The calcium transient is central in the ECC in muscle fibers. It results from the neuronal action potential transmitted to the fibers via the neuromuscular junction, and it triggers sarcomere shortening. Interestingly, we found that amplitude and kinetics characteristics of the calcium transient are normal in HTZ EDL muscles which develop a weaker force. This result suggests that contractile property impairment is probably not directly due to the calcium defect in affected EDL muscle. This apparently diverges from recent report of defective ECC in zebrafish expressing the p.S619L DNM2 mutant (Gibbs et al., 2014). These discrepancies might be due to the difference in muscles studied or overexpression of a DNM2 mutant linked to the severe form of the disease in a developing muscle (Gibbs et al., 2014) versus endogenous expression of a DNM2 mutant linked to a milder form of AD-CNM in an adult muscle (the present study). Characterization of the calciumhomeostasis in additional muscles and in animal models expressing additional DNM2 mutations will be useful to better establish a potential relationship between the type of calcium defect and clinical severity in DNM2-related CNM.
Healthy cells continually produce low levels of reactive oxygen species (ROS), which are buffered by multiple antioxidant systems. Imbalance between ROS production and elimination results in oxidative stress, which has been implicated in aging and in numerous human diseases, including cancer and diabetes. Selenoproteins are a family of proteins that contain the amino acid selenocysteine, encoded by an in-frame UGA. Those selenopro- teins whose function is identified are catalytically active in redox processes, representing one of the main enzymatic antioxidant systems and important mediators of the beneficial role of selenium in human health. Nevertheless, the function of most selenoproteins remains unknown; this included Selenoprotein N (SelN), the only selenoprotein directly associated with a human genetic disease. Mutations of the SelN gene cause SEPN1- related myopathy, a particular early-onset muscle disorder. Recent studies have identified SelN as a key protein in cell protection against oxidative stress and redox-related calciumhomeostasis. Furthermore, an effective ex vivo treatment of SelN deficiency has been identified, paving the way to a clinical therapy. In this review we discuss the physiological and pathophysiological role of SelN and the interest of SEPN1-related myopathy as a model paradigm to understand and target therapeutically other selenoproteins involved in human health and disease. Antioxid. Redox Signal. 12, 893–904.
Mutations in the polycystins cause autosomal dominant polycystic kidney disease (ADPKD). Here we show that transmembrane protein 33 (TMEM33) interacts with the ion channel polycystin-2 (PC2) at the endoplasmic reticulum (ER) membrane, enhancing its opening over the whole physiological calcium range in ER liposomes fused to planar bilayers. Consequently, TMEM33 reduces intracellular calcium content in a PC2-dependent manner, impairs lyso- somal calcium re ﬁlling, causes cathepsins translocation, inhibition of autophagic ﬂux upon ER stress, as well as sensitization to apoptosis. Invalidation of TMEM33 in the mouse exerts a potent protection against renal ER stress. By contrast, TMEM33 does not in ﬂuence pkd2- dependent renal cystogenesis in the zebra ﬁsh. Together, our results identify a key role for TMEM33 in the regulation of intracellular calciumhomeostasis of renal proximal convoluted tubule cells and establish a causal link between TMEM33 and acute kidney injury.
collecting duct [ 69 ]. Integrating this detailed model into our global model of calciumhomeostasis
would be a logical next step.
The modeling approach chosen for the bone compartment could also be improved. Indeed, in the current version of the model, the resorption rate does not depend on the quantity of bone calcium and phosphate. Until now, it was not a problem since we were not interested in the evolution of bone mass, but were focusing instead on the rapidly exchangeable pool. Yet, if we want to simulate bone mass diseases such as osteoporosis as well as osteopetrosis, we should take this into consideration. Additionally, the formation/dissociation of calcium and phosphate complexes in the deep bone is not modeled and should be considered in the future. Moreover, in section 5.1.3, we assumed that there is no exchange of calcium-phosphate complexes between plasma and bone. The reason for this assumption is the absence of parameters for these fluxes. These exchanges should be included in a further version of the model when experimental data are available.
During a lytic infection, Herpes Simplex Virus type 1 (HSV-1) must go through multiple steps of fusion to replicate and propagate properly. For this purpose, the virus has evolved consequently by taking advantage of the cellular machinery using host factors and proteins. In the literature, processes underlying HSV-1’s entry have been extensively elucidated. However, it remains unclear how newly synthesized viral particles egress from the host cell, and what cellular factors are implicated in this process. Results published by our laboratory suggest that the cellular protein, Extended Synaptotagmin 1 (E-Syt1), has a negative and global impact on the viral propagation when down regulated by RNA interference. Consequently, this study aims to confirm and deepen our understanding of E-Syt1’s role on HSV-1, particularly during viral egress. Since activation of E-Syt1 is linked to the increase in cytoplasmic calcium concentration, we also investigated calcium involvement during later stages of viral propagation. Interestingly, overexpression of E-Syt1 had no measurable effect on HSV-1 propagation whereas calcium has a dual effect on viral propagation. While early calcium sequestering (4 and 6 hours post- infection) using chelators represses viral egress, no significant effect was detected when chelators were added at later time points (12 and 16 hours post-infection). Our results give interesting insights on how HSV-1 relies on intracellular calciumhomeostasis to properly mediate viral egress. These results may lead to the discovery of new mechanisms or cellular proteins that are regulated by calcium and hijacked by HSV-1 during lytic replication.
Muscle morphometric and phenotypic changes following chronic treatment with clenbuterol
To investigate the effect on muscle Ca 2+ homeostasis of chronic clenbuterol treatment, 22 male Wistar rats received clenbuterol (CBL) or saline vehicle (CTL) for 21 days and then the EDL muscles were harvested for morphological and functional inves- tigations. As previously described , chronic CBL administration resulted in a significant increase of the EDL muscle mass compared to controls (+22%; 220.965.4 mg CBL vs 176.368.3 CTL group; p,0.001; n = 11 rats/group). Muscle fiber types were identified based on the extent of myosin ATPase staining (Fig. 1A). As seen in Fig. 1B, CBL treatment led to an increase in the CSA of type I (+20%), type IIa (+17%) and type IIx-IIb (+72%) fibers. Fig. 1C shows that CBL treatment led to a shift from a slow- oxidative to a fast-glycolytic fiber type profile. While the percentage of type I fibers did not change significantly, a 17% decrease in type IIa fibers and a 15% increase in type IIx-IIb fibers were observed (p,0.05).
role for ANO5 in ER-mediated [Ca 2 + ] c homeostasis.
Consistent with this we ﬁnd that controlling injury- triggered [Ca 2 + ] c increase improves PMR in the patient
cells. ANO5 is proposed to have both ion channel and phospholipid scramblase activities 19 , 21 , 28 , but this remains to be veri ﬁed by direct assay of puriﬁed ANO5 in a reconstituted system. Interestingly, our 3D structural model of ANO5 places a number of disease-linked mutations close to the site at which activating Ca 2+ ions bind the protein, and also in the vicinity of the SCRD and the lumenal entryway to the ion/lipid transport pathway (Fig. 4 a, h). Our studies show that restoring the Ca 2+ homeostasis is more important for the health of the patient muscle cells, while the relevance of the proposed scramblase function remains unclear.
In a previous communication , we described the formation of a composite material based on hydroxylapatite inserted in a calcium sulfate porous hybrid material, herein named composite. It was found that hydroxylapatite could be incorporated up to 30% by weight without significant deterioration of the mechanical strength of the composite and that the porosity was sufficient to allow for fluid flow. Calcium sulfate and phosphate composites have been reported before  and found to have good water resistance. Such composites have been described for use as resorbable biomaterials in bone surgery , but have never been used for the retention of heavy metals from polluted waters. Here, our objective was to test the composite for heavy metal uptake and compare the result with the well-known capacity of pure apatites to sorb metal ions. The composite materials were tested both in batch mode and in a column continuous flow-through mode.
[ 15 , 20 , 21 ]. The presented assays had to be considered as preliminary results to check the maintenance of known efficiency when silver is incorporated in calcium carbon- ate–calcium phosphate bone cement. Antimicrobial assays were performed in conditions allowing biofilm formation but not planktonic growth, because such adherent bacteria are significantly more resistant to immune system and antibiotics treatments. In addition, these conditions are more representative of the pathologic situation since bio- film formation is required to induce chronic bones infec- tions [ 38 ]. Pellets including the tested silver amount displayed some strong anti-adhesive and/or anti-biofilm formation exerted by silver associated with a CaCO 3 –CaP
Additionally, the model was able to predict the spatial- temporal degradation and dissolution of the scaffolds
(Fig. 5 a–f). This spatial information represents one of the
clear added values of computational modelling in the con- text of designing new biomaterials. No measurement devices exist to date that allow this spatial representation of the local calcium concentration—even though these local concentra- tions are what is felt by the cells seeded onto the scaffold. Computational models therefore allow to link the insight
Calcium chloride is soluble in either cold or hot water. In making a solution it is good practice to add the salt to the water, for if water is added to the salt a hard coating forms, making dissolution slow. Freshly made, the solution is warm and should be cooled before use.
Very concentrated solutions of calcium chloride are not prepared because of the possibility that excess chloride will settle to the bottom. It is more convenient to prepare a solution containing 4 pounds of regular flake form (with 77 per cent minimum calcium chloride) or 3¼ pounds of pellet or concentrated flake or other granulated form (with 94 per cent minimum calcium chloride) in each gallon of solution. It then becomes practical, though not exact, to add 1 quart of standard solution per sack of cement when 1 per cent calcium chloride is specified or 2 quarts per sack for 2 per cent calcium chloride. The solution is considered to be a part of the mixing water for concrete. For example, for a 5-sack, 5-cubic yard mix (5 sacks per cubic yard) requiring 2 per cent calcium chloride and 150 gallons of mixing water, the chloride solution would account for 12.5 gallons and the water for 137.5 gallons.
Figure 2. Rôle hypothétique du calcium dans la chaîne de transduction contrôlant la phosphorylation de la PEPC dans les cellules du mésophylle. 1. Dès l’illumination, l’alcalinisation du cytosol (due au trans- port du 3-APG dans les chloroplastes ; non montré) est détectée par microscopie confocale. 2. Elle est suivie par une entrée de calcium externe contribuant à l’activation de la PI-PLC (PLC). 3. L’inositol 1,4,5 trisphosphate (Ins (1,4,5)P 3 provoque l’ouverture de canaux calciques du tonoplaste, ce qui amplifie la
In Rag2 −/− x γc −/− , Rag2 −/− x Rorc GFP/GFP , and Ltb flox/flox x Cd19- Cre x Rorc-Cre mice, residual numbers of Sirpα + CD4 + Esam +
Figure 3. Rorgt + ILC3s nonredundantly control the homeostasis of Sirpα + CD4 + Esam + cDC2s. (A) Representative immunofluorescence image of WT splenic cDCs and ILCs. Spleen sections were stained with the indicated markers allowing identification of the different cDC and ILC subsets. CD11c + voxels were used to mask cDC-specific markers as shown in the middle panel. ILC subsets were identified based on the expression of Eomes, Gata3, NK1.1, and Rorgt. Note also the presence, in the right panel, of Eomes + NK1.1 − cells that most likely represent regulatory T cells. n = 3 spleens. Scale bars, 200 µm for low-magnification images, 100 µm for insets. (B) Schematic representation of cDC and ILC subset distribution in the spleen shown in A. (C) Spatial frequency distribution of WT cDCs around Rorgt + ILC3s for the spleen shown in A. The numbers on the plot reflect the percentage of cDCs from each subset present in a 25-µm radius from Rorgt + ILC3s. Bottom: Summary of median nearest neighbor distance for the three spleens analyzed. Repeated-measures ANOVA with Tukey ’s multiple comparisons post-test. (D) Probability of observing a cDC of a given subset as a function of spatial distance from Rorgt + ILC3s in the spleen shown in A. The observed probability is shown in bold. The result of randomly relabeling Rorgt + ILC3s across the ILC repertoire is show in gray (n = 39). The upper and lower boundary values for those simulations are depicted by the dotted lines. (E) Representative flow cytometry plots and quantification of splenic cDCs in Rorc +/+ , Rorc GFP/+ , and Rorc GFP/GFP mice. n = 7 Rorc +/+ mice, 8 Rorc GFP/+ mice, and 8 Rorc GFP/GFP mice; two independent experiments; two-way ANOVA with Sidak ’s multiple comparisons post-test. (F) Representative flow cytometry plots and quantification of splenic cDCs in Rag2 −/− x Rorc +/+ , Rag2 −/− x Rorc GFP/+ and Rag2 −/− x Rorc GFP/GFP mice. n = 10 Rag2 −/− x Rorc +/+ mice, 11 Rag2 −/− x Rorc GFP/+ mice, and 7 Rag2 −/− x Rorc GFP/GFP mice; three independent experiments; two-way ANOVA with Sidak ’s multiple comparisons post-test. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.
The first self-setting calcium phosphate cements (CPC) were introduced in the early 1980s as biomaterials for bone repair and regeneration [ 1 ]. Since then, different CPCs have been developed; their biomimetism and their excel- lent osteoconductivity make them interesting candidates for dental or orthopaedic applications. On the other hand, their moulding ability allows for the optimal filling of bone. Thus, many studies have been performed in order to improve their physico-chemical properties and their bio- logical behaviour. Nevertheless, some important issues still need to be overcome. Among them, improved resorption capability and better protection against implant-associated infections are major challenges in this field [ 2 , 3 ].
machinery suggests that Ca 2+ signalling in the nucleus can be independent of cytosolic variations even if the mechanisms involved are not yet clearly established. On the other hand, the global cytosolic Ca 2+ signals can be easily transmitted to the nucleoplasm through the NPCs, which are freely permeable to small molecules like calcium ions. The exchanges between the cytoplasm and the nucleoplasm depend on the area of exchange and the number of NPCs and these two features are increased in some cell types and under some physiological conditions by the formation of invaginations of the NE. These structures, recently called nucleoplasmic reticulum, have long been observed, but very interesting recent data suggest that they could play important roles in nuclear functions. The nucleoplasmic reticulum allows the delivery of Ca 2+ locally deep inside the nucleus. It also forms separate compartments of varying sizes within the nucleoplasm and could therefore determine whether the nucleus functions as an integrator or a detector of oscillating Ca 2+ signals (Queisser, et al., 2011). Until now we have described the generation of Ca 2+ microdomains by considering their different subcellular location and how each organelle has its own distinct Ca 2+ -handling properties. A future challenge will be to characterise the signalling pathways and/or the physiological conditions that regulate the formation of the nucleoplasmic reticulum and modify the geometry of the nucleus. These regulatory mechanisms more likely participate in the pattern of the Ca 2+ signal and possibly in other nuclear processes. The morphology
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Interaction of calcium lignosulfonate with tricalcium silicate, hydrated tricalcium silicate, and calcium hydroxide
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Differential thermal method of estimating calcium hydroxide in calcium silicate and cement pastes