| 238601. |
- Smith, Ruben, et al.
(författare)
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Correlation of in Vivo [18F]Flortaucipir with Postmortem Alzheimer Disease Tau Pathology
- 2019
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Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149. ; 76:3, s. 310-310
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Tidskriftsartikel (refereegranskat)abstract
- Importance: In Alzheimer disease (AD), tau filaments form neuronal inclusions in neurites (neuropil threads) and in somata (neurofibrillary tangles), and neurite tau pathology constitutes the most common pathology. Positron emission tomography (PET) ligands have been developed to detect in vivo tau pathology in AD. However, the association of AD tau pathology post mortem with in vivo tau PET retention has not been established. Therefore, there is a need to investigate the associations of tau PET with postmortem tau pathology in AD. Objective: To study the association of regional in vivo retention of the tau PET ligand [18F]flortaucipir (previously known as AV1451) with the density of tau neuropathology in the corresponding brain regions in a patient with AD. Design, Setting, and Participants: The patient was a man in his 40s with AD caused by a PSEN1 mutation. Between May 2015 and December 2016, he underwent 2 [18F]flortaucipir PET scans at Lund University Hospital, Lund, Sweden. Postmortem analysis was performed 12 months after the last PET scan. Tau pathology was assessed using phosphorylated tau (AT8) immunohistochemistry and Gallyas silver staining. In addition to the regional total tau pathology burden, the density of tau-positive neurites and intrasomal tau tangles were quantified using a stereology-based method. Further, β-amyloid-containing plaques were detected using 4G8 immunohistochemistry. Data were analyzed between January 2018 and August 2018. Main Outcomes and Measures: Regional standardized uptake value ratios of [18F]flortaucipir were compared with the amount of tau pathology in the corresponding brain areas. Results: In this patient, the clinical disease symptoms progressed rapidly in life, paralleled with an annual increase of tau PET retention of 20% to 40% in many cortical regions. Compared with postmortem immunohistochemistry, regional in vivo uptake of [18F]flortaucipir was correlated with the density of tau-positive neurites (AT8: rs = 0.87; P <.001; Gallyas: rs = 0.92; P <.001), intrasomal tau tangles (AT8: rs = 0.65; P =.01; Gallyas: rs = 0.84; P <.001), and total tau burden (AT8: rs = 0.84; P <.001; Gallyas: rs = 0.82; P <.001). No correlations between [18F]flortaucipir and β-amyloid pathology were found. Conclusions and Relevance: These results indicate that [18F]flortaucipir PET retention is a robust in vivo measure of the total AD tau burden.
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| 238602. |
- Smith, Ruben, et al.
(författare)
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Depletion of rabphilin 3A in a transgenic mouse model (R6/1) of Huntington's disease, a possible culprit in synaptic dysfunction.
- 2005
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 20:3, s. 673-684
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease (HD) is a hereditary neurodegenerative disorder characterized by progressive psychiatric, cognitive, and motor disturbances. We studied the expression of synaptic vesicle proteins in the R6/1 transgenic mouse model of HD. We observed that the levels of rabphilin 3A, a protein involved in exocytosis, is substantially decreased in synapses of most brain regions in R6/1 mice. The appearance of the reduction coincides with the onset of motor deficits and behavioral disturbances. Double immunohistochemistry did not show colocalization between rabphilin 3A and huntingtin aggregates in the HD mice. Using in situ hybridization, we demonstrated that rabphilin 3A mRNA expression was substantially reduced in the R6/1 mouse cortex compared to wild-type mice. Our results indicate that a decrease in mRNA levels underlie the depletion of protein levels of rabphilin 3A, and we suggest that this reduction may be involved in causing impaired synaptic transmission in R6/1 mice.
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| 238603. |
- Smith, RN, et al.
(författare)
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Enamel defects in extracted and exfoliated teeth from patients with Amelogenesis Imperfecta, measured using the extended enamel defects index and image analysis
- 2008
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Ingår i: Archives of Oral Biology. - Oxford : Pergamon Press. - 0003-9969 .- 1879-1506. ; 54:Suppl 1, s. S86-S92
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To enhance the phenotypic description and quantification of enamel defects from a North Sweden sample of extracted and exfoliated teeth originating from families with Amelogenesis Imperfecta by use of the extended enamel defects index (EDI) and image analysis to demonstrate the comparable reliability and value of the additional measurements.METHODS AND RESULTS: The sample comprised 109 deciduous and 7 permanent teeth from 32 individuals of 19 families with Amelogenesis Imperfecta in Northern Sweden. A special holder for individual teeth was designed and the whole sample was examined using the extended EDI and an image analysis system. In addition to the extended EDI definitions, the calibrated images were measured for tooth surface area, defect area and percentage of surface affected using image analysis techniques. The extended EDI was assessed using weighted and unweighted Kappa statistics. The reliability of imaging and measurement was determined using Fleiss' intra-class correlation coefficient (ICCC). Kappa values indicated good or excellent intra-operator repeatability and inter-operator reproducibility for the extended EDI. The Fleiss ICCC values indicated excellent repeatability for the image analysis measurements. Hypoplastic pits on the occlusal surfaces were the most frequent defect in this sample (82.6%). The occlusal surface displayed the most post-eruptive breakdown (39.13%) whilst the incisal portion of the buccal surfaces showed most diffuse opacities (53.4%). Image analysis methods demonstrated the largest mean hypoplastic pit areas were on the lingual surfaces. The largest mean post-eruptive breakdown areas were on the lingual surfaces of posterior teeth. The largest mean demarcated opacity areas were found on the labial surfaces.CONCLUSIONS: The extended EDI and the standardised image acquisition and analysis system provided additional information to conventional measurement techniques. Additional phenotypic variables were described.
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| 238604. |
- Smith, Ruben, et al.
(författare)
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Fria radikaler och sjuka proteiner - bovarna bakom Parkinsons sjukdom?[Free radicals and ailing proteins - the culprits behind Parkinson’s disease?]
- 2003
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Ingår i: Läkartidningen. - 0023-7205. ; 100:15, s. 6-1329
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Tidskriftsartikel (refereegranskat)abstract
- Parkinson’s disease is one of the most common neurodegenerative diseases, and affects approximately 1% of the population over 65 years of age. Many different insults appear to be involved in the etiology of the disease, among them environmental toxins and mitochondrial dysfunction. During the past five years, mutations in five different genes have been linked to rare, familial forms of Parkinson’s disease. One of the mutated proteins, a-synuclein is normally implicated in synaptic plasticity and vesicle function. Dysfunction of this protein might lead to increased cytoplasmic dopamine levels. Since cytoplasmic dopamine is readily prone to autooxidation and enzymatic degradation - processes which generate reactive oxygen species - failure to properly store dopamine into vesicles might lead to oxidative stress. Indeed, nigral tissue from idiopathic Parkinson’s disease patients shows signs of oxidative damage. In this article we propose that dopamine-induced oxidative stress might be a common final pathway in the pathogenesis of the disease.
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| 238605. |
- Smith, Ruben, et al.
(författare)
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Loss of SNAP-25 and rabphilin 3a in sensory-motor cortex in Huntington's disease.
- 2007
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Ingår i: Journal of Neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 103:1, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG-expansion in the gene encoding the protein huntingtin. The disease is characterized by progressive motor disturbances, cognitive defects, dementia, and weight loss. Using western blotting and immunohistochemistry we have assessed the expression levels and patterns of a number of proteins involved in neurotransmitter release in post-mortem frontal cortex samples from 10 HD cases with different disease grades. We report a loss of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein, synaptosome-associated protein 25 (SNAP 25) in HD brains of grades I–IV. Moreover, in brains of grade III and IV we found a reduction in rabphilin 3a, a protein involved in vesicle docking and recycling. These losses appear to be specific and not due to a general loss of synapses in the HD cortex. Thus, levels of synaptobrevin II, syntaxin 1, rab3a or synaptophysin are unaltered in the same patient samples. SNAP 25 and rabphilin 3a are crucial for neurotransmitter release. Therefore, we suggest that a deficient pre-synaptic transmitter release may underlie some of the symptoms of HD.
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| 238606. |
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| 238607. |
- Smith, Ruben, et al.
(författare)
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Tau-PET is superior to phospho-tau when predicting cognitive decline in symptomatic AD patients
- 2023
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:6, s. 2497-2507
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Biomarkers for the prediction of cognitive decline in patients with amnestic mild cognitive impairment (MCI) and amnestic mild dementia are needed for both clinical practice and clinical trials. Methods: We evaluated the ability of tau-PET (positron emission tomography), cortical atrophy on magnetic resonance imaging (MRI), baseline cognition, apolipoprotein E gene (APOE) status, plasma and cerebrospinal fluid (CSF) levels of phosphorylated tau-217, neurofilament light (NfL), and amyloid beta (Aβ)42/40 ratio (individually and in combination) to predict cognitive decline over 2 years in BioFINDER-2 and Alzheimer's Disease Neuroimaging Initiative (ADNI). Results: Baseline tau-PET and a composite baseline cognitive score were the strongest independent predictors of cognitive decline. Cortical thickness and NfL provided some additional information. Using a predictive algorithm to enrich patient selection in a theoretical clinical trial led to a significantly lower required sample size. Discussion: Models including baseline tau-PET and cognition consistently provided the best prediction of change in cognitive function over 2 years in patients with amnestic MCI or mild dementia.
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| 238608. |
- Smith, Ruben, et al.
(författare)
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The accumulation rate of tau aggregates is higher in females and younger amyloid-positive subjects
- 2020
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 143:12, s. 3805-3815
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Tidskriftsartikel (refereegranskat)abstract
- The development of tau-PET allows paired helical filament tau pathology to be visualized in vivo. Increased knowledge about conditions affecting the rate of tau accumulation could guide the development of therapies halting the progression of Alzheimer's disease. However, the factors modifying the rate of tau accumulation over time in Alzheimer's disease are still largely unknown. Large-scale longitudinal cohort studies, adjusting for baseline tau load, are needed to establish such risk factors. In the present longitudinal study, 419 participants from four cohorts in the USA (Avid 05e, n = 157; Expedition-3, n = 82; ADNI, n = 123) and Sweden (BioFINDER, n = 57) were scanned repeatedly with tau-PET. The study participants were cognitively unimpaired (n = 153), or patients with mild cognitive impairment (n = 139) or Alzheimer's disease dementia (n = 127). Participants underwent two to four tau-PET (18F-flortaucipir) scans with a mean (± standard deviation) of 537 (±163) days between the first and last scan. The change in tau-PET signal was estimated in temporal meta- and neocortical regions of interest. Subject specific tau-PET slopes were predicted simultaneously by age, sex, amyloid status (determined by amyloid-β PET), APOE ϵ4 genotype, study cohort, diagnosis and baseline tau load. We found that accelerated increase in tau-PET signal was observed in amyloid-β-positive mild cognitive impairment (3.0 ± 5.3%) and Alzheimer's disease dementia (2.9 ± 5.7%), respectively, when compared to either amyloid-β-negative cognitively unimpaired (0.4 ± 2.7%), amyloid-β-negative mild cognitive impairment (-0.4 ± 2.3%) or amyloid-β-positive cognitively unimpaired (1.2 ± 2.8%). Tau-PET uptake was accelerated in females (temporal region of interest: t = 2.86, P = 0.005; neocortical region of interest: t = 2.90, P = 0.004), younger individuals (temporal region of interest: t = -2.49, P = 0.013), and individuals with higher baseline tau-PET signal (temporal region of interest: t = 3.83, P < 0.001; neocortical region of interest: t = 5.01, P < 0.001). Tau-PET slopes decreased with age in amyloid-β-positive subjects, but were stable by age in amyloid-β-negative subjects (age × amyloid-β status interaction: t = -2.39, P = 0.018). There were no effects of study cohort or APOE ϵ4 positivity. In a similar analysis on longitudinal amyloid-β-PET (in ADNI subjects only, n = 639), we found significant associations between the rate of amyloid-β accumulation and APOE ϵ4 positivity, older age and baseline amyloid-β positivity, but no effect of sex. In conclusion, in this longitudinal PET study comprising four cohorts, we found that the tau accumulation rate is greater in females and younger amyloid-β-positive individuals, while amyloid-β accumulation is greater in APOE ϵ4 carriers and older individuals. These findings are important considerations for the design of clinical trials, and might improve our understanding of factors associated with faster tau aggregation and spread.
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| 238609. |
- Smith, Ruben, et al.
(författare)
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The role of pallidal serotonergic function in Parkinson's disease dyskinesias: a positron emission tomography study.
- 2015
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 36:4, s. 1736-1742
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the role of globus pallidus (GP) serotonergic terminals in the development of levodopa-induced dyskinesias (LIDs) in Parkinson's disease (PD). We studied 12 PD patients without LIDs, 12 PD patients with LIDs, and 12 healthy control subjects. We used (11)C-DASB positron emission tomography (PET), a marker of serotonin transporter availability, and (11)C-raclopride PET to measure changes in synaptic dopamine levels following levodopa administration. PD patients without LIDs showed a significant reduction of GP serotonin transporter binding compared with healthy controls although this was within the normal range in PD patients with LIDs. Levels of GP serotonin transporter binding correlated positively with severity of dyskinesias. (11)C-raclopride PET detected a significant rise in GP synaptic dopamine levels of patients with LIDs after a levodopa challenge but not in patients with a stable response. Our findings indicate that LIDs in PD are associated with higher GP serotonergic function. This increased serotonin function may result in further dysregulation of thalamocortical signals and so promote the expression of dyskinesias.
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| 238610. |
- Smith, Ruben, et al.
(författare)
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The α-synuclein PET tracer [18F] ACI-12589 distinguishes multiple system atrophy from other neurodegenerative diseases
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- A positron emission tomography (PET) tracer detecting α-synuclein pathology will improve the diagnosis, and ultimately the treatment of α-synuclein-related diseases. Here we show that the PET ligand, [18F]ACI-12589, displays good in vitro affinity and specificity for pathological α-synuclein in tissues from patients with different α-synuclein-related disorders including Parkinson’s disease (PD) and Multiple-System Atrophy (MSA) using autoradiography and radiobinding techniques. In the initial clinical evaluation we include 23 participants with α-synuclein related disorders, 11 with other neurodegenerative disorders and eight controls. In vivo [18F]ACI-12589 demonstrates clear binding in the cerebellar white matter and middle cerebellar peduncles of MSA patients, regions known to be highly affected by α-synuclein pathology, but shows limited binding in PD. The binding statistically separates MSA patients from healthy controls and subjects with other neurodegenerative disorders, including other synucleinopathies. Our results indicate that α-synuclein pathology in MSA can be identified using [18F]ACI-12589 PET imaging, potentially improving the diagnostic work-up of MSA and allowing for detection of drug target engagement in vivo of novel α-synuclein targeting therapies.
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