Artykuły w czasopismach: „Fibring”

1

Zanardo, Alberto, Amilcar Sernadas i Cristina Sernadas. "Fibring: completeness preservation". Journal of Symbolic Logic 66, nr 1 (marzec 2001): 414–39. http://dx.doi.org/10.2307/2694931.

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AbstractA completeness theorem is established for logics with congruence endowed with general semantics (in the style of general frames). As a corollary, completeness is shown to be preserved by fibring logics with congruence provided that congruence is retained in the resulting logic. The class of logics with equivalence is shown to be closed under fibring and to be included in the class of logics with congruence. Thus, completeness is shown to be preserved by fibring logics with equivalence and general semantics. An example is provided showing that completeness is not always preserved by fibring ligics endowed with standard (non general) semantics. A categorial characterization of fibring is provided using coproducts and cocartesian liftings.

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Gabbay, Dov M. "Fibring Argumentation Frames". Studia Logica 93, nr 2-3 (17.11.2009): 231–95. http://dx.doi.org/10.1007/s11225-009-9217-y.

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Sernadas, Cristina, João Rasga i Walter A. Carnielli. "Modulated fibring and the collapsing problem". Journal of Symbolic Logic 67, nr 4 (grudzień 2002): 1541–69. http://dx.doi.org/10.2178/jsl/1190150298.

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AbstractFibring is recognized as one of the main mechanisms in combining logics, with great significance in the theory and applications of mathematical logic. However, an open challenge to fibring is posed by the collapsing problem: even when no symbols are shared, certain combinations of logics simply collapse to one of them, indicating that fibring imposes unwanted interconnections between the given logics. Modulated fibring allows a finer control of the combination, solving the collapsing problem both at the semantic and deductive levels. Main properties like soundness and completeness are shown to be preserved, comparison with fibring is discussed, and some important classes of examples are analyzed with respect to the collapsing problem.

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Rasga, J. "Fibring Labelled Deduction Systems". Journal of Logic and Computation 12, nr 3 (1.06.2002): 443–73. http://dx.doi.org/10.1093/logcom/12.3.443.

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Fernandez, V. L., i M. E. Coniglio. "Fibring in the Leibniz Hierarchy". Logic Journal of IGPL 15, nr 5-6 (26.09.2007): 475–501. http://dx.doi.org/10.1093/jigpal/jzm036.

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Coniglio, M. E. "Fibring Logics with Topos Semantics". Journal of Logic and Computation 13, nr 4 (1.08.2003): 595–624. http://dx.doi.org/10.1093/logcom/13.4.595.

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Krawczyk, Krzysztof Aleksander. "Fibring Epistemic and Temporal Logics". Logic and Logical Philosophy 29, nr 1 (5.03.2019): 195. http://dx.doi.org/10.12775/llp.2019.008.

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Carnielli, W., J. Rasga i C. Sernadas. "Preservation of Interpolation Features by Fibring". Journal of Logic and Computation 18, nr 1 (4.09.2007): 123–51. http://dx.doi.org/10.1093/logcom/exm061.

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Sernadas, A., C. Sernadas, J. Rasga i M. Coniglio. "On Graph-theoretic Fibring of Logics". Journal of Logic and Computation 19, nr 6 (5.07.2009): 1321–57. http://dx.doi.org/10.1093/logcom/exp024.

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Rasga, J., A. Sernadas i C. Sernadas. "Fibring as Biporting Subsumes Asymmetric Combinations". Studia Logica 102, nr 5 (17.11.2013): 1041–74. http://dx.doi.org/10.1007/s11225-013-9524-1.

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Sernadas, A. "Fibring Modal First-Order Logics: Completeness Preservation". Logic Journal of IGPL 10, nr 4 (1.07.2002): 413–51. http://dx.doi.org/10.1093/jigpal/10.4.413.

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Sernadas, A. "Fibring of logics as a categorial construction". Journal of Logic and Computation 9, nr 2 (1.04.1999): 149–79. http://dx.doi.org/10.1093/logcom/9.2.149.

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Wu, Yin, Min Jiang, Zhongqiang Huang, Fei Chao i Changle Zhou. "An NP-complete fragment of fibring logic". Annals of Mathematics and Artificial Intelligence 75, nr 3-4 (1.07.2015): 391–417. http://dx.doi.org/10.1007/s10472-015-9468-4.

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Fenn, R. "Fibring the complement of the Fenn-Rolfsen Link". Publicacions Matemàtiques 33 (1.07.1989): 383–90. http://dx.doi.org/10.5565/publmat_33289_14.

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Kielak, Dawid. "Residually finite rationally solvable groups and virtual fibring". Journal of the American Mathematical Society 33, nr 2 (24.12.2019): 451–86. http://dx.doi.org/10.1090/jams/936.

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Azevedo Scárdua, B. "Holomorphic Anosov systems, foliations and fibring complex manifolds". Dynamical Systems 18, nr 4 (grudzień 2003): 365–89. http://dx.doi.org/10.1080/14689360310001613620.

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Coniglio, M. E., A. Sernadas i C. Sernadas. "Preservation by fibring of the finite model property". Journal of Logic and Computation 21, nr 2 (8.07.2010): 375–402. http://dx.doi.org/10.1093/logcom/exq022.

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Cruz-Filipe, L., A. Sernadas i C. Sernadas. "Heterogeneous Fibring of Deductive Systems Via Abstract Proof Systems". Logic Journal of IGPL 16, nr 2 (25.09.2007): 121–53. http://dx.doi.org/10.1093/jigpal/jzm057.

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Martins, M. A., i G. Voutsadakis. "Malinowski modalization, modalization through fibring and the Leibniz hierarchy". Logic Journal of IGPL 21, nr 5 (2.07.2013): 836–52. http://dx.doi.org/10.1093/jigpal/jzt019.

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Coniglio, Marcelo Esteban. "Recovering a Logic from Its Fragments by Meta-Fibring". Logica Universalis 1, nr 2 (październik 2007): 377–416. http://dx.doi.org/10.1007/s11787-007-0019-6.

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Caleiro, Carlos, i Jaime Ramos. "From Fibring to Cryptofibring. A Solution to the Collapsing Problem". Logica Universalis 1, nr 1 (styczeń 2007): 71–92. http://dx.doi.org/10.1007/s11787-006-0004-5.

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Mosesson, MW, JP DiOrio, KR Siebenlist, JS Wall i JF Hainfeld. "Evidence for a second type of fibril branch point in fibrin polymer networks, the trimolecular junction". Blood 82, nr 5 (1.09.1993): 1517–21. http://dx.doi.org/10.1182/blood.v82.5.1517.1517.

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Abstract Fibrin molecules polymerize to double-stranded fibrils by intermolecular end-to-middle domain pairing of complementary polymerization sites, accompanied by fibril branching to form a clot network. Mass/length measurements on scanning transmission electron microscopic images of fibrils comprising branch points showed two types of junctions. Tetramolecular junctions occur when two fibrils converge, creating a third branch with twice the mass/length of its constituents. Newly recognized trimolecular junctions have three fibril branches of equal mass/length, and occur when an extraneous fibrin molecule initiates branching in a propagating fibril by bridging across two unpaired complementary polymerization sites. When trimolecular junctions predominate, clots exhibit nearly perfect elasticity.

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Mosesson, MW, JP DiOrio, KR Siebenlist, JS Wall i JF Hainfeld. "Evidence for a second type of fibril branch point in fibrin polymer networks, the trimolecular junction". Blood 82, nr 5 (1.09.1993): 1517–21. http://dx.doi.org/10.1182/blood.v82.5.1517.bloodjournal8251517.

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Fibrin molecules polymerize to double-stranded fibrils by intermolecular end-to-middle domain pairing of complementary polymerization sites, accompanied by fibril branching to form a clot network. Mass/length measurements on scanning transmission electron microscopic images of fibrils comprising branch points showed two types of junctions. Tetramolecular junctions occur when two fibrils converge, creating a third branch with twice the mass/length of its constituents. Newly recognized trimolecular junctions have three fibril branches of equal mass/length, and occur when an extraneous fibrin molecule initiates branching in a propagating fibril by bridging across two unpaired complementary polymerization sites. When trimolecular junctions predominate, clots exhibit nearly perfect elasticity.

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24

Naumann, R. "A Fibring Semantic or the Semantic-Morphological Interface in Natural Language". Logic Journal of IGPL 10, nr 2 (1.03.2002): 191–226. http://dx.doi.org/10.1093/jigpal/10.2.191.

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Siebenlist, Kevin, Irene Hernandez, Joseph Wall, James Hainfeld i Michael Mosesson. "Fibrinogen Assembly and Crosslinking on a Fibrin Fragment E Template". Thrombosis and Haemostasis 87, nr 04 (2002): 651–58. http://dx.doi.org/10.1055/s-0037-1613062.

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SummaryThere is an ongoing controversy concerning whether crosslinked γ chains in fibrin are oriented “transversely” between fibril strands or “end-to-end” along fibril strands. From the latter viewpoint, Veklich et al. [Proc Natl Acad Sci (USA) 95: 1438, 1998] observed that fibrinogen fibrils that had been assembled on a fibrin fragment E template, crosslinked with factor XIIIa, and then dissociated in acetic acid solution, were aligned end-to-end. This led to the conclusion that crosslinked γ chains in fibrin under physiological conditions were also aligned endto-end. To assess its validity we studied the assembly and organization of fibrinogen molecules on a des AB-fibrin fragment E (E-des AB) or a des A-fibrin fragment E (E-des A) template.We evaluated the roles of E polymerization sites EA and EB, and D association sites γXL, Da, Db, βC, and αC in this process. EA:Da interactions caused fibrinogen: E “DED” complexes to form, and markedly enhanced the γ chain crosslinking rates of fibrinogen or des αC-fibrinogen. Fibrinogen crosslinking without added fibrin E was slower, and that of des αC-fibrinogen was still slower. These events showed that although αC domains promote fibrinogen fibril assembly and crosslinking, they contribute little to increasing the EA:Da-dependent crosslinking rate. Electron microscopic (STEM) images of E-des AB and fibrinogen plus factor XIIIa showed single-, double-, and multistranded fibrils with interstrand DED complexes aligned side-to-side. This alignment was due to βC:βC contacts resulting from D subdomain rearrangements initiated by the EB:Db interactions, and also occurred in mixtures of des αC-fibrinogen with E-des AB.In contrast, a mixture of fibrinogen and E-des A plus XIIIa revealed double-stranded fibrils with interstrand DED complexes in a halfstaggered arrangement, an alignment that we attribute to crosslinking of γXL sites bridging between fibrils strands. These and other features of E-des A-based fibrinogen fibrils, including interstrand γ chain bridges and early and extensive lateral fibril strand associations concomitant with accelerated γ chain crosslinking, indicate that crosslinking of fibrin fibril strands takes place preferentially on transversely positioned γ chains.

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DiOrio, J. P., M. W. Mosesson i M. Matsuda. "Fibrinogen Kurashiki (γ G268E) Fibrin Network Structure". Microscopy and Microanalysis 4, S2 (lipiec 1998): 1160–61. http://dx.doi.org/10.1017/s1431927600025927.

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Upon thrombin-catalyzed proteolytic conversion of fibrinogen to fibrin, fibrinopeptide A release exposes an N-terminal polymerization site (‘EA’) in the central E domain that interacts with a constitutive complementary site in each outer D domain (‘Da’) to drive the molecular assembly process by end-to-middle domain non-covalent ‘Da:EA’ interactions. End-to-end aligned doublestranded fibrils are formed in coordination with another recently described constitutive self-association site (termed ‘D:D’)that is situated at the outer end of each D domain. The D:D site contributes to end-to-end molecular alignment of fibrin molecules within each fibril strand. Concomitant branching and lateral fibril associations to form thick fibers, lead to formation of the mature fibrin clot.Fibrinogen ‘Kurashiki’ is a unique congenital dysfibrinogenemia that was identified in a homozygous father and his heterozygous son. The abnormality involves a γ chain amino acid mutation (γ G268E) and is characterized by delayed and abnormal fibrin polymerization.

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27

JANYŠKA, JOSEF, i MARCO MODUGNO. "HERMITIAN VECTOR FIELDS AND SPECIAL PHASE FUNCTIONS". International Journal of Geometric Methods in Modern Physics 03, nr 04 (czerwiec 2006): 719–54. http://dx.doi.org/10.1142/s0219887806001351.

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We start by analyzing the Lie algebra of Hermitian vector fields of a Hermitian line bundle. Then, we specify the base space of the above bundle by considering a Galilei, or an Einstein spacetime. Namely, in the first case, we consider, a fibred manifold over absolute time equipped with a spacelike Riemannian metric, a spacetime connection (preserving the time fibring and the spacelike metric) and an electromagnetic field. In the second case, we consider a spacetime equipped with a Lorentzian metric and an electromagnetic field. In both cases, we exhibit a natural Lie algebra of special phase functions and show that the Lie algebra of Hermitian vector fields turns out to be naturally isomorphic to the Lie algebra of special phase functions. Eventually, we compare the Galilei and Einstein cases.

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28

Kracht, Marcus. "Dov Gabbay. Fibring logics, Oxford Logic Guides, vol. 38. Oxford University Press, 1998, xiii + 475 pp." Bulletin of Symbolic Logic 10, nr 02 (czerwiec 2004): 209–11. http://dx.doi.org/10.1017/s1079898600003930.

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DiOrio, J. P., M. W. Mosesson, I. Hernandez, T. Sugo i M. Matsuda. "Fibrinogen Marburg Fibrin Network Structure". Microscopy and Microanalysis 5, S2 (sierpień 1999): 1120–21. http://dx.doi.org/10.1017/s1431927600018924.

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Fibrinogen is composed of three pairs of polypeptide chains, termed Aα, Bβ and γ, respectively. Proteolytic conversion of fibrinogen to fibrin by thrombin releases fibrinopeptide A and exposes an N-terminal polymerization site ('EA’) in the central E domain of the molecule. This site interacts with a constitutive complementary site in each outer D domain ('Da’) to drive the molecular assembly process by end-to-middle domain non-covalent ‘Da:EA’ interactions. End-to-end aligned double-stranded fibrils are formed in coordination with another recently described constitutive self-association site (termed ‘D:D’)fhat is situated at the outer end of each D domain. The D:D site contributes to end-to-end molecular alignment of fibrin molecules within each fibril strand. Concomitant branching and lateral fibril associations to form thick fibers, lead to formation of the mature fibrin clot.Fibrinogen Marburg is a homozygous hypodysfibrinogenemia lacking amino acid residues Aα461- 610 due to a stop codon at position 461 of the Aα chain.

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Voutsadakis, George. "Categorical Abstract Algebraic Logic: Meet-Combination of Logical Systems". Journal of Mathematics 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/126347.

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The widespread and rapid proliferation of logical systems in several areas of computer science has led to a resurgence of interest in various methods for combining logical systems and in investigations into the properties inherited by the resulting combinations. One of the oldest such methods isfibring. In fibring the shared connectives of the combined logics inherit properties frombothcomponent logical systems, and this leads often to inconsistencies. To deal with such undesired effects, Sernadas et al. (2011, 2012) have recently introduced a novel way of combining logics, calledmeet-combination, in which the combined connectives share only thecommonlogical properties they enjoy in the component systems. In their investigations they provide a sound and concretely complete calculus for the meet-combination based on available sound and complete calculi for the component systems. In this work, an effort is made to abstract those results to a categorical level amenable tocategorical abstract algebraic logictechniques.

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Edgell, Tracey, F. McEvoy, P. Webbon i P. J. Gaffney. "Monoclonal Antibodies to Human Fibrin: Interaction with other Animal Fibrins". Thrombosis and Haemostasis 75, nr 04 (1996): 595–99. http://dx.doi.org/10.1055/s-0038-1650328.

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SummaryFour monoclonal antibodies have previously been raised in our laboratory for possible use in thrombus imaging and the targeting of thrombolytic agents. These antibodies were raised to various human fibrin-related immunogens and each antibody had been selected for its specificity towards fibrin and not fibrinogen. To study further these antibodies in animal circulation models both in vivo and in vitro, their selectivity towards human fibrin as opposed to other animal fibrins was examined. In this study dissociation constants for each antibody with each of six species fibrins (human, baboon, pig, dog, sheep, and rabbit) were estimated using both fibrin clots and monolayers. Some limited data were also obtained with Sepharose-fibrin. Of the antibodies two (denoted 12B3B10 and 12B3A11) are seen to bind almost exclusively to human fibrin with dissociation constants of about 8 × 10−10 M using fibrin clots and monolayers. These same two mabs bound to baboon fibrin with a dissociation constant of 2 × 10−9 M, while neither displayed significant levels of binding to the fibrins from dog, pig, sheep and rabbit. The other two antibodies investigated (1H10 and 5F3) were found to bind well to fibrins of human, baboon, pig and dog, with dissociation constants in the range of 1.4-4.2 × 10−9 M. However neither 1H10 nor 5F3 displayed significant recognition of sheep and rabbit fibrins. Both 1H10 and 5F3 were also found by means of competitive ELISA’s to retain their selectivity to baboon, dog and pig fibrins in the presence of their respective fibrinogens.

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Repici, A., A. Sapino, G. Costamagna, M. Conio, C. De Angelis, A. Malesci, P. Preatoni, L. Laghi, G. Saracco i M. Rizzetto. "Fibring glue injection into the submucosa prior to EMR. An experimental study to evaluate different injection techniques". Digestive and Liver Disease 38 (kwiecień 2006): S9. http://dx.doi.org/10.1016/s1590-8658(06)80019-8.

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El Maachi, Ikram, Stavroula Kyriakou, Stephan Rütten, Alexander Kopp, Marius Köpf, Stefan Jockenhoevel i Alicia Fernández-Colino. "Silk Fibroin as Adjuvant in the Fabrication of Mechanically Stable Fibrin Biocomposites". Polymers 14, nr 11 (31.05.2022): 2251. http://dx.doi.org/10.3390/polym14112251.

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Fibrin is a very attractive material for the development of tissue-engineered scaffolds due to its exceptional bioactivity, versatility in the fabrication, affinity to cell mediators; and the possibility to isolate it from blood plasma, making it autologous. However, fibrin application is greatly limited due to its low mechanical properties, fast degradation, and strong contraction in the presence of cells. In this study, we present a new strategy to overcome these drawbacks by combining it with another natural polymer: silk fibroin. Specifically, we fabricated biocomposites of fibrin (5 mg/mL) and silk fibroin (0.1, 0.5 and 1% w/w) by using a dual injection system, followed by ethanol annealing. The shear elastic modulus increased from 23 ± 5 Pa from fibrin alone, to 67 ± 22 Pa for fibrin/silk fibroin 0.1%, 241 ± 67 Pa for fibrin/silk fibroin 0.5% and 456 ± 32 Pa for fibrin/silk fibroin 1%. After culturing for 27 days with strong contractile cells (primary human arterial smooth muscle cells), fibrin/silk fibroin 0.5% and fibrin/silk fibroin 1% featured minimal cell-mediated contraction (ca. 15 and 5% respectively) in contrast with the large surface loss of the pure fibrin scaffolds (ca. 95%). Additionally, the composites enabled the formation of a proper endothelial cell layer after culturing with human primary endothelial cells under standard culture conditions. Overall, the fibrin/silk fibroin composites, manufactured within this study by a simple and scalable biofabrication approach, offer a promising avenue to boost the applicability of fibrin in tissue engineering.

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DiOrio, J. P., K. R. Siebenlist, S. Terukina, K. Yamazumi, M. Matsuda i M. W. Mosesson. "The ultrastructure of fibrin prepared from fibrinogen ASAHI (γ 310 met→thr) and fibrinogen morioka (γ 275 arg→cys)". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1090–91. http://dx.doi.org/10.1017/s0424820100130080.

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Fibrinogen is composed of three pairs of polypeptide chains, termed Aα, Bβ and γ, respectively, covalently linked at their amino termini by disulfide bonds. Fibrinogen is proteolytically activated to fibrin monomer by thrombin which cleaves two A (FPA) and two B (FPB) fibrinopeptides from the respective N-termini of Aα, Bβ chains, each exposing a different type of polymerization site [“A” or “B”]. Exposure of either site leads to fibrin monomer assembly to form two-stranded fibrils with subsequent lateral fibril association to a branched three-dimensional fiber network. Fibrinogen Asahi is a congenital fibrinogen variant [γ310 Met → Thr] characterized by posttraumatic bleeding, a prolonged thrombin time, and abnormal fibrin polymerization. Asn at γ308 on the variant γ chain is glycosylated due to formation of a consensus sequence for glycosylation [Asn-Gly-Thr] that is created by the γ 310 Thr substitution. Fibrinogen Morioka is another congenital fibrinogen variant [γ 275 Arg→Cys] also characterized by defective fibrin polymerization.

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Chudzinski-Tavassi, Ana Marisa, Eva Maria Kelen, Ana Paula de Paula Rosa, Stephane Loyau, Claudio Sampaio, Cassian Bon i Eduardo Anglés-Cano. "Fibrino(geno)lytic Properties of Purified Hementerin, a Metalloproteinase from the Leech Haementeria depressa". Thrombosis and Haemostasis 80, nr 07 (1998): 155–60. http://dx.doi.org/10.1055/s-0037-1615155.

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SummaryThe fibrino(geno)lytic protein designated hementerin contained in crude extracts of the salivary complex of Haementeria depressa leeches was purified to apparent homogeneity by gel filtration, ion exchange chromatography and preparative SDS-PAGE. It is a single-chain 80 kDa, PhMeSO2F-resistant, calcium-dependent, metalloproteinase, which specifically degrades fibrin(ogen) through a plasminogen-independent pathway. The amino terminal sequence of 8 residues shows 80% similarity with hementin, another fibrino(geno)lytic protein purified from Haementeria ghilianii leeches. However, their activities differ somewhat in terms of kinetics and with regard to the structure of the fibrin(ogen) fragments they may produce. Cleavage by hementerin of fibrinogen Aα, γ and Bβ chains, in that order, produces 270 kDa to 67 kDa fragments which differ from those produced by plasmin. Hementerin was also able to degrade cross-linked fibrin although at a lower rate as compared to fibrinogen. In conclusion, hementerin is a plasminogen-independent fibrino(geno)lytic metalloproteinase that degrades fibrinogen faster than fibrin, prevents blood coagulation and destroys fibrin clots in vitro.

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Tuţă, Alexandra Mihaela, Valentin Daniel Sîrbu, Ioan Sîrbu i Ştefan Nichita. "Platelet rich fibrin (PRF) in oral implantology. Case study". Romanian Journal of Stomatology 61, nr 4 (31.12.2015): 271–76. http://dx.doi.org/10.37897/rjs.2015.4.3.

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Dental implant therapy based on osseointegration has known a big expansion in dentistry in the last years. Dental implant rehabilitation is a common procedure in restoring partial or total edentulous pacients in our days. A problem regarding implant rehabilitation appears when the pacient doesn’t have enought bone to allow implant insertion in safety conditions. In this cases the clinician has to turn to complementary interventions in order to improve bone width and height so that implants could be inserted. One of the most known procedures is guided bone regeneration (GBR – guided bone regeneration) wich consists in placing a membrane to the bone defects. Platelet rich fibrin (PRF – platelet rich fibrin) is a second generation platelet concentrate wich gives the clinician access to growth factors throught a simple and up to date technology. These growth factors wich are autologous, non-toxic and non-immunogenic enhance and accelerate normal bone regeneration pathways. (1)

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Siebenlist, Kevin R., Michael W. Mosesson, Irene Hernandez, Leslie A. Bush, Enrico Di Cera, John R. Shainoff, James P. Di Orio i Laurie Stojanovic. "Studies on the basis for the properties of fibrin produced from fibrinogen-containing γ′ chains". Blood 106, nr 8 (15.10.2005): 2730–36. http://dx.doi.org/10.1182/blood-2005-01-0240.

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AbstractHuman fibrinogen 1 is homodimeric with respect to its γ chains (`γA-γA'), whereas fibrinogen 2 molecules each contain one γA (γA1-411V) and one γ′ chain, which differ by containing a unique C-terminal sequence from γ′408 to 427L that binds thrombin and factor XIII. We investigated the structural and functional features of these fibrins and made several observations. First, thrombin-treated fibrinogen 2 produced finer, more branched clot networks than did fibrin 1. These known differences in network structure were attributable to delayed release of fibrinopeptide (FP) A from fibrinogen 2 by thrombin, which in turn was likely caused by allosteric changes at the thrombin catalytic site induced by thrombin exosite 2 binding to the γ′ chains. Second, cross-linking of fibrin γ chains was virtually the same for both types of fibrin. Third, the acceleratory effect of fibrin on thrombin-mediated XIII activation was more prominent with fibrin 1 than with fibrin 2, and this was also attributable to allosteric changes at the catalytic site induced by thrombin binding to γ′ chains. Fourth, fibrinolysis of fibrin 2 was delayed compared with fibrin 1. Altogether, differences between the structure and function of fibrins 1 and 2 are attributable to the effects of thrombin binding to γ′ chains.

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Meyer, Keith, Robert Smith i Eliot C. Williams. "Inhibition of Fibrin Polymerization by Serum Amyloid P Component and Heparin". Thrombosis and Haemostasis 57, nr 03 (1987): 345–48. http://dx.doi.org/10.1055/s-0038-1651131.

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SummaryThe effects of serum amyloid P component (SAP) and heparin on the thrombin-catalyzed formation of polymeric fibrin from purified fibrinogen were examined using a turbidometric method to quantify fibrin polymerization. SAP and heparin acted synergistically to inhibit the lateral aggregation of fibrin fibrils, resulting in the formation of fibrils with a smaller mass to length ratio. Heparin did not enhance the incorporation of SAP into fibrin clots, and the effect of heparin and SAP did not seem to be related to inhibition of thrombin or of fibrinopeptide release. The evidence suggests that a soluble complex of SAP and heparin inhibits fibrin polymerization.

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Sugo, Teruko, Chizuko Nakamikawa, Hiroshi Takano, Jun Mimuro, Shu-ichi Yamaguchi, Michael W. Mosesson, David A. Meh i in. "Fibrinogen Niigata With Impaired Fibrin Assembly: An Inherited Dysfibrinogen With a Bβ Asn-160 to Ser Substitution Associated With Extra Glycosylation at Bβ Asn-158". Blood 94, nr 11 (1.12.1999): 3806–13. http://dx.doi.org/10.1182/blood.v94.11.3806.

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Abstract A novel BβAsn-160 (TAA) to Ser (TGA) substitution has been identified in fibrinogen Niigata derived from a 64-year-old asymptomatic woman, who is heterozygotic for this abnormality. The mutation creates an Asn-X-Ser–type glycosylation sequence, and a partially sialylated biantennary oligosaccharide was linked to the BβAsn-158 residue. The functional abnormality was attributed to delayed lateral association of normally formed double-stranded protofibrils based on normal cross-linking of fibrin γ-chains and tissue-type plasminogen activator-catalyzed plasmin generation by polymerizing fibrin monomers. Enzymatic removal of all the N-linked oligosaccharides from fibrinogen Niigata accelerated fibrin monomer polymerization that reached the level of untreated normal fibrin monomers, but the thrombin time was prolonged from 18.2 seconds to 113 seconds (normal: 11.2 seconds to 8.9 seconds). By scanning electron micrographic analysis, Niigata fibrin fibers were found to be more curvilinear than normal fibrin fibers. After deglycosylation, Niigata fibers became straight being similar to untreated normal fibrin fibers, whereas normal deglycosylated fibrin appeared to be less-branched than untreated normal or deglycosylated Niigata fibrin. Although normal and Niigata fibrins were similar to each other in permeation and compaction studies, deglycosylated normal and Niigata fibrins had much higher permeability and compaction values, indicating that deglycosylation had brought about the formation of more porous networks. The enzymatic deglycosylation necessitates an Asn to Asp change at position Bβ-158 that is responsible for reducing the fiber thickness because of either local repulsive forces or steric hindrance in the coiled-coil region.

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40

Sugo, Teruko, Chizuko Nakamikawa, Hiroshi Takano, Jun Mimuro, Shu-ichi Yamaguchi, Michael W. Mosesson, David A. Meh i in. "Fibrinogen Niigata With Impaired Fibrin Assembly: An Inherited Dysfibrinogen With a Bβ Asn-160 to Ser Substitution Associated With Extra Glycosylation at Bβ Asn-158". Blood 94, nr 11 (1.12.1999): 3806–13. http://dx.doi.org/10.1182/blood.v94.11.3806.423a17_3806_3813.

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A novel BβAsn-160 (TAA) to Ser (TGA) substitution has been identified in fibrinogen Niigata derived from a 64-year-old asymptomatic woman, who is heterozygotic for this abnormality. The mutation creates an Asn-X-Ser–type glycosylation sequence, and a partially sialylated biantennary oligosaccharide was linked to the BβAsn-158 residue. The functional abnormality was attributed to delayed lateral association of normally formed double-stranded protofibrils based on normal cross-linking of fibrin γ-chains and tissue-type plasminogen activator-catalyzed plasmin generation by polymerizing fibrin monomers. Enzymatic removal of all the N-linked oligosaccharides from fibrinogen Niigata accelerated fibrin monomer polymerization that reached the level of untreated normal fibrin monomers, but the thrombin time was prolonged from 18.2 seconds to 113 seconds (normal: 11.2 seconds to 8.9 seconds). By scanning electron micrographic analysis, Niigata fibrin fibers were found to be more curvilinear than normal fibrin fibers. After deglycosylation, Niigata fibers became straight being similar to untreated normal fibrin fibers, whereas normal deglycosylated fibrin appeared to be less-branched than untreated normal or deglycosylated Niigata fibrin. Although normal and Niigata fibrins were similar to each other in permeation and compaction studies, deglycosylated normal and Niigata fibrins had much higher permeability and compaction values, indicating that deglycosylation had brought about the formation of more porous networks. The enzymatic deglycosylation necessitates an Asn to Asp change at position Bβ-158 that is responsible for reducing the fiber thickness because of either local repulsive forces or steric hindrance in the coiled-coil region.

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Karunarathne, Kanchana, Nabila Bushra, Olivia Williams, Imad Raza, Laura Tirado, Diane Fakhre, Fadia Fakhre i Martin Muschol. "Self-Assembly of Amyloid Fibrils Into 3D Gel Clusters Versus 2D Sheets". Biomolecules 13, nr 2 (24.01.2023): 230. http://dx.doi.org/10.3390/biom13020230.

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The deposition of dense fibril plaques represents the pathological hallmark for a multitude of human disorders, including many neurodegenerative diseases. Fibril plaques are predominately composed of amyloid fibrils, characterized by their underlying cross beta-sheet architecture. Research into the mechanisms of amyloid formation has mostly focused on characterizing and modeling the growth of individual fibrils and associated oligomers from their monomeric precursors. Much less is known about the mechanisms causing individual fibrils to assemble into ordered fibrillar suprastructures. Elucidating the mechanisms regulating this “secondary” self-assembly into distinct suprastructures is important for understanding how individual protein fibrils form the prominent macroscopic plaques observed in disease. Whether and how amyloid fibrils assemble into either 2D or 3D supramolecular structures also relates to ongoing efforts on using amyloid fibrils as substrates or scaffolds for self-assembling functional biomaterials. Here, we investigated the conditions under which preformed amyloid fibrils of a lysozyme assemble into larger superstructures as a function of charge screening or pH. Fibrils either assembled into three-dimensional gel clusters or two-dimensional fibril sheets. The latter displayed optical birefringence, diagnostic of amyloid plaques. We presume that pH and salt modulate fibril charge repulsion, which allows anisotropic fibril–fibril attraction to emerge and drive the transition from 3D to 2D fibril self-assembly.

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Hagg, Rupert, Peter Bruckner i Erik Hedbom. "Cartilage Fibrils of Mammals are Biochemically Heterogeneous: Differential Distribution of Decorin and Collagen IX". Journal of Cell Biology 142, nr 1 (13.07.1998): 285–94. http://dx.doi.org/10.1083/jcb.142.1.285.

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Cartilage fibrils contain collagen II as the major constituent, but the presence of additional components, minor collagens, and noncollagenous glycoproteins is thought to be crucial for modulating several fibril properties. We have examined the distribution of two fibril constituents—decorin and collagen IX—in samples of fibril fragments obtained after bovine cartilage homogenization. Decorin was preferentially associated with a population of thicker fibril fragments from adult articular cartilage, but was not present on the thinnest fibrils. The binding was specific for the gap regions of the fibrils, and depended on the decorin core protein. Collagen IX, by contrast, predominated in the population with the thinnest fibrils, and was scarce on wider fibrils. Double-labeling experiments demonstrated the coexistence of decorin and collagen IX in some fibrils of intermediate diameter, although most fibril fragments from adult cartilage were strongly positive for one component and lacked the other. Fibril fragments from fetal epiphyseal cartilage showed a different pattern, with decorin and collagen IX frequently colocalized on fragments of intermediate and large diameters. Hence, the presence of collagen IX was not exclusive for fibrils of small diameter. These results establish that articular cartilage fibrils are biochemically heterogeneous. Different populations of fibrils share collagen II, but have distinct compositions with respect to macromolecules defining their surface properties.

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Mosesson, MW, JP DiOrio, MF Muller, JR Shainoff, KR Siebenlist, DL Amrani, GA Homandberg, J. Soria, C. Soria i M. Samama. "Studies on the ultrastructure of fibrin lacking fibrinopeptide B (beta- fibrin)". Blood 69, nr 4 (1.04.1987): 1073–81. http://dx.doi.org/10.1182/blood.v69.4.1073.1073.

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Abstract Release of fibrinopeptide B from fibrinogen by copperhead venom procoagulant enzyme results in a form of fibrin (beta-fibrin) with weaker self-aggregation characteristics than the normal product (alpha beta-fibrin) produced by release of fibrinopeptides A (FPA) and B (FPB) by thrombin. We investigated the ultrastructure of these two types of fibrin as well as that of beta-fibrin prepared from fibrinogen Metz (A alpha 16 Arg----Cys), a homozygous dysfibrinogenemic mutant that does not release FPA. At 14 degrees C and physiologic solvent conditions (0.15 mol/L of NaCl, 0.015 mol/L of Tris buffer pH 7.4), the turbidity (350 nm) of rapidly polymerizing alpha beta-fibrin (thrombin 1 to 2 U/mL) plateaued in less than 6 min and formed a “coarse” matrix consisting of anastomosing fiber bundles (mean diameter 92 nm). More slowly polymerizing alpha beta-fibrin (thrombin 0.01 and 0.001 U/mL) surpassed this turbidity after greater than or equal to 60 minutes and concomitantly developed a network of thicker fiber bundles (mean diameters 118 and 186 nm, respectively). Such matrices also contained networks of highly branched, twisting, “fine” fibrils (fiber diameters 7 to 30 nm) that are usually characteristic of matrices formed at high ionic strength and pH. Slowly polymerizing beta-fibrin, like slowly polymerizing alpha beta-fibrin, displayed considerable quantities of fine matrix in addition to an underlying thick cable network (mean fiber diameter 135 nm), whereas rapidly polymerizing beta-fibrin monomer was comprised almost exclusively of wide, poorly anastomosed, striated cables (mean diameter 212 nm). Metz beta-fibrin clots were more fragile than those of normal beta-fibrin and were comprised almost entirely of a fine network. Metz fibrin could be induced, however, to form thick fiber bundles (mean diameter 76 nm) in the presence of albumin at a concentration (500 mumol/L) in the physiologic range and resembled a Metz plasma fibrin clot in that regard. The diminished capacity of Metz beta-fibrin to form thick fiber bundles may be due to impaired use or occupancy of a polymerization site exposed by FPB release. Our results indicate that twisting fibrils are an inherent structural feature of all forms of assembling fibrin, and suggest that mature beta-fibrin or alpha beta-fibrin clots develop from networks of thin fibrils that have the ability to coalesce to form thicker fiber bundles.

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Mosesson, MW, JP DiOrio, MF Muller, JR Shainoff, KR Siebenlist, DL Amrani, GA Homandberg, J. Soria, C. Soria i M. Samama. "Studies on the ultrastructure of fibrin lacking fibrinopeptide B (beta- fibrin)". Blood 69, nr 4 (1.04.1987): 1073–81. http://dx.doi.org/10.1182/blood.v69.4.1073.bloodjournal6941073.

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Release of fibrinopeptide B from fibrinogen by copperhead venom procoagulant enzyme results in a form of fibrin (beta-fibrin) with weaker self-aggregation characteristics than the normal product (alpha beta-fibrin) produced by release of fibrinopeptides A (FPA) and B (FPB) by thrombin. We investigated the ultrastructure of these two types of fibrin as well as that of beta-fibrin prepared from fibrinogen Metz (A alpha 16 Arg----Cys), a homozygous dysfibrinogenemic mutant that does not release FPA. At 14 degrees C and physiologic solvent conditions (0.15 mol/L of NaCl, 0.015 mol/L of Tris buffer pH 7.4), the turbidity (350 nm) of rapidly polymerizing alpha beta-fibrin (thrombin 1 to 2 U/mL) plateaued in less than 6 min and formed a “coarse” matrix consisting of anastomosing fiber bundles (mean diameter 92 nm). More slowly polymerizing alpha beta-fibrin (thrombin 0.01 and 0.001 U/mL) surpassed this turbidity after greater than or equal to 60 minutes and concomitantly developed a network of thicker fiber bundles (mean diameters 118 and 186 nm, respectively). Such matrices also contained networks of highly branched, twisting, “fine” fibrils (fiber diameters 7 to 30 nm) that are usually characteristic of matrices formed at high ionic strength and pH. Slowly polymerizing beta-fibrin, like slowly polymerizing alpha beta-fibrin, displayed considerable quantities of fine matrix in addition to an underlying thick cable network (mean fiber diameter 135 nm), whereas rapidly polymerizing beta-fibrin monomer was comprised almost exclusively of wide, poorly anastomosed, striated cables (mean diameter 212 nm). Metz beta-fibrin clots were more fragile than those of normal beta-fibrin and were comprised almost entirely of a fine network. Metz fibrin could be induced, however, to form thick fiber bundles (mean diameter 76 nm) in the presence of albumin at a concentration (500 mumol/L) in the physiologic range and resembled a Metz plasma fibrin clot in that regard. The diminished capacity of Metz beta-fibrin to form thick fiber bundles may be due to impaired use or occupancy of a polymerization site exposed by FPB release. Our results indicate that twisting fibrils are an inherent structural feature of all forms of assembling fibrin, and suggest that mature beta-fibrin or alpha beta-fibrin clots develop from networks of thin fibrils that have the ability to coalesce to form thicker fiber bundles.

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Winklbauer, R., i C. Stoltz. "Fibronectin fibril growth in the extracellular matrix of the Xenopus embryo". Journal of Cell Science 108, nr 4 (1.04.1995): 1575–86. http://dx.doi.org/10.1242/jcs.108.4.1575.

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We show that the mechanism of fibronectin fibril formation on the blastocoel roof of the Xenopus embryo is comparable to that in other systems. Fibril assembly is inhibited by RGD peptide, by an amino-terminal fragment of fibronectin, and by cytochalasin B. When added exogenously, intact fibronectin, but not a 110 kDa cell binding fragment of fibronectin, is incorporated into fibrils. Thus, the blastocoel roof of Xenopus represents a valid model system for the study of fibronectin fibril formation in situ. Moreover, we show that fibril formation can be induced experimentally in this system. Examination of fibril elongation by double-labelling experiments reveals that individual, unbranched fibronectin fibrils grow only at one end, i.e. in a unipolar fashion. The rate of elongation is 4.7 microns/min. Most fibrils grow only for a short time, and the increase in total fibril length per cell is driven by the repeated initiation of new fibrils. Assembly of fibronectin into fibrils precedes cross-linking of fibronectin into multimers in this system.

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Gantioqui, Jorell, Ivan Stevic, Paul Y. Kim, Keith K. Lau, Anthony K. C. Chan i Howard H. W. Chan. "The Architecture Of Fibrin Clots Formed From Plasma With Low Platelet Levels Are Less Altered In The Presence Of Factor-Specific Anticoagulants Compared With Unfractionated Heparin". Blood 122, nr 21 (15.11.2013): 578. http://dx.doi.org/10.1182/blood.v122.21.578.578.

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Abstract Background Current guidelines for treating patients with thromboembolism and concomitant thrombocytopenia are based on anecdotal data and experts’ opinion. We previously described an in vitro assay using thromboelastography (TEG) to evaluate the effects of anticoagulants on plasma clot formation in the presence of autologous platelets. We showed that specific TEG clotting profiles for plasmas with predefined platelet counts in the presence of fondaparinux, rivaroxaban and dabigatran were less compromised compared with clots containing unfractionated heparin (UFH) and dalteparin. In this study, we further characterize the combined effects of anticoagulants and low platelet counts on the architecture of fibrin clots in plasma. Aim To determine the effect of various anticoagulants on the surface structure of fibrin clots in plasma when generated with autologous platelets at varying levels. Methods Scanning electron microscopy (SEM) was used to assess the surface structure of clots. Fresh human platelet-rich plasma and platelet-poor plasma (PPP) were obtained from the same donor and then the platelets were subsequently added back to PPP so that the final plasma samples contained predefined levels of platelets (PPP, 30,000, and 150,000 /mL). Each reaction mixture contained 30 µg/mL corn trypsin inhibitor, and one of the following anticoagulants: unfractionated heparin (UFH 0.3 IU/mL), dalteparin (1.0 IU/mL), fondaparinux (1.0 IU/mL), rivaroxaban (150 ng/mL) or dabigatran (180 ng/mL). For each condition, clotting was initiated with 10 mM CaCl2 and 1.2 pM tissue factor on a 0.02 µm Millipore membrane. After a 3-hr incubation, the clots were washed with phosphate buffered saline (pH 7.4), fixed with 2% v/v glutaraldehyde in 0.1 M phosphate buffer (pH 7.4), and then stained with 1% osmium tetroxide in 0.1 M sodium cacodylate buffer. The samples were dehydrated with gradient ethanol series, critical point dried, mounted onto stubs, and then gold sputter-coated for SEM examination at 20,000×. The porosity, fibril width and the number of fibrils were quantified for each clot generated. Results In the absence of anticoagulants, reducing the amount of platelets from 150,000 /mL to <10,000/mL in PPP had minimal effect on the porosity of clots, although there was a reduction in the number of fibrils by approximately 30% in the PPP sample (p < 0.05) and the fibrils were generally thicker (Fig. 1). Addition of anticoagulants to plasma containing 150,000/mL of platelets minimally changed the clot structure, except for UFH and dalteparin, which significantly increased the number of fibrils. Anticoagulants profoundly changed the clot structure as platelet levels fell below 150,000/ml. The greatest effects were observed for UFH, followed by dalteparin and then fondaparinux. The changes included an increase in porosity of clots (p < 0.05), a reduction in the number of fibrils (p < 0.05), and an increase in the width of fibril strands (p < 0.05). For the newer factor-specific anticoagulants, rivaroxaban changed the clot structure similar to fondaparinux in low platelets conditions, but dabigatran changed the clot structure less than rivaroxaban. Summary/Conclusion The present study supports our previous TEG observations that anticoagulants intensified the negative effects of low platelets during the formation of fibrin clots. This SEM study also demonstrates that anticoagulant therapy, in particular UFH or dalteparin, substantially changes the fibrin clot structure. This information provides evidence supporting the current clinical practice of withholding anticoagulants for patients with platelet count <30,000/mL. In addition, these in vitro data suggest that fondaparinux and the new factor-specific oral anticoagulants may be safer because clot structure is better preserved when compared to the traditional heparinoids. Yet, the absence of an antidote for these anticoagulants is a major hurdle in testing this hypothesis clinically because patients with severe thrombocytopenia inherit a high risk of bleeding. Disclosures: No relevant conflicts of interest to declare.

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Pradhan, Tejaswini, Karthikeyan Annamalai, Riddhiman Sarkar, Stefanie Huhn, Ute Hegenbart, Stefan Schönland, Marcus Fändrich i Bernd Reif. "Seeded fibrils of the germline variant of human λ-III immunoglobulin light chain FOR005 have a similar core as patient fibrils with reduced stability". Journal of Biological Chemistry 295, nr 52 (22.10.2020): 18474–84. http://dx.doi.org/10.1074/jbc.ra120.016006.

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Systemic antibody light chains (AL) amyloidosis is characterized by deposition of amyloid fibrils derived from a particular antibody light chain. Cardiac involvement is a major risk factor for mortality. Using MAS solid-state NMR, we studied the fibril structure of a recombinant light chain fragment corresponding to the fibril protein from patient FOR005, together with fibrils formed by protein sequence variants that are derived from the closest germline (GL) sequence. Both analyzed fibril structures were seeded with ex-vivo amyloid fibrils purified from the explanted heart of this patient. We find that residues 11-42 and 69-102 adopt β-sheet conformation in patient protein fibrils. We identify arginine-49 as a key residue that forms a salt bridge to aspartate-25 in the patient protein fibril structure. In the germline sequence, this residue is replaced by a glycine. Fibrils from the GL protein and from the patient protein harboring the single point mutation R49G can be both heterologously seeded using patient ex-vivo fibrils. Seeded R49G fibrils show an increased heterogeneity in the C-terminal residues 80-102, which is reflected by the disappearance of all resonances of these residues. By contrast, residues 11-42 and 69-77, which are visible in the MAS solid-state NMR spectra, show 13Cα chemical shifts that are highly like patient fibrils. The mutation R49G thus induces a conformational heterogeneity at the C terminus in the fibril state, whereas the overall fibril topology is retained. These findings imply that patient mutations in FOR005 can stabilize the fibril structure.

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Gabbay, D. M. "Fibred semantics and the weaving of logics. Part 1: Modal and intuitionistic logics". Journal of Symbolic Logic 61, nr 4 (grudzień 1996): 1057–120. http://dx.doi.org/10.2307/2275807.

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AbstractThis is Part 1 of a paper on fibred semantics and combination of logics. It aims to present a methodology for combining arbitrary logical systems Li, i ∈ I, to form a new system LI. The methodology ‘fibres’ the semantics i of Li into a semantics for LI, and ‘weaves’ the proof theory (axiomatics) of Li into a proof system of LI. There are various ways of doing this, we distinguish by different names such as ‘fibring’, ‘dovetailing’ etc, yielding different systems, denoted by etc. Once the logics are ‘weaved’, further ‘interaction’ axioms can be geometrically motivated and added, and then systematically studied. The methodology is general and is applied to modal and intuitionistic logics as well as to general algebraic logics. We obtain general results on bulk, in the sense that we develop standard combining techniques and refinements which can be applied to any family of initial logics to obtain further combined logics.The main results of this paper is a construction for combining arbitrary, (possibly not normal) modal or intermediate logics, each complete for a class of (not necessarily frame) Kripke models. We show transfer of recursive axiomatisability, decidability and finite model property.Some results on combining logics (normal modal extensions of K) have recently been introduced by Kracht and Wolter, Goranko and Passy and by Fine and Schurz as well as a multitude of special combined systems existing in the literature of the past 20–30 years. We hope our methodology will help organise the field systematically.

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Sandhya A, Gomathi Kanayiram, Kiruthika L i Aafreen Afroz S. "Nigella Sativa : A Potential Inhibitor for Insulin Fibril Formation". International Journal of Research in Pharmaceutical Sciences 11, nr 1 (23.01.2020): 765–74. http://dx.doi.org/10.26452/ijrps.v11i1.1891.

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The high order structure from proteins which are self-assembled are known as fibrils. They are collectively called as amyloid fibrils, which generally lead to neurodegenerative diseases like Alzheimer's, Parkinson's, Huntington's, Type II diabetes. Insulin fibril aggregation is identified to be the major cause of neurodegenerative diseases. The effect of Nigella sativa extract is analyzed based on the fibril inhibition process. The formed fibrils is reduced with the concentration increase of Nigella sativa extract. Insulin fibril is found in Type II diabetes patients after repeated insulin injections subcutaneously. Insulin fibrils are formed in organisms or humans irrespective of their places like hips, shoulder, hands and abdomen. These are evident from the anti-aggregation assay. Thioflavin T (ThT) fluroscence and congo red (CR) assay confirms the inhibition of insulin fibril in the presence of Nigella sativa (NS) extract. Further, inhibition of fibril was confirmed by Scanning Electron Microscope (SEM), where no insulin fibrils was detected whose secondary conformational changes are studied using Fourier Transform Infrared spectroscopy (FT-IR). It is confirmed that insulin fibril inhibition depends on the various concentration of Nigella sativa. Based on the results obtained, it is demonstrated that Nigella sativa extract inhibits the fibril formation and it also provides a therapeutic strategy to prevent insulin fibril formation.

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Morris, Timothy A., James J. Marsh, Roberto Fagnani, Michael Hagan i Kenneth M. Moser. "Degree of Polymer Organization Decreases the Binding of a Monoclonal Antibody Raised against the β-Chain Amino Terminus of Fibrin". Thrombosis and Haemostasis 77, nr 04 (1997): 704–9. http://dx.doi.org/10.1055/s-0038-1656038.

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SummaryAccurate non-invasive diagnosis of deep venous thrombosis and pulmonary embolism remains an elusive goal. Radiolabeled antibodies specific for the epitope exposed on the β-chain of fibrin after fibrino- peptide B release (anti-β) enabled in situ imaging of thrombi in experimental subjects with nuclear medicine techniques. When used in patients anticoagulated for thrombo-embolic disease, however, the antibody was unable to reliably image the thrombi. We postulated that the neoepitope on the β-chain of fibrin is covered up as fibrin organizes into a polymer network and is therefore exposed to the antibody only during active incorporation of fibrin subunits. We determined the equilibrium binding kinetics of an anti-β monoclonal antibody to fibrin in various stages of organization. The concentration of exposed epitopes on immobilized fibrin monomers was equal to the molar concentration of fibrin β-chains. The percentage of β-chains exposed to the antibodies markedly decreased as the fibrin network was allowed to organize, a process catalyzed by calcium. Conclusions: The β-chain amino terminus of fibrin is exposed transiently as subunits are added to the enlarging fibrin network. Anti-β antibodies bind preferentially to actively enlarging fibrin polymers.

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