Academic literature on the topic 'Soluble tau protein'
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Journal articles on the topic "Soluble tau protein"
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Webster, Jack M., April L. Darling, Taylor A. Sanders, Danielle M. Blazier, Yamile Vidal-Aguiar, David Beaulieu-Abdelahad, Drew G. Plemmons, et al. "Hsp22 with an N-Terminal Domain Truncation Mediates a Reduction in Tau Protein Levels." International Journal of Molecular Sciences 21, no. 15 (July 30, 2020): 5442. http://dx.doi.org/10.3390/ijms21155442.
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Misfolding, aggregation and accumulation of proteins are toxic elements in the progression of a broad range of neurodegenerative diseases. Molecular chaperones enable a cellular defense by reducing or compartmentalizing these insults. Small heat shock proteins (sHsps) engage proteins early in the process of misfolding and can facilitate their proper folding or refolding, sequestration, or clearance. Here, we evaluate the effects of the sHsp Hsp22, as well as a pseudophosphorylated mutant and an N-terminal domain deletion (NTDΔ) variant on tau aggregation in vitro and tau accumulation and aggregation in cultured cells. Hsp22 wild-type (WT) protein had a significant inhibitory effect on heparin-induced aggregation in vitro and the pseudophosphorylated mutant Hsp22 demonstrated a similar effect. When co-expressed in a cell culture model with tau, these Hsp22 constructs significantly reduced soluble tau protein levels when transfected at a high ratio relative to tau. However, the Hsp22 NTDΔ protein drastically reduced the soluble protein expression levels of both tau WT and tau P301L/S320F even at lower transfection ratios, which resulted in a correlative reduction of the triton-insoluble tau P301L/S320F aggregates.
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Rank, Kenneth B., Adele M. Pauley, Keshab Bhattacharya, Zhigang Wang, David B. Evans, Timothy J. Fleck, Jennifer A. Johnston, and Satish K. Sharma. "Direct interaction of soluble human recombinant tau protein with Aβ 1-42 results in tau aggregation and hyperphosphorylation by tau protein kinase II." FEBS Letters 514, no. 2-3 (March 13, 2002): 263–68. http://dx.doi.org/10.1016/s0014-5793(02)02376-1.
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Zhao, Yanyan, Ole Tietz, Wei-Li Kuan, Abdul K. Haji-Dheere, Stephen Thompson, Benjamin Vallin, Elisabetta Ronchi, Gergely Tóth, David Klenerman, and Franklin I. Aigbirhio. "A fluorescent molecular imaging probe with selectivity for soluble tau aggregated protein." Chemical Science 11, no. 18 (2020): 4773–78. http://dx.doi.org/10.1039/c9sc05620c.
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Chatterjee, Shreyasi, Megan Sealey, Eva Ruiz, Chrysia M. Pegasiou, Keeley Brookes, Sam Green, Anna Crisford, et al. "Age-related changes in tau and autophagy in human brain in the absence of neurodegeneration." PLOS ONE 18, no. 1 (January 26, 2023): e0262792. http://dx.doi.org/10.1371/journal.pone.0262792.
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Tau becomes abnormally hyper-phosphorylated and aggregated in tauopathies like Alzheimers disease (AD). As age is the greatest risk factor for developing AD, it is important to understand how tau protein itself, and the pathways implicated in its turnover, change during aging. We investigated age-related changes in total and phosphorylated tau in brain samples from two cohorts of cognitively normal individuals spanning 19–74 years, without overt neurodegeneration. One cohort utilised resected tissue and the other used post-mortem tissue. Total soluble tau levels declined with age in both cohorts. Phosphorylated tau was undetectable in the post-mortem tissue but was clearly evident in the resected tissue and did not undergo significant age-related change. To ascertain if the decline in soluble tau was correlated with age-related changes in autophagy, three markers of autophagy were tested but only two appeared to increase with age and the third was unchanged. This implies that in individuals who do not develop neurodegeneration, there is an age-related reduction in soluble tau which could potentially be due to age-related changes in autophagy. Thus, to explore how an age-related increase in autophagy might influence tau-mediated dysfunctions in vivo, autophagy was enhanced in a Drosophila model and all age-related tau phenotypes were significantly ameliorated. These data shed light on age-related physiological changes in proteins implicated in AD and highlights the need to study pathways that may be responsible for these changes. It also demonstrates the therapeutic potential of interventions that upregulate turnover of aggregate-prone proteins during aging.
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Mroczko, Groblewska, and Litman-Zawadzka. "The Role of Protein Misfolding and Tau Oligomers (TauOs) in Alzheimer′s Disease (AD)." International Journal of Molecular Sciences 20, no. 19 (September 20, 2019): 4661. http://dx.doi.org/10.3390/ijms20194661.
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Although the causative role of the accumulation of amyloid β 1–42 (Aβ42) deposits in the pathogenesis of Alzheimer′s disease (AD) has been under debate for many years, it is supposed that the toxicity soluble oligomers of Tau protein (TauOs) might be also the pathogenic factor acting on the initial stages of this disease. Therefore, we performed a thorough search for literature pertaining to our investigation via the MEDLINE/PubMed database. It was shown that soluble TauOs, especially granular forms, may be the most toxic form of this protein. Hyperphosphorylated TauOs can reduce the number of synapses by missorting into axonal compartments of neurons other than axon. Furthermore, soluble TauOs may be also responsible for seeding Tau pathology within AD brains, with probable link to AβOs toxicity. Additionally, the concentrations of TauOs in the cerebrospinal fluid (CSF) and plasma of AD patients were higher than in non-demented controls, and revealed a negative correlation with mini-mental state examination (MMSE) scores. It was postulated that adding the measurements of TauOs to the panel of CSF biomarkers could improve the diagnosis of AD.
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Gyparaki, Melina Theoni, Arian Arab, Elena M. Sorokina, Adriana N. Santiago-Ruiz, Christopher H. Bohrer, Jie Xiao, and Melike Lakadamyali. "Tau forms oligomeric complexes on microtubules that are distinct from tau aggregates." Proceedings of the National Academy of Sciences 118, no. 19 (May 5, 2021): e2021461118. http://dx.doi.org/10.1073/pnas.2021461118.
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Tau is a microtubule-associated protein, which promotes neuronal microtubule assembly and stability. Accumulation of tau into insoluble aggregates known as neurofibrillary tangles (NFTs) is a pathological hallmark of several neurodegenerative diseases. The current hypothesis is that small, soluble oligomeric tau species preceding NFT formation cause toxicity. However, thus far, visualizing the spatial distribution of tau monomers and oligomers inside cells under physiological or pathological conditions has not been possible. Here, using single-molecule localization microscopy, we show that tau forms small oligomers on microtubules ex vivo. These oligomers are distinct from those found in cells exhibiting tau aggregation and could be precursors of aggregated tau in pathology. Furthermore, using an unsupervised shape classification algorithm that we developed, we show that different tau phosphorylation states are associated with distinct tau aggregate species. Our work elucidates tau’s nanoscale composition under nonaggregated and aggregated conditions ex vivo.
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Cowan, Catherine M., Shmma Quraishe, and Amritpal Mudher. "What is the pathological significance of tau oligomers?" Biochemical Society Transactions 40, no. 4 (July 20, 2012): 693–97. http://dx.doi.org/10.1042/bst20120135.
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Insoluble aggregates of the microtubule-associated protein tau characterize a number of neurodegenerative diseases collectively termed tauopathies. These aggregates comprise abnormally hyperphosphorylated and misfolded tau proteins. Research in this field has traditionally focused on understanding how hyperphosphorylated and aggregated tau mediates dysfunction and toxicity in tauopathies. Recent findings from both Drosophila and rodent models of tauopathy suggest that large insoluble aggregates such as tau filaments and tangles may not be the key toxic species in these diseases. Thus some investigators have shifted their focus to study pre-filament tau species such as tau oligomers and hyperphosphorylated tau monomers. Interestingly, tau oligomers can exist in a variety of states including hyperphosphorylated and unphosphorylated forms, which can be both soluble and insoluble. It remains to be determined which of these oligomeric states of tau are causally involved in neurodegeneration and which signal the beginning of the formation of inert/protective filaments. It will be important to better understand this so that tau-based therapeutic interventions can target the most toxic tau species.
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Yu, Hai-Yang, Dong-Mei Gao, Wei Zhou, Bing-Bing Xia, Zhi-Yuan He, Bo Wu, Min-Zhi Jiang, Ming-Li Wang, and Jun Zhao. "Expression, purification, and bioactivity of a soluble recombinant ovine interferon-tau in Escherichia coli." Journal of Veterinary Research 65, no. 1 (January 29, 2021): 101–8. http://dx.doi.org/10.2478/jvetres-2021-0011.
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Abstract Introduction Ovine interferon-tau (oIFN-τ) is a newly discovered type I interferon. This study used biochemical techniques to transform the oIFN-τ gene into Escherichia coli to obtain the mass and soluble expression of the recombinant protein. Material and Methods First, total RNA was extracted from fresh sheep embryonic tissues with TRIzol reagent and then used as a template to reverse transcribe and amplify the mature oIFN-τ gene with RT-PCR. The amplified product was next digested with the HindIII and XhoI restriction enzymes and inserted into the pET-32a(+) vector to construct the prokaryotic expression plasmid. The corrected in-frame recombinant plasmid, pET-32a(+)-oIFN-τ, was transformed into E. coli Rosetta (DE3) competent cells. After induction with isopropyl-beta-D-thiogalactopyranoside (IPTG), the recombinant protein was detected in bacteria. Finally, the bacteria were lysed by sonication, and the recombinant protein was purified by nickel affinity chromatography and DEAE anion exchange chromatography. Results The protein was confirmed to be oIFN-τ, which mainly existed in the soluble lysate fraction, as proven by SDS-PAGE and Western blot assays. Conclusion Purified IFN-τ exists mostly in a soluble form, and its anti-vesicular stomatitis virus (VSV) activity reached 7.08×10(6)IU/mL.
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Lin, Gaoping, Feiyan Zhu, Nicholas M. Kanaan, Rei Asano, Norimichi Shirafuji, Hirohito Sasaki, Tomohisa Yamaguchi, et al. "Clioquinol Decreases Levels of Phosphorylated, Truncated, and Oligomerized Tau Protein." International Journal of Molecular Sciences 22, no. 21 (November 8, 2021): 12063. http://dx.doi.org/10.3390/ijms222112063.
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The neuropathological hallmarks of Alzheimer’s disease (AD) are senile plaques (SPs), which are composed of amyloid β protein (Aβ), and neurofibrillary tangles (NFTs), which consist of highly phosphorylated tau protein. As bio-metal imbalance may be involved in the formation of NFT and SPs, metal regulation may be a direction for AD treatment. Clioquinol (CQ) is a metal-protein attenuating compound with mild chelating effects for Zn2+ and Cu2+, and CQ can not only detach metals from SPs, but also decrease amyloid aggregation in the brain. Previous studies suggested that Cu2+ induces the hyperphosphorylation of tau. However, the effects of CQ on tau were not fully explored. To examine the effects of CQ on tau metabolism, we used a human neuroblastoma cell line, M1C cells, which express wild-type tau protein (4R0N) via tetracycline-off (TetOff) induction. In a morphological study and ATP assay, up to 10 μM CQ had no effect on cell viability; however, 100 μM CQ had cytotoxic effects. CQ decreased accumulation of Cu+ in the M1C cells (39.4% of the control), and both total and phosphorylated tau protein. It also decreased the activity of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) (37.3% and 60.7% levels of the control, respectively), which are tau kinases. Of note, activation of protein phosphatase 2A (PP2A), which is a tau phosphatase, was also observed after CQ treatment. Fractionation experiments demonstrated a reduction of oligomeric tau in the tris insoluble, sarkosyl soluble fraction by CQ treatment. CQ also decreased caspase-cleaved tau, which accelerated the aggregation of tau protein. CQ activated autophagy and proteasome pathways, which are considered important for the degradation of tau protein. Although further studies are needed to elucidate the mechanisms responsible for the effects of CQ on tau, CQ may shed light on possible AD therapeutics.
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Vitali, Antonella, Alessandra Piccini, Roberta Borghi, Pantaleo Fornaro, Sandra L. Siedlak, Mark A. Smith, Pierluigi Gambetti, Bernardino Ghetti, and Massimo Tabaton. "Soluble amyloid β-protein is increased in frontotemporal dementia with tau gene mutations." Journal of Alzheimer's Disease 6, no. 1 (February 20, 2004): 45–51. http://dx.doi.org/10.3233/jad-2004-6106.
Full textDissertations / Theses on the topic "Soluble tau protein"
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Zamani, Marzieh. "The role of the JNK/AP-1 pathway in the induction of iNOS and CATs in vascular cells." Thesis, University of Hertfordshire, 2013. http://hdl.handle.net/2299/10626.
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Nitric oxide (NO) is an important biological molecule within the body, which over production of this molecule in response to different stimulations can cause various inflammatory diseases. Over production of this molecule is caused by the induction of the inducible nitric oxide synthase (iNOS) enzyme. This enzyme uses L-arginine as a substrate and therefore the presence and transport of this amino acid into the cells can be a key factor in regulating NO over production. Different signalling mechanisms have been implicated in the regulation of this pathway and one of which involves the Mitogen Activated Protein Kinases (MAPK). This family of proteins respond to inflammatory conditions and may mediate effects induced by inflammatory mediators. Of the MAPKs, the role of the c-Jun-N-terminal kinase (JNK) pathway in the induction of iNOS is still controversial. JNK and its downstream target, the transcription factor Activator Protein-1 (AP-1), have shown contradictory effects on iNOS induction leading to controversies over their role in regulating iNOS expression in different cell systems or with various stimuli. The studies described in this thesis have determined the role of JNK/AP-1 on iNOS expression, NO production, L-arginine uptake and also on the transporters responsible for L-arginine transport into the cells. The studies were carried out in two different cell types: rat aortic smooth muscle cells (RASMCs) and J774 macrophages which are both critically associated with the over production of NO in vascular inflammatory disease states. The first approach was to block the expression of the inducible L-arginine-NO pathway using SP600125 and JNK Inhibitor VIII which are both pharmacological inhibitors of JNK. The results from these studies showed that the pharmacological intervention was without effect in RASMCs, but inhibited iNOS, NO and L-arginine transport in J774 macrophages. In contrast, the molecular approach employed using two dominant negative constructs of AP-1 (TAM-67 and a-Fos) revealed a different profile of effects in RASMCs, where a-Fos caused an induction in iNOS and NO while TAM-67 had an inhibitory effect on iNOS, NO, L-arginine transport and CAT-2B mRNA expression. The latter was unaffected in RASMCs but suppressed in J774 macrophages by SP600125. Examination of JNK isoforms expression showed the presence of JNK1 and 2 in both cell systems. Moreover, stimulation with LPS/IFN- or LPS alone resulted in JNK phosphorylation which did not reveal any difference between smooth muscle cells and macrophages. In contrast, expression and activation of AP-1 subunits revealed differences between the two cell systems. Activation of cells with LPS and IFN- (RASMCs) or LPS alone (J774 macrophages) resulted in changes in the activated status of the different AP-1 subunit which was different for the two cell systems. In both cell types c-Jun, JunD and Fra-1 were increased and in macrophages, FosB activity was also enhanced. Inhibition of JNK with SP600125 caused down-regulation in c-Jun in both cell types. Interestingly this down-regulation was in parallel with increases in the subunits JunB, JunD, c-Fos and Fra-1 in RASMCs or JunB and Fra-1 in J774 macrophages. Since, SP600125 was able to exert inhibitory effects in the latter cell type but not in RASMCs, it is possible that the compensatory up-regulation of certain AP-1 subunits in the smooth muscle cells may compensate for c-Jun inhibition thereby preventing suppression of iNOS expression. This notion clearly needs to be confirmed but it is potentially likely that hetero-dimers formed between JunB, JunD, c-Fos and Fra-1 could sustain gene transcription in the absence of c-Jun. The precise dimer required has not been addressed but unlikely to exclusively involve JunB and Fra-1 as these are up-regulated in macrophages but did not sustain iNOS, NO or induced L-arginine transport in the presence of SP600125. To further support the argument above, the dominant negatives caused varied effects on the activation of the different subunits. a-Fos down-regulated c-Jun, c-Fos, FosB, Fra-1 whereas TAM-67 reduced c-Jun and c-Fos but marginally induced Fra-1 activity. Associated with these changes was an up-regulation of iNOS-NO by a-Fos and inhibition by TAM-67. Taken together, the data proposes a complex mechanism(s) that regulate the expression of the inducible L-arginine-NO pathway in different cell systems and the complexity may reflect diverse intracellular changes that may be different in each cell type and not always be apparent using one experimental approach especially where this is pharmacological. Moreover, these findings strongly suggest exercising caution when interpreting pure pharmacological findings in cell-based systems particularly where these are inconsistent or contradictory.
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Wu, Liangxing. "Design, Syntheses and Applications of Fluorescent Dyes." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-7012.
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New methodologies for the efficient syntheses of 4,4-difluoro-4-bora-3a,4adiaza-
s-indacenes (BODIPYs) and rosamines were developed. A serendipitous discovery
led to a new reaction which afforded BODIPYs in high yields. Systematic studies of the
kinetics and mechanisms of the new reaction were performed. A series of BODIPYs
were successfully prepared using the new approach. A simple and efficient synthesis of
rosamines with cyclic-amine substituents was devised. These new rosamines showed
interesting anti-tumor activities.
Several types of novel fluorescent compounds were prepared. Highly fluorescent
GFP-chromophore analogs were designed and synthesized. The correlation between the
optical properties and the structures was investigated. New pyronin dyes with mesoheteroatom
substituents were efficiently prepared. The fluorescence properties of these
compounds were highly dependent on the nature of the meso-substituents. A set of
BODIPY dyes that fluoresce brightly above 600 nm were made. They were then used as
acceptors to prepare water-soluble through-bond energy transfer cassettes. All the
cassettes had complete energy transfer and high quantum yields in MeOH. A few also
had good fluorescence properties in aqueous media and even on proteins.
The through-bond energy transfer cassettes were used to monitor protein-protein
interactions. In order to test our hypothesis, an artificial protein interaction system was
built by utilizing the biotin/(strept)avidin interactions. Thus Atto425-BSA-biotin,
streptavidin-cassette1 and avidin-cassette2 were prepared. The interactions between
Atto425-BSA-biotin and cassette labeled (strept)avidin were successfully detected in
vitro and in living cells by fluorescence techniques.
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Ponce, Christian. "Effects of Ruminally Degradable Nitrogen in Diets Containing Wet Distiller’s Grains with Solubles and Steam-flaked Corn on Feedlot Cattle Performance and Carcass Characteristics." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8572.
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Wet distiller’s grains with solubles are the most common feedstuff generated by the ethanol industry, and this feedstuff has been utilized by the feedlot industry. Exploration of the effect of dietary distiller’s inclusion on the form and quantity of protein or nitrogen (N) has received little attention. Assessment of degradable N needs in diets containing wet distiller’s grains with solubles (WDGS) is needed to aid the cattle feeding industry in managing feed costs and potential environmental issues. In Exp. 1, 525 yearling steers (initial weight = 373 ±13 kg) received treatments in a 2 × 3 1 factorial. Factors included corn WDGS (15 or 30 percent of DM) and non-protein N (NPN; 0, 1.5, or 3.0 percent of DM) from urea. The control diet without corn WDGS contained 3.0 percent NPN (1.06 percent urea) and cottonseed meal. Overall gain efficiency among steers fed 15 percent corn WDGS was greatest for 1.5 percent NPN and least for 0 percent NPN (P = 0.07, quadratic), whereas gain efficiency decreased linearly (P < 0.09) as NPN increased in the 30 percent WDGS. Dressing percent was greater (P < 0.01) for the control diet than for 15 percent or 30 percent WDGS. In Exp. 2, 296 steer calves (initial BW = 344 ± 12 kg) were adapted to a common finishing diet, blocked by BW, and assigned to treatments. Experimental diets included a control diet without WDGS (contained 3 percent NPN from urea, and cottonseed meal) and 15 percent WDGS with either 1.50, 2.25, or 3.00 percent NPN (0.52, 0.78, and 1.04 percent urea, respectively, on a DM basis). Overall gain efficiency on either a live or adjusted basis was not different among treatments (P > 0.15). Dietary NPN concentration did not influence growth performance (P > 0.21). Results suggest that optimum performance for cattle fed 15 percent WDGS occurred when the diet contained between 1.5 percent and 2.25 percent NPN. However, removing all supplemental NPN was necessary to support optimum performance in diets containing 30 percent WCDG.
Book chapters on the topic "Soluble tau protein"
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Mena, Raúl, and José Luna-Muñoz. "Stages of Pathological Tau-Protein Processing in Alzheimer’s Disease: From Soluble Aggregations to Polymerization into Insoluble Tau-PHFs." In Current Hypotheses and Research Milestones in Alzheimer's Disease, 79–91. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/978-0-387-87995-6_7.
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Molday, Laurie L., and Robert S. Molday. "1D4: A Versatile Epitope Tag for the Purification and Characterization of Expressed Membrane and Soluble Proteins." In Protein Affinity Tags, 1–15. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-1034-2_1.
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Taylor, Kathleen. "2. What causes dementia?" In Dementia: A Very Short Introduction, 24–50. Oxford University Press, 2020. http://dx.doi.org/10.1093/actrade/9780198825784.003.0002.
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‘What causes dementia?’ looks at the mechanisms underlying dementia. Dr Aloysius Alzheimer identified two key features in the brain. These were a build-up of plaques dominated by the amyloid-beta protein and tangled or misfolded tau proteins. How do we research the causes of dementia? Options include animal studies, human samples including stem cells and organoids, and improved neuroscience technologies such as brain scans and MRIs. Some scientists argue that smaller soluble oligomers are as dangerous as amyloid plaques, some continue to support the amyloid cascade theory, and others look elsewhere for advances and a possible cure. Theories beyond the amyloid hypothesis are receiving more funding, changing the focus of research.
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Seneci, Pierfausto. "Targets and Small Molecules Against Tauopathies. Part 1: From Genes to Soluble, Aggregation-Prone Tau Proteins." In Drug Design and Discovery in Alzheimer's Disease, 643–715. Elsevier, 2014. http://dx.doi.org/10.1016/b978-0-12-803959-5.50015-5.
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"Targets and Small Molecules Against Tauopathies. Part 1: From Genes to Soluble, Aggregation-Prone Tau Proteins." In Frontiers in Drug Design & Discovery, edited by Pierfausto Seneci, 643–715. BENTHAM SCIENCE PUBLISHERS, 2014. http://dx.doi.org/10.2174/9781608058228114060017.
Full textConference papers on the topic "Soluble tau protein"
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Chen, Kok Hao, and Jong Hyun Choi. "DNA Oligonucleotide-Templated Nanocrystals: Synthesis and Novel Label-Free Protein Detection." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11958.
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Semiconductor and magnetic nanoparticles hold unique optical and magnetic properties, and great promise for bio-imaging and therapeutic applications. As part of their stable synthesis, the nanocrystal surfaces are usually capped by long chain organic moieties such as trioctylphosphine oxide. This capping serves two purposes: it saturates dangling bonds at the exposed crystalline lattice, and it prevents irreversible aggregation by stabilizing the colloid through entropic repulsion. These nanocrystals can be rendered water-soluble by either ligand exchange or overcoating, which hampers their widespread use in biological imaging and biomedical therapeutics. Here, we report a novel scheme of synthesizing fluorescent PbS and magnetic Fe3O4 nanoparticles using DNA oligonucleotides. Our method of PbS synthesis includes addition of Na2S to the mixture solution of DNA sequence and Pb acetate (at a fixed molar ratio of DNA/S2−/Pb2+ of 1:2:4) in a standard TAE buffer at room temperature in the open air. In the case of Fe3O4 particle synthesis, ferric and ferrous chloride were mixed with DNA in DI water at a molar ratio of DNA/Fe2+/Fe3+ = 1:4:8 and the particles were formed via reductive precipitation, induced by increasing pH to ∼11 with addition of ammonium hydroxide. These nanocrystals are highly stable and water-soluble immediately after the synthesis, due to DNA termination. We examined the surface chemistry between oligonucleotides and nanocrystals using FTIR spectroscopy, and found that the different chemical moieties of nucleobases passivate the particle surface. Strong coordination of primary amine and carbonyl groups provides the chemical and colloidal stabilities, leading to high particle yields (Figure 1). The resulting PbS nanocrystals have a distribution of 3–6 nm in diameter, while a broader size distribution is observed with Fe3O4 nanoparticles as shown in Figure 1b and c, respectively. A similar observation was reported with the pH change-induced Fe3O4 particles of a bimodal size distribution where superparamagnetic and ferrimagnetic magnetites co-exist. In spite of the differences, FTIR measurements suggest that the chemical nature of the oligonucleotide stabilization in this case is identical to the PbS system. As a particular application, we demonstrate that aptamer-capped PbS QD can detect a target protein based on selective charge transfer, since the oligonucleotide-templated synthesis can also serve the additional purpose of providing selective binding to a molecular target. Here, we use thrombin and a thrombin-binding aptamer as a model system. These QD have diameters of 3∼6 nm and fluoresce around 1050 nm. We find that a DNA aptamer can passivate near IR fluorescent PbS nanocrystals, rendering them water-soluble and stable against aggregation, and retain the secondary conformation needed to selectively bind to its target, thrombin, as shown in Figure 2. Importantly, we find that when the aptamer-functionalized nanoparticles binds to its target (only the target), there is a highly systematic and selective quenching of the PL, even in high concentrations of interfering proteins as shown in Figure 3a and b. Thrombin is detected within one minute with a detection limit of ∼1 nM. This PL quenching is attributed to charge transfer from functional groups on the protein to the nanocrystals. A charge transfer can suppress optical transition mechanisms as we observe a significant decrease in QD absorption with target addition (Figure 3c). Here, we rule out other possibilities including Forster resonance energy transfer (FRET) and particle aggregation, because thrombin absorb only in the UV, and we did not observe any significant change in the diffusion coefficient of the particles with the target analyte, respectively. The charge transfer-induced photobleaching of QD and carbon nanotubes was observed with amine groups, Ru-based complexes, and azobenzene compounds. This selective detection of an unlabeled protein is distinct from previously reported schemes utilizing electrochemistry, absorption, and FRET. In this scheme, the target detection by a unique, direct PL transduction is observed even in the presence of high background concentrations of interfering negatively or positively charged proteins. This mechanism is the first to selectively modulate the QD PL directly, enabling new types of label free assays and detection schemes. This direct optical transduction is possible due to oligonucleotidetemplated surface passivation and molecular recognition. This chemistry may lead to more nanoparticle-based optical and magnetic probes that can be activated in a highly chemoselective manner.
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Byrdwell, William, and Hari Kiran Kotapati. "Fast chromatography with dual parallel mass spectrometry for lipidomic analysis and regioisomer quantification of pulse lipids." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/kxye7490.
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Pulses are seeds produced from legumes. More specifically, the United Nations Food and Agricultural Organization (FAO) defines pulses as “Leguminosae crops harvested exclusively for their grain, including dry beans, peas and lentilsâ€. This excludes oilseeds, such as soybeans and peanuts. Pulses are well known for their high content of protein and fiber. Most pulses do not contain a lot of oil, and there is not abundant information in the literature on pulse oil triglycerides, or triacylglycerols (TAGs). But pulses are consumed in large quantities in diets around the globe, so even lower amounts of oil in highly consumed pulses means that the composition of the pulse oil is important to the normal diet. We developed a 10-minute method for analysis of pulse oils using fast UHPLC for separation followed by dual parallel mass spectrometry (MS) for detection and quantification of the separated TAGs. Atmospheric pressure photoionization (APPI) MS was used for fat-soluble vitamin (FSV) quantification and for TAG regioisomer quantification and electrospray ionization (ESI) coupled to high-resolution accurate-mass (HRAM) MS was used for lipidomic identification and quantification of TAG molecular species and regioisomers. Calibration standards contained low levels of FSVs, but high levels of TAGs for better quantification of the bulk oil extracted by the Folch method. The TAG calibration standards were comprised of two different regioisomers, representing alternating concentration levels, thereby allowing fragment ratio calibration curves of regioisomers to be constructed along with the normal quantification calibration curves (regioisomer calibration curve within each quantification calibration curve). We found that FSV calibration curves were linear with high correlation coefficients (r2), while TAG calibration curves were best modeled as power functions and gave lower correlation coefficients. The pulse TAGs were rich in polyunsaturated fatty acids, which further adds to the already well-known nutritional benefits of pulses.
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Jandrot-Perrus, M., D. Didry, M. C. Guillin, and A. T. Nurden. "CHEMICAL CROSS-LINKING OF HUMAN THROMBIN TO PLATELET MEMBRANE GLYCOPROTEIN Ib." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643629.
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The interaction of thrombin with proteins at the platelet surface was assessed by chemical cross-linking with the membrane impermeable reagents DTSSP and BS3. Washed platelets were incubated with 125I-α-thrombin, 125I-TLCK-inactivated α-thrombin or 125I-γ-thrombin, and then with 0.1 mM DTSSP or BS3. The pattern of 3H-labeled glycoproteins (GP) was only slightly modified, with no measurable loss of GPIb, lib, Ilia, V and IX. Thrombin was detected in high molecular weight complexes migrating at the top of a 3 % acrylamide stacking gel and at the tap of the separating gel (7 %). In addition, a complex of Mr : 240 000 has been characterized. This complex was formed with 0.5 to 50 nM thrombin, after a short incubation time (30 sec) with active thrombin as well as with TLCK-thrombin. Hirudin added in excess before the crosslinker inhibited its formation. After analysis of soluble extracts by crossed Immunoelectrophoresis against a rabbit anti-whole platelet serum, 3 precipitates were labelled, among them the GPIIb-Illa complex and the most intense, a precipitate in the position of GPIb. Immunoprecipitation of GPIb using a murine monoclonal antibody allowed the isolation of the 240 000 complex. This complex was not observed with platelets from a patient with the Bernard-Soulier syndrome or with chymatrypsin-treated platelets lacking the outer portion of the GPIb αchain. 1125I-γ-thrombin was unable to bind to GPIb and form sucha complex. In each of these three examples of a defective binding, of thrombin toGPIb, the pattern of platelet aggregation and release reaction are characterized b a prolonged lag phase. Our results confirm the ability of GPIb to bindα-thrombin and support a role for this interaction in governing, the velocity of the platelet response.
Reports on the topic "Soluble tau protein"
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Splitter, Gary, Zeev Trainin, and Yacov Brenner. Lymphocyte Response to Genetically Engineered Bovine Leukemia Virus Proteins in Persistently Lymphocytic Cattle from Israel and the U.S. United States Department of Agriculture, July 1995. http://dx.doi.org/10.32747/1995.7570556.bard.
Full textAbstract:
The goal of this proposal was to identify proteins of BLV recognized by lymphocyte subpopulations and determine the contribution of these proteins to viral pathogenesis. Our hypothesis was that BLV pathogenesis is governed by the T-cell response and that the immune system likely plays an important role in controlling the utcome of infection. Our studies presented in ths final report demonstrate that T cell competency declines with advancing stages of infection. Dramatic differences were observed in lymphocyte proliferation to recombinant proteins encoded by BLV gag (p12, p15, and p24) and env (gp30 and gp15) genes in different disease stages. Because retroviruses are known to mutate frequently, examinatin of infected cattle from both Israel and the United States will likely detect variability in the immune response. This combined research approach provides the first opportunity to selectively address the importance of T-cell proliferation to BLV proteins and cytokines produced during different stages of BLV infection. Lack of this information regarding BLV infection has hindered understanding lympocyte regulation of BLV pathogenesis. We have developed the essential reagents necessary to determine the prominence of different lymphocyte subpopulations and cytokines produced during the different disease stages within the natural host. We found that type 1 cytokines (IL-2 and IFN-g) increased in PBMCs from animals in early disease, and decreasd in PBMCs from animals in late disease stages of BLV infection, while IL-10, increased with disease progression. Recently, a dichotomy between IL-12 and IL-10 has emerged in regards to progression of a variety of diseases. IL-12 activates type 1 cytokine production and has an antagonistic effect on type 2 cytokines. Here, using quantitative competitive PCR, we show that peripheral blood mononuclear cells from bovine leukemia virus infected animals in the alymphocytotic disease stage express increased amount of IL-12 p40 mRNA. In contrast, IL-12 p40 mRNA expression by PL animals was significantly decreased compared to normal and alymphocytotic animals. To examine the functions of these cytokines on BLV expression, BLV tax and pol mRNA expression and p24 protein production were quantified by competitive PCR, and by immunoblotting, respectively. IL-10 inhibited BLV tax and pol mRNA expression by BLV-infected PBMCs. In addition, we determined that macrophages secret soluble factor(s) that activate BLV expression, and that secretion of the soluble factor(s) could be inhibited by IL-10. In contrast, IL-2 increased BLV tax and pol mRNA, and p24 protein production. These findings suggest that macrophages have a key role in regulating BLV expression, and IL-10 produced by BLV-infected animals in late disease stages may serve to control BLV expression, while IL-2 in the early stage of disease may activate BLV expression. PGE2 is an important immune regulator produced only by macrophages, and is known to facilitate HIV replication. We hypothesized that PGE2 may regulate BLV expression. Here, we show that cyclooxygenase-2 (COX-2) mRNA expression was decreased in PBMCs treated with IL-10, while IL-2 enhanced COX-2 mRNA expression. In contrast, addition of PGE2 stimulated BLV tax and pol mRNA expression. In addition, the specific COX-2 inhibitor, NS-398, inhibited BLV expression, while addition of PGE2 increased BLV tax expression regardless of NS-398. These findings suggest that macrophage derived cyclooxygenase -2 products, such as PGE2, may regulate virus expression and disease rogression in BLV infection, and that cytokines (IL-2 and IL-10) may regulate BLV expression through PGE2 production.
2
Blumwald, Eduardo, and Avi Sadka. Sugar and Acid Homeostasis in Citrus Fruit. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7697109.bard.
Full textAbstract:
Citrus fruit quality standards have been determined empirically, depending on species and on the particular growing regions. In general, the TSS (total soluble solids) to total acidity (TA) ratio determines whether citrus fruit can be marketed. Soluble sugars account for most of the TSS during harvest while TA is determined almost solely by the citric acid content, which reaches levels of 1-5% by weight in many cultivated varieties. Acid and sugar homeostasis in the fruit is critical for the management of existing cultivars, the development of new cultivars, the improvement of pre- and post-harvest strategies and the control of fruit quality and disorders. The current proposal (a continuation of a previous proposal) aimed at: (1) completing the citrus fruit proteome and metabolome, and establish a citrus fruit functional database, (2) further characterization of the control of fruit acidity by studying the regulation of key steps affecting citrate metabolism, and determine the fate of citrate during acid decline stage, and (3) Studying acid and sugar homeostasis in citrus fruits by characterizing transport mechanisms across membranes. These aims were completed as the following: (1) Our initial efforts were aimed at the characterization and identification of citric acid transporters in citrus juice cells. The identification of citrate transporters at the vacuole of the citrus juice cell indicated that the steady-state citrate cytosolic concentration and the action of the cytosolic aconitase were key elements in establishing the pH homeostat in the cell that regulates the metabolic shift towards carbon usage in the fruit during the later stages of fruit development. We focused on the action of aconitase, the enzyme mediating the metabolic use of citric acid in the cells, and identified processes that control carbon fluxes in developing citrus fruits that control the fruit acid load; (2) The regulation of aconitase, catalyzing a key step in citrate metabolism, was further characterized by using two inhibitors, citramalte and oxalomalte. These compounds significantly increased citrate content and reduced the enzyme’s activity. Metabolite profiling and changes of amino-acid metabolizing enzymes in oxalomalate- treated cells suggested that the increase in citrate, caused by aconitase inhibition, induces amino acid synthesis and the GABA shunt, in accordance with the suggested fate of citrate during the acid decline stage in citrus fruit. (3) We have placed a considerable amount of time on the development of a citrus fruit proteome that will serve to identify all of the proteins in the juice cells and will also serve as an aid to the genomics efforts of the citrus research community (validating the annotation of the fruit genes and the different ESTs). Initially, we identified more than 2,500 specific fruit proteins and were able to assign a function to more than 2,100 proteins (Katz et al., 2007). We have now developed a novel Differential Quantitative LC-MS/MS Proteomics Methodology for the identification and quantitation of key biochemical pathways in fruits (Katz et al., 2010) and applied this methodology to identify determinants of key traits for fruit quality (Katz et al., 2011). We built “biosynthesis maps” that will aid in defining key pathways associated with the development of key fruit quality traits. In addition, we constructed iCitrus (http://wiki.bioinformatics.ucdavis.edu/index.php/ICitrus), a “functional database” that is essentially a web interface to a look-up table that allows users to use functional annotations in the web to identify poorly annotated citrus proteins. This resource will serve as a tool for growers and field extension specialists.