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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
501

Genetical and Clinical Studies in Wilson's Disease

Waldenström, Erik January 2007 (has links)
Wilson’s disease is a rare inborn error of metabolism caused by a defect in ATP7B, a protein necessary for proper copper excretion into bile. It is characterised by copper accumulation with hepatic and central nervous system dysfunction. We investigated 24 Swedish families with Wilson’s disease by sequencing the entire coding sequence using a new technique called manifold sequencing. Disease causing mutations were found in 44 out of 48 alleles. From data obtained in the first study, the two most common mutations (C3207A and C2930T) were sought in 2640 anonymous DNA samples from a Swedish population, using a pooling strategy and solid-phase minisequencing. Four C3207A and one C2930T were found. From the number of C3207A, a prevalence of Wilson’s disease in Sweden of about 1 in 110,000 could be estimated. Four groups with three patients each had four different genotypes concerning mutations in ATP7B. The patients’ psychopathological symptoms were investigated, using the Karolinska Scales of Personality rating (KSP) and Comprehensive Psychopathological Rating Scale (CPRS). A trend towards lower CPRS scores was seen in the groups with mutations known to render ATP7B completely without activity. Using 61Cu liver PET in patients homozygous for mutations in ATP7B, heterozygotes, normal individuals and two patients with alcoholic liver cirrhosis, significantly slower uptake was seen in the homozygotes as compared to the heterozygotes and normal individuals. The patients with cirrhosis had values in between. This implies that 61Cu liver PET might be used as an additional rapid and little invasive diagnostic tool in Wilson’s disease. In a retrospectively studied cohort consisting of 363 patients followed in Sweden and the UK, nine cases of aggressive intra-abdominal malignancies were seen, which is more than expected. Caution should be taken in the follow-up of Wilson’s disease patients.
502

Clusterin and Megalin in The Spinal Cord

Wicher, Grzegorz January 2006 (has links)
Nerve injury induces up-regulation of the chaperone protein clusterin in affected neurons and adjacent astrocytes but the functional significance of this response is unclear. We find that motor neuron survival is significantly greater in clusterin(+/+) compared to (-/-) mice. These results suggest that endogenous expression of clusterin is neuroprotective after nerve injury. However, motor neuron survival in clusterin overexpressing mice was not different from that in wildtype mice. In contrast, treatment of neuronal cultures with clusterin-TAT recombinant protein is neuroprotective, including a positive effect on neuronal network complexity. Since extracellular clusterin complexes are endocytosed after binding to various receptors, we examined the expression of known clusterin binding receptors in the spinal cord. We find that megalin is expressed in the nuclei of two cell populations in the mouse spinal cord: i) oligodendrocytes in late postnatal and adult spinal cord white matter, and ii) transiently (E11-15) in a population of immature astrocytes in the dorsal spinal cord. We find no correlation between clusterin and megalin in the intact or injured spinal cord. However, intranuclear localization of megalin, suggesting signalling properties, is supported by the co-localization with γ-secretase, the enzyme responsible for endodomain cleavage of megalin. Megalin deficient mice display a pronounced deformation of the dorsal part of spinal cord, an almost complete absence of oligodendroglial progenitor cells, and a marked reduction in the population of mature astrocytes at later prenatal developmental stages. Taken together, our findings indicate that megalin is a novel signalling molecule for distinct populations of glial cells in the pre- and postnatal spinal cord. The functional role(s) of megalin is unknown. However, its expression patterns and cellular localization suggest that megalin regulates differentiation of oligodendrocytes and astrocytes in the prenatal spinal cord, as well as the function of myelinating oligodendrocytes in the postnatal spinal cord.
503

Functional Consequences of Model Complexity in Hybrid Neural-Microelectronic Systems

Sorensen, Michael Elliott 15 April 2005 (has links)
Hybrid neural-microelectronic systems, systems composed of biological neural networks and neuronal models, have great potential for the treatment of neural injury and disease. The utility of such systems will be ultimately determined by the ability of the engineered component to correctly replicate the function of biological neural networks. These models can take the form of mechanistic models, which reproduce neural function by describing the physiologic mechanisms that produce neural activity, and empirical models, which reproduce neural function through more simplified mathematical expressions. We present our research into the role of model complexity in creating robust and flexible behaviors in hybrid systems. Beginning with a complex mechanistic model of a leech heartbeat interneuron, we create a series of three systematically reduced models that incorporate both mechanistic and empirical components. We then evaluate the robustness of these models to parameter variation, and assess the flexibility of the models activities. The modeling studies are validated by incorporating both mechanistic and semi-empirical models in hybrid systems with a living leech heartbeat interneuron. Our results indicate that model complexity serves to increase both the robustness of the system and the ability of the system to produce flexible outputs.
504

Determine The Effects Of Long Term Playing Soccer On The Degeneration Of Lumbar Spine

Altunsoz, Omur Serdal 01 August 2006 (has links) (PDF)
The main purpose of this study was to determine whether playing soccer at high intensity training for a long period causes degeneration of the lumbar spine or not. This degeneration may occur without any symptoms or low back pain. Results of the present study were discussed in the framework of lumbar disc degeneration, trunk strength, lumbar and hip bone mineral density, trunk flexibility, activity MET scores for active and veteran soccer groups. There have been four subject groups in this study (15 active soccer players, 15 sedentary participants, 14 veteran soccer players, 13 sedentary participants). The BMD was measured in anterior-posterior view with a second-generation dual energy X-ray absorptiometry (DEXA) device. Isokinetic trunk strength data were recorded with the Biodex System Dynamometer (Biobex Medical Inc, Shirly, NY) at the 60&ordm / /sec and 120&ordm / /sec. Plain lateral radiographs were taken. The presence of degenerative changes of each lumbar vertebra was determined by using the Kellgren and Lowrence Score. A modified Schober test was used to measure lumbar flexion. Findings of the study demonstrated that veteran soccer players displayed greater lumbar disc degeneration than other groups. Moreover, v active soccer group had more BMD than other groups, but the veteran group&amp / #8217 / s BMD results were not different while comparing the control participants. Isokinetic test findings of the current study, trunk extension strength at 60/sec was significantly higher in active 1st group players than 2nd group participants, but there were no significant differences between the 1st group and 2nd group in terms of trunk flexion strength and agonist/antagonist ratio at 60/sec. In conclusion, Findings of the study support the main hypothesis that playing soccer at high intensity training at a long period of time may cause lumbar spine degeneration. Degeneration may occur without low back symptoms. Moreover, results supported the idea that Soccer can be accepted an impact loading sport that are to keep or accelerate bone mineral density. At last, having abnormal trunk extension strength while playing actively may cause lumbar disc degeneration on the spine at later years. A similar study should be carried out with a larger number of subjects, and longitudinal studies should be designed to examine the factors that effect the degeneration on the lumbar spine.
505

Effects of hydrodynamic culture on embryonic stem cell differentiation: cardiogenic modulation

Sargent, Carolyn Yeago 07 July 2010 (has links)
Stem and progenitor cells are an attractive cell source for the treatment of degenerative diseases due to their potential to differentiate into multiple cell types and provide large cell yields. Thus far, however, clinical applications have been limited due to inefficient differentiation into desired cell types with sufficient yields for adequate tissue repair and regeneration. The ability to spontaneously aggregate in suspension makes embryonic stem cells (ESCs) amenable to large-scale culture techniques for the production of large yields of differentiating cell spheroids (termed embryoid bodies or EBs); however, the introduction of hydrodynamic conditions may alter differentiation profiles within EBs and should be methodically examined. The work presented here employs a novel, laboratory-scale hydrodynamic culture model to systematically interrogate the effects of ESC culture hydrodynamics on cardiomyocyte differentiation through the modulation of a developmentally-relevant signaling pathway. The fluidic environment was defined using computational fluid dynamic modeling, and the effects of hydrodynamic conditions on EB formation, morphology and structure were assessed. Additionally, EB differentiation was examined through gene and protein expression, and indicated that hydrodynamic conditions modulate differentiation patterns, particularly cardiogenic lineage development. This work illustrates that mixing conditions can modulate common signaling pathways active in ESC differentiation and suggests that differentiation may be regulated via bioprocessing parameters and bioreactor design.
506

Strategies of neuroprotection in an in vivo model of retinal degeneration induced by mitochondrial dysfunction

Rojas-Martinez, Julio Cesar 16 October 2012 (has links)
Current approaches to treat neurodegenerative disease provide only mild symptomatic relief but do not modify the natural history of these conditions. A large body of evidence suggests that mitochondrial dysfunction is a key event in the pathophysiology of neurodegeneration. Supporting and improving mitochondrial function has a big potential as a strategy for neuroprotection. The goal of this dissertation was to test whether interventions that target mitochondrial function are effective at preventing neurodegeneration induced by mitochondrial failure in vivo. A rodent model of optic neuropathy induced by the mitochondrial toxin rotenone was used to test the neuroprotective effects of methylene blue (MB) and near-infrared light (NIL), two interventions with mechanisms of action localized to mitochondria. This work also tested the effects of memantine, an NMDA receptor blocker, to further characterize the relationship between excitotoxicity and mitochondrial dysfunction. Neuroprotective effects were evaluated via behavioral testing of visual function and histopathological analysis of the retina. The neurochemical effects of MB, NIL and memantine were analyzed in vitro and in vivo with indicators of oxidative stress, cell respiration and catalytic activity of respiratory enzymes, including NADH dehydrogenase and cytochrome oxidase. MB, a diaminophenothiazine with potent antioxidant and unique redox properties, prevented the changes in visual function and the retinal histopathology induced by rotenone. In vitro, MB increased oxygen consumption and prevented the increases in oxidative stress in brain tissue induced by rotenone. NIL prevented the behavioral impairment and the decrease in retinal and visual pathway metabolic activity, retinal nerve fiber layer thickness and ganglion cell layer cell density induced by rotenone in a dose-dependent manner. Whole-brain cytochrome oxidase and superoxide dismutase activities were also increased in NIL-treated subjects in a dose-dependent manner, suggesting an in vivo transcranial effect of NIL. Finally, uncompetitive NMDA receptor blockade with memantine displayed neuroprotection against rotenone-induced neurodegeneration in a dose-response manner, and this effect was associated with a decrease in retinal oxidative stress and a long-term increase in neuronal energy metabolism capacity. These data constitute a proof-of-principle that interventions that target the mitochondria and support the function of the respiratory chain are effective at preventing neurodegeneration in vivo. / text
507

Bothnia dystrophy, a clinical, genetical and electrophysiological study

Burstedt, Marie January 2003 (has links)
A high frequency of retinitis pigmentosa (RP) is found in Northern Sweden. In an inventory of autosomal recessive RP patients in Västerbotten County, a great number of cases with a unique phenotype was noticed, denoted Bothnia Dystrophy (BD). The aim of the study was to describe the phenotype, to determine the chromosomal location, and to identify the gene. Patients typically show night blindness from early childhood. Symptoms of defect macular function with a decrease of visual acuity can appear in early adulthood. The retinal fundus shows irregular white spots in a central, and parafoveal pattern along the arcades. Centrally areolar maculopathy develops and round circular atrophies are observed in the periphery. The disease was shown to be associated with a missense mutation in the RLBP1 gene resulting in an amino acid substitution (R234W) in the cellular retinaldehyde-binding protein (CRALBP). The R234W mutation was found in a homozygous state in 61 patients affected with BD. Ten patients were heterozygous for the R234W mutation, and presented a similar phenotype. No additional mutations in the coding sequence or exon-intron junctions were found. CRALBP is localised in retinal pigment epithelium (RPE), and Müller cells of the retina. In the RPE, CRALBP functions as a carrier protein for endogenous retinoids. Dark adaptometry and electrophysiologic testing showed an initial loss of rod function followed by a progressive reduction of the cone responses in older ages. A compromised rod function, dysfunction of the Müller cells, and indications of a disturbed function of the inner retina were found. With prolonged dark adaptation, a gradual increase in retinal sensitivity to light and an improvement of the ERG components occurred. The findings indicate a prolonged synthesis of photopigments, retardation of the visual process in the retinal pigment epithelium and a loss of retinal cells probably starting at a relative early age in BD. To evaluate the subjective visual function in BD patients, a battery of objective tests of visual function and composite score of the 25-item NEI-Visual Function Questionnaire (VFQ-25) were analyzed. We found that weighted distance logMAR visual acuity (WVA), had the strongest association with subjective visual function, and that there was a considerable loss of subjective and objective visual function with increasing age in BD patients. The prevalence of BD is as high as 1:3600 in Västerbotten County. The possibility that recycling of retinoids localized in the RPE might be impaired in BD might give future therapeutic possibilities. Due to the large and clinically well-characterized set of patients with this disease, they constitute a suitable study group.
508

Processing and exploration of CT images for the assessment of aortic valve bioprostheses

Wang, Qian 09 December 2013 (has links) (PDF)
The aim of the study was to assess the feasibility of CT based 3D analysis of degenerated aortic bioprostheses to make easier their morphological assessment. This could be helpful during regular follow-up and for case selection, improved planning and mapping of valve-in-valve procedure. The challenge was represented by leaflets enhancement because of highly noised CT images. Contrast-enhanced ECG-gated CT scan was performed in patients with degenerated aortic bioprostheses before reoperation (in-vivo images). Different methods for noise reduction were tested and proposed. 3D reconstruction of bioprostheses components was achieved using stick based region segmentation methods. After reoperation, segmentation methods were applied to CT images of the explanted prostheses (exvivo images). Noise reduction obtained by improved stick filter showed best results in terms of signal to noise ratio comparing to anisotropic diffusion filters. All segmentation methods applied to the best phase of in-vivo images allowed 3D bioprosthetic leaflets reconstruction. Explanted bioprostheses CT images were also processed and used as reference. Qualitative analysis revealed a good concordance between the in-vivo images and the bioprostheses alterations. Results from different methods were compared by means of volumetric criteria and discussed. A first approach for spatiotemporal visualization of 3D+T images of valve bioprosthesis has been proposed. Volume rendering and motion compensation techniques were applied to visualize different phases of CT data. Native valve was also considered. ECG-gated CT images of aortic bioprostheses need a preprocessing to reduce noise and artifacts in order to enhance prosthetic leaflets. Stick based methods seems to provide an interesting approach for the morphological characterization of degenerated bioprostheses.
509

Classification of Genotype and Age by Spatial Aspects of RPE Cell Morphology

Boring, Michael 12 August 2014 (has links)
Age related macular degeneration (AMD) is a public health concern in an aging society. The retinal pigment epithelium (RPE) layer of the eye is a principal site of pathogenesis for AMD. Morphological characteristics of the cells in the RPE layer can be used to discriminate age and disease status of individuals. In this thesis three genotypes of mice of various ages are used to study the predictive abilities of these characteristics. The disease state is represented by two mutant genotypes and the healthy state by the wild-type. Classification analysis is applied to the RPE morphology from the different spatial regions of the RPE layer. Variable reduction is accomplished by principal component analysis (PCA) and classification analysis by the k-nearest neighbor (k-NN) algorithm. In this way the differential ability of the spatial regions to predict age and disease status by cellular variables is explored.
510

Amžinės geltonosios dėmės degeneracijos ir išeminės širdies ligos sąsajos su matrikso metaloproteinazių genų polimorfizmu / Age-related macular degeneration and ischemic heart disease associations with matrix metalloproteinasesgenes polymorphism

Liutkevičienė, Rasa 20 December 2011 (has links)
Darbo uždaviniai: 1. Nustatyti pradinės AGDD paplitimą vidutinio amžiaus (40 – 64 metų) pacientų, sergančių IŠL grupėje bei atsitiktinėje to paties amžiaus Kauno miesto gyventojų imtyje. 2. Palyginti pacientų, sergančių tik IŠL ir IŠL bei pradinės AGDD klinikinius duomenis. 3. Nustatyti MMP-2 (-735 C/T), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T) genotipų dažnį bei genotipų derinių įtaką AGDD susiformavimui. 4. Nustatyti MMP-2 (-735 C/T), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T) genotipų dažnį esant minkštoms ir kietoms drūzoms, sergant AGDD. 5. Nustatyti MMP-2 (-735 C/T), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T) genotipų dažnį bei genotipų derinių įtaką AGDD ir IŠL drauge bei tik IŠL pasireiškimui. 6. Nustatyti funkcinio kontrastinio jautrumo tyrimo rodmenis pacientams, sergantiems pradine lengva ir pradine vidutine AGDD bei spalvų juslės pokyčius sergantiems pradine AGDD, ir oftalmologiškai sveikiems pacientams. / The goals were as follows: 1. To determine the prevalence of AMD in patients with IHD and compare with the prevalence in a random sample of Kaunas population (at 40-64 yrs old). 2. To compare the main clinical characteristics of the patients exhibiting early AMD and IHD together with the patients with IHD alone. 3. To determine the frequency of the genotypes of the matrix metalloproteinases (MMP-2 (-735 C/T), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T)), and genotype combinations that have an influence on the development of early AMD. 4. To determine the frequency of the genotypes of the matrix metallo¬proteinases (MMP-2 (-735 C/T), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T)), in early AMD patients with soft or hard drusen. 5. To determine the frequency of the genotypes of the matrix metallo¬proteinases (MMP-2 (-735 C/T), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T)), and the influence of genotype combi¬na¬tions on the development of AMD and IHD together, and only on IHD development. 6. To determine the results of functional acuity contrast sensitivity test in patients with early mild and early intermediate AMD, and color contrast sensitivity in patients with AMD, and in ophthalmologically healthy patients.

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