| 1. |
- Wynberg, Elke, et al.
(författare)
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Variability in white blood cell count during uncomplicated malaria and implications for parasite density estimation : a WorldWide Antimalarial Resistance Network individual patient data meta-analysis
- 2023
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Ingår i: Malaria Journal. - : Springer Nature. - 1475-2875. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Background: The World Health Organization (WHO) recommends that when peripheral malarial parasitaemia is quantified by thick film microscopy, an actual white blood cell (WBC) count from a concurrently collected blood sample is used in calculations. However, in resource-limited settings an assumed WBC count is often used instead. The aim of this study was to describe the variability in WBC count during acute uncomplicated malaria, and estimate the impact of using an assumed value of WBC on estimates of parasite density and clearance.Methods: Uncomplicated malaria drug efficacy studies that measured WBC count were selected from the WorldWide Antimalarial Resistance Network data repository for an individual patient data meta-analysis of WBC counts. Regression models with random intercepts for study-site were used to assess WBC count variability at presentation and during follow-up. Inflation factors for parasitaemia density, and clearance estimates were calculated for methods using assumed WBC counts (8000 cells/mu L and age-stratified values) using estimates derived from the measured WBC value as reference.Results: Eighty-four studies enrolling 27,656 patients with clinically uncomplicated malaria were included. Geometric mean WBC counts (x 1000 cells/mu L) in age groups < 1, 1-4, 5-14 and >= 15 years were 10.5, 8.3, 7.1, 5.7 and 7.5, 7.0, 6.5, 6.0 for individuals with falciparum (n = 24,978) and vivax (n = 2678) malaria, respectively. At presentation, higher WBC counts were seen among patients with higher parasitaemia, severe anaemia and, for individuals with vivax malaria, in regions with shorter regional relapse periodicity. Among falciparum malaria patients, using an assumed WBC count of 8000 cells/mu L resulted in parasite density underestimation by a median (IQR) of 26% (4-41%) in infants < 1 year old but an overestimation by 50% (16-91%) in adults aged = 15 years. Use of age-stratified assumed WBC values removed systematic bias but did not improve precision of parasitaemia estimation. Imprecision of parasite clearance estimates was only affected by the within-patient WBC variability over time, and remained < 10% for 79% of patients.Conclusions: Using an assumed WBC value for parasite density estimation from a thick smear may lead to underdiagnosis of hyperparasitaemia and could adversely affect clinical management; but does not result in clinically consequential inaccuracies in the estimation of the prevalence of prolonged parasite clearance and artemisinin resistance.
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| 2. |
- Hortal, Joaquin, et al.
(författare)
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Perspectives on the use of lakes and ponds as model systems for macroecological research
- 2014
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Ingår i: Journal of limnology. - : Pagepress. - 1129-5767 .- 1723-8633. ; 73:Suppl. 1, s. 46-60
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Tidskriftsartikel (refereegranskat)abstract
- Macroecology studies large-scale patterns aiming to identify the effects of general ecological processes. Although lakes (and ponds) are particularly suited for macroecological research due to their discrete nature and non geographically-structured variability, the development of this discipline in lentic habitats is comparatively much smaller than for terrestrial environments. This is despite the interest of limnologists for large-scale phenomena, which results in the high level of development of some disciplines such as predictive limnology. Here we discuss how current state-of-the-art in macroecology may benefit from research in lentic habitats at five topics. First, by including an island biogeography analytical framework to incorporate the effects of lake origin and history on lentic biodiversity. Second, by studying local and regional effects on the latitudinal gradients of species richness. Third, by considering lakes and ponds altogether for the study of beta diversity and metacommunity structure, which is already common ground in limnological research. Fourth, by relating species traits with ecosystem structure and functioning; here we consider in particular the potential effects of body size-determined dispersal and competitive exclusion processes on lake-wide trophic organization. And fifth, by incorporating current research in functional (i.e., trait) and phylogenetic diversity to the study of community structure. We finally conclude that lentic habitats can be particularly important for the development of the most functional aspects of macroecology, due to the relative ease of studying the different biotic and abiotic components of the system separately, compared to most terrestrial systems. This can allow teasing apart many of the confounding factors that are characteristic of macroecological research, thus helping the development of future theoretical syntheses.
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| 3. |
- Siqueira, Fernanda A., et al.
(författare)
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Metal-Free Synthesis of Indanes by Iodine(III)-Mediated Ring Contraction of 1,2-Dihydronaphthalenes
- 2011
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Ingår i: Journal of the Brazilian Chemical Society. - 0103-5053 .- 1678-4790. ; 22:9, s. 1795-1807
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Tidskriftsartikel (refereegranskat)abstract
- A metal-free protocol was developed to synthesize indanes by ring contraction of 1,2-dihydronaphthalenes promoted by PhI(OH)OTs (HTIB or Koser’s reagent). This oxidative rearrangement can be performed in several solvents (MeOH, CH3CN, 2,2,2-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), and a 1:4 mixture of TFE:CH2Cl2) under mild conditions. The ring contraction diastereoselectively gives functionalized trans-1,3-disubstituted indanes, which are difficult to obtain in synthetic organic chemistry.
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| 4. |
- Yi, Chuixiang, et al.
(författare)
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Climate control of terrestrial carbon exchange across biomes and continents
- 2010
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various ecosystems over six continents with a total of 559 site-years. We find that NEE observed at eddy covariance sites is (1) a strong function of mean annual temperature at mid-and high-latitudes, (2) a strong function of dryness at mid-and low-latitudes, and (3) a function of both temperature and dryness around the mid-latitudinal belt (45 degrees N). The sensitivity of NEE to mean annual temperature breaks down at similar to 16 degrees C (a threshold value of mean annual temperature), above which no further increase of CO2 uptake with temperature was observed and dryness influence overrules temperature influence.
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