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Sökning: L773:1750 1326

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1.
  • Brinkmalm, Ann, et al. (författare)
  • SNAP-25 is a promising novel cerebrospinal fluid biomarker for synapse degeneration in Alzheimer's disease
  • 2014
  • Ingår i: Molecular Neurodegeneration. - : BioMed Central (BMC). - 1750-1326. ; 9
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Synaptic degeneration is an early pathogenic event in Alzheimer's disease, associated with cognitive impairment and disease progression. Cerebrospinal fluid biomarkers reflecting synaptic integrity would be highly valuable tools to monitor synaptic degeneration directly in patients. We previously showed that synaptic proteins such as synaptotagmin and synaptosomal-associated protein 25 (SNAP-25) could be detected in pooled samples of cerebrospinal fluid, however these assays were not sensitive enough for individual samples. Results: We report a new strategy to study synaptic pathology by using affinity purification and mass spectrometry to measure the levels of the presynaptic protein SNAP-25 in cerebrospinal fluid. By applying this novel affinity mass spectrometry strategy on three separate cohorts of patients, the value of SNAP-25 as a cerebrospinal fluid biomarker for synaptic integrity in Alzheimer's disease was assessed for the first time. We found significantly higher levels of cerebrospinal fluid SNAP-25 fragments in Alzheimer's disease, even in the very early stages, in three separate cohorts. Cerebrospinal fluid SNAP-25 differentiated Alzheimer's disease from controls with area under the curve of 0.901 (P < 0.0001). Conclusions: We developed a sensitive method to analyze SNAP-25 levels in individual CSF samples that to our knowledge was not possible previously. Our results support the notion that synaptic biomarkers may be important tools for early diagnosis, assessment of disease progression, and to monitor drug effects in treatment trials.
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2.
  • Portelius, Erik, 1977, et al. (författare)
  • Distinct cerebrospinal fluid amyloid beta peptide signatures in sporadic and PSEN1 A431E-associated familial Alzheimer's disease.
  • 2010
  • Ingår i: Molecular neurodegeneration. - : BioMed Central (BMC). - 1750-1326. ; 5:2
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Alzheimer's disease (AD) is associated with deposition of amyloid beta (Abeta) in the brain, which is reflected by low concentration of the Abeta1-42 peptide in the cerebrospinal fluid (CSF). There are at least 15 additional Abeta peptides in human CSF and their relative abundance pattern is thought to reflect the production and degradation of Abeta. Here, we test the hypothesis that AD is characterized by a specific CSF Abeta isoform pattern that is distinct when comparing sporadic AD (SAD) and familial AD (FAD) due to different mechanisms underlying brain amyloid pathology in the two disease groups. RESULTS: We measured Abeta isoform concentrations in CSF from 18 patients with SAD, 7 carriers of the FAD-associated presenilin 1 (PSEN1) A431E mutation, 17 healthy controls and 6 patients with depression using immunoprecipitation-mass spectrometry. Low CSF levels of Abeta1-42 and high levels of Abeta1-16 distinguished SAD patients and FAD mutation carriers from healthy controls and depressed patients. SAD and FAD were characterized by similar changes in Abeta1-42 and Abeta1-16, but FAD mutation carriers exhibited very low levels of Abeta1-37, Abeta1-38 and Abeta1-39. CONCLUSION: SAD patients and PSEN1 A431E mutation carriers are characterized by aberrant CSF Abeta isoform patterns that hold clinically relevant diagnostic information. PSEN1 A431E mutation carriers exhibit low levels of Abeta1-37, Abeta1-38 and Abeta1-39; fragments that are normally produced by gamma-secretase, suggesting that the PSEN1 A431E mutation modulates gamma-secretase cleavage site preference in a disease-promoting manner.
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3.
  • Rosén, Christoffer, 1986, et al. (författare)
  • Fluid biomarkers in Alzheimer's disease - current concepts
  • 2013
  • Ingår i: Molecular Neurodegeneration. - : BioMed Central (BMC). - 1750-1326. ; 8:20
  • Tidskriftsartikel (refereegranskat)abstract
    • The diagnostic guidelines of Alzheimer's disease (AD) have recently been updated to include brain imaging and cerebrospinal fluid (CSF) biomarkers, with the aim of increasing the certainty of whether a patient has an ongoing AD neuropathologic process or not. The CSF biomarkers total tau (T-tau), hyperphosphorylated tau (P-tau) and the 42 amino acid isoform of amyloid beta (A beta 42) reflect the core pathologic features of AD, which are neuronal loss, intracellular neurofibrillary tangles and extracellular senile plaques. Since the pathologic processes of AD start decades before the first symptoms, these biomarkers may provide means of early disease detection. The updated guidelines identify three different stages of AD: preclinical AD, mild cognitive impairment (MCI) due to AD and AD with dementia. In this review, we aim to summarize the CSF biomarker data available for each of these stages. We also review results from blood biomarker studies. In summary, the core AD CSF biomarkers have high diagnostic accuracy both for AD with dementia and to predict incipient AD (MCI due to AD). Longitudinal studies on healthy elderly and recent cross-sectional studies on patients with dominantly inherited AD mutations have also found biomarker changes in cognitively normal at-risk individuals. This will be important if disease-modifying treatment becomes available, given that treatment will probably be most effective early in the disease. An important prerequisite for this is trustworthy analyses. Since measurements vary between studies and laboratories, standardization of analytical as well as pre-analytical procedures will be essential. This process is already initiated. Apart from filling diagnostic roles, biomarkers may also be utilized for prognosis, disease progression, development of new treatments, monitoring treatment effects and for increasing the knowledge about pathologic processes coupled to the disease. Hence, the search for new biomarkers continues. Several candidate biomarkers have been found in CSF, and although biomarkers in blood have been harder to find, some recent studies have presented encouraging results. But before drawing any major conclusions, these results need to be verified in independent studies.
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4.
  • Sjolander, Annica, et al. (författare)
  • BACE1 gene variants do not influence BACE1 activity, levels of APP or A beta isoforms in CSF in Alzheimer's disease
  • 2010
  • Ingår i: Molecular Neurodegeneration. - : BioMed Central (BMC). - 1750-1326. ; 5
  • Tidskriftsartikel (refereegranskat)abstract
    • The BACE1 gene encodes the beta-site APP-cleaving enzyme 1 and has been associated with Alzheimer's disease (AD). BACE1 is the most important beta-secretase responsible for the generation of Alzheimer-associated amyloid beta-proteins (A beta) and may play a role in the amyloidogenic process in AD. We hypothesized that BACE1 gene variants might influence BACE1 activity or other markers for APP metabolism in the cerebrospinal fluid (CSF) and thereby contribute to the development of AD. We genotyped a Swedish sample of 269 AD patients for the rs638405 single nucleotide polymorphism (SNP) in the BACE1 gene and correlated genotype data to a broad range of amyloid-related biomarkers in CSF, including BACE1 activity, levels of Ab40, A beta(42), alpha- and beta-cleaved soluble APP (alpha-sAPP and beta-sAPP), as well as markers for Alzheimer-type axonal degeneration, i.e., total-tau and phospho-tau181. Gene variants of BACE1 were neither associated with amyloid-related biomarkers, nor with markers for axonal degeneration in AD.
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5.
  • Zetterberg, Madeleine, 1969, et al. (författare)
  • Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) S18Y polymorphism in Alzheimer's disease.
  • 2010
  • Ingår i: Molecular neurodegeneration. - : BioMed Central (BMC). - 1750-1326. ; 5
  • Tidskriftsartikel (refereegranskat)abstract
    • ABSTRACT: Alzheimer's disease (AD) is characterized by protein aggregates, i.e. senile plaques and neurofibrillary tangles. The ubiquitin-proteasome system has been proposed a role in proteolytic removal of these protein aggregates. Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) is a de-ubiquitinating enzyme with important functions in recycling of ubiquitin. The S18Y polymorphism of the UCHL1 gene confers protection against Parkinson's disease. In this study, the genotype and allele frequencies of the UCHL1 S18Y polymorphism were investigated in 452 AD patients and 234 control subjects, recruited from four memory clinics in Sweden. Using a binary logistic regression model including UCHL1 allele A and APOE epsilon4 allele positivity, age and sex as covariates with AD diagnosis as dependent variable, an adjusted OR of 0.82 ([95% CI 0.55-1.24], P = 0.35) was obtained for a positive UCHL1 allele A carrier status. The present study thus do not support a protective effect of the UCHL1 S18Y polymorphism against AD.
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6.
  • Casadesus, Gemma, et al. (författare)
  • Increased isoprostane and prostaglandin are prominent in neurons in Alzheimer disease
  • 2007
  • Ingår i: Molecular Neurodegeneration. - 1750-1326. ; 2:1, s. 2-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Inflammation and oxidative stress are both involved in the pathogenesis of Alzheimer disease and have been shown to be reciprocally linked. One group of molecules that have been directly associated with inflammation and the production of free radicals are the prostaglandin 13,14-dihydro 15-keto PGF2α and the isoprostane 8-iso-PGF2α. Results To further delineate the role of inflammatory and oxidative parameters in Alzheimer disease, in this study we evaluated the amount and localization of 13,14-dihydro 15-keto PGF2α and 8-iso-PGF2α in hippocampal post mortem tissue samples from age-matched Alzheimer disease and control patients. Our results demonstrate increased levels of 13,14-dihydro 15-keto PGF2α and 8-iso-PGF2α in the hippocampal pyramidal neurons of Alzheimer disease patients when compared to control patients. Conclusion These data not only support the shared mechanistic involvement of free radical damage and inflammation in Alzheimer disease, but also indicate that multiple pathogenic "hits" are likely necessary for both the development and propagation of Alzheimer disease.
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7.
  • Cuchillo-Ibañez, Inmaculada, et al. (författare)
  • Heteromers of amyloid precursor protein in cerebrospinal fluid.
  • 2015
  • Ingår i: Molecular neurodegeneration. - 1750-1326. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Soluble fragments of the amyloid precursor protein (APP) generated by α- and β-secretases, sAPPα and sAPPβ, have been postulated as promising new cerebrospinal fluid (CSF) biomarkers for the clinical diagnosis of Alzheimer's disease (AD). However, the capacity of these soluble proteins to assemble has not been explored and could be relevant. Our aim is to characterize possible sAPP oligomers that could contribute to the quantification of sAPPα and sAPPβ in CSF by ELISA, as well as to characterize the possible presence of soluble full-length APP (sAPPf).
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8.
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9.
  • Figueroa, Ricardo A. (författare)
  • Anchored FRET sensors detect local caspase activation prior to neuronal degeneration
  • 2011
  • Ingår i: ; 6, s. 35-
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Recent studies indicate local caspase activation in dendrites or axons during development and in neurodegenerative disorders such as Alzheimer's disease (AD). Emerging evidences point to soluble oligomeric amyloid-beta peptide as a causative agent in AD.RESULTS: Here we describe the design of fluorescence resonance energy transfer (FRET)-based caspase sensors, fused to the microtubule associated protein tau. Specific caspase sensors preferentially cleaved by caspase-3, -6 or -9 were expressed in differentiated human neuroblastoma SH-SY5Y cells. The anchoring of the sensors resulted in high FRET signals both in extended neurites and soma and made analysis of spatiotemporal signal propagation possible. Caspase activation was detected as loss of FRET after exposure to different stimuli. Interestingly, after staurosporine treatment caspase-6 activation was significantly delayed in neurites compared to cell bodies. In addition, we show that exposure to oligomer-enriched amyloid-beta peptide resulted in loss of FRET in cells expressing sensors for caspase-3 and -6, but not -9, in both soma and neurites before neurite degeneration was observed.CONCLUSIONS: Taken together, the results show that by using anchored FRET sensors it is possible to detect stimuli-dependent differential activation of caspases and to distinguish local from global caspase activation in live neuronal cells. Furthermore, in these cells oligomer-enriched amyloid-beta peptide induces a global, rather than local activation of caspase-3 and -6, which subsequently leads to neuronal cell death.
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10.
  • Guzman, Erika Avendano, et al. (författare)
  • Abundance of A beta(5-x) x like immunoreactivity in transgenic 5XFAD, APP/PS1KI and 3xTG mice, sporadic and familial Alzheimer's disease
  • 2014
  • Ingår i: Molecular Neurodegeneration. - 1750-1326 .- 1750-1326. ; 9, s. 13-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: According to the modified amyloid hypothesis the main event in the pathogenesis of Alzheimer's disease (AD) is the deposition of neurotoxic amyloid beta-peptide (A beta) within neurons. Additionally to full-length peptides, a great diversity of N-truncated A beta variants is derived from the larger amyloid precursor protein (APP). Vast evidence suggests that A beta(x-42) isoforms play an important role triggering neurodegeneration due to its high abundance, amyloidogenic propensity and toxicity. Although N-truncated and A beta(x-42) species have been pointed as crucial players in AD etiology, the A beta(5-x) isoforms have not received much attention. Results: The present study is the first to show immunohistochemical evidence of A beta(5-x) in familial cases of AD (FAD) and its distribution in APP/PS1KI, 5XFAD and 3xTG transgenic mouse models. In order to probe A beta(5-x) peptides we generated the AB5-3 antibody. Positive plaques and congophilic amyloid angiopathy (CAA) were observed among all the FAD cases tested carrying either APP or presenilin 1 (PS1) mutations and most of the sporadic cases of AD (SAD). Different patterns of A beta(5-x) distribution were found in the mouse models carrying different combinations of autosomal mutations in the APP, PS1 and Tau genes. All of them showed extracellular A beta deposits but none CAA. Additionally, they were all affected by a severe amyloid pathology in the hippocampus among other areas. Interestingly, neither 5XFAD nor APP/PS1KI showed any evidence for intraneuronal A beta(5-x). Conclusions: Different degrees of A beta(5-x) accumulations can be found in the transgenic AD mouse models and human cases expressing the sporadic or the familial form of the disease. Due to the lack of intracellular A beta(5-x), these isoforms might not be contributing to early mechanisms in the cascade of events triggering AD pathology. Brain sections obtained from SAD cases showed higher A beta(5-x)-immunoreactivity in vascular deposits than in extracellular plaques, while both are equally important in the FAD cases. The difference may rely on alternative mechanisms involving A beta(5-x) peptides and operating in a divergent way in the late and early onset forms of the disease.
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