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https://www.readbyqxmd.com/read/28917888/structure-of-cellulose-microfibrils-in-mature-cotton-fibres
#1
Marta Martínez-Sanz, Filomena Pettolino, Bernadine Flanagan, Michael J Gidley, Elliot P Gilbert
The structure of cellulose microfibrils in mature cotton fibres from three varieties - Gossypium hirsutum, G. barbadense and G. arboreum - has been investigated by a multi-technique approach combining small angle scattering techniques with spectroscopy and diffraction. Cellulose microfibrils present a Iβ-rich crystalline structure with limited surface disorder. Small angle scattering (SAXS and SANS) data have been successfully fitted using a core-shell model and the results obtained indicate that the cellulose microfibrils, formed by the association of 2-3 elementary fibrils, are composed of a ca...
November 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28917842/multi-scale-simulations-of-biological-systems-using-the-opep-coarse-grained-model
#2
Fabio Sterpone, Sébastien Doutreligne, Thanh Thuy Tran, Simone Melchionna, Marc Baaden, Phuong H Nguyen, Philippe Derreumaux
Biomolecules are complex machines that are optimized by evolution to properly fulfill or contribute to a variety of biochemical tasks in the cellular environment. Computer simulations based on quantum mechanics and atomistic force fields have been proven to be a powerful microscope for obtaining valuable insights into many biological, physical, and chemical processes. Many interesting phenomena involve, however, a time scale and a number of degrees of freedom, notably if crowding is considered, that cannot be explored at an atomistic resolution...
September 13, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28917837/memantine-inhibits-%C3%AE-amyloid-aggregation-and-disassembles-preformed-%C3%AE-amyloid-aggregates
#3
Kaori Ito, Mitsuhiro Makino, Keiko Okado, Taisuke Tomita
Memantine, an uncompetitive glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonist, is widely used as a medication for the treatment of Alzheimer's disease (AD). We previously reported that chronic treatment of AD with memantine reduces the amount of insoluble β-amyloid (Aβ) and soluble Aβ oligomers in animal models of AD. The mechanisms by which memantine reduces Aβ levels in the brain were evaluated by determining the effect of memantine on Aβ aggregation using thioflavin T and transmission electron microscopy...
September 13, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28917147/combined-in-silico-approaches-for-the-identification-of-novel-inhibitors-of-human-islet-amyloid-polypeptide-hiapp-fibrillation
#4
Palak Patel, Krupali Parmar, Vivek K Vyas, Dhaval Patel, Mili Das
Human islet amyloid polypeptide (hIAPP) is a natively unfolded polypeptide hormone of glucose metabolism, which is co-secreted with insulin by the β-cells of the pancreas. In patients with type 2 diabetes, IAPP forms amyloid fibrils because of diabetes-associated β-cells dysfunction and increasing fibrillation, in turn, lead to failure of secretory function of β-cells. This provides a target for the discovery of small organic molecules against protein aggregation diseases. However, the binding mechanism of these molecules with monomers, oligomers and fibrils to inhibit fibrillation is still an open question...
September 6, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28916413/emerging-structural-understanding-of-amyloid-fibrils-by-solid-state-nmr
#5
REVIEW
Beat H Meier, Roland Riek, Anja Böckmann
Amyloid structures at atomic resolution have remained elusive mainly because of their extensive polymorphism and because their polymeric properties have hampered structural studies by classical approaches. Progress in sample preparation, as well as solid-state NMR methods, recently enabled the determination of high-resolution 3D structures of fibrils such as the amyloid-β fibril, which is involved in Alzheimer's disease. Notably, the simultaneous but independent structure determination of Aβ1-42, a peptide that forms fibrillar deposits in the brain of Alzheimer patients, by two independent laboratories, which yielded virtually identical results, has highlighted how structures can be obtained that allow further functional investigation...
September 12, 2017: Trends in Biochemical Sciences
https://www.readbyqxmd.com/read/28916410/kinetic-stability-and-sequence-structure-studies-of-urine-derived-bence-jones-proteins-from-multiple-myeloma-and-light-chain-amyloidosis-patients
#6
Luis M Blancas-Mejía, Emily B Martin, Angela Williams, Jonathan S Wall, Marina Ramirez-Alvarado
It is now accepted that the ability of a protein to form amyloid fibrils could be associated both kinetic and thermodynamic protein folding parameters. A recent study from our laboratory using recombinant full-length (encompassing the variable and constant domain) immunoglobulin light chains found a strong kinetic control of the protein unfolding for these proteins. In this study, we are extending our analysis by using urine-derived Bence Jones proteins (BJPs) from five patients with light chain (AL) amyloidosis and four patients with multiple myeloma (MM)...
September 1, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28915764/sequence-dependent-aggregation-of-peptides-and-fibril-formation
#7
Nguyen Ba Hung, Duy-Manh Le, Trinh X Hoang
Deciphering the links between amino acid sequence and amyloid fibril formation is key for understanding protein misfolding diseases. Here we use Monte Carlo simulations to study the aggregation of short peptides in a coarse-grained model with hydrophobic-polar (HP) amino acid sequences and correlated side chain orientations for hydrophobic contacts. A significant heterogeneity is observed in the aggregate structures and in the thermodynamics of aggregation for systems of different HP sequences and different numbers of peptides...
September 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28915104/rift-valley-fever-phlebovirus-nss-protein-core-domain-structure-suggests-molecular-basis-for-nuclear-filaments
#8
Michal Barski, Benjamin Brennan, Ona K Miller, Jane A Potter, Swetha Vijayakrishnan, David Bhella, James H Naismith, Richard M Elliott, Ulrich Schwarz-Linek
Rift Valley fever phlebovirus (RVFV) is a clinically and economically important pathogen increasingly likely to cause widespread epidemics. RVFV virulence depends on the interferon antagonist non-structural protein (NSs), which remains poorly characterized. We identified a stable core domain of RVFV NSs (residues 83-248), and solved its crystal structure, a novel all-helical fold organized into highly ordered fibrils. A hallmark of RVFV pathology is NSs filament formation in infected cell nuclei. Recombinant virus encoding the NSs core domain induced intranuclear filaments, suggesting it contains all essential determinants for nuclear translocation and filament formation...
September 15, 2017: ELife
https://www.readbyqxmd.com/read/28913725/exercise-and-competitive-sport-physiology-adaptations-and-uncertain-long-term-risks
#9
REVIEW
Patrick T Gleason, Jonathan H Kim
The benefits of regular and moderate exercise training on cardiovascular outcomes have been well established. In addition, strenuous exercise training leads to corollary cardiac structural and functional adaptations that are sport-specific and facilitate athletic performance. In this review, the normal physiologic and hemodynamic changes that occur during exercise and the subsequent differential exercise-induced cardiac remodeling patterns that develop will be discussed. Paradoxically, recent data have raised concern about the long-term impact of higher doses of physical activity and exercise on mortality and cardiovascular health outcomes...
September 14, 2017: Current Treatment Options in Cardiovascular Medicine
https://www.readbyqxmd.com/read/28911806/comparison-of-characteristics-and-fibril-forming-ability-of-skin-collagen-from-barramundi-lates-calcarifer-and-tilapia-oreochromis-niloticus
#10
Wei Liao, Xia Guanghua, Yongcheng Li, Xuan Ri Shen, Chuan Li
The present study isolated and characterized the barramundi (Lates calcarifer) skin collagen (BC) and tilapia (Oreochromis niloticus) skin collagen (TC). The yields of BC and TC by enzymatic extraction were 47.3±3.7% and 52.6±6.1% respectively, dry weight. The SDS-PAGE profile indicated both collagens were mainly type I with two different α chains. FTIR spectra and X-ray diffraction confirmed that the triple helical structure of both collagens was not affected by pepsin digestion. The denaturation (Td) and melting temperature (Tm) were 36...
September 11, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28910420/role-of-the-central-lysine-cluster-and-scrapie-templating-in-the-transmissibility-of-synthetic-prion-protein-aggregates
#11
Bradley R Groveman, Gregory J Raymond, Katrina J Campbell, Brent Race, Lynne D Raymond, Andrew G Hughson, Christina D Orrú, Allison Kraus, Katie Phillips, Byron Caughey
Mammalian prion structures and replication mechanisms are poorly understood. Most synthetic recombinant prion protein (rPrP) amyloids prepared without cofactors are non-infectious or much less infectious than bona fide tissue-derived PrPSc. This effect has been associated with differences in folding of the aggregates, manifested in part by reduced solvent exclusion and protease-resistance in rPrP amyloids, especially within residues ~90-160. Substitution of 4 lysines within residues 101-110 of rPrP (central lysine cluster) with alanines (K4A) or asparagines (K4N) allows formation of aggregates with extended proteinase K (PK) resistant cores reminiscent of PrPSc, particularly when seeded with PrPSc...
September 14, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28910107/perturbation-of-the-f19-l34-contact-in-amyloid-ss-1-40-fibrils-induces-only-local-structural-changes-but-abolishes-cytotoxicity
#12
Felix Hoffmann, Juliane Adler, Bappaditya Chandra, Kaustubh R Mote, Gül Bekcioglu-Neff, Daniel Sebastiani, Daniel Huster
We explored structural details of fibrils formed by a mutated amyloid β (Aβ(1-40) peptide carrying a Phe19 to Lys19 mutation, which was shown to completely abolish the toxicity of the molecule. Computer models suggest that the positively charged Lys19 side-chain is expelled from the hydrophobic fibril interior upon fibrillation. This can be accommodated by either a 180° flip of the entire lower β-strand (model M1) or local perturbations of the secondary structure in the direct vicinity of the mutated site (model M2)...
September 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28906150/safety-and-efficacy-of-a-ttr-specific-antisense-oligonucleotide-in-patients-with-transthyretin-amyloid-cardiomyopathy
#13
Merrill D Benson, Noel R Dasgupta, Stacy M Rissing, Jessica Smith, Harvey Feigenbaum
OBJECTIVES: Cardiomyopathy is a major cause of death in both the hereditary form of transthyretin (TTR) amyloidosis and the sporadic late-age-onset transthyretin amyloidosis (ATTR wild-type (ATTRwt)). Clinically disease progression from time of diagnosis to death is usually quoted as 5- to 15-years. In prior studies, significant progression of cardiac parameters in patients with moderate to severe cardiomyopathy has been noted within a 12-month time span. METHODS: The present study was designed to prospectively monitor changes in cardiac parameters, both structural and functional, in patients with ATTR cardiomyopathy while treated with a TTR specific antisense oligonucleotide (ASO; IONIS-TTR℞) designed to lower blood levels of the amyloid fibril precursor protein...
September 14, 2017: Amyloid: the International Journal of Experimental and Clinical Investigation
https://www.readbyqxmd.com/read/28904878/the-effects-of-different-physical-activities-on-atrial-fibrillation-in-patients-with-hypertension-and-chronic-kidney-disease
#14
Márcio Galindo Kiuchi, Shaojie Chen, Neil Alexander Hoye
BACKGROUND: Atrial fibrillation (AF) is highly common, and is most frequently observed in individuals with hypertension and structural cardiac disease. Sympathetic hyperactivity plays a fundamental role in the progression, maintenance and aggravation of arrhythmia. Endurance exercise training clearly lowers sympathetic activity in sympathoexcitatory disease states, and is well-tolerated by patients with chronic kidney disease (CKD). METHODS: We assessed 50 CKD patients with hypertension...
September 2017: Kidney Research and Clinical Practice
https://www.readbyqxmd.com/read/28904308/aging-modulates-the-substrate-and-triggers-remodeling-in-atrial-fibrillation
#15
Yung-Kuo Lin, Yi-Ann Chen, Ting-I Lee, Yao-Chang Chen, Shih-Ann Chen, Yi-Jen Chen
Aging plays a critical role in the genesis of atrial fibrillation (AF) and also increases the risks of cardiac dysfunction and stroke in AF patients. AF is caused by increased AF triggering from abnormalities of the thoracic vein and/or modulated substrate (atrial) with enhancement of AF maintenance. Clinical and laboratory evidence indicates that aging is significant in the creation of atrial electrical and structural remodeling that leads to increased susceptibility to AF occurrence. Aging is commonly associated with cardiovascular comorbidities, oxidative stress, calcium dysregulation, atrial myopathy with apoptosis, and fibrosis, which all contribute to the genesis of AF...
September 14, 2017: Circulation Journal: Official Journal of the Japanese Circulation Society
https://www.readbyqxmd.com/read/28901573/validation-of-a-novel-cartoseg%C3%A2-segmentation-module-software-for-contrast-enhanced-computed-tomography-guided-radiofrequency-ablation-in-patients-with-atrial-fibrillation
#16
EDITORIAL
Hasan Imanli, Shaun Bhatty, Jean Jeudy, Yousra Ghzally, Kiddy Ume, Rama Vunnam, Refael Itah, Mati Amit, John Duell, Vincent See, Stephen Shorofsky, Timm M Dickfeld
INTRODUCTION: Visualization of left atrial (LA) anatomy using image integration modules has been associated with decreased radiation exposure and improved procedural outcome when used for guidance of pulmonary vein isolation (PVI) in atrial fibrillation (AF) ablation. We evaluated the CARTOSEG™ CT Segmentation Module (Biosense Webster, Inc.) that offers a new CT-specific semi-automatic reconstruction of the atrial endocardium. METHODS: The CARTOSEG™ CT Segmentation Module software was assessed prospectively in 80 patients undergoing AF ablation...
September 13, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28900287/quantitative-characterization-of-structural-and-mechanical-properties-of-boron-nitride-nanotubes-in-high-temperature-environments
#17
Xiaoming Chen, Christopher M Dmuchowski, Cheol Park, Catharine C Fay, Changhong Ke
The structural stability and mechanical integrity of boron nitride nanotubes (BNNTs) in high temperature environments are of importance in pursuit of their applications that are involved with extreme thermal processing and/or working conditions, but remain not well understood. In this paper, we perform an extensive study of the impacts of high temperature exposure on the structural and mechanical properties of BNNTs with a full structural size spectrum from nano- to micro- to macro-scale by using a variety of in situ and ex situ material characterization techniques...
September 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28898537/stabilizing-an-amyloidogenic-%C3%AE-6-light-chain-variable-domain
#18
Oscar D Luna-Martínez, Alejandra Hernández-Santoyo, Myriam I Villalba-Velázquez, Rosalba Sánchez-Alcalá, D Alejandro Fernández-Velasco, Baltazar Becerril
Light chain amyloidosis is a lethal disease where vital organs are damaged by the fibrillar aggregation of monoclonal light chains. λ6a is an immunoglobulin light chain encoded by the germ line gene segment implicated in this disease. AR is a patient-derived germ line variant with a markedly low thermodynamic stability and prone to form fibrils in vitro in less than an hour. Here, we sought to stabilize this domain by mutating some residues back to the germ line sequence, and the most stabilizing mutations were the single mutant AR-F21I and the double mutant AR-F21/IV104L, both located in the hydrophobic core...
September 12, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28898453/echocardiographic-guidance-and-monitoring-of-left-atrial-appendage-closure-with-atriclip-during-open-chest-cardiac-surgery
#19
Rachele Contri, Sara Clivio, Tiziano Torre, Tiziano Cassina
Left atrial appendage (LAA) closure prevents thromboembolic risk and avoids lifelong anticoagulation due to atrial fibrillation (AF). Nowadays, AtriClip, a modern epicardial device approved in June 2010, allows external and safe closure of LAA in patients undergoing cardiac surgery during other open-chest cardiac surgical procedures. Such a surgical approach and its epicardial deployment differentiates LAA closure with AtriClip from percutaneous closure techniques such as Watchman (Boston Scientific, Marlborough, MA, USA), Lariat (SentreHEART Inc...
September 12, 2017: Echocardiography
https://www.readbyqxmd.com/read/28898051/effect-of-alzheimer-familial-chromosomal-mutations-on-the-amyloid-fibril-interaction-with-different-pet-tracers-insight-from-molecular-modeling-studies
#20
Kanagasabai Balamurugan, Natarajan Arul Murugan, Bengt Långström, Agneta Nordberg, Hans Ågren
Alzheimer's disease (AD) is the most common neurodegenerative disorder. Along with an increasing number of elderly worldwide it poses a great challenge for the society and healthcare. Although sporadic AD is the common form of AD, 2-3% of the AD cases are expected to be due to mutations in the beta region of the amyloid precursor protein which is referred to as autosomal dominant AD (ADAD). These mutations may cause changes in the secondary structure of the amyloid beta fibrils and may alter the fibrillization rate leading to changes in the disease development and could also affect the binding to tracers used in diagnosis...
September 12, 2017: ACS Chemical Neuroscience
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