Cerebral microbleeds (CMBs) are small foci of (acute, subacute or chronic) blood products, best seen using magnetic resonance imaging (MRI) techniques sensitive to iron deposits (i.e. gradient‐echo ...T2*‐weighted and susceptibility‐weighted imaging), frequently encountered in small vessel disease (SVD) (with hypertensive vasculopathy and cerebral amyloid angiopathy as the most frequent conditions) and also in other disorders. In this review, the MRI characteristics of CMBs and the associated MRI abnormalities encountered in common and less common SVD and non‐SVD conditions are the main focus. Identification of the origin of CMBs depends on their localization, the presence of other associated MRI abnormalities, and the patient's history and clinical state.
•Hetero Janus microparticles made of pectin–alginate were produced by microfluidics.•A fraction of encapsulated BSA diffused from the pectin to the alginate compartment.•Pectin microparticles with ...complex shapes were produced on-chip by μfDISA.•Pectin microparticles with a mushroom morphology stayed at liquid interfaces.
Capillary flow-based approach such as microfluidic devices offer a number of advantages over conventional flow control technology because they ensure highly versatile geometry and can be used to produce monodisperse spherical and non-spherical polymeric microparticles. Based on the principle of a flow-focusing device to emulsify the coflow of aqueous solutions in an organic phase, we were able to produce the following innovative polysaccharide hydrogel microparticles:-Janus hydrogel microparticles made of pectin–pectin (homo Janus) and pectin–alginate (hetero Janus) were produced. The efficiency of separation of the two hemispheres was investigated by confocal scanning laser microscopy (CSLM) of previously labelled biopolymers. The Janus structure was confirmed by subjecting each microparticle hemisphere to specific enzymatic degradation. As a proof of concept, free BSA or BSA grafted with dextran, were encapsulated in each hemisphere of the hetero Janus hydrogel microparticles. While BSA, free or grafted with dextran, was always confined in the alginate hemisphere, a fraction of BSA diffused from the pectin to the alginate hemisphere. Methoxy groups along the pectin chain will be responsible of the decrease of the number of attractive electrostatic interactions occurring between amino groups of BSA and carboxylic groups of pectin.-Pectin hydrogel microparticles of complex shapes were successfully produced by combining on-chip the phenomenon of gelation and water diffusion induced self-assembly, using dimethyl carbonate as continuous phase, or by deformation of the pre-gelled droplets off-chip at a fluid–fluid interface. Sphere, oblate ellipsoid, torus or mushroom-type morphologies were thus obtained. Moreover, it was established that after crossing the interface during their collect, mushroom-type microparticles did not migrate in the calcium or DMC phase but stayed at the liquid–liquid interface.
These new and original hydrogel microparticles will open up opportunities for studying relationships between combined enzymatic hydrolysis and active release for Janus particles and relationships between shape and swelling behaviour for anisotropic pectin microparticles.
Le mode de présentation et les étiologies des hémorragies sous-arachnoïdiennes corticales focales (HSAc), non traumatiques, qui ont fait l’objet de rares séries, diffèrent des hémorragies ...sous-arachnoïdiennes plus diffuses, généralement secondaires à une rupture anévrismale. L’objectif de cette étude est d’en décrire les caractéristiques cliniques, neuroradiologiques et les étiologies retrouvées des HSAc.
Les patients inclus ont présenté une HSAc isolée, définie comme un hyposignal T2 écho de gradient (T2EG) d’un sillon de la convexité sur l’IRM cérébrale initiale, pris en charge dans les services de neurologie des CHU de Nîmes ou de Montpellier de mai 2008 à mai 2011. Un recueil rétrospectif des données a été réalisé pour chaque patient.
Les 23 patients (14 hommes et neuf femmes) inclus avaient un âge moyen de 69,5ans (extrême : 29–86ans). Les patients présentaient le plus souvent des déficits sensitifs ou sensitivomoteurs, régressifs en moins de trente minutes, récidivants, rarement accompagnés de céphalée. L’IRM cérébrale a permis d’identifier des patients avec des hématomes cérébraux anciens (n=2), des microbleeds lobaires (n=7) et des hémosidéroses corticales superficielles (n=6). Une étiologie sera retrouvée chez 43 % (10/23). Les principales étiologies en sont : angiopathie amyloïde cérébrale (n=3), angiopathie cérébrale aiguë réversible (n=2), angéite cérébrale primitive (n=1), syndrome de l’encéphalopathie postérieure réversible (n=1), thrombose veineuse corticale (n=3), dont deux associées à une thrombose des sinus duraux. Sur 11 angiographies cérébrales, réalisées, deux ont permis d’aboutir au diagnostic étiologique (angéite, thrombose des veines corticales). Seize patients ont eu un suivi au long cours (durée moyenne : 12 mois, extrême : trois mois à cinq ans). Ce suivi a permis de définir une étiologie dans deux cas. Il s’agissait de deux angiopathies amyloïdes cérébrales, diagnostiquées sur des hématomes lobaires récidivants.
Les HSAc sont de causes variées, toutefois leur mode de présentation clinique semble être relativement stéréotypé avec des patients présentant des épisodes de déficits sensitivomoteurs, de durées brèves et récidivants. Un bilan exhaustif ainsi que le suivi permettraient d’aboutir à un diagnostic étiologique dans près de la moitié des cas.
Clinical presentation and etiology of localized nontraumatic convexal subarachnoid hemorrhage (cSAH) have been described in a few patients. They differ from those of aneurysmal subarachnoid bleeding which is diffuse. The purpose of this study was to describe the clinical presentation, the radiologic findings and causes of cSAH.
We selected patients admitted to the neurology department of CHU of Nîmes or Montpellier, from May 2008 to May 2011, who presented with cSAH, observed in a single cortical sulcus unrelated to trauma and identified on brain MRI T2* weighted images as a hyposignal in one sulcus of the convexity. Data collection was retrospective.
Twenty-three patients (14 men and nine women) were included. Mean age was 69.5years (range 29–86). Patients had mostly sensory or sensorimotor deficits which was regressive in less than 30minutes, recurrent, and seldom accompanied by headache. Brain MRI allowed the identification of patients with old brain hematomas (n=2), lobar microbleeds (n=7) and superficial cortical hemosiderosis (n=6). The etiologic diagnosis was determined in 43% (n=10/23): cerebral amyloid angiopathy (n=3), reversible cerebral vasoconstriction syndrome (n=2), primary cerebral angiitis (n=1), posterior reversible encephalopathy syndrome (n=1), cortical vein thrombosis (n=3, two of them associated with dural sinus thrombosis). Cerebral angiography was performed in 11 patients and gave the etiologic diagnosis (angiitis, cortical vein thrombosis) in two. Follow-up was available for 16 patients (mean 12months, range 3months to 5years). Etiology was established during follow-up in two patients, both had cerebral amyloid angiopathy diagnosed after recurrent lobar hematomas.
cSAH has various causes, but clinical presentations appear to be relatively stereotyped with recurrent and brief episodes of sensorimotor deficits. A comprehensive assessment and monitoring would lead to an etiologic diagnosis in some patients.
Context
Crop rotations, within-field mixtures, and landscape mosaics including susceptible and resistant crops are three commonly adopted crop diversification strategies that can limit crop ...epidemics. Typically, the effects of crop diversification at these three scales have been studied separately, on single pathogen species, and with low environmental variability.
Objectives
We aim to compare the disease-limitation effect of these three types of crop diversification on two highly damaging fungal pathogens of wheat
Puccinia recondita
(WLR) and
Zymoseptoria tritici
(STB) and under varying weather conditions (warmer or cooler climate for WLR, wetter or drier conditions for STB).
Methods
We built a dynamic mathematical model of epidemics at the field scale (based on classical Susceptible-Exposed-Infectious-Removed epidemiological models) embedded in a spatially explicit landscape grid framework. We use it to simulate an agricultural landscape in which diversification translates into different proportions of wheat and resistant crops in the landscape.
Results
In our simulations, for both pathogens and in all weather conditions, within-field crop mixtures had the greatest impact in limiting epidemics, crop rotations were second-best, while landscape mosaics were the least effective. We also found that the threshold above which further addition of resistant plants to crop mixtures would not cause further disease limitation to be dependent on weather conditions. The more favorable the weather is for pathogens the more resistant plants are required.
Conclusions
Our findings imply that interactions between spatial scale of crop diversification, pathogen characteristics and weather conditions should be considered in order to maximize benefits from disease-regulation properties of diversified cropping systems under climate change.
