Hepatic ischaemia-reperfusion injury occurs when patients undergoing liver operations such as liver transplantation, tumour resection and shock. Intravenous and intrathecal administration of morphine can be used to provide analgesia prior or after liver surgery. It has been reported that systemically administered morphine conferred protective effect on numerous organs, including heart, brain and kidney. The focus of my research is to investigate the effect of intravenous and intrathecal morphine preconditioning on normal and cirrhotic livers. Further, PI3K/Akt, STAT3 and HO-1/iNOS pathways had been shown to ameliorate hepatic ischemia-reperfusion injury. Hence, we aim to investigate these possible signaling pathways associated with morphine mediated hepato-protection. A partial hepatic ischaemia reperfusion injury model in rats was used. The experiments were divided into two series: one involved in normal livers and the other one involved in cirrhotic livers. For the normal livers, morphine at different doses were administrated intravenously or intrathecally prior the onset of ischaemia, and the experiments were repeated with previous intravenous administration of naloxone methiodide (opioid receptor antagonist), or wortmannin (Akt inhibitor), respectively. For the cirrhotic livers, morphine at optimal doses were injected intravenously or intrathecally prior the onset of ischaemia. Those rats with only induced hepatic ischaemia-reperfusion injury only were marked as control groups. The effect of morphine preconditioning on hepatic architecture, apoptosis and liver function were evaluated respectively by hematoxylin-eosin (H&E) staining, Terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) staining, the expression of cleaved Caspase-3, and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Meanwhile, the expression of phosphorylated Akt, phosphorylated JAK2, phosphorylated STAT3, HO-1 and iNOS were detected by Western Blot to determine the signaling pathways involved by intravenous and intrathecal morphine preconditioning. The normal livers series presented intravenous and intrathecal morphine preconditioning at the 100μg/kg, 10μg/kg, respectively, better persevered hepatic architecture when compared with control groups. The degree of liver cell apoptosis and expression of cleaved caspase-3 were also reduced by intravenous and intrathecal morphine preconditioning. In additional, intravenous and intrathecal morphine preconditioning ameliorated hepatocellular damage by reducing ALT&AST release. Moreover, the expressions of phosphorylated Akt and its downstream protein STAT3 were significantly increased by intravenous and intrathecal morphine preconditioning, compared with their respective control groups. The hepato-protective effect of intravenous and intrathecal morphine preconditioning was reversed by naloxone methiodide or wortmannin pretreatment. The similar pattern of protection was observed in cirrhotic livers. Both intravenous and intrathecal morphine preconditioning protected hepatic architecture much better than control groups. They also attenuated hepatic apoptosis degree and hepatocellular enzyme release. Furthermore, the expression of HO-1 was up-regulated, whereas the expression of iNOS was down-regulated by intravenous and intrathecal morphine preconditioning. In summary, this study provided evidence that intravenous and intrathecal morphine preconditioning could attenuate hepatic ischaemia-reperfusion injury in normal and cirrhotic livers. The involvement of opioid receptors, Akt/STAT3 pathway and HO-1 pathway might be the underlying mechanisms of morphine hepato-protection. Finally, the protective effect of morphine preconditioning might provide a potential therapeutic approach for clinical usage. / published_or_final_version / Anaesthesiology / Master / Master of Philosophy

Spinal cord injury is a devastating source of suffering in the spectrum of human pathophysiology; advancement for clinical therapy in this area has been stagnant in comparison to modern medical development. Current treatments are palliative, and functional recovery is minimal. During the first two weeks after injury, dense glial scar forms that is impenetrable by regenerating axons. Intervention is imperative to minimize scar formation and provide a supportive environment for axonal regeneration. Oligodendrocytes are critical to maintain the health of growing axons during development and after injury. Obtaining these cells through differentiation of neural progenitor cells (NPCs) is a viable option, but current clinical trials involving stem cells are plagued by poor cell survival and undirected differentiation. Research indicates that local extracellular matrix (ECM) is vital to progenitor differentiation and tissue regeneration. During development, spinal cord ECM is comprised of high concentrations of laminin and hyaluronic acid (HA), which provide essential cues to direct NPC migration and differentiation. The purpose of this research is to create a biomaterial optimized to direct NPC differentiation to oligodendrocytes. Natural biomaterials were optimized from distinct combinations of collagen I, HA, and laminin I to model the native ECM signals found during oligodendrocyte maturation. Four material combinations (collagen, collagen-HA-laminin, collagen-HA, and collagen-laminin) were fabricated into injectable hydrogels to mimic the range of compressive and shear mechanical properties present in neonatal central nervous system (CNS) tissue. Differentiation was assessed by culturing rodent fetal NPCs in these materials without specific soluble factors to direct cellular behavior. The three-component hydrogel performed optimally and achieved a 66% oligodendrocyte differentiation rate compared to approximately 15% in the collagen alone hydrogel. An in vivo study was then conducted using a rat contusion model of spinal cord injury with intervention using the injectable, three-component hydrogel seeded with rat NPCs. Functional recovery was assessed using six behavioral tests. Significant recovery was observed using two behavioral tests six weeks post-treatment. Lesion size was measured and correlated well with behavioral outcomes. The data obtained in this research indicate that a multi-component hydrogel mimicking native, developmental CNS tissue may address problems associated with current clinical practice. / text

Abstract Purpose: To characterize physical activity of people using manual wheelchairs with spinal cord injury in Manitoba. Methods: An observational study of manual wheelchairs users with spinal cord injury. Participants completed surveys related to self-efficacy for exercise, physical activity participation, and shoulder pain. Accelerometers were worn for 7 days on the wrist and trunk (GT3X, 100 Hz, 5 s epochs) and completed an activity log concurrently. Individual specific thresholds were determined for moderate intensity during a pace graded wheeling trial. Physical activity and sedentary time were characterized using various derived variables. Results: Twenty five participants (12 tetra:13 para, 21M:4F) demonstrated excellent accelerometer adherence achieving an average of 6.2 days worn for over 13 hours per day. A total of 74.6 min (all activity) and 115 min (contiguous bouts of activity) were achieved over time worn (6.2 days), corresponding to 11.8 and 18.5 min/day respectively. The participants substantially exceeded the published SCI guidelines (40 min/week, P<0.01) but were under the able bodied threshold of 150 min/week (P<0.01). No relationships were observed between surveys and objectively measured PA. Characterization of PA bouts revealed few participants (n=7) exhibiting single bout durations greater than 10 minutes, with an average contiguous bout duration of 30 s. A new functional classification scheme revealed positive correlations to PA variables and wheeling performance. Sedentary times ranged from 6.25 to 8.4 hours per day depending upon accelerometer placement. Conclusion: Arm based accelerometry can be used to determine PA and sedentary characteristics of manual wheelchair users with individual specific moderate intensity thresholds. Participants exceeded the SCI specific activity guidelines in terms of time per week, and failed to reach bout durations of 20 min. This study supports the use of able-bodied PA guidelines as a target. A new functional classification scheme was derived based upon wheeling dependent muscle innervation that had enhanced prediction of PA relative to standard anatomical classification / October 2015

This thesis aims to examine how hindbrain spinal projection neurons (SPNs), namely RoV3, MiV1 and MiV2 control tail undulations during turning behaviors. I find that phototaxic turns differ from forward swims by an increased tail bend and a prolonged cycle period during the first undulation, while the later undulations are largely identical. Interestingly, laser ablation of RoV3, MiV1 and MiV2 neurons specifically affects the first undulation cycle by reducing the tail bend and the cycle period. Thus fish without the SPNs mainly perform forward swims in response to the turn-inducing phototaxic cues. These results suggest that the descending motor command that generates turns in larval zebrafish are composed of two pathways: one generates symmetric tail undulations, and the other, mediated by RoV3, MiV1 and MiV2 neurons, provides a brief and biased effect that modulates the first cycle of tail movement. Furthermore, fish whose unilateral SPNs are ablated are unable to perform turns toward the ablated side during the phototaxis, the optomotor response, the dark-flash response, and spontaneous swims, indicating the universal role of the SPNs in controlling visually-induced and spontaneous turns. Simultaneous two-photon calcium imaging and motor nerve recording in paralyzed fish show that RoV3, MiV2 and most MiV1 neurons on the turning side are active during turns, and that these activities are linearly correlated to the vigor of the intended turns. However, some MiV1 neurons are broadly tuned for all swimming directions. Computer simulations suggest that unilateral descending innervations to a specific type of spinal interneurons, namely commissural inhibitory interneurons, can generate a two-fold increase in the spinal network’s cycle period. This suggests that the SPNs could potentially innervate two types of spinal interneurons, namely \(CoBL_{gly}\) and CoLo, in order to control the rhythm during turns. An additional chapter of this thesis examines the ontogeny of operant and classical learning behaviors in zebrafish. Using strategically positioned visual cues paired with electroshocks, I find that both learning behaviors are expressed reliably around week 3, and reach adult performance levels at week 6. These memories are behaviorally expressed in adults for 6 hours and retrievable for 12 hours.

Individuals with spinal cord injury (SCI) demonstrate reduced limb blood flow and muscle spasticity. It is plausible that the accumulation of metabolites, resulting from reduced perfusion, could exacerbate spasticity via activation of fusimotor neurons by Group III and IV afferents. PURPOSE: To determine the association between peripheral blood flow and muscle spasticity in persons with SCI. METHODS: A total of 16 individuals with SCI were classified into high (N=6), low (N=5), and no (N=5) spasticity groups according to their spasticity levels indicated by the modified Ashworth scale scores. Blood flow was measured in femoral and brachial arteries using duplex Doppler ultrasound and was normalized to limb lean mass obtained with dual energy X-ray absorptiometry. RESULTS: There were no significant group differences in age (30.5±4.15, 38.48±4.61, 32.6±4.89 years), time post SCI (8.5±4.2, 12.6±4.74, 6.8±1.66 years), American SCI Association motor scores (39.2±7.78, 59±12.34, 53.4±1.08), or sensory scores (96±22.1, 144.4±13.97, 130±13.8). Femoral artery blood flow, adjusted for limb lean mass, was significantly different (p=0.002) across the three leg spasticity groups (high 76.03±6.44, low 95.12±15.49, no 142.53±10.86 ml/min/kg).Total leg muscle spasticity scores were significantly and negatively correlated with femoral artery blood flow (r=-0.60, p=0.014). There was no significant difference in brachial artery blood flow between the three groups, indicating that the reduction in blood flow was confined to injured limbs and not due to systemic cardiovascular disorder. CONCLUSION: Among SCI patients, whole-leg blood flow is progressively lower in individuals with greater spasticity scores. These results suggest that a reduction in lower limb perfusion, among other factors, plays a significant role in the pathogenesis leading to muscle spasticity after SCI. / text

published_or_final_version / Nursing Studies / Master / Master of Nursing in Advanced Practice

published_or_final_version / Paediatrics / Master / Master of Philosophy

Bipeds and quadrupeds are inherently unstable and their bodies sway during quiet stance and require complex patterns of muscle activation to produce direction-specific forces to control the body’s center of mass. The relative strength of length and force feedback within and across muscles collectively regulates the mechanical properties of the limb as a whole during standing and locomotion (Bonasera and Nichols 1994; Ross and Nichols 2009). Loss of posture control following spinal cord injury (SCI) is a major clinical challenge. While much is known about intermuscular force feedback during crossed extension reflex (XER) and locomotion in decerebrate cats, these have not been well characterized in animals with spinal cord injury. In this study, we mapped the distribution of heterogenic force feedback in hindlimb ankle extensor muscles using muscle stretch (natural stimulation) in intercollicular, non-locomoting, decerebrate cats with chronic lateral spinal hemisection (LSH). We also, determined the time of onset of redistribution of heterogenic force feedback following LSH by collecting force feedback data from cats with acute sci. In addition we revisited heterogenic force feedback between ankle extensors in decerebrate non-locomoting cats during mid-stance to ascertain whether these cats with intact spinal cord depict a certain pattern of force feedback. The goal was to ascertain whether the patterns and strength of feedback was different between the two states (cats with intact spinal cord and cats with SCI). We found that heterogenic feedback pathways remained inhibitory in non-locomoting decerebrate cats in two states. The latencies of inhibition also corresponded to those observed for force feedback from Golgi tendon organs. We observed variable patterns of force feedback between ankle extensors in decerebrate/control cats. On the other hand we observed consistent results in cats with chronic LSH exhibiting very strong distal to proximal pattern of inhibition from 2 weeks to 20 weeks following chronic LSH. The same results were obtained in acute LSH cats suggest that the change in neuromuscular system appears immediately after SCI and persists even after the animal start walking following SCI. The observed altered pattern of force feedback after spinal cord injury suggests either presence of a pattern intrinsic to the spinal cord or a unique pattern exhibited by the damaged spinal cord. The results are important clinically because even with vigorous rehabilitation attempts patients do not regain posture control after SCI even though they regain ability to walk. Therefore, to effectively administer treatment and therapy for patients with compromised posture control, a complete understanding of the circuitry is required.

No description available.

No description available.