Hierarchical Factor Classification of Variables in Ecology

In the analysis of multidimensional ecological data it is often relevant to identify groups of variables, for these groups may reflect similar ecological processes. The usual approach, that is applying well-known clustering procedures to an appropriate similarity measure among the variables, may be criticized, but specific methods for clustering variables are neither largely investigated nor broadly used. Here we introduce a new clustering method for Hierarchical Factor Classification of variables, which is based on the evaluation of the least differences among representative variables of groups, as seen by a two-dimensional Principal Components Analysis. As an additional feature the method gives at each step a principal plane where both grouped variables and units, as seen only by these variables, can be projected. This method can be adapted to count data, so that it may be used for classifying both rows and columns of a contingency data table, by using the chi-square metric. In an example we apply both methods on vegetation and soil data from Campos in South Brazil

Hierarchical factor classification of variables in ecology

In the analysis of multidimensional ecological data, it is often relevant to identify groups of variables since these groups may reflect similar ecological processes. The usual approach, the application of well-known clustering procedures using an appropriate similarity measure among the variables, may be criticized, but specific methods for clustering variables are neither investigated in detail nor used broadly. Here we introduce a new clustering method, the Hierarchical Factor Classification of variables, which is based on the evaluation of the least differences among representative variables of groups, as revealed by a two-dimensional Principal Components Analysis. As an additional feature, the method gives at each step a principal plane where both the grouped variables and the units, considered only according to these variables, can be projected. This method can be adapted to count data, so that it may be used for classifying both rows and columns of a contingency data table, by using the chi-square metric. In an example, we apply both methods to vegetation and soil data from the Campos in Southern Brazil

Vitamin D supplementation, bone turnover, and inflammation in HIV-infected patients

IF 1.307 (2017)International audienceObjectiveTo assess whether vitamin D supplementation could be associated with a modification of inflammatory markers and bone turnover in HIV-1-infected patients.Patients and methodsPatients who participated in an initial survey in 2010 and who were followed in the same department were included in a new study in 2012. Between 2010 and 2012, vitamin D supplementation was offered to patients presenting with hypovitaminosis D as per appropriate guidelines. Clinical examinations were performed, and fasting blood samples were taken for inflammation and bone marker evaluations.ResultsOf the 263 patients who participated in the 2010 study, 198 were included in the 2012 study. Hypovitaminosis D was observed in 47% (36/77) of participants supplemented as per appropriate guidelines, in 78% (75/97) of transiently or incompletely supplemented participants, and in 71% (17/24) of non-supplemented participants (mainly because vitamin D levels in 2010 were normal). No significant correlation between vitamin D supplementation and the 2-year inflammation outcome (IL-6 and hsCRP) or C-terminal telopeptide levels was observed. However, a decrease in IL6 levels over the 2 years significantly correlated with reaching a normal vitamin D level (OR = 0.89 per +1 pg/mL IL6 increase, 95% CI = 0.81–0.97, P = 0.015).ConclusionsVitamin D supplementation decreases the risk of hypovitaminosis D but does not decrease the risk of inflammation nor bone turnover, unless normal 25-OH vitamin D levels are reached.ObjectifsÉvaluer si une supplémentation en vitamine D peut être associée à une modification de l’inflammation et du turn-over osseux chez les personnes vivant avec le VIH (PVVIH).Patients et méthodesToutes les PVVIH d’une étude observationnelle en 2010, suivies dans le même service, ont été incluses dans une nouvelle étude deux ans plus tard. Au cours de ces deux années une supplémentation en vitamine D avait été proposée à celles présentant une hypovitaminose D, selon les recommandations. Une réévaluation clinique a été effectuée après ces deux ans, avec réévaluation biologique de l’inflammation (IL6, CRP) et du remodelage osseux (C-telopeptide X).RésultatsParmi les 198 PPVIH incluses (sur 263 vues en 2010), une hypovitaminose D a été observée en 2012 chez 47 % (36/77) des personnes supplémentées selon les recommandations, chez 78 % (75/97) de celles transitoirement ou partiellement supplémentées, et chez 71 % (17/24) de celles non supplémentées (essentiellement du fait d’un dosage initial de vitamine D normal). Aucune corrélation significative entre la supplémentation en vitamine D et l’évolution à 2 ans des marqueurs de la CRP, de l’IL6 ou du CTX n’a été observée. Une diminution des taux d’IL6 sur les 2 ans était significativement corrélée avec l’obtention d’un taux normal de vitamine D (OR = 0,89 par augmentation de 1 pg/mL d’IL6, IC 95 % = 0,81–0,97, p = 0,015).ConclusionLa supplémentation en vitamine D diminue le risque d’hypovitaminose D mais pas le niveau d’inflammation, à moins d’atteindre un taux de vitamine D normal

European Association for the Study of the Liver (EASL), European Association for the Study of Diabetes (EASD) and European Association for the Study of Obesity (EASO) clinical practice recommendations for the management of non-alcoholic fatty liver diseas: evaluation of their application in people with Type 2 diabetes

IF 3.054International audienceAimsTo evaluate the application of the recently proposed recommendations by the European Association for the Study of the Liver, European Association for the Study of Diabetes and European Association for the Study of Obesity for the diagnosis, treatment and follow-up of non-alcoholic fatty liver disease in people with Type 2 diabetes.MethodsA total of 179 people with Type 2 diabetes were included in this study. Liver fat content (assessed using proton magnetic resonance spectroscopy), fatty liver index score, non-alcoholic fatty liver disease fibrosis score, and SteatoTest and FibroTest scores were determined.ResultsAccording to proton magnetic resonance spectroscopy, 68.7% of participants had steatosis (liver fat content >5.5%). The application of the guidelines using several combinations (fatty liver index + non-alcoholic fatty liver disease fibrosis scores, Steatotest + FibroTest scores, proton magnetic resonance spectroscopy + non-alcoholic fatty liver disease fibrosis score, proton magnetic resonance spectroscopy + FibroTest) resulted in a referral to a liver clinic for 33.5–84.9% people with Type 2 diabetes.ConclusionsThe application of these new algorithms for the diagnosis, and follow-up of non-alcoholic fatty liver disease would lead to an excessive number of people with Type 2 diabetes being referred to a liver clinic. We suggest that new clinical and/or biological biomarkers of steatosis and fibrosis be specifically validated in people with Type 2 diabetes

CRITICAL PEAT project : The importance of hydrology for Carbon Reactivity along with atmosphere - peatland interactions. Preliminary results from the Frasne peatland monitoring (Jura Mountains, France).

International audienceIn the framework of climate changes, peatland ecosystems are compartments of the Critical Zone of growing importance for greenhouse gas (GHG) exchanges with the atmosphere. Peatlands contain about 30 % of the total organic soil carbon worldwide. Interactions of GHG between atmosphere and peatland are potentially controlled by organic matter production and degradation controlled by biotic functiuns, which are in turn influenced by diverse abiotic factors including (1) water saturation, (2) peat humification degree, and (3) water quality conditioning electron acceptor availability. Delineating the detailed roles of these mechanisms is therefore challenging for long-term peatland management, requiring a detailed spatio-temporal monitoring of a wide range of hydrological and biogeochemical parameters.The Frasne peatland (Jura mountains, eastern France), belonging to a regional natural reserve is an outstanding site for such studies as it is monitored since 2008 in the framework of the national observatory of peatlands (SNO Tourbières),and belongs to the Zones Ateliers (RZA) and French Critical Zone (OZCAR) networks supplying the Europe Long-Term Ecosystem Research (eLTER) database (DEIMS-SDR). The peatland took place in a periglacial context on groundmoraines covering a large-scale karstified synclinal structure. This complex geological setting is combined with eco-physical (peat thicknesses and maturity), and hydrological (water-table depth) heterogeneities at the peatland scale.Based on daily hydrometeorological data (P, T, potential evapotranspiration, groundwater level) and monthly monitoring (hydrochemistry; peat lability, GHG fluxes) in 25 piezometers, the goal of the CRITICAL PEAT project is to identify the hydrological and biogeochemical drivers controlling GHG exchanges between peatland and atmosphere. In this perspective, this contribution aims at presenting preliminary results on the hydroclimatic sensitivity of the system inferred from correlation analyses, and its relationships with water origin and chemistry