The compartmental hypothesis of neurodegeneration proposes that the neurone, long recognized to consist of morphologically and functionally distinct compartments, also houses distinct degeneration mechanisms for the soma, axon and nerve endings. Support for this hypothesis is provided by the phenomenon of the WldS (for Wallerian Degeneration, slow) mouse, a mutant in which axons survive several weeks after transection, rather than degenerating within 24-48 hours as in wild type mice, by virtue of expression of a chimeric Nmnat1/Ube4b protein. In this thesis I used the WldS-mouse to re-examine and extend the theory of compartmental neurodegeneration by focusing specifically on sensory axons and endings; and finally by considering a fourth compartment, the dendrites. The first part of this thesis reports that Ia afferent axons and their annulospiral endings are robustly protected from degeneration in WldS mice. Homozygous or heterozygous WldS mice crossbred with transgenic mice expressing fluorescent protein in neurones were sacrificed at various times after sciatic nerve transection. Fluorescence microscopy of whole mount preparations of lumbrical muscles in these mice revealed excellent preservation of annulospiral endings on muscle spindles for at least 10 days after axotomy. No significant difference was detected in the protection with age or gene copy-number in contrast to the protection of motor nerve terminals, which degenerate rapidly in heterozygote and aged homozygote WldS mice. In an attempt to explain the difference in motor and sensory protection by WldS, examination of three hypotheses was undertaken: a) differences in protein expression, tested by western blot and immunohistochemistry; b) differences in the degree of neuronal branching, tested through examination of g-motor axons and endings which have a degree of branching intermediate to motor and sensory neurons; and c) differences in the activity in the disconnected stumps, through primary culture of the saphenous and phrenic nerve, selected because they comprise largely pure sensory and motor axons respectively. The data suggest that none of these hypotheses provides a sufficient explanation for the difference between sensory and motor protection by WldS. The last part of this thesis attempts to extend the theory of compartmental degeneration. I examine a system for investigation of WldS-mediated protection of dendrites. In preliminary experiments retinal explants from transgenic mice expressing YFP in a subset of retinal ganglion-cell neurones were cultured. The dendritic arbours of these cells were shown to be amenable for repeated visualization and accessible to injury and monitoring of degeneration. Overall the data in this thesis suggest that the level of WldS -mediated protection conferred to an axon or axonal endings varies between different neuronal types. This has implications for the potential applications of WldS research to clinical problems. Specifically, the data imply that sensory neuropathies may benefit more than motor neuropathies from treatments based on the protective effects of WldS. These findings in sensory neurones also challenge some of the assumptions made about WldS- mediated protection of neurones, for example the extent of the age-effect on axonal endings. Further investigation of WldS-mediated protection in the CNS could give renewed impetus to attempts to discover targets for treatment in common neurodegenerative diseases. Finally, a system for investigation of dendritic degeneration has been piloted, suggesting that molecules involved in the degeneration of dendrites or in protection from this degeneration may be amenable to investigation in this system, prospectively extending the compartmental hypothesis of neuronal degeneration.

Magnocellular neurones (MCNs) are capable of secreting vasopressin and oxytocin from the somato-dendritic compartment, which can occur independently to secretion from nerve terminals. One hypothesis of the mechanism that regulates this differential release is that dendrites utilise different vesicle pools compared to those found in terminals. Little is known for the function of neuronal dendrites, especially the mechanism for peptide release. One theory is that vesicles stored in dendrites are non-released vesicles ready for recycling or degradation. Immunofluorescent labelling was performed on hypothalamic slices of the transgenic rat where enhanced green fluorescent protein (eGFP) was tagged to vasopressin. Lysosomes were detected by the lysosome-associated membrane protein LAMP1. Correlation analysis of LAMP1 labelling and VP-eGFP had shown that localisation of lysosomes in dendrites is positively correlated to loci of high vasopressin expression. This suggests active degradation of vesicles in dendrites. It is not known whether preferential release of peptides occurs along the profile of dendrites. Experiments were carried out using a temperature block to block exit of vesicles from the Golgi apparatus. Release of the temperature block triggered release of a wave of newly synthesised vesicles from the Golgi apparatus. Measurement of the fluorescent intensity of VP-eGFP showed that preferential release of peptides does not occur along the profile of dendrites. I have also utilised confocal live cell imaging to study the dynamics of dendritic vasopressin release using VP-eGFP slice explants. Experiments using high potassium stimulation showed significant increase in the release of vasopressin after priming with thapsigargin (intracellular calcium mobiliser), in accordance to in vitro release and microdialysis studies. These results demonstrate that live cell imaging can be achieved in magnocellular neurons, providing a robust model system in the study of dendritic peptide release. Large dense core vesicles (LDCVs) in other cell types such as bovine adrenal chromaffin cells were shown to segregate according to vesicle age, suggesting that vesicle age is an important factor in the regulation of peptide release. Whether vesicles of different age groups exist in magnocellular dendrites is not known. Thus, biolistic transfection with exogenous fluorescent proteins for expression under temporal control was carried out. However, low transfection rate in magnocellular neurones and the high background fluorescence caused by scattered gold particles used as bullets for transfection deemed this method inappropriate for the purpose of imaging vesicles. Hence, development of an adenoviral transduction system was employed. By using an inducible adenovirus gene construct coupled with a fluorescent reporter gene, it is possible to visualise vesicle pool segregation under different experimental conditions. Subcloning of a red fluorescent construct tagged to ppANF was tested on PC12 cells to show targeting of fluorescence expression to LDCVs. Successful production of an inducible adenoviral DNA with the red fluorescent construct insert was confirmed by PCR and DNA sequencing. Whilst the generation of viral particles is still to be achieved, successful production of the virus will be an invaluable system for inducible gene expression in neurones.

Different types of alumina containing coatings were made on lithiumand copper in the purpose to mechanically hinder the growth ofdendrites. Lithium, coated with polymer-alumina composites wereplaced in symmetric cells for in situ studies by a light microscope.The coatings did not block the dendrites, but they did change thegrowth rate and morphology of them, probably throw both chemicalinteractions and changes in ion transportation. Also the stability ofcapacity were tested for the same coatings, the result showed abigger capacity drop for cells containing coated lithium versus cellswithout coatings.Attempted alumina coatings were also made by a solgel technique, bydirect reaction with the compound trimethylaluminium and with analumina containing acetonitrile solution.The theses also includes a study of the stability of lithium inadiponitrile. A higher amount of LiTFSI salt in adiponitrile could bythis study be reported to inhibit the dissolution of lithium that wasseen for lower salt concentrations. The dissolution appeared when thesolution was used as an electrolyte in a symmetric lithium cell. Somedifferences could be seen when the lithium surface were studied byXPS after interaction with high, low and zero concentration LiTFSI.Both the XPS studies and the absences of lithium dissolutionindicates that a more or less stable SEI had been formed.

Organisms possess internal sensory systems to detect changes in physiological state. Despite the importance of these sensory systems for maintaining homeostasis, their development, sensory mechanisms, and circuitry are relatively poorly understood. To help address these gaps in knowledge, I used the tracheal dendrite (td) sensory neurons of Drosophila larvae as a model to gain insights into the cellular and molecular organization, developmental regulators, sensory functions and mechanisms, and downstream neural circuitry of internal sensory systems. In this thesis, I present data to show that td neurons comprise defined classes with distinct gene expression and axon projections to the CNS. The axons of one class project to the subesophageal zone (SEZ) in the brain, whereas the other terminates in the ventral nerve cord (VNC). This work identifies expression and a developmental role of the transcription factor Pdm3 in regulating the axon projections of SEZ-targeting td neurons. I find that ectopic expression of Pdm3 alone is sufficient to switch VNC-targeting td neurons to SEZ targets, and to induce the formation of putative synapses in these ectopic target regions. These results define distinct classes of td neurons and identity a molecular factor that contributes to diversification of central axon targeting. I present data to show that td neurons express chemosensory receptor genes and have chemosensory functions. Specifically, I show that td neurons express gustatory and ionotropic receptors and that overlapping subsets of td neurons are activated by decrease in O2 or increase in CO2 levels. I show that respiratory gas-sensitive td neurons are also activated when animals are submerged for a prolonged duration, demonstrating a natural-like condition in which td neurons are activated. I assessed the roles of chemosensory receptor genes in mediating the response of td neurons to O2 and CO2. As a result, I identify Gr28b as a mediator of td responses to CO2. Deletion of Gr28 genes or RNAi knockdown of Gr28b transcripts reduce the response of td neurons to CO2. Thus, these data identify two stimuli that are detected by td neurons, and establish a putative role for Gr28b in internal chemosensation in Drosophila larvae. Finally, I present data to elucidate the neural circuitry downstream of td sensory neurons. I show that td neurons synapse directly and via relays onto neurohormone populations in the central nervous system, providing neuroanatomical basis for internal sensory neuron regulation of hormonal physiology in Drosophila. These results pave the way for future work to functionally dissect the td circuitry to understand its function in physiology and behavior.

abstract: ABSTRACT Programmable metallization cell (PMC) technology uses the mechanism of metal ion transport in solid electrolytes and electrochemical redox reactions to form metallic electrodeposits. When a positive bias is applied from anode to cathode, atoms at the anode are oxidized to ions and dissolve in the solid electrolyte. They travel to the cathode under the influence of an electric field, where they are reduced to form electrodeposits. These electrodeposits are filamentary in nature and grow in different patterns. Devices that make use of the principle of filament growth have applications in memory, RF switching, and hardware security. The solid electrolyte under investigation is tungsten trioxide with copper deposited on top. For a standard PMC, these layers are heated in a convection oven to dope the electrolyte. Once the heating process is completed, electrodes are deposited on top of the electrolyte and biased to grow the filaments. What is investigated is the rate of dendritic growth to applied field on the PMC and the composition of the electrolyte. Also investigated are modified three-terminal PMC capacitance change devices. These devices have a buried sensing electrode that senses the increasing capacitance as the filaments grow and increase the upper electrode area. The rate of dendritic growth in the tungsten trioxide and copper electrolyte of different chemistries and applied field to the PMC devices is the important parameter. The rate of dendritic growth is related to the change of capacitance. Through sensing the change in capacitance over time the modified PMC device will function as an odometer device that can be attached to chips. The attachment of these devices to chips, help in preventing illegal recycling of old chips by marking those chips as old. This will prevent would-be attackers from inserting modified chips in systems that will enable them to by-pass any software security precautions. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

El ácido docosahexaenoico, un PUFA omega-3, se ha relacionado con efectos inmunosupresores en linfocitos, monolitos y macrófagos pero no existían estudios sobre sus efectos en las células dendríticas (DCs). Por ello se diferenciaron en presencia de DHA monocitos hacia DCs. Las células tratadas con el ácido graso mostraron cambios fenotípicos divergentes en función del estadio de madurez de las mismas. Así, en estadio inmaduro, se produjeron incrementos de expresión de CD83, CD86, HLA-DR y CD36 y disminución de CD1a y CD80. Sin embargo, en estadio maduro, CD83, CD86 y HLA-DR sufrieron descensos en su expresión con respecto a los controles. CD80 y CD1a de nuevo presentaban una expresión disminuida y la de CD36 se encontraba aumentada. Al medir la capacidad de activación de la proliferación linfocitaria de estas células se encontró que esta se encontraba disminuida. La secreción de IL-10 e IL-12 también había disminuido. Este conjunto de efectos era dependiente de la concentración de DHA. El DHA era capaz de desarrollar algún tipo de efecto inmunosupresor en las DCs.Se realizaron experimentos similares con otros ácidos grasos: EPA, ácido linoleico (LA) y ácido oleico. Con EPA y LA se obtuvieron resultados similares a los mostrados por el DHA cualitativamente pero no cuantitativamente. El DHA era el ácido graso más potente y afectaba tanto al fenotipo como a la capacidad secretora de citocinas y activadora de la proliferación linfocitaria en DCs.Estos resultados eran similares a los obtenidos por otros autores en los tratamientos de DCs con activadores de PPARγ lo cual sugería para el DHA una posible actuación a través de este receptor nuclear. Sin embargo, el hecho de que el DHA sea un activador de PPARγ pobre en comparación con EPA, LA o Rosiglitazona sugirió la presencia de otras vías de activación. En concreto, RXR, con el cual se ha demostrado que el DHA es capaz de interactuar.Se trataron DCs con concentraciones en el rango nanomolar de 9cRA, un activador de RXR, obteniéndose que este retinoide era capaz de interferir en la maduración normal de la DC de forma que se obtenía resultados fenotípicos extraordinariamente similares a los producidos por el DHA. También la capacidad de estimulación de la proliferación linfocitaria estaba disminuida. En cambio, las DCs tratadas con 9cRA mostraron una secreción disminuida de IL-12 y normal de IL-10. La activación de PPARγ:RXR simultáneamente a través de ambos monómeros ha sido relacionada con efectos aditivos, sinérgicos o complementarios en muchos tipos celulares. Se cree que esto es debido a la unión de moléculas coactivadoras complementarias al heterodímero. La adición simultánea de Rosiglitazona y 9cRA a las DCs mostró efectos fenotípicos aditivos indicando que probablemente 9cRa estaba actuando a través del heterodímero. Se realizaron experimentos similares combinando el DHA con 9cRA y el DHA con la Rosiglitazona. La combinación con Rosiglitazona mostró cambios mucho más importantes lo cual sugería que el DHA actuaba principalmente uniéndose a RXR en el heterodímero. Finalmente se añadió un inhibidor específico de PPARγ a las células dendríticas: GW9662; el cual fue capaz de bloquear los efectos producidos por el DHA, la Rosiglitazona y el 9cRA. Además, el inhibidor por sí mismo alteraba por completo el proceso de maduración de las células dendríticas implicando que PPARγ debe desarrollar un papel indispensable en el proceso de maduración de la DC y no solo actuar como un activador de la inmunosupresión y también que el DHA, probablemente, actúe a través del monómero RXR del heterodímero PPARγ:RXR en las DCs. / Docosahexaenoic Acid (DHA), an omega-3 PUFA, has been associated with immunosuppressive effects in lymphocytes, monocytes and macrophages, but there were no studies about its effects on dendritic cells (DCs). So human monocytes were differentiated to DCs in presence of growing concentrations of DHA. These cells displayed divergent changes in their phenotypes depending on the maturation stage, downregulating both their lymphoproliferative stimulation capacity and IL-12 and IL-10 secretion levels in mature stage. All these effects were DHA concentration dependent.We performed then similar experiments with other fatty acids: EPA, Linoleic Acid (LA), and Oleic Acid. With EPA and LA the results were similar to that shown by DHA in a qualitative manner but DHA was the most potent fatty acid affecting DC phenotype, lymphoproliferation activation capacity and cytokine secretion.The results obtained with DHA were similar to those obtained in DCs with PPARγ ligands although DHA is considered a poor PPARγ ligand compared to EPA, LA or Rosiglitazone. By the other side, theoretically, the PPARγ heterodimer can be activated both by RXR and PPARγ ligands. 9cRA, an RXR ligand, was tested at low concentrations in DCs. The results obtained were similar in phenotype and lymphoproliferative stimulation capacity to those shown by DHA treatments. However, mature 9cRA treated DCs secreted normally IL-10 with IL-12 inhibited. The simultaneous addition of 9cRA and Rosiglitazone on DCs displayed additive effects on DCs phenotype indicating that 9cRA was probably acting through PPARγ:RXR. When DHA and 9cRA or Rosiglitazone were combined, the phenotypic changes were much more additive for Rosiglitazone with DHA than for 9cRA with DHA. This was strongly suggesting that DHA could act mainly activating RXR in the PPARγ heterodimer.Finally, GW9662, an specific inhibitor of PPARγ, blocked the effects unleashed by DHA, Rosiglitazone and 9cRA. Moreover, GW9662 by himself altered normal maturation phenotype on DCs implying that PPARγ must fulfil a significant role in the DC maturation process moreover than the immunosuppression of the DC response and that DHA, probably, was acting through the RXR monomer of PPARγ heterodimer in DCs.

In this thesis, the morphological changes of the anode surface in lithium sulphur cell, during early cycling, were simulated using symmetrical lithium electrode cells with dissolved polysulphides (PS) in the electrolyte. Electron microscopy (SEM) was used as the principal investigation technique to study and record the morphological changes. The resulting images from the SEM were analysed and discussed. The initial surface structure of the lithium anode largely influenced the ensuing morphological changes taking place through lithium dissolution (pits) and lithium deposition (dendrites) during discharge and charge respectively. The rate of lithium dissolution and deposition was found to be linearly proportional to the current density applied to the cell and the effect of cycling on the anode was proportional to the total charge of the cell in general in agreement with the expected reaction. The effect of self-discharge on the anode was also studied using photoelectron spectroscopy (XPS) in tandem with SEM. The results indicated that self-discharge, occurring in the form of corrosion of the anode SEI by PS reduction, was influenced by the altered morphology of the cell after cycling. The findings presented in this project can be understood as a preliminary description for the morphological changes in the anode and their influence in the performance of lithium sulphur battery, which can be further investigated by more advanced methods. / <p>Joint collaboration project between Scania CV AB and Uppsala University.</p>

MRI has been applied to directly detecting neuronal activity. The direct detection of multiple dendrite sites within the brain offers an important tool in the analysis of the brain for mapping cognition. In this, multiple dendrite contributions can be applied with the same model between the parallel and anti-parallel orientations depending on a spatial depolarization and re-polarization wave. Once the strength of the dendritic contribution was calculated, the spatially dependent phase shifts were theoretically modeled. In the construction of this column the dendrites were modeled as having cylindrical symmetry, uniform current density, and the intracellular current was taken as the primary current contribution to the volume dendrite model. The method examined the system using the known volume density of the dendrites treated with the current dipole model over a voxel. The maximum effect of the field strength, phase, and percent signal change was theoretically calculated. The maximum field was calculated as 1.07 nT, the maximum phase was calculated as 2.14 mrad, and the maximum percent signal increase was calculated as 0.217 %. / Overview of the basics of MRI imaging -- Overview of neural activation and imaging of the activation -- Theory and methods -- Results. / Department of Physics and Astronomy

Thesis (M.S.)--University of Michigan, 1986.

Thesis (M.S.)--University of Michigan, 1986.