Search Results (2,560)

The mechanism of dolomite has been a major hotspot in geological research. However, most of the current studies mainly focus on single microorganisms and fail to fully consider the influence of marine microbial diversity on the precipitation of carbonate rock minerals. In this paper, two marine microorganisms (Bacillus sp. and Virgibacilus oceani), which can induce dolomite precipitation, were selected to induce dolomite precipitation in a culture solution that simulated the Mg²⁺/Ca²⁺ of modern oceans. Four systems were set up in this experiment, including the Bacillus sp. system, the Virgibacilus oceani system, the co-precipitation system (Bacillus sp. and Virgibacilus oceani), and the control system. The synergistic promotion of the dolomite was analyzed by comparing the changes in solution pH, ion consumption, morphology, mineralogical phase, and thermal stability in each experimental group. The experimental results show that the increase in pH value and the consumption of Mg²⁺ and Ca²⁺ in the coexistence of Bacillus sp. and Virgibacilus oceani are greater than those in the single microorganism system. The minerals induced by Bacillus sp. and Virgibacilus oceani were mostly small calcium carbonate particles and a small amount of proto-dolomite. However, the faster precipitation rates, larger particle diameters, higher proportion of proto-dolomite, and higher thermal stability of the calcium carbonate and proto-dolomite induced by the two microorganisms suggest that biomineralization facilitates the formation of stable dolomite and accelerates the precipitation of Mg²⁺ and Ca²⁺ for bioremediation purposes. Full article

The cytosolic pH (pH_i) of mammalian cells is tightly maintained at values ~7.2. Cytoplasmic acidosis (pH_i < 6.8) occurs when the intracellular proton concentration ([H⁺]_i) exceeds the buffering capacity of the cytosol and transport processes to extrude protons are exhausted. During intracellular acidosis, the contractility of cardiac and skeletal muscle cells is strongly reduced, often at sufficient Ca²⁺ levels. A contraction of striated muscle is achieved when the intracellular calcium (Ca²⁺) concentration rises above resting levels. The amplitude and kinetics of Ca²⁺ signals are controlled by Ca²⁺ handling proteins and force is generated if Ca²⁺ ions interact with contractile filaments of the sarcomere. Some aspects of this phenomenon, such as the biochemical origin of excessive protons in working muscle cells and molecular interactions of protons with Ca²⁺ handling proteins or contractile filaments, are not yet fully understood. This review summarizes our current understanding of how striated muscle cells handle Ca²⁺ and H⁺ and how a rise in [H⁺]_i may interfere with Ca²⁺ signaling in the working skeletal muscle (fatigue) or during ischemic events in cardiac muscle. Finally, we briefly address experimental strategies to measure Ca²⁺ signaling at different pH values with fluorescent probes and highlight their limitations. Full article

The TMEM16 (Anoctamin) family comprises a group of transmembrane proteins involved in diverse physiological processes, including ion transport and phospholipid scrambling. TMEM16F (Anoctamin 6), a phospholipid scramblase and nonselective ion channel, plays a central role in membrane remodeling, blood coagulation, immune responses, and cell death pathways through its ability to externalize phosphatidylserine in response to elevated intracellular calcium levels. Consequently, modulating TMEM16F activity has emerged as a promising strategy for the development of new therapeutic applications. Despite the functional importance of TMEM16F, TMEM16F modulators have received little study. In a previous study, we generated TMEM16F-specific affibodies by biopanning a phage display library for affibodies that bind to brain-specific TMEM16F (hTMEM16F) variant 1. In this study, we selected six other affibodies from among the 38 previously sequenced affibody candidates and characterized them. After purification, we confirmed that two of these affibodies bound to human TMEM16F with high affinity. To provide functional insights into how these affibodies modulate TMEM16F activity, we tested whether they could exert functional effects at the cellular level. Finally, we show that TMEM16F affibody attenuated the neuronal cell death induced by glutamate and microglial phagocytosis, suggesting that these affibodies might have potential therapeutic and diagnostic applications. Full article

A widely used approach for synthesizing hydroxyapatite (HA) particles is the wet chemical precipitation method, favoured for its cost-effectiveness and straightforward process. Incorporating organic macromolecules with polar functional groups, such as COOH and OH, during synthesis can impact the properties of the resulting HA particles. These functional groups enhance the affinity for positively charged Ca²⁺ ions, promoting HA crystal nucleation in the solution. In this study, solutions at different concentrations of chitosan and sodium alginate are used as nucleation medium for the HA particles in order to decrease their particle size. The calcium and phosphate precursor solutions were adjusted to a pH of 12 and added to the polymer solution with a concentration varying from 5 to 10% w/v, reported to the stoichiometric mass of HA according to the synthesis reaction. After synthesis, the resulting powder was calcinated at 1000 °C. The effects that the polymers have on the properties of HA particles were monitored using SEM, FT-IR, EDAX, DLS, and TGA before and after the thermal treatment to see how the system evolves till crystallization of HA occurs. The largest decrease in average particle diameter—67.7%—was observed in the HA + Alg 10% sample, although a reduction in particle size was evident in all samples. Full article

Octacalcium phosphate (OCP) is a calcium phosphate compound with a layered structure in which apatite layers, which have a structure similar to hydroxyapatite, and hydrated layers are stacked alternately. OCP can incorporate various carboxylate ions into its interlayers. OCPs with incorporated carboxylate ions, also known as OCP carboxylates (OCPCs), are organically modified at the molecular level. OCPCs are an attractive research target in a wide range of fields, from basic inorganic chemistry to applied materials chemistry. Therefore, it is expected that a comprehensive overview of recent research on OCPCs will be useful in progressing this field. This review focuses on recent advances in OCPCs, namely their synthesis, the identification of new types of carboxylate ions that can be incorporated into OCP interlayers, the steric structure estimation of the interlayer carboxylate ions, and applications of OCPCs as functional materials. OCPC-based functional materials include fluorescent materials, artificial bones, and adsorbents. Furthermore, based on existing studies, challenges in OCPC research and future research directions are described. Full article

Nelumbo nucifera (lotus) has long been used in traditional medicine across Asia, and its bioactive alkaloids have recently garnered attention for their neuroprotective properties. This review summarizes the current research on the mechanisms by which lotus-derived alkaloids, particularly neferine, nuciferine, liensinine, and isoliensinine, protect neural tissues. These compounds exhibit a wide range of pharmacological activities, including antioxidant and anti-inflammatory effects, regulation of calcium signaling and ion channels, promotion of neurogenesis, and modulation of key neurotransmitter systems, such as dopaminergic, cholinergic, and GABAergic pathways. Notably, they attenuate tau hyperphosphorylation, reduce oxidative stress-induced neuronal apoptosis, and enhance neurotrophic signaling via BDNF-related pathways. While antioxidant and anti-inflammatory actions are the most extensively studied, emerging evidence also highlights their roles in autophagy modulation and mitochondrial protection. Together, these findings suggest that lotus alkaloids are promising candidates for the prevention and treatment of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases. Further investigation is warranted to explore the synergistic mechanisms and potential clinical applications of these compounds. Full article

Excessive stress disrupts cardiac homeostasis via complex and multifactorial mechanisms, resulting in cardiac dysfunction, cardiovascular disease, or even sudden cardiac death, yet the underlying molecular mechanisms remain poorly understood. Accordingly, we aimed to elucidate how stress induces calcium dysregulation and contributes to cardiac dysfunction and injury through the nuclear receptor subfamily 3 group c member 1 (NR3C1)/Glomulin (GLMN)/FK506-binding protein 12.6 (FKBP12.6) signaling pathway. Using mouse models of acute and chronic restraint stress, we observed that stress-exposed mice exhibited reduced left ventricular ejection fraction, ventricular wall thickening, elevated serum and myocardial cTnI levels, along with pathological features of myocardial ischemia and hypoxia, through morphological, functional, and hormonal assessments. Using transmission electron microscopy and Western blotting, we found that stress disrupted mitochondrial quality control in cardiomyocytes, evidenced by progressive mitochondrial swelling, cristae rupture, decreased expression of fusion proteins (MFN1/OPA1) and biogenesis regulator PGC-1α, along with aberrant accumulation of fission protein (FIS1) and autophagy marker LC3. At the cellular level, ChIP-qPCR and siRNA knockdown confirmed that stress activates the glucocorticoid receptor NR3C1 to repress its downstream target GLMN, thereby preventing FKBP12.6 ubiquitination and degradation, resulting in calcium leakage and overload, which ultimately impairs mitochondrial quality control and damages cardiomyocytes. In conclusion, our findings reveal that stress induces myocardial damage through NR3C1/GLMN-mediated FKBP12.6 ubiquitination, disrupting calcium homeostasis and mitochondrial quality control, and lay a theoretical foundation for dissecting the intricate molecular network of stress-induced cardiomyopathy. Full article

Cirrhotic cardiomyopathy (CCM) is a cardiac dysfunction in patients with cirrhosis, occurring in the absence of structural heart disease. It increases perioperative risk, especially in liver transplantation, and may contribute to hepatorenal syndrome. Despite its clinical significance, CCM remains poorly understood and lacks effective treatments. This review aims to summarize recent findings on the pathogenesis of CCM and highlight potential therapeutic targets. A focused literature review was conducted using PubMed, Scopus, and Clarivate databases, selecting studies from the last five years. Included studies investigated molecular, cellular, and receptor-mediated mechanisms involved in CCM. Results: CCM results from neurohumoral, inflammatory, and electrophysiological disturbances. Key mechanisms involve dysfunction of β-adrenergic and muscarinic receptors, altered ion channels (potassium, L-type calcium), impaired sodium–calcium exchange, and suppression of the P2X7 receptor (P2X7R). Dysregulation of the CD73 (5’-nucleotidase, ecto-5’-nucleotidase)–A2 adenosine axis, along with effects from endocannabinoids, nitric oxide (NO) inhibition by tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6), carbon monoxide (CO), and elevated galectin-3 (Gal-3), further contribute to myocardial dysfunction. Conclusions: CCM is a multifactorial condition linked to systemic and myocardial effects of cirrhosis. A deeper understanding of its mechanisms is essential for developing targeted therapies. Further research is needed to improve patient outcomes. Full article

The objective of this study was to assess the content of selected elements—fluorine, calcium and inorganic phosphorus—in infusions prepared from selected commercial leaf teas available on the Polish market. A comprehensive analysis was conducted based on tea type and geographical origin. In addition, the Target Hazard Quotient (THQ) was calculated to estimate the non-carcinogenic health risk associated with fluoride intake from tea consumption. Methods: A total of 98 leaf tea samples were analyzed, including 55 black, 27 green, 9 oolong, and 7 white teas. Standardized brewing protocols were applied. Measured parameters included pH, calcium and inorganic phosphorus content, buffer capacity, and titratable acidity. Fluoride concentrations were determined using an ion-selective electrode. Statistical analysis was performed using non-parametric methods (Kruskal–Wallis ANOVA with DSCF post hoc test), and heatmaps were generated to illustrate the distribution of THQ across different models. Results: Black teas exhibited significantly lower pH values and higher titratable acidity, buffer capacity, and inorganic phosphorus levels compared to other tea types, indicating distinct physicochemical properties. Although all THQ values for fluoride remained well below the safety threshold (THQ < 1), the highest values were observed in elderly individuals with low body weight, particularly women consuming green tea, suggesting increased vulnerability in this subgroup. Conclusions: Among the analyzed samples, black teas demonstrated the most distinct chemical profile, characterized by the lowest pH and the highest acidity, buffer capacity, and fluoride and phosphorus content—especially in teas originating from Africa and Central Asia. While fluoride exposure from leaf tea infusions does not appear to pose a direct health risk, older adults, particularly low-weight women, may be more susceptible to potential non-carcinogenic effects and should moderate their intake of high-fluoride teas. Full article

This study aims to develop environmentally friendly soil-stabilization materials by investigating the synergistic enhancement mechanism of industrial by-product lignin fibers (LFs) and sodium sulfate (Na₂SO₄) on the mechanical and micro-structural properties of cement-stabilized soil. A systematic evaluation was conducted through unconfined compressive strength (UCS), splitting tensile strength, and capillary water absorption tests, supplemented by microscopic analyses including XRD and SEM. The results indicate that the optimal synergistic effect occurs at 1.0% LF and 0.10% Na₂SO₄, which increases UCS and splitting tensile strength by 9.23% and 18.37%, respectively, compared to cement-stabilized soil. Meanwhile, early strength development is accelerated. Microscopically, LF physically bridges soil particles, forming aggregates, reducing porosity, and enhancing cohesion. Chemically, Na₂SO₄ acts as an activator, accelerating cement hydration and stimulating pozzolanic reactions to form calcium aluminosilicate hydrate and gypsum, which fill pores and densify the matrix. The synergistic mechanism lies in Na₂SO₄ enhancing the interaction between the LFs and clay minerals through ion exchange, facilitating the formation of a stable spatial network structure that inhibits particle sliding and crack propagation. This technology offers substantial sustainability benefits by utilizing paper-making waste LF and low-cost Na₂SO₄ to improve soil strength, toughness, and impermeability. Full article

Background: A trilayered collagen/collagen–magnesium–hydroxyapatite (Col/Col-Mg-HA) scaffold is used in clinical practice to treat osteochondral lesions, but the regeneration of the subchondral bone is still not satisfactory. Objective: The aim of this study was to test, in vitro, the osteoinductivity induced by the addition of bone morphogenetic protein-2 (BMP-2) or amorphous calcium phosphate granules with strontium ions (Sr-ACP), in order to improve the clinical regeneration of subchondral bone, still incomplete. Methodology: Normal human osteoblasts (NHOsts) were seeded on the scaffolds and grown for 14 days in the presence of human osteoclasts and conditioned medium of human endothelial cells. NHOst adhesion and morphology were observed with transmission electron microscopy, and metabolic activity was tested by Alamar blue assay. The expression of osteoblast- and osteoclast-typical markers was evaluated by RT-PCR on scaffolds modified by enrichment with BPM-2 or Sr-ACP, as well as on unmodified material used as a control. Results: NHOsts adhered well to all types of scaffolds, maintained their typical morphology, and secreted abundant extracellular matrix. On the modified materials, COL1A1, SPARC, SPP1, and BGLAP were more expressed than on the unmodified ones, showing the highest expression in the presence of BMP-2. On Sr-ACP-enriched scaffolds, NHOsts had a lower proliferation rate and a lower expression of RUNX2, SP7, and ALPL compared to the other materials. The modified scaffolds, particularly the one containing Sr-ACP, increased the expression of the osteoclasts’ typical markers and decreased the OPG/RANKL ratio. Both types of scaffold modification were able to increase the osteoinductivity with respect to the original scaffold used in clinical practice. BMP-2 modification seemed to be more slightly oriented to sustain NHOst activity, and Sr-ACP seemed to be more slightly oriented to sustain the osteoclast activity. These could provide a concerted action toward better regeneration of the entire osteochondral unit. Full article

3,4-dihydroxybenzenesulfonyl-functionalized polyethyleneimine (PS), a novel polymeric chelator, was synthesized by conjugating 3,4-dihydroxybenzenesulfonyl (CAM) groups with branched polyethyleneimine (BPEI, MW = 600 Da) via N-acylation. PS demonstrated a high uranium adsorption capacity of 78.08% at a concentration of 4 mg/mL, accompanied by significant selectivity over competing ions such as Ca²⁺, Zn²⁺, and Cu²⁺. Notably, in competitive adsorption experiments, PS exhibited a uranium adsorption rate of 59.49%, which was 3.95 times higher than that of calcium (15.06%) in the Ca²⁺ system. Cytotoxicity assays revealed enhanced biocompatibility (IC₅₀ = 86.98 μg/mL), surpassing CaNa₃-DTPA 3.7-fold. In a uranium exposure model (200 μg/mL), PS significantly improved cell survival rates and reduced intracellular uranium levels by 77.37% (immediate administration) and 64.18% (delayed administration). These findings establish PS as a potent and safe polymeric chelator for uranium decorporation, offering a promising strategy for mitigating the hazards of radioactive materials. Full article

Calcium ions (Ca²⁺) play a vital role in many biological processes. Transmembrane and coiled-coil domain 1 (TMCO1) has been characterized as an endoplasmic reticulum (ER) transmembrane protein in recent years. It keeps the cytoplasm and ER’s Ca²⁺ homeostasis stable by acting as a novel calcium channel. Studies from different laboratories have revealed that the mutation or deficiency of TMCO1 is closely correlated with several diseases, including cerebro-facio-thoracic dysplasia (CFTD), glaucoma, premature ovarian failure (POF), osteoporosis, and cancer. Here, we review the characteristics of TMCO1 and its involvement in related diseases, which may provide useful information for developing therapeutic strategies for these diseases, as well as promote further research on this protein. Full article

The state of the art in the thermodynamics of calix[4]resorcinarene derivatives and its metal ion complexes is briefly discussed in the introduction. This is followed by the synthesis and characterization of a recyclable calix[4]resorcinarene amide derivative (L). The 1H NMR analyses in CD3CN and CD3OD showed solvent-dependent conformational changes with a notable downfield chemical shift in the aromatic proton (H-2) in moving from deuterated methanol to acetonitrile, indicating an interaction of the solvent within the ligand cavity as suggested by molecular dynamic simulations. 1H NMR complexation in acetonitrile revealed that L forms relatively strong 1:1 complexes with cations, with selectivity for Ca(II) and, to lesser extent, with Pb(II) over other metal cations. The composition of the complexes is corroborated by conductance measurements. The thermodynamics of these systems indicate that the complexation process is predominantly enthalpy controlled in acetonitrile, while it is entropy controlled in methanol. A remarkable outcome of fundamental studies is found in its application as new material for the removal of Ca(II) from water. The capacity of L to remove Ca(II) from water is 24 mmol/g which exceeds by far the capacity of cation exchange resins. Full article

Tungsten disulfide (WS₂), a two-dimensional layered material with favorable electronic properties, has been explored as a promising negative electrode material for calcium-ion batteries (CIBs). Despite its use in monovalent systems, its performance in divalent Ca²⁺ intercalation remains poorly understood. Herein, a combined theoretical and experimental framework is used to elucidate the electronic mechanisms underlying Ca²⁺ intercalation. Theoretical insights were obtained through density functional theory calculations, incorporating periodic simulations using the Vienna Ab initio Simulation Package, and localized orbital-level analysis using the discrete variational Xα method. These approaches reveal that Ca²⁺ insertion induces significant interlayer expansion, lowers diffusion barriers, and narrows the bandgap compared to Li⁺. Orbital analysis revealed strengthened W–S bonding and diminished antibonding interactions, which may contribute to the improved structural resilience. Electrochemical tests validated these predictions; the CaWS₂ electrode delivered an initial discharge capacity of 208 mAh·g⁻¹ at 0.1C, with 61% retention after 50 cycles at 1C. The voltage profile exhibits a distinct plateau near 0.7 V, consistent with a two-phase-like intercalation mechanism, contrasting with the gradual slope observed for Li⁺. These findings suggest that Ca²⁺ intercalation facilitates both rapid ion transport and enhanced structural robustness. This study offers mechanistic insights into multivalent-ion storage and supports the design of high-performance CIB electrodes. Full article