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The purpose of this study, therefore, was threefold in nature: (1) to determine the effects of x-irradiation on the influx and efflux of potassium in compound nerve fibers (2) to attempt to relate the radiation-induced changes in electrical activity with potassium flux and (3) to use the information obtained to gain insight into the possible cellular site (s) of radiation insult to compound nerves.

by Leung Shiu Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 137-146. / Chapter CHAPTER ONE --- Introduction --- p.1 / Chapter 1.1 --- Surgical intervention done for nerve injury --- p.1 / Chapter 1.2 --- Rehabilitation procedures after nerve injuries --- p.2 / Chapter 1.3 --- Frustrating result of recovery after nerve injuries --- p.3 / Chapter 1.4 --- Reasons for the poor results --- p.3 / Chapter 1.5 --- Objective of the study --- p.5 / Chapter 1.6 --- Hypothesis and organization of the study --- p.6 / Chapter CHAPTER TWO --- The effects of pulsed electromagnetic field on peripheral nerve regeneration --- p.8 / Chapter 2.1 --- Electrical field and nerve growth --- p.8 / Chapter 2.2 --- Experimental findings of effect of the electromagnetic field on peripheral nerve regeneration --- p.9 / Chapter 2.3 --- The diversity of interest --- p.17 / Chapter CHAPTER THREE --- Physiological effects of the pulsed electromagnetic field --- p.18 / Chapter 3.1 --- The conventional use of electromagnetic field in musculoskeletal rehabilitation --- p.18 / Chapter 3.2 --- The pulsed electromagnetic field --- p.18 / Chapter 3.3 --- Nature of the pulsed electromagnetic field with a carrier frequency of 27.12 MHz --- p.19 / Chapter 3.4 --- Therapeutic effects of the pulsed electromagnetic field --- p.20 / Chapter 3.5 --- Some experimental results of the pulsed electromagnetic field --- p.20 / Chapter 3.6 --- Discussion --- p.25 / Chapter CHAPTER FOUR --- Methology --- p.27 / Chapter 4.1 --- Experimental animals and aneasthesia --- p.27 / Chapter 4.2 --- Models of lesions --- p.28 / Chapter 4.3 --- Sample size and grouping of the experimental rats --- p.35 / Chapter 4.4 --- Pulsed electromagnetic field stimulation --- p.37 / Chapter 4.5 --- Methods of evaluating the nerve regeneration --- p.38 / Chapter 4.6 --- Statistical analysis --- p.53 / Chapter CHAPTER FIVE --- Results --- p.54 / Chapter 5.1 --- Directly repaired groups --- p.54 / Chapter 5.2 --- Crushed groups --- p.62 / Chapter 5.3 --- Artery bridge groups --- p.73 / Chapter 5.4 --- Sham operated groups --- p.84 / Chapter 5.5 --- Electron microscopic examination --- p.90 / Chapter 5.6 --- Summary of all the data --- p.94 / Chapter CHAPTER SIX --- Discuss ion --- p.96 / Chapter CHAPTER SEVEN --- Conclusion --- p.103 / Chapter 7.1 --- Restatement of the experimental objective and hypothesis --- p.103 / Chapter 7.2 --- Conclusion --- p.103 / Chapter 7.3 --- Suggestions for furthur research --- p.104 / Chapter 7.4 --- Clinical Implication --- p.105 / Chapter APPENDIX I --- Determination of the duration of survival of the experimental animal --- p.106 / Chapter APPENDIX II --- Perfusion of rats --- p.115 / Chapter APPENDIX III --- Horseradish peroxidase and tetramethvlbezindine reaction --- p.118 / Chapter APPENDIX IV --- Histology fixation --- p.120 / Chapter APPENDIX V --- Determination of the Position of the Histology Specimens --- p.121 / Chapter APPENDIX VI --- Raw Data Collected in the Experiment --- p.132 / REFERENCE --- p.137

The peripheral nervous system (PNS) is composed of a diverse array of neurons that mediate sensation. This includes sensory circuits that encode external stimuli, as well as circuits that provide information flow from our internal organs. My PhD training has focused on addressing two questions: 1) what molecular mechanisms underlie this functional diversity, and 2) can we engineer non-invasive therapeutics to modulate PNS activity? To study the molecular mechanisms of sensory function, I employed the Merkel-cell neurite complex as a model system. Merkel cells are mechanosensory epidermal cells that have long been proposed to activate neuronal afferents through chemical synaptic transmission. RNA sequencing of adult mouse Merkel cells demonstrated that they express presynaptic molecules and biosynthetic machinery for adrenergic transmission. Moreover, live-cell imaging showed that Merkel cells mediate activity- and VMAT- dependent release of fluorescent catecholamine neurotransmitter analogues. Touch-evoked firing in Merkel-cell afferents was inhibited either by silencing of SNARE-mediated vesicle fusion from Merkel cells or by neuronal deletion of b2-adrenergic receptors. Next, to develop non-invasive technologies for peripheral nerve modulation, I employed targeted focused ultrasound (FUS) stimulation and electrophysiology to record activity of individual mechanosensory neurons. Parameter space exploration showed that stimulating neuronal receptive fields with high-intensity, millisecond FUS sonication reliably and repeatedly evoked action potentials in peripheral neurons. FUS elicited action potentials with latencies comparable to electrical stimulation, demonstrating both speed and reliability of the technique. Lastly, I show that peripheral neurons can be both excited by FUS stimulation targeted to either skin receptive fields or peripheral nerve trunks, a key finding that increases the therapeutic range of FUS-based peripheral neuromodulation.

With the increase of hand pathologies in the last decade, the need to better understand the anatomy of the hand is becoming more vital. The cutaneous innervation of the hand is classically described to be supplied by palmar cutaneous branch of the median nerve (PCBMN), common digital nerves (CDNs), ulnar nerve (UN), palmar cutaneous branch of the ulnar nerve, dorsal branch of the ulnar nerve (DBUN), superficial branch of the radial nerve (SBRN) and occasionally the lateral antebrachial cutaneous nerve (LABCN). Although the sensory distribution of the hand has been described in the literature, reports have often shown contradicting views and occasionally different or incomplete descriptions. Furthermore, clinical procedures in the hand and wrist can result in painful and/or disabling postoperative complications. This thesis outlines, categorizes and describes the distribution and branching patterns of cutaneous branches supplying the palmar and dorsal surface of the hand and their relationship to the distal area of the forearm and wrist. It also investigates the palmar and dorsal communicating branches, their patterns and common locations. Moreover, the project discusses the impact of the distribution and branching patterns of the cutaneous nerves on surgical and diagnostic procedures performed in the hand, wrist and distal forearm. 160 cadaveric hands were dissected in the Centre for Anatomy and Human Identification (CAHID), University of Dundee. All cadavers were musculoskeletally mature adults with mean age of 82.5±9.4 (range: 53-101) years. Skin was removed from the distal half of the forearm to the metacarpophalangeal joints. Nerves under investigation were identified, dissected, and traced. Sketches, photographs, and measurements to predefined landmarks including the wrist crease (WC), bistyloid line (BSL) and the third metacarpophalangeal (MCP) joint were taken and results expressed as means, standard deviations and ranges. Patterns are classified and expressed with frequencies. The PCBMN was found to originate from the main trunk of the median nerve (MN) 54.1±15.7 mm proximal to the WC and course distally between flexor carpi radialis and palmaris longus (if present) to innervate the proximal palmar surface of the hand by branching into one of three types identified. Furthermore, two PCBMN were found in 8.9% of cases. The second, third, fourth CDNs were found to divide into proper digital nerves at a point located distal to the 70% of the distance between the third MCP joint and the BSL in 88% of cases. The cutaneous innervation of the palm was found to be relatively constant with the lateral 3½ digits being supplied by the MN and the medial 1½ being supplied by the UN. A palmar CB was found between the third CDN-MN and fourth CDN-UN in 86.9% of the cases coursing in different patterns and changing the palmar sensory innervation of that previously described. The sensory innervation of the dorsum of the hand was variable. The most common pattern was being supplied by the SBRN innervating the lateral dorsal skin and the skin covering the lateral 2½ digits and the DBUN innervating the medial dorsal skin and the skin covering the medial 1½ digits found in 37.3%. All radial supply to the dorsum of the hand with the absence of the DBUN was found in 6.7%. The SBRN connected with the LABCN in 30.7% and with the DBUN in 26.4% complicating the sensory innervation in the dorsum of the hand. Understanding the cutaneous innervation of the hand, appreciation of the possible variations and presence of communicating branches will result in a better evaluation of signs and symptoms, establishing a proper therapeutic plan, avoiding iatrogenic injuries during surgical interventions, and properly diagnose postoperative complications leading to an increased quality of medical service and patient satisfaction.

Thesis (M. Med (Rad. Diagn.)) --University of Limpopo, Medunsa Campus, 2011 / Objective: The objective was to determine the incidence of missed pathology on normal non contrast enhanced cranial computed tomography (NECT).Method: Records of cranial computed tomography scans done over a 12 month period at the Dr George Mukhari Hospital were evaluated by three readers. The NECT and contrast enhanced cranial computed tomography (CECT) were read at separate occasions and readers did not have access to a history, each other’s interpretation or to their own interpretation of the NECT when the CECT was evaluated. The data was evaluated and analysed after the 3 readers had seen the cases individually. Interpretation discrepancies were resolved during a meeting between all 3 readers and consensus was reached. Cases with missed pathology on the NECT were evaluated retrospectively at a joint meeting between the 3 readers to determine whether the pathology was visible on the NECT and thus to determine the combined reader error rate. Results: In this study 3.28 % of cases had pathology missed by 3 readers on the NECT. Retrospective viewing reduced this to 1.42% indicating a reader error of 1.85%. This incidence of missed pathology correlates with the most recent studies done. Having a thorough medical history of the patient and selecting those with clinical findings indicating the need for a CECT will reduce the incidence of missed pathology.Conclusion: Patients with a normal NECT and no fever, meningism, confusion, focal/lateralizing signs, a history of tuberculosis or tumours, or risk factors for dural venous sinus thrombosis have a very small chance of missed pathology on NECT. The risk of contrast induced adverse events outweighs the risk of missing pathology on a normal NECT provided there is no clinical indication necessitating a CECT. Omitting unnecessary CECT will in turn reduce the risk of intravenous iodinated contrast and the radiation exposure to the patient. These two factors will ultimately reduce the running cost of the CT department and increase the throughput of patients. Alternatively omitting the NECT will reduce the radiation exposure to the patient.Reporting errors can be reduced by assessing and managing risk factors in each department i.e. viewing conditions and workload.

Vagal and spinal sensory afferent innervation are responsible for to regulation of neurogenic inflammation in the airways. Neurogenic inflammation is a complex process involving vasodilatation,plasma protein extravasation and edema,glandular secretion and immunoinflammatory cell chemotaxis and activation. Plasma extravasation is the result of the activation of sensory nerve endings and the subsequent prodution of neuropeptides, namely, tachykinins such as substance P, neurokinin A and neurokinin B. SP was more potent than NKA or NKB in increasing microvascular permeability, which indicate that tachykinin NK-1 receptors are mainly involved in neurogenic inflammation in the airways of rat. When 6-hydroxydopamine¡]6-OHDA¡^was infused into the tracheal lumen,it causes plasma extravasation in the tracheal mucosa mediated by sensory nerve axons. Local application of 6-OHDA to stellate ganglion, had no effect on neurogenic inflammation and SP-IR innervation in the airways.The present study was to investigate the effect of intravenous injection of 6-OHDA on plasma leakage in the airways.This study also used the NK-1 receptor antagonist L-732,138 to investigate if 6-OHDA-induced plasma leakage in the airways was related to NK-1 receptors. India ink was used as tracer dye to label the leaky microvessels to evaluate the magnitude of inflammation . We found that 6-OHDA in the doses of 25 mg/kg and 50 mg/kg caused an extensive increase in plasma extravasation in the trachea and bronchi. But the vehicle¡]1 ¢ML-ascorbic acid and 0.4 ¢MNaCl, pH 3.4¡^caused a slight plasma leakage. Intravenous administration of L-732,138 decrease 6-OHDA induced plasma leakage. But one week after vagal transection, 6-OHDA-induced plasma extravasation in the ipsilateral airways was not significatly reduced. It is suggested that intravenous 6-OHDA stimulated bronchopulmonary C-fibers and resulted in vagal C-fiber release of tachykinins that produced acute inflammation in the lower airways. Intravenous application of L-732,138 significantly reduced the 6-OHDA-induced plasma leakage, suggesting that NK-1 receptors in the venular endothelial cells mediate the inflammatory response in the layynx,trachea,bronchi.and esophagus of the rat .

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 123-155).

Ph.D.

The golden method of peripheral nerve system injury is the nerve autograft, but it is associated with drawbacks such as donor site morbidity, needs of second incisions and the shortage of nerve grafts. Comparatively, connecting the nerve defect directly is an alternative. Unfortunately, if the defects are long, the induced tension will deteriorate the nerve regeneration. These limitations led to the development of artificial nerve guidance conduit (NGC). The market available NGC have problems of unsatisfactory functional recovery and may collapse after the implantation. These are attributed to material and structural deficiencies. Therefore, there is essential to study a biomaterial, which has excellent biological and physical properties to fit the NGC application. In addition, some studies suggested that the poor functional recovery resulted from the NGC implantation were due to the lack of micro-guidance inside the conduit. Thus, it is necessary to investigate the structural influence on the functional recovery of peripheral nerve injury. Crosslinked urethane-doped polyester elastomer (CUPE) is newly invented for a blood vessel graft because it possesses similar mechanical properties of blood vessel which is similar to nerve as well. Therefore, CUPE was also considered to be the NGC. Its biocompatibility has been proved to be excellent in the previous study done by Dr. Andrew SL, Ip. Targeting on the long peripheral nerve regeneration, the aims of this study are (1) to investigate the biocompatibility of CUPE in in-vitro condition and (2) to study the influence of nerve-like structure on the peripheral nerve system injury in an animal model. The ultimate goal is to enhance the functional recovery of peripheral nerve system injury by implanting a flexible biomaterial, CUPE, which has a nerve-like microarchitecture. It is hypothesized that the nerve-like structure can promote the axonal regeneration. The surface energy and roughness of CUPE were investigated. It showed a relatively low surface energy compared to other conventional biopolymers such that the cell adhesion and also the proliferation were inhibited. Therefore, the CUPE was modified by the immersion into a high glucose DMEM. The change in the hydrophilicity, roughness and cell viability of medium treated CUPE were studied. The hydrophilicity of treated CUPE was increased but the roughness was remaining unchanged whereas the pH of the immersion solution did not cause any effect on the cell activity on the CUPE. In the pilot animal study, five channels along the CUPE-NGC had a similar myelinated fiber density and population compared to the nerve autograft. Also, the channels in the CUPE-NGC were fragmented. In summary, the medium treatment could enhance the hydrophilicity of CUPE and the cell activity on CUPE. Such modifications did not governed by the pH of the medium. The NGC-CUPE with five channels, which imitated a basic nerve structure was shown to have a similar tissue regeneration and the functional recovery as the nerve autograft did. The results proved the hypothesis that the nerve-like structure can promote the functional recovery of peripheral nerve system injury with the use of a new biomaterial, CUPE as the NGC substrate. / published_or_final_version / Orthopaedics and Traumatology / Master / Master of Philosophy