Thesis (M. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

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Thesis (Ph. D.)Open University. BLDSC no. DXN036583.

Thesis (Ph. D.)--Open University. BLDSC no. DXN043607.

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 106-128).

This thesis aimed to investigate the feasibility of two diffusion imaging techniques, Diffusion Tensor Imaging (DTI) and Diffusion Kurtosis Imaging (DKI), on detecting subtle physiological or pathological microstructural changes in normal-appearing neural tissues of human central nervous system. 　　　At first, ten patients with neuromyelitis optica (NMO) and twelve age- and gender-matched healthy subjects were recruited. DTI-derived indices including fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivities were quantified in the lateral and dorsal columns of cervical spinal cord. Based on the regions of interest (ROIs) measurement, NMO patients showed reduced FA, increased MD and radial diffusivity compared to control subjects, while axial diffusivity did not show any significant difference. The three former DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO. Our results show that DTI-derived indices can quantitatively assess the white matter (WM) abnormalities with seemingly normal appearance in conventional MRI, and are associated with the level of clinical disability, suggesting that DTI may have great potential as a useful diagnostic tool in the clinical setting. 　　　DKI is an extension of conventional DTI to probe the non-Gaussian diffusion property in biological tissues. Besides the four conventional DTI-derived metrics, DKI also provide three additional kurtosis metrics (mean kurtosis (MK), axial and radial kurtosis). In the second study, ROI-based analysis was used to characterize age-related microstructural changes in WM, cortical and subcortical gray matter (GM) of 27 healthy adults (21~59 yrs). Though the volumes of GM and WM were still preserved, DTI-derived metrics can detect the subtle changes in WM and GM. Meanwhile, MK and radial kurtosis significantly increased in both caudate nucleus and putamen while Thalamus showed little aging effect in the diffusivity and kurtosis metrics but significantly decreased only in FA. Our results demonstrated that DKI is sensitive to detect the age-related alterations in neural microstructures at the stage of early aging. 　　　In addition, DKI has been applied to detect the pathological changes in the normal-appearing neural tissues of 18 patients with multiple sclerosis (MS), compared to 22 healthy controls. Diffuse WM abnormalities have been observed extensively in the brain, revealed by DKI-derived metrics. Though the volumetric and voxel-wise analysis revealed no significant changes in the volume of cortical GM, decreased FA and kurtoses with increased diffusivities in MS group were sensitive to disclose the subtle alterations in global and regional cortical GM tissues. Significant correlations have been found between FA in the global, frontal and temporal cortical GM in relapsing-remitting MS patients and their disability scores, suggesting FA as an important biomarker to monitor the disease progress in cortical GM. Moreover, elevated kurtosis indices in MS patients did not correlate with diffusivities in caudate nucleus, putamen and thalamus, suggesting these metrics may be vulnerable to different pathologic aspects of the disease. 　　　In conclusion, DKI is sensitive to neural alterations during normal aging and in MS pathologies, and can provide complementary information to conventional MRI and DTI. / published_or_final_version / Diagnostic Radiology / Doctoral / Doctor of Philosophy

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The purpose of the study was to investigate a possible connection between alpha-l-antitrypsin (A1AT) deficiency and familial epilepsy and mental retardation of possible congenital or genetic origin.The individuals were genotyped by using a two dimensional cross-electrophoretic procedure. The electrophoretic procedure involved isoelectric focusing on an acid-starch gel followed by immunoelectrophoresis. The control and experimental groups were then statistically compared to population norms by using the chi-square test. The 0.05 level of significance was established as the critical probability level for the nonacceptance of a connection.ResultsOf the 49 individuals in the control group, 46 had, a protease inhibitor (Pi) genotype of PiMM 1 , and there was 1 each of the Pi MF, Pi MS, and Pi Mz genotypes. Of the 50individuals in the familial epilepsy experimental group, 43 were genotyped as PiMM, 2 as PiMS, and 5 as PIMF. Of the 16 individuals in the mental retardation experimental group, 14 were genotyped as PiMM, 1 as PiMS, and 1 as PiMF.The probability of reoccurrence for the various groups were: control - 0.3 to 0.5; familial epilepsy - 0.3 to 0.5; and mental retardation - 0.7 to 0.8.Conclusions1. The applicability of starch gel electrophoresis in a clinical setting is questionable because of cost, length of time required, and difficulty in handling.2. The control group demonstrated no statistical variation in the 1AT frequency from general population norms.3. The familial epilepsy experimental group showed no statistical evidence linking it to abnormal A1AT genotypes.4. The mental retardation experimental group demonstrated no statistical evidence linking it to abnormal A.1 AT genotypes.

Dystonia is a little known neurological disease of the central nervous system and consists of a group of related movement disorders, characterised by involuntary and prolonged spasms of muscle contraction. Although it is nearly 90 years since this neurological disorder was first named, relatively little research had been undertaken into dystonia, for the first 65 years and it was not until the mid 1970's that researchers started to look at the disorder. This particular programme of research has taken place exactly over a six year period, starting in May 1993, and relates to a large number of different areas of study. This research has proven that dystonia is far more prevalent than previously thought, it is next to Parkinson's Disease in degree of prevalence and is far more common than other better known neurological conditions, such as Motor Neurone Disease, and yet it remains largely unknown to most members of the medical profession and the general public at large. Dystonia has been historically extremely difficult to diagnosis and this meant it has been previously very difficult to obtain sufficient numbers for study, which in turn has created a number of significant social and economic consequencesw, hich has mainly meant that most cases of people with dystonia have remained undiagnosed or misdiagnosed for many years. This research was designed to measure the severity and prevalence of dystonia in the northern part of the UK, the implication the disease has had on the working life and environment of each patient and how that person is coping with the various personal, social and family relationships caused by the onset and potential gradual deterioration of the disorder, as well as measuring the quality of life of each patient during a number of different therapies. Although there has been research into other neurological disabilities, very little is known about the implications that dystonia can have on the affected person and their families. This is the first time that all types of dystonia have been studied and that certain related subjects have been specifically included. This research has been enormously helped by the tremendous expansion in the use of Botulinurn Toxin therapy and although an enormous amount of work has been completed and accomplished during this research programme, it should never be forgotten that the subjects of this thesis are real people and that the implications and results of this research have had, and will have, a tremendous impact on their lives and that of their families.