Various Concentrations Of Calcium Research Articles

Effect of Calcium Supplementation and TMEM16A Inhibition on Endoplasmic Reticulum Stress Induced by Dental Fluorosis in Mice.

Dental fluorosis is a discoloration of the teeth caused by the excessive consumption of fluoride. It represents a distinct manifestation of chronic fluorosis in dental tissues, exerting adverse effects on the human body, particularly on teeth. The transmembrane protein 16a (TMEM16A) is expressed at the junction of the endoplasmic reticulum and the plasma membrane. Alterations in its channel activity can disrupt endoplasmic reticulum calcium homeostasis and intracellular calcium ion concentration, thereby inducing endoplasmic reticulum stress (ERS). This study aims to investigate the influence of calcium supplements and TMEM16A on ERS in dental fluorosis. C57BL/6 mice exhibiting dental fluorosis were subjected to an eight-week treatment with varying calcium concentrations: low (0.071%), medium (0.79%), and high (6.61%). Various assays, including Hematoxylin and Eosin (HE) staining, immunohistochemistry, real-time fluorescence quantitative polymerase chain reaction (qPCR), and Western blot, were employed to assess the impact of calcium supplements on fluoride content, ameloblast morphology, TMEM16A expression, and endoplasmic reticulum stress-related proteins (calreticulin (CRT), glucose-regulated protein 78 (GRP78), inositol requiring kinase 1α (IRE1α), PKR-like ER kinase (PERK), activating transcription factor 6 (ATF6)) in the incisors of mice affected by dental fluorosis. Furthermore, mice with dental fluorosis were treated with the TMEM16A inhibitor T16Ainh-A01 along with a medium-dose calcium to investigate the influence of TMEM16A on fluoride content, ameloblast morphology, and endoplasmic reticulum stress-related proteins in the context of mouse incisor fluorosis. In comparison to the model mice, the fluoride content in incisors significantly decreased following calcium supplements (p < 0.01). Moreover, the expression of TMEM16A, CRT, GRP78, IRE1α, PERK, and ATF6 were also exhibited a substantial reduction (p < 0.01), with the most pronounced effect observed in the medium-dose calcium group. Additionally, the fluoride content (p < 0.05) and the expression of CRT, GRP78, IRE1α, PERK, and ATF6 (p < 0.01) were further diminished following concurrent treatment with the TMEM16A inhibitor T16Ainh-A01 and a medium dose of calcium. The supplementation of calcium or the inhibition of TMEM16A expression appears to mitigate the detrimental effects of fluorosis by suppressing endoplasmic reticulum stress. These findings hold implications for identifying potential therapeutic targets in addressing dental fluorosis.

Aluminum Supplementation Mediates the Changes in Tea Plant Growth and Metabolism in Response to Calcium Stress.

Tea plants are more sensitive to variations in calcium concentration compared to other plants, whereas a moderate aluminum concentration facilitates the growth and development of tea plants. Aluminum and calcium show a competitive interaction with respect to the uptake of elements, consequently exerting physiological effects on plants. To further explore these interactions, in this study, we used the solution culture method to treat tea plants with two calcium concentrations (0.8 mM and 5.6 mM) and three aluminum concentrations (0 mM, 0.4 mM, and 1 mM). We then determined the influence of the combined treatments on root growth and quality compound accumulation in the tissues by a combination of phenotype, gene expression, and metabolite analyses. Moderate aluminum supplementation (0.4 mM) alleviated the inhibition of root growth caused by high calcium stress. High calcium stress significantly inhibited the accumulation of most amino acids (e.g., Glutamic acid, Citulline, and Arginine) and organic acids (e.g., a-ketoglutaric acid) in the roots, stems, and leaves, whereas aluminum deficiency significantly increased most amino acids in the roots and leaves (except Serine, Alanine, and Phenylalanine in the roots and Ser in the leaves), with a more than two-fold increase in Arg and Lysine. High calcium stress also induced the accumulation of secondary metabolites such as epigallocatechin gallate and procyanidin in the roots, whereas aluminum supplementation significantly reduced the contents of flavonol glycosides such as quercetin, rutin, myricitrin, and kaempferitrin, as well as caffeine, regardless of calcium concentration. Aluminum supplementation reversed some of the changes in the contents of leaf metabolites induced by calcium stress (e.g., 4-dihydroquercetin, apigenin C-pentoside, phenethylamine, and caffeine). Overall, calcium stress caused severe growth inhibition and metabolic disorders in tea plants, which could be reversed by aluminum supplementation, particularly in maintaining the root tips and the accumulation of secondary metabolites. These results provide a theoretical basis for improving calcium-aluminum nutrient management to promote tea plant growth and quality.

Investigation of calcium substitution on magnetic and dielectric properties of Mg–Zn nano ferrites

In this work, an efficient, cost-effective, and less time-consuming citrate precursor wet chemical approach was employed to prepare a series of Calcium (Ca) doped Magnesium–Zinc ferrite of composition Mg0.4Zn0.6-xCax Fe2O4 (0.0 ≤ x ≤ 0.6). X-ray diffraction (XRD), Scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX) analysis confirmed the spinel structure and nanometric size of the particles. Williamson-Hall (W–H) plots were drawn by making use of XRD data and calculated values of lattice strain were found in the range (3.00 × 10−3 to 9.09 × 10−3) for various concentrations of calcium. The cubic spinel structure of produced ferrites was also verified by three active Raman modes (A1g, Eg, and T2g). In the Vibrating sample magnetometer (VSM) study, an “S” shape curve shows the low values of coercivity for all the samples in the range 59–105 Oe. For all Ca concentrations, the dielectric loss tangent values were evaluated to be extremely low 0.03 to 0.18 at 1 MHz frequency. The highly magnetic nature and very low value of loss factor make this prepared nanoferrite material best suited for the manufacturing of high-frequency application devices.

Roles of Calcium Signaling in Gene Expression and Photosynthetic Acclimatization of Solanum lycopersicum Micro-Tom (MT) after Mechanical Damage.

A momentary increase in cytoplasmic Ca2+ generates an oscillation responsible for the activation of proteins, such as calmodulin and kinases, which interact with reactive oxygen species (ROS) for the transmission of a stress signal. This study investigated the influence of variations in calcium concentrations on plant defense signaling and photosynthetic acclimatization after mechanical damage. Solanum lycopersicum Micro-Tom was grown with 0, 2 and 4 mM Ca2+, with and without mechanical damage. The expression of stress genes was evaluated, along with levels of antioxidant enzymes, hydrogen peroxide, lipid peroxidation, histochemistry, photosynthesis and dry mass of organs. The ROS production generated by mechanical damage was further enhanced by calcium-free conditions due to the inactivation of the oxygen evolution complex, contributing to an increase in reactive species. The results indicated that ROS affected mechanical damage signaling because calcium-free plants exhibited high levels of H2O2 and enhanced expression of kinase and RBOH1 genes, necessary conditions for an efficient response to stress. We conclude that the plants without calcium supply recognized mechanical damage but did not survive. The highest expression of the RBOH1 gene and the accumulation of H2O2 in these plants signaled cell death. Plants grown in the presence of calcium showed higher expression of SlCaM2 and control of H2O2 concentration, thus overcoming the stress caused by mechanical damage, with photosynthetic acclimatization and without damage to dry mass production.

Modeling Calcium Signaling in S. cerevisiae Highlights the Role and Regulation of the Calmodulin-Calcineurin Pathway in Response to Hypotonic Shock

Calcium homeostasis and signaling processes in Saccharomyces cerevisiae, as well as in any eukaryotic organism, depend on various transporters and channels located on both the plasma and intracellular membranes. The activity of these proteins is regulated by a number of feedback mechanisms that act through the calmodulin-calcineurin pathway. When exposed to hypotonic shock (HTS), yeast cells respond with an increased cytosolic calcium transient, which seems to be conditioned by the opening of stretch-activated channels. To better understand the role of each channel and transporter involved in the generation and recovery of the calcium transient—and of their feedback regulations—we defined and analyzed a mathematical model of the calcium signaling response to HTS in yeast cells. The model was validated by comparing the simulation outcomes with calcium concentration variations before and during the HTS response, which were observed experimentally in both wild-type and mutant strains. Our results show that calcium normally enters the cell through the High Affinity Calcium influx System and mechanosensitive channels. The increase of the plasma membrane tension, caused by HTS, boosts the opening probability of mechanosensitive channels. This event causes a sudden calcium pulse that is rapidly dissipated by the activity of the vacuolar transporter Pmc1. According to model simulations, the role of another vacuolar transporter, Vcx1, is instead marginal, unless calcineurin is inhibited or removed. Our results also suggest that the mechanosensitive channels are subject to a calcium-dependent feedback inhibition, possibly involving calmodulin. Noteworthy, the model predictions are in accordance with literature results concerning some aspects of calcium homeostasis and signaling that were not specifically addressed within the model itself, suggesting that it actually depicts all the main cellular components and interactions that constitute the HTS calcium pathway, and thus can correctly reproduce the shaping of the calcium signature by calmodulin- and calcineurin-dependent complex regulations. The model predictions also allowed to provide an interpretation of different regulatory schemes involved in calcium handling in both wild-type and mutants yeast strains. The model could be easily extended to represent different calcium signals in other eukaryotic cells.

Electrophysiological and Morphological Studies of SOD1 Transgenic Mice: An Animal Model of ALS

Amyotrophic lateral sclerosis (ALS) is a disease where upper and lower motor neurons die, and it is often associated with mutations of superoxide dismutase 1 (SOD1). We have used mouse models to compare physiologic and morphologic characteristics of cervical motor neurons in wild-type and mutant animals. Slices of the cervical spinal cord were prepared from old wild-type and mutant G93A and G85R mice, and intracellular recordings of membrane potential, resistance and responses to application of excitatory neurotransmitters were studied. Some motor neurons were injected with Lucifer Yellow for morphological analysis. There were no significant differences between membrane potential in the SOD1 mutants and aged wild-type mice, but membrane resistance was somewhat higher in the mutant motor neurons. Dendrites of the mutant motor neurons were not responsive to ionophoretic application of excitatory amino acids, although the cell body responded strongly. In Lucifer-filled cells, the dendrites were found to disappear. Mutant motor neurons were sometimes spontaneously active. Responses of mutant motor neurons to perfused glutamate with varying calcium concentrations in the Ringer’s solution were different from those of the wild-type cells.

Searching for alternative toxicology testing systems: The response of isolated mitochondria from Saccharomyces cerevisiae, potato tuber, and mouse liver to a toxic insult

Mitochondria are cellular power plants known as essential organelles for energy (ATP) metabolism. However, today it is evident that various vital compounds are partially or exclusively synthesized in mitochondria. Moreover, this organelle plays a pivotal role in essential processes such as cell death. The isolated mitochondrion is an excellent experimental model for evaluating the role of mitochondria in the pathogenesis of diseases. Various in vitro and in vivo experimental models have been developed to study mitochondria. On the other hand, some alternative models could also help decrease the use of animal models. In the current study, we compared the response of mitochondria isolated from mouse liver, saccharomyces cerevisiae (S.c), and potato tuber to various concentrations of calcium (Ca2+) as a robust mitochondrial disturbing agent. The current study found that significant mitochondrial depolarization, decreased ATP levels, mitochondrial permeabilization, and decreased mitochondrial dehydrogenases activity were found in all isolated mitochondrial preparations. No significant difference between mouse liver, S.c, and potato tuber mitochondria were detected in experiments carried out in the current investigation. We are aware that mitochondria from different species have a huge structural and enzymatic variance. Hence, these models could just estimate the effect of xenobiotics in biological systems. However, the data derived from this study could finally help to decrease the use of experimental animals and provide new approaches for evaluating mitochondrial function.

Experience of application of calcium-containing cored wire with various fillers at steel ladle treatment

Treatment of mass production steels by cored calcium-containing wires is widely spread all over the world. Injection of several tens of gram of calcium per 1 t of the treated steel enables significantly improve its cast ability, increase the yield of CC billet, decrease rejection of rolled products by surface and internal defects, improve corrosion properties of steel and have similar effects. At the same time application of the technological method requires accurate forecasting of the purpose process conditions, strict following the technology parameters, application of quality injection equipment, as well as application of best calcium-containing cored wires. Taking into consideration, that the role of the filler in the cored wires is not discussed widely, the purpose of the work was summarizing of the experience of application of various calcium-containing materials. Mechanisms of calcium influence on steel quality considered. It was shown that it is possible to control not only chemical composition but also phase composition of nonmetallic inclusions by variation of calcium concentration in steel melt. Among others, liquid inclusions based on calcium aluminates which have high speed of surfacing, will be formed, thus ensuring deep steel refining for nonmetallic inclusions within a short time. Having high sulphur affinity, at the stage of continuous casting calcium forms sulfide and oxide-sulfide nonmetallic inclusions of micron and submicron size, uniformly distributed in the steel volume, which improves the structure of center zone of the continuously casted billet and that of the rolled product. It was shown that calcium-containing filler of a cored wire plays an important role in ensuring high and stable result. It was established based on the probes from tundish that the average recovery of fillers of electrolytic calcium is higher comparing with other fillers. Analysis of frequency distribution of the calcium recovery value showed that to ensure a guaranteed minimal content of calcium of 12 ppm at a CCM, it is required to inject aluminothermic calcium in the amount of 4.5 times bigger comparing with electrolytic calcium and ferrocalcium – 6 times bigger. Analysis of cast ability of steel treated by cored wires showed that to ensure a stable cast ability it is enough to add 55 grams of electrolytic calcium per 1 t of steel, at that addition of 83 grams of aluminothermic calcium does not ensure a stable casting from heat to heat. A dependence of rolled products rejection indices on calcium content in steel was noted, which indicated of a possibility of further increase of economic efficiency of technologies of steel mass production due to development of steel treatment by calcium.

A Novel Method to Measure Myofibril Strain in Intact Human Stem Cell Derived Cardiomyocytes

Currently the state of the art method for measuring strain in individual muscle myofibrils is to isolate them for attachment to microtools that act as force measuring cantilevers and length controllers. However, this reductionist approach omits the physical and native context that could influence the force generating properties of myofibrils and myocytes, including crowding of other organelles, the microtubular network, and connection to the matrix and other cells via adhesion complexes. To study calcium dependent strain of native myofibril networks in intact human cardiomyocytes, we are developing a system to induce activation and contraction of live human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) through treatment with gentle detergent and buffers of varying calcium concentration.

Calcium-Mediated Interactions Regulate the Subcellular Localization of Extracellular Signal-Regulated Kinases (ERKs).

The subcellular localization of ERK1 and ERK2 (ERKs) in cells, which is important for proper signaling, may be regulated through protein-protein interactions. However, the proteins involved and the way they are regulated to affect localization is not entirely understood. In order to identify the interacting proteins upon varying conditions, we used co-immunoprecipitation of ERK, active ERK and its binding CRS mutant. In addition, we examined the effect of intracellular calcium on the binding using calcium chelators and ionophores, analyzing the binding using silver stain, mass spectrometry and immunoblotting. The effect of calcium on ERK localization was examined using immunofluorescent staining and Western blotting. We found that inactive ERK2 interacts with a large number of proteins through its CRS/CD domain, whereas the phospho-ERK2 interacts with only few substrates. Varying calcium concentrations significantly modified the repertoire of ERK2-interacting proteins, of which many were identified. The effect of calcium on ERKs' interactions influenced also the localization of ERKs, as calcium chelators enhanced nuclear translocation, while elevated calcium levels prevented it. This effect of calcium was also apparent upon the physiological lysophosphatidic acid stimulation, where ERKs translocation was delayed compared to that induced by EGF in a calcium-dependent manner. In vitro translocation assay revealed that high calcium concentrations affect ERKs' translocation by preventing the shuttling machinery through the nuclear envelope, probably due to higher binding to nuclear pore proteins such as NUP153. These results are consistent with a model in which ERKs in quiescent cells are bound to several cytoplasmic proteins. Upon stimulation, ERKs are phosphorylated and released from their cytoplasmic anchors to allow shuttling into the nucleus. This translocation is delayed when calcium levels are increased, and this modifies the localization of ERKs and therefore also their spatiotemporal regulation. Thus, calcium regulates ERKs localization, which is important for the compartmentalization of ERKs with their proper substrates, and thereby their signaling specificity.

Monitoring calcium-induced epidermal differentiation in vitro using multiphoton microscopy.

.Significance: Research in tissue engineering and in vitro organ formation has recently intensified. To assess tissue morphology, the method of choice today is restricted primarily to histology. Thus novel tools are required to enable noninvasive, and preferably label-free, three-dimensional imaging that is more compatible with futuristic organ-on-a-chip models.Aim: We investigate the potential for using multiphoton microscopy (MPM) as a label-free in vitro approach to monitor calcium-induced epidermal differentiation.Approach: In vitro epidermis was cultured at the air–liquid interface in varying calcium concentrations. Morphology and tissue architecture were investigated using MPM based on visualizing cellular autofluorescence.Results: Distinct morphologies corresponding to epidermal differentiation were observed. In addition, -induced effects could be distinguished based on the architectural differences in stratification in the tissue cultures.Conclusions: Our study shows that MPM based on cellular autofluorescence enables visualization of -induced differentiation in epidermal skin models in vitro. The technique has potential to be further adapted as a noninvasive, label-free, and real-time tool to monitor tissue regeneration and organ formation in vitro.

Electrochemical detection of calcium and magnesium in water bodies

The design, fabrication, and implementation of novel flexible sensors for electrochemical detection of multiple minerals such as calcium and magnesium in water bodies are presented in this paper. 3D printing technique was utilized to form the master moulds for developing the sensor prototype. The 3D printed moulds were developed initially using Poly Lactic Acid as the printing filament. Multi-Walled Carbon Nanotubes and Polydimethylsiloxane were used for forming the electrodes and substrates of the sensor patches, respectively. The casting of Multi-Walled Carbon Nanotubes powder and Polydimethylsiloxane were done on the 3D printed moulds. The electrodes were patterned in an interdigitated manner to operate on the impedimetric principle. The passive elements of the equivalent circuit of the interdigitated sensors were determined using Complex Non-Linear Least-Square Curve Fitting software. The total change in impedance concerning differently concentrated solutions was due to different resistive and reactive elements of the sensors. The resistance, reactance, and impedance values from the sensor patches were analysed during the experiment for calcium and magnesium solutions. Experimental outcomes proved that the sensor was able to differentiate various concentrations of calcium and magnesium ions between 1 ppm and 200 ppm solutions. The reproducibility, repeatability, and reusability of the sensors were also tested to propose the developed sensors as an alternative solution for the determination of calcium and magnesium ions from unknown samples.

M-class hypertrophic cardiomyopathy cardiac actin mutations increase calcium sensitivity of regulated thin filaments

Hypertrophic cardiomyopathy is a commonly occurring cardiovascular disease resulting primarily from changes in proteins participating in muscle contraction in the heart, including the cardiac actin protein. Changes in cardiac actin located exclusively in the myosin binding site are called M-class variants and include the H88Y, R95C, and E99K substitutions and F90Δ deletion. The prevailing hypothesis for these mutations is that hypertrophic cardiomyopathy is the result of increased calcium sensitivity of contraction in the myocardium. To test this hypothesis, we studied the activity of myosin at varying calcium concentrations in the presence of regulated thin filaments containing M-class cardiac actin variants. We found that all M-class cardiac actin variants exhibit increased calcium sensitivity, with the R95C variant also displaying significant decreases in maximal myosin activity. This work represents the first characterization of all M-class variant proteins and suggests that drugs targeting contraction specifically to treat hypertrophic cardiomyopathy must consider the impact on both calcium sensitivity and maximal myosin activity on overall heart health.

Effects of calcium and phosphorus enrichment on yield and physiological characteristics of Salicornia persica under different salinity levels

This study aimed at assessing the benefits of phosphate and calcium supplementation to support the growth of Salicornia persica exposed to varying intensities of salinity stress. To achieve this, various concentrations of calcium and phosphorus applied at different levels of salinity under greenhouse conditions with three replications. Under the higher levels of salinity, the decline in shoot biomass is accomplished by the enhancement of leaf water potential. Salinity-challenged plants accumulated both Na+ and soluble sugars, while their content of K+, Ca2+, and Mg2+ ions as well as that of phosphate declined. Supplementation with either calcium or phosphate reduced the uptake of Na, K, and Mg. At 200 mM or 300 mM salinity levels, the plants’ sucrose, fructose, and glucose contents were all correlated with the concentration of calcium. Phosphate supplementation increased the soluble sugar content. Therefore, both calcium and phosphate treatment can be used to ameliorate the biomass production of S. persica in moderate level of salinity.

Calcium interference on americium and plutonium uptake on six extraction chromatographic resins

The retention of americium and plutonium on six commercially available extraction chromatographic resins was investigated in the presence of various concentrations of calcium. Results of batch study experiments showed that there was no significant interference due to calcium for the adsorption of plutonium or americium from both nitric and hydrochloric acid on the majority of the extraction chromatographic resins studied. However, the retention of americium on DGA resin from nitric acid decreased by over two orders of magnitude when calcium was introduced into the system. DGA was found to have a capacity for calcium of 4.53 ± 0.08 mg Ca g−1 DGA resin.

Effects of Calcium Content and Homogenization Method on the Microstructure, Rheology, and Stability of Emulsions Prepared with Soybean Flour Dispersions

The objective is to study the microstructure, rheology, and quiescent stability of oil‐in‐water emulsions prepared with defatted soybean flour dispersions, analyzing the effects of calcium concentration and homogenization method. Dispersions are prepared without or with addition of calcium chloride at different concentrations (30, 60, and 90 mg Ca 100 g−1) and treated by heating (100 °C, 40 min) and high‐pressure homogenization (HPH) at 120 MPa. Emulsions are prepared with homogenized dispersions and sunflower oil by different homogenization methods (high‐speed homogenization, HSH; and HPH at 10 and 20 MPa). The addition of calcium produces a decrease of soluble protein in dispersions, leading to emulsions with higher oil droplet size and aggregation of particles when HSH and HPH are applied, respectively. The highest aggregation degree is observed in the systems with 30 mg Ca 100 g−1, attributed to the formation of a hydrated network of aggregated particles (oil droplets, protein aggregates, and insoluble fibers). Consequently, these emulsions also show the highest viscosity and creaming stability. The findings indicate that calcium can act as a functional ingredient in food emulsions prepared with soybean flour dispersion, because the texture and stability of the system can be controlled by the variation of calcium concentration and homogenization method.Practical Applications: In this study, the impact of calcium addition and homogenization method on the microstructure, rheological behavior, and quiescent stability of o/w emulsions prepared with soybean flour dispersions is assessed. Unlike other works, the strategy used for calcium addition is to promote the interaction of the mineral with proteins and non‐starch polysaccharides present in soybean flour and then reduce the size of aggregates by high‐pressure homogenization. The mentioned strategy can allow the obtaining of vegetable calcium‐rich emulsion‐based products with texture and consistency modulated by the amount of added calcium and the applied homogenization method.Soybean flour dispersions are heated in the presence of different calcium concentrations and then homogenized by high‐pressure homogenization. Emulsions are prepared with homogenized dispersions and sunflower oil by high‐speed or high‐pressure homogenization. The addition of calcium leads to aggregation of particles in emulsions homogenized at high pressure; and good quiescent stability is achieved in emulsions with moderate calcium content.

Human Stem Cell Derived Osteocytes in Bone-on-Chip

ABSTRACTHuman mesenchymal stem cells were reseeded in decellularized human bone subject to a controlled mechanical loading to create a bone-on-chip that was cultured for over 26 months. The cell morphology and their secretome were characterized using immunohistochemistry and in situ immunofluorescence under confocal microscopy. The presence of stem cell derived osteocytes was confirmed at 547 days. Different cell populations were identified. Some cells were connected by long processes and formed a network. Comparison of the MSCs in vitro reorganization and calcium response to in situ mechanical stimulation were compared to MLOY4 cells reseeded on human bone. The bone-on-chip produced an ECM of which the strength was nearly a quarter of native bone after 109 days and that contained calcium minerals at 39 days and type I collagen at 256 days. The cytoplasmic calcium concentration variations seemed to adapt to the expected in vivo mechanical load at the successive stages of cell differentiation in agreement with studies using fluid shear flow stimulation. Some degree of bone-like formation over a long period of time with the formation of a newly formed matrix was observed.

Impact of calcium on healthy lung myofibroblast mobility

Pulmonary fibrosis is an incurable disease belonging to a class of disorders known as Interstitial Lung Diseases, all of which lead to progressive scarring of the lungs. Upon diagnosis, most patients can expect 3-5 years mean survival time. Fibrosis results when “activated” fibroblasts called myofibroblasts are recruited to repair damage, but do not die or migrate away once the repair is complete. Over the last several decades, the calcium ion has been found to have a role in many cellular processes, including migration and death regulation. Our current hypothesis is that the presence of calcium impacts the fate of these cells. Understanding the role calcium plays in healthy myofibroblast migration will provide us with a standard by which we can view diseased myofibroblast migration. We have focused this set of experiments on the response of lung myofibroblasts from a healthy donor to calcium levels to determine a baseline for cell growth and migration using scratch assays. We also measured mitigation of cell death using cytotoxicity assays under varying calcium concentrations. Through scratch assay experiments, we have observed calcium-dependent changes in cell migration. Cytotoxicity data indicate that calcium restriction does not increase mortality of cultured lung myofibroblasts. Immunocytochemistry studies were used to verify that there is no calcium-dependence for cytoplasmic expression of alpha-smooth muscle actin, which indicates the presence of the myofibroblast phenotype. These data align with recent studies that indicate calcium, as a cofactor for nitric oxide synthase, may play a role in the mobility of myofibroblasts in lung tissue.

Molecular insight into the nanoconfined calcite–solution interface

Little is known about the influence of nanoconfinement on calcium carbonate mineralization. Here, colloidal probe atomic force microscopy is used to confine the calcite-solution interface with a silica microsphere and to measure Derjaguin-Landau-Verwey-Overbeek (DLVO) and non-DLVO forces as a function of the calcium concentration, also after charge reversal of both surfaces occurs. Through the statistical analysis of the oscillatory component of a strong hydration force, the subnanometer interfacial structure of the confined atomically flat calcite is resolved in aqueous solution. By applying a mechanical work, both water and hydrated counterions are squeezed out from the nanoconfined solution, leaving the calcite surface more negatively charged than the analogous unconfined surfaces. Layer size and applied work allow a distinction between the hydration states of the counterions in the Stern layer; we propose counterions to be inner- and outer-sphere calcium ions, with a population of inner-sphere calcium ions larger than on unconfined calcite surfaces. It is also shown that the composition of the nanoconfined solution can be tuned by varying calcium concentration. This is a fundamental study of DLVO and hydration forces, and of their connection, on atomically flat calcite. More broadly, our work scrutinizes the greatly unexplored relation between surface science and confined mineralization, with implications for diverse areas of inquiry, such as nanoconfined biomineralization, CO2 sequestration in porous aquifers, and pressure solution and crystallization in confined hydrosystems.

Express determination of coke’s ash content by the gamma-albedo method

Continual monitoring of the ash content is required in fuel processing. The traditional thermogravitational method of determining the ash content is not suitable for use on a large scale, since the analysis is laborious, slow, and destructive. The gamma-albedo method lacks the disadvantages of the standard method and provides results of satisfactory accuracy if the chemical composition of the fuel’s mineral component is relatively constant. In the present work, attention centers on the possibility of express determination of coke’s ash content on the basis of the albedo of low-energy gamma radiation from the Fe-55 radionuclide, with corrections for the variable chemical composition—in particular, fluctuations in the calcium concentration in the ash-forming part of the fuel. To take the perturbing action of calcium into account, the X-ray fluorescence of calcium is measured. The ash content is assessed on the basis of the integral intensity of secondary radiation due to the γ-ray scattering and fluorescence of the calcium. It is clear that artificial attenuation of the secondary radiation is required, in view of the qualitatively different changes in intensity of the fluorescence and scattered radiation as a function of the calcium concentration and also the complex dependence of the integral intensity of the secondary radiation on the ash content. A model is proposed for optimizing the thickness of the attenuating filter so as to ensure equal and opposite changes in the intensity of the fluorescence and scattered radiation with variation in calcium concentration. Recommendations are made for practical application of the proposed method, in terms of the attainment of satisfactory accuracy with fluctuation in the ash content and the composition of the mineral mass. The basic metrological characteristics of the traditional and proposed methods are presented, along with the results of experimental trials.