnt4EGFPCre-alleelin lisäkarakterisointi reportterilinjoilla (Rosa26LacZ ja Rosa26YFP) osoitti, että Wnt4-geenin ilmentyminen havaittiin munuaisen lisäksi sukurauhasissa, selkäytimessä, keuhkoissa sekä lisämunuaisessa. Wnt4EGFPCre-alleeli ilmentyi niissä kudoksissa, joissa endogeenisen Wnt4-geenin tiedetään olevan aktiivinen. Time-lapse -analyysin avulla osoitettiin, että Wnt4-geeniä ilmentävät solut muodostavat tiettyjä rakenteita munuaisen kehityksen aikana. Wnt4-geeni ilmentyi nefroneissa, kehittyvän virtsajohtimen soluissa sekä useissa medullaarisissa stroomasoluissa. Konditionaalisessa (ehdollisessa) Wnt4 knock-out-hiirilinjassa loxP-sekvenssit sijoitettiin eksonien kolme sekä viisi ympärille. Wnt4-geenin toiminta inaktivoitiin CAGCre- ja Wnt4EGFPCre-hiirilinjojen avulla. Näissä molemmissa tapauksissa Wnt4-geenin toiminnan poistaminen johti munuaisen kehityshäiriöön. Yhteenvetona voimme todeta, että olemme tunnistaneet ne kasvatusolosuhteet, joita voidaan hyödyntää, kun halutaan aktivoida reportterigeenejä tai kehityksen kannalta tärkeitä geenejä tamoksifeenin aiheuttamaa Cre/loxP -rekombinaatiota hyväksikäyttäen kudosviljelmissä. Samoja olosuhteita ja menetelmää käyttäen voidaan myös poistaa jonkun kehityksen kannalta tärkeän geenin toiminta ja tutkia sitä kudosviljelmässä. Tuotetut Wnt4-hiirikannat ovat lisäksi uusia hyödyllisiä työkaluja, kun halutaan tutkia Wnt4-geenin toimintaa erilaisissa kudoksissa ja eri kehitysvaiheiden aikana
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Akella, Arun. "A novel in vitro stretch device for simulating in vivo conditions." Thesis, 2018. https://doi.org/10.7912/C2B36V.
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Indiana University-Purdue University Indianapolis (IUPUI)Biological cells are constantly subjected to mechanical forces such as tension, compression and shear. The importance of these forces in mediating cell signals, maintenance of lineages, promoting embryonic cell differentiation and tissue engineering is only now coming into focus. It has been shown that stretch stimulus can influence growth, differentiation, as well as tissue strength and integrity. Most stretch systems built to understand more of these phenomena suffer from shortcomings, as accurately replicating the in vivo environment is quite challenging. Many of the devices currently available are very expensive as well as limited to a single application. The objective of this thesis is to design, manufacture, test, and validate a novel uniaxial cyclic cell stretch device that overcomes most of the major limitations of existing systems, and to experimentally demostrate that uniaxial cyclic stretch causes a shift towards in vivo characteristics of smooth muscle cells. The stretch mechanism is driven by a single servo motor which makes its operation simple and straight forward. Coolworks Lite, a proprietary software of the servo motor supplier, is used to control the motor and LabVIEW is used to obtain feedback from the sensors. Validation for the stretch machine was done by evaluating the performance of the device against engineering requirements. Methods were suggested to improve shortcomings that were encountered. Also, the machine's unique design allows its extension to a biaxial stretch unit while keeping the same driver platform, a concept for which has been discussed and illustrated.
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Carlson, Kristen Dawn. "Fiber optic confocal microscope: in vivo precancer detection." Thesis, 2006. http://hdl.handle.net/2152/2471.
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Kursa, Katarzyna. "Effects of external loading conditions on in vivo forces generated by finger flexor muscles /." 2004. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3136091.
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Liu, Fei. "Theoretical modeling and experimental validation of in vivo mechanics for subjects having variable cervical spine conditions." 2007. http://etd.utk.edu/2007/LiuFei.pdf.
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