Dissertations / Theses on the topic 'Musculoskeletal system Medical genetics'

Medial tibial stress syndrome (MTSS) is a stress and overuse injury that presents as pain on the medial aspect of the lower two-thirds of the tibia. It is most often caused by repetitive actions on hard surfaces such as running, marching, and dancing. Individuals most affected by MTSS are runners, members of the military, dancers, and athletes that play soccer, volleyball and basketball. While MTSS has a relatively standard presentation of pain on the medial aspect of the tibia, it can occasionally be mistaken for other injuries such as stress fractures or compartment syndrome. If a diagnosis is unsure, methods such as x-ray, bone-scan, and MRI can be utilized to better obtain the correct diagnosis. A variety of treatments exist for MTSS including, ice, massage, muscle strengthening, and rest. A combination of these various techniques is most often what is employed. In this study, the effectiveness of a set of resistance ankle exercises in combination with ice and massage was tested and compared to that of ice and massage alone. The hypothesis was that athletes receiving the exercises as part of their treatment, in addition to the icing and massaging, would have a greater decrease in pain from MTSS than athletes just receiving ice and massage as treatment. The exercises would strengthen the muscles of the lower leg that, when weak, can contribute to the development of MTSS. Results indicated that the exercises yielded a more significant decrease in pain from MTSS than ice and massage alone.

Over the past several decades and increasingly in recent years, blood transfusions in the United States have plummeted as surgery has gotten more precise and less invasive. Alongside this decrease in general transfusions has been an increase in specific blood products for patients whose immune systems require special treatment. Simultaneously, trends in healthcare in the United States have incentivized regional hospitals to join large conglomerates. These coexisting factors have left regional blood banks, traditionally economically viable, in much weakened states. This thesis was born out of an initial curiosity to discover whether or not genetic science, and genotyping in particular, could benefit small regional blood banks by allowing them to bring down their costs of pre-transfusion blood testing or offer new products. I focus on the San Diego Blood Bank (SDBB) as a case study of the larger blood banking industry. In the course of this research, economic factors were taken into consideration as well as social and health. A minor question that was also discussed was whether genotyping not only help regional blood banks survive fiscally but also open the gateway to better patient outcomes and lower costs nationally of blood transfusions and their associated costs. Feasibility analyses and financial modeling suggest support for genotyping blood donors and transfusion recipients in order to more perfectly match blood transfusions through extended antigen matching.

Human Artificial Chromosomes (HACs) have been confirmed as viable gene expression vectors and a potential tool for gene therapy. However, standard lipid-based delivery methods pose a developmental barrier. The work presented in this thesis includes the development of a novel and efficient HAC vector system for gene delivery into human cells using Herpes Simplex Virus-1 (HSV-1) amplicon technology. The development of HSV-1 amplicons for HAC delivery is a major step forward in the HAC field. In this study, utilising the technology allowed the generation of HACs at a high efficiency in a range of human cell types, which is a significant step in the development for HAC gene expression systems. Further work also showed a significant difference in HAC stability between cell lines. Real-time PCR analysis determined that Aurora B was over expressed in cell lines in which the HACs were unstable. This correlated with high levels of chromosomal instability and was confirmed by western blot analysis. Since Aurora B is a kinase involved in at least two cell cycle checkpoints, cellular phosphorylation levels were perturbed to mimic that observed in the unstable cells, using okadaic acid, which is both a protein phosphatase inhibitor and activates Aurora B. Treatment of cells showed an increase in both HAC and overall chromosomal instability and an increase in histone H3 Serine 10 and Serine 28 phosphorylation. The project also focussed on the development of a gene expression system using HSV-1 amplicons. Two different strategies were explored. Firstly, one approach involved engineering the HPRT genomic locus into an HSV-HAC vector, by Red mediated recombination for complementing the HPRT deficiency in HPRT- HT1080 cells. As an alternative approach, co-infection of two different HSV-1 HAC amplicons for generating a single HAC gene vector was investigated. Initial experiments utilising the latter approach were the most successful and show promise for generating HAC containing genes via this strategy.

The opioid receptors and their endogenous ligands have long been implicated in a variety of traits including addiction, impulsive behaviors and substance dependence. Using phenotypic measurements collected from the IASPSAD, data from a latent class analysis and data from a SNP array and additional genotyping assays, association and regression tests were performed to determine the effects of common SNPs encoded in the genes of the opioid receptors and ligands on various traits relating to alcohol dependence. Although only one SNP can be reported as significant for substance dependence within alcoholics, there were a few results approaching significance that may offer some insight into variation within alcoholism.

Understanding the impact of epigenetic mechanisms on tumorigenesis is essential, as epigenetic alterations are associated with tumor initiation and progression. Because epigenetic changes are reversible, they are potential targets for cancer therapy. Nucleosome Remodeling Factor (NURF) is a chromatin-remodeling complex that regulates gene expression by changing nucleosome positioning along the DNA sequence. Previous studies have shown a role for NURF in embryonic development as well as regulating genes involved in tumor progression. In this work we investigated the impact of eliminating NURF function in tumorigenesis in vivo. BALB/c mice challenged with syngeneic 67NR breast cancer cell lines, injected into the mammary fat pad, lacking NURF, due to knockdown of its essential subunits Bptf, showed reduction in tumor growth comparing to control tumors. The observed reduction in tumor growth was abrogated in immunodeficient mice lacking a functional immune system. Bptf KD and control 67NR cells grew at similar rates in vitro. Similar findings were observed in our lab using 66cl4 breast cancer cell lines. Using immunofluorescence staining, no significant difference in CD8+, CD4+, NK and MDSC cells infiltrations into the tumor microenvironment was observed in 66cl4 tumors. Preliminary results from 67NR tumors suggested more CD4+ and CD8+ cells. Gene expression profile of tumor tissues from BALB/c mice injected with 67NR and 66cl4 cell lines showed enrichment of genes associated with immune response. Our findings suggested a role of the immune system in targeting tumor cells lacking Bptf in vivo.

All peripheral sensory information is represented in the thalamus before being transmitted to the cortex, with the exception of olfaction. The thalamus projects to all areas of the neocortex and all neocortical areas project to the thalamus. I am interested in the development of three corticothalamic populations which are anatomically and functionally distinct; they project to different thalamic nuclei and generate different post-synaptic responses. Layer V fibres project exclusively to higher order thalamic nuclei. These projections drive thalamic neuron activity and mediate a trans-thalamic cortico-cortical relay. Layer VI and VIb fibres project to both first order and higher order thalamic nuclei. These projections modulate thalamic neuron activity and mediate feedback to the thalamus. Using three transgenic mouse lines I demonstrate that developing corticothalamic fibres target the specific groups of thalamic nuclei to which they project in adulthood. Rbp4-Cre::tdTomato labels layer V; Ntsr1-Cre::tdTomato labels layer VI; Golli-τ-eGFP labels layer VI and VIb. By P4 layer V fibres arborise densely in higher order nuclei but do not innervate the first order nuclei at any age. In contrast, at this age VI and VIb fibres densely innervate the first order ventral posterior-medial nucleus (VPM), as well as higher order nuclei. Layer VI and VIb fibres accumulate outside the dorsal Lateral Geniculate Nucleus (dLGN) from P2 before entering at P6. During this waiting period, retinal fibres transmit spontaneous waves of activity to the dLGN. To assess whether retinal input regulates corticothalamic circuit development I performed monocular enucleation. I demonstrate that after loss of retinal input, layer VI and VIb fibres enter the dLGN prematurely, by P2. Furthermore layer V fibres which target the retino-recipient superior colliculus also enter prematurely following enucleation. These results suggest there may be a retinal mechanism which regulates the timing of corticofugal ingrowth to joint retinal/cortical targets. The loss of retinal driver input to the dLGN also induces layer V driver fibres to aberrantly enter the first order dLGN. These results are the first to show cross-hierarchical rewiring after losing peripheral sensory input. The role of peripheral activity in the developing nervous system is underscored by activity dependent molecular mechanisms. I therefore performed a microarray gene expression experiment to systematically analyse molecular changes in the dLGN following enucleation. The expression of numerous genes is altered following enucleation including potassium channels Kcnk9 and Kcnn3, kinase pathway mediators, Shc3 and Dgkk, and immediate early genes BDNF, Egr1 and Egr2. The majority of genes regulated by enucleation are regulated in the opposite direction over development indicating that the loss of the retinal input delays maturation of the dLGN transcriptome. In this thesis I demonstrate that early corticothalamic development targets specific thalamic nuclei. Using the visual system as a model I demonstrate that retinal input regulates corticothalamic development and contributes to the transcriptome of thalamic nuclei.

Mitochondrial diseases encompass a broad range of devastating disorders that typically affect tissues with high-energy requirements. These disorders have been difficult to diagnose and research because of the complexity of mitochondrial genetics, and the large variability seen among patient populations. We have devised and carried out a mechanistic study to generate a cell based model for Leigh’s disease caused by mitochondrial DNA mutation 8993 T>G. Leigh’s disease is a multi-organ system disorder that depends heavily on the mutation burden seen within various tissues. Using new reprogramming and sequencing technologies, we were able to show that Leigh’s disease patient fibroblasts reprogrammed to induced pluripotent stem cells maintain the same level of mutation burden seen in the original patient cell line. Mutation burden was maintained through several passages and spontaneous differentiation. This cell based model could be useful for future pathogenesis studies, or therapeutic drug screenings in a patient and tissue specific manner.

INTRODUCTION: Cerebral Palsy (CP) is a sensorimotor disorder characterized by dysfunctional motor coordination, balance problems, and loss of selective motor control. Motor coordination exhibited as co-contraction, has been subjectively quantified using gait analysis, but recent studies have begun to objectively analyze the amount of co-contraction by collecting electromyography (EMG) data. Center of pressure excursion (COPE) measurements collected during a single leg standing test (SLST) have shown to be more valid measurements of balance in populations with motor disabilities than a SLST alone. A recent study has correlated increased COPE velocity with a lower fall risk as determined by reported fall frequency, suggesting a more objective measure of fall risk. The current study aimed to determine if the fall risk calculated by COPE velocity in children with CP is correlated with co-contraction index value in various muscle synergy groups. It was hypothesized that i) co-contraction index values will differ between high and low fall risk groups, ii) there will be preferential activation of different synergy groups within the high and low fall risk groups, and iii) there will be a negative and direct correlation between COPE velocity and co-contraction index values for all synergy groups. METHODS: Fall risk grouping was determined by average COPE velocity values calculated from previously reported fall frequency groups. Balance ability was determined by COPE measurements during a SLST on a force plate. Muscle synergy groups were determined by common muscle pairings at the hip, knee and ankle. Co-contraction indices were determined from linear envelopes plotted from muscle group EMG data. An independent t-test was run on muscle synergy groups between high and low fall risk groups. Nonparametric Analysis of Variance (ANOVA) and Tukey post-hoc tests were run on the high and low fall risk groups separately to determine differences in co-contraction index value within high and low fall risk groups. A Pearson correlation analyzed COPE velocity and co-contraction index value. RESULTS: No significant differences in muscle synergy between the high and low fall risk groups were found (p = 0.476, 0.076, 0.064, 0.364). The ANOVA and Tukey post-hoc tests for high fall risk group found significant differences in co-activation index value between the sagittal hip and frontal hip groups (p = 0.022) and sagittal hip and ankle groups (p = 0.016). Low fall risk group was found to have significant differences between the sagittal hip and frontal hip groups (p = 0.038) and frontal hip and knee groups (p = 0.012). Weak and negative correlations were found between COPE velocity and both knee and ankle groups (r = -0.309, -0.323, p = 0.059, 0.050). Negligible and insignificant correlations were found between frontal hip and sagittal hip synergies and COPE velocity ((r = 0.013, -0.068, p = 0.475, 0.367). CONCLUSION: There is insufficient evidence to claim that muscle group activations are different depending on fall risk grouped by COPE velocity. It is not currently possible to correlate COPE velocity to a specific synergy group recruitment. However, data do suggest that sagittal hip and knee strategies are recruited more than ankle and frontal hip strategies during SLST.

Huntington’s disease is an incurable, progressive neurological disorder characterized by loss of motor control, psychiatric dysfunction, and eventual dystonia leading to death. Despite the fact that this disorder is caused by a mutation in one single gene, there is no cure. The mutant Huntingtin (mHtt) protein is expressed ubiquitously throughout the brain but frank cell death is limited to the striatum. Recent work has suggested that Rhes, Ras homolog enriched in striatum, which is selectively expressed in the striatum, may play a role in Huntington’s disease neuropathology. In vitro studies have shown Rhes to be an E3 ligase for the post-translational modification protein SUMO. Rhes increases binding of SUMO to mHtt which competes for the same binding site as Ubiquitin. SUMOylation of mHtt leads to disaggregation and cellular death, whereas ubiquitination leads to aggregation and cellular protection. In a previous study we showed that deletion of Rhes caused a decrease in the Huntington’s disease phenotype in mice. We hypothesized that mice lacking Rhes would also show increased aggregation in the striatum and this increased aggregation would correlate in a rescue of behavioral symptoms. Despite the prior in vitro and in vivo evidence, deletion of Rhes in vivo did not alter the aggregation of mHtt in the striatum of mice however deletion of Rhes still showed a rescue from the diseased phenotype. This result would indicate that deletion of Rhes alters the neurobehavioral phenotype of Huntington’s disease through a different pathway than promoting aggregation in striatal cells.

Dwarfism is considered one of the most recognized congenital defects of animals and humans and can be hereditary or sporadic in cause and expression. There are two general morphologic categories within this vastly diverse disease. These categories are disproportionate and proportionate dwarfism and within each of these there are numerous phenotypes which have been extensively described in humans, and to a lesser extent in dogs, cattle, mice, chickens, and other domestic species. Ponies and Miniature horses largely differ from full size horses only by their stature. Ponies are often defined as those whose height is not greater than 14.2 hands; however the maximum height for Miniature horses is constitutionally defined as 8.2 hands. Dwarfism is not considered a desirable genetic trait for Miniature horses. A majority of these conformationally inferior horses showed consistent physical abnormalities typical of disproportionate dwarfisms as seen in other mammal species. A whole genome scan with the Illumina Equine SNP50 chip clearly implicated a region on ECA1 as being associated with dwarfism of horses. The region implicated on the horse chromosome 1 (Equus Caballus; ECA1) contained a candidate gene for dwarfism, aggrecan (ACAN). Mutations were found in Exons 2, 6, 11 and 15 with each mutation associated with a distinct type of dwarfism. These mutations are independently transmitted throughout the population. Absence of normal homozygotes for these mutations and absence of normal horses which were heterozygous for these mutations indicated that these alleles caused dwarfism in those genotypes. These genotypes did not explain all observed dwarves in this population.

Development of safe and efficient approaches for gene delivery in human embryonic stem cells (hESc) and particularly in human induced pluripotent stem (hiPS) cells, which can be derived in a person-specific manner, is considered to be imperative for harnessing their full potential in both the basic and applied research. The aim of this study was to evaluate the potential of human artificial chromosome (HAC) for gene delivery and expression in hESc and hiPS cells. HAC offers many potential advantages including the provision for carrying large genes with corresponding regulatory elements to obtain long-term regulated gene expression. In addition, they can replicate and segregate independently without integration into the host cell genome. To develop HAC in hiPS cells, the first part of the study was aimed at generating hiPS cells utilising the Herpes Simplex Virus (HSV)-1 amplicon system. With the use of EBNA-1/OriP retention elements incorporated into the HSV-1 amplicon vectors, hiPS cells completely free of vector and transgenes sequences were successfully derived from human embryonic fibroblasts. The hiPS cells exhibited proliferation and differentiation potential similar to that of hESc. In the second part of the study, development of HAC in hESc and hiPS cells was assessed by utilising the HSV-1 amplicon system to deliver the HAC DNA. Analysis of the hESc confirmed the presence of functional HAC which replicated the behaviour of the host chromosomes. Additionally, HAC generation did not lead to impairment in the developmental potential and pluripotency of hESc. The hiPS cells supported HAC at low frequency but DNA also integrated into the host chromosomes. The HAC system, therefore, needs further refinements to improve the frequency of HAC formation and reduce the chromosomal integration of HAC constructs in hiPS cells. Overall, these findings provide a simple and safe way of pluripotency induction and genetic modification of pluripotent stem cells using the HSV-1 amplicon system and represent an important advance towards patient specific gene and cell therapy.

Hypertension, or high blood pressure (BP), is an ever-growing epidemic in the developing world. Understanding the genetics behind essential hypertension (EH), or hypertension with no known cause, is especially important. In this study, three single nucleotide polymorphisms (SNPs) known to be linked to an increase in susceptibility to EH were quantified from a cohort of Kenyans living in the Kasigau region. The SNPs are located in three genes that are part of the renin angiotensin system, the primary regulatory pathway in humans controlling BP. They include: AGT (rs699), AGTR1 (rs5186), and HSD11β2 (rs5479). Overall, by using a fluorescent-based RT-PCR technique, the genotype distribution of AGT (rs699) was 0.63 C/C, 0.34 C/T, and 0.03 T/T. When evaluated as normotensive, prehypertensive, Stage I, or Stage II categories the allele frequencies for f(C)= 0.77,0.85,0.81, 0.77, respectively, and demonstrated Hardy Weinberg Equilibrium (HWE) as assessed by Χ2, p < 0.05. The genotype distribution of AGTR1 (rs5186) was 0.96 A/A, 0.03 A/C, and 0.00 C/C and the genotype distribution of HSD11β2 (rs5479) was 0.46 A/A, 0.46 A/C, and 0.08 C/C. The majority of genotype frequencies for each SNP were in HWE, with the exception of the AGT (rs699) SNP found in the sublocation of Bughuta suggesting other evolutionary selective pressures may be at work in this subpopulation. The high prevalence of the susceptible C allele for AGT (rs699) likely implies it is a critical factor in the high prevalence of EH observed in this population.

Functional vasodilation in arterioles is impaired with chronic ischemia. We sought to examine the impact of chronic ischemia and age on skeletal muscle resistance artery function. To examine the impact of chronic ischemia, the femoral artery was resected from young (2-3mo) and adult (6-7mo) mice and the profunda femoris artery diameter was measured at rest and following gracilis muscle contraction 14 days later using intravital microscopy. Functional vasodilation was significantly impaired in ischemic mice (14.4±4.6% vs. 137.8±14.3%, p<0.0001 n=8) and non-ischemic adult mice (103.0±9.4% vs. 137.8±14.3%, p=0.05 n=10). In order to analyze the cellular mechanisms of the impairment, a protocol was developed to apply pharmacological agents to the experimental preparation while maintaining tissue homeostasis. Endothelial and smooth muscle dependent vasodilation were impaired with ischemia, 39.6 ± 13.6% vs. 80.5 ± 11.4% and 43.0 ± 11.7% vs. 85.1 ± 10.5%, respectively. From this data, it can be supported that smooth muscle dysfunction is the reason for the observed impairment in arterial vasodilation.

Frontotemporal dementia (FTD) is the second most common early-onset dementia. A rare mutation in CHMP2B gene was found to be associated with FTD linked to chromosome 3. Previous studies have shown that mutant CHMP2B could lead to impaired autophagy pathway and altered RNA metabolism. However, it is still unknown what genes mediate the crosstalk between different pathways affected by mutant CHMP2B. Genetic screens designed to identify genes interacting with mutant CHMP2B represents a key approach in solving the puzzle. Expression of mutant CHMP2B (CHMP2Bintron5) in Drosophila eyes leads to a neurodegenerative phenotype including melanin deposition and disrupted internal structure of ommatidia. The phenotype is easily quantified by estimating the percentage of black dots on the surface of the eyes. Using this established Drosophila model, I searched for genes encoding RNA binding proteins that genetically modify CHMP2Bintron5 toxicity. I found that partial loss of Pumilio, a translation repressor, mitigates CHMP2Bintron5 induced toxicity in the fly eyes. Western blot analysis showed that down regulation of Pumilio does not significantly decrease CHMP2Bintron5 protein level, indicating indirect regulation involved in suppression of the phenotype. The molecular targets regulated by Pumilio and the mechanism underlying CHMP2Bintron5 toxicity suppression by Pumilio down-regulation requires further investigation.

Frontotemporal dementia (FTD) is the second most common early-onset dementia. A rare mutation in CHMP2B gene was found to be associated with FTD linked to chromosome 3. Previous studies have shown that mutant CHMP2B could lead to impaired autophagy pathway and altered RNA metabolism. However, it is still unknown what genes mediate the crosstalk between different pathways affected by mutant CHMP2B. Genetic screens designed to identify genes interacting with mutant CHMP2B represents a key approach in solving the puzzle. Expression of mutant CHMP2B (CHMP2Bintron5) in Drosophila eyes leads to a neurodegenerative phenotype including melanin deposition and disrupted internal structure of ommatidia. The phenotype is easily quantified by estimating the percentage of black dots on the surface of the eyes. Using this established Drosophila model, I searched for genes encoding RNA binding proteins that genetically modify CHMP2Bintron5 toxicity. I found that partial loss of Pumilio, a translation repressor, mitigates CHMP2Bintron5 induced toxicity in the fly eyes. Western blot analysis showed that down regulation of Pumilio does not significantly decrease CHMP2Bintron5 protein level, indicating indirect regulation involved in suppression of the phenotype. The molecular targets regulated by Pumilio and the mechanism underlying CHMP2Bintron5 toxicity suppression by Pumilio down-regulation requires further investigation.

Genomic instability, in the form of gene mutations, insertions/deletions, and gene amplifications, is one of the hallmarks in many types of cancers and other inheritable genetic disorders. Trinucleotide repeat (TNR) disorders, such as Huntington’s disease (HD) and Myotonic dystrophy (DM) can be inherited and repeats may be extended through subsequent generations. However, it is not clear how the CAG repeats expand through generations in HD. Two possible repeat expansion mechanisms include: 1) polymerase mediated repeat extension; 2) persistent TNR hairpin structure formation persisting in the genome resulting in expansion after subsequent cell division. Recent in vitro studies suggested that a family A translesion polymerase, polymerase θ (Polθ), was able to synthesize DNA larger than the template DNA. Clinical and in vivo studies showed either overexpression or knock down of Polθ caused poor survival in breast cancer patients and genomic instability. However, the role of Polθ in TNR expansion remains unelucidated. Therefore, we hypothesize that Polθ can directly cause TNR expansion during DNA synthesis. The investigation of the functional properties of Polθ during DNA replication and TNR synthesis will provide insight for the mechanism of TNR expansion through generations.

Purpose: The purpose of this study was to evaluate the effectiveness of triaging patients with motion-provoked dizziness into a benign paroxysmal positional vertigo (BPPV) clinic. Method: A retrospective chart review was performed of veterans who were tested and treated for BPPV in a triaged BPPV clinic and veterans who were tested and treated for BPPV in a traditional vestibular clinic. Results: The BPPV triage clinic had a hit rate of 39%. On average, the triaged BPPV clinic reduced patient wait times by 23 days relative to the wait times for the traditional vestibular clinic while also reducing patient costs. Conclusion: Triaging patients with BPPV is one method to improve access to evaluation and treatment and a mechanism for the effective use of clinic time and resources.

Background & Aims: Despite advances in surgical care and chemotherapeutic regimens, the five-year survival rate for Stage IV Hepatoblastoma (HB), the predominant pediatric liver tumor, remains at 27%. YAP1 and β-Catenin co-activation occurs in 80% of children’s HB; however, a lack of conditional genetic models precludes exploration of tumor maintenance and therapeutic targets. Thus, the clinical need for a targeted therapy remains unmet. Given the predominance of YAP1 and β-catenin activation in children’s tumors, I sought to evaluate YAP1 as a therapeutic target in HB. Approach & Results: Herein, I engineered the first conditional murine model of HB using hydrodynamic injection to deliver transposon plasmids encoding inducible YAP1S127A, constitutive β-CateninDelN90, and a luciferase reporter to murine liver. Tumor regression was evaluated using in vivo bioluminescent imaging, and tumor landscape characterized using RNA sequencing, ATAC sequencing and DNA foot-printing. Here I show that YAP1 withdrawal in mice mediates >90% tumor regression with survival for 230+ days. Mechanistically, YAP1 withdrawal promotes apoptosis in a subset of tumor cells and in remaining cells induces a cell fate switch driving therapeutic differentiation of HB tumors into Ki-67 negative “hbHep cells.” hbHep cells have hepatocyte-like morphology and partially restored mature hepatocyte gene expression. YAP1 withdrawal drives formation of hbHeps by modulating liver differentiation transcription factor (TF) occupancy. Indeed, tumor-derived hbHeps, consistent with their reprogrammed transcriptional landscape, regain partial hepatocyte function and can rescue liver damage in mice. Conclusions: YAP1 withdrawal, without modulation of oncogenic β-Catenin, significantly regresses hepatoblastoma, providing the first in vivo data to support YAP1 as a therapeutic target for HB. Modulating YAP1 expression alone is sufficient to drive long-term regression in hepatoblastoma because it promotes cell death in a subset of tumor cells and modulates transcription factor occupancy to reverse the fate of residual tumor cells to mimic functional hepatocytes.

Viruses are known to be associated with 20% of human cancers. Epstein Barr virus (EBV) in particular is the first virus associated with human cancers. Here, we computationally detect EBV and explore the effects of this virus across cancers by taking advantage of the fact that EBV microRNAs (miRNAs) and Epstein Barr virus small RNAs (EBERs) are expressed at all viral latencies. We identify and characterize two sub-populations of EBV positive tumors: those with high levels of EBV miRNA and EBERS expression and those with medium levels of expression. Based on principal component analysis (PCA) and hierarchical clustering of viral miRNAs across all samples we observe a pattern of expression for these EBV miRNAs which is correlated with both the tumor cell type (B cell versus epithelial cell) and with the overall levels of expression of these miRNAs. We further investigated the effect of the levels of EBV miRNAs with the overall survival of patients across cancers. Through Kaplan Meier survival analysis we observe a significant correlation with levels of EBV miRNAs and lower survival in adult AML patients. We also designed a machine learning model for risk assessment of EBV in association with adult AML and other clinical factors. Our next aim was to identify targets of EBV miRNAs, hence, we used a combination of previously known methodologies for miRNA target detection in addition to a multivariable regression approach to identify targets of these viral miRNAs in stomach cancer. Finally, we investigate the variations across EBV subtype specific EBNA3C gene which interacts with the host immune system. Preliminary data suggests potential regional variations plus higher pathogenicity of subtype 1 in comparison to subtype 2 EBV. Overall, these studies further our understanding of how EBV manipulates the tumor microenvironment across cancer subtypes.

Traumatic brain injury (TBI) is a leading cause of disability worldwide. Annually, 150 to 200/1,000,000 people become disabled as a result of brain trauma. Axonal degeneration is a critical, early event following TBI of all severities but whether axon degeneration is a driver of TBI remains unclear. Molecular pathways underlying the pathology of TBI have not been defined and there is no efficacious treatment for TBI. Despite this significant societal impact, surprisingly little is known about the molecular mechanisms that actively drive axon degeneration in any context and particularly following TBI. Although severe brain injury may cause immediate disruption of axons (primary axotomy), it is now recognized that the most frequent form of traumatic axonal injury (TAI) is mediated by a cascade of events that ultimately result in secondary axonal disconnection (secondary axotomy) within hours to days. Proposed mechanisms include immediate post-traumatic cytoskeletal destabilization as a direct result of mechanical breakage of microtubules, as well as catastrophic local calcium dysregulation resulting in microtubule depolymerization, impaired axonal transport, unmitigated accumulation of cargoes, local axonal swelling, and finally disconnection. The portion of the axon that is distal to the axotomy site remains initially morphologically intact. However, it undergoes sudden rapid fragmentation along its full distal length ~72 h after the original axotomy, a process termed Wallerian degeneration. Remarkably, mice mutant for the Wallerian degeneration slow (Wlds) protein exhibit ~tenfold (for 2–3 weeks) suppressed Wallerian degeneration. Yet, pharmacological replication of the Wlds mechanism has proven difficult. Further, no one has studied whether Wlds protects from TAI. Lastly, owing to Wlds presumed gain-of-function and its absence in wild-type animals, direct evidence in support of a putative endogenous axon death signaling pathway is lacking, which is critical to identify original treatment targets and the development of viable therapeutic approaches. Novel insight into the pathophysiology of Wallerian degeneration was gained by the discovery that mutant Drosophila flies lacking dSarm (sterile a/Armadillo/Toll-Interleukin receptor homology domain protein) cell-autonomously recapitulated the Wlds phenotype. The pro-degenerative function of the dSarm gene (and its mouse homolog Sarm1) is widespread in mammals as shown by in vitro protection of superior cervical ganglion, dorsal root ganglion, and cortical neuron axons, as well as remarkable in-vivo long-term survival (>2 weeks) of transected sciatic mouse Sarm1 null axons. Although the molecular mechanism of function remains to be clarified, its discovery provides direct evidence that Sarm1 is the first endogenous gene required for Wallerian degeneration, driving a highly conserved genetic axon death program. The central goals of this thesis were to determine (1) whether post-traumatic axonal integrity is preserved in mice lacking Sarm1, and (2) whether loss of Sarm1 is associated with improved functional outcome after TBI. I show that mice lacking the mouse Toll receptor adaptor Sarm1 gene demonstrate multiple improved TBI-associated phenotypes after injury in a closed-head mild TBI model. Sarm1-/- mice developed fewer beta amyloid precursor protein (βAPP) aggregates in axons of the corpus callosum after TBI as compared to Sarm1+/+ mice. Furthermore, mice lacking Sarm1 had reduced plasma concentrations of the phosphorylated axonal neurofilament subunit H, indicating that axonal integrity is maintained after TBI. Strikingly, whereas wild type mice exhibited a number of behavioral deficits after TBI, I observed a strong, early preservation of neurological function in Sarm1-/- animals. Finally, using in vivo proton magnetic resonance spectroscopy, I found tissue signatures consistent with substantially preserved neuronal energy metabolism in Sarm1-/- mice compared to controls immediately following TBI. My results indicate that the Sarm1-mediated prodegenerative pathway promotes pathogenesis in TBI and suggest that anti-Sarm1 therapeutics are a viable approach for preserving neurological function after TBI.

碩士
中原大學
資訊工程研究所
98
Illustration for medical visualization can achieve the hand-drawn effects or enhance some geometric features such as muscle texture. Illustrative visualization as text illustration provides realistic or enhanced 3D images to achieve better teaching effects than medical volume visualization for residents or students with less clinic experiences. Our methods provide illustration method for the musculoskeletal surgery. Because the relations between operated and neighboring structures, and dissected muscles and skins can be demonstrated, the simulations can be an effective tool for teaching residents and students and rehearsing surgery for surgeons.

碩士
國立中正大學
勞工關係學系暨研究所
102
Hospital porters are vulnerable to various degrees of musculoskeletal injuries from delivering patients and the transferring objects because of their excessive lumbar loadings or fatigability which may arise from overuse of muscles, repetitive woks, and inappropriate postures. In addition, the hospital porters may also suffer from mental or physical fatigue, muscle aches for example, because of their moving around most of the time. Results of investigations from United States, European Union, and Taiwan have indicated that occupational musculoskeletal discomfort accounts a lot for labor insurance payment and the proportion is getting increasingly higher. However, there were limited studies on hospital porters’ work-related musculoskeletal discomforts. The purpose of this study is to evaluate characteristics and risk factors of hospital porters’ musculoskeletal discomforts by the Nordic Musculoskeletal Questionnaire (NMQ). This study will recruit 84 hospital porters from a medical system in middle Taiwan, 73 of them from a medical center and 11 of them from a regional hospital, for face-to-face interview to increase response rate and accuracy. Fifty seven percent (57.56%) of hospital porters mentioned discomfort on various parts of body. The largest percentage, 73 (83.91%) people, mentioned discomfort in lower back, followed by 69 (79.31%) people with discomfort in right knee, and 68 (78.16%) in left shoulders. It is about 90.80 percents which are thought caused by all or partial work. Chi-square test, multi-logistic regression and multiple regression are used to analyze the uncomfortable part of muscle and skeleton.

Mestrado em Ciências da Fisioterapia
Background: Association Football is associated with high incidence of injuries that could affect both players and clubs in terms of cost for health and performance. Aims: Analyse injury characteristics, prevalence, incidence, and identify associated Risk Factors for musculoskeletal injuries in a youth Football Academy during one season, using both Medical Attention (MAI) and Time-loss injury (TLI) definitions. Methods: Descriptive epidemiological study with a prospective, cohort design that followed the recommendations of the F-MARC’s Consensus Statement on Injury Definitions and Data Collection Procedures in Studies of Football (Soccer) Injuries. Sample formed by 19 young footballers (17.05±0.52 years). Results: MAI prevalence was 94.74% (8.16 Injuries/Player) and TLI prevalence was 63.16% (1.58 Injuries/Player). MAI Total II was 44.54 Injuries/1000EH. Match II was more than six times higher than training’s. For TLI, Total II was 8.62 Injuries/1000EH. II was up to almost seven times higher in matches than training. Three quarters of injuries occurred in the lower limbs. MAI were most seen in the Lower Leg / Achilles Tendon, Knee and Thigh. TLI mainly affected the Thigh and Ankle. Haematoma / Contusion (MAI: 44.50%; TLI: 26.67%), Muscle (MAI: 22.60%; TLI: 23.33%) and Joint injuries (MAI: 12.90%; TLI: 16.67%) were the most common diagnosis. More than two thirds of injuries were traumatic and around 20% were due to Foul Play. Rate of recurrence was 10.97% (MAI) and 23.33% (TLI). Total Injury Burden was 211.77 Days of absence/1000EH, and was more than five times higher for matches than for training. Match injuries were more and more severe. Conclusions: Risk of injury was high throughout the season, with 18 out of 19 players sustaining at least one injury. High exposure to the physical and mental demands of football may predispose players to injury. Development of fair play and injury prevention strategies should be emphasized by coaching and medical staffs.
RESUMO: Enquadramento: O Futebol é associado a elevada incidência de lesões, que podem implicar custos para a saúde e performance de atletas e clubes. Objetivos: Analisar as características da lesão, prevalência, incidência, e identificar Fatores de Risco para lesões músculo-esqueléticas numa Academia de jovens futebolistas durante uma época, usando as definições de lesão “Medical Attention” (MAI) e “Time-loss” (TLI). Metodologia: Estudo epidemiológico descritivo, de desenho prospetivo em coorte que seguiu as recomendações do Consensus Statement on Injury Definitions and Data Collection Procedures in Studies of Football (Soccer) Injuries da F-MARC. Amostra constituída por 19 jovens futebolistas (17,05±0,52 anos). Resultados: A prevalência das MAI foi 94,74% (8,16 Lesões/Jogador) e das TLI foi 63,16% (1,58 Lesões/Jogador). A Incidência de Lesão Total (ILT) das MAI foi 44,54 Lesões/1000HE. A Incidência de Lesão em Jogos (ILJ) foi seis vezes maior que em treino (ILTr). Para as TLI, a ILT foi 8,62 Lesões/1000HE. A ILJ foi até sete vezes maior que a ILTr. Três quartos das lesões ocorreram nos membros inferiores. As MAI afetaram a Perna / Tendão de Aquiles, Joelho e Coxa. As TLI afetaram principalmente a Coxa e o Tornozelo. Hematoma / Contusão (MAI: 44,50%; TLI: 26,67%), lesão Muscular (MAI: 22,60%; TLI: 23,33%) e lesão Articular (MAI: 12,90%; TLI: 16,67%) foram os diagnósticos mais comuns. Mais de dois terços das lesões foram traumáticas e cerca de 20% deveram-se a Foul Play. A Taxa de Recidiva foi de 10,97% (MAI) e 23,33% (TLI). O Injury Burden Total foi 211,77 Dias de Ausência/1000HE, e foi pelo menos cinco vezes mais elevado em jogos que em treino. Lesões em jogo foram mais numerosas e mais graves. Conclusões: O risco de lesão foi elevado durante a época, com 18 em 19 jogadores a sofrer pelo menos uma lesão. Elevada exposição às exigências físicas e mentais do futebol podem predispor o jogador para lesão. Estratégias de fair play e prevenção de lesões devem ser enfatizadas pelas equipas técnica e médica.

Indiana University-Purdue University Indianapolis (IUPUI)
Symptoms of post-traumatic stress disorder (PTSD) are a common comorbidity in veterans seeking treatment of chronic musculoskeletal pain (CMP). However, little is known regarding the mutual influence of PTSD and CMP in this population. Using cross-sectional and longitudinal data from a randomized clinical trial evaluating a stepped care intervention for CMP in Iraq/Afghanistan veterans (ESCAPE), this dissertation examined the relationships between PTSD and CMP along with other factors including depression, anxiety, catastrophizing and health-related quality of life. The Classification and Regression Tree (CART) analysis was conducted to identify key factors associated with baseline PTSD besides CMP severity. A series of statistical analyses including logistical regression analysis, mixed model repeated measure analysis, confirmatory factor analysis and cross-lagged panel analysis via structural equation modeling were conducted to test five competing models of PTSD symptom clusters, and to examine the mutual influences of PTSD symptom clusters and CMP outcomes. Results showed baseline pain intensity and pain disability predicted PTSD at 9 months. And baseline PTSD predicted improvement of pain disability at 9 months. Moreover, direct relationships were found between PTSD and the disability component of CMP, and indirect relationships were found between PTSD, CMP and CMP components (intensity and disability) mediated by depression, anxiety and pain catastrophizing. Finally, the coexistence of PTSD and more severe pain was associated with worse SF-36 Physical Component Summary (PCS) and Mental Component Summary (MCS) scores. Together these findings provided empirical support for the mutual maintenance theory.

Fused in sarcoma (FUS) is an RNA binding protein involved in DNA repair and RNA metabolism, including mRNA transcription, splicing, transport and translation. FUS is genetically and pathologically associated with rare and aggressive forms of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). To explore the mechanisms by which pathogenic mutations in FUS cause neurodegeneration in ALS-FUS, we generated a series of FUS knock-in mouse lines that express the equivalent of the ALS-associated mutant proteins FUSP525L and FUSΔEX14 at physiological levels from the FUS locus. We demonstrate that heterozygous mutant FUS mice show progressive, age-dependent loss of vulnerable subpopulations of spinal motor neurons. While ALS-associated mutations in FUS lead to partial loss of function, we provide genetic evidence that the motor neuron phenotype observed is a consequence of a dose-dependent gain of function, associated with the insolubility of FUS and related RNA binding proteins (RBPs). Furthermore, we show that motor neuron degeneration is driven by cell autonomous mechanisms, associated with mutant FUS-independent inflammatory changes. In this faithful mouse model of ALS-FUS, we demonstrate that an antisense oligonucleotide (ASO) targeting the FUS transcript (ION363) results in the efficient silencing of both wild type and mutant FUS alleles, and that postnatal reduction of FUS protein levels in the brain and spinal cord delays disease onset in this mouse model of ALS-FUS. In a first-in-human trial of ION363, we demonstrate that repeated, intrathecal injections of this candidate therapeutic in an ALS patient with a FUSP525L mutation leads to the efficient silencing of both wild type and mutant FUS in the central nervous system, and a reduction in the burden of FUS aggregates that are a pathological hallmark of ALS-FUS. In mouse genetic and human clinical studies, we provide evidence in support of a therapeutic strategy by which silencing of the FUS gene may be used to prevent or delay disease onset in pre-symptomatic carriers of pathogenic FUS mutations, or to slow disease progression in symptomatic ALS- and FTD-FUS patients. In addition, we use this newly generated model to investigate the role of potential modifiers of FUS toxicity, including hnRNP U and UPF1, and study the role of chronic neuroinflammation in the disease progression that could lead to the development of novel therapeutics to provide immediate clinical benefit to patients with ALS-FUS.

No
Triple-negative breast cancers (TNBC) are clinically heterogeneous, an aggressive form of breast cancer with poor diagnosis and highly therapeutic resistant. It is urgently needed for identifying novel biomarkers with increased sensitivity and specificity for early detection and personalised therapeutic intervention. Microarray profiling offered significant advances in molecular classification but sample scarcity and cohort heterogeneity remains challenging areas. Here, we investigated diagnostics signatures derived from human triple-negative tissue. We applied REMARK criteria for the selection of relevant studies and compared the signatures gene lists directly as well as assessed their classification performance in predicting diagnosis using leave-one-out cross-validation. The cross-validation results shows excellent classification accuracy ratios using all data sets. A subset signature (17-gene) extracted from the convergence of eligible signatures have also achieved excellent classification accuracy of 89.37% across all data sets. We also applied gene ontology functional enrichment analysis to extract potentially biological process, pathways and network involved in TNBC disease progression. Through functional analysis, we recognized that these independent signatures have displayed commonalities in functional pathways of cell signaling, which play important role in the development and progression of TNBC. We have also identified five unique TNBC pathways genes (SYNCRIP, NFIB, RGS4, UGCG, LOX and NNMT), which could be important for therapeutic interventions as indicated by their close association with known drivers of TNBC and previously published experimental studies.
Yorkshire Cancer Research for the Supplementary ort of CWS (BPP049 and B209PG)

Obesity studies using humans are confounded by variables that are difficult to control and are restricted by ethical considerations. Given that they display many of the common attributes of obese humans, animal models of obesity have become invaluable tools for studying the etiology and related pathologies of the obese condition. Obese animals have been often reported to exhibit marked reductions in skeletal muscle size, but currently available data on the contractile function of skeletal muscles in rodent models of obesity are scarce and often conflicting. Therefore, the overall aim of this study was to further knowledge and understanding of the functional status of skeletal muscle in ob/ob mouse, a commonly used model of obesity, by employing a combination of biochemical and physiological methods and whole muscle and single fibre approaches. The animals were used at an age where there is no evidence of hyperglycemia or hypertension, thereby allowing the study of obesity without the often concurrent syndromes of diabetes and hypertension. The muscles examined included two hind limb muscles [extensor digitorum longus (EDL) – predominately locomotor; soleus (SOL) – predominately postural) and one trunk muscle [sternomastoid (SM) – involved in head/neck motion and respiratory assistance]. The data generated in the series of studies comprising this work is summarised as follows: 1. The EDL, SM and SOL muscles of ob/ob mice and controls were examined with respect to size [mass, muscle mass-to-body mass ratio, cross-sectional area (CSA)], fibre CSA, protein content, myosin heavy chain (MHC) content, MHC isoform composition and fibre type composition. Compared with the controls, all three muscles from ob/ob mice were smaller in size, with EDL and SM being the most affected. The CSA values for fibres from the predominant fibre types in EDL and SM muscles (IIB and IIB+IID) were smaller than those for fibres from control muscles, and the fibre size differences were consistent with the differences in muscle size. No differences between EDL, SM and SOL muscles from ob/ob and lean mice were found with respect to total protein content and MHC content (both normalised to muscle mass). Electrophoretic analyses of MHC isoform composition in whole muscle homogenates and single muscle fibres showed a shift towards slower MHC isoforms and a greater proportion of hybrid fibres in all three muscles of ob/ob mice, which suggest that skeletal muscles of ob/ob mice may follow a different pattern of development or undergo an obesity-related structural remodeling which does not involve changes in protein content (Chapter 3). 2. Isometric contractile characteristics [twitch and tetanic force-generating capacity and kinetics; force-frequency relationship] of EDL, SM and SOL muscles from ob/ob and lean mice were explored using an isolated whole muscle preparation. The following statistically significant differences were observed for muscles from ob/ob mice when compared to muscles from lean mice: (i) lower force-generating capacity (Po/body mass) for EDL, SM and SOL muscles; (ii) slower kinetics of the twitch response (W50 value) for EDL and SOL muscles; (iii) lower rate of force development of the tetanic response for EDL muscle; (iv) slower relaxation kinetics of the tetanic response for EDL and SOL muscles; (v) a leftward shift in the force-frequency relationship for EDL and SOL muscles. (Chapter 4). 3. The possibility that skeletal muscles of ob/ob mice displayed slower relaxation kinetics because of functional alterations in the contractile apparatus and/or SR function was explored using a single fibre approach. In these experiments, the following parameters were probed in mechanically skinned type IIB fibres (the predominant fibre type in both muscle groups) from EDL muscles of ob/ob and lean mice: (i) Ca2+ sensitivity (pCa50; pCa10; Hill coefficient: where pCa = -log10[Ca2+]); (ii) endogenous SR Ca2+ content; (iii) SR Ca2+ leak rate; (iv) maximal SR Ca2+ loading capacity at two different [Ca2+] (an indicator of slow/fast SR properties); and, (v) maximal SR Ca2+ loading at pCa 7.3, normalised to maximum Ca2+-activated force (an indicator of the density of SR Ca2+ pumps in the fibre). The data showed similarities in all the parameters except (v), suggesting that EDL type IIB fibres from ob/ob mice possess a lower density of the SR Ca2+ pumps per fibre volume. A lower density of SR Ca2+ pumps would reduce the ability of the SR to sequester Ca2+ and return [Ca2+]i back to resting levels following a contractile response, thereby slowing relaxation. (Chapter 5). 4. The fatigability characteristics [fatigue resistance; recovery of peak tetanic force at 5 min and 60 min after cessation of fatiguing exercise; loss in the ability to generate force at stimulation frequencies of 5 to 90 (or 110) Hz, at 60 min after cessation of fatiguing exercise] of EDL, SM and SOL muscles from ob/ob and lean mice were explored using isolated whole muscle preparations and a fatiguing protocol that elicited a state of low frequency fatigue in all three muscles. As fatigability of the muscle is determined, in part, by the rate of energy supply relative to the rate of energy consumption, ob/ob and lean mice were also compared with respect to myofibrillar ATPase activity (determined in EDL type IIB fibres – the predominant fibre type) and lactate dehydrogenase (LDH) isoenzyme profile (determined in EDL, SM and SOL muscle homogenates). Musclespecific decreases in fatigability were observed in muscles from ob/ob mice, with: (i) EDL displaying greater fatigue resistance; (ii) EDL exhibiting greater recovery of peak tetanic force at 5 min post-fatiguing exercise; (iii) EDL and SOL displaying greater recovery of force at 60 min post-fatiguing exercise; and (iv) EDL and SOL exhibiting a lower loss in the ability to generate force at low stimulation frequencies (greater than or equal to 30 Hz). The decreased fatigability of EDL muscles from ob/ob mice could not be related to lower myofibrillar ATPase activity in type IIB fibres. No simple relationship could be established between the fatigability characteristics of EDL, SM and SOL muscles of ob/ob mice and their LDH isoenzyme profile. This is because the LDH isoenzyme data showed a shift towards a more aerobic-oxidative phenotype for all three muscles of ob/ob mice, including SM which showed no changes in fatigability characteristics. (Chapter 6). The data collected on EDL, SM and SOL muscles from lean mice revealed a number of notable inter-muscle differences in these animals: (i) SOL contains a larger proportion of hybrid fibres than EDL and SM (Chapter 3); (ii) SM has a lower force-generating capacity, as indicated by (peak tetanic force)/(estimated physiological cross-sectional area), than EDL and SOL (Chapter 4); (iii) SM displays faster contractile kinetics than EDL and produces a different force-frequency curve (Chapter 4); and (iv) compared with SOL muscle, EDL and SM display a markedly greater loss of ability to develop force when stimulated at higher stimulation frequencies (greather than or equal to 50 Hz) at 60 min recovery from fatiguing exercise (Chapter 6). As EDL and SM muscles contain similar fibre type composition, their differences in contractile characteristics must be related to other factors, such as (but not limited to) differences in anatomical location and physiological function.

Indiana University-Purdue University Indianapolis (IUPUI)
Neurofibromatosis type 1 is a genetic disease that results from either heritable or spontaneous autosomal dominant mutations in the NF1 gene, which encodes a protein serving, at least in part, to accelerate the intrinsic hydrolysis of active Ras-GTP to inactive Ras-GDP. A second-hit NF1 mutation precedes predominant NF1 neoplasms, including juvenile myelomoncytic leukemia (JMML) and plexiform neurofibroma formation, potentially fatal conditions with no medical therapy. While NF1 loss of heterozygosity (LOH) in myeloid progenitor cells sufficiently engenders leukemogenesis, plexiform neurofibroma formation depends on LOH in Schwann cells and Nf1 heterozygosity in the hematopoietic system. Specifically, recruited Nf1+/- mast cells accelerate tumorigenesis through secreted cytokines and growth factors. Nf1+/- mast cells depend upon deregulated signaling in c-kit pathways, a receptor system conserved in hematopoietic stem cells (HSCs). Accordingly, Nf1-/- myeloid progenitor cells, which can induce a JMML-like disease in mice, also demonstrate deregulated c-kit receptor signaling. C-kit-activated Nf1+/- mast cells and Nf1-/- myeloid progenitors both show increased latency and potency of active Erk1 and Erk2, the principal cytosolic-to-nuclear effectors of canonical Ras-Raf-Mek signaling. Thus, Erk represents a potential regulator of leukemogenesis and tumor-associated inflammation. However, single and combined Erk1 and Erk2 roles in HSC function, myelopoiesis, and mature mast cell physiology remain unknown, and recent hematopoietic studies relying on chemical Mek-Erk inhibitors have produced conflicting results. Here, we show that hematopoietic stability, myelopoiesis, and mast cell generation require Erk1 or Erk2, but individual isoforms are largely dispensable. Principally, Erk-disrupted hematopoietic stem cells incorporate BrdU but are incapable of dividing, a novel and cell type-specific Erk function. Similarly, mast cell proliferation requires Erk but cytokine production proceeds through other pathways, elucidating molecule-specific functions within the c-kit cascade. Based on these findings, we have reduced tumor mast cell infiltration by treating genetically-engineered tumor model mice with PD0325901, a preclinical Mek-Erk inhibitor. Moreover, we have devised a quadruple transgenic HSC transplantation model to examine dual Erk disruption in the context of Nf1 nullizygosity, testing whether diseased hematopoiesis requires Erk. These insights illuminate cell-specific Erk functions in normal and Nf1-deficient hematopoiesis, informing the feasibility of targeting Mek-Erk in NF1-associated disease.

La reconnaissance du pluralisme du système de santé, et donc des interdépendances unissant l’État aux acteurs participant à l’offre des services de santé, pose non seulement la question de la capacité de l’État à gouverner selon ses objectifs, mais aussi celle de la forme des interventions entreprises à cette fin. Cette thèse vise à comprendre comment se développe la participation de l’État à la gouverne d’un secteur de services de santé, et plus particulièrement comment ses interactions avec les acteurs impliqués dans l’offre des services affectent, au fil du temps, les possibilités d’actions étatiques sous-jacentes à la sélection d’instruments de gouverne spécifiques. Elle propose pour ce faire un modèle théorique qui s’inspire de la littérature traitant des instruments de gouverne ainsi que de la théorie de la pratique (Bourdieu). La participation de l’État à la gouverne y est conçue comme le résultat d’un processus historique évolutif, marqué alternativement par des périodes de stabilité et de changement en regard des instruments mobilisés, qui se succèdent selon l’articulation des interactions et des contextes affectant les possibilités d’action que les acteurs perçoivent avoir. Ce modèle a été appliqué dans le cadre d’une étude de cas portant sur le secteur génétique québécois (1969-2010). Cette étude a impliqué l’analyse processuelle et interprétative de données provenant de sources documentaires et d’entrevues réalisées auprès de représentants du ministère de la Santé et des Services sociaux ainsi que de médecins et chercheurs œuvrant dans le secteur de la génétique. Ces analyses font émerger quatre périodes de stabilité en regard des instruments de gouverne mobilisés, entrecoupées de périodes de transition au cours desquelles le Ministère opère une hybridation entre les instruments jusque là employés et les nouvelles modalités d’intervention envisagées. Ces résultats révèlent également que l’efficacité de ces instruments - c’est-à-dire la convergence entre les résultats attendus et produits par ceux-ci - perçue par le Ministère constitue un facteur de première importance au regard de la stabilisation et du changement des modalités de sa participation à la gouverne de ce secteur. En effet, lorsque les instruments mobilisés conduisent les médecins et chercheurs composant le secteur de la génétique à agir et interagir de manière à répondre aux attentes du Ministère, les interventions ministérielles tendent à se stabiliser autour de certains patterns de gouverne. À l’inverse, le Ministère tend à modifier ses modes d’intervention lorsque ses interactions avec ces médecins et chercheurs le conduisent à remettre en cause l’efficacité de ces patterns. On note cependant que ces changements sont étroitement liés à une évolution particulière du contexte, amenant une modification des possibilités d’action dont disposent les acteurs. Ces résultats révèlent enfin certaines conditions permettant au Ministère de rencontrer ses objectifs concernant la gouverne du secteur de la génétique. Les instruments qui impliquent fortement les médecins et chercheurs et qui s’appuient sur des expertises qu’ils considèrent légitimes semblent plus susceptibles d’amener ces derniers à agir dans le sens des objectifs ministériels. L’utilisation de tels instruments suppose néanmoins que le Ministère reconnaisse sa propre dépendance vis-à-vis de ces médecins et chercheurs.
The recognition of a pluralistic healthcare system based on the interdependency between the State and other healthcare providers raises the question on how the State can manage according its own goals and what are the necessary actions to achieve those. The current thesis aims at understanding how can the State participate in governing the healthcare sector. More precisely, it intends to accurately look at how the State’s interaction with several health care providers impacts over time its action capacities to select specific governance instruments. To achieve these objectives, the thesis uses a theoretical framework based on literature about governance instruments as well as Bourdieu’s practice theory. The State’s participation in governance is conceived as an evolving historical process with periods of stability and change over instruments in use. They alternate according the interaction dynamic and the context influencing an actor’s perception of action possibilities. This framework is applied on a case study: Quebec’s genetic sector (1969-2010). This study involves processes and interpretative analysis of data originating from bibliographical sources and interviews conducted amongst representatives of the Ministère de la Santé et des Services Sociaux (hereafter: the ministry), as well as physicians and researchers working in genetics. The analysis outlines four periods of stability in regards to the mobilization of governance instruments, intertwined by periods of transition during which the ministry operates hybridization between instruments used and new intervention modes considered. These results show that the efficiency of these instruments – meaning the convergence between expected results and actual outcomes – perceived by the ministry is a prime factor in terms of stabilization and change in its participation in the governance of the field. Thus, when used instruments lead physicians and researchers in genetics to act and interact in a way responding to the ministry expectations, its interventions tend to gravitate towards a certain governance pattern. On the other hand, the ministry tends to modify its methods of intervention when its interactions with the physicians and researchers shed doubts on the efficiency of those patterns. It was noticed that these changes are closely linked to a particular evolution of the context, bringing a modification to possible actions available to actors. Finally, results show certain factors allowing the ministry to achieve its objectives in regards to the governance of the genetics sector. The instruments strongly involving physicians and researchers and based on expertise considered to be legitimate appear more likely to bring a favorable action from those specialists in the view of the ministry’s objectives. Nevertheless, using such instruments supposes that the ministry recognizes its own dependence towards these physicians and researchers.