oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 60 )

2018 ( 66 )

2017 ( 90 )

2016 ( 98 )

Custom range...

Search Results: 1 - 10 of 32294 matches for " Peter Kusch "
All listed articles are free for downloading (OA Articles)
Page 1 /32294
Display every page Item
In Vitro and In Vivo Antimalarial Activity Assays of Seeds from Balanites aegyptiaca: Compounds of the Extract Show Growth Inhibition and Activity against Plasmodial Aminopeptidase
Peter Kusch,Susanne Deininger,Sabine Specht,Rudeka Maniako,Stefanie Haubrich,Tanja Pommerening,Paul Kong Thoo Lin,Achim Hoerauf,Annette Kaiser
Journal of Parasitology Research , 2011, DOI: 10.1155/2011/368692
Abstract: Balanites aegyptiaca (Balanitaceae) is a widely grown desert plant with multiuse potential. In the present paper, a crude extract from B. aegyptiaca seeds equivalent to a ratio of 1?:?2000 seeds to the extract was screened for antiplasmodial activity. The determined IC50 value for the chloroquine-susceptible Plasmodium falciparum NF54 strain was 68.26? . Analysis of the extract by gas chromatography-mass spectrometry detected 6-phenyl-2(H)-1,2,4-triazin-5-one oxime, an inhibitor of the parasitic M18 Aspartyl Aminopeptidase as one of the compounds which is responsible for the in vitro antiplasmodial activity. The crude plant extract had a of 2.35? and showed a dose-dependent response. After depletion of the compound, a significantly lower inhibition was determined with a of 4.8? . Moreover, two phenolic compounds, that is, 2,6-di-tert-butyl-phenol and 2,4-di-tert-butyl-phenol, with determined IC50 values of 50.29? and 47.82? , respectively, were detected. These compounds may contribute to the in vitro antimalarial activity due to their antioxidative properties. In an in vivo experiment, treatment of BALB/c mice with the aqueous Balanite extract did not lead to eradication of the parasites, although a reduced parasitemia at day 12 p.i. was observed. 1. Introduction Traditional medicine is still the first point of healthcare for many people in sub-Saharan Africa, where there has been a long and rich tradition of obtaining treatments from herbs and trees. In the case of malaria, Africa’s traditional healers use hundreds of indigenous plants for remedies. Until the 1950s, when synthetic chemistry began to dominate drug research and development (R and D) efforts, most drugs developed and registered in the pharmacopoeia were in fact based on natural products. Plant alkaloids, quinine among them, were the first components of natural herbal remedies to be extracted and refined for more effective use in the early 19th century. Some 150 years later, quinine is still used as front-line therapy for severe malaria, even if it is not the recommended drug for this use when artemisinin combination therapies (ACTs) are available. In this context, it seems to be quite surprising that no African lead has emerged so far. Meanwhile, there are efforts to assess plant remedies against malaria for their application in health care systems [1]. B. aegyptiaca (L.) (Balanitaceae) is a woody tree growing in various ecological conditions (from 100?mm to 1000?mm annual rainfall), but mainly distributed in semiarid and arid zones in tropical Africa [2]. This tree reaches 10?m (33?ft)
Gold as a Potential Contrast Agent for Dual-Energy CT  [PDF]
Radko Krissak, Martin Elgert, Bj?rn Kusch, Ralph Hünerbein
Advances in Molecular Imaging (AMI) , 2013, DOI: 10.4236/ami.2013.34006
Abstract:

Purpose: The K-edge of gold (81 keV) is located within the energy range of diagnostic CT. This might be advantageous for material differentiation in dual-energy CT (DECT). The aim of this in vitro study was to compare the differentiation between iodine or gold and body tissues using DECT at different kV spectra. Methods and Materials: A water filled tank phantom containing specimens with iodine (iopamidol), gold (sodium aurothiomalate), compact bone (compact porcine bone) and porcine muscle was scanned using a dual source CT (Definition, Siemens Healthcare). Consecutive scans were performed at 80 kVp, 100 kVp, 120 kVp and 140 kVp with constant mAs settings. The mean attenuation values of the specimens were measured, and differences in calculated dual-energy ratios (DEratio) between body tissues and iodine or gold were determined for different DE spectra. Results: The attenuation of gold increased compared to 80 kVp at higher kVp-settings, while the attenuation of all other specimens decreased. The calculated DEratios at 80/100 kVp, 80/120 kVp and 80/140 kVp were 1.31, 1.62 and 1.91 for iodine, 0.89, 0.88 and 0.92 for gold, 1.20, 1.39 and 1.45 for compact bone, 1.01, 1.03 and 1.08 for muscle. The differences between the DEratios 80/100 kVp, 80/120 kVp and 80/140 kVp were 0.11, 0.23 and 0.46 for iodine and bone, 0.31, 0.51 and 0.53 for gold and bone, 0.29, 0.59 and 0.83 for iodine and muscle, 0.12, 0.15 and 0.16 for gold and muscle. Conclusion: DEratio of gold remains relatively stable along the energy spectrum of diagnostic CT and allows a reliable material differentiation between gold and bone already at contiguous low tube voltage settings (80 kV and 100 kV). Thus, gold might have a potential as a contrast agent for DECT.

Integration of Lignocellulosic Biomass into Renewable Energy Generation Concepts
KUSCH Sigrid,Maria V. MORAR
Proenvironment Promediu , 2009,
Abstract: In all European countries various lignocellulosic biomasses such as agricultural residues (straw, strawcontaining dung) or fractions from municipal solid waste are available in large amounts, but currently hardly any of thispotential is being used for energy generation. This paper reviews the different options for including lignocellulosicbiomass into renewable energy generation schemes. Not all wastes are suitable to be treated by principally availabletechniques such as anaerobic digestion, ethanol production or thermal valorisation. The present paper gives an overviewof utilisation options for lignocellulosic biomass to either produce biofuels or to integrate such biomass into anaerobicdigestion. Biorefinery concepts are discussed as well.
Sobre la distribución del Pingüino Rey Aptenodytes Patagonicus (Aves: Spheniscidae) en Chile On the distribution of the King Penguin Aptenodytes Patagonicus (Aves: Spheniscidae) in Chile
Alejandro Kusch,Manuel Marín
Anales del Instituto de la Patagonia , 2012,
Abstract:
DISTRIBUCIóN DE LA BECASINA GRANDE GALLINAGO STRICKLANDII (Gray, 1845) (SCOLOPACIDAE), EN CHILE DISTRIBUTION OF THE FUEGUIAN SNIPE GALLINAGO STRICKLANDII (Gray, 1845) (SCOLOPACIDAE), IN CHILE
Alejandro Kusch,Manuel Marín
Anales del Instituto de la Patagonia , 2010,
Abstract:
Probability Fluxes and Transition Paths in a Markovian Model Describing Complex Subunit Cooperativity in HCN2 Channels
Klaus Benndorf ,Jana Kusch,Eckhard Schulz
PLOS Computational Biology , 2012, DOI: 10.1371/journal.pcbi.1002721
Abstract: Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are voltage-gated tetrameric cation channels that generate electrical rhythmicity in neurons and cardiomyocytes. Activation can be enhanced by the binding of adenosine-3′,5′-cyclic monophosphate (cAMP) to an intracellular cyclic nucleotide binding domain. Based on previously determined rate constants for a complex Markovian model describing the gating of homotetrameric HCN2 channels, we analyzed probability fluxes within this model, including unidirectional probability fluxes and the probability flux along transition paths. The time-dependent probability fluxes quantify the contributions of all 13 transitions of the model to channel activation. The binding of the first, third and fourth ligand evoked robust channel opening whereas the binding of the second ligand obstructed channel opening similar to the empty channel. Analysis of the net probability fluxes in terms of the transition path theory revealed pronounced hysteresis for channel activation and deactivation. These results provide quantitative insight into the complex interaction of the four structurally equal subunits, leading to non-equality in their function.
Preferencias de hábitat del ?andú (Rhea Pennata D'orbigni, 1834) en matorrales intervenidos en Chile austral
Kusch,Alejandro; Marcos Henríquez,J;
Anales del Instituto de la Patagonia , 2011, DOI: 10.4067/S0718-686X2011000100003
Abstract: in the steppes of southern chile, a commonly used management strategy for vegetation includes clear-cutting strips of shrubs in order to maximize the growth of forage plant species for sheep ranching. the lesser rhea (rhea pennata), an endemic, fightless bird species categorized as “vulnerable” is an inhabitant in these ecosystems. the aim of the study was to determine the relationship between vegetation variables and habitat preferences of lesser rheas in sites with and without this shrubland management. lesser rheas were found to prefer sites with medium level disturbance of shrubs and avoided control site (without management). habitat preferences of a determinated management unit could be explained because the resulting habitat type provides shelter and food supplies simultaneously. these results suggest that maintaining medium cover of shrubs is an action that favorably affects rhea populations, but it is necessary to evaluate the spatial design of clear cutting as well.
Preferencias de hábitat del andú (Rhea Pennata D'orbigni, 1834) en matorrales intervenidos en Chile austral Habitat preferences of Lesser Rhea (Rhea Pennata D'orbigni, 1834) in disturbed shrubland of austral Chile
Alejandro Kusch,J Marcos Henríquez
Anales del Instituto de la Patagonia , 2011,
Abstract: En la estepa de Chile austral comúnmente se realiza manejo de la vegetación mediante la erradicación de matorral en franjas para favorecer el crecimiento de plantas forrajeras para el ganado ovino. Un habitante endémico y con categoría de conservación “vulnerable” es el andú (Rhea pennata), ave no voladora que habita en este ecosistema. Se determinó la relación con variables de la vegetación y preferencia del hábitat del andú en sitios con erradicación de matorral y sin intervención. El andú prefrió sitios con erradicación intermedia del matorral y rechazó sitios sin intervención. La preferencia por una unidad de manejo en particular podría explicarse porque provee de refugio y alimentación de manera simultánea. Esto implica que el corte del matorral manteniendo la mitad de la cobertura inicial es una medida que favorece a las poblaciones de andú, pero de igual forma debe evaluarse el dise o espacial de la intervención. In the steppes of southern Chile, a commonly used management strategy for vegetation includes clear-cutting strips of shrubs in order to maximize the growth of forage plant species for sheep ranching. The Lesser Rhea (Rhea pennata), an endemic, fightless bird species categorized as “vulnerable” is an inhabitant in these ecosystems. The aim of the study was to determine the relationship between vegetation variables and habitat preferences of Lesser rheas in sites with and without this shrubland management. Lesser Rheas were found to prefer sites with medium level disturbance of shrubs and avoided control site (without management). Habitat preferences of a determinated management unit could be explained because the resulting habitat type provides shelter and food supplies simultaneously. These results suggest that maintaining medium cover of shrubs is an action that favorably affects rhea populations, but it is necessary to evaluate the spatial design of clear cutting as well.
AVES ACUáTICAS EN EL HUMEDAL URBANO DE TRES PUENTES, PUNTA ARENAS (53° S), CHILE AUSTRAL
Kusch,Alejandro; Cárcamo,Jaime; Gómez,Humberto;
Anales del Instituto de la Patagonia , 2008, DOI: 10.4067/S0718-686X2008000200005
Abstract: urban wetlands are sites with high biodiversity but with anthropic pressure if not well manage. in punta arenas city (53°s), tres puentes is a unique wetland to create a site with all conservation components (education, research, sustainable development). we report waterfowl species composition and abundance during 6 breeding season is reported. there were 31 species, corresponding 50% of continental waterfowl of magallanes region. interannual variability in species richness, abundance and possible anthropic impacts are discussed.
Implications for chloro- and pheopigment synthesis and preservation from combined compound-specific δ13C, δ15N, and Δ14C analysis
S. Kusch,Y. Kashiyama,N. O. Ogawa,M. Altabet
Biogeosciences Discussions , 2010, DOI: 10.5194/bgd-7-6265-2010
Abstract: Chloropigments and their derivative pheopigments preserved in sediments can directly be linked to photosynthesis. Their carbon and nitrogen stable isotopic compositions have been shown to be a good recorder of recent and past surface ocean environmental conditions tracing the carbon and nitrogen sources and dominant assimilation processes of the phytoplanktonic community. In this study we report results from combined compound-specific radiocarbon and stable carbon and nitrogen isotopic analysis to examine the timescales of synthesis and fate of chlorophyll-a and its degradation products pheophytin-a, pyropheophytin-a, and 132,173-cyclopheophorbide-a-enol until burial in Black Sea surface sediments. The pigments are mainly of marine phytoplanktonic origin as implied by their stable isotopic compositions. Pigment δ15N values indicate nitrate as the major uptake substrate but 15N-depletion towards the open marine setting indicates contribution from N2-fixation. Radiocarbon concentrations translate into minimum and maximum pigment ages of approximately 40 to 1200 years. This implies that protective mechanisms against decomposition such as association with minerals or eutrophication-induced hypoxia and light limitation are much more efficient than previously thought. However, seasonal variations of nutrient source, growth period, and habitat and their associated isotopic variability are likely at least as strong as long-term trends. Combined triple isotopic analysis of sedimentary chlorophyll and its primary derivatives is a powerful tool to delineate biogeochemical and diagenetic processes in the surface water and assess their precise timescales.
Page 1 /32294
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.