Pantropical variability in tree crown allometry

Aim Tree crowns determine light interception, carbon and water exchange. Thus, understanding the factors causing tree crown allometry to vary at the tree and stand level matters greatly for the development of future vegetation modelling and for the calibration of remote sensing products. Nevertheless, we know little about large‐scale variation and determinants in tropical tree crown allometry. In this study, we explored the continental variation in scaling exponents of site‐specific crown allometry and assessed their relationships with environmental and stand‐level variables in the tropics. Location Global tropics. Time period Early 21st century. Major taxa studied Woody plants. Methods Using a dataset of 87,737 trees distributed among 245 forest and savanna sites across the tropics, we fitted site‐specific allometric relationships between crown dimensions (crown depth, diameter and volume) and stem diameter using power‐law models. Stand‐level and environmental drivers of crown allometric relationships were assessed at pantropical and continental scales. Results The scaling exponents of allometric relationships between stem diameter and crown dimensions were higher in savannas than in forests. We identified that continental crown models were better than pantropical crown models and that continental differences in crown allometric relationships were driven by both stand‐level (wood density) and environmental (precipitation, cation exchange capacity and soil texture) variables for both tropical biomes. For a given diameter, forest trees from Asia and savanna trees from Australia had smaller crown dimensions than trees in Africa and America, with crown volumes for some Asian forest trees being smaller than those of trees in African forests. Main conclusions Our results provide new insight into geographical variability, with large continental differences in tropical tree crown allometry that were driven by stand‐level and environmental variables. They have implications for the assessment of ecosystem function and for the monitoring of woody biomass by remote sensing techniques in the global tropics

Infections hivernales et Médecines complémentaires (Prévention par stimulation du système immunitaire)

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Mise au point sur quelques plantes dites antidiabétiques

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

La validation des procédés de fabrication des produits dermo-cosmétiques et OTC

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Intra-specific variability of allometric relationships between tree outer dimensions in four species of a tropical monsoon forest in the Western Ghats of India

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Altered postprandial lipemia and fatty acid handling in obese vs. Normal-weight men is rectified by reducing dietary fat load: A dose-response trial

International audienceBackground Postprandial hyperlipemia and altered dietary lipid beta-oxidation are now recognized as metabolic risk factors in obesity that are directly associated with dietary fat intake. The amount and size of chylomicrons are known to impact their clearance and thus possibly modulate the final partitioning of dietary fatty acids (FA) between β-oxidation and storage, which is altered in obesity. However, the detailed impact of ingested fat amount on postprandial lipemia and dietary FA fate in obese subjects remains to be elucidated. Methods In a randomized crossover study, eighteen healthy normal-weight (NW) and obese men ingested meals containing 10g or 40g of fat (typical breakfast fat contents) labeled with a mix of 13C-triglyceride tracers. Chylomicron triglyceride content and size were measured during 8h of digestion. Plasma concentrations of 13C-palmitate and 13C-oleate were also measured during 8h in parallel with their fecal loss (72h-stool collection). 13CO2 breath-test coupled to indirect calorimetry measures during 8h allowed to calculate exogenous lipid fate. Results Chylomicron triglycerides increased in all subjects according to ingested fat amount (P<0.01). After 40g of fat, obese men had delayed postprandial lipemia compared to NW men (PtimexBMI<0.0001) especially at 5–8h post-breakfast (P<0.01), with different variations in chylomicron size (PtimexBMI<0.01). This was associated with a lower appearance of tracers in plasma in obese men (P<0.01 for AUC 0–5h vs. NW), and a tendency to higher fecal excretion of 13C-oleate (P=0.1 vs. NW) after 40g of fat. However after 10g of fat, chylomicron TG and size, and tracer kinetics and fecal loss, were similar regardless of BMI. Finally, the impact of fat amount on exogenous lipid β-oxidation was different according to BMI (PdosexBMI<0.01): 39.6% of ingested lipids were β-oxidized after 40g of fat in obese (vs. 45.1% in NW) but this was increased to 53.1% in obese for 10g of fat (vs. 49.7% in NW subjects; P<0.001 vs. 40g). Conclusions Postprandial lipemia profile after a realistic high-fat load is altered in obese subjects. Although the reduction of ingested fat amount seems to normalize the postprandial fate of dietary lipids in obese men, further research is needed to understand mechanisms of altered postprandial lipid metabolism in obesity

Mortality and recruitment in a lowland tropical rain forest of French Guiana: effects of soil type and species guild

A-07-11International audienceA variety of processes have been identified as playing a key role in maintenance of hyper-rich tropical forest, among which ecological sorting caused by niche partitioning challenges stochastic dispersal processes. However, demographic responses to spatio-temporal resource variation that could result in biased species distributions are still little studied. In this paper we investigate from two censuses, c. 15 y apart, of a 12-ha permanent forest sample in French Guiana, how tree recruitment and mortality rates vary among hydrological soil types known to affect species habitat preferences and among ecological guilds related to species light requirement. The results indicate that both recruitment and mortality vary significantly with respect to these factors. While the mean instantaneous mortality and recruitment rates are estimated to 0.98 and 0.81%, respectively, pioneer species, canopy trees and hydromorphic bottomland soils depart significantly from these values. In particular, the pioneers, regenerating either from the soil seed bank or from post-opening seed rain, show faster dynamics than other species. These two guilds harbour probabilities of mortality elevated by a factor of 1.9 and 3.2, respectively, and probabilities of recruitment elevated by a factor of 4.9 and 3.1, respectively. Conversely, canopy trees show slower dynamics, with probabilities of mortality and recruitment lowered by a mean factor of about 0.5 with respect to other species. We also observe that trees growing in hydromorphic bottomlands prove to have significantly higher mortality and recruitment probabilities, by a factor of about 2 with respect to those growing in terra firme

13C tracer recovery in human stools after digestion of a fat-rich meal labelled with [1,1,1-13C3]tripalmitin and [1,1,1-13C3]triolein

International audienceLipid metabolism studies focus mainly on oxidation and storage but rarely on faecal elimination, which is needed to assess total lipid distribution during the postprandial period. The purpose of the present work was to set up and validate the analysis of lipid tracers in stools, with an aim of later using this methodology in studies of postprandial lipid tracer metabolism. Eight subjects received a mixture of [1,1,1-(13)C3]tripalmitin and [1,1,1-(13)C3]triolein with a fat-rich meal. The nature and amounts of (13)C lipids excreted in stools during 3 days post-dose were determined by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analysis of fatty acid methyl esters (FAMEs) from total fatty acid (TFA), free fatty acid (FFA) and triacylglycerol (TAG) fractions. The results were expressed as the Cumulative Tracer Recovery of the administered dose (CTR%). The quantities and labelling of FAMEs were higher in FFA than in TAG, indicating that label loss was not due to a lack of digestive lipase activity. The labelling was higher for C16:0 than for C18:1. The CTRs were 7.03 ± 0.77% and 6.87 ± 0.91%, respectively, in TFA and FFA for [1-(13)C] C16:0, while they were 0.60 ± 0.15% and 0.51 ± 0.11% for [1-(13)C] C18:1 (mean ± sem). By studying the kinetics of lipid excretion from subjects, two groups emerged. The first one showed rapid excretion in stool #1, whereas the second showed slower excretion in stools #2-#3. A significant difference was found in the FFA in stool #1 for C16:0 (p < 0.01) and C18:1 (p < 0.05). Individual excretion kinetics showed marked variability. Nevertheless, the CTR over the 3-day study period was substantial and homogenous for all subjects. These results confirm that the assessment of faecal elimination is of great importance when establishing total lipid distribution during the postprandial period and validate the analysis of cumulative tracer loss during 72 h post-tracer ingestion

Relying on the French territorial offer of thermal spa therapies to build a care pathway for long COVID-19 patients

International audienceBackground Work on long COVID-19 has mainly focused on clinical care in hospitals. Thermal spa therapies represent a therapeutic offer outside of health care institutions that are nationally or even internationally attractive. Unlike local care (hospital care, general medicine, para-medical care), their integration in the care pathways of long COVID-19 patients seems little studied. The aim of this article is to determine what place french thermal spa therapies can take in the care pathway of long COVID-19 patients. Methods Based on the case of France, we carry out a geographic mapping analysis of the potential care pathways for long COVID-19 patients by cross-referencing, over the period 2020–2022, the available official data on COVID-19 contamination, hospitalisations in intensive care units and the national offer of spa treatments. This first analysis allows us, by using the method for evaluating the attractiveness of an area defined by David Huff, to evaluate the accessibility of each French department to thermal spas. Results Using dynamic geographical mapping, this study describes two essential criteria for the integration of the thermal spa therapies offer in the care pathways of long COVID-19 patients (attractiveness of spa areas and accessibility to thermal spas) and three fundamental elements for the success of these pathways (continuity of the care pathways; clinical collaborations; adaptation of the financing modalities to each patient). Using a spatial attractiveness method, we make this type of geographical analysis more dynamic by showing the extent to which a thermal spa is accessible to long COVID-19 patients. Conclusion Based on the example of the French spa offer, this study makes it possible to place the care pathways of long COVID-19 patients in a wider area (at least national), rather than limiting them to clinical and local management in a hospital setting. The identification and operationalization of two geographical criteria for integrating a type of treatment such as a spa cure into a care pathway contributes to a finer conceptualization of the construction of healthcare pathways

Author Correction: Disturbance Regimes Drive The Diversity of Regional Floristic Pools Across Guianan Rainforest Landscapes (vol 8, 3872, 2018)

Correction to: Scientifc Reports https://doi.org/10.1038/s41598-018-22209-9, published online 01 March 2018International audienc