Comparison of Autografts vs. Allografts in the Surgical Repair of Pediatric Obstetrical Brachial Plexus Injuries

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.Obstetrical Brachial Plexus Injuries(OBPI) occur during delivery with a global incidence ranging from 0.2- 4% of live births, and generally, prognosis is excellent with spontaneous recovery in up to 95% of patients. For patients with OBPI that do not obtain a functional recovery by 4-6 months of life, treatment is primarily surgical in nature. Surgical treatment involves testing of the nerves to determine whether they remain connected distally and proximaly, removal of scar tissue/ neurolysis, and then bridging the nerve discontinuity or block with a nerve graft. Nerve grafting provide a three-dimensional extracellular matrix that promotes Schwann cell migration and axon regeneration. Historically, nerve graft was autograft using sural nerve. More recently, a decellularized processed cadaveric nerve allograft (Axogen) has been utilized in numerous peripheral nerve injury repairs, mostly in adults, but has not been reportedly used in pediatric OBPI. The aim of this study is to determine if using nerve allografts (Axogen) will have similar functional outcomes as compared to sural nerve autografts in reconstruction of the brachial plexus after OBPI.This item is part of the College of Medicine - Phoenix Scholarly Projects 2019 collection. For more information, contact the Phoenix Biomedical Campus Library at [email protected]

Regulatory Role of Cell Division Rules on Tissue Growth Heterogeneity

The coordination of cell division and cell expansion are critical to normal development of tissues. In plants, cell wall mechanics and the there from arising cell shapes and mechanical stresses can regulate cell division and cell expansion and thereby tissue growth and morphology. Limited by experimental accessibility it remains unknown how cell division and expansion cooperatively affect tissue growth dynamics. Employing a cell-based two dimensional tissue simulation we investigate the regulatory role of a range of cell division rules on tissue growth dynamics and in particular on the spatial heterogeneity of growth. We find that random cell divisions only add noise to the growth and therefore increase growth heterogeneity, while cell divisions following the shortest new wall or along the direction of maximal mechanical stress reduce growth heterogeneity by actively enhancing the regulation of growth by mechanical stresses. Thus, we find that, beyond tissue geometry and topology, cell divisions affect the dynamics of growth, and that their signature is embedded in the statistics of tissue growth.Engineering and Applied Science

Faire accepter les lieux de réduction des risques : un enjeu quotidien

Les professionnels de la Réduction des risques, qui accueillent et accompagnent les usagers de drogues, connaissent des difficultés à faire reconnaitre et accepter leur mission de Santé publique. Que ce soit par peur de la différence, des états de conscience modifiés, pour des raisons morales ou au regard de la loi, les riverains des dispositifs de RdR mettent en question la présence des usagers à leurs côtés. Pour leur répondre, la médiation sociale est inscrite au coeur des missions des Centres d'accueil et d'accompagnement à la réduction des risques des usagers de drogues (CAARUD), principal levier pour permettre l'acceptabilité des dispositifs. Quelles sont les formes données à la médiation mise en oeuvre par les professionnels de la RdR? Cette étude financée par la Direction générale de la santé (DGS) répond à cette question. Elle propose ainsi un état des lieux bibliographique des études, guides et observations faites autour de cette question, complété par le recueil détaillé des pratiques professionnelles dans un certain nombre de dispositifs de RdR. Enfin, une troisième et dernière partie reprend, sous forme de recommandations, les principaux enjeux liés à la mise en place d'un nouveau lieu d'accueil. Sont ici identifiées les étapes nécessaires à la mise en lien entre les dispositifs de RdR et leurs partenaires, qu'ils soient institutionnels (Agences régionales de santé, municipalités, communautés de communes, forces de l'ordre, services sociaux...) ou privés (bailleurs, commerçants, voisins...). Ce sont autant d'interlocuteurs de la médiation sociale, ressources pour permettre aux porteurs de projets de concevoir une démarche concertée d'implantation

The 1972 Meadows report: A wake-up call for plant science

The 1972 Meadows report, ‘the limits to growth’, predicted a global socio-economic tipping point during the twenty-first century. Now supported by 50 years of empirical evidence, this work is a tribute to systems thinking and an invitation to take the current environmental crisis for what it is: neither a transition nor a bifurcation, but an inversion. For instance, we used matter (e.g., fossil fuel) to save time; we will use time to preserve matter (e.g., bioeconomy). We were exploiting ecosystems to fuel production; production will feed ecosystems. We centralised to optimise; we will decentralise to support resilience. In plant science, this new context calls for new research on plant complexity (e.g., multiscale robustness and benefits of variability), also extending to new scientific approaches (e.g., participatory research, art and science). Taking this turn reverses many paradigms and becomes a new responsibility for plant scientists as the world becomes increasingly turbulent

The RNA Polymerase-Associated Factor 1 Complex Is Required for Plant Touch Responses

Thigmomorphogenesis is a stereotypical developmental alteration in the plant body plan that can be induced by repeatedly touching plant organs. To unravel how plants sense and record multiple touch stimuli we performed a novel forward genetic screen based on the development of a shorter stem in response to repetitive touch. The touch insensitive (ths1) mutant identified in this screen is defective in some aspects of shoot and root thigmomorphogenesis. The ths1 mutant is an intermediate loss-of-function allele of VERNALIZATION INDEPENDENCE 3 (VIP3), a previously characterized gene whose product is part of the RNA polymerase II-associated factor 1 (Paf1) complex. The Paf1 complex is found in yeast, plants and animals, and has been implicated in histone modification and RNA processing. Several components of the Paf1 complex are required for reduced stem height in response to touch and normal root slanting and coiling responses. Global levels of histone H3K36 trimethylation are reduced in VIP3 mutants. In addition, THS1/VIP3 is required for wild type histone H3K36 trimethylation at the TOUCH3 (TCH3) and TOUCH4 (TCH4) loci and for rapid touch-induced upregulation of TCH3 and TCH4 transcripts. Thus, an evolutionarily conserved chromatin-modifying complex is required for both short- and long-term responses to mechanical stimulation, providing insight into how plants record mechanical signals for thigmomorphogenesis

The self-organization of plant microtubules inside the cell volume yields their cortical localization, stable alignment, and sensitivity to external cues.

Many cell functions rely on the ability of microtubules to self-organize as complex networks. In plants, cortical microtubules are essential to determine cell shape as they guide the deposition of cellulose microfibrils, and thus control mechanical anisotropy of the cell wall. Here we analyze how, in turn, cell shape may influence microtubule behavior. Building upon previous models that confined microtubules to the cell surface, we introduce an agent model of microtubules enclosed in a three-dimensional volume. We show that the microtubule network has spontaneous aligned configurations that could explain many experimental observations without resorting to specific regulation. In particular, we find that the preferred cortical localization of microtubules emerges from directional persistence of the microtubules, and their interactions with each other and with the stiff wall. We also identify microtubule parameters that seem relatively insensitive to cell shape, such as length or number. In contrast, microtubule array anisotropy depends on local curvature of the cell surface and global orientation follows robustly the longest axis of the cell. Lastly, we find that geometric cues may be overcome, as the network is capable of reorienting toward weak external directional cues. Altogether our simulations show that the microtubule network is a good transducer of weak external polarity, while at the same time, easily reaching stable global configurations