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Les maladies des petits vaisseaux cérébraux sont des affections extrêmement fréquentes touchant tous les âges. Si les formes les plus fréquentes liées à l'âge et à l'hypertension artérielle ou à l'angiopathie amyloïde cérébrale sont essentiellement des pathologies des sujets de plus de 50 ans, il existe des formes plus rares qui touchent les sujets jeunes, parfois même les enfants. Certaines formes familiales ou inflammatoires peuvent être particulièrement trompeuses avec des présentations parfois très difficiles à relier à une origine microvasculaire. Les maladies des petits vaisseaux cérébraux posent donc des problèmes thérapeutiques quotidiens et des problèmes diagnostiques plus rares mais parfois extrêmement complexes. L'objet de cette revue est donc de rappeler les principales présentations inaugurales et les spectres clinico-radiologiques des affections qui y sont associées. Cerebral small vessel diseases are frequent and can be seen through all ages. Although the most frequent forms related to age and hypertension or to cerebral amyloid angiopathy are mainly observed in subjects over 50 years of age, rarer forms may affect young people, sometimes even children. Some familial or inflammatory forms can be particularly misleading with some presentations very difficult to relate to a microvascular origin. Cerebral small vessel diseases thus raise both daily therapeutic issues and much rarer diagnostic questions, sometimes extremely complex. Our aim was to review the main clinical initial presentations and the clinico-radiological spectrum of associated underlying conditions. [ABSTRACT FROM AUTHOR]

Edge contrast, is one of the main determinants of edge effects. This study examines the response of plant and pollinator diversity (bees and butterflies) to forest edge contrast, i.e. the difference between forests and adjacent open habitats with different disturbance regimes. We also investigated a potential cascading effect from plants to pollinators and whether edge structure and landscape composition mediate the relationship between edge contrast and beta diversity of pollinators. We sampled 51 low-contrast edges where forests were adjacent to habitats showing low levels of disturbance (i.e. grey dunes, mowed fire-breaks, orchards, grasslands) and 29 high-contrast edges where forests were adjacent to more intensively disturbed habitats (i.e. tilled firebreaks, oilseed rape) in three regions of France. We showed that plant diversities were higher in edges than in adjacent open habitat, whatever the edge contrast. However, plant beta diversity did not differ significantly between low and high-contrast edges. While we observed higher pollinator diversities in adjacent habitats than in low-contrast edges, there were no significant differences in pollinator beta diversity depending on edge contrast. We did not observe a cascading effect from plants to pollinators. Plant and bee beta diversities were mainly explained by local factors (edge structure and flower cover) while butterfly beta diversity was explained by surrounding landscape characteristics (proportion of land cover in grassland). [ABSTRACT FROM AUTHOR]

Although action slowing is the main cognitive impairment in stroke survivors, its mechanisms and determinants are still poorly understood. The objectives of the present study were to determine the mechanisms of post-stroke action slowing (using validated, highly specific simple reaction time (SRT) and tapping tests) and identify its imaging determinants (using multivariate lesion-symptom mapping (mLSM)). Action speed in the GRECogVASC cohort was assessed using finger tapping and SRT tests performed with both hands and analyzed using previously validated indices. Imaging determinants were identified using validated mLSM analyses and disconnection analysis and compared to those of an fMRI activation meta-analytic database. Both the tapping time and SRT were 10.7% slower for the 394 patients (p = 0.0001) than for the 786 controls, without a group × test interaction (p = 0.2). The intra-individual distribution curve was characterized by a rightward shift with an unaltered attentional peak. The mLSM analyses showed tapping to be associated with lesions in the frontostriatal tract (p = 0.0007). The SRT was associated with lesions in the frontostriatal tract (p = 0.04) and the orbital part of F3 (p = 0.0001). The SRT-tapping index was associated with lesions in the orbital part of F3 (p = 0.0001). All lesions were located in the right hemisphere only and were responsible for the disconnection of several structures involved in motor preparation, initiation, and speed. A comparison with fMRI activation meta-analytic data highlighted mostly the same regions, including the orbital part of F3, the ventral and dorsal parts of F1, and the premotor and cingulate regions in the right hemisphere. Our results confirm the marked impairment of action speed in stroke and show that the primary mechanism is motor slowing and that it is related to lesions in the right frontostriatal tract. A deficit in sustained alertness accounted for action slowing in the subgroup with lesions in the right orbital part of F3. Our SRT and mLSM results were in accordance with the fMRI activation data. Thus, stroke induces slowing in the broad network associated with SRT tasks by disrupting the frontostriatal tract and, to a lesser extent, other sites involved in attention. • Poststroke action slowing is mainly secondary to motor slowing. • It is mainly due to frontostriatal tract lesion. • Attentional impairment is less frequent and secondary to right F3 lesion. [ABSTRACT FROM AUTHOR]

Introduction La biopsie musculaire n'est habituellement pas réalisée pour le diagnostic de sclérose latérale amyotrophique (SLA). Son aspect anatomopathologique dans cette maladie est varié, et peut mimer une pathologie inflammatoire du muscle, engendrant des discussions diagnostiques. Observation Nous rapportons le cas d'un homme de 50 ans dont les principaux antécédents sont une hernie discale L5-S1 opérée avec douleurs neurogènes résiduelles traitées par pregabaline, une hypertension artérielle traitée par perindopril et un tabagisme sevré. Le patient consulte pour des myalgies diffuses avec faiblesse musculaire prédominant sur les groupes musculaires proximaux évoluant depuis un an, accompagnées de crampes, de fasciculations et de troubles de la déglutition. L'examen neurologique ne retrouvait ni syndrome pyramidal ni argument pour une neuropathie périphérique. Le bilan biologique mettait en évidence une rhabdomyolyse avec un pic de créatine phosphokinase (CPK) à 4000 UI/l, se stabilisant ensuite à 400 UI/l. Le bilan étiologique comprenant la recherche de causes infectieuse, endocrinienne, auto-immune (dont le DOT-myosite) et médicamenteuse était négatif. L'électromyogramme (EMG) retrouvait un syndrome neurogène sévère diffus, axonal, aux quatre membres, avec un tracé le plus souvent simple accéléré hypervolté, sans syndrome myogène. Il existait également une atteinte bulbaire. Devant l'importance de la rhabdomyolyse initiale, nous avons réalisé une biopsie musculaire qui montrait un aspect évoquant le diagnostic de dermatomyosite. En effet, il existait des foyers de nécrose focale des fibres musculaires avec foyers de régénération, un infiltrat inflammatoire mononuclée avec une composante lymphocytaire principalement CD4 + , prédominant dans le périmysium en périvasculaire. La discussion diagnostique se fait entre une SLA rapidement progressive et une myosite. Devant la suspicion de dermatomyosite, le patient a bénéficié d'une corticothérapie (1 mg/kg/jour de PREDNISONE) associée à des immunoglobulines polyvalentes (2 g/kg toutes les 4 semaines). L'évolution clinique est marquée par l'aggravation progressive du déficit moteur à prédominance proximale. L'examen clinique mettait en évidence une amyotrophie, des réflexes ostéotendineux vifs, sans signes de Babinski ou Hoffman, ainsi que des fasciculations. Devant la progression des symptômes, un nouvel EMG est réalisé, retrouvant toujours une atteinte neurogène pure, sans atteinte musculaire. L'imagerie médullaire et la ponction lombaire étant normales, le diagnostic de SLA est retenu. Discussion La SLA est une pathologie neurodégénérative touchant le premier et deuxième motoneurone. Le diagnostic est évoqué devant une atteinte neurologique motrice pure évoluant de manière progressive et associant un syndrome pyramidal et un syndrome neurogène périphérique. L'EMG permet alors d'affirmer le diagnostic [1]. La biopsie musculaire n'est pas nécessaire au diagnostic. Lorsqu'elle est réalisée, elle peut montrer des lésions de dénervation avec une atrophie des cellules musculaires en groupe et une hypertrophie compensatrice des cellules musculaires voisines. Il peut également exister des lésions d'aspect myopathiques avec des cellules musculaires nécrosées, parfois associées à un infiltrat lymphocytaire du perimysium (à prédominance CD4 +) [2]. La distinction avec une myosite peut alors être difficile. Dans une étude menée sur 111 biopsies de patients avec SLA, 8 étaient strictement normales, 28 montraient des lésions de dénervations et 75 montraient des lésions myopathiques dont 11 avec un infiltrat mononucléaire. Deux prélèvements ne permettaient pas de faire la distinction avec une myopathie inflammatoire [2]. Les lésions myopathiques sont plus fréquemment associées à une élévation modérée des CPK, généralement inférieure à 3 fois la normale [3]. Cependant, les deux pathologies peuvent coexister, d'autant plus que la SLA est plus fréquente chez les patients atteints de maladies auto-immunes, notamment dans la polymyosite, une autre forme de myopathie inflammatoire [1]. Conclusion Le diagnostic différentiel entre SLA et myopathie inflammatoire peut parfois s'avérer difficile, les deux pathologies pouvant partager des lésions histologiques similaires à la biopsie musculaire. L'évolution clinique du patient (notamment la réponse au traitement entrepris) ainsi que le renouvellement des examens complémentaires permettent alors de redresser le diagnostic. [ABSTRACT FROM AUTHOR]

Landscape heterogeneity is an important driver of biodiversity in agroecosystems. However, the functional heterogeneity of agricultural landscapes, taking into account the different resources that habitat patches can provide to species, has rarely been studied. In this study, we explored the effect of landscape-scale nest availability provided by permanent grasslands on wild bee communities. Wild bees were sampled in 43 cereal fields in south-western France differing in the surrounding proportion of permanent grasslands. Using remote sensing tools, we measured two parameters of grassland structure known to locally influence bee nest density (slope and proportion of sparse vegetation). We found that mean slope of surrounding grasslands was the factor that most positively influenced bee richness, abundance and trait distribution in bee communities. We also found that mean slope of surrounding grasslands had a better predictive power of bee community structure than the proportion of permanent grasslands. Ground-nesting species, species with high dispersal capacities and species with a generalist diet were positively affected by the availability of sloped ground in the surrounding permanent grasslands. Only bee species with specialized flower requirements responded positively to the proportion of sparse vegetation in grasslands. Our results suggest that landscape-scale availability of nesting resources provided by grasslands affects bee communities in agricultural landscapes and can help sustain functionally diverse bee assemblages. Using simple remote sensing tools, this study highlights the importance of considering nesting resources in agricultural landscapes to maintain wild bee diversity in farmlands. [ABSTRACT FROM AUTHOR]

In agricultural landscapes, permanent grassy habitats are often fragmented and partly composed of linear elements. Landscape-level connectivity of both grassland patches and grassy linear elements actively contributes to biodiversity conservation in farmland. Nevertheless, their respective importance has rarely been tested. Butterflies form a suitable model group for this purpose; they have suffered a major overall decline in the last few decades and are known to be sensitive to landscape connectivity. We sampled 286 transects nested in 18 study landscapes in three regions. Using several metrics, we analyzed the response of butterflies to the connectivity to both grassland and woodland habitats, which may provide additional resources. The response to landscape connectivity appeared to depend on the type of the semi-natural elements (patch vs linear elements), and on species traits, i.e. the response was stronger for habitat specialists and species with low dispersal ability. We found that woody habitats close to grassland patches had a significant positive effect on butterfly communities, denoting potential mechanisms of resources supplementation and complementation. In grassy linear elements, butterfly communities were of lower conservation value, richness and abundance were much lower (− 26 and − 50%) than in grassland patches and decreased with isolation from grasslands, in line with the source–sink hypothesis. Although grassy linear elements probably play an important role in butterfly dispersal in agricultural landscapes, they may not be sufficient to preserve specialist and sedentary species. Conserving a mosaic of high quality grassland patches and woody habitats appears more effective than enhancing connectivity. [ABSTRACT FROM AUTHOR]

Experiments in exclosures were conducted on a salt marsh in a macrotidal system in western France. The aim of this study was threefold: (1) to compare vegetation dynamics over a period of 8 years in grazed and ungrazed conditions (2) to investigate the response of annual species to grazing duration during seedling establishment (3) to test the effect of an increase in soil nitrogen availability after cessation of grazing on interactions between Suaeda maritima and Puccinellia maritima. In grazed conditions, during all the survey, vegetation was dominated by a short P. maritima sward with the annual Salicornia europaea in the lower and middle marshes. However, after cessation of grazing in 1994, a homogeneous matrix of the forb Halimione portulacoides, quickly replaced P. maritima in the well drained lower marsh. At the middle marsh level, fine sediment and poor drainage maintained P. maritima while the annual S. maritima which tolerates taller and denser vegetation replaced S. europaea. Elymus pungens cover was limited till 2000 but its rising in 2001 let expect its dominance in the future. While P. maritima abundance remained high, spring abundance of annual species such as S. europaea and S. maritima globally decreased with sheep grazing duration on the salt marsh between February and June. Experiments with monocultures of P. maritima and S. maritima demonstrated that nitrogen was a limiting factor on the salt marsh. In a mixed community, a moderate application of nitrogen (15 g N m–2 year–1 as NH4-NO3) promoted growth of P. maritima and limited the biomass of S. maritima, but growth of the latter was enhanced by a high application of nitrogen (30 g N m–2 year–1). An increase in the abundance of annuals such as S. maritima on the salt marsh is discussed. [Copyright &y& Elsevier]

Le pomalidomide est un agent immunomodulateur de la famille des IMiDs (comme le thalidomide et le lenalidomide) utilisé dans le myélome multiple et ayant participé à l'augmentation de l'espérance de vie des patients atteints de cette pathologie. Il présente différents effets secondaires dont le risque thrombotique et la toxicité hématologique. Nous rapportons le cas d'une hyperéosinophilie chez un patient sous pomalidomide dans le cadre d'un myélome multiple. Il s'agit d'un patient présentant un myélome diagnostiqué en 1998 et ayant bénéficié de plusieurs lignes de traitement. À la suite d'une rechute, le patient bénéficie début 2016 d'un traitement par Pomalidomide et Dexamethasone auquel est associé en octobre 2017 un traitement par Daratumumab devant une réévolutivité sur le plan osseux. Dans les semaines suivant l'introduction de pomalidomide, il présente une hyperéosinophilie fluctuante. Le patient n'avait jamais présenté d'hyperéosinophilie auparavant. Dans le cadre du bilan de cette hyperéosinophilie, aucune cause évidente n'est retrouvée. La recherche de FIP1L1-PDGFRA est revenue négative. Le traitement d'épreuve antiparasitaire n'a été d'aucune efficacité. La biopsie ostéo-médullaire ne montrait pas de syndrome myéloprolifératif. Nous avons ensuite réalisé des hémogrammes à plusieurs reprises en fonction de la prise du pomalidomide. Le traitement était pris pendant 3 semaines lors de cycles de 28 jours. Le taux d'éosinophile était à 971/mm3, 1418/mm3, 2500/mm3, 1200/mm3, 1290/mm3, 600/mm3 respectivement à J5, J18, J21, J23, J25 et J27 (cf courbe). On constate donc une augmentation du taux lors de la prise du pomalidomide et une diminution lors de la pause d'une semaine. Nous retrouvons des résultats similaires au cours d'autres cycles. Le score d'imputabilité selon la méthode internationalement reconnue (de Narenjo et al.) est de 9, ce qui montre une imputabilité certaine du pomalidomide. Cependant, le patient n'a pour le moment présenté aucune complication liée à cette hyperéosinophilie. Le traitement a donc été poursuivi. Le pomalidomide est un des traitements récents du myélome multiple en rechute. Il constitue un réel progrès dans le traitement du myélome en améliorant la survie des patients réfractaires. Certains effets indésirables, comme le risque thrombotique ou la toxicité hématologique, sont bien connus. La démarche diagnostique concernant l'hyperéosinophilie chez ce patient a permis d'éliminer les autres causes en dehors de l'origine iatrogène. À notre connaissance, nous rapportons pour la première fois le cas d'un patient présentant une hyperéosinophilie sous pomalidomide, dont l'imputabilité est certaine. [ABSTRACT FROM AUTHOR]

Farming intensity and landscape heterogeneity influence agrobiodiversity and associated ecological functions. The relative contributions of these agroecosystem components to agricultural production remain unclear because of inter-relations and weather-dependant variations. Using a structural equation modelling approach, we estimated direct and indirect contributions of farming intensity (soil management, pesticide use and fertilisation) and landscape heterogeneity (of semi-natural covers and crop mosaic) to cereal crop production, in 54 fields (mostly wheat), in two years (24 and 30 fields). Indirect effects were evaluated through agrobiodiversity (carabid and plant communities) and ecological functions (pollination and pest control). In 2016, farming intensity had the largest direct positive effect on cereal crop yield, followed by agrobiodiversity (74% of the farming intensity impact) and ecological functions. However, the direct benefits of farming intensity were halved due to negative indirect effects, as farming intensity negatively affected within-field biodiversity and ecological functions. Overall, agrobiodiversity and farming intensity had equal net contributions to cereal crop yields, while heterogeneity of the crop mosaic enhanced biodiversity. In 2017, neither higher farming intensity nor agrobiodiversity and ecological functions could lift cereal production, which suffered from unfavourable meteorological conditions. Semi-natural habitats supported agrobiodiversity. Our study suggests that a reduction of farming intensity combined with higher heterogeneity of crop mosaic can enhance the benefits of ecological functions towards crop production. Semi-natural covers seem to play an essential role in the face of climatic events, by supporting agrobiodiversity and the potential resilience of the agroecosystem functioning. • Agrobiodiversity and farming intensity equally supported cereal production. • Farming intensity indirectly affected crop yield through ecological functions. • Landscape heterogeneity enhanced agrobiodiversity and ecological functions. • Crop yields and ecological functions are vulnerable to meteorological events. • Agroecological transition requires recognising intensive farming is counterproductive. [ABSTRACT FROM AUTHOR]

The prediction of grasslands plant diversity using satellite image time series is considered in this article. Fifteen months of freely available Sentinel optical and radar data were used to predict taxonomic and functional diversity at the pixel scale (10 m × 10 m) over a large geographical extent (40,000 km2). 415 field measurements were collected in 83 grasslands to train and validate several statistical learning methods. The objective was to link the satellite spectro-temporal data to the plant diversity indices. Among the several diversity indices tested, Simpson and Shannon indices were best predicted with a coefficient of determination around 0.4 using a Random Forest predictor and Sentinel-2 data. The use of Sentinel-1 data was not found to improve significantly the prediction accuracy. Using the Random Forest algorithm and the Sentinel-2 time series, the prediction of the Simpson index was performed. The resulting map highlights the intra-parcel variability and demonstrates the capacity of satellite image time series to monitor grasslands plant taxonomic diversity from an ecological viewpoint. • Plant diversity of grasslands is estimated using Sentinel-2 time series. • Large intra-parcel variability in terms of plant diversity index is observed. • Large scale prediction is done using random forest regression. • Sentinel-1 time series could complement Sentinel-2 time series. [ABSTRACT FROM AUTHOR]