| 1. |
- Axenhus, Michael, et al.
(author)
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Changes in dementia diagnoses in Sweden during the COVID-19 pandemic
- 2022
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In: BMC Geriatrics. - : BioMed Central. - 1471-2318 .- 1471-2318. ; 22:1
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Journal article (peer-reviewed)abstract
- Introduction: The COVID-19 pandemic has caused large disruptions to healthcare systems. Refocus on COVID-19 related care might have contributed to indirect effects on other healthcare areas. Care focused on acute conditions have been negatively affected although research into the effects on chronic and care intensive patient groups such as patients with dementia diseases is lacking. In this study we evaluated dementia diagnosis trends in Sweden during 2015–2020 according to International Classification of Disease version 10 coding of common dementia diseases.Methods: Regional and national statistics in the form of International Classification of Disease version 10 coding, COVID-19 incidence, mortality data, and population census data were collected from the National Institute of Health and Welfare. Logistic regression analysis was performed to identify trends of dementia diagnosis during 2015–2020. Correlation test was performed between COVID-19 incidence, mortality rates, and dementia coding.Results: Dementia diagnosis incidence has been declining since 2015 and further decline was noted in many regions in Sweden during 2020. As COVID-19 incidence increased, fewer cases of dementia were diagnosed, a decrease that differentially impacted women and those who were advanced in age.Conclusions: Dementia diagnosis incidence in Sweden has been on a decline since 2015. The COVID-19 pandemic caused a further larger decline in dementia diagnosis incidence during 2020. COVID-19 incidence, but not mortality, was associated with decrease in dementia diagnosis incidence. There might be a large number of undiagnosed patients with dementia and healthcare reforms should be enacted to address this. Women and elderly are particularly vulnerable groups.
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| 2. |
- Gao, Yang, et al.
(author)
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Live Cell FRET Imaging Reveals Amyloid beta-Peptide Oligomerization in Hippocampal Neurons
- 2021
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In: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 22:9
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Journal article (peer-reviewed)abstract
- Amyloid beta-peptide (A beta) oligomerization is believed to contribute to the neuronal dysfunction in Alzheimer disease (AD). Despite decades of research, many details of A beta oligomerization in neurons still need to be revealed. Forster resonance energy transfer (FRET) is a simple but effective way to study molecular interactions. Here, we used a confocal microscope with a sensitive Airyscan detector for FRET detection. By live cell FRET imaging, we detected A beta 42 oligomerization in primary neurons. The neurons were incubated with fluorescently labeled A beta 42 in the cell culture medium for 24 h. A beta 42 were internalized and oligomerized in the lysosomes/late endosomes in a concentration-dependent manner. Both the cellular uptake and intracellular oligomerization of A beta 42 were significantly higher than for A beta 40. These findings provide a better understanding of A beta 42 oligomerization in neurons.
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| 3. |
- Haytural, Hazal, et al.
(author)
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Insights into the changes in the proteome of Alzheimer disease elucidated by a meta-analysis
- 2021
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In: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 8:1
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Journal article (peer-reviewed)abstract
- Mass spectrometry (MS)-based proteomics is a powerful tool to explore pathogenic changes of a disease in an unbiased manner and has been used extensively in Alzheimer disease (AD) research. Here, by performing a meta-analysis of high-quality proteomic studies, we address which pathological changes are observed consistently and therefore most likely are of great importance for AD pathogenesis. We retrieved datasets, comprising a total of 21,588 distinct proteins identified across 857 postmortem human samples, from ten studies using labeled or label-free MS approaches. Our meta-analysis findings showed significant alterations of 757 and 1,195 proteins in AD in the labeled and label-free datasets, respectively. Only 33 proteins, some of which were associated with synaptic signaling, had the same directional change across the individual studies. However, despite alterations in individual proteins being different between the labeled and the label-free datasets, several pathways related to synaptic signaling, oxidative phosphorylation, immune response and extracellular matrix were commonly dysregulated in AD. These pathways represent robust changes in the human AD brain and warrant further investigation.
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| 4. |
- Lundgren, Jolanta L, et al.
(author)
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ADAM10 and BACE1 are localized to synaptic vesicles.
- 2015
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In: Journal of Neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 135:3, s. 606-615
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Journal article (peer-reviewed)abstract
- Synaptic degeneration and accumulation of the neurotoxic amyloid β-peptide (Aβ) in the brain are hallmarks of Alzheimer disease. Aβ is produced by sequential cleavage of its precursor protein, APP, by the β-secretase BACE1 and γ-secretase. However, Aβ generation is precluded if APP is cleaved by the α-secretase ADAM10 instead of BACE1. We have previously shown that Aβ can be produced locally at the synapse. To study the synaptic localization of the APP processing enzymes we used western blotting to demonstrate that, compared to total brain homogenate, ADAM10 and BACE1 were greatly enriched in synaptic vesicles isolated from rat brain using controlled-pore glass chromatography, whereas Presenilin1 was the only enriched component of the γ-secretase complex. Moreover, we detected ADAM10 activity in synaptic vesicles and enrichment of the intermediate APP-C-terminal fractions (APP-CTFs). We confirmed the western blotting findings using in situ proximity ligation assay to demonstrate close proximity of ADAM10 and BACE1 with the synaptic vesicle marker synaptophysin in intact mouse primary hippocampal neurons. In contrast, only sparse co-localization of active γ-secretase and synaptophysin was detected. These results indicate that the first step of APP processing occurs in synaptic vesicles whereas the final step is more likely to take place elsewhere. This article is protected by copyright. All rights reserved.
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| 5. |
- Schedin-Weiss, Sophia, et al.
(author)
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Super-resolution microscopy reveals gamma-secretase at both sides of the neuronal synapse
- 2016
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In: Acta neuropathologica communications. - : BioMed Central. - 2051-5960. ; 4
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Journal article (peer-reviewed)abstract
- The transmembrane protein assembly gamma-secretase is a key protease in regulated intramembrane processing (RIP) of around 100 type-1 transmembrane proteins. Importantly, it has a pathological role in Alzheimer disease (AD) as it generates the neurotoxic amyloid beta-peptide from the amyloid precursor protein (APP). Studies on gamma-secretase location are therefore crucial both from a biological and a therapeutic perspective. Despite several years of efforts in many laboratories, it is not clear where in the neuron gamma-secretase exerts it's activities. Technical challenges include the fact that the active enzyme contains four protein components and that most subcellular compartments cannot be spatially resolved by traditional light microscopy. Here, we have used a powerful combination of the two nanoscopy techniques STORM and STED microscopy to visualize the location of gamma-secretase in neurons using an active-site specific probe, with a focus on the synapse. We show that gamma-secretase is present in both the pre-and postsynaptic compartments. We further show that the enzyme is enriched very close to the synaptic cleft in the postsynaptic membrane, as well as to NMDA receptors, demonstrating that gamma-secretase is present in the postsynaptic plasma membrane. Importantly, the expression of gamma-secretase increased in the pre-and postsynaptic compartments with the size of the synapse, suggesting a correlation between gamma-secretase activity and synapse maturation. Thus, our data shows the synaptic location with high precision in three dimensions and settles the long-lasting debate on the synaptic location of gamma-secretase.
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| 6. |
- Yu, Yang, et al.
(author)
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Neuronal A beta 42 is enriched in small vesicles at the presynaptic side of synapses
- 2018
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In: Life Science Alliance. - : LIFE SCIENCE ALLIANCE LLC. - 2575-1077. ; 1:3
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Journal article (peer-reviewed)abstract
- The amyloid beta-peptide (A beta) is a physiological ubiquitously expressed peptide suggested to be involved in synaptic function, long-term potentiation, and memory function. The 42 amino acid-long variant (A beta 42) forms neurotoxic oligomers and amyloid plaques and plays a key role in the loss of synapses and other pathogenic events of Alzheimer disease. Still, the exact localization of A beta 42 in neurons and at synapses has not been reported. Here, we used super-resolution microscopy and show that A beta 42 was present in small vesicles in presynaptic compartments, but not in postsynaptic compartments, in the neurites of hippocampal neurons. Some of these vesicles appeared to lack synaptophysin, indicating that they differ from the synaptic vesicles responsible for neurotransmitter release. The A beta 42-containing vesicles existed in presynapses connected to stubby spines and mushroom spines, and were also present in immature presynapses. These vesicleswere scarce inother parts of the neurites, where A beta 42 was instead present in large, around 200-600 nm, vesicular structures. Three-dimensional super-resolution microscopy confirmed that A beta 42 was present in the presynapse and absent in the postsynapse.
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| 7. |
- Zhou, Robin Ziyue, et al.
(author)
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A glycan epitope correlates with tau in serum and predicts progression to Alzheimer's disease in combination with APOE4 allele status
- 2023
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In: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:7, s. 3244-3249
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Journal article (peer-reviewed)abstract
- INTRODUCTION: There is an urgent need for novel blood biomarkers for the detection of Alzheimer's disease (AD). We previously showed that levels of the bisecting N-acetylglucosamine glycan epitope was elevated in cerebrospinal fluid in AD. However, its diagnostic value in blood is unknown.METHODS: We analyzed blood levels of bisecting N-acetylglucosamine and total tau in a retrospective cohort of 233 individuals. Progression to AD was compared between the groups using Cox regression. The predictive value of the biomarkers was determined by logistic regression.RESULTS: Bisecting N-acetylglucosamine correlated with tau levels (p < 0.0001). Individuals with an intermediate tau/bisecting N-acetylglucosamine ratio had elevated AD risk (hazard ratio = 2.06, 95% confidence interval [CI]: 1.18–3.6). Moreover, a combined model including tau/bisecting N-acetylglucosamine ratio, apolipoprotein E (APOE) ε4 status, and Mini-Mental State Examination score predicted future AD (area under the curve = 0.81, 95% CI: 0.68–0.93).DISCUSSION: Bisecting N-acetylglucosamine in combination with tau is a valuable blood biomarker for predicting AD.
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