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- Aad, G, et al.
(författare)
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- 2015
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swepub:Mat__t
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- Chatterjee, P., et al.
(författare)
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Plasma metabolites associated with biomarker evidence of neurodegeneration in cognitively normal older adults
- 2021
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 159:2, s. 389-402
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is a progressive neurodegenerative disorder that currently has no cure. Identifying biochemical changes associated with neurodegeneration prior to symptom onset, will provide insight into the biological mechanisms associated with neurodegenerative processes, that may also aid in identifying potential drug targets. The current study therefore investigated associations between plasma neurofilament light chain (NF-L), a marker of neurodegeneration, with plasma metabolites that are products of various cellular processes. Plasma NF-L, measured by ultrasensitive Single molecule array (Simoa) technology (Quanterix) and plasma metabolites, measured by mass-spectrometry (AbsoluteIDQ (R) p400HR kit, BIOCRATES), were assessed in the Kerr Anglican Retirement Village Initiative in Ageing Health (KARVIAH) cohort comprising 100 cognitively normal older adults. Metabolites belonging to biogenic amine (creatinine, symmetric dimethylarginine, asymmetric dimethylarginine; ADMA, kynurenine, trans-4-hydroxyproline), amino acid (citrulline, proline, arginine, asparagine, phenylalanine, threonine) and acylcarnitine classes were observed to have positive correlations with plasma NF-L, suggesting a link between neurodegeneration and biological pathways associated with neurotransmitter regulation, nitric oxide homoeostasis, inflammation and mitochondrial function. Additionally, after stratifying participants based on low/high brain amyloid-beta load (A beta +/-) assessed by positron emission tomography, while creatinine, SDMA and citrulline correlated with NF-L in both A beta- and A beta+ groups, ADMA, proline, arginine, asparagine, phenylalanine and acylcarnitine species correlated with NF-L only in the A beta+ group after adjusting for confounding variables, suggesting that the association of these metabolites with neurodegeneration may be relevant to AD-related neuropathology. Metabolites identified to be associated with plasma NF-L may have the potential to serve as prognostic markers for neurodegenerative diseases, however, further studies are required to validate the current findings in an independent cohort, both cross-sectionally and longitudinally.
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- Chatterjee, Pratishtha, et al.
(författare)
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Plasma glial fibrillary acidic protein is elevated in cognitively normal older adults at risk of Alzheimer's disease.
- 2021
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Ingår i: Translational psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Glial fibrillary acidic protein (GFAP), an astrocytic cytoskeletal protein, can be measured in blood samples, and has been associated with Alzheimer's disease (AD). However, plasma GFAP has not been investigated in cognitively normal older adults at risk of AD, based on brain amyloid-β (Aβ) load. Cross-sectional analyses were carried out for plasma GFAP and plasma Aβ1-42/Aβ1-40 ratio, a blood-based marker associated with brain Aβ load, in participants (65-90 years) categorised into low (Aβ-, n=63) and high (Aβ+, n=33) brain Aβ load groups via Aβ positron emission tomography. Plasma GFAP, Aβ1-42, and Aβ1-40 were measured using the Single molecule array (Simoa) platform. Plasma GFAP levels were significantly higher (p<0.00001), and plasma Aβ1-42/Aβ1-40 ratios were significantly lower (p<0.005), in Aβ+ participants compared to Aβ- participants, adjusted for covariates age, sex, and apolipoprotein E-ε4 carriage. A receiver operating characteristic curve based on a logistic regression of the same covariates, the base model, distinguished Aβ+ from Aβ- (area under the curve, AUC=0.78), but was outperformed when plasma GFAP was added to the base model (AUC=0.91) and further improved with plasma Aβ1-42/Aβ1-40 ratio (AUC=0.92). The current findings demonstrate that plasma GFAP levels are elevated in cognitively normal older adults at risk of AD. These observations suggest that astrocytic damage or activation begins from the pre-symptomatic stage of AD and is associated with brain Aβ load. Observations from the present study highlight the potential of plasma GFAP to contribute to a diagnostic blood biomarker panel (along with plasma Aβ1-42/Aβ1-40 ratios) for cognitively normal older adults at risk of AD.
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- Chatterjee, P., et al.
(författare)
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Serum Hepcidin Levels in Cognitively Normal Older Adults with High Neocortical Amyloid-beta Load
- 2020
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 76:1, s. 291-301
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Tidskriftsartikel (refereegranskat)abstract
- Background/Objective: Hepcidin, an iron-regulating hormone, suppresses the release of iron by binding to the iron exporter protein, ferroportin, resulting in intracellular iron accumulation. Given that iron dyshomeostasis has been observed in Alzheimer's disease (AD) together with elevated serum hepcidin levels, the current study examined whether elevated serum hepcidin levels are an early event in AD pathogenesis by measuring the hormone in cognitively normal older adults at risk of AD, based on high neocortical amyloid-beta load (NAL). Methods: Serum hepcidin levels in cognitively normal participants (n = 100) aged between 65-90 years were measured using ELISA. To evaluate NAL, all participants underwent 18F-florbetaben positron emission tomography. A standard uptake value ratio (SUVR)<1.35 was classified as low NAL (n = 65) and >= 1.35 (n = 35) was classified as high NAL. Results: Serum hepcidin was significantly higher in participants with high NAL compared to those with low NAL before and after adjusting for covariates: age, gender, and APOE epsilon 4 carriage (p < 0.05). A receiver operating characteristic curve based on a logistic regression of the same covariates, the base model, distinguished high from low NAL (area under the curve, AUC = 0.766), but was outperformed when serum hepcidin was added to the base model (AUC = 0.794) and further improved with plasma A beta(42/40) ratio (AUC = 0.829). Conclusion: The present findings indicate that serum hepcidin is increased in individuals at risk for AD and contribute to the body of evidence supporting iron dyshomeostasis as an early event of AD. Further, hepcidin may add value to a panel of markers that contribute toward identifying individuals at risk of AD; however, further validation studies are required.
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- Frank, Matthias, et al.
(författare)
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Femtosecond X-ray diffraction from two-dimensional protein crystals
- 2014
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Ingår i: IUCrJ. - 2052-2525. ; 1:2, s. 95-100
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Tidskriftsartikel (refereegranskat)abstract
- X-ray diffraction patterns from two-dimensional (2-D) protein crystals obtained using femtosecond X-ray pulses from an X-ray free-electron laser (XFEL) are presented. To date, it has not been possible to acquire transmission X-ray diffraction patterns from individual 2-D protein crystals due to radiation damage. However, the intense and ultrafast pulses generated by an XFEL permit a new method of collecting diffraction data before the sample is destroyed. Utilizing a diffract-before-destroy approach at the Linac Coherent Light Source, Bragg diffraction was acquired to better than 8.5 Å resolution for two different 2-D protein crystal samples each less than 10 nm thick and maintained at room temperature. These proof-of-principle results show promise for structural analysis of both soluble and membrane proteins arranged as 2-D crystals without requiring cryogenic conditions or the formation of three-dimensional crystals.
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- Sheikh, U., et al.
(författare)
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Benign termination of runaway electron beams on ASDEX Upgrade and TCV
- 2024
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 66:3
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses the development of a benign termination scenario for runaway electron (RE) beams on ASDEX Upgrade and TCV. A systematic study revealed that a low electron density (n e) companion plasma was required to achieve a large MHD instability, which expelled the confined REs over a large wetted area and allowed for the conversion of magnetic energy to radiation. Control of the companion plasma ne was achieved via neutral pressure regulation and was agnostic to material injection method. The neutral pressure required for recombination was found to be dependent on impurity species, quantity and RE current. On TCV, n e increased at neutral pressures above 1 Pa, indicating that higher collisionality between the REs and neutrals may lead to an upper pressure limit. The conversion of magnetic energy to radiated energy was measured on both machines and a decrease in efficiency was observed at high neutral pressure on TCV. The benign termination technique was able to prevent any significant increase in maximum heat flux on AUG from 200 to 600 kA of RE current, highlighting the ability of this approach to handle fully formed RE beams.
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- Yuan, J., et al.
(författare)
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Elevated plasma sclerostin is associated with high brain amyloid-β load in cognitively normal older adults
- 2023
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Ingår i: Npj Aging. - 2731-6068. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Osteoporosis and Alzheimer's disease (AD) mainly affect older individuals, and the possibility of an underlying link contributing to their shared epidemiological features has rarely been investigated. In the current study, we investigated the association between levels of plasma sclerostin (SOST), a protein primarily produced by bone, and brain amyloid-beta (A ss) load, a pathological hallmark of AD. The study enrolled participants meeting a set of screening inclusion and exclusion criteria and were stratified into A ss(n = 65) and A ss+ (n = 35) according to their brain A ss load assessed using A ss-PET (positron emission tomography) imaging. Plasma SOST levels, apolipoprotein E gene (APOE) genotype and several putative AD blood-biomarkers including A ss 40, A ss 42, A ss 42/A ss 40, neurofilament light (NFL), glial fibrillary acidic protein (GFAP), total tau (t-tau) and phosphorylated tau (p-tau181 and p-tau231) were detected and compared. It was found that plasma SOST levels were significantly higher in the A ss+ group (71.49 +/- 25.00 pmol/L) compared with the A ss- group (56.51 +/- 22.14 pmol/L) (P < 0.01). Moreover, Spearman's correlation analysis showed that plasma SOST concentrations were positively correlated with brain A ss load (. = 0.321, P = 0.001). Importantly, plasma SOST combined with A ss 42/A ss 40 ratio significantly increased the area under the curve (AUC) when compared with using A ss 42/A ss 40 ratio alone (AUC = 0.768 vs 0.669, P = 0.027). In conclusion, plasma SOST levels are elevated in cognitively unimpaired older adults at high risk of AD and SOST could complement existing plasma biomarkers to assist in the detection of preclinical AD.
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- Chatterjee, P., et al.
(författare)
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Ultrasensitive Detection of Plasma Amyloid-beta as a Biomarker for Cognitively Normal Elderly Individuals at Risk of Alzheimer's Disease
- 2019
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Ingår i: Journal of Alzheimers Disease. - 1387-2877. ; 71:3, s. 775-783
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Tidskriftsartikel (refereegranskat)abstract
- Background: Aberrant amyloid-beta (A beta) deposition in the brain occurs two decades prior to the manifestation of Alzheimer's disease (AD) clinical symptoms and therefore brain A beta load measured using PET serves as a gold standard biomarker for the early diagnosis of AD. However, the uneconomical nature of PET makes blood markers, that reflect brain A beta deposition, attractive candidates for investigation as surrogate markers. Objective: Investigation of plasma A beta as a surrogate marker for brain A beta deposition in cognitively normal elderly individuals. Methods: Plasma A beta(40) and A beta(42) concentrations were measured using the ultrasensitive Single Molecule Array (Simoa) assay in 95 cognitively normal elderly individuals, who have all undergone PET to assess brain A beta deposition. Based on the standard uptake value ratios (SUVR) obtained from PET imaging, using the tracer F-18-Florbetaben, plasma A beta was compared between 32 participants assessed to have low brain A beta load (A beta-, SUVR <1.35) and 63 assessed to have high brain A beta load (A beta+, SUVR >= 1.35). Results: Plasma A beta(42)/A beta(40) ratios were lower in the A beta+ group compared to the A beta- group. Plasma A beta(40) and A beta(42) levels were not significantly different between A beta- and A beta+ groups, although a trend of higher plasma A beta(40) was observed in the A beta+ group. Additionally, plasma A beta(42)/A beta(40) ratios along with the known AD risk factors, age and APOE epsilon 4 status, resulted in A beta+ participants being distinguished from A beta- participants based on an area under the receiver operating characteristic curve shown to be 78%. Conclusion: Plasma A beta ratios in this study are a potential biomarker for brain A beta deposition and therefore, for preclinical AD. However, this method to measure plasma A beta needs further development to increase the accuracy of this promising AD blood biomarker.
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- Pettersen, Emily, 1996, et al.
(författare)
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Targeted Muscle Reinnervation: Surgical Protocol for a Randomized Controlled Trial in Postamputation Pain
- 2024
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Ingår i: Journal of Visualized Experiments. - 1940-087X. ; 2024:205
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decade, the field of prosthetics has witnessed significant progress, particularly in the development of surgical techniques to enhance the functionality of prosthetic limbs. Notably, novel surgical interventions have had an additional positive outcome, as individuals with amputations have reported neuropathic pain relief after undergoing such procedures. Subsequently, surgical techniques have gained increased prominence in the treatment of postamputation pain, including one such surgical advancement-targeted muscle reinnervation (TMR). TMR involves a surgical approach that reroutes severed nerves as a type of nerve transfer to "target" motor nerves and their accompanying motor end plates within nearby muscles. This technique originally aimed to create new myoelectric sites for amplified electromyography (EMG) signals to enhance prosthetic intuitive control. Subsequent work showed that TMR also could prevent the formation of painful neuromas as well as reduce postamputation neuropathic pain (e.g., Residual and Phantom Limb Pain). Indeed, multiple studies have demonstrated TMR's effectiveness in mitigating postamputation pain as well as improving prosthetic functional outcomes. However, technical variations in the procedure have been identified as it is adopted by clinics worldwide. The purpose of this article is to provide a detailed step-by-step description of the TMR procedure, serving as the foundation for an international, randomized controlled trial (ClinicalTrials.gov, NCT05009394), including nine clinics in seven countries. In this trial, TMR and two other surgical techniques for managing postamputation pain will be evaluated.
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- Villanueva-Perez, P., et al.
(författare)
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Hard x-ray multi-projection imaging for single-shot approaches
- 2018
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Ingår i: Optica. - 2334-2536. ; 5:12, s. 1521-1524
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Tidskriftsartikel (refereegranskat)abstract
- High-brilliance x-ray sources (x-ray free-electron lasers or diffraction-limited storage rings) allow the visualization of ultrafast processes in a 2D manner using single exposures. Current 3D approaches scan the sample using multiple exposures, and hence they are not compatible with single-shot acquisitions. Here we propose and verify experimentally an x-ray multi-projection imaging approach, which uses a crystal to simultaneously acquire nine angularly resolved projections with a single x-ray exposure. When implemented at high-brilliance sources, this approach can provide volumetric information of natural processes and non-reproducible samples in the micrometer to nanometer resolution range, and resolve timescales from microseconds down to femto-seconds.
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