Counsellors' perceptions of psychological empowerment through a lay counselling service in a disadvantaged community.

The aim of this qualitative study was to explore the perceptions of a group of lay counsellors about their psychological empowerment. It was hypothesised that the counsellors were empowered as a result of their involvement in a counselling service, within the context of a disadvantaged community. Five out of a potential seven participants consented to be interviewed. The researcher used a semi-structured interview schedule to guide the interview process and thematic content analysis was used to analyse the data. The themes that emerged from the analysis related to the components of psychological empowerment as postulated by Zimmerman (1995), as well as the participants’ experience within the counselling service. The study concluded that the participants experienced becoming psychologically empowered, which led to improvements within their own lives. Despite this empowerment, the participants did not appear to be enabled to influence the removal of structural barriers that cause social inequities within their communities. The study concluded that this appeared to be as a result of constraints linked to psychological empowerment. In addition, the study found that the counselling service experienced many difficulties that are similar to those experienced by many other organisations that attempt to conduct community work within the South African context

An automated pipeline for extracting histological stain area fraction for voxelwise quantitative MRI-histology comparisons

The acquisition of MRI and histology in the same post-mortem tissue sample enables direct correlation between MRI and histologically-derived parameters. However, there still lacks a standardised automated pipeline to process histology data, with most studies relying on manual intervention. Here, we introduce an automated pipeline to extract a quantitative histological measure for staining density (stain area fraction, SAF) from multiple immunohistochemical (IHC) stains. The pipeline is designed to directly address key IHC artefacts related to tissue staining and slide digitisation. Here, the pipeline was applied to post-mortem human brain data from multiple subjects, relating MRI parameters (FA, MD, RD, AD, R2*, R1) to IHC slides stained for myelin, neurofilaments, microglia and activated microglia. Utilising high-quality MRI-histology co-registrations, we then performed whole-slide voxelwise comparisons (simple correlations, partial correlations and multiple regression analyses) between multimodal MRI- and IHC-derived parameters. The pipeline was found to be reproducible, robust to artefacts and generalisable across multiple IHC stains. Our partial correlation results suggest that some simple MRI-SAF correlations should be interpreted with caution, due to the co-localisation of other tissue features (e.g., myelin and neurofilaments). Further, we find activated microglia—a generic biomarker of inflammation—to consistently be the strongest predictor of high DTI FA and low RD, which may suggest sensitivity of diffusion MRI to aspects of neuroinflammation related to microglial activation, even after accounting for other microstructural changes (demyelination, axonal loss and general microglia infiltration). Together, these results show the utility of this approach in carefully curating IHC data and performing multimodal analyses to better understand microstructural relationships with MRI

Voxel-wise comparisons of cellular microstructure and diffusion-MRI in mouse hippocampus using 3D Bridging of Optically-clear histology with Neuroimaging Data (3D-BOND)

A key challenge in medical imaging is determining a precise correspondence between image properties and tissue microstructure. This comparison is hindered by disparate scales and resolutions between medical imaging and histology. We present a new technique, 3D Bridging of Optically-clear histology with Neuroimaging Data (3D-BOND), for registering medical images with 3D histology to overcome these limitations. Ex vivo 120 × 120 × 200 μm resolution diffusion-MRI (dMRI) data was acquired at 7 T from adult C57Bl/6 mouse hippocampus. Tissue was then optically cleared using CLARITY and stained with cellular markers and confocal microscopy used to produce high-resolution images of the 3D-tissue microstructure. For each sample, a dense array of hippocampal landmarks was used to drive registration between upsampled dMRI data and the corresponding confocal images. The cell population in each MRI voxel was determined within hippocampal subregions and compared to MRI-derived metrics. 3D-BOND provided robust voxel-wise, cellular correlates of dMRI data. CA1 pyramidal and dentate gyrus granular layers had significantly different mean diffusivity (p > 0.001), which was related to microstructural features. Overall, mean and radial diffusivity correlated with cell and axon density and fractional anisotropy with astrocyte density, while apparent fibre density correlated negatively with axon density. Astrocytes, axons and blood vessels correlated to tensor orientation

An open resource combining multi-contrast MRI and microscopy in the macaque brain

Understanding brain structure and function often requires combining data across different modalities and scales to link microscale cellular structures to macroscale features of whole brain organisation. Here we introduce the BigMac dataset, a resource combining in vivo MRI, extensive postmortem MRI and multi-contrast microscopy for multimodal characterisation of a single whole macaque brain. The data spans modalities (MRI and microscopy), tissue states (in vivo and postmortem), and four orders of spatial magnitude, from microscopy images with micrometre or sub-micrometre resolution, to MRI signals on the order of millimetres. Crucially, the MRI and microscopy images are carefully co-registered together to facilitate quantitative multimodal analyses. Here we detail the acquisition, curation, and first release of the data, that together make BigMac a unique, openly-disseminated resource available to researchers worldwide. Further, we demonstrate example analyses and opportunities afforded by the data, including improvement of connectivity estimates from ultra-high angular resolution diffusion MRI, neuroanatomical insight provided by polarised light imaging and myelin-stained histology, and the joint analysis of MRI and microscopy data for reconstruction of the microscopy-inspired connectome. All data and code are made openly available

Application of European Society of Cardiology guidelines for evaluating acute coronary syndrome risk in low-risk patients with cocaine-associated chest pain: Findings from the RISK study – An observational analysis

Background: Cocaine was the drug of choice in 4.7 % of all recreational drug-related emergency department visits. Of these patients, 40 % present with cocaine-associated chest pain, of whom 4.7 % develop an acute coronary syndrome. The American Heart Association recommends a 12-hour observation period for these patients. Objective: This study primarily aimed to ascertain whether the European Society of Cardiology non-ST-elevation myocardial infarction guidelines can be safely applied to rule-out acute coronary syndrome in low-risk patients with cocaine-associated chest pain. Methods: For this prospective observational cohort study, patients, aged 18–45 years old, who presented with cocaine-associated chest pain and were risk stratified as low risk according to the European Society of Cardiology non-ST-elevation myocardial infarction guidelines and therefore discharged home without prolonged observation period, were included. They were followed to assess major adverse cardiac events four weeks after presentation to the emergency department or chest pain unit. Cocaine use was confirmed with urine toxicology screening. Results: A total of 107 patients were included and analysed. The accuracy of the self-reported history of recent cocaine use was 94 %. Post-discharge cocaine use persisted among 32 % of patients. None of the included 107 patients died and major adverse cardiac event within four weeks did not occur among 97 patients with available data regarding MACE. Conclusion: Ruling out an acute coronary syndrome using the European Society of Cardiology non-ST-elevation myocardial infarction guidelines is likely to be safe for patients with cocaine-associated chest pain, however this study was underpowered to reach definitive conclusions

Estimating axial diffusivity in the NODDI model

To estimate microstructure-related parameters from diffusion MRI data, biophysical models make strong, simplifying assumptions about the underlying tissue. The extent to which many of these assumptions are valid remains an open research question. This study was inspired by the disparity between the estimated intra-axonal axial diffusivity from literature and that typically assumed by the Neurite Orientation Dispersion and Density Imaging (NODDI) model ( d ∥ = 1.7 μ m 2 /ms ). We first demonstrate how changing the assumed axial diffusivity results in considerably different NODDI parameter estimates. Second, we illustrate the ability to estimate axial diffusivity as a free parameter of the model using high b-value data and an adapted NODDI framework. Using both simulated and in vivo data we investigate the impact of fitting to either real-valued or magnitude data, with Gaussian and Rician noise characteristics respectively, and what happens if we get the noise assumptions wrong in this high b-value and thus low SNR regime. Our results from real-valued human data estimate intra-axonal axial diffusivities of ∼ 2 − 2.5 μ m 2 /ms , in line with current literature. Crucially, our results demonstrate the importance of accounting for both a rectified noise floor and/or a signal offset to avoid biased parameter estimates when dealing with low SNR data

Evaluating fibre orientation dispersion in white matter: comparison of diffusion MRI, histology and polarized light imaging

Diffusion MRI is an exquisitely sensitive probe of tissue microstructure, and is currently the only non-invasive measure of the brain’s fibre architecture. As this technique becomes more sophisticated and microstructurally informative, there is increasing value in comparing diffusion MRI with microscopic imaging in the same tissue samples. This study compared estimates of fibre orientation dispersion in white matter derived from diffusion MRI to reference measures of dispersion obtained from polarized light imaging and histology. Three post-mortem brain specimens were scanned with diffusion MRI and analyzed with a two-compartment dispersion model. The specimens were then sectioned for microscopy, including polarized light imaging estimates of fibre orientation and histological quantitative estimates of myelin and astrocytes. Dispersion estimates were correlated on region – and voxel-wise levels in the corpus callosum, the centrum semiovale and the corticospinal tract. The region-wise analysis yielded correlation coefficients of r=0.79 for the diffusion MRI and histology comparison, while r=0.60 was reported for the comparison with polarized light imaging. In the corpus callosum, we observed a pattern of higher dispersion at the midline compared to its lateral aspects. This pattern was present in all modalities and the dispersion profiles from microscopy and diffusion MRI were highly correlated. The astrocytes appeared to have minor contribution to dispersion observed with diffusion MRI. These results demonstrate that fibre orientation dispersion estimates from diffusion MRI represents the tissue architecture well. Dispersion models might be improved by more faithfully incorporating an informed mapping based on microscopy data

The preventive medicine

The project is all about the relevant topic of (the lack of) phisical movement in society. The link between health and architecture has always interested me, in this project these two topics come together to give an answer on the future dwellings in the Netherlands.Architecture, Urbanism and Building Sciences | Dwellin

Multiscale imaging of white matter microstructure

Contains fulltext : 204271.pdf (publisher's version ) (Open Access)Radboud University, 25 juni 2019Promotores : Kozicz, L.T., Miller, K.L. Co-promotores : Cappellen van Walsum, A.M. van, Kleinnijenhuis, M