The emergence of artemisinin (ART) resistance in Plasmodium falciparum intra-erythrocytic parasites has led to increasing treatment failure rates with first-line ART-based combination therapies in ...Southeast Asia. Decreased parasite susceptibility is caused by K13 mutations, which are associated clinically with delayed parasite clearance in patients and in vitro with an enhanced ability of ring-stage parasites to survive brief exposure to the active ART metabolite dihydroartemisinin. Herein, we describe a panel of K13-specific monoclonal antibodies and gene-edited parasite lines co-expressing epitope-tagged versions of K13 in trans. By applying an analytical quantitative imaging pipeline, we localize K13 to the parasite endoplasmic reticulum, Rab-positive vesicles, and sites adjacent to cytostomes. These latter structures form at the parasite plasma membrane and traffic hemoglobin to the digestive vacuole wherein artemisinin-activating heme moieties are released. We also provide evidence of K13 partially localizing near the parasite mitochondria upon treatment with dihydroartemisinin. Immunoprecipitation data generated with K13-specific monoclonal antibodies identify multiple putative K13-associated proteins, including endoplasmic reticulum-resident molecules, mitochondrial proteins, and Rab GTPases, in both K13 mutant and wild-type isogenic lines. We also find that mutant K13-mediated resistance is reversed upon co-expression of wild-type or mutant K13. These data help define the biological properties of K13 and its role in mediating P. falciparum resistance to ART treatment.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Salinipostin A (Sal A) is a potent antiplasmodial marine natural product with an undefined mechanism of action. Using a Sal A-derived activity-based probe, we identify its targets in the Plasmodium ...falciparum parasite. All of the identified proteins contain α/β serine hydrolase domains and several are essential for parasite growth. One of the essential targets displays a high degree of homology to human monoacylglycerol lipase (MAGL) and is able to process lipid esters including a MAGL acylglyceride substrate. This Sal A target is inhibited by the anti-obesity drug Orlistat, which disrupts lipid metabolism. Resistance selections yielded parasites that showed only minor reductions in sensitivity and that acquired mutations in a PRELI domain-containing protein linked to drug resistance in Toxoplasma gondii. This inability to evolve efficient resistance mechanisms combined with the non-essentiality of human homologs makes the serine hydrolases identified here promising antimalarial targets.
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•Semi-synthesis of an affinity analog of the antimalarial natural product Sal A•Identification of serine hydrolases as the primary targets of Sal A in P. falciparum•Sal A covalently binds to and inhibits a MAGL-like protein in P. falciparum•Parasites are unable to generate strong in vitro resistance to Sal A
Using a probe analog of the antimalarial natural product Sal A, Yoo et al. identify its targets as multiple essential serine hydrolases, including a homolog of human monoacylglycerol lipase. Because parasites were unable to generate robust in vitro resistance to Sal A, these enzymes represent promising targets for antimalarial drugs.
To investigate whether a diet with a reduced glycaemic index (GI) has effects on appetite, energy intake, body weight and composition in overweight and obese female subjects.
Randomized crossover ...intervention study including two consecutive 12-week periods. Lower or higher GI versions of key carbohydrate-rich foods (breads, breakfast cereals, rice and pasta/potatoes) were provided to subjects to be incorporated into habitual diets in ad libitum quantities. Foods intended as equivalents to each other were balanced in macronutrient composition, fibre content and energy density.
Nineteen overweight and obese women, weight-stable, with moderate hyperinsulinaemia (age: 34-65 years, body mass index: 25-47 kg m(-2), fasting insulin: 49-156 pmol l(-1)).
Dietary intake, body weight and composition after each 12-week intervention. Subjectively rated appetite and short-term ad libitum energy intake at a snack and lunch meal following fixed lower and higher GI test breakfasts (GI 52 vs 64) in a laboratory setting.
Free-living diets differed in GI by 8.4 units (55.5 vs 63.9), with key foods providing 48% of carbohydrate intake during both periods. There were no differences in energy intake, body weight or body composition between treatments. On laboratory investigation days, there were no differences in subjective ratings of hunger or fullness, or in energy intake at the snack or lunch meal.
This study provides no evidence to support an effect of a reduced GI diet on satiety, energy intake or body weight in overweight/obese women. Claims that the GI of the diet per se may have specific effects on body weight may therefore be misleading.
Diverse compounds target the Plasmodium falciparum Na
pump PfATP4, with cipargamin and (+)-SJ733 the most clinically-advanced. In a recent clinical trial for cipargamin, recrudescent parasites ...emerged, with most having a G358S mutation in PfATP4. Here, we show that PfATP4
parasites can withstand micromolar concentrations of cipargamin and (+)-SJ733, while remaining susceptible to antimalarials that do not target PfATP4. The G358S mutation in PfATP4, and the equivalent mutation in Toxoplasma gondii ATP4, decrease the sensitivity of ATP4 to inhibition by cipargamin and (+)-SJ733, thereby protecting parasites from disruption of Na
regulation. The G358S mutation reduces the affinity of PfATP4 for Na
and is associated with an increase in the parasite's resting cytosolic Na
. However, no defect in parasite growth or transmissibility is observed. Our findings suggest that PfATP4 inhibitors in clinical development should be tested against PfATP4
parasites, and that their combination with unrelated antimalarials may mitigate against resistance development.
Our objective of this study was to explore the bacterial microbiome in fresh or fresh-frozen adult Amblyomma maculatum (Gulf Coast ticks) using extracts enriched for microbial DNA. We collected 100 ...questing adult A. maculatum, surface disinfected them, and extracted DNA from individual ticks collected the same day or after storage at -80 °C. Because only extracts with microbial DNA concentrations above 2 ng/μL were considered suitable for individual analysis, we expected fewer samples to meet these requirements. Of individual ticks extracted, 48 extracts met this minimum concentration. We pooled 20 additional extracts that had lower concentrations to obtain seven additional pools that met the minimum DNA concentration. Libraries created from these 55 samples were sequenced using an Illumina MiSeq platform, and data sets were analyzed using QIIME to identify relative abundance of microorganisms by phylum down to genus levels. Proteobacteria were in greatest abundance, followed by Actinobacteria, Firmicutes, and Bacteroidetes, at levels between 1.9% and 6.4% average relative abundance. Consistent with the Francisella-like endosymbiont known to be present in A. maculatum, the genus Francisella was detected at highest relative abundance (72.9%; SE 0.02%) for all samples. Among the top ten genera identified (relative abundance ≥ 0.5%) were potential extraction kit contaminants, Sphingomonas and Methylobacterium, the soil bacterium Actinomycetospora, and the known A. maculatum-associated genus, Rickettsia. Four samples had Rickettsia at greater than 1% relative abundance, while nine additional samples had Rickettsia at low (0.01-0.04%) relative abundance. In this study, we used the entire microbe-enriched DNA extract for whole ticks for microbiome analysis. A direct comparison of the microbiome in microbe-enriched DNA and total genomic DNA extracts from halves of the same tick would be useful to determine the utility of this extraction method in this system. We anticipate that future tick microbiome studies will be valuable to explore the influence of microbial diversity on pathogen maintenance and transmission, and to evaluate niche-specific microbiomes within individual tick tissues.
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► First detection of Haplosporidium nelsoni in Irish Crassostrea gigas. ► First record of detection of Haplosporidium nelsoni plasmodia in Ostrea edulis. ► Haplosporidium sp., likely ...H. armoricanum, detected in Irish Ostrea edulis.
The phylum Haplosporidia is a group of obligate protozoan parasites that infect a number of freshwater and marine invertebrates. Haplosporidian parasites have caused significant mortalities in commercially important shellfish species worldwide. In this study, haplosporidia were detected in Pacific oysters Crassostrea gigas originating in Ireland and were subsequently identified independently in laboratories both in Ireland and in Spain as Haplosporidium nelsoni. In Ireland, H. nelsoni plasmodia were also observed in the heart tissue of a single Ostrea edulis. A range of techniques including heart smear screening, histology, standard polymerase chain reaction (PCR), direct sequencing and in situ hybridisation with an H. nelsoni specific DNA probe were carried out to confirm diagnosis. This is the first reporting of H. nelsoni in oysters in Ireland and this is the first reporting of the detection of this haplosporidian in O. edulis. In Ireland, another haplosporidian was also observed in a single O. edulis during heart smear screening. PCR and DNA sequencing were carried out and indicated the presence of a Haplosporidium sp., most likely Haplosporidium armoricanum. The low prevalence and intensity of infection of both haplosporidian species in Irish C. gigas and in particular O. edulis may indicate that their presence is inconsequential.
Continuous compositional zoning in amphibole grains in strongly deformed and lineated amphibolites from the Eastern Blue Ridge, North Carolina indicates that most of the deformation was accommodated ...by dissolution–precipitation creep. Amphibole in most samples shows moderate prograde and/or retrograde zoning parallel to the long‐axis with compositions ranging between magnesiohornblende and tschermakite. In one sample, grains are zoned from actinolitic (Si = 7.9 p.f.u.) cores to tschermakitic (Si = 6.2 p.f.u) rims. Amphibole‐plagioclase thermometry suggests prograde growth temperatures as low as 400 °C, but typically range from 650 to 730 °C and retrograde growth temperatures <700 °C. These estimates are corroborated quantitatively with amphibole‐garnet‐plagioclase thermobarometry and qualitatively with a positive correlation between TiO2 concentration in amphibole and calculated temperature. This growth zoning provides persuasive evidence that amphibole precipitation produced the fabric, but evidence for dissolution is less common. It is present, however in the form of truncations of complicated zoning patterns produced by healed fractures and overgrowths in low‐temperature cores by high‐temperature tschermakitic grains lacking similar internal structures. The preservation of this network of straight cracks filled with optically continuous amphibole also provides evidence against the operation of dislocation creep even to temperatures >700 °C because dislocation‐creep would have deformed the fracture network. Thus, these amphibolites deformed by dissolution–precipitation creep that produced a strong linear fabric under upper amphibolite facies, middle‐to‐lower crustal conditions. The significance of this discovery is that dissolution–precipitation creep is activated at lower stresses than dislocation creep and that the strength of the lower crust, where amphibole is the dominant mineral is probably lower than that derived from experimental studies.
Background: Spasticity and loss of function in an affected arm are common after stroke. Although botulinum toxin is used to reduce spasticity, its functional benefits are less easily demonstrated. ...This paper reports an exploratory meta-analysis to investigate the relationship between reduced arm spasticity and improved arm function. Method: Individual data from stroke patients in two randomised controlled trials of intra-muscular botulinum toxin were pooled. The Modified Ashworth Scale (elbow, wrist, fingers) was used to calculate a “Composite Spasticity Index”. Data from the arm section of the Barthel Activities of Daily Living Index (dressing, grooming, and feeding) and three subjective measures (putting arm through sleeve, cleaning palm, cutting fingernails) were summed to give a “Composite Functional Index”. Change scores and the time of maximum change were also calculated. Results: Maximum changes in both composite measures occurred concurrently in 47 patients. In 26 patients the improvement in spasticity preceded the improvement in function with 18 showing the reverse. There was a definite relationship between the maximum change in spasticity and the maximum change in arm function, independent of treatment (ρ = −0.2822, p = 0.0008, n = 137). There was a clear relationship between the changes in spasticity and in arm function in patients treated with botulinum toxin (Dysport) at 500 or 1000 units (ρ = −0.5679, p = 0.0090, n = 22; ρ = −0.4430, p = 0.0018, n = 47), but not in those treated with placebo or 1500 units. Conclusions: Using a targeted meta-analytic approach, it is possible to demonstrate that reducing spasticity in the arm is associated with a significant improvement in arm function.
Oxidative stress markers as well as high concentrations of copper are found in the vicinity of A beta amyloid deposits in Alzheimer's disease. The neurotoxicity of A beta in cell culture has been ...linked to H sub(2)O sub(2) generation by an unknown mechanism. We now report that Cu(II) markedly potentiates the neurotoxicity exhibited by A beta in cell culture. The potentiation of toxicity is greatest for A beta 1-42 > A beta 1-40 >> mouse/rat A beta 1-40, corresponding to their relative capacities to reduce Cu(II) to Cu(I), form H sub(2)O sub(2) in cell-free assays and to exhibit amyloid pathology. The copper complex of A beta 1-42 has a highly positive formal reduction potential ( approximately +500-550 mV versus Ag/AgCl) characteristic of strongly reducing cuproproteins. These findings suggest that certain redox active metal ions may be important in exacerbating and perhaps facilitating A beta -mediated oxidative damage in Alzheimer's disease.
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