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https://www.readbyqxmd.com/read/29211680/the-impact-of-water-on-the-ambivalent-behavior-and-paradoxical-phenomenon-of-the-amyloid-%C3%AE-fibril-protein
#1
Tamás Vajda, András Perczel
The crucial role of water in amyloid-β(Aβ) fibril proteins is evaluated in several ways including the water's thermodynamic and kinetic solvation effects. As regards the water's character, its hindered-rotation barriers are also considered. The following protein molecules considered here are: the Aβ40 (PDB ID: 2LMN), Aβ42 (PDB ID: 5KK3 and 2NAO) and the double-layered Aβ17-42 fibril. We discuss: (i) extracellular Aβ40 and Aβ42 fibril monomers exhibit an ambivalent propensity to transform into a helical form toward the N-term region and a β-strand-like form near the C-terminal; (ii) interfacial water molecules play a crucial role in protein-protein interactions, as molecular dynamics simulations have shown a significant impact on the protein-protein binding; (iii) it is shown that the spontaneous dimerization process of the Aβ42 fibril protein in water occurs via a two-step nucleation-accommodation mechanism; (iv) MD simulations of the double-layered Aβ17-42 fibril model show that the C↔C interface appears more energetically favorable than the N↔N interface due to large hydrophobic contacts; (v) the water's role in the HET-s prion and in the Aβ fibrillar aggregates; (vi) it was found that the monomer-oligomer equilibrium spontaneously dissociates into stable monomeric species when they are incubated up to 3 μm for a longer time (>1 week) in a physiological buffer...
December 20, 2017: Biomolecular Concepts
https://www.readbyqxmd.com/read/29209068/-carboranyl-cysteine-synthesis-structure-and-self-assembly-behavior-of-a-novel-%C3%AE-amino-acid
#2
Tianyu He, Jennifer C Misuraca, Rabi A Musah
Substitution of the thiol proton in cysteine with m-carborane furnished 2-amino-3-(1,7-dicarba-closo-dodecacarboranyl-1-thio)propanoic acid (3), a boron cluster amino acid that exhibits self-assembly to form micron-sized constructs. Field emission scanning electron microscopy revealed that ethanol solutions of 3 form floret-shaped constructs, while fibrillar architectures are formed in water. Furthermore, slow evaporation of methanol solutions of 3 produced crystals whose structure was revealed by X-ray crystallography...
December 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29208553/fibril-growth-kinetics-link-buffer-conditions-and-topology-of-3d-collagen-i-networks
#3
Liv Kalbitzer, Tilo Pompe
Three-dimensional fibrillar networks reconstituted from collagen I are widely used as biomimetic scaffolds for in vitro and in vivo cell studies. Various physicochemical parameters of buffer conditions for in vitro fibril formation are well known, including pH-value, ion concentrations and temperature. However, there is a lack of a detailed understanding of reconstituting well-defined 3D network topologies, which is required to mimic specific properties of the native extracellular matrix. We screened a wide range of relevant physicochemical buffer conditions and characterized the topology of the reconstituted 3D networks in terms of mean pore size and fibril diameter...
December 2, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/29206067/oligomeric-and-fibrillar-amyloid-beta-42-induce-platelet-aggregation-partially-through-gpvi
#4
O Elaskalani, I Khan, M Morici, C Matthysen, M Sabale, R N Martins, G Verdile, P Metharom
The effects of the Alzheimer's disease (AD)-associated Amyloid-β (Aβ) peptides on platelet aggregation have been previously assessed, but most of these studies focused on Aβ40 species. It also remains to be determined which distinct forms of Aβ peptides exert differential effects on platelets. In AD, oligomeric Aβ42 species is widely thought to be a major contributor to the disease pathogenesis. We, therefore, examine the ability of oligomeric and fibrillary Aβ42 to affect platelet aggregation. We show that both forms of Aβ42 induced significant platelet aggregation and that it is a novel ligand for the platelet receptor GPVI...
December 5, 2017: Platelets
https://www.readbyqxmd.com/read/29205905/a-simple-modification-method-to-obtain-anisotropic-and-porous-3d-microfibrillar-scaffolds-for-surgical-and-biomedical-applications
#5
Vahid Hosseini, Olivera Evrova, Simon P Hoerstrup, Viola Vogel
In native tissues, cellular organization is predominantly anisotropic. Yet, it remains a challenge to engineer anisotropic scaffolds that promote anisotropic cellular organization at macroscopic length scales. To overcome this challenge, an innovative, cheap and easy method to align clinically approved non-woven surgical microfibrillar scaffolds is presented. The method involves a three-step process of coating, unidirectional stretching of scaffolds after heating them above glass transition temperature, and cooling back to room temperature...
December 4, 2017: Small
https://www.readbyqxmd.com/read/29204720/effect-of-mercury-on-pollen-germination-and-tube-growth-in-lilium-longiflorum
#6
Thomas Sawidis, Gülriz Baycu, Gül Cevahir-Öz, Elzbieta Weryszko-Chmielewska
Pollen development and germination were adversely affected by the presence of mercury, whereas low-concentrations stimulated the whole procedure. Mercury caused morphological anomalies during the tube growth, characterized by irregularly increasing diameters and swelling tips. The main effect was the anomalous cell wall formation at the tip where a substantial number of organelles were found reducing the secretory vesicles. The dense organelle concentration caused a significant reduction of cytoplasmic movement integrity, and the cytosol streaming was gradually reduced or stopped completely...
December 4, 2017: Protoplasma
https://www.readbyqxmd.com/read/29197951/epibiont-growth-on-filamentous-bacteria-found-in-activated-sludge-a-morphological-approach
#7
Thobela Conco, Sheena Kumari, Thor Stenström, Faizal Bux
Occurrence of epibiont attachment on filamentous bacteria is a common phenomenon in activated sludge. In this study, an attempt has been made to elucidate the intrinsic nature of the attachment between the epibionts and filamentous bacteria based on microscopic observations. Characterization of the epiflora based on fluorescence in situ hybridization using group level probes revealed that the epibionts colonizing these filamentous bacteria largely belongs to the class Alphaproteobacteria, followed by Beta and Gammaproteobacteria...
December 2, 2017: Archives of Microbiology
https://www.readbyqxmd.com/read/29196815/amyloid-%C3%AE-oligomers-a%C3%AE-os-in-alzheimer-s-disease
#8
REVIEW
Barbara Mroczko, Magdalena Groblewska, Ala Litman-Zawadzka, Johannes Kornhuber, Piotr Lewczuk
The causative role of amyloid β 1-42 (Aβ42) aggregation in the pathogenesis of Alzheimer's disease (AD) has been under debate for over 25 years. Primarily, scientific efforts have focused on the dyshomeostasis between production and clearance of Aβ42. This imbalance may result from mutations either in genes for the substrate, i.e., amyloid precursor protein or in genes encoding presenilin, the enzyme of the reaction that generates Aβ42. Currently, it is supposed that soluble oligomers of amyloid beta (AβOs) and not fibrillar Aβ42 within neuritic plaques may be the toxic factors acting on a very early stage of AD, perhaps even initiating pathological cascade...
December 1, 2017: Journal of Neural Transmission
https://www.readbyqxmd.com/read/29196165/osteopontin-promotes-collagen-i-synthesis-in-hepatic-stellate-cells-by-mirna-129-5p-inhibition
#9
Yinghua Chen, Yitao Ou, Jiale Dong, Guizhi Yang, Zhi Zeng, Ying Liu, Bing Liu, Weidong Li, Xiaoshun He, Tian Lan
Activation of hepatic stellate cells (HSCs) is an essential event in the initiation and progression of liver fibrosis. HSCs are believed to be the major source of collagen-producing myofibroblasts in fibrotic livers. A key feature in the pathogenesis of liver fibrosis is fibrillar Collagen I (Col 1) deposition. Osteopontin (OPN), an extracellular matrix (ECM) cytokine expressed in HSCs, could drive fibrogenesis by modulating the HSC pro-fibrogenic phenotype and Col 1 expression. Here, we aimed to investigate the molecular mechanism of OPN regulating the activation of HSCs...
November 28, 2017: Experimental Cell Research
https://www.readbyqxmd.com/read/29196110/degradation-of-tropoelastin-and-skin-elastin-by-neprilysin
#10
Angela C Mora Huertas, Christian E H Schmelzer, Chiara Luise, Wolfgang Sippl, Markus Pietzsch, Wolfgang Hoehenwarter, Andrea Heinz
Neprilysin is also known as skin fibroblast-derived elastase, and its up-regulation during aging is associated with impairments of the elastic fiber network, loss of skin elasticity and wrinkle formation. However, information on its elastase activity is still limited. The aim of this study was to investigate the degradation of fibrillar skin elastin by neprilysin and the influence of the donor's age on the degradation process using mass spectrometry and bioinformatics approaches. The results showed that cleavage by neprilysin is dependent on previous damage of elastin...
November 28, 2017: Biochimie
https://www.readbyqxmd.com/read/29190794/3d-collagen-fibrillar-microstructure-guides-pancreatic-cancer-cell-phenotype-and-serves-as-a-critical-design-parameter-for-phenotypic-models-of-emt
#11
T J Puls, Xiaohong Tan, Catherine F Whittington, Sherry L Voytik-Harbin
Pancreatic cancer, one of the deadliest cancers, is characterized by high rates of metastasis and intense desmoplasia, both of which are associated with changes in fibrillar type I collagen composition and microstructure. Epithelial to mesenchymal transition (EMT), a critical step of metastasis, also involves a change in extracellular matrix (ECM) context as cells detach from basement membrane (BM) and engage interstitial matrix (IM). The objective of this work was to develop and apply an in-vitro three-dimensional (3D) tumor-ECM model to define how ECM composition and biophysical properties modulate pancreatic cancer EMT...
2017: PloS One
https://www.readbyqxmd.com/read/29190286/nucleolar-sub-compartments-in-motion-during-rrna-synthesis-inhibition-contraction-of-nucleolar-condensed-chromatin-and-gathering-of-fibrillar-centers-are-concomitant
#12
Pavel Tchelidze, Aassif Benassarou, Hervé Kaplan, Marie-Françoise O'Donohue, Laurent Lucas, Christine Terryn, Levan Rusishvili, Giorgi Mosidze, Nathalie Lalun, Dominique Ploton
The nucleolus produces the large polycistronic transcript (47S precursor) containing the 18S, 5.8S and 28S rRNA sequences and hosts most of the nuclear steps of pre-rRNA processing. Among numerous components it contains condensed chromatin and active rRNA genes which adopt a more accessible conformation. For this reason, it is a paradigm of chromosome territory organization. Active rRNA genes are clustered within several fibrillar centers (FCs), in which they are maintained in an open configuration by Upstream Binding Factor (UBF) molecules...
2017: PloS One
https://www.readbyqxmd.com/read/29186195/assemblies-of-amyloid-%C3%AE-30-36-hexamer-and-its-g33v-l34t-mutants-by-replica-exchange-molecular-dynamics-simulation
#13
Zhenyu Qian, Qingwen Zhang, Yu Liu, Peijie Chen
The aggregation of amyloid-β peptides is associated with the pathogenesis of Alzheimer's disease, in which the 30-36 fragments play an important part as a fiber-forming hydrophobic region. The fibrillar structure of Aβ30-36 has been detected by means of X-ray diffraction, but its oligomeric structural determination, biophysical characterization, and pathological mechanism remain elusive. In this study, we have investigated the structures of Aβ30-36 hexamer as well as its G33V and L34T mutants in explicit water environment using replica-exchange molecular dynamics (REMD) simulations...
2017: PloS One
https://www.readbyqxmd.com/read/29178626/supramolecular-chirality-issues-in-unorthodox-naphthalene-diimide-gelators
#14
Suhrit Ghosh, Goutam Ghosh, Mithun Paul, Tsuneaki Sakurai, Wakana Matsuda, Shu Seki
Self-assembly of a few 1,3-dihydroxyl functionalized naphthalene diimide (NDI) derivatives is reported with particular emphasis on the impact of chirality on gelation and effect of self-assembly on electrical conductivity. (R)-NDI, devoid of any alkyl chains, exhibits gelation in TCE by a ladder like H-bonded chain formation between the 1,3-dihydroxyl group leading to the fibrillar structures with preferential helicity. The (S)- isomer also exhibits identical gelation but produces fibrils with the opposite handedness...
November 27, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29178552/educational-and-practice-gaps-in-the-management-of-volar-melanocytic-lesions
#15
C M Costello, S Ghanavatian, M Temkit, M R Buras, D J DiCaudo, D L Swanson, A R Mangold
BACKGROUND: The benign and malignant patterns of acral melanocytic nevi (AMN) and acral melanomas (AM) have been defined in a series of retrospective studies. A 3-step algorithm was developed to determine when to biopsy acral melanocytic lesions. This algorithm has only been applied to a Japanese population. OBJECTIVES: Our study aimed to review the current management strategy of acral melanocytic lesions and to investigate the utility of the 3-step algorithm in a predominately Caucasian cohort...
November 24, 2017: Journal of the European Academy of Dermatology and Venereology: JEADV
https://www.readbyqxmd.com/read/29177933/modeling-the-effect-of-collagen-fibril-alignment-on-ligament-mechanical-behavior
#16
Christina J Stender, Evan Rust, Peter T Martin, Erica E Neumann, Raquel J Brown, Trevor J Lujan
Ligament mechanical behavior is primarily regulated by fibrous networks of type I collagen. Although these fibrous networks are typically highly aligned, healthy and injured ligament can also exhibit disorganized collagen architecture. The objective of this study was to determine whether variations in the collagen fibril network between neighboring ligaments can predict observed differences in mechanical behavior. Ligament specimens from two regions of bovine fetlock joints, which either exhibited highly aligned or disorganized collagen fibril networks, were mechanically tested in uniaxial tension...
November 24, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/29165324/in-vivo-evaluation-of-modified-silk-fibroin-scaffolds-with-a-mimicked-microenvironment-of-fibronectin-decellularized-pulp-tissue-for-maxillofacial-surgery
#17
Thanh H Thai, Thongchai Nuntanaranont, Suttatip Kamolmatyakul, Jirut Meesane
This study aimed to carry out in vivo testing of the formation of new bone by modified silk fibroin scaffolds with a mimicked microenvironment of fibronectin/decellularized pulp in bone defects. Silk fibroin scaffolds were fabricated into three-dimensional scaffolds before being coated with fibronectin/decellularized pulp. The coated scaffolds were implanted into rabbits. Twenty-four bicortical calvarial defects in 12 rabbits were divided randomly into two groups: non-coated and coated silk fibroin scaffolds...
November 22, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/29164186/phenylalanine-and-derivatives-as-versatile-low-molecular-weight-gelators-design-structure-and-tailored-function
#18
REVIEW
Tanmay Das, Marleen Häring, Debasish Haldar, David Díaz Díaz
Phenylalanine (Phe) is an essential amino acid classified as neutral and nonpolar due to the hydrophobic nature of the benzyl side chain. In the field of materials science, the chemical modification of phenylalanine at C or N terminus has enabled to synthesize a large number of low-molecular-weight gelators over the past decade. Thus, many physical (or supramolecular) softgel materials have been fabricated by self-assembly of Phe-derived building blocks, which can be programmed with atomic level information and modification...
November 22, 2017: Biomaterials Science
https://www.readbyqxmd.com/read/29163603/novel-ribonuclease-activity-differs-between-fibrillarins-from-arabidopsis-thaliana
#19
Ulises Rodriguez-Corona, Alejandro Pereira-Santana, Margarita Sobol, Luis C Rodriguez-Zapata, Pavel Hozak, Enrique Castano
Fibrillarin is one of the most important nucleolar proteins that have been shown as essential for life. Fibrillarin localizes primarily at the periphery between fibrillar center and dense fibrillar component as well as in Cajal bodies. In most plants there are at least two different genes for fibrillarin. In Arabidopsis thaliana both genes show high level of expression in transcriptionally active cells. Here, we focus on two important differences between A. thaliana fibrillarins. First and most relevant is the enzymatic activity by AtFib2...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/29162487/molecular-pathways-of-cell-mediated-degradation-of-fibrillar-collagen
#20
REVIEW
Sara Sprangers, Vincent Everts
Fibrillar collagens are the most abundant components of the extracellular matrix and provide stability to connective tissues, such as bone, cartilage and skin. An imbalance in collagen turnover inevitably affects the function of these tissues. Therefore, the molecular and cellular mechanisms involved in the synthesis and degradation of collagen have received increasing attention. This short review attempts to summarize our present understanding of how different pathways of collagen degradation are used by different cell types...
November 20, 2017: Matrix Biology: Journal of the International Society for Matrix Biology
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