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- Andreasson, U., et al.
(författare)
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An enzyme activity as a potential biomarker for Alzheimer's disease.
- 2010
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5279 .- 1552-5260. ; 6:4, s. 497-498
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Konferensbidrag (refereegranskat)abstract
- Background: Six different N-terminal amyloid precursor protein (APP) fragments, with molecular weight ∼12 kDa, have previously been identified in human cerebrospinal fluid (CSF). In a pilot study, both the sum of their concentrations, measured by western blot, and the relative abundance pattern, measured by mass spectrometry, were different in Alzheimer's disease (AD) patients compared to healthy controls. To test if these differences were also reflected in protease activities that possibly give rise to the ∼12 kDa fragments an enzymatic assay was developed and the activity in CSF was investigated for its potential as a biomarker for AD. Methods: The substrate in the protease activity assay was a custom made fluorochrome/quencher labeled peptide that covers the cleavage sites in APP (APP118-APP127) corresponding to the C-termini of the six ∼12 kDa APP fragments. The activity was measured in CSF from 55 AD patients and 17 controls. Results: There was a significant increase in the protease activity in CSF from AD patients compared to the controls (p = 0.001). This is in line with previous results which indicate that the sum of the ∼12 kDa fragments are elevated in AD. Results from inhibition studies strongly suggests that the enzyme responsible for the cleavage of the substrate is an aspartic protease since a sub nM IC50 value was recorded for Pepstatin A while no inhibition was observed for the cysteine protease specific inhibitor E64 at concentrations up to100 nM. Conclusions: There exists an enzymatic activity in CSF capable of cleaving a peptide substrate that spans a portion, close to the N-terminal, of APP. In a pilot study the activity is increased in AD patients compared to controls suggesting that it can be used as a biomarker.
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- Johansson, Per, et al.
(författare)
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Convergence of chromogranin and amyloid metabolism in the brain.
- 2010
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5279 .- 1552-5260. ; 6:4, s. 511-511
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Konferensbidrag (refereegranskat)abstract
- Background: Much is unknown regarding the regulation of amyloid precursor protein (APP) processing in the human central nervous system. It has been hypothesized that amyloidogenic APP-processing preferentially occurs in the regulated secretory pathway of neurons. To test this hypothesis we looked for correlations of APP-derived molecules in CSF with chromogranin (Cg) derived peptides, representing the regulated secretion. Methods: Patients with Alzheimer's disease (AD, N = 32), multiple sclerosis (MS, N = 50) and healthy controls (N = 70) were enrolled. CSF was analyzed for the amyloid peptides Aβ1-42, Aβx-42, Aβx-40, Aβx-38, α-cleaved soluble APP (α-sAPP), β-cleaved soluble APP (β-sAPP), and peptides derived from CgB and SgII (Secretogranin-II, CgC). We investigated CSF levels of the protease BACE1, which processes APP into Aβ, in relation to Cg-levels. Finally, we measured Cg levels in cell media from untreated and BACE1-inhibited SH-SY5Y human neuroblastoma cells. Results: CSF Cg levels correlated to sAPP and Aβ peptides in AD, MS and controls, and to CSF BACE1. Cell medium from BACE1-inhibited cells had decreased CgB levels. Conclusions: These results suggest that a large part of APP in the human central nervous system is processed in the regulated secretory pathway of neurons.
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| 4. |
- Smith, Ruben, et al.
(författare)
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18F-AV1451 pet detects tau pathology in mapt mutation carriers and correlates strongly with immunohistochemistry of tau aggregates
- 2016
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5279 .- 1552-5260. ; 12:7 Suppl, s. 723-724
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Konferensbidrag (refereegranskat)abstract
- Background: The Tau PET ligand 18F-AV1451 has been shown to reliably detect paired helical filaments of tau in Alzheimer's disease, but it is not yet known whether it binds to the tau aggregates present in patients with mutations in the gene (MAPT) coding for the tau protein. Further, no study has yet compared the cerebral retention of 18F -AV1451 with the tau aggregates revealed using neuropathology. Methods: Three patients from a Swedish family carrying the R406W mutation of MAPT were assessed with cognitive tests and subjects underwent 18F-AV1451 and 18F-Flutemetamol PET scans. Further one of younger subjects also underwent an 18F-FDG PET scan. The oldest subject died two weeks after the scan and the brain was processed for neuropathology. Tau immunohistochemistry was performed on brain sections from affected and unaffected brain regions. Results: Two mutation carriers, aged 56 and 60 years, had disease durations of 5-10 years and still only exhibited mild-moderate episodic memory impairment and no clear behavioural deficits. The MRI revealed only slight cortical atrophy and 18F-AV1451 PET imaging showed uptake in the hippocampus and the temporal lobes, especially in the inferior and anterior parts (Fig 1A, B). The uptake of 18F - AV1451 correlated well with hypometabolism revealed with FGD PET in one of the subjects. The third case, 76 years, had a disease duration of ≥20 years and exhibited clear cognitive impairment, behavioural disturbances, mutism and dysphagia. The CT scan showed generalised cortical atrophy with a pronounced temporal lobe atrophy and 18F -AV1451 PET imaging revealed uptake in the temporal and frontal lobes, as well as in the basal ganglia (Fig 1 C). The regional uptake of 18F -AV1451 correlated strongly with the tau aggregates revealed using immunohistochemistry (R2 = 0.80, P <0.01; Fig 2). All cases exhibited negative amyloid (18F -flutemetamol) PET scans. Conclusions: The in vivo uptake of 18F-AV1451 reflects the regional amount of tau aggregates revealed by neuropathological examination. Further, tau pathology in MAPT mutation carriers is accurately detected with 18F -AV1451 PET, which consequently can be used to track the effects of anti-tau therapies in this patient group. (Figure Presented) .
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| 5. |
- Zahirovic, Iris, et al.
(författare)
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Prevalence of Lewy body dementia and neuroleptic treatment in nursing homes in Malmö, Sweden.
- 2014
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Lewy body Dementia (LBD) is a well-known neurocognitive disorder in the elderly. The hallmarks of LBD are Parkinsonism without tremor, recurrent and persistent visual hallucinations often with insight, fluctuating cognition and alertness, rapid eye movement (REM) sleep behavior disorder with vivid dreams and violent movements, but relatively preserved memory functions. Nevertheless, LBD is often misdiagnosed and under-recognized. A diagnosis of LBD is important because of the risk of hypersensitivity for neuroleptic drugs. Moreover, appropriate treatment of symptoms can improve quality of life considerably for both the individual with LBD and their caregivers. This study aimed to investigate the prevalence of possible LBD and neuroleptic treatment in elderly care recipients in nursing homes. Methods: Information regarding prevalence of symptoms of LBD and concurrent medication in 644 elderly living in nursing homes in Malmö, Sweden during the time period 2012-13 was collected. We used a questionnaire, medical journals and interviewed the nursing staff. In the questionnaire, symptoms representing the 4 LBD main characteristics were noted as present/absent; Parkinsonism, visual hallucinations, excessive daytime sleepiness, acting out dreams. Neuroleptic treatment was also noted as present or not, as well as the type of drug. Results: In total, 27.3% had_2 of 4 LBD symptoms. 7.1% had 3, and 3.0% had 4 of these symptoms. Visual hallucinations were observed in 20% and REM sleep behaviour disorder in 9% of the patients. Neuroleptic treatment increased significantly (p<0.001) with increasing number of LBD symptoms. In individuals with no symptoms 12.8%, 1 symptom 24.7%, 2 symptoms 26.9%, 3 symptoms 28.9%, and 4 symptoms 42.1% were treated with neuroleptics. Nine percent of the neuroleptics prescribed were of acceptable type (klozapin, quetiapin). Conclusions: Symptoms consistent with LBD are common in elderly in nursing homes. Despite the recommendations of avoiding neuroleptic treatment this was a common finding among the studied individuals. To minimize inappropriate medical treatment recognizing symptoms of LBD are important for general practitioners.
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| 6. |
- Konings, Sabine C., et al.
(författare)
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Neurobiological role of Alzheimer's disease genetic risk factor ApoE on early synaptic changes in Alzheimer-like models
- 2021
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Ingår i: Alzheimer's & dementia : the journal of the Alzheimer's Association. - 1552-5279. ; 17:S3, s. 1-1
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Konferensbidrag (refereegranskat)abstract
- BACKGROUND: The presence of an apolipoprotein E4 (ApoE4) genotype is the major genetic risk factor for Alzheimer's disease (AD). Astrocytes are the main source of ApoE in the brain, however ApoE can also be produced by neurons and microglia. ApoE plays a role in many cell types and processes related to AD, however, it remains unclear which mechanism(s) and cellular source of ApoE are most critical for AD. One of the earliest changes in AD are early cellular changes such as endosomal and synaptic alterations. ApoE4 has been associated with impaired endosomal trafficking and dysregulated synaptic plasticity. Neuronal hyperexcitability has been reported in mice expressing human ApoE4, a dysregulation that is also seen in AD transgenic mice. Although ApoE seems to play a crucial role in neuronal changes linked to early AD, ApoE's synaptic localization and mechanisms remain poorly understood. In this study, the aim is to determine the role of ApoE, in particular ApoE4, on synaptic alterations in AD models. METHOD: Mouse neurons and astrocytes are derived from wild-type, ApoE knock-out (KO), humanized ApoE3 and ApoE4 knock-in mice. Astrocyte-conditioned medium from mouse astrocytes expressing human ApoE and recombinant ApoE are used as a source for human ApoE to treat ApoE KO, wild-type and AD transgenic APP/PS1 neurons. Additionally, ApoE KO and humanized ApoE neurons are treated with synthetic Aβ or vehicle control. Analysis is performed using immunofluorescence, confocal and live cell imaging. RESULT: Exogenously added and endogenously produced human ApoE is shown to be present at neurites and synaptic terminals of cultured neurons. Differences in neuronal activity are observed among different ApoE conditions using Ca2+ live cell microscopy, both in the presence and absence of elevated human Aβ. Added recombinant and endogenous ApoE appear to be present in the endosome-lysosome system of neurons. CONCLUSION: ApoE appears to localize at synapses and endosomes, sites associated with early cellular changes in AD, and seems to play a role in neuronal excitability. Determining the neurobiology of ApoE, in particular in connection with cellular sites vulnerable to early changes in AD, can contribute to a better understanding of the role of ApoE in AD.
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