Previous work has demonstrated that rhythmic motor outputs, such as locomotion and scratch induce a hyperpolarization of the voltage threshold (Vth) for action potential initiation in spinal motoneurons, enhancing their excitability. Descending monoamines were implicated in mediating this effect; however, the recent observation that changes in Vth persist during fictive scratch in cats following acute cervical transection revealed that intraspinal systems, of unknown neuromodulatory identity, also have the ability to regulate motoneuron excitability during motor behaviour. This thesis addresses: 1) whether acetylcholine (ACh) is able to modulate spinal motoneuron Vth, and 2) whether endogenous ACh modulates motoneuron excitability during motor activity without intact descending modulation. Our first study investigates whether ACh from exogenous and/or endogenous sources alters motoneuron Vth. We made intracellular recordings of lumbar motoneurons from neonatal rats to pharmacologically manipulate muscarinic and nicotinic receptor activity. Results show that ACh induces either Vth hyperpolarization, Vth depolarization or no change in Vth depending on the activity state of the network, the ACh concentration, and influences from other systems. Our second study investigates whether intraspinal cholinergic inputs induce Vth hyperpolarization during rhythmic motor output when descending projections are disrupted. For this we developed an in vitro neonatal rat spinal cord preparation to elicit rhythmic activity independently of brainstem or lumbar cord stimulation. Intracellular recordings from motoneurons allowed comparison of the Vth prior to and during rhythmic output, both in the absence and presence of cholinergic antagonists in the lumbar cord. Results show that intraspinal cholinergic mechanisms are active and importantly contribute to modulation of motoneuron Vth during motor output. We suggest that in addition to descending modulation, the spinal cholinergic system regulates motoneuron Vth to either facilitate or inhibit recruitment according to the motor network state. Motoneuron excitability regulation by modification of distinct membrane properties resulting from separate modulatory systems activation during diverse motor behaviours is discussed. This work is the first to demonstrate the role of cholinergic mechanisms in regulating motoneuron excitability through modulation of Vth in an activity based context, and therefore outlines a spinal modulatory system that would contribute to motor control in both normal and pathological states. / May 2016

M.Tech. / OBJECTIVE: The aim of this study was to determine whether adjustment of the cervico-thoracic motion segment in individuals with altered or decreased motion at that segment, in conjunction with a strengthening protocol, had a greater increase in triceps brachii muscle strength compared to a strengthening protocol or chiropractic adjustment alone. By reducing the negative neural and other effects caused by aberrant movement between vertebra, chiropractic adjustment could allow the body’s muscle physiology to function at its best, thereby allowing it to adapt to changes more readily. DESIGN: Thirty subjects participated in this study. The subjects were randomly and without being aware of it, assigned to one of three groups. The only requirement for inclusion in the research was a restriction of the seventh cervical vertebra based on motion and static palpation. Patients in two of the groups were asked to perform tricep brachii muscle strengthening exercises and patients from two of the groups received chiropractic adjustment to the cervico-thoracic motion segment. Patients were seen a total of three times over a period of two weeks. MEASUREMENTS: Triceps brachii muscle strength testing was performed using an isometric dynamometer. Three pre-treatment readings and three post-treatment readings were performed, with one-minute intervals, on all the subjects. This was done to determine if there was a change before or after treatment and if there was a long-term effect. CONCLUSION: Although measurements were taken on each visit before and after each treatment, there was only a statistically significant difference in triceps brachii muscle strength between the experimental and the other two groups before treatment on the third visit. This does however; suggest that there was a favourable result and that a combination of treatments does indeed produce better results than one of the other treatments alone.

A research report submitted to the Faculty of Medicine, University of Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Medicine in the branch of Anaesthesia. / Spinal anaesthesia for Caesarean section is associated with an unacceptably high incidence of hypotension despite the administration of an intravenous fluid preload and the use of uterine displacement. The theoretical benefits of preventing hypotension as opposed to treating it as it occurs are the avoidance of considerable maternal discomfort, a reduced risk of serious cardiovascular or respiratory depression and the avoidance of transient foetal asphyxia. The use of prophylactic intramuscular ephedrine prior to spinal anaesthesia has been recommended but not well studied. The advantages of the intramuscular route for ephedrine administration are its simplicity and its favourable pharmacokinetic profile. Cardiovascular support is sustained throughout the surgery and into the post operative period. Opposition to the use of intramuscular ephedrine in the prevention of hypotension is based on two studies in which spinal anaesthesia was not used [1,2]. These studies showed an unacceptably high incidence of hypertension, a deleterious effect on foetal gas exchange and a lack of efficacy when intramuscular ephedrine was used in epidural and general anaesthesia respectively. This research report describes a randomised, double blind, interventional study designed to assess the safety (prevalence of hypertension, tachycardia or foetal compromise) and efficacy (prevalence of hypotension) of 37,5mg of ephedrine given prior to spinal anaesthesia for Caesarean section. Forty patients who had given informed consent were entered into the study. Blood pressures and pulse rates were recorded for 90 minutes after ephedrine administration, samples of umbilical venous blood were collected and Apgar scores assessed. This study found that giving 37,5mg of intramuscular ephedrine prior to spinal anaesthesia was safe from a maternal point of view in that it was not associated with reactive hypertension or tachycardia. When the ephedrine was given 10 minutes prior to induction of the spinal the technique proved to be effective in reducing the incidence and severity of hypotension. When used in the above manner the technique was not associated with foetal depression or acidosis. / WHSLYP2016

Following cervical or upper thoracic level spinal cord injury (SCI), motor, sensory and autonomic systems are disrupted. One form of this autonomic dysfunction is the condition autonomic dysreflexia (AD), which is characterised by episodes of high blood pressure in response to afferent input from regions below the injury level. An animal model of autonomic dysreflexia, the T4 transected rat, was used in this thesis to gain insight into the cardiovascular and temperature components of the disorder, possible peripheral mechanisms and interventions to prevent its development. Chapter 2 of the thesis includes the charaterisation of a T4 transection rat model of spinal cord injury. This characterisation includes confirmation of decreased baseline mean arterial pressure (MAP, 71 down from 117 mmHg) and elevated heart rate (HR, 431 bpm from 366 bpm) for 6 weeks post injury (p.i.). Documentation of the development of AD found that hypertensive responses were fully developed (+20 mmHg) by 4 weeks p.i. Further, during episodes of AD at Weeks 4 and 5 p.i., tail surface temperatures decreased significantly (mid-tail, -1.7oC), indicative of extensive vasoconstriction. Comparison of vascular responses of intact and SCI animals to adrenergic agonists (phenylephrine, PHE and methoxamine, METH) following ganglionic blockade in vivo found that SCI animals experienced prolonged vasoconstriction in blood vessels above and below injury level in response to PHE but not METH. Possible mechanisms of this change included decreased neuronal reuptake of PHE (METH is not a substrate for neuronal reuptake). The presence of prolonged vasoconstriction in blood vessels throughout the body, not just regions below injury level, suggests a widespread mechanism for the change, such as the decreased basal MAP, norepinephrine levels or neural activity present following injury. Thus, it was hypothesised that increased activity from an early stage post injury may prevent the peripheral adaptation and perhaps hinder development of AD. For this, the common rehabilitation technique, treadmill training, was used. Surprisingly, rather than preventing AD, the training actually accelerated its development, producing exaggerated hypertensive responses to colorectal distension (CRD) at Weeks 3 and 4 post-injury (Week 4, Trained: +38.5 ?? 1.5 mmHg; Sedentary: 23.4 ?? 3.1mmHg). Comparison of vascular responses of both groups to PHE injection found no significant difference indicating that the enhanced responses were not a result of peripheral vascular changes. Investigation of the central morphology following SCI, made via immunohistochemical processing of the post-mortem spinal cords, found that Treadmill Trained SCI animals had elevated calcitonin gene related peptide (CGRP) immunoreactivity within lamina III/IV of lumbar segments, compared to intact cords. It is possible that this finding indicates afferent sprouting that may have accelerated the development of AD in Treadmill Trained animals. The results within this thesis highlight the importance of awareness and examination of autonomic function in SCI patients, especially those undergoing rehabilitative training.

Thesis (Ph. D.)--Drexel University, 2007. / Includes abstract and vita. Includes bibliographical references (leaves 111-123).

The vertebral column is the most common site of skeletal metastatic development secondary to breast cancer. Multiple clinical treatments are available for spinal metastasis, including systemic bisphosphonates and radiation therapy, however the success of current treatment approaches varies considerably. Alternative treatment strategies for spinal metastatic destruction must be aimed at both reducing tumor burden and restoring mechanical stability. Photodynamic therapy (PDT) has been shown to be successful at destroying osteolytic lesions in preclinical models of breast cancer spinal metastasis. However, the clinical feasibility of PDT for spinal metastasis is dependent on its potential effects on the structural integrity of vertebral bone. This thesis aims to determine the effects of PDT alone and in combination with bisphosphonate therapy on the structural architecture and mechanical properties of healthy and metastatically involved vertebrae. PDT was shown to have a positive effect on vertebral bone structure, alone and in combination with previous bisphosphonate therapy.

The vertebral column is the most common site of skeletal metastatic development secondary to breast cancer. Multiple clinical treatments are available for spinal metastasis, including systemic bisphosphonates and radiation therapy, however the success of current treatment approaches varies considerably. Alternative treatment strategies for spinal metastatic destruction must be aimed at both reducing tumor burden and restoring mechanical stability. Photodynamic therapy (PDT) has been shown to be successful at destroying osteolytic lesions in preclinical models of breast cancer spinal metastasis. However, the clinical feasibility of PDT for spinal metastasis is dependent on its potential effects on the structural integrity of vertebral bone. This thesis aims to determine the effects of PDT alone and in combination with bisphosphonate therapy on the structural architecture and mechanical properties of healthy and metastatically involved vertebrae. PDT was shown to have a positive effect on vertebral bone structure, alone and in combination with previous bisphosphonate therapy.

No description available.

Thesis (M.A.(Psychology))--University of Pretoria, 2001. / Includes bibliographical references (leave. 175-185).

Magnetic Resonance Imaging (MRI) has been applied in diagnosing Cervical Spondylosis Myelopathy (CSM) clinically. However, morphometric and signal change of MRI have not shown consistent relations with neurological function or outcome after surgical intervention. Diffusion Tensor Imaging (DTI) is an advanced MRI technology, which uses the principle of anisotropic water diffusion property. Recent studies indicated that DTI could be used as diagnostic tools for Cervical Spondylosis Myelopathy (CSM). The study aims to establish a Region of Interest (ROI)-based database. 65 healthy Chinese subjects were recruited for functional MR scanning. The effects on age and gender would also be investigated. Whole cord FA values decreased from upper cord level to lower cord level. White matter FA and AD values are significant higher than grey matter. White matter RD values are significant lower than grey matter. MD values of whole cord, white matter and grey matter are similar. There are no significant differences (P>0.05) of DTI metrics between males and females. There are significant differences (P<0.05) of DTI metrics in cervical spinal cord white matter in advancing age. / published_or_final_version / Orthopaedics and Traumatology / Master / Master of Medical Sciences