| 1. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 2. |
- Ahl, Matilda, et al.
(författare)
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Inflammatory reaction in the retina after focal non-convulsive status epilepticus in mice investigated with high resolution magnetic resonance and diffusion tensor imaging
- 2021
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Ingår i: Epilepsy Research. - : Elsevier. - 0920-1211 .- 1872-6844. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- Pathophysiological consequences of focal non-convulsive status epilepticus (fNCSE) have been difficult to demonstrate in humans. In rats fNCSE pathology has been identified in the eyes. Here we evaluated the use of high-resolution 7 T structural T1-weighted magnetic resonance imaging (MRI) and 9.4 T diffusion tensor imaging (DTI) for detecting hippocampal fNCSE-induced retinal pathology ex vivo in mice. Seven weeks post-fNCSE, increased number of Iba1+ microglia were evident in the retina ipsilateral to the hemisphere with fNCSE, and morphologically more activated microglia were found in both ipsi- and contralateral retina compared to non-stimulated control mice. T1-weighted intensity measurements of the contralateral retina showed a minor increase within the outer nuclear and plexiform layers of the lateral retina. T1-weighted measurements were not performed in the ipsilateral retina due to technical difficulties. DTI fractional anisotropy(FA) values were discretely altered in the lateral part of the ipsilateral retina and unaltered in the contralateral retina. No changes were observed in the distal part of the optic nerve. The sensitivity of both imaging techniques for identifying larger retinal alteration was confirmed ex vivo in retinitis pigmentosa mice where a substantial neurodegeneration of the outer retinal layers is evident. With MR imaging a 50 % decrease in DTI FA values and significantly thinner retina in T1-weighted images were detected. We conclude that retinal pathology after fNCSE in mice is subtle and present bilaterally. High-resolution T1-weighted MRI and DTI independently did not detect the entire pathological retinal changes after fNCSE, but the combination of the two techniques indicated minor patchy structural changes.
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| 3. |
- Avdic, Una, et al.
(författare)
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Nonconvulsive status epilepticus in rats leads to brain pathology
- 2018
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Ingår i: Epilepsia. - : Wiley. - 0013-9580 .- 1528-1167. ; 59:5, s. 945-958
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Status epilepticus (SE) is an abnormally prolonged epileptic seizure that if associated with convulsive motor symptoms is potentially life threatening for a patient. However, 20%-40% of patients with SE lack convulsive events and instead present with more subtle semiology such as altered consciousness and less motor activity. Today, there is no general consensus regarding to what extent nonconvulsive SE (NCSE) is harmful to the brain, which adds uncertainty to stringent treatment regimes. Methods: Here, we evaluated brain pathology in an experimental rat and mouse model of complex partial NCSE originating in the temporal lobes with Western blot analysis, immunohistochemistry, and ex vivo diffusion tensor imaging (DTI). The NCSE was induced by electrical stimulation with intrahippocampal electrodes and terminated with pentobarbital anesthesia. Video-electroencephalographic recordings were performed throughout the experiment. Results: DTI of mice 7 weeks post-NCSE showed no robust long-lasting changes in fractional anisotropy within the hippocampal epileptic focus. Instead, we found pathophysiological changes developing over time when measuring protein levels and cell counts in extracted brain tissue. At 6 and 24 hours post-NCSE in rats, few changes were observed within the hippocampus and cortical or subcortical structures in Western blot analyses of key components of the cellular immune response and synaptic protein expression, while neurodegeneration had started. However, 1 week post-NCSE, both excitatory and inhibitory synaptic protein levels were decreased in hippocampus, concomitant with an excessive microglial and astrocytic activation. At 4 weeks, a continuous immune response in the hippocampus was accompanied with neuronal loss. Levels of the excitatory synaptic adhesion molecule N-cadherin were decreased specifically in rats that developed unprovoked spontaneous seizures (epileptogenesis) within 1 month following NCSE, compared to rats only exhibiting acute symptomatic seizures within 1 week post-NCSE. Significance: These findings provide evidence for a significant brain pathology following NCSE in an experimental rodent model.
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| 4. |
- Beháňová, Andrea, et al.
(författare)
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gACSON software for automated segmentation and morphology analyses of myelinated axons in 3D electron microscopy
- 2022
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Ingår i: Computer Methods and Programs in Biomedicine. - : Elsevier. - 0169-2607 .- 1872-7565. ; 220
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Tidskriftsartikel (refereegranskat)abstract
- Background and Objective: Advances in electron microscopy (EM) now allow three-dimensional (3D) imaging of hundreds of micrometers of tissue with nanometer-scale resolution, providing new opportunities to study the ultrastructure of the brain. In this work, we introduce a freely available Matlab-based gACSON software for visualization, segmentation, assessment, and morphology analysis of myelinated axons in 3D-EM volumes of brain tissue samples.Methods: The software is equipped with a graphical user interface (GUI). It automatically segments the intra-axonal space of myelinated axons and their corresponding myelin sheaths and allows manual segmentation, proofreading, and interactive correction of the segmented components. gACSON analyzes the morphology of myelinated axons, such as axonal diameter, axonal eccentricity, myelin thickness, or gratio.Results: We illustrate the use of the software by segmenting and analyzing myelinated axons in six 3DEM volumes of rat somatosensory cortex after sham surgery or traumatic brain injury (TBI). Our results suggest that the equivalent diameter of myelinated axons in somatosensory cortex was decreased in TBI animals five months after the injury.Conclusion: Our results indicate that gACSON is a valuable tool for visualization, segmentation, assessment, and morphology analysis of myelinated axons in 3D-EM volumes. It is freely available at https://github.com/AndreaBehan/g-ACSON under the MIT license.
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| 5. |
- Narvaez, Omar, et al.
(författare)
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Massively Multidimensional Diffusion-Relaxation Correlation MRI
- 2022
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Ingår i: Frontiers in Physics. - : Frontiers Media SA. - 2296-424X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Diverse approaches such as oscillating gradients, tensor-valued encoding, and diffusion-relaxation correlation have been used to study microstructure and heterogeneity in healthy and pathological biological tissues. Recently, acquisition schemes with free gradient waveforms exploring both the frequency-dependent and tensorial aspects of the encoding spectrum b(ω) have enabled estimation of nonparametric distributions of frequency-dependent diffusion tensors. These “D(ω)-distributions” allow investigation of restricted diffusion for each distinct component resolved in the diffusion tensor trace, anisotropy, and orientation dimensions. Likewise, multidimensional methods combining longitudinal and transverse relaxation rates, R1 and R2, with (ω-independent) D-distributions capitalize on the component resolution offered by the diffusion dimensions to investigate subtle differences in relaxation properties of sub-voxel water populations in the living human brain, for instance nerve fiber bundles with different orientations. By measurements on an ex vivo rat brain, we here demonstrate a “massively multidimensional” diffusion-relaxation correlation protocol joining all the approaches mentioned above. Images acquired as a function of the magnitude, normalized anisotropy, orientation, and frequency content of b(ω), as well as the repetition time and echo time, yield nonparametric D(ω)-R1-R2-distributions via a Monte Carlo data inversion algorithm. The obtained per-voxel distributions are converted to parameter maps commonly associated with conventional lower-dimensional methods as well as unique statistical descriptors reporting on the correlations between restriction, anisotropy, and relaxation.
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