Implication of scavenger receptors in the interactions between diesel exhaust particles and immature or mature dendritic cells

Background  

The exposure to pollutants such as diesel exhaust particles (DEP) is associated with an increased incidence of respiratory diseases. However, the mechanisms by which DEP have an effect on human health are not completely understood. In addition to their action on macrophages and airway epithelial cells, DEP also modulate the functions of dendritic cells (DC). These professional antigen-presenting cells are able to discriminate unmodified self from non-self thanks to pattern recognition receptors such as the Toll like Receptors (TLR) and Scavenger Receptors (SR). SR were originally identified by their ability to bind and internalize modified lipoproteins and microorganisms but also particles and TLR agonists. In this study, we assessed the implication of SR in the effects of DEP associated or not with TLR agonists on monocyte-derived DC (MDDC). For this, we studied the regulation of CD36, CXCL16, LOX-1, SR-A1 and SR-B1 expression on MDDC treated with DEP associated or not with TLR2, 3 and 4 ligands. Then, the capacity of SR ligands (dextran sulfate and maleylated-ovalbumin) to block the effects of DEP on the function of lipopolysaccharide (LPS)-activated DC has been evaluated.     

Dam,Environment and Regional Development: Case Study of the Logone Floodplain in Northern Cameroon

The purpose of this paper is a study of environmental change in the Logone floodplain in northern Cameroon following the construction in the 1970s of a dam for a rice irrigation project. This unique ecosystem, designated as a biosphere reserve for supporting an impressive wildlife population, depends on the annual overflowing of the lowland. Several communities living in the plain rely upon water and natural resources of the floodplain to support recession agriculture, the fisheries, wetland rice and livestock. But both persistently poor rainfalls in the Sahel and the adverse impacts of the dam have devastated the area, forcing a large number of people to leave. This paper gives the scope of this situation based on geospatial information and field investigation, and also early results of the floodplain rehabilitation programme conducted since 1994 under the supervision of the World Wildlife Fund. In addition to demonstrating the potential of geomatics technology in environmental hazard assessment, this case study highlights the complexity of water-related issues in areas of conflicting interests. Despite significant improvements achieved by the rehabilitation programme, there is still much work to complete for the area to recover its former biodiversity.     

Opposite effects of osteogenic protein and transforming growth factor beta on chondrogenesis in cultured long bone rudiments

Osteogenic protein-1 (OP-1, also called BMP-7) is a bone morphogenetic member of the TGF-beta superfamily. In the present study, we examined the effect of recombinant human OP-1 on cartilage and bone formation in organ cultures of metatarsal long bones of mouse embryos and compared the OP-1 effects with those of human TGF-beta 1 and porcine TGF-beta 1 and beta 2. Cartilage formation was determined by measurement of longitudinal growth of whole bone rudiments during culture and by the incorporation of 35SO4 into glycosaminoglycans. Mineralization was monitored by 45Ca incorporation in the acid-soluble fraction and by measuring the length of the calcifying center of the rudiment. Toluidine blue-stained histologic sections were used for quantitative histomorphometric analysis. We found that OP-1 stimulated cartilage growth as determined by sulfate incorporation and that it increased remarkably the width of the long bones ends compared with controls. This effect was partly caused by differentiation of perichondrial cells into chondrocytes, resulting in increased appositional growth. In contrast to OP-1, TGF-beta 1 and beta 2 inhibited cartilage growth and reduced the length of whole bone rudiments compared with controls. In the ossifying center of the bone rudiments, both OP-1 and TGF-beta inhibited cartilage hypertrophy, growth of the bone collar, and matrix mineralization. These data demonstrate that OP-1 and TGF-beta exhibit opposite effects on cartilage growth but similar effects on osteogenesis in embryonic mouse long bone cultures. Since both OP-1 and TGF-beta have been demonstrated in embryonic cartilage and bone, these results suggest that they act as autocrine or paracrine regulators of embryonic bone development.     

Recycling zinc oxide varistor blocks for electro‐active silicone composites

The recycling process toward the elimination of varistor wastes into new electro‐active silicon composites has been investigated. We studied the dependence of the E‐J characteristics on the aggregate content in the polymer matrix. Formulations with 40 vol.% metal oxide varistor aggregates in the 100‐200 μm range exhibit reliable nonlinear behavior with a switching voltage of 280±30 V/mm. The breakdown voltage of the composite decreases as both filler's diameter and filler's volume fraction increases in the 550‐220 V/mm and 440‐280 V/mm range, respectively. This paves the way for the valorization of varistors based zinc oxide (ZnO) ceramics.     

Byzantine gathering in networks

This paper investigates an open problem introduced in Dieudonné et al. (ACM Trans Algorithms 11(1):1, 2014). Two or more mobile agents start from nodes of a network and have to accomplish the task of gathering which consists in getting all together at the same node at the same time. An adversary chooses the initial nodes of the agents and assigns a different positive integer (called label) to each of them. Initially, each agent knows its label but does not know the labels of the other agents or their positions relative to its own. Agents move in synchronous rounds and can communicate with each other only when located at the same node. Up to f of the agents are Byzantine. A Byzantine agent can choose an arbitrary port when it moves, can convey arbitrary information to other agents and can change its label in every round, in particular by forging the label of another agent or by creating a completely new one. What is the minimum number \({\mathcal {M}}\) of good agents that guarantees deterministic gathering of all of them, with termination? We provide exact answers to this open problem by considering the case when the agents initially know the size of the network and the case when they do not. In the former case, we prove \({\mathcal {M}}=f+1\) while in the latter, we prove \({\mathcal {M}}=f+2\). More precisely, for networks of known size, we design a deterministic algorithm gathering all good agents in any network provided that the number of good agents is at least \(f+1\). For networks of unknown size, we also design a deterministic algorithm ensuring the gathering of all good agents in any network but provided that the number of good agents is at least \(f+2\). Both of our algorithms are optimal in terms of required number of good agents, as each of them perfectly matches the respective lower bound on \({\mathcal {M}}\) shown in Dieudonné et al. (2014), which is of \(f+1\) when the size of the network is known and of \(f+2\) when it is unknown. Perhaps surprisingly, our results highlight an interesting feature when put in perspective with known results concerning a relaxed variant of this problem in which the Byzantine agents cannot change their initial labels. Indeed under this variant \({\mathcal {M}}=1\) for networks of known size and \({\mathcal {M}}=f+2\) for networks of unknown size. Following this perspective, it turns out that when the size of the network is known, the ability for the Byzantine agents to change their labels significantly impacts the value of \({\mathcal {M}}\). However, the relevance for \({\mathcal {M}}\) of such an ability completely disappears in the most general case where the size of the network is unknown, as \({\mathcal {M}}=f+2\) regardless of whether Byzantine agents can change their labels or not.     

Trace element differentiation in ferruginous accumulation soil patterns under tropical rainforest of southern Cameroon,the role of climatic change

Regions under tropical rainforest cover, such as central Africa and Brazil are characterised by degradation and dismantling of old ferricrete structures. In southern Cameroon, these processes are relayed by present-day ferruginous accumulation soil facies, situated on the middle and the lower part of hill slopes. These facies become progressively harder towards the surface, containing from bottom to top, mainly kaolinite, kaolinite-goethite and Al-rich goethite-hematite, and are discontinuous to the relictic hematite-dominated ferricrete that exist in the upper part of the hill slope. These features were investigated in terms of geochemical differentiation of trace elements. It appears that, in contrast to the old ferricrete facies, the current ferruginous accumulations are enriched in transitional trace elements (V, Cr, Co, Y, Sc) and Pb, while alkali-earth elements are less differentiated. This recent chemical accumulation is controlled both by intense weathering of the granodiorite bedrock and by mobilisation of elements previously accumulated in the old ferricrete. The observed processes are clearly linked to the present-day humid climate with rising groundwater tables. They slowly replace the old ferricretes formed during Cretaceous time under more seasonal climatic conditions, representing an instructive case of continuos global change.