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91.
Udo F. Wehmeier 《Biocatalysis and Biotransformation》2013,31(4-5):279-284
AbstractThe α-glucosidase inhibitor acarbose produced by Actinoplanes sp. SE50/110 is a pseudotetrasaccharide, which consists of an unsaturated cyclitol (carba-sugar), 4-amino-4,6-dideoxyglucose and maltose. The cyclitol (valienol) and the 4-amino-4,6-dideoxyglucose are linked via an N-glycosidic (imino) bond, forming the so-called acarviosyl moiety, which is primarily responsible for the inhibitory effect on α-glucosidases. The gene cluster encoding the biosynthetic genes for the synthesis of acarbose (acb-genes) was sequenced and 25 open reading frames belonging to the acb-gene cluster were identified. Based on the analysis of the enzymes encoded by the acb-cluster, the biosynthesis and ecological role of acarbose is described. The gene cluster includes genes which encode: proteins for the synthesis of the cyclitol; the enzymes for the synthesis of dTDP-4-amino-4,6-dideoxyglucose; glycosyltransferases for the condensation reactions; ATP-dependent exporters and importers; extracellular starch degrading enzymes; and intracellular acarbose modifying enzymes. Acarbose has a dual role for the producer: it inhibits α-glucosidic enzymes of competitors and functions as a carbophor for the uptake of glucose or starch molecules. 相似文献
92.
Environmental variables such as temperature and rainfall can directly affect the community structure of dipterans. Seasonal oscillations in the abundance of species of Drosophilidae reflect differences in how tolerant populations are to climatic conditions. Over a period of 14 months, we collected samples in two habitats in the Pampa biome in the municipality of São Luiz Gonzaga, state of Rio Grande do Sul, Brazil (28°24′28″S, 54°57′39″W). The influence of environmental variables on populations of Drosophilidae was evaluated for both collecting sites by using correlation analysis. The results suggested a negative correlation between the abundances of Drosophila cardinoides Dobzhansky & Pavan, Drosophila maculifrons Duda, Drosophila melanogaster Meigen, Drosophila nigricruria Patterson & Mainland, and Zygothrica vittimaculosa Burla with temperature, which is reflected in the distribution of these species within Brazil. Our findings are important for characterizing and preserving biodiversity in this almost-unknown biome in southern Brazil given the current climate change scenario. 相似文献
93.
Background
Dengue virus (DENV) infections are preferentially diagnosed by detection of specific IgM antibodies, DENV NS1 antigen assays or by amplification of viral RNA in serum samples of the patients. The type-specific immunity to the four worldwide circulating DENV serotypes can be determined by neutralization assays. An alternative to the complicated neutralization assays would be helpful to study the serotype-specific immune response in people in DENV hyperendemic areas but also in subjects upon DENV vaccination.Methods
In consecutive samples of patients with DENV-1- 4 infection type-specific antibodies were detected using an immune complex binding (ICB) ELISA. During incubation of serum samples and enzyme- labeled recombinant envelope domain III (EDIII) antigens immune complexes (ICs) are formed, which are simultaneously bound to a solid phase coated with an Fc–receptor (CD32). After a single washing procedure the bound labeled ICs can be determined. To further improve type-specific reactions high concentrations of competing heterologous unlabeled ED III proteins were added to the labeled antigens.Results
Follow-up serum samples of 64 patients with RT-PCR confirmed primary DENV-1, -2, -3 or -4 infections were tested against four enzyme-labeled recombinant DENV EDIII antigens. Antibodies to the EDIII antigens were found in 55 patients (sensitivity 86%). A complete agreement between the serotype detected by PCR in early samples and the serotype-specific antibody in later samples was found. Type-specific anti-EDIII antibodies were first detected 9–20 days after onset of the disease. In 21% of the samples collected from people in Vietnam secondary infections with antibodies to two serotypes could be identified.Conclusions
The data obtained with the ICB-ELISA show that after primary DENV infection the corresponding type-specific antibodies are detected in almost all samples collected at least two weeks after onset of the disease. The method will be of value to determine the distribution of the various type-specific anti–DENV antibodies in DENV endemic areas. 相似文献94.
Dominic Bresser Elie Paillard Richard Kloepsch Steffen Krueger Martin Fiedler René Schmitz Dietmar Baither Martin Winter Stefano Passerini 《Liver Transplantation》2013,3(4):513-523
The preparation and electrochemical characterization of a new material consisting of carbon coated ZnFe2O4 nanoparticles is presented. This material, which offers an interesting combination of alloying and conversion mechanisms, is capable of hosting up to nine equivalents of lithium per unit formula, corresponding to an exceptional specific capacity, higher than 1000 mAh g?1. Composite electrodes of such a material, prepared using environmentally friendly sodium carboxymethyl cellulose as binder, showed the highest, ever reported, specific capacity and high rate performance upon long‐term testing. Furthermore, in situ X‐ray diffraction analysis allowed identifying the reduction process occurring upon initial lithiation. 相似文献
95.
Mitra Kheirabadi Zohreh Sharafian Hossein Naderi-Manesh Udo Heineman Ulrich Gohlke Saman Hosseinkhani 《Biochimica et Biophysica Acta - Proteins and Proteomics》2013,1834(12):2729-2735
Firefly bioluminescence reaction in the presence of Mg2 +, ATP and molecular oxygen is carried out by luciferase. The luciferase structure alterations or modifications of assay conditions determine the bioluminescence color of firefly luciferase. Among different beetle luciferases, Phrixothrix hirtus railroad worm emits either yellow or red bioluminescence color. Sequence alignment analysis shows that the red-emitter luciferase from Phrixothrix hirtus has an additional arginine residue at 353 that is absent in other firefly luciferases. It was reported that insertion of Arg in an important flexible loop350–359 showed changes in bioluminescence color from green to red and the optimum temperature activity was also increased. To explain the color tuning mechanism of firefly luciferase, the structure of native and a mutant (E354R/356R/H431Y) of Lampyris turkestanicus luciferase is determined at 2.7 Å and 2.2 Å resolutions, respectively. The comparison of structure of both types of Lampyris turkestanicus luciferases reveals that the conformation of this flexible loop is significantly changed by addition of two Arg in this region. Moreover, its surface accessibility is affected considerably and some ionic bonds are made by addition of two positive charge residues. Furthermore, we noticed that the hydrogen bonding pattern of His431 with the flexible loop is changed by replacing this residue with Tyr at this position. Juxtaposition of a flexible loop (residues 351–359) in firefly luciferase and corresponding ionic and hydrogen bonds are essential for color emission. 相似文献
96.
Izelle Smuts Francois H. van der Westhuizen Roan Louw Lodewyk J. Mienie Udo F. H. Engelke Ron A. Wevers Shayne Mason Gerhard Koekemoer Carolus J. Reinecke 《Metabolomics : Official journal of the Metabolomic Society》2013,9(2):379-391
The diagnosis of respiratory chain deficiencies (RCDs) is complicated and the need for a diagnostic biomarker or biosignature has been widely expressed. In this study, the metabolic profile of a selected group of 29 RCD patients, with a predominantly muscle disease phenotype, and 22 controls were investigated using targeted and untargeted analyses of three sub-sections of the human metabolome, including urinary organic acids and amino acids [measured by gas chromatography–mass spectrometry (GC–MS)], as well as acylcarnitines (measured by electrospray ionization tandem MS). Although MS technologies are highly sensitive and selective, they are restrictive by being applied only to sub-sections of the metabolome; an untargeted nuclear magnetic resonance (NMR) spectroscopy approach was therefore also included. After data reduction and pre-treatment, a biosignature comprising six organic acids (lactic, succinic, 2-hydroxyglutaric, 3-hydroxyisobutyric, 3-hydroxyisovaleric and 3-hydroxy-3-methylglutaric acids), six amino acids (alanine, glycine, glutamic acid, serine, tyrosine and α-aminoadipic acid) and creatine, was constructed from uni- and multivariate statistical analyses and verified by cross-validation. The results presented here provide the first proof-of-concept that the metabolomics approach is capable of defining a biosignature for RCDs. We postulate that the composite of organic acids ≈ amino acids > creatine > betaine > carnitines represents the basic biosignature for RCDs. Validated through a prospective study, this could offer an improved ability to assign individual patients to a group with defined RCD characteristics and improve case selection for biopsy procedures, especially in infants and children. 相似文献
97.
Background
The number of patients seeking health care is a central indicator that may serve several different purposes: (1) as a proxy for the impact on the burden of the primary care system; (2) as a starting point to estimate the number of persons ill with influenza; (3) as the denominator data for the calculation of case fatality rate and the proportion hospitalized (severity indicators); (4) for economic calculations. In addition, reliable estimates of burden of disease and on the health care system are essential to communicate the impact of influenza to health care professionals, public health professionals and to the public.Methodology/Principal Findings
Using German syndromic surveillance data, we have developed a novel approach to describe the seasonal variation of medically attended acute respiratory infections (MAARI) and estimate the excess MAARI attributable to influenza. The weekly excess inside a period of influenza circulation is estimated as the difference between the actual MAARI and a MAARI-baseline, which is established using a cyclic regression model for counts. As a result, we estimated the highest ARI burden within the last 10 years for the influenza season 2004/05 with an excess of 7.5 million outpatient visits (CI95% 6.8–8.0). In contrast, the pandemic wave 2009 accounted for one third of this burden with an excess of 2.4 million (CI95% 1.9–2.8). Estimates can be produced for different age groups, different geographic regions in Germany and also in real time during the influenza waves. 相似文献98.
João R. C. Ramos Alexander G. Rath Yvonne Genzel Volker Sandig Udo Reichl 《Biotechnology and bioengineering》2020,117(5):1533-1553
Mathematical modeling of animal cell growth and metabolism is essential for the understanding and improvement of the production of biopharmaceuticals. Models can explain the dynamic behavior of cell growth and product formation, support the identification of the most relevant parameters for process design, and significantly reduce the number of experiments to be performed for process optimization. Few dynamic models have been established that describe both extracellular and intracellular dynamics of growth and metabolism of animal cells. In this study, a model was developed, which comprises a set of 33 ordinary differential equations to describe batch cultivations of suspension AGE1.HN.AAT cells considered for the production of α1-antitrypsin. This model combines a segregated cell growth model with a structured model of intracellular metabolism. Overall, it considers the viable cell concentration, mean cell diameter, viable cell volume, concentration of extracellular substrates, and intracellular concentrations of key metabolites from the central carbon metabolism. Furthermore, the release of metabolic by-products such as lactate and ammonium was estimated directly from the intracellular reactions. Based on the same set of parameters, this model simulates well the dynamics of four independent batch cultivations. Analysis of the simulated intracellular rates revealed at least two distinct cellular physiological states. The first physiological state was characterized by a high glycolytic rate and high lactate production. Whereas the second state was characterized by efficient adenosine triphosphate production, a low glycolytic rate, and reactions of the TCA cycle running in the reverse direction from α-ketoglutarate to citrate. Finally, we show possible applications of the model for cell line engineering and media optimization with two case studies. 相似文献
99.
100.
Samantha A. Spangler Sabine K. Schmitz Josta T. Kevenaar Esther de Graaff Heidi de Wit Jeroen Demmers Ruud F. Toonen Casper C. Hoogenraad 《The Journal of cell biology》2013,201(6):915-928
The presynaptic active zone mediates synaptic vesicle exocytosis, and modulation of its molecular composition is important for many types of synaptic plasticity. Here, we identify synaptic scaffold protein liprin-α2 as a key organizer in this process. We show that liprin-α2 levels were regulated by synaptic activity and the ubiquitin–proteasome system. Furthermore, liprin-α2 organized presynaptic ultrastructure and controlled synaptic output by regulating synaptic vesicle pool size. The presence of liprin-α2 at presynaptic sites did not depend on other active zone scaffolding proteins but was critical for recruitment of several components of the release machinery, including RIM1 and CASK. Fluorescence recovery after photobleaching showed that depletion of liprin-α2 resulted in reduced turnover of RIM1 and CASK at presynaptic terminals, suggesting that liprin-α2 promotes dynamic scaffolding for molecular complexes that facilitate synaptic vesicle release. Therefore, liprin-α2 plays an important role in maintaining active zone dynamics to modulate synaptic efficacy in response to changes in network activity. 相似文献