62 research outputs found

    Tetramic acid based alkaloids from Aspergillus amoenus Roberg strain UP197-antibiotic properties and new pyranterreones

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    The fungus Aspergillus amoenus Roberg strain UP197 was shown to produce antibacterial tetramic acid based alkaloids. Two new compounds, pyranterreone I and J (1 and 2), were isolated and characterized, in addition to the known compounds cordylactam, 7-hydroxycordylactam, pyranterreone C, D, F and G. Neither the pyranterreones nor the cordylacctams had previously been tested for antimicrobial activity. Thus, all isolated compounds were tested against a panel of clinically important bacteria and fungi. Pyranterreone C was active against Gram-positive and Gram-negative bacteria, with minimal inhibitory concentrations (MIC) between 1 and 8 mu g/mL, whereas the MICs for all other compounds were >32 mu g/mL. Pyranoterreone C was cytotoxic towards HepG2 cells, and since pyranterreone C reacted rapidly with the nucleophile cysteine, it is likely that the observed antibacterial activity is due to the chemical reactivity rather than enzymatic affinity, making it unsuitable for development as an antibacterial drug

    Exoplanet Atmosphere Measurements from Transmission Spectroscopy and other Planet-Star Combined Light Observations

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    It is possible to learn a great deal about exoplanet atmospheres even when we cannot spatially resolve the planets from their host stars. In this chapter, we overview the basic techniques used to characterize transiting exoplanets - transmission spectroscopy, emission and reflection spectroscopy, and full-orbit phase curve observations. We discuss practical considerations, including current and future observing facilities and best practices for measuring precise spectra. We also highlight major observational results on the chemistry, climate, and cloud properties of exoplanets.Comment: Accepted review chapter; Handbook of Exoplanets, eds. Hans J. Deeg and Juan Antonio Belmonte (Springer-Verlag). 22 pages, 6 figure

    Preclinical Assessment of the Treatment of Second-Stage African Trypanosomiasis with Cordycepin and Deoxycoformycin

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    There is an urgent need to substitute the highly toxic arsenic compounds still in use for treatment of the encephalitic stage of African trypanosomiasis, a disease caused by infection with Trypanosoma brucei. We exploited the inability of trypanosomes to engage in de novo purine synthesis as a therapeutic target. Cordycepin was selected from a trypanocidal screen of a 2200-compound library. When administered together with the adenosine deaminase inhibitor deoxycoformycin, cordycepin cured mice inoculated with the human pathogenic subspecies T. brucei rhodesiense or T. brucei gambiense even after parasites had penetrated into the brain. Successful treatment was achieved by intraperitoneal, oral or subcutaneous administration of the compounds. Treatment with the doublet also diminished infection-induced cerebral inflammation. Cordycepin induced programmed cell death of the parasites. Although parasites grown in vitro with low doses of cordycepin gradually developed resistance, the resistant parasites lost virulence and showed no cross-resistance to trypanocidal drugs in clinical use. Our data strongly support testing cordycepin and deoxycoformycin as an alternative for treatment of second-stage and/or melarsoprol-resistant HAT

    A Review of Probabilistic Risk Assessment of Contaminated Land (12 pp)

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    Improved identification of Streptococcus bovis-Streptococcus equinus-complex species and subspecies by MALDI-TOF MS using a novel library

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    ObjectivesTo develop an in-house matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) library for improved identification of species and subspecies of the Streptococcus bovis/Streptococcus equinus-complex (SBSEC).Methods236 SBSEC isolates from blood stream infections and culture collections, determined by whole genome sequencing to subspecies level, were grown in brain heart infusion broth. Mass spectra were collected using the Bruker MALDI Biotyper system after ethanol-formic acid extraction. Main spectral profiles from 117 isolates were used to create the “SBSEC-CMRS library”. The remaining 119 spectra were used for evaluation of Bruker MBT Compass Library Revision K (2022) and the SBSEC-CMRS library.ResultsThe Bruker library correctly identified species and subspecies in 72/119 (61 %) isolates, while the SBSEC-CMRS library identified 116/119 (97 %), using a cutoff score of ≄2.0.ConclusionsThe SBSEC-CMRS library showed sufficient diagnostic accuracy, and can be implemented in clinical practice for SBSEC species and subspecies identification.KeywordsStreptococcus bovisStreptococcus gallolyticusMALDI-TOF MSsubspecies identificationAbbreviationsMALDI-TOF MSMatrix-assisted laser desorption/ionization time-of-flight mass spectrometrySBSECStreptococcus bovis/Streptococcus equinus-complexCMRSClinical Microbiology Region SkĂ„neSBSEC-CMRS libraryStreptococcus bovis/Streptococcus equinus-complex-Clinical Microbiology Region SkĂ„ne librarySg pasteurianusStreptococcus gallolyticus subsp. pasteurianusSg gallolyticusStreptococcus gallolyticus subsp. gallolyticusSg macedonicusS. gallolyticus subsp. macedonicusSi infantariusS. infantarius subsp. infantariusBHIBrain heart infusionWGSWhole genome sequencin
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