Investigating the Performance of Self-compacting Concrete Exposed to Hot Weather

This study investigates the behavior of concrete in a real environment with a temperature exceeding 35 °C in the shade. It focuses on the rheological behavior of self-compacting concrete (SCC) and its ability to maintain its self-compacting aspect over time, compared to ordinary concrete (C3). The research also examines the impact of limestone fillers on SCC's fluidity in hot climates. In the hardened state, the study emphasizes concrete durability against sulfate and acid attacks and their effects on its microstructure. Three types of concrete were studied such as SCC without addition (C1), SCC with 15% of limestone fillers (C2), and (C3), were tested in terms of fresh and hardened states, along with durability against acid and sulfate attacks. Results showed that SCC in a hot climate maintained its self-compacting properties up to 25 minutes after mixing. However, over time, the fluidity of SCC with limestone fillers decreased noticeably and faster. The aging of concrete exposed to sulfuric acid in a hot and dry climate for six months was more intense than with sodium sulfate

P2Y12 receptor modulation of ADP‐evoked intracellular Ca2+ signalling in THP‐1 human monocytic cells

Background and purpose: The Gi‐coupled, ADP‐activated P2Y12 receptor is well characterised as playing a key role in platelet activation via crosstalk with P2Y1 in ADP‐evoked intracellular Ca2+ response. There is limited knowledge on the role of P2Y12 in ADP‐evoked Ca2+ responses in other blood cells. Here we investigate the role of P2Y12 receptor activation in modulation of ADP‐evoked Ca2+ responses in human THP‐1 monocytic cells. Experimental approach: A combination of intracellular Ca2+ measurements, RT‐PCR, immunocytochemistry, leukocyte isolation and siRNA‐mediated gene knockdown were used to identify the role of P2Y12 receptor activation. Key results: ADP‐evoked intracellular Ca2+ responses (EC50 2.7 M) in THP‐1 cells were abolished by inhibition of phospholipase C (U73122) or sarco/endoplasmic reticulum Ca2+‐ATPase (thapsigargin). Loss of ADP‐evoked Ca2+ responses following treatment with MRS2578 (IC50 200 nM) revealed a major role for P2Y6 in mediating ADP‐evoked Ca2+ responses. ADP‐evoked responses were attenuated either with pertussis toxin treatment, or P2Y12 inhibition with two chemically distinct antagonists (ticagrelor, IC50 5.3 M; PSB‐0739, IC50 5.6 M). ADP‐evoked responses were suppressed following siRNA‐mediated P2Y12 gene knockdown. The inhibitory effects of P2Y12 antagonists were fully reversed following adenylate cyclase inhibition (SQ22536). P2Y12 receptor expression was confirmed in freshly isolated human CD14+ monocytes. Conclusion and implications: Taken together, these data suggest that P2Y12 activation positively regulates P2Y6‐mediated intracellular Ca2+ signalling through suppression of adenylate cyclase activity in human monocytic cells

Interleukin-1 and TRAF6-dependent activation of TAK1 in the absence of TAB2 and TAB3

Interleukin-1 (IL-1) signaling induces the formation of Lys63-linked ubiquitin (K63-Ub) chains, which are thought to activate the “master” protein kinase TAK1 by interacting with its TAB2 and TAB3 subunits. Here, we report that IL-1β can also activate the TAB1-TAK1 heterodimer present in TAB2/TAB3 double knock-out (DKO) IL-1 receptor-expressing cells. The IL-1β-dependent activation of the TAB1- TAK1 heterodimer in TAB2/3 DKO cells required the expression and E3 ligase activity of TRAF6 and was reduced by the siRNA knock-down of Ubc13, an E2 conjugating enzyme that directs the formation of K63-Ub chains. IL-1β signaling was restored to TAB1/2/3 triple KO cells by the re-expression of either TAB1 or TAB2, but not by a ubiquitin-binding-defective mutant of TAB2. We conclude that IL-1β can induce the activation of TAK1 in two ways, only one of which requires the binding of K63-Ub chains to TAB2/3. The early IL-1β-stimulated, TAK1-dependent activation of p38α MAP kinase and the canonical IKK complex, as well as the NF-κBdependent transcription of immediate early genes was similar in TAB2/3 DKO and TAB2/3-expressing cells. However, in contrast to TAB2/3-expressing cells, IL-1β signaling was transient in TAB2/3 DKO cells and the activation of JNK1, JNK2 and p38γ was greatly reduced at all times. These observations indicate a role for TAB2/3 in directing the TAK1-dependent activation of MAP kinase kinases that switch on JNK1/2 and p38γ MAP kinases. These observations and the transient activation of the TAB1-TAK1 heterodimer may explain why IL-1β-dependent IL-8 mRNA formation was abolished in TAB2/3 DKO cells

Role of the P2Y6 receptor of UDP in the modulation of murine dendritic cell functions and Th1 polarisation of the immune response

Numerous studies have demonstrated the role of uridine diphosphate (UDP) and its P2Y6 receptor in the inflammatory reaction and innate immunity. However, the importance of the P2Y6 receptor in the adaptive immune response remains unclear. In this study, we demonstrate that the P2Y6 receptor is functionally expressed in murine bone marrow dendritic cells (BMDC). UDP induced a Ca2+ transient in these cells that was decreased in P2Y6-deficient mice. UDP also increased the endocytosis of fluorescein isothiocyanate-dextran (FITC-dextran) and amplified the secretion of interleukin 12-p70 (IL-12p70) induced by CpG; these responses were abolished in P2Y6-deficient mice. In vivo experiments showed that the serum level of specific IgG2c after immunisation with ovalbumin was decreased in P2Y6-deficient mice, while the level of specific IgG1 was unchanged. These data suggest that the P2Y6-mediated effects of UDP on myeloid dendritic cells play a role in the in vivo Th1 skewing of the immune response

An easy-to-use colorimetric enzymatic test-system for organophosphorus insecticides detection in olive oil

International audienceImmobilization of a low amount of electric eel acetylcholinesterase on microtiter plates by bioencapsulation in a sol-gel composite led to the preparation of a simple colorimetric enzymatic-assay for pesticides detection in olive oil. This bioassay has been used to carry out inhibition studies with three pesticides mainly used in the treatment of olive trees: Malaoxon, Methidathion-oxon and Omethoate, and tested using standard solutions and real samples of olive oil. The developed bio-tools showed a good reproducibility and stability as well as good analytical performances with limits of detection at least 10 times less than the maximum residue limit tolerated by international regulations. The obtained LODs were as low as 10-9 M for the widely used pesticide Malaoxon, 10-8 M for Methidathion oxon and 10-7 M for Omethoate. The developed test was designed for fast detection of the three target insecticides in such a complex matrix as olive oil without a laborious pre-treatment and after a simple liquid-liquid extraction, which demonstrate the potentiality of this technique to be used for commercial purpose

Enzymatic biosensor associated with Molecularly Imprinted Polymers for sensitive and selective detection of organophosphorus insecticides in olive oil

International audience5 different bio-tools have been developed for sensitive detection of three organophosphorus insecticides mainly used for the treatment of olive trees: Malaoxon, Omethoate and Methidathion-oxon. The systems are based on the immobilization of electric eel acetylcholinesterase on screen-printed electrode (SPE) and microtiter plates by 3 different methods of immobilization. These developed systems were optimized with laboratory samples and then tested on natural samples of olive oil after a simple liquid-liquid extraction. Among these five systems designed, the amperometric biosensor based on acetylcholinesterase immobilized by bioencapsulation in a sol-gel matrix presented the best performance in terms of operational stability, storage stability, reproducibility, and it proved to be best suited for the determination of insecticides in real samples of olive oil. This biosensor has been associated with a highly selective extraction method based on the use of Molecularly Imprinted Polymers (MIPs) to improve selectivity. The results showed that the association MIPs-biosensor can selectively detect and quantify the three organophosphorus insecticides in such a complex matrix as olive oil, with limits of detection much lower than the maximum residue limit tolerated by international regulations

The role of hybrid ubiquitin chains in the MyD88 and other innate immune signalling pathways

The adaptor protein MyD88 is required for signal transmission by Toll-like Receptors (TLRs) and receptors of the interleukin 1 (IL-1) family of cytokines. MyD88 signalling triggers the formation of Lys63-linked and Met1-linked ubiquitin (K63-Ub, M1-Ub) chains within minutes. The K63-Ub chains, which are formed by the E3 ubiquitin ligases TRAF6, Pellino1 and Pellino2, activate TAK1, the master kinase that switches on mitogen-activated protein (MAP) kinase cascades and initiates activation of the canonical IκB kinase (IKK) complex. The M1-Ub chains, which are formed by the Linear Ubiquitin chain Assembly Complex (LUBAC), bind to the NEMO component of the IKK complex and are required for TAK1 to activate IKKs, but not MAP kinases. An essential E3 ligase-independent role of TRAF6 is to recruit LUBAC into the MyD88 signalling complex, where it recognises preformed K63-Ub chains attached to protein components of these complexes, such as IRAK1, producing ubiquitin chains containing both types of linkage, termed K63/M1-Ub hybrids. The formation of K63/M1-Ub hybrids, which is a feature of several innate immune signalling pathways, permits the co-recruitment of proteins that interact with either K63-Ub or M1-Ub chains. Two likely roles for K63/M1- Ub hybrids are to facilitate the TAK1-dependent activation of the IKK complex and to prevent the hyper-activation of these kinases by recruiting A20 and A20-binding inhibitor of NF-κB1 (ABIN1). These proteins restrict activation of the TAK1 and IKK complexes, probably by competing with them for binding to K63/M1-Ub hybrids. The formation of K63/M1-Ub hybrids may also regulate the rate at which the ubiquitin linkages in these chains are hydrolysed. The IKK-catalysed phosphorylation of some of its substrates permits their recognition by the E3 ligase SCFβ TRCP, leading to their Lys48-linked ubiquitylation and proteasomal degradation. Innate immune signalling is therefore controlled by the formation and destruction of three different types of ubiquitin linkage

Purinergic signalling links mechanical breath profile and alveolar mechanics with the pro-inflammatory innate immune response causing ventilation-induced lung injury

Severe pulmonary infection or vigorous cyclic deformation of the alveolar epithelial type I (AT I) cells by mechanical ventilation leads to massive extracellular ATP release. High levels of extracellular ATP saturate the ATP hydrolysis enzymes CD39 and CD73 resulting in persistent high ATP levels despite the conversion to adenosine. Above a certain level, extracellular ATP molecules act as danger-associated molecular patterns (DAMPs) and activate the pro-inflammatory response of the innate immunity through purinergic receptors on the surface of the immune cells. This results in lung tissue inflammation, capillary leakage, interstitial and alveolar oedema and lung injury reducing the production of surfactant by the damaged AT II cells and deactivating the surfactant function by the concomitant extravasated serum proteins through capillary leakage followed by a substantial increase in alveolar surface tension and alveolar collapse. The resulting inhomogeneous ventilation of the lungs is an important mechanism in the development of ventilation-induced lung injury. The high levels of extracellular ATP and the upregulation of ecto-enzymes and soluble enzymes that hydrolyse ATP to adenosine (CD39 and CD73) increase the extracellular adenosine levels that inhibit the innate and adaptive immune responses rendering the host susceptible to infection by invading microorganisms. Moreover, high levels of extracellular adenosine increase the expression, the production and the activation of pro-fibrotic proteins (such as TGF-β, α-SMA, etc.) followed by the establishment of lung fibrosis