Author
Myrlene Gee
Bio: Myrlene Gee is an academic researcher from University of Alberta. The author has contributed to research in topics: Medicine & Parkinson's disease. The author has an hindex of 12, co-authored 17 publications receiving 867 citations.
Topics: Medicine, Parkinson's disease, Dementia, White matter, Hyperintensity
Papers
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TL;DR: High field strength MRI demonstrates lateral substantia nigra pars compacta abnormalities in early Parkinson disease (PD) consistent with increased iron content and corresponding to the known distribution of neuronal loss occurring in this disorder.
Abstract: Background: Parkinson disease (PD) is a progressive neurodegenerative disorder in which the major pathologic substrate is a loss of dopaminergic neurons from the lateral substantia nigra pars compacta (SNc). Our objective was to determine whether, in patients with early PD, SNc changes evident on MRI sequences sensitive to iron content corresponded anatomically to the pathologic changes reported previously, and to correlate these changes to the duration and severity of clinical manifestations of PD. Methods: Twenty-six untreated patients with early PD and 13 age- and gender-matched control subjects had MRI with a 3 tesla magnet using a multiple gradient echo sequence designed for rapid single-scan mapping of the proton transverse relaxation rate ( R 2 * ). R 2 * was calculated for midbrain and forebrain basal ganglia regions. Clinical features were rated with the Unified Parkinson9s Disease Rating Scale. Results: A difference in measured R 2 * values between patients and controls was observed in the lateral SNc ( p ≤ 0.005). Linear regression indicated a correlation between the lateralized motor score from the clinically most affected side and R 2 * values from the opposite lateral SNc ( p = 0.01). Conclusions: High field strength MRI demonstrates lateral substantia nigra pars compacta abnormalities in early Parkinson disease (PD) consistent with increased iron content and corresponding to the known distribution of neuronal loss occurring in this disorder. This may ultimately provide an imaging marker for disease progression in PD, although longitudinal studies are required. GLOSSARY: AC = anterior commissure; CN = caudate nucleus; GP = globus pallidus; LantGP = left anterior GP; LantPu = left anterior Pu; LlatSNc = left lateral SNc; LlatSNr = left lateral SNr; LmedSNc = left medial SNc; LmedSNr = left medial SNr; LpostGP = left posterior GP; LpostPu = left posterior Pu; PC = posterior commissure; PD = Parkinson disease; Pu = putamen; RantGP = right anterior GP; RantPu = right anterior Pu; RlatSNc = right lateral SNc; RlatSNr = right lateral SNr; RmedSNc = right medial SNc; RmedSNr = right medial SNr; RN = red nucleus; ROI = region of interest; RpostGP = right posterior GP; RpostPu = right posterior Pu; SNc = substantia nigra compacta; SNr = substantia nigra reticulata; TE = echo times; UPDRS = Unified Parkinson9s Disease Rating Scale.
340 citations
TL;DR: Cortical and striatal atrophy were associated with dopamine non-responsive motor signs and cognitive impairment and provide a morphologic correlate for progression of PD.
91 citations
TL;DR: A series of organic hydrochloride salts have been investigated using solid-state 35Cl and 37Cl NMR spectroscopy at applied magnetic field strengths of 9.4 and 18.8 T.
Abstract: A series of organic hydrochloride salts has been investigated using solid-state 35Cl and 37Cl NMR spectroscopy at applied magnetic field strengths of 9.4 and 18.8 T. Magic-angle spinning, static Hahn-echo, and quadrupolar Carr−Purcell Meiboom−Gill (QCPMG) echo experiments have been applied to investigate the chlorine electric field gradient (EFG) and chemical shift (CS) tensors for l-tyrosine hydrochloride, l-cysteine methyl ester hydrochloride, l-cysteine ethyl ester hydrochloride, quinuclidine hydrochloride, and tris sarcosine calcium chloride. Chlorine-35 nuclear quadrupolar coupling constants for these compounds range from 2.23 to 5.25 MHz, and isotropic chemical shifts range from approximately 9 to 53 ppm relative to the chloride ion in aqueous solution. The results demonstrate the feasibility and benefits of high-field 35/37Cl NMR studies of organic chloride salts. A discussion of the data in the context of the known X-ray or neutron diffraction structures for these compounds suggests that the chlor...
82 citations
TL;DR: It is suggested that right anterior temporal lobe changes occur in untreated patients with PD, and the earliest changes may occur in subcortical white matter rather than temporal cortex.
Abstract: The purpose of this study was to determine if focal cortical abnormalities may occur in early Parkinson's disease (PD). We studied 26 untreated patients with early PD and 14 healthy control subjects, with cognitive screening and magnetic resonance imaging (MRI). Voxel-based morphometry was used to assess for the presence of localized cortical grey matter (GM) and/or subcortical white matter (WM) changes. Patient and control groups showed no differences in age or gender distribution. Females had a greater GM% than males (P = 0.001). Comparison of patients and controls revealed no difference in local GM volumes. In PD, however, there was decreased WM volume in the anterior right fusiform gyrus and superior temporal gyrus. There were no correlations between the California Verbal Learning Test long delay free recall, Judgment of Line Orientation, Trail Making A or B and either the GM or WM localized volumes. These results suggest that right anterior temporal lobe changes occur in untreated patients with PD. The earliest changes may occur in subcortical white matter rather than temporal cortex.
73 citations
TL;DR: The present study found intact limbic connectivity but suggests that amygdala atrophy may be present in Parkinson's disease with depression, and further work is needed to replicate these findings.
72 citations
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9,362 citations
TL;DR: This cornucopia will be coveted and dipped into by those neurologists with a special interest in abnormal movement disorders, but who would not consider themselves to have a research interest in tremor.
Abstract: on to develop full blown Parkinson's disease with rigidity and bradykinesia in the next few years. For those interested in the mechanisms of tremor, there are the customary authoritative reviews by Llinas, De Long, Lamarre, Rothwell and Deuschl, but uncertainty remains with respect to the relative importance of central autonomous generators and instability of peripheral reflex loops. Well written chapters are also included on primary orthostatic tremor and its relationship to essential tremor, writing tremor, neuropathic tremor, midbrain tremor and the increasingly acknowledged psychogenic tremors. Complex interrelationship between dystonia and postural tremor is also covered in depth. This cornucopia will be coveted and dipped into by those neurologists with a special interest in abnormal movement disorders, but who would not consider themselves to have a research interest in tremor. However, for the majority of clinicians involved in the hurly burly of clinical practice, I suspect that regrettably time and cost factors will conspire together to keep this excellent book out of reach. ANDREW LEES
1,150 citations
TL;DR: MRI can often identify changes in iron homoeostasis, thus providing a potential diagnostic biomarker of neurodegenerative diseases and an important avenue to reduce iron accumulation is the use of iron chelators that are able to cross the blood-brain barrier, penetrate cells, and reduce excessive iron accumulation, thereby affording neuroprotection.
Abstract: Summary In the CNS, iron in several proteins is involved in many important processes such as oxygen transportation, oxidative phosphorylation, myelin production, and the synthesis and metabolism of neurotransmitters. Abnormal iron homoeostasis can induce cellular damage through hydroxyl radical production, which can cause the oxidation and modification of lipids, proteins, carbohydrates, and DNA. During ageing, different iron complexes accumulate in brain regions associated with motor and cognitive impairment. In various neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease, changes in iron homoeostasis result in altered cellular iron distribution and accumulation. MRI can often identify these changes, thus providing a potential diagnostic biomarker of neurodegenerative diseases. An important avenue to reduce iron accumulation is the use of iron chelators that are able to cross the blood–brain barrier, penetrate cells, and reduce excessive iron accumulation, thereby affording neuroprotection.
1,089 citations
TL;DR: It is concluded that SWI often offers complementary information valuable in the diagnosis and potential treatment of patients with neurologic disorders, as well as a variety of neurovascular and neurodegenerative disease applications for SWI.
Abstract: SUMMARY: Susceptibility-weighted imaging (SWI) has continued to develop into a powerful clinical tool to visualize venous structures and iron in the brain and to study diverse pathologic conditions. SWI offers a unique contrast, different from spin attenuation, T1, T2, and T2* (see Susceptibility-Weighted Imaging: Technical Aspects and Clinical Applications, Part 1). In this clinical review (Part 2), we present a variety of neurovascular and neurodegenerative disease applications for SWI, covering trauma, stroke, cerebral amyloid angiopathy, venous anomalies, multiple sclerosis, and tumors. We conclude that SWI often offers complementary information valuable in the diagnosis and potential treatment of patients with neurologic disorders.
701 citations
TL;DR: C and 35/37Cl NMR relaxation measurements on several model systems demonstrate that the solvation of cellulose by the ionic liquid 1-n-butyl-3-methylimidazolium chloride involves hydrogen-bonding between the carbohydrate hydroxyl protons and the IL chloride ions in a 1 ratio 1 stoichiometry.
696 citations