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Arseni Pacheco i Ransanz (1932-2011) Arseni Pacheco i Ransanz (1932-2011)
Curt Wittlin
Llengua & Literatura , 2012, DOI: 10.2436/l&l.v0i0.60567
Die Rebhühner des Eiximenis: Gott r cht auch Mord an Nicht-Christen. (Zum Gedenken seines sechshundertsten Todestages) [The partridges of Eiximenis: on the occasion of the 600th year of his death]
Wittlin, Curt
Zeitschrift für Katalanistik , 2010,
Abstract: This article gives an overview of the public and academic activities that have been organized in 2009, the 600th year of the death of the famous Valencian preacher and philosopher, and sheds light on the importance of his work.
Francesc Eiximenis i les seves fonts
Curt J. Wittlin
Llengua & Literatura , 2003, DOI: 10.2436/l&l.vi.1050
Per què els interessa als canadencs el Dotzè del Crestià de Francesc Eiximenis?
Curt J. Wittlin
Llengua & Literatura , 1998, DOI: 10.2436/l&l.vi.1251
Francesc Eiximenis i la Bíblia : qüestions pràctiques sobre edició i indexació d'al·lusions i citacions
Curt J. Wittlin
Llengua & Literatura , 2009, DOI: 10.2436/l&l.vi.1290
Especulacions psicoanalítiques sobre la sexualitat en el Tirant lo Blanc
Curt J. Wittlin
Llengua & Literatura , 1998, DOI: 10.2436/l&l.vi.1013
In vitro interaction of artemisinin derivatives or the fully synthetic peroxidic anti-malarial OZ277 with thapsigargin in Plasmodium falciparum strains
Abiodun Oyindamola O,Brun Reto,Wittlin Sergio
Malaria Journal , 2013, DOI: 10.1186/1475-2875-12-43
Abstract: Background Semi-synthetic artemisinin derivatives are powerful peroxidic drugs in artemisinin-based combination therapy (ACT) recommended as first-line treatment of Plasmodium falciparum malaria in disease-endemic countries. Studies by Eckstein-Ludwig and co-workers showed both thapsigargin and artemisinin specifically inhibit the sarcoplasmic reticulum Ca2+ ATPase of Plasmodium falciparum (PfATP6). In the present study the type of interaction between thapsigargin and artemisinin derivatives as well as the ozonide OZ277 (RBx11160 or arterolane) was evaluated in parasite cultures. The latter compound is an adamantane-based peroxide and the first fully synthetic clinical candidate recently registered in India by Ranbaxy Laboratories Ltd. for anti-malarial combination therapy. Methods Drug interaction studies were performed using a previously described fixed ratio method and anti-malarial activity measured using the [3H] hypoxanthine incorporation assay. Results The sum 50% and 90% fractional inhibitory concentration (∑FIC50, 90) of the interaction of thapsigargin with OZ277, artemether or artesunate, against NF54 and K1 strains of P. falciparum ranged from 0.9 to 1.4. Conclusion The interaction of thapsigargin with OZ277, artesunate or artemether was additive, data consistent with previous observations indicating that activity of anti-malarial peroxides does not derive from reversible interactions with parasite targets.
A new double-antibody sandwich ELISA targeting Plasmodium falciparum aldolase to evaluate anti-malarial drug sensitivity
Lucienne Tritten, Hugues Matile, Reto Brun, Sergio Wittlin
Malaria Journal , 2009, DOI: 10.1186/1475-2875-8-226
Abstract: The newly developed double-antibody sandwich ELISA described here is based on the properties of a non-overlapping pair of monoclonal antibodies directed against Plasmodium falciparum aldolase. This glycolytic enzyme possesses some unique nucleotide sequences compared to the human isoenzymes and has been highly conserved through evolution. Out of twenty possibilities, the most sensitive antibody pair was selected and used to quantitatively detect parasite aldolase in infected blood lysates.A total of 34 compounds with anti-malarial activity were tested side-by-side by ELISA and the [3H]hypoxanthine incorporation assay. The novel ELISA provided IC50s closely paralleling those from the radioactivity-based assay (R = 0.99, p < 0.001). At the investigated assay conditions (72 h incubation time, parasitaemia = 0.3%), the assay was found to be reproducible and easy to perform.The newly developed ELISA presents several advantages over the comparative method, the [3H]hypoxanthine incorporation assay. The assay is highly reproducible, less hazardous (involves no radioactivity) and requires little and cheap technical equipment. Relatively unskilled personnel can conduct this user-friendly assay. All this makes it attractive to be employed in resource-poor laboratories.Several techniques exist to measure anti-malarial activity of chemical compounds. The most commonly used method, especially in well-equipped laboratories, is the [3H]hypoxanthine incorporation assay [1]. This method is highly reproducible, however, the handling of radioactive material is costly, hazardous and quite complex and, therefore, problematic for resource-poor locations. Moreover, radioactive material is not uniformly authorized worldwide, limiting its application geographically. A low-cost alternative is the schizont maturation assay, standardized by the World Health Organization. However, this test can only be carried out by the experienced microscopist, is very labour-intensive and prone to individual
Isothermal Microcalorimetry, a New Tool to Monitor Drug Action against Trypanosoma brucei and Plasmodium falciparum
Tanja Wenzler ,Andrea Steinhuber,Sergio Wittlin,Christian Scheurer,Reto Brun,Andrej Trampuz
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001668
Abstract: Isothermal microcalorimetry is an established tool to measure heat flow of physical, chemical or biological processes. The metabolism of viable cells produces heat, and if sufficient cells are present, their heat production can be assessed by this method. In this study, we investigated the heat flow of two medically important protozoans, Trypanosoma brucei rhodesiense and Plasmodium falciparum. Heat flow signals obtained for these pathogens allowed us to monitor parasite growth on a real-time basis as the signals correlated with the number of viable cells. To showcase the potential of microcalorimetry for measuring drug action on pathogenic organisms, we tested the method with three antitrypanosomal drugs, melarsoprol, suramin and pentamidine and three antiplasmodial drugs, chloroquine, artemether and dihydroartemisinin, each at two concentrations on the respective parasite. With the real time measurement, inhibition was observed immediately by a reduced heat flow compared to that in untreated control samples. The onset of drug action, the degree of inhibition and the time to death of the parasite culture could conveniently be monitored over several days. Microcalorimetry is a valuable element to be added to the toolbox for drug discovery for protozoal diseases such as human African trypanosomiasis and malaria. The method could probably be adapted to other protozoan parasites, especially those growing extracellularly.
Ancient Chinese Methods Are Remarkably Effective for the Preparation of Artemisinin-Rich Extracts of Qing Hao with Potent Antimalarial Activity
Colin W. Wright,Peter A. Linley,Reto Brun,Sergio Wittlin,Elisabeth Hsu
Molecules , 2010, DOI: 10.3390/molecules15020804
Abstract: Ancient Chinese herbal texts as far back as the 4th Century Zhou hou bei ji fang describe methods for the use of Qing Hao (Artemisia annua) for the treatment of intermittent fevers. Today, the A. annua constituent artemisinin is an important antimalarial drug and the herb itself is being grown and used locally for malaria treatment although this practice is controversial. Here we show that the ancient Chinese methods that involved either soaking, (followed by wringing) or pounding, (followed by squeezing) the fresh herb are more effective in producing artemisinin-rich extracts than the usual current method of preparing herbal teas from the dried herb. The concentrations of artemisinin in the extracts was up to 20-fold higher than that in a herbal tea prepared from the dried herb, but the amount of total artemisinin extracted by the Chinese methods was much less than that removed in the herbal tea. While both extracts exhibited potent in vitro activities against Plasmodium falciparum, only the pounded juice contained sufficient artemisinin to suppress parasitaemia in P. berghei infected mice. The implications of these results are discussed in the context of malaria treatment using A. annua infusions.
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