Artykuły w czasopismach: „Synthetic Oligomers”

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Bazaco, Raúl Blanco, José L. Segura i Carlos Seoane. "Recent advances in the design, synthesis and study of covalent conjugated oligomer–C60 ensembles". Collection of Czechoslovak Chemical Communications 74, nr 6 (2009): 857–86. http://dx.doi.org/10.1135/cccc2008218.

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This review presents an overview of the most recent results in the field of conjugated oligomer covalently attached to the C60 sphere focusing mainly on donor–conjugated oligomer–C60 triads and conjugated oligomer–multifullerene materials. Well-defined monodisperse oligomers as new materials that exhibit interesting optoelectronic properties have been the subject of intense study during the last decade. In this regard, a huge amount of work has been devoted to the development of new synthetic strategies toward the synthesis of conjugated oligomeric materials with precise length and constitution and to their chemical functionalization in order to incorporate them into more complex molecular and supramolecular architectures. An important area of research in the field of conjugated oligomers involves the design and synthesis of donor–acceptor ensembles by combination of monodisperse π-conjugated oligomeric systems with C60 fullerene. Such hybrid systems have shown excited-state interactions making them excellent candidates for fundamental photophysical studies. In addition, these materials have found applications in the field of photovoltaic devices. A review with 70 references.

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Kayama, Kotetsu, Hibiki Hashizume, Gerry Amor Camer i Daiji Endoh. "An improved gene synthesis method with asymmetric directions of oligonucleotides designed using a simulation program". BioTechniques 69, nr 3 (wrzesień 2020): 211–19. http://dx.doi.org/10.2144/btn-2020-0062.

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Artificial gene synthesis based on oligonucleotide augmentation is known as overlap extension PCR which generates a variety of intermediate synthetic products. The orientation and concentration of oligomers can be adjusted to reduce the synthesis of intermediates and optimize the full-length process of DNA synthesis, using a simulation program for serial oligomer extension. The efficiency of the serial oligomer extension process is predicted to be greatest when oligomers are in a ‘forward-reverse-reverse-reverse’ direction. Oligomers with such designed directions demonstrated generation of the desired product in the shortest time (number of cycles) by repeated annealing and elongation. This method, named Asymmetric Extension supported by a Simulator for Oligonucleotide Extension (AESOE), has shown efficiency and effectiveness with potentials for future improvements and optimal usage in DNA synthesis.

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Ali, Dildar, Zaheer Ahmed, Peter M. Kazmaier i Erwin Buncel. "Synthesis and characterization of low-molecular-weight azo-acetoxystyrene and azo-naphthalene oligomers via stable free radical polymerization (SFRP)". Canadian Journal of Chemistry 88, nr 9 (wrzesień 2010): 910–21. http://dx.doi.org/10.1139/v10-072.

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As an approach toward controlled molecular architecture through stable free radical polymerization (SFRP), we have prepared a series of oligomers of controlled molecular weights (Mn) and low polydispersities (structures 2 and 3, with n values ranging from 2 to 52). Definitive evidence of structure was obtained through MALDI/MS (inter-peak interval of 162 m/z in azo-acetoxystyrene oligomers 2 and 260 m/z in azo-naphthalene oligomers 3, which correspond to the acetoxystyrene (AS) and naphthalenic (Np) repeating units, with corroborative evidence from NMR and GPC. Two synthetic pathways were explored. Pathway 1 yields azo-acetoxystyrene oligomer 2 via SFR addition of a TEMPO-capped unimer 1 to acetoxystyrene. Subsequent reactions would convert 2 into 3. In an alternative pathway 2, SFR addition of 1 to 4-(1-methoxynaphthyl)styrene gives azo-naphthalene oligomer 3 directly. Thus, the present reported methodology for controlled architecture has achieved synthesis of oligomers from low Mn (chlorobenzene, PhCl, solvent) to relatively high Mn (bulk), with incorporation of naphthyl (donor) and azobenzene (acceptor) moieties, as well as spacer moieties, in a controlled manner.

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Pils, Marlene, Alexandra Dybala, Fabian Rehn, Lara Blömeke, Tuyen Bujnicki, Victoria Kraemer-Schulien, Wolfgang Hoyer, Detlev Riesner, Dieter Willbold i Oliver Bannach. "Development and Implementation of an Internal Quality Control Sample to Standardize Oligomer-Based Diagnostics of Alzheimer’s Disease". Diagnostics 13, nr 10 (11.05.2023): 1702. http://dx.doi.org/10.3390/diagnostics13101702.

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Protein misfolding and aggregation are pathological hallmarks of various neurodegenerative diseases. In Alzheimer’s disease (AD), soluble and toxic amyloid-β (Aβ) oligomers are biomarker candidates for diagnostics and drug development. However, accurate quantification of Aβ oligomers in bodily fluids is challenging because extreme sensitivity and specificity are required. We previously introduced surface-based fluorescence intensity distribution analysis (sFIDA) with single-particle sensitivity. In this report, a preparation protocol for a synthetic Aβ oligomer sample was developed. This sample was used for internal quality control (IQC) to improve standardization, quality assurance, and routine application of oligomer-based diagnostic methods. We established an aggregation protocol for Aβ1–42, characterized the oligomers by atomic force microscopy (AFM), and assessed their application in sFIDA. Globular-shaped oligomers with a median size of 2.67 nm were detected by AFM, and sFIDA analysis of the Aβ1–42 oligomers yielded a femtomolar detection limit with high assay selectivity and dilution linearity over 5 log units. Lastly, we implemented a Shewhart chart for monitoring IQC performance over time, which is another important step toward quality assurance of oligomer-based diagnostic methods.

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Orlov, Y. N. "The impact of the of cationic polyelectrolyte polymerization degree in latexes coagulation dosage of synthetic emulsion rubbers". Proceedings of the Voronezh State University of Engineering Technologies 81, nr 1 (18.07.2019): 318–24. http://dx.doi.org/10.20914/2310-1202-2019-1-318-324.

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The literature data on the parameters of coagulation of butadiene-styrene and butadiene-?-methyl styrene latexes by cationic polyelectrolytes in comparison with low-molecular ammonium compounds and nonionic polymers are discussed. The optimal dosage of cationic polyelectrolyte during coagulation of synthetic emulsion rubber latex stabilized by a combination of synthetic fatty acid Soaps and disproportionated rosin with a mixture of sodium salts of the oligomeric condensation product ?-naphthalenesulfonic acid with formaldehyde (Leukanol) is determined, ceteris paribus, by its degree of polymerization. The decrease in the optimum dosage during the transition from high molecular weight polyelectrolytes to the oligomers caused by decrease of the cationic and anionic groups ratio required for a complete binding Leukanol in the formation of oligomer-oligomer complexes compared with the polymer-oligomer complexes. This is due, apparently, the fact that an increase in the average molecular weight of the polyelectrolyte increases the proportion of so-called tails and loops, consisting of units of the polyelectrolyte that are not associated with molecules Leukanol

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Mao, Jialin, Wei Zhang, Stephen ZD Cheng i Chrys Wesdemiotis. "Analysis of monodisperse, sequence-defined, and POSS-functionalized polyester copolymers by MALDI tandem mass spectrometry". European Journal of Mass Spectrometry 25, nr 1 (luty 2019): 164–74. http://dx.doi.org/10.1177/1469066719828875.

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Monodisperse, sequence-defined polymers can be potentially used for digital data storage. This study reports the sequence analysis and differentiation of monodisperse polyester copolymers carrying side chains functionalized in a specific order by polyhedral oligomeric silsesquioxane (POSS) nanoparticles. Steglich esterification and succinic anhydride ring-opening chemistries were utilized iteratively to synthesize the intended sequences, which were characterized by matrix-assisted laser desorption ionization tandem mass spectrometry (MALDI-MS2). Isomeric oligomers were readily distinguished based on their different fragmentation patterns. The sequences embedded in the oligomers were decrypted by their specific backbone dissociation pathways. The robustness of using MALDI-MS2 as a sequencing method for monodisperse synthetic macromolecules was assessed and validated by the characterization of longer oligomers.

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Walsh, D. M., I. Klyubin, G. M. Shankar, M. Townsend, J. V. Fadeeva, V. Betts, M. B. Podlisny i in. "The role of cell-derived oligomers of Aβ in Alzheimer's disease and avenues for therapeutic intervention". Biochemical Society Transactions 33, nr 5 (26.10.2005): 1087–90. http://dx.doi.org/10.1042/bst0331087.

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Burgeoning evidence suggests that soluble oligomers of Aβ (amyloid β-protein) are the earliest effectors of synaptic compromise in Alzheimer's disease. Whereas most other investigators have employed synthetic Aβ peptides, we have taken advantage of a β-amyloid precursor protein-overexpressing cell line (referred to as 7PA2) that secretes sub-nanomolar levels of low-n oligomers of Aβ. These are composed of heterogeneous Aβ peptides that migrate on SDS/PAGE as dimers, trimers and tetramers. When injected into the lateral ventricle of rats in vivo, these soluble oligomers inhibit hippocampal long-term potentiation and alter the memory of a complex learned behaviour. Biochemical manipulation of 7PA2 medium including immunodepletion with Aβ-specific antibodies and fractionation by size-exclusion chromatography allowed us to unambiguously attribute these effects to low-n oligomers. Using this paradigm we have tested compounds directed at three prominent amyloid-based therapeutic targets: inhibition of the secretases responsible for Aβ production, inhibition of Aβ aggregation and immunization against Aβ. In each case, compounds capable of reducing oligomer production or antibodies that avidly bind Aβ oligomers also ameliorate the synaptotoxic effects of these natural, cell-derived oligomers.

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Urrego-Riveros, Sara, Matthias Bremer, Jonas Hoffmann, Anne Heitmann, Thibault Reynaldo, Janek Buhl, Paul J. Gates i in. "Conjugated oligomers with alternating heterocycles from a single monomer: synthesis and demonstration of electroluminescence". Organic Chemistry Frontiers 6, nr 21 (2019): 3636–43. http://dx.doi.org/10.1039/c9qo00947g.

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Núñez-Villanueva, Diego, i Christopher A. Hunter. "Controlled mutation in the replication of synthetic oligomers". Chemical Science 12, nr 11 (2021): 4063–68. http://dx.doi.org/10.1039/d0sc06770a.

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The use of two different covalent base-pairs introduces sequence mutations at a controlled rate in the covalent template-directed synthesis of oligotriazoles, a step towards evolvable synthetic polymers.

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Bianco, Alberto. "ChemInform Abstract: Combinatorial Synthetic Oligomers". ChemInform 32, nr 41 (24.05.2010): no. http://dx.doi.org/10.1002/chin.200141275.

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Bouchard, Jacob L., Taylor C. Davey i Todd M. Doran. "Aβ(M1–40) and Wild-Type Aβ40 Self-Assemble into Oligomers with Distinct Quaternary Structures". Molecules 24, nr 12 (15.06.2019): 2242. http://dx.doi.org/10.3390/molecules24122242.

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Amyloid-β oligomers (AβOs) self-assemble into polymorphic species with diverse biological activities that are implicated causally to Alzheimer’s disease (AD). Synaptotoxicity of AβO species is dependent on their quaternary structure, however, low-abundance and environmental sensitivity of AβOs in vivo have impeded a thorough assessment of structure–function relationships. We developed a simple biochemical assay to quantify the relative abundance and morphology of cross-linked AβOs. We compared oligomers derived from synthetic Aβ40 (wild-type (WT) Aβ40) and a recombinant source, called Aβ(M1–40). Both peptides assemble into oligomers with common sizes and morphology, however, the predominant quaternary structures of Aβ(M1–40) oligomeric states were more diverse in terms of dispersity and morphology. We identified self-assembly conditions that stabilize high-molecular weight oligomers of Aβ(M1–40) with apparent molecular weights greater than 36 kDa. Given that mixtures of AβOs derived from both peptides have been shown to be potent neurotoxins that disrupt long-term potentiation, we anticipate that the diverse quaternary structures reported for Aβ(M1–40) oligomers using the assays reported here will facilitate research efforts aimed at isolating and identifying common toxic species that contribute to synaptic dysfunction.

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Dondoni, Alessandro. "Formylation of carbohydrates and the evolution of synthetic routes to artificial oligosaccharides and glycoconjugates". Pure and Applied Chemistry 72, nr 9 (1.01.2000): 1577–88. http://dx.doi.org/10.1351/pac200072091577.

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A highly effective method for the synthesis of formyl C-glycosides is described via addition of 2-lithiothiazole or 2-lithiobenzothiazole to sugar lactones, deoxygenation of the resulting ketols, and releasing of the formyl group from the heterocyclic ring. The synthetic utility of these sugar aldehydes is demonstrated by the development of synthetic methods to more elaborate C-glycosides. These include various (1-6)-C-disaccharides and some higher oligomers up to a C,C,C,C-pentasaccharide; C-glycosyl amino acid isosteres of N-glycosyl asparagines; the methylene isostere of β-Δ-galactosyl ceramide; linear and cylic (2-1)-ketoside oligomers. An alternative synthesis of ethylene-bridged glycosyl asparagine isosteres is illustrated by the use of ethynyl C-glycosides as starting materials.

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Kravchenko, Kateryna, Andreas Kulawik, Maren Hülsemann, Katja Kühbach, Christian Zafiu, Yvonne Herrmann, Christina Linnartz i in. "Analysis of anticoagulants for blood-based quantitation of amyloid β oligomers in the sFIDA assay". Biological Chemistry 398, nr 4 (1.04.2017): 465–75. http://dx.doi.org/10.1515/hsz-2016-0153.

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Abstract Early diagnostics at the preclinical stage of Alzheimer’s disease is of utmost importance for drug development in clinical trials and prognostic guidance. Since soluble Aβ oligomers are considered to play a crucial role in the disease pathogenesis, several methods aim to quantify Aβ oligomers in body fluids such as cerebrospinal fluid (CSF) and blood plasma. The highly specific and sensitive method surface-based fluorescence intensity distribution analysis (sFIDA) has successfully been established for oligomer quantitation in CSF samples. In our study, we explored the sFIDA method for quantitative measurements of synthetic Aβ particles in blood plasma. For this purpose, EDTA-, citrate- and heparin-treated blood plasma samples from five individual donors were spiked with Aβ coated silica nanoparticles (Aβ-SiNaPs) and were applied to the sFIDA assay. Based on the assay parameters linearity, coefficient of variation and limit of detection, we found that EDTA plasma yields the most suitable parameter values for quantitation of Aβ oligomers in sFIDA assay with a limit of detection of 16 fM.

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Zeisig, Bernd B., Colin Kwok, Amanda J. Wilson, Arthur Zelent, Hinrich Gronemeyer, Shuo Dong i Chi Wai Eric So. "Recruitment of RXRα by Homo-Oligomeric RARα Is a Key for RARα-Mediated Transformation." Blood 108, nr 11 (16.11.2006): 360. http://dx.doi.org/10.1182/blood.v108.11.360.360.

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Abstract Chimeric fusion proteins involving Retinoic Acid Receptor Alpha (RARα) invariantly associate with almost 100% of Acute Promyelocytic Leukemia (APL). While we and others have recently demonstrated an essential role of aberrant self-association in RARα fusions mediated transformation1,2, forced oligomerization of truncated transcription factors including MLL3 and AML14 has emerged as an important oncogenic property shared by these most common chimeric fusion proteins involved in AML. To further characterize the underlying mechanisms and its modes of action, the present study dissects the essential molecular properties and transformation mechanisms by oligomeric RARα-oncoproteins. Firstly, we define the oncogenic threshold of self-association by showing that homo-oligomerization rather than homo-dimerization is required for Stat5b-RARα mediated transformation of primary hematopoietic cells. Although constitutive transcriptional repression is believed to be the underlying mechanism for RARα-mediated transformation, oligomeric RARα fusion proteins can bind retinoic acid response elements (RAREs) either as homo-oligomers or higher order hetero-oligomers with RXRα. To gain further insights into the transcriptional control mediated by RARα fusions, we successfully constructed various Stat5b-RARα point mutants that maintained the homo-oligomerization properties but lost their abilities to bind DNA as homo-oligomers. These resulting mutants could still efficiently transform primary hematopoietic cells in spite of their lack of homo-oligomeric DNA binding ability. To investigate if this is unique to Stat5b-RARα or is a general phenomena that can also apply to other RARα fusions, we further demonstrated that the synthetic FKBP-RARα fusion, which closely mimick both biochemical and transformation properties of bona fide RARα fusion proteins, was incapable of binding DNA as homo-oligomers, suggesting that homo-oligomeric DNA-binding is dispensable for RARα-mediated transformation. Conversely we reveal that the higher-order RARα-fusion/RXRα hetero-oligomeric complex, which aberrantly recruits transcriptional co-repressor SMRT, represents the major functional DNA-binding module. Specific knockdown of RXRα expression using shRNA approach can suppress transformation mediated by both bona fide and synthetic RARα fusion proteins, thus indicating a critical functional role of RXRα in RARα-mediated transformation of primary hematopoietic cells. Finally to assess the possible therapeutic values of targeting RXRα-mediated pathways in RARα-mediated transformation, we also demonstrated specific inhibition of myeloid transformation mediated by various RARα oncoproteins using the panRXR-selective agonist, SR11237. Taken together, these results not only highlight the functional significance of higher-order RARα-fusion/RXRα hetero-oligomeric complex, but also attest RXRα as a potential therapeutic target for APL.

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Vastl, Julian, Rendy Kartika, Kichul Park, Art E. Cho i David A. Spiegel. "Peptidines: glycine-amidine-based oligomers for solution- and solid-phase synthesis". Chemical Science 7, nr 5 (2016): 3317–24. http://dx.doi.org/10.1039/c5sc03882k.

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Cheung, David L. "Aggregation of an Amyloidogenic Peptide on Gold Surfaces". Biomolecules 13, nr 8 (18.08.2023): 1261. http://dx.doi.org/10.3390/biom13081261.

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Solid surfaces have been shown to affect the aggregation and assembly of many biomolecular systems. One important example is the formation of protein fibrils, which can occur on a range of biological and synthetic surfaces. The rate of fibrillation depends on both the protein structure and the surface chemistry, with the different molecular and oligomer structures adopted by proteins on surfaces likely to be crucial. In this paper, the aggregation of the model amyloidogenic peptide, Aβ(16–22), corresponding to a hydrophobic segment of the amyloid beta protein on a gold surface is studied using molecular dynamics simulation. Previous simulations of this peptide on gold surfaces have shown that it adopts conformations on surfaces that are quite different from those in bulk solution. These simulations show that this then leads to significant differences in the oligomer structures formed in solution and on gold surfaces. In particular, oligomers formed on the surface are low in beta-strands so are unlike the structures formed in bulk solution. When oligomers formed in solution adsorb onto gold surfaces they can then restructure themselves. This can then help explain the inhibition of Aβ(16–22) fibrillation by gold surfaces and nanoparticles seen experimentally.

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Stross, Alexander E., Giulia Iadevaia i Christopher A. Hunter. "Cooperative duplex formation by synthetic H-bonding oligomers". Chemical Science 7, nr 1 (2016): 94–101. http://dx.doi.org/10.1039/c5sc03414k.

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Pugacheva, Inna N., Nadezhda S. Nikulina i Sergey S. Nikulin. "TECHNOLOGICAL ASPECT OF PRODUCTION AND USE OF OIL-OLIGOMERIC ADDITIVE ON BASIS OF SECONDARY OLIGOMERS IN PRODUCTION OF EMULSION RUBBER". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 61, nr 4-5 (17.04.2018): 105. http://dx.doi.org/10.6060/tcct.20186104-05.5688.

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The paper shows the perspective direction of using by-products and wastes of the petrochemical industry in the production of rubber products. It was revealed that oligomers synthesized from petrochemical by-products can be used as promising additives. The technological aspects of the use of additives based on PN-6 oil and its combination with an oligomer synthesized from by-products of polybutadiene production in the technology of obtaining filled emulsion rubbers were studied. It has been found that the best way to combine oligomeric additives with the matrix of synthetic rubbers is to introduce them into latex in the form of dispersions. The influence of coagulants of different nature on the process of emulsion rubber release filled with oil oligomeric anthioxidant dispersion was investigated. It was found that the change in the mass ratio of oil-oligomeric-anthioxidant dispersion components did not significantly affect the consumption of the coagulant used. It has been shown that the introduction of an oil-oligomeric-anthioxidant additive into the elastomeric compositions at the stage of their creation provides an even distribution of the components in the rubber matrix. The effect of manufactured additives on the properties of the resulting composites was estimated. It has been found that vulcanizates obtained on the basis of rubber with a high content of oligomeric component in the composition of the additive have a higher resistance to thermal oxidative aging. Increasing the stability of vulcanizates to the thermal and oxidative effects indicates a decrease in the losses of the antioxidant in the process of obtaining rubbers and elastomeric compositions. It is shown that the introduction of oily oligomerically antioxidant dispersion in latex at the stage of creation of elastomeric compositions makes it possible to improve the technical and economic efficiency and environmental friendliness of their production. Evaluation of the effect of manufactured oligomeric additives on the properties of the resulting composites revealed their multifunctionality.Forcitation:Pugacheva I.N., Nikulina N.S., Nikulin S.S. Technological aspect of production and use of oil-oligomeric additive on basis of secondary oligomers in production of emulsion rubber. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 105-110

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Sancesario, Giulia M., Marzia Nuccetelli, Andrea Cerri, Joshua Zegeer, Cinzia Severini, Maria T. Ciotti, Massimo Pieri i in. "Bromelain Degrades Aβ1-42 Monomers and Soluble Aggregates: An In Vitro Study in Cerebrospinal Fluid of Alzheimer’s Disease Patients". Current Alzheimer Research 15, nr 7 (9.05.2018): 628–36. http://dx.doi.org/10.2174/1567205015666180123124851.

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Background: Therapeutic approaches targeting amyloid β42 (Aβ42) oligomers may represent a promising neuroprotective strategy for the prevention and treatment of Alzheimer's disease (AD). Objective: In this study we evaluated the ability of bromelain, a plant cysteine protease derived from pineapple stems, to interact with synthetic Aβ42 monomers and oligomers. We also examined the ability of bromelain to interfere in vitro with synthetic Aβ42 aggregates in the cerebrospinal fluid (CSF) of Alzheimer's disease as well as of control patients affected by other neurological diseases. Method: Both synthetic monomers and aggregates of Aβ42 were incubated in CSF with varying concentrations of bromelain. The effects of digestion were evaluated by Western Blot analysis using the specific monoclonal antibody 4G8 to identify the patterns of residual content of Aβ42. We further used rat primary cortical culture neurons (CN) to examine the cytotoxic action of this natural compound. Results: We found that bromelain successfully degraded Aβ42 monomers and low and high molecular weight oligomers. Indeed, when bromelain preparations of 3 and 6 mU were added to the CSF, the residual amount of Aβ42 monomers and oligomers were significantly reduced when compared to the same standard Aβ42 preparations incubated in CSF without bromelain. Moreover, bromelain incubations of 0.1, 0.5, and 1 mU/ml were not toxic to CN, as compared to vehicle treated cells. Conclusion: Overall, these results represent an important insight into the action of bromelain on Aβ42 oligomers, suggesting its potential use in the therapy of AD.

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Galzitskaya, Oxana. "New Mechanism of Amyloid Fibril Formation". Current Protein & Peptide Science 20, nr 6 (20.05.2019): 630–40. http://dx.doi.org/10.2174/1389203720666190125160937.

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Polymorphism is a specific feature of the amyloid structures. We have studied the amyloid structures and the process of their formation using the synthetic and recombinant preparations of Aβ peptides and their three fragments. The fibrils of different morphology were obtained for these peptides. We suppose that fibril formation by Aβ peptides and their fragments proceeds according to the simplified scheme: destabilized monomer → ring-like oligomer → mature fibril that consists of ringlike oligomers. We are the first who did 2D reconstruction of amyloid fibrils provided that just a ringlike oligomer is the main building block in fibril of any morphology, like a cell in an organism. Taking this into account it is easy to explain the polymorphism of fibrils as well as the splitting of mature fibrils under different external actions, the branching and inhomogeneity of fibril diameters. Identification of regions in the protein chains that form the backbone of amyloid fibril is a direction in the investigation of amyloid formation. It has been demonstrated for Aβ(1-42) peptide and its fragments that their complete structure is inaccessible for the action of proteases, which is an evidence of different ways of association of ring-like oligomers with the formation of fibrils. Based on the electron microscopy and mass spectrometry data, we have proposed a molecular model of the fibril formed by both Aβ peptide and its fragments. In connection with this, the unified way of formation of fibrils by oligomers, which we have discovered, could facilitate the development of relevant fields of medicine of common action.

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Balducci, Claudia, Marten Beeg, Matteo Stravalaci, Antonio Bastone, Alessandra Sclip, Emiliano Biasini, Laura Tapella i in. "Synthetic amyloid-β oligomers impair long-term memory independently of cellular prion protein". Proceedings of the National Academy of Sciences 107, nr 5 (19.01.2010): 2295–300. http://dx.doi.org/10.1073/pnas.0911829107.

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Inability to form new memories is an early clinical sign of Alzheimer’s disease (AD). There is ample evidence that the amyloid-β (Aβ) peptide plays a key role in the pathogenesis of this disorder. Soluble, bio-derived oligomers of Aβ are proposed as the key mediators of synaptic and cognitive dysfunction, but more tractable models of Aβ−mediated cognitive impairment are needed. Here we report that, in mice, acute intracerebroventricular injections of synthetic Aβ1–42 oligomers impaired consolidation of the long-term recognition memory, whereas mature Aβ1–42 fibrils and freshly dissolved peptide did not. The deficit induced by oligomers was reversible and was prevented by an anti-Aβ antibody. It has been suggested that the cellular prion protein (PrPC) mediates the impairment of synaptic plasticity induced by Aβ. We confirmed that Aβ1–42 oligomers interact with PrPC, with nanomolar affinity. However, PrP-expressing and PrP knock-out mice were equally susceptible to this impairment. These data suggest that Aβ1–42 oligomers are responsible for cognitive impairment in AD and that PrPC is not required.

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Gabrielli, Luca, i Christopher A. Hunter. "Supramolecular catalysis by recognition-encoded oligomers: discovery of a synthetic imine polymerase". Chemical Science 11, nr 28 (2020): 7408–14. http://dx.doi.org/10.1039/d0sc02234a.

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Núñez-Villanueva, Diego, i Christopher A. Hunter. "Replication of Sequence Information in Synthetic Oligomers". Accounts of Chemical Research 54, nr 5 (6.02.2021): 1298–306. http://dx.doi.org/10.1021/acs.accounts.0c00852.

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Ohmori, Ken, Tomohiro Shono, Yuki Hatakoshi, Takahisa Yano i Keisuke Suzuki. "Integrated Synthetic Strategy for Higher Catechin Oligomers". Angewandte Chemie International Edition 50, nr 21 (25.02.2011): 4862–67. http://dx.doi.org/10.1002/anie.201007473.

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Ohmori, Ken, Tomohiro Shono, Yuki Hatakoshi, Takahisa Yano i Keisuke Suzuki. "Integrated Synthetic Strategy for Higher Catechin Oligomers". Angewandte Chemie 123, nr 21 (25.02.2011): 4964–69. http://dx.doi.org/10.1002/ange.201007473.

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Sable, Ganesh A., Kang Ju Lee i Hyun-Suk Lim. "Solid-Phase Synthesis and Circular Dichroism Study of β-ABpeptoids". Molecules 24, nr 1 (5.01.2019): 178. http://dx.doi.org/10.3390/molecules24010178.

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The development of peptidomimetic foldamers that can form well-defined folded structures is highly desirable yet challenging. We previously reported on α-ABpeptoids, oligomers of N-alkylated β2-homoalanines and found that due to the presence of chiral methyl groups at α-positions, α-ABpeptoids were shown to adopt folding conformations. Here, we report β-ABpeptoids having chiral methyl group at β-positions rather than α-positions as a different class of peptoids with backbone chirality. We developed a facile solid-phase synthetic route that enables the synthesis of β-ABpeptoid oligomers ranging from 2-mer to 8-mer in excellent yields. These oligomers were shown to adopt ordered folding conformations based on circular dichroism (CD) and NMR studies. Overall, these results suggest that β-ABpeptoids represent a novel class of peptidomimetic foldamers that will find a wide range of applications in biomedical and material sciences.

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Wuttke, André, Sebastian Nils Fischer, Annika Nebel, Michael Marsch i Armin Geyer. "Improved δ-valerolactam templates for the assembly of Aβ-miniamyloids by boronic ester formation". Organic & Biomolecular Chemistry 14, nr 22 (2016): 5032–48. http://dx.doi.org/10.1039/c6ob00565a.

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Hoyas Pérez, Nadia, i James E. M. Lewis. "Synthetic strategies towards mechanically interlocked oligomers and polymers". Organic & Biomolecular Chemistry 18, nr 35 (2020): 6757–80. http://dx.doi.org/10.1039/d0ob01583k.

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Kim, DaWon, Jeong Hwa Lee, Hye Yun Kim, Jisu Shin, Kyeonghwan Kim, Sejin Lee, Jinwoo Park, JinIkyon Kim i YoungSoo Kim. "Fluorescent indolizine derivative YI-13 detects amyloid-β monomers, dimers, and plaques in the brain of 5XFAD Alzheimer transgenic mouse model". PLOS ONE 15, nr 12 (23.12.2020): e0243041. http://dx.doi.org/10.1371/journal.pone.0243041.

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Alzheimer disease (AD) is a neurodegenerative disorder characterized by the aberrant production and accumulation of amyloid-β (Aβ) peptides in the brain. Accumulated Aβ in soluble oligomer and insoluble plaque forms are considered to be a pathological culprit and biomarker of the disorder. Here, we report a fluorescent universal Aβ-indicator YI-13, 5-(4-fluorobenzoyl)-7,8-dihydropyrrolo[1,2-b]isoquinolin-9(6H)-one, which detects Aβ monomers, dimers, and plaques. We synthesized a library of 26 fluorescence chemicals with the indolizine core and screen them through a series of in vitro tests utilizing Aβ as a target and YI-13 was selected as the final imaging candidate. YI-13 was found to stain and visualize insoluble Aβ plaques in the brain tissue, of a transgenic mouse model with five familial AD mutations (5XFAD), by a histochemical approach and to label soluble Aβ oligomers within brain lysates of the mouse model under a fluorescence plate reader. Among oligomers aggregated from monomers and synthetic dimers from chemically conjugated monomers, YI-13 preferred the dimeric Aβ.

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Li, Jie, Maxime Leclercq, Mathieu Fossepré, Mathieu Surin, Karine Glinel, Alain M. Jonas i Antony E. Fernandes. "Discrete multifunctional sequence-defined oligomers with controlled chirality". Polymer Chemistry 11, nr 24 (2020): 4040–46. http://dx.doi.org/10.1039/d0py00537a.

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Ota, Yusuke, Toshiki Murayama i Kyoko Nozaki. "One-step catalytic asymmetric synthesis of all-syn deoxypropionate motif from propylene: Total synthesis of (2R,4R,6R,8R)-2,4,6,8-tetramethyldecanoic acid". Proceedings of the National Academy of Sciences 113, nr 11 (23.02.2016): 2857–61. http://dx.doi.org/10.1073/pnas.1518898113.

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In nature, many complex structures are assembled from simple molecules by a series of tailored enzyme-catalyzed reactions. One representative example is the deoxypropionate motif, an alternately methylated alkyl chain containing multiple stereogenic centers, which is biosynthesized by a series of enzymatic reactions from simple building blocks. In organic synthesis, however, the majority of the reported routes require the syntheses of complex building blocks. Furthermore, multistep reactions with individual purifications are required at each elongation. Here we show the construction of the deoxypropionate structure from propylene in a single step to achieve a three-step synthesis of (2R,4R,6R,8R)-2,4,6,8-tetramethyldecanoic acid, a major acid component of a preen-gland wax of the graylag goose. To realize this strategy, we focused on the coordinative chain transfer polymerization and optimized the reaction condition to afford a stereo-controlled oligomer, which is contrastive to the other synthetic strategies developed to date that require 3–6 steps per unit, with unavoidable byproduct generation. Furthermore, multiple oligomers with different number of deoxypropionate units were isolated from one batch, showing application to the construction of library. Our strategy opens the door for facile synthetic routes toward other natural products that share the deoxypropionate motif.

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Rosa-Gastaldo, Daniele, Vytautas Pečiukėnas, Christopher A. Hunter i Luca Gabrielli. "Duplex vs. folding: tuning the self-assembly of synthetic recognition-encoded aniline oligomers". Organic & Biomolecular Chemistry 19, nr 41 (2021): 8947–54. http://dx.doi.org/10.1039/d1ob01882e.

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Xu, Zhanjie, Peng Du, Peter Meiser i Claus Jacob. "Proanthocyanidins: Oligomeric Structures with Unique Biochemical Properties and Great Therapeutic Promise". Natural Product Communications 7, nr 3 (marzec 2012): 1934578X1200700. http://dx.doi.org/10.1177/1934578x1200700321.

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Proanthocyanidins represent a unique class of oligomeric and polymeric secondary metabolites found ubiquitously and in considerable amounts in plants and some algae. These substances exhibit a range of rather surprising physical and chemical properties which, once applied to living organisms, are translated into a multitude of biological activities. The latter include antioxidant properties, cancer chemoprevention, anti-inflammatory and anti-diabetic effects as well as some exceptional, yet highly interesting activities, such as anti-nutritional and antimicrobial activity. Despite the wide range of activities and possible medical/agricultural applications of proanthocyanidins, many questions still remain, including issues related to bioavailability, metabolism and the precise biochemical, extra- and intracellular targets and mode(s) of action of these highly potent materials. Among the various physical and chemical interactions of such substances, strong binding to proteins appears to form the basis of many of their biological activities. Once easy-to-use synthetic methods to produce appropriate quantities of pure proanthocyanidins are available, it will be possible to identify the prime biological targets of these oligomers, study oligomer-protein interactions in more detail and develop possible practical applications in medicine and agriculture.

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Vyas, Sandip B., i Lawrence K. Duffy. "Equilibration of a Synthetic Alzheimer 6-Protein Analog, 622-35, During RP-HPLC". Protein & Peptide Letters 3, nr 2 (kwiecień 1996): 89–94. http://dx.doi.org/10.2174/092986650302220614093454.

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Abstract: The 1322-35 peptide (mol wt 1345 Da) of the Alzheimer 13-protein, AI3P, eluted as a series of oligomers during reversed-phase high-perfonriance liquid chromatography. Four distinct oligomers were resolved on the reversed phase surface, whereas size-exclusion chromatography indicated a single component with an approximate mol wt of 11kDa which suggested that the peptide existed as an octamer in solution.

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Striepe, Laura, Marcus Vespa i Thomas Baumgartner. "Synthesis and properties of electron accepting star-shaped phosphaviologen oligomers". Organic Chemistry Frontiers 4, nr 5 (2017): 717–23. http://dx.doi.org/10.1039/c6qo00872k.

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Furusho, Yoshio, i Eiji Yashima. "Development of synthetic double helical polymers and oligomers". Journal of Polymer Science Part A: Polymer Chemistry 47, nr 20 (15.10.2009): 5195–207. http://dx.doi.org/10.1002/pola.23596.

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Lehnherr, Dan, i Rik R. Tykwinski. "Conjugated Oligomers and Polymers Based on Anthracene, Tetracene, Pentacene, Naphthodithiophene, and Anthradithiophene Building Blocks". Australian Journal of Chemistry 64, nr 7 (2011): 919. http://dx.doi.org/10.1071/ch11169.

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Acene derivatives provide unique materials for organic semiconductor applications. Recent synthetic achievements have provided several oligomers and polymers based on acene building blocks of varied structural motifs, including anthracene, tetracene, pentacene, as well as naphtho- and anthradithiophene. This report highlights recent work in this area, particularly for the higher acenes tetracene, pentacene, and anthradithiophene. When possible, the properties of defined-length oligomers are compared and contrasted to those of mono- and polymeric systems.

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de la Torre, Beatriz G., i Ramon Eritja. "Synthesis of labelled PNA oligomers by a post-synthetic modification approach". Bioorganic & Medicinal Chemistry Letters 13, nr 3 (luty 2003): 391–93. http://dx.doi.org/10.1016/s0960-894x(02)00994-0.

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Sato, Toyohiro, Yoshiaki Ohi, Daisuke Kato, Masayuki Mizuno, Hiroshi Takase, Tetsuko Kanamori, Cesar V. Borlongan, Akira Haji i Noriyuki Matsukawa. "Hippocampal Cholinergic Neurostimulating Peptide as a Possible Modulating Factor against Glutamatergic Neuronal Disability by Amyloid Oligomers". Cell Transplantation 26, nr 9 (wrzesień 2017): 1542–50. http://dx.doi.org/10.1177/0963689717721232.

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Despite having pathological changes in the brain associated with Alzheimer's disease (AD), some patients have preserved cognitive function. A recent epidemiological study has shown that diet, exercise, cognitive training, and vascular risk monitoring interventions may reduce cognitive decline in at-risk elderly people in the general population. However, the details of molecular mechanisms underlying this cognitive function preservation are still unknown. Previous reports have demonstrated that enriched environments prevent the impairment of hippocampal long-term potentiation (LTP) through β2-adrenergic signals, when LTP is incompletely suppressed by synthetic amyloid-β (Aβ) oligomers. The cholinergic network from the medial septal nucleus (MSN) is also a main modulating system for hippocampal glutamatergic neural activation through nicotinergic and/or muscarinergic acetylcholine receptors. Previously, we reported the importance of a cholinergic regulator gene in the MSN, hippocampal cholinergic neurostimulating peptide (HCNP). By using hippocampal sections from mice, we here demonstrated that the cholinergic neural activation from the MSN enhanced the glutamatergic neuronal activity during unsaturated LTP but not during saturated LTP. Synthetic Aβ oligomers suppressed the hippocampal glutamatergic activity in a concentration-dependent manner. Furthermore, HCNP, as well as a cholinergic agonist acting through the muscarinic M1 receptor, prevented the suppression of hippocampal glutamatergic neuronal activity induced by synthetic Aβ oligomers. This result suggests that the persisting cholinergic activation might be a potential explanation for the individual differences in cognitive effects of AD pathological changes.

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Fujiwara, Yoshiki, i Hitoshi Tamiaki. "Stereoselective self-aggregation of synthetic zinc 31-epimeric bacteriochlorophyll-d analogs possessing a methylene group at the 132-position as models of green photosynthetic bacterial chlorosomes". Photochemical & Photobiological Sciences 18, nr 5 (2019): 1218–27. http://dx.doi.org/10.1039/c8pp00535d.

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Synthetic bacteriochlorophyll-d analogs with the 13²-methylene group enhanced their 3¹-stereochemically controlled self-aggregation abilities and the stabilities of their resulting large oligomers.

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Blovský, Tomáš, Karel Šindelka, Zuzana Limpouchová i Karel Procházka. "Changes in Ion Concentrations upon the Binding of Short Polyelectrolytes on Phospholipid Bilayers: Computer Study Addressing Interesting Physiological Consequences". Polymers 14, nr 17 (2.09.2022): 3634. http://dx.doi.org/10.3390/polym14173634.

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This computer study was inspired by the experimental observation of Y. Qian et al. published in ACS Applied Materials and Interfaces, 2018 that the short positively charged β-peptide chains and their oligomeric analogues efficiently suppress severe medical problems caused by antimicrobial drug-resistant bacteria despite them not penetrating the bacterial membrane. Our coarse-grained molecular dynamics (dissipative particle dynamics) simulations confirm the tentative explanation of the authors of the experimental study that the potent antimicrobial activity is a result of the entropically driven release of divalent ions (mainly magnesium ions essential for the proper biological function of bacteria) into bulk solution upon the electrostatic binding of β-peptides to the bacterial membrane. The study shows that in solutions containing cations Na+, Ca2+ and Mg2+, and anions Cl−, the divalent cations preferentially concentrate close to the membrane and neutralize the negative charge. Upon the addition of positively charged oligomer chains (models of β-peptides and their analogues), the oligomers electrostatically bind to the membrane replacing divalent ions, which are released into bulk solvent. Our simulations indicate that the entropy of small ions (which controls the behavior of synthetic polyelectrolyte solutions) plays an important role in this and also in other similar biologically important systems.

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Zhang, Lei, Ling-Yan Jiang, Ke Zheng, Hua Duan, Min Li i Yuan-Chen Cui. "Enzymatic Synthesis of p-Cresol Oligomers and Evaluation of their Free Radical Scavenging Activity". Australian Journal of Chemistry 68, nr 2 (2015): 282. http://dx.doi.org/10.1071/ch13734.

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An environmentally benign aqueous micelle system was successfully used as reaction medium to perform enzymatic polymerization of p-cresol using horseradish peroxidase as catalyst. The polymerization maintains high yield over a wide pH range from 5 to 10. The resulting polymer is completely soluble in common solvent such as acetone, THF, DMF, and DMSO. Infrared spectroscopy analysis shows that polymer chains are composed of phenylene and oxyphenylene units. The formation of p-cresol polymer is according to a mechanism of free radical step polymerization. Because quinone structures are formed at the end of the molecular chain, p-cresol oligomers with an average degree of polymerization of less than 10 are obtained. p-Cresol oligomers possess several advantages such as simple synthetic route, good stability in air, and no significant smell. Importantly, the structure of p-cresol oligomers is similar to that of polyphenolic compounds in natural plants. As a result, p-cresol oligomers show good free radical scavenging activity and good prospects as novel antioxidant.

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Wang, Peng, Filippa Lo Cascio, Jia Gao, Rakez Kayed i Xuefei Huang. "Binding and neurotoxicity mitigation of toxic tau oligomers by synthetic heparin like oligosaccharides". Chemical Communications 54, nr 72 (2018): 10120–23. http://dx.doi.org/10.1039/c8cc05072d.

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Matos, Ana M., Joana S. Cristóvão, Dmitry V. Yashunsky, Nikolay E. Nifantiev, Ana S. Viana, Cláudio M. Gomes i Amélia P. Rauter. "Synthesis and effects of flavonoid structure variation on amyloid-β aggregation". Pure and Applied Chemistry 89, nr 9 (28.08.2017): 1305–20. http://dx.doi.org/10.1515/pac-2017-0201.

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AbstractDietary flavonoids and synthetic derivatives have a well-known potential for biomedical applications. In this perspective, we report herein new methodologies to access chrysin and 5,7-dihydroxychromone, and these structures were combined with those of naturally occurring quercetin, luteolin, (+)-dihydroquercetin and apigenin to assemble a set of polyphenols with structure variations for in vitro testing over the aggregation of Alzheimer’s disease (AD) amyloid peptide Aβ1−42. Using thioflavin-T (ThT) monitored kinetics and subsequent mechanistic analysis by curve fitting, we show that catechol-type flavonoids reduce Aβ1−42 fibril content by 30% at molar ratios over 10. Without affecting secondary nucleation, these compounds accelerate primary nucleation events responsible for early primary oligomer formation, putatively redirecting the latter into off-pathway aggregates. Atomic force microscopy (AFM) imaging of reaction end-points allowed a comprehensive topographical analysis of amyloid aggregate populations formed in the presence of each compound. Formation of Aβ1−42 small oligomers, regarded as the most toxic amyloid structures, seems to be limited by flavonoids with a C2 phenyl group, while flavonol 3-OH is not a beneficial structural feature. Overall, the diversity of structural variations within flavonoids opens avenues for their development as chemical tools in the treatment of AD by tackling the formation and distribution of neurotoxic oligomers species.

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Duan, Chaofeng, Lu Shen, Yuqing Guo, Xiaogang Wang, Xiaohua Wang i Zhixian Hao. "SERRS Detection on Silver Nanoparticles Supported on Acid-Treated Melamine-Resin Microspheres". Nanomaterials 11, nr 5 (19.05.2021): 1337. http://dx.doi.org/10.3390/nano11051337.

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Melamine-resin microspheres were synthesized at a pH of 4.0 for 20 min and used as silver nanoparticle (AgNP) carriers for surface enhanced resonant Raman scattering (SERRS) detection. An acetic acid–treatment reaction was introduced into the fabrication of the final substrate. The SERRS performance of the substrate was effectively optimized by regulating excess formaldehyde and experimental parameters, such as acidity, number of treatments and reaction temperature in the acid-treatment reaction. Based on the SERRS detection, it was declared that a trace amount of oligomers with a certain degree of polymerization is necessary for the construction of SERRS hotspots. In addition, it is important to remove excess oligomers with reference to the synthetic reaction of the polymer materials, given the special role of oligomers and the wide application of polymer materials in SERRS detection.

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Southcott, Mark, Mike Amone, James Senger, Andy Wang, Amy Polio i C. H. Sheppard. "The development of processable, fully imidized, polyimides for high-temperature applications". High Performance Polymers 6, nr 1 (luty 1994): 1–12. http://dx.doi.org/10.1088/0954-0083/6/1/001.

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Novel end-capped, fully imidized polyimides have been developed as potential high-performance matrix materials for advanced composites. This study describes the synthetic development of norbornene-capped oligomers, subsequent screening of neat resin mechanical and thermo-oxidative properties and, finally, composite property evaluation. It is shown that these soluble reactive oligomers can be prepared reproducibly and give crosslinked networks that have mechanical properties more typical of thermoplastics, as well as good hot/wet and thermo-oxidative stability. Composites were prepared using a cure cycle more characteristic of thermosetting-type polyimides and it was demonstrated that fully imidized polyimides allow low-void-content laminate manufacture via autoclave processing. The evolution of imidization volatiles, which are generated using the more common PMR- and polyamic-acid-type systems, is averted using these reactive oligomers.

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Dossi, Eleftheria, Jacob Earnshaw, Laurence Ellison, Gabriella Rabello dos Santos, Hamish Cavaye i Douglas J. Cleaver. "Understanding and controlling the glass transition of HTPB oligomers". Polymer Chemistry 12, nr 17 (2021): 2606–17. http://dx.doi.org/10.1039/d1py00233c.

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In this paper, we use a combination of experiment and simulation to achieve enhanced levels of synthetic control on the microstructure of the much-used binder material hydroxyl terminated polybutadiene (HTPB).

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Schwarzacher, Trude, i J. S. Heslop-Harrison. "In situ hybridization to plant telomeres using synthetic oligomers". Genome 34, nr 3 (1.06.1991): 317–23. http://dx.doi.org/10.1139/g91-052.

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The distribution of telomeric repeats in Hordeum vulgare (barley) and Secale cereale (rye) was studied by DNA–DNA in situ hybridization to root-tip chromosome preparations. Biotinylated synthetic oligomers, (TTTAGGG)6 and (CCCTAAA)6, homologous to the consensus sequence of the Arabidopsis thaliana telomeric repeat, were used as probes, and hybridization sites were detected by Texas red fluorescence or horseradish peroxidase catalyzed precipitation of diaminobenzidine. After examination in the light microscope, the same preparations were transferred to the electron microscope for high-resolution analysis. Sites of hybridization were visualized as single or double dots at the end of most chromosome arms. The sizes of the signal dots varied widely, indicating that individual telomeres may contain different numbers of repeats of the telomeric sequence. In contrast to many mammals, no telomere repeats were detected other than at the ends of the chromosomes. At interphase, signals were concentrated in one region of the nucleus, as would be expected from the Rabl orientation typical for dividing cells from cereal root tips.Key words: barley, rye, nuclear architecture, DNA–DNA in situ hybridization, telomeres.

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John, E., i F. Jähnig. "A synthetic analogue of melittin aggregates in large oligomers". Biophysical Journal 63, nr 6 (grudzień 1992): 1536–43. http://dx.doi.org/10.1016/s0006-3495(92)81737-x.

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Adamus, Grazyna, Piotr Kurcok, Iza Radecka i Marek Kowalczuk. "Bioactive oligomers from natural polyhydroxyalkanoates and their synthetic analogues". Polimery 62, nr 04 (kwiecień 2017): 317–22. http://dx.doi.org/10.14314/polimery.2017.317.

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