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Role of lipids in virus assembly

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195824 Year: Pages: 91 DOI: 10.3389/978-2-88919-582-4 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology --- Botany
Added to DOAB on : 2016-03-10 08:14:32
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RNA enveloped viruses comprise several families belonging to plus and minus strand RNA viruses, such as retroviruses, flavoviruses and orthomyxoviruses. Viruses utilize cellular lipids during critical steps of replication like entry, assembly and egress. Growing evidence indicate important roles for lipids and lipid nanodomains in virus assembly. This special topic covers key aspects of virus-membrane interactions during assembly and egress, especially those of retroviruses and Ebola virus (EBOV). Virus assembly and release involve specific and nonspecific interactions between viral proteins and membrane compartments. Retroviral Gag proteins assemble predominantly on the PM. Despite the great progress in identifying the factors that modulate retroviral Gag assembly on the PM, there are still gaps in our understanding of precise mechanisms of Gag-membrane interactions. Studies over the last two decades have focused on the mechanisms by which other retroviral Gag proteins interact with membranes during assembly. These include human immunodeficiency virus (HIV), Rous sarcoma virus (RSV), equine infectious anemia virus (EIAV), Mason-Pfizer monkey virus (M-PMV), murine leukemia virus (MLV), and human T-lymphotropic virus type (HTLV-1). Additionally, assembly of filoviruses such as EBOV also occurs on the inner leaflet of the PM. The articles published under this special topic highlight the latest understanding of the role of membrane lipids during virus assembly, egress and release.

Keywords

retroviruses --- HIV 1 --- Gag --- Matrix --- membrane --- NMR --- Ebola --- VP40

Modelling the human cardiac fluid mechanics. 2nd ed

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ISBN: 3866440871 Year: Pages: 39 p. DOI: 10.5445/KSP/1000005151 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:01:58
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In the second edition of the article a virtual heart modelsimulating the flow in the active left human ventricle andatrium is presented. Because in vivo myocardium data is notavailable, the movement of the active ventricle and its atriumis given by three-dimensional, time-dependent invivo image dataof a nuclear spin MRI tomograph. The passive part of the virtualheart model consists of a model aorta and of two-dimensionallymodelled heart valves. As the flow is actively driven by theventricle and atrium, a coupling off low and structure isnecessary to take into account the deviation of the aorta andthe closing and opening of the heart valves. This coupling isreplaced by the movement given by MRI tomograph and ultrasonicDoppler echocardiography, since we focus on the flow simulationin the left pumping ventricle. The flow simulation is performedby a validated commercial software package that uses the finitevolume method. The flow resistance of the circulation throughthe body is taken into account with a simplified circulationmodel. The article shows how the virtual heart model can be usedto predict flow losses and flow structures due to pathologicalventricle contraction defects. It provides as an example theflow simulation of an unhealthy human ventricle with ananeurysm. The flow structure and flow losses are consideredbefore and after surgery.

Untersuchungen zur Struktur und zur Beladungskinetik von Tiefenfiltern

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ISBN: 3937300619 Year: Pages: XV, 195 p. DOI: 10.5445/KSP/1000003485 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: Chemical Engineering
Added to DOAB on : 2019-07-30 20:01:58
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Die Tiefenfiltration ist für all jene technischen Anwendungen ein klassisches Verfahren zur Abscheidung von Partikeln aus Fluiden, bei welchen die Partikeln nur in mäßiger Konzentration von einigen mg/m3 vorkommen oder der Druckverlust sehr gering sein soll (VDI 3677 Blatt 2). In dieser Arbeit werden Messmethoden und Modelle entwickelt, die zur zukünftigen Simulation der Filtrationskinetik von Faserfiltermedien benötigt werden.Zum einen ist es notwendig, a priori die lokale Packungsdichte in einer Filterprobe zu kennen, um spätere Simulationen und Experimente für dieselbe Probe überprüfen zu können. Dies wird mit der neu entwickelten und verifizierten Methode zur Bestimmung der lokalen Packungsdichte innerhalb einer Filterprobe, basierend auf der mit quantitativer MRI gemessenen Faserstruktur, nun möglich. Weiterhin wird die hierfür notwendige Auflösung bestimmt sowie der Einfluss der Anordnung der lokalen Packungsdichten als auch der Einfluss der Zellengröße auf die Vorhersage des Druckverlustes mittels des in der Filtertechnik üblichen Zellenmodells untersucht.Zum anderen ist ein detailliertes Verständnis der Mikrophänomene bei der Beladung einzelner Fasern notwendig, da sich die Filterperformance aufgrund der abgeschiedenen Partikeln ändert. Hierzu ist, wie die Literaturübersicht zeigt, noch wenig bekannt. Daher wurde das CFD Programm FLUENT durch User-Defined-Functions so erweitert, dass der Aufbau von Partikelstrukturen an einzelnen Fasern unter Berücksichtigung des Sperreffekts als auch des Einflusses der abgeschiedenen Partikeln auf die Strömung sowie durch Modellierung von Haften bzw. Abprallen erstmals wirklichkeitsnah durchgeführt werden kann. Es wird gezeigt, dass eine qualitativ gute Übereinstimmung der Partikelstruktur mit experimentellen Ergebnissen anderer Arbeiten erzielt wird. Die Möglichkeit der Simulation erlaubt es dann, gezielt den Einfluss der Partikelhaftung auf die Morphologie und mittleren Packungsdichte der Partikelstruktur sowie auf die Änderung von Abscheidegrad und Druckverlust mit zunehmender Anzahl abgeschiedener Partikeln zu untersuchen. In weiteren Simulationen wird für monodisperse Latex- und Kalksteinpartikeln bei kleineren Stokeszahlen ein vertieftes Verständnis der Filtrationskinetik an Einzelfasern gewonnen. In einem Ausblick wird abschließend die mögliche Anwendung der neuen Routinen zur Simulation des Clogging von Faserstrukturen aufgezeigt.

Transcellular Cycles Underlying Neurotransmission

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196548 Year: Pages: 105 DOI: 10.3389/978-2-88919-654-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2016-08-16 10:34:25
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Synaptic transmission demands the operation of a highly specialized metabolic machinery involving the transfer of metabolites and neurotransmitters between neurons, astrocytes and microvessels. In the last years, important advances have occurred in our understanding of the mechanisms underlying cerebral activation, neuroglial coupling and the associated neurovascular response. Briefly, exacerbated oxygen consumption in stimulated neurons is thought to trigger glycolytic lactate and glucose transfer from astrocytes which, in turn, obtain these fuels from the microvasculature. Neurotransmitter release is made possible by a combination of transcellular cycles exchanging metabolites between these three compartments, returning eventually the synapsis to its pre-firing situation in the resting periods. In spite of the enormous progresses achieved in recent years, the drivers determining the predominant direction of the fluxes, their quantitative contribution and their energy requirements, have remained until today incompletely understood, more particularly under the circumstances prevailing in vivo. In many instances, progress derived from the implementation of novel methodological approaches including advanced neuroimaging and neurospectroscopy methods. As a consequence, literature in the field became vast, diverse and spread within journals of different specialities. The e-book "Transcellular cycles underlying neurotransmission" aims to summaryze in a single volume, recent progress achieved in hypothesis, methods and interpretations on the trafficking of metabolites between neurons and glial cells, and the associated mechanisms of neurovascular coupling.

Glycan Diversity in Fungi, Bacteria and Sea Organisms

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199426 Year: Pages: 85 DOI: 10.3389/978-2-88919-942-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Internal medicine
Added to DOAB on : 2016-01-19 14:05:46
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The cell surface of fungi, bacteria and sea organisms is highly glycosylated. These glycans are oligo- or polysaccharide molecules that can be secreted or attached to protein or lipids forming glycoconjugates. They present extraordinary structural diversity that could explain their involvement in many fundamental cellular processes, including growth, differentiation and morphogenesis. Considerable advances have been made on the structural elucidation of these glycans. Their primary structures were determined based on a combination of mass spectrometry and NMR spectroscopy techniques. The combination of these sensitive and powerful techniques has allowed us to increase our structural knowledge of a wide variety of glycans expressed by different fungi, bacteria and sea organisms.

Special Issue Dedicated to Late Professor Takuo Okuda. Tannins and Related Polyphenols Revisited: Chemistry, Biochemistry and Biological Activities

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ISBN: 9783038978343 / 9783038978350 Year: Pages: 316 DOI: 10.3390/books978-3-03897-835-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Medicine (General)
Added to DOAB on : 2019-06-26 10:09:00
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Antioxidative polyphenols represented by tannins and flavonoids are rich in numerous food sources and traditional natural medicines and currently attracting increased attention in health care and food industries because of their multiple biological activities that are favorable to human health. Commemorating the outstanding achievements on tannins by Dr. Takuo Okuda on the occasion of his passing away in December 2016, his colleagues, friends, and worldwide experts of polyphenol research have contributed 18 papers on their recent study to the Special Issue of Molecules. This book is its reprinted form. This covers reviews of structural features, historical usages, and biological activities of unique class of ellagitannins and condensed tannins, and original articles on the most up-to-date findings on the anticancer effect of green tea catechins, the antivirus effect of tannins comparing with the clinically used drugs, the analytical method of ellagitannins using quantitative NMR, the chemical structures of Hydrangea-blue complex (pigment) and condensed tannins in Ephedra sinica and purple prairie clover, and the relationship of condensed tannins in legumes and grape-marc with methane production in the in vitro ruminant system, and others. This book will be useful to natural product chemists and also to researchers in pharmaceutical and/or food industry.

Keywords

Dittrichia viscosa --- antifungal activities --- Candida spp. --- Malassezia spp. --- Microsporum canis --- Aspergillus fumigates --- Ephedra sinica --- proanthocyanidin --- oligomer --- thiolysis --- phloroglucinolysis --- TDDFT --- ECD --- neuraminidase --- inhibition --- tannins --- oseltamivir carboxylate --- zanamivir --- crystal structure --- molecular interactions --- oenothein B --- ellagitannin --- macrocyclic oligomer --- Onagraceae --- Myrtaceae --- Lythraceae --- antioxidants --- antitumor effect --- immunomodulatory effect --- anti-inflammation --- tannin composition --- purple prairie clover --- conservation method --- protein precipitation --- Escherichia coli --- Cynanchum wilfordii --- phenolic glycoside --- 2-O-?-laminaribiosyl-4-hydroxyacetophenone --- cynandione A --- thin layer chromatography --- Cynanchum auriculatum --- Acacia mearnsii bark --- wattle tannin --- proanthocyanidins --- biological activities --- tannins --- vegetable tanning --- European historic leathers --- colorimetric tests --- spectroscopy --- UV-Vis --- FTIR --- triple-negative breast cancer --- fatty acid synthase --- FASN inhibition --- polyphenolic FASN inhibitors --- (?)-epigallocatechin 3-gallate --- synthetic analogues --- apoptosis --- anticancer activity --- 1H-NMR --- quantitative NMR --- ellagitannin --- Geranium thunbergii --- geraniin --- Aluminum ion --- blue color development --- 5-O-caffeoylquinic acid --- 3-O-glucosyldelphinidin --- Hydrangea macrophylla --- ESI-mass --- metal complex --- Coreopsis lanceolata L. --- chalcone --- flavanone --- flavonol --- aurone --- Horner–Wadsworth–Emmons reaction --- condensed tannin --- bioactivity --- methanogenesis --- grape marc --- fatty acids --- in vitro batch fermentation --- neuroprotection --- PC12 --- NGF --- differentiation --- amyloid-? peptide --- taxanes --- hormesis --- polyphenol --- bamboo leaf extract --- overlay method --- ellagitannin --- structure --- revision --- (?)-epigallocatechin gallate --- immune checkpoint --- interferon-? --- epidermal growth factor --- lung tumor --- proanthocyanidins --- condensed tannins --- thiolysis --- NMR spectroscopy --- ultrahigh-resolution negative mode MALDI-TOF mass spectrometry --- antioxidant --- ORAC assay --- Acacia --- forage legume --- Trapa taiwanensis Nakai --- hydrolysable tannin --- stability --- gallotannin --- ellagitannin

Looking Forward to the Future of Heparin: New Sources, Developments and Applications

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ISBN: 9783038429494 / 9783038429500 Year: Pages: 282 DOI: 10.3390/books978-3-03842-950-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-08-28 11:21:28
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This book is a printed edition of the Special Issue Looking Forward to the Future of Heparin: New Sources, Developments and Applications that was published in Molecules

Keywords

thrombin inhibition --- LMWH --- antithrombin --- heparin oligosaccharides --- ternary complex --- heparin --- hepcidin --- iron homeostasis --- anemia --- heparin-induced thrombocytopenia --- diagnosis --- functional assay --- platelets --- heparin --- heparan sulphate --- TGF-? --- bone morphogenetic protein (BMP) --- growth and differentiation factor (GDF) --- GDNF --- BMP antagonists --- noggin --- sclerostin --- gremlin --- heparin --- enoxaparin --- subarachnoid hemorrhage --- edema --- brain injury --- inflammation --- cisplatin --- low molecular weight heparin (LMWH) --- ovarian cancer --- resistance --- heparin --- glycosaminoglycans --- chondroitin sulfate --- perylene diimide dyes --- dermatan sulfate --- fluorescent probe --- Heparin Red --- assay --- dermatan sulfate --- human plasma --- heparin --- alginate --- sulfated alginate --- biomaterials --- heparin --- heparan sulfate --- serglycin --- proteoglycan --- recombinant expression --- bioreactor --- theranostics --- solid lipid nanoparticles --- iron oxide nanoparticles --- heparin coating --- intestinal lymphatic absorption --- heparin --- heparin process --- manufacturing methods --- industrial --- super paramagnetic iron oxide nanoparticles (SPION) --- hyaluronic acid (HA) --- bovine serum albumin (BSA) --- Fe3O4·DA-BSA/HA --- paclitaxel (PTX) --- magnetic resonance imaging (MRI) --- low-molecular-weight heparin --- dalteparin --- NMR --- LC-MS --- affinity chromatography --- danaparoid sodium --- low molecular weight glycosaminoglycans --- orthogonal multi-analytical methods --- sequence and compositional investigations --- component quantitative analysis --- heparin --- crude heparin --- NMR --- quantitative NMR --- PCA --- chemometric --- HSQC --- bovine heparin --- porcine heparin --- molecular weight --- size exclusion chromatography --- pharmacopeia --- Fondaparinux sodium --- extended physicochemical characterization --- qNMR --- single crystal X-ray structure --- reference standard --- iduronic acid conformation --- Arixtra® --- n/a --- n/a --- n/a

Solid Catalysts for the Upgrading of Renewable Sources

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ISBN: 9783038975724 Year: Pages: 226 DOI: 10.3390/books978-3-03897-573-1 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Chemistry (General) --- Science (General)
Added to DOAB on : 2019-04-05 11:07:22
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The use of solid catalysts for the upgrade of renewable sources gives the opportunity to combine the two main cores of green chemistry, that is, on the one hand, the set-up of sustainable processes and, on the other, the use of biomass-derived materials. Solid catalysts have taken on a leading role in traditional petrochemical processes and could represent a key tool in new biorefinery-driven technologies.

Bioactive Compounds from Marine-Derived Aspergillus, Penicillium, Talaromyces and Trichoderma Species

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ISBN: 9783038979807 / 9783038979814 Year: Pages: 134 DOI: 10.3390/books978-3-03897-981-4 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology --- Microbiology
Added to DOAB on : 2019-06-26 08:44:06
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The importance of bioactive natural compounds in pharmacology and other biotechnological fields has stimulated the scientific community to explore new environmental contexts and their associated microbial diversity. As the largest frontier in biological discovery, the sea represents a significant source of organisms producing novel secondary metabolites with interesting bioactivities. Of the available biological material, fungi have received increasing consideration, both due to their pervasive occurrence in varying habitats as well as their aptitude to develop symbiotic associations with higher organisms in numerous contexts. In many cases, fungal strains have been reported as the real producers of drugs originally extracted from marine plants and animals. Due to the constantly increasing number of marine-derived fungi yielding valuable bioactive products, it is now appropriate to present these findings to a recipient audience in a more organized form. This Special Issue of Marine Drugs, entitled “Bioactive Compounds from Marine-Derived Aspergillus, Penicillium, Talaromyces, and Trichoderma Species"" is specifically focused on a few genera of ascomycetous fungi which are widespread regarding marine contexts and are particularly inclined to establishing symbiotic relationships. For this project, we welcome submissions of full research papers, short notes, and review articles reporting the discovery and characterization of products showing antibiotic, antitumor, antiviral, insecticidal, antimalarial, antifouling, antioxidant, plant growth-promoting and/or resistance-inducing, as well as other less-exploited activities.

Asymmetric and Selective Biocatalysis

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ISBN: 9783038978466 9783038978473 Year: Pages: 154 DOI: 10.3390/books978-3-03897-847-3 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-06-26 09:16:44
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This Issue contains one communication, six articles, and two reviews. The communication from Paola Vitale et al. represents a work where whole cells were used as biocatalysts for the reduction of optically active chloroalkyl arylketones followed by a chemical cyclization to give the desired heterocycles. Among the various whole cells screened (baker’s yeast, Kluyveromyces marxianus CBS 6556, Saccharomyces cerevisiae CBS 7336, Lactobacillus reuteri DSM 20016), baker’s yeast provided the best yields and the highest enantiomeric ratios (95:5) in the bioreduction of the above ketones. In this respect, valuable chiral non-racemic functionalized oxygen-containing heterocycles (e.g., (S)-styrene oxide, (S)-2-phenyloxetane, (S)-2-phenyltetrahydrofuran), amenable to be further elaborated on, can be smoothly and successfully generated from their prochiral precursors. Studies about pure biocatalysts with mechanistical studies, application in different reactions, and new immobilization methods for improving their stability were reported in five different articles. The article by Su-Yan Wang et al. describes the cloning, expression, purification, and characterization of an N-acetylglucosamine 2-epimerase from Pedobacter heparinus (PhGn2E). For this, several N-acylated glucosamine derivatives were chemically synthesized and used to test the substrate specificity of the enzyme. The mechanism of the enzyme was studied by hydrogen/deuterium NMR. The study at the anomeric hydroxyl group and C-2 position of the substrate in the reaction mixture confirmed the epimerization reaction via ring-opening/enolate formation. Site-directed mutagenesis was also used to confirm the proposed mechanism of this interesting enzyme. The article by Forest H. Andrews et al. studies two enzymes, benzoylformate decarboxylase (BFDC) and pyruvate decarboxylase (PDC), which catalyze the non-oxidative decarboxylation of 2-keto acids with different specificity. BFDC from Pseudomonas putida exhibited very limited activity with pyruvate, whereas the PDCs from S. cerevisiae or from Zymomonas mobilis showed virtually no activity with benzoylformate (phenylglyoxylate). After studies using saturation mutagenesis, the BFDC T377L/A460Y variant was obtained, with 10,000-fold increase in pyruvate/benzoylformate. The change was attributed to an improvement in the Km value for pyruvate and a decrease in the kcat value for benzoylformate. The characterization of the new catalyst was performed, providing context for the observed changes in the specificity. The article by Xin Wang et al. compares two types of biocatalysts to produce D-lysine L-lysine in a cascade process catalyzed by two enzymes: racemase from microorganisms that racemize L-lysine to give D,L-lysine and decarboxylase that can be in cells, permeabilized cells, and the isolated enzyme. The comparison between the different forms demonstrated that the isolated enzyme showed the higher decarboxylase activity. Under optimal conditions, 750.7 mmol/L D-lysine was finally obtained from 1710 mmol/L L-lysine after 1 h of racemization reaction and 0.5 h of decarboxylation reaction. D-lysine yield could reach 48.8% with enantiomeric excess (ee) of 99%. In the article by Rivero and Palomo, lipase from Candida rugosa (CRL) was highly stabilized at alkaline pH in the presence of PEG, which permitted its immobilization for the first time by multipoint covalent attachment on different aldehyde-activated matrices. Different covalent immobilized preparation of the enzyme was successfully obtained. The thermal and solvent stability was highly increased by this treatment, and the novel catalysts showed high regioselectivity in the deprotection of per-O-acetylated nucleosides. The article by Robson Carlos Alnoch et al. describes the protocol and use of a new generation of tailor-made bifunctional supports activated with alkyl groups that allow the immobilization of proteins through the most hydrophobic region of the protein surface and aldehyde groups that allows the covalent immobilization of the previously adsorbed proteins. These supports were especially used in the case of lipase immobilization. The immobilization of a new metagenomic lipase (LipC12) yielded a biocatalyst 3.5-fold more active and 5000-fold more stable than the soluble enzyme. The PEGylated immobilized lipase showed high regioselectivity, producing high yields of the C-3 monodeacetylated product at pH 5.0 and 4 °C. Hybrid catalysts composed of an enzyme and metallic complex are also treated in this Special Issue. The article by Christian Herrero et al. describes the development of the Mn(TpCPP)-Xln10A artificial metalloenzyme, obtained by non-covalent insertion of Mn(III)-meso-tetrakis(p-carboxyphenyl)porphyrin [Mn(TpCPP), 1-Mn] into xylanase 10A from Streptomyces lividans (Xln10A). The complex was found able to catalyze the selective photo-induced oxidation of organic substrates in the presence of [RuII(bpy)3]2+ as a photosensitizer and [CoIII(NH3)5Cl]2+ as a sacrificial electron acceptor, using water as oxygen atom source. The two published reviews describe different subjects with interest in the fields of biocatalysis and mix metallic-biocatalysis, respectively. The review by Anika Scholtissek et al. describes the state-of-the-art regarding ene-reductases from the old yellow enzyme family (OYEs) to catalyze the asymmetric hydrogenation of activated alkenes to produce chiral products with industrial interest. The dependence of OYEs on pyridine nucleotide coenzyme can be avoided by using nicotinamide coenzyme mimetics. In the review, three main classes of OYEs are described and characterized. The review by Yajie Wang and Huimin Zhao highlights some of the recent examples in the past three years that combine transition metal catalysis with enzymatic catalysis. With recent advances in protein engineering, catalyst synthesis, artificial metalloenzymes, and supramolecular assembly, there is great potential to develop more sophisticated tandem chemoenzymatic processes for the synthesis of structurally complex chemicals. In conclusion, these nine publications give an overview of the possibilities of different catalysts, both traditional biocatalysts and hybrids with metals or organometallic complexes to be used in different processes—particularly in synthetic reactions—under very mild reaction conditions.

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