| 1. |
- Barthélemy, Nicolas R., et al.
(författare)
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CSF tau phosphorylation occupancies at T217 and T205 represent improved biomarkers of amyloid and tau pathology in Alzheimer’s disease
- 2023
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Ingår i: Nature Aging. - : Springer Science and Business Media LLC. - 2662-8465. ; 3:4, s. 391-401
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Tidskriftsartikel (refereegranskat)abstract
- Cerebrospinal fluid (CSF) amyloid-β peptide (Aβ)42/Aβ40 and the concentration of tau phosphorylated at site 181 (p-tau181) are well-established biomarkers of Alzheimer’s disease (AD). The present study used mass spectrometry to measure concentrations of nine phosphorylated and five nonphosphorylated tau species and phosphorylation occupancies (percentage phosphorylated/nonphosphorylated) at ten sites. In the present study we show that, in 750 individuals with a median age of 71.2 years, CSF pT217/T217 predicted the presence of brain amyloid by positron emission tomography (PET) slightly better than Aβ42/Aβ40 (P = 0.02). Furthermore, for individuals with positive brain amyloid by PET (n = 263), CSF pT217/T217 was more strongly correlated with the amount of amyloid (Spearman’s ρ = 0.69) than Aβ42/Aβ40 (ρ = −0.42, P < 0.0001). In two independent cohorts of participants with symptoms of AD dementia (n = 55 and n = 90), CSF pT217/T217 and pT205/T205 were better correlated with tau PET measures than CSF p-tau181 concentration. These findings suggest that CSF pT217/T217 and pT205/T205 represent improved CSF biomarkers of amyloid and tau pathology in AD.
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| 2. |
- Chang, Yue, et al.
(författare)
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Cd-Metallothioneins in Three Additional Tetrahymena Species : Intragenic Repeat Patterns and Induction by Metal Ions
- 2014
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Ingår i: Journal of Eukaryotic Microbiology. - : Wiley. - 1066-5234 .- 1550-7408. ; 61:4, s. 333-342
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Tidskriftsartikel (refereegranskat)abstract
- Ciliate metallothioneins (MTs) possess many unique features compared to the "classic" MTs in other organisms, but they have only been studied in a small number of species. In this study, we investigated cDNAs encoding subfamily 7a metallothioneins (CdMTs) in three Tetrahymena species (T. hegewischi, T. malaccensis, and T. mobilis). Four CdMT genes (ThegMT1, ThegMT2, TmalMT1, and TmobMT1) were cloned and characterized. They share high sequence similarity to previously identified subfamily 7a MT members. Tetrahymena CdMTs exhibit a remarkably regular intragenic repeat homology. The CdMT sequences were divided into two main types of modules, which had been previously described, and which we name "A" and "B". ThegMT2 was identified as the first MT isoform solely composed of module "B". A phylogenetic analysis of individual modules of every characterized Tetrahymena CdMT rigorously documents the conclusion that modules are important units of CdMT evolution, which have undergone frequent and rapid gain/loss and shuffling. The transcriptional activity of the four newly identified genes was measured under different heavy metal exposure (Cd, Cu, Zn, Pb) using real-time quantitative PCR. The results showed that these genes were differentially induced after short (1 h) or long (24 h) metal exposure. The evolutionary diversity of Tetrahymena CdMTs is further discussed with regard to their induction by metal ions.
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| 3. |
- Levin, Johannes, et al.
(författare)
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α-Synuclein seed amplification assay detects Lewy body co-pathology in autosomal dominant Alzheimer's disease late in the disease course and dependent on Lewy pathology burden
- 2024
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Ingår i: Alzheimer's and Dementia. - 1552-5260.
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Amyloid beta and tau pathology are the hallmarks of sporadic Alzheimer's disease (AD) and autosomal dominant AD (ADAD). However, Lewy body pathology (LBP) is found in ≈ 50% of AD and ADAD brains. METHODS: Using an α-synuclein seed amplification assay (SAA) in cerebrospinal fluid (CSF) from asymptomatic (n = 26) and symptomatic (n = 27) ADAD mutation carriers, including 12 with known neuropathology, we investigated the timing of occurrence and prevalence of SAA positive reactivity in ADAD in vivo. RESULTS: No asymptomatic participant and only 11% (3/27) of the symptomatic patients tested SAA positive. Neuropathology revealed LBP in 10/12 cases, primarily affecting the amygdala or the olfactory areas. In the latter group, only the individual with diffuse LBP reaching the neocortex showed α-synuclein seeding activity in CSF in vivo. DISCUSSION: Results suggest that in ADAD LBP occurs later than AD pathology and often as amygdala- or olfactory-predominant LBP, for which CSF α-synuclein SAA has low sensitivity. Highlights: Cerebrospinal fluid (CSF) real-time quaking-induced conversion (RT-QuIC) detects misfolded α-synuclein in ≈ 10% of symptomatic autosomal dominant Alzheimer's disease (ADAD) patients. CSF RT-QuIC does not detect α-synuclein seeding activity in asymptomatic mutation carriers. Lewy body pathology (LBP) in ADAD mainly occurs as olfactory only or amygdala-predominant variants. LBP develops late in the disease course in ADAD. CSF α-synuclein RT-QuIC has low sensitivity for focal, low-burden LBP.
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| 4. |
- Schindler, Suzanne E, et al.
(författare)
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Effect of Race on Prediction of Brain Amyloidosis by Plasma Aβ42/Aβ40, Phosphorylated Tau, and Neurofilament Light.
- 2022
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Ingår i: Neurology. - 1526-632X. ; 99:3
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate whether plasma biomarkers of amyloid (Aβ42/Aβ40), tau (p-tau181 and p-tau231) and neuroaxonal injury (neurofilament light chain [NfL]) detect brain amyloidosis consistently across racial groups.Individuals enrolled in studies of memory and aging who self-identified as African American (AA) were matched 1:1 to self-identified non-Hispanic White (NHW) individuals by age, APOE ε4 carrier status and cognitive status. Each participant underwent blood and cerebrospinal fluid (CSF) collection, and amyloid PET was performed in 103 participants (68%). Plasma Aβ42/Aβ40 was measured by a high-performance immunoprecipitation-mass spectrometry assay. Plasma p-tau181, p-tau231, and NfL were measured by Simoa immunoassays. CSF Aβ42/Aβ40 and amyloid PET status were used as primary and secondary reference standards of brain amyloidosis, respectively.There were 76 matched pairs of AA and NHW participants (n=152 total). For both AA and NHW groups, the median age was 68.4 years, 42% were APOE ε4 carriers and 91% were cognitively normal. AA were less likely than NHW to have brain amyloidosis by CSF Aβ42/Aβ40 (22% versus 43% positive, p = 0.003). The Receiver Operating Characteristic Area Under the Curve (ROC AUC) of CSF Aβ42/Aβ40 status with the plasma biomarkers was as follows: Aβ42/Aβ40, 0.86 (95% confidence intervals [CI] 0.79-0.92); p-tau181, 0.76 (0.68-0.84); p-tau231, 0.69 (0.60-0.78); and NfL, 0.64 (0.55-0.73). In models predicting CSF Aβ42/Aβ40 status with plasma Aβ42/Aβ40 that included covariates (age, sex, APOE ε4 carrier status, race, and cognitive status), race did not affect the probability of CSF Aβ42/Aβ40 positivity. In similar models based on plasma p-tau181, p-tau231 or Nfl, AA had a lower probability of CSF Aβ42/Aβ40 positivity (Odds Ratio [OR] 0.31 [95% CI 0.13-0.73], OR 0.30 [0.13-0.71]) and OR 0.27 [0.12-0.64], respectively. Models of amyloid PET status yielded similar findings.Models predicting brain amyloidosis using a high performance plasma Aβ42/Aβ40 assay may provide an accurate and consistent measure of brain amyloidosis across AA and NHW groups, but models based on plasma p-tau181, p-tau231, and NfL may perform inconsistently and could result in disproportionate misdiagnosis of AA.
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| 5. |
- Xiong, Jie, et al.
(författare)
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Genome-wide identification and evolution of ATP-binding cassette transporters in the ciliate Tetrahymena thermophila : A case of functional divergence in a multigene family
- 2010
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 10:1, s. 330-
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Tidskriftsartikel (refereegranskat)abstract
- Background. In eukaryotes, ABC transporters that utilize the energy of ATP hydrolysis to expel cellular substrates into the environment are responsible for most of the efflux from cells. Many members of the superfamily of ABC transporters have been linked with resistance to multiple drugs or toxins. Owing to their medical and toxicological importance, members of the ABC superfamily have been studied in several model organisms and warrant examination in newly sequenced genomes. Results. A total of 165 ABC transporter genes, constituting a highly expanded superfamily relative to its size in other eukaryotes, were identified in the macronuclear genome of the ciliate Tetrahymena thermophila. Based on ortholog comparisons, phylogenetic topologies and intron characterizations, each highly expanded ABC transporter family of T. thermophila was classified into several distinct groups, and hypotheses about their evolutionary relationships are presented. A comprehensive microarray analysis revealed divergent expression patterns among the members of the ABC transporter superfamily during different states of physiology and development. Many of the relatively recently formed duplicate pairs within individual ABC transporter families exhibit significantly different expression patterns. Further analysis showed that multiple mechanisms have led to functional divergence that is responsible for the preservation of duplicated genes. Conclusion. Gene duplications have resulted in an extensive expansion of the superfamily of ABC transporters in the Tetrahymena genome, making it the largest example of its kind reported in any organism to date. Multiple independent duplications and subsequent divergence contributed to the formation of different families of ABC transporter genes. Many of the members within a gene family exhibit different expression patterns. The combination of gene duplication followed by both sequence divergence and acquisition of new patterns of expression likely plays a role in the adaptation of Tetrahymen a to its environment.
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