382 research outputs found
Fluoxetine as disease modifying treatment in multiple sclerosis : rationale, evaluation of the use of MRI to monitor treatment, and preliminary findings
No full textPatients with multiple sclerosis (MS) lack astrocytic β2-adrenergic receptors and this may contribute to the focal inflammatory demyelinating lesions and axonal degeneration that characterize this disease. We hypothesized that the antidepressant fluoxetine might be able to compensate for the loss of the β2-adrenergic receptors. In this thesis we evaluated the use of cerebral MRI scans to monitor disease activity and we performed several exploratory studies to evaluate effects of fluoxetine on patients with MS.
A convenient way to find out whether a drug is able to reduce disease activity in MS is by measuring the development of new focal lesions on serial MRI scans of the brain.
MS patients who received fluoxetine during 6 months had a trend towards the development of less new focal lesions compared to patients receiving placebo. To assess whether preventing new lesions formation reduces disability on the long term, we studied the relationship between the focal (T2) lesions and disease progression. The number of focal lesions predicted progression of disability and conversion to a progressive disease course in patients with relapsing remitting MS. However, once patients had entered the progressive phase, T2 lesions were no longer predictive for further progression of disability. In another study, we found that 2 weeks use of fluoxetine resulted in an increase in NAA/Cr (a marker of axonal function) in the white matter of MS patients.
These preliminary studies suggest that fluoxetine reduces new focal lesion formation and may improve axonal metabolism in MS patients.
Migraine as a Risk Factor for Subclinical Brain Lesions
No full textMark C. Kruit, Mark A. van Buchem, Paul A. M. Hofman, Jacobus T. N. Bakkers, Gisela M. Terwindt, Michel D. Ferrari, Lenore J. Launer (2004): Migraine as a Risk Factor for Subclinical Brain Lesions. JAMA 291 (4): 427-434, DOI: 10.5281/zenodo.103840
sj-pdf-2-wso-10.1177_17474930211057022 - Supplemental material for Spatial and temporal intracerebral hemorrhage patterns in Dutch-type hereditary cerebral amyloid angiopathy
No full textSupplemental material, sj-pdf-2-wso-10.1177_17474930211057022 for Spatial and temporal intracerebral hemorrhage patterns in Dutch-type hereditary cerebral amyloid angiopathy by Sabine Voigt, Siham Amlal, Emma A Koemans, Ingeborg Rasing, Ellis S van Etten, Erik W van Zwet, Mark A van Buchem, Gisela M Terwindt, Marianne AA van Walderveen and Marieke JH Wermer in International Journal of Stroke</p
sj-jpg-1-wso-10.1177_17474930211057022 - Supplemental material for Spatial and temporal intracerebral hemorrhage patterns in Dutch-type hereditary cerebral amyloid angiopathy
No full textSupplemental material, sj-jpg-1-wso-10.1177_17474930211057022 for Spatial and temporal intracerebral hemorrhage patterns in Dutch-type hereditary cerebral amyloid angiopathy by Sabine Voigt, Siham Amlal, Emma A Koemans, Ingeborg Rasing, Ellis S van Etten, Erik W van Zwet, Mark A van Buchem, Gisela M Terwindt, Marianne AA van Walderveen and Marieke JH Wermer in International Journal of Stroke</p
sj-jpg-3-wso-10.1177_17474930211057022 - Supplemental material for Spatial and temporal intracerebral hemorrhage patterns in Dutch-type hereditary cerebral amyloid angiopathy
No full textSupplemental material, sj-jpg-3-wso-10.1177_17474930211057022 for Spatial and temporal intracerebral hemorrhage patterns in Dutch-type hereditary cerebral amyloid angiopathy by Sabine Voigt, Siham Amlal, Emma A Koemans, Ingeborg Rasing, Ellis S van Etten, Erik W van Zwet, Mark A van Buchem, Gisela M Terwindt, Marianne AA van Walderveen and Marieke JH Wermer in International Journal of Stroke</p
Stability of a single top layer of cubes
No full textIn an attempt to reduce the cost of breakwaters, several elements have been developed. Examples are Accropodes, Tetrapods and concrete cubes. Previous tests were performed with armour layers consisting of a double layer of cubes. This study is based on a single layer of cubes. The great benefit of a single layer of cubes is that it reduces the total cost of concrete. Another benefit is that because of the shape, cubes are easy to prefabricate. Three important aspects considering the stability of a single armour layer of a breakwater consisting of concrete cubes are addressed: The influence of the wave steepness on the stqbility, the influence of the slope on the stability of the single armour layer, and the influence of the packing density on the stability of the single armour layer. This study is based on a literature study and the results from a test program including a small-scale physical model tests. All conclusions in this thesis have been based on model tests, in which the cubes were placed by hand and placed in a stretching bond (half-steensverband). In total eighteen tests were performed in the wave flume of the Fluid Mechanics Laboratory of the Faculty of Civil Engineering and Geosciences. Two different slopes were tested together with three different packing densities and three different wave steepness. It was found that the gentler slope did not contribute to the stability in this setting using a stretching bond. In fact the model failed earlier than the model with a steeper slope in most cases. The best results were found using a slope of cot? = 1.5. Secondly, the influence of the packing density showed varying failure mechanism. When applying a large packing density (np = 0.20) the damage occurred below SWL. Contrary to small packing densities (np = 0.35) where damage occurred higher than SWL. It was found that, from the tested packing densities, a packing density of 0.28 gives the best results for both slopes. This conclusion is conform the findings of previous tests [Van Gent et al, 1999]. During these tests an optimum packing density of np = 0.25 – 0.30 was found. Although the cubes were placed randomly in the tests of Van Gent. In this study the cubes were placed in a stretching bond. Finally it was found that a wave steepness of s0p = 0.04-0.05 causes minimum stability for the armour layer. The tests with a single armour layer of cubes placed in a stretching bond indicated that high sta-bility numbers (Hs/?Dn) can be reached before failure occurs (Nod > 0.2). the tests show that sta-bility numbers as high as 4.5 can be realized before Nod > 0.2 is reached. This study shows that the use of a single top layer of cubes is feasible. The top layer becomes very stable when placed in a stretching bond. In this configuration it is recommended to use a single top layer of cubes instead of a double top layer of cubes. The results during the tests seem to have a strong correlation with pitched stones. Therefore the black box model as well as the analytical method for pitched stones (6-xi-rule) is treated in an attempt to optimize the design rules for different configurations. Finally, in combination with an adjusted 6-xi-rule and the formulae from Van der Meer for loose rock, formulae were developed based on curve fitting.Hydraulic EngineeringCivil Engineering and Geoscience
MRI-based classification of neuropsychiatric systemic lupus erythematosus patients with self-supervised contrastive learning
No full textIntroduction/PurposeSystemic lupus erythematosus (SLE) is a chronic auto-immune disease with a broad spectrum of clinical presentations, including heterogeneous neuropsychiatric (NP) syndromes. Structural brain abnormalities are commonly found in SLE and NPSLE, but their role in diagnosis is limited, and their usefulness in distinguishing between NPSLE patients and patients in which the NP symptoms are not primarily attributed to SLE (non-NPSLE) is non-existent. Self-supervised contrastive learning algorithms proved to be useful in classification tasks in rare diseases with limited number of datasets. Our aim was to apply self-supervised contrastive learning on T-1-weighted images acquired from a well-defined cohort of SLE patients, aiming to distinguish between NPSLE and non-NPSLE patients. Subjects and MethodsWe used 3T MRI T-1-weighted images of 163 patients. The training set comprised 68 non-NPSLE and 34 NPSLE patients. We applied random geometric transformations between iterations to augment our data sets. The ML pipeline consisted of convolutional base encoder and linear projector. To test the classification task, the projector was removed and one linear layer was measured. Validation of the method consisted of 6 repeated random sub-samplings, each using a random selection of a small group of patients of both subtypes. ResultsIn the 6 trials, between 79% and 83% of the patients were correctly classified as NPSLE or non-NPSLE. For a qualitative evaluation of spatial distribution of the common features found in both groups, Gradient-weighted Class Activation Maps (Grad-CAM) were examined. Thresholded Grad-CAM maps show areas of common features identified for the NPSLE cohort, while no such communality was found for the non-NPSLE group. Discussion/ConclusionThe self-supervised contrastive learning model was effective in capturing common brain MRI features from a limited but well-defined cohort of SLE patients with NP symptoms. The interpretation of the Grad-CAM results is not straightforward, but indicates involvement of the lateral and third ventricles, periventricular white matter and basal cisterns. We believe that the common features found in the NPSLE population in this study indicate a combination of tissue loss, local atrophy and to some extent that of periventricular white matter lesions, which are commonly found in NPSLE patients and appear hypointense on T-1-weighted images.Radiolog
ASSESSMENT OF SEX‐RELATED METABOLIC DIFFERENCES IN A MOUSE MODEL OF ALZHEIMER'S DISEASE BY MRI
No full textSolid state NMR/Biophysical Organic Chemistr
- …
