withdrawn 2017 hrs ehra ecas aphrs solaece expert consensus statement on catheter and surgical ablation of atrial fibrillation

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Alkaloidal Extracts from Avicennia africana P. Beauv. (Avicenniaceae) Leaf: An Antiplasmodial, Antioxidant, and Erythrocyte Viable

Background. The emergence of drug-resistant parasites impedes disease management and eradication efforts. Hence, a reinvigorated attempt to search for potent lead compounds in the mangroves is imperative. Aim. This study evaluates in vitro antiplasmodial activity, antioxidant properties, and cytotoxicity of A. africana leaf alkaloidal extracts. Methods. The A. africana leaves were macerated with 70% ethanol to obtain a total crude extract. Dichloromethane and chloroform-isopropanol (3 : 1, v/v) were used to extract the crude alkaloids and quaternary alkaloids from the total crude. The antiplasmodial activities of the alkaloidal extracts were performed against 3D7 P. falciparum chloroquine-sensitive clone via the SYBR Green I fluorescence assay with artesunate serving as the reference drug. The alkaloidal extracts were further evaluated for antioxidant properties via the total antioxidant capacity (TAC), the total glutathione concentration (GSH), the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, and the ferric-reducing antioxidant power (FRAP) methods. The cytotoxic activity of the alkaloidal extracts was tested on erythrocytes using a 3-(4,5-dimethylthiazol-2-yl)-5-diphenyltetrazolium bromide-MTT assay with little modification. The phytocompounds in the alkaloidal extracts were identified via gas chromatography-mass spectrometry (GC-MS) techniques. Results. The total crude extract showed good antiplasmodial activity (IC50 = 11.890 µg/mL). The crude and quaternary alkaloidal extracts demonstrated promising antiplasmodial effects with IC50 values of 6.217 and 6.285 µg/mL, respectively. The total crude and alkaloidal extracts showed good antioxidant properties with negligible cytotoxicity on erythrocytes with good selectivity indices. The GC-MS spectral analysis of crude alkaloidal extracts gave indole and isoquinoline alkaloids and several other compounds. Dexrazoxane was found to be the main compound predicted, with an 86% peak area in the quaternary alkaloidal extract. Conclusion. The crude and quaternary alkaloidal extracts exhibited antiplasmodial activities and ability to inhibit oxidative stress with negligible toxicity on erythrocytes. This may be good characteristics to avoid oxidative stress related to Plasmodium infection in the treatment of malaria

A glacier respires: Quantifying the distribution and respiration Co₂ flux of cryoconite across an entire Arctic supraglacial ecosystem

] This paper quantifies the mass distribution of cryoconite at the glacier scale using photographic surveys conducted either at ground level, or at 20 m elevation using a novel uninhabited aerial vehicle (UAV). Image acquisition allowed three key deposits to be quantified: cryoconite holes, cryoconite in streams (“stream cryoconite”), and dispersed cryoconite granules (detectable only in the ground-based images). Cryoconite was found all over the snow-free parts of the glacier in one or more of these forms, covering about 0.42% (4600 kg km−2 dry weight) as holes and stream cryoconite deposits (>0.25 cm2 and thus visible in the UAV images), or 1% (10600 kg km−2) when smaller dispersed granules were included (using the ground images). No spatial patterns in the distribution of cryoconite cover were apparent, although cryoconite holes were far more common than stream cryoconite at high altitude due to lower melt rates. Measurements of respiration and bacterial carbon production estimated from in situ incubations of cryoconite–water mixtures indicated rates of 1.174 ± 0.182 (1 standard deviation) and 0.040 ± 0.019 μg C g−1 h−1, respectively. The respiration measurements then yielded glacier-wide CO2 fluxes for 1998 and 2000 of 6.3 and 5.1 kg C km−2 a−1 when the loci and duration of activity were defined using the UAV images and a degree day model, respectively. These fluxes increased to 14 and 12 kg C km−2 a−1 when the dispersed cryoconite detected in the ground-based images were also considered. The measurements therefore show that cryoconite ecosystems clearly have the capacity to impact upon carbon cycling in glacial environments