Calcium Bridge Research Articles

Sustained-release effect of eggshell powder microcapsules on lavender essential oil

Eggshells are rich in Ca2+ and organic compounds, which can be taken as coupling agents for sustained-release materials. Essential oils are widely applied due to their excellent volatility, but poor sustained-release stability has limited their development. The study aimed to develop a novel eggshell powder (EP) sustained-release microcapsule, providing a new approach to protect the active ingredients of Lavender essential oil (LEO), and investigated the reasons for EP to regulate protein-polysaccharide microcapsule structure. Experimental results showed when the addition ratio of EP and Whey protein (WPI) was 1: 3, the dosage of LEO was 25%, the microcapsule displayed smooth and porous spherical structure. XRD and FT-IR indicated that a dense and orderly network structure was formed via the cross-linking reaction between eggshell powder and wall materials, which induced protein and polysaccharide to form special spherical hollow sustained-release shell structure through the calcium bridge (-COO-Ca-COO-), then achieved the sustained-release effect on LEO.

New insights into interaction between oil and solid during hydrothermal treatment of oily sludge

Hydrothermal treatment (HT) can effectively dehydrate and reduce oily sludge (OS) volume, but the resulting hydrothermal oily sludge (HOS) presents greater challenges for washing than the initial oily sludge (IOS). This study examines the effects of HT on OS by analyzing changes in water, oil, and solid. Results indicate that HT considerably decreases the water content in OS while increasing resin and asphaltenes contents. In addition, condensation, side-chain scission, and oxidation reactions occur during the HT process, resulting in coking, agglomeration, and an increase in oxygen-containing groups. This increase, further confirmed by X-ray photoelectron spectroscopy (XPS), enhances the interaction between oil and solids. Calcite, the most prevalent solid-phase component, may form a calcium bridge with the oxygen-containing groups. Moreover, HT reduces the solid particle size, thereby increasing the oil–solid contact area. Interestingly, the process of deasphalting diminishes the interaction between oil and solids, facilitating sludge washing. After washing, the residual oil content in HOS is reduced to less than 0.34%. This study elucidates why HOS is challenging to separate from oil and solids and introduces a novel method that combines dodecylbenzene sulfonic acid (DBSA)-assisted heptane deasphalting with conventional washing techniques. This method shows promise for applications in OS affected by weathering processes.

The Understanding of Vital Pulp Therapy in Permanent Teeth: A New Perspective.

The indications of vital pulp therapy (VPT) are expanding, which cases are suitable for VPT, and how to improve the success rate of VPT is a problem that often bothers us. The main purpose of VPT is to eliminate pulpitis by promoting the formation of reparative dentin or calcium bridge, so that it can continue to perform various physiological functions, and finally achieve the purpose of preserving pulp vitality and long-term preservation of affected teeth. Pulp capping and pulpotomy are the most common methods for VPT. The research field of VPT has attracted the attention of many scholars, who have studied it from many aspects (such as indications, material selection, operation requirements, and long-term prognosis). This article reviews the recent advances in the techniques of VPT in permanent teeth.

Calcium inhibits penetration of Alzheimer's Aβ1 -42 monomers into the membrane.

Calcium ion regulation plays a crucial role in maintaining neuronal functions such as neurotransmitter release and synaptic plasticity. Copper (Cu2+ ) coordination to amyloid-β (Aβ) has accelerated Aβ1-42 aggregation that can trigger calcium dysregulation by enhancing the influx of calcium ions by extensive perturbing integrity of the membranes. Aβ1-42 aggregation, calcium dysregulation, and membrane damage are Alzheimer disease (AD) implications. To gain a detail of calcium ions' role in the full-length Aβ1-42 and Aβ1-42 -Cu2+ monomers contact, the cellular membrane before their aggregation to elucidate the neurotoxicity mechanism, we carried out 2.5μs extensive molecular dynamics simulation (MD) to rigorous explorations of the intriguing feature of the Aβ1-42 and Aβ1-42 -Cu2+ interaction with the dimyristoylphosphatidylcholine (DMPC) bilayer in the presence of calcium ions. The outcome of the results compared to the same simulations without calcium ions. We surprisingly noted robust binding energies between the Aβ1-42 and membrane observed in simulations containing without calcium ions and is two and a half fold lesser in the simulation with calcium ions. Therefore, in the case of the absence of calcium ions, N-terminal residues of Aβ1-42 deeply penetrate from the surface to the center of the bilayer; in contrast to calcium ions presence, the N- and C-terminal residues are involved only in surface contacts through binding phosphate moieties. On the other hand, Aβ1-42 -Cu2+ actively participated in surface bilayer contacts in the absence of calcium ions. These contacts are prevented by forming a calcium bridge between Aβ1-42 -Cu2+ and the DMPC bilayer in the case of calcium ions presence. In a nutshell, Calcium ions do not allow Aβ1-42 penetration into the membranes nor contact of Aβ1-42 -Cu2+ with the membranes. These pieces of information imply that the calcium ions mediate the membrane perturbation via the monomer interactions but do not damage the membrane; they agree with the western blot experimental results of a higher concentration of calcium ions inhibit the membrane pore formation by Aβ peptides.

Preface: Functional biogeography in Japanese cedar

Preface: Functional biogeography in Japanese cedar

Insight into the effect of calcium on bio-clogging behavior via quartz crystal microbalance with dissipation monitoring

Bio-clogging of leachate collection systems has attracted much attention because of its threat to landfill slope stability and landfill landslide events. Calcium in leachate plays a vital role in the formation of bio-clogging. However, the influence of calcium on bio-clogging remains unclear. This study examined the effects of calcium concentration on bio-clogging, including 0, 1.25, 5, 25, and 75 mM CaCl2 groups. A technique involving quartz crystal microbalance with dissipation monitoring (QCM-D) was applied to evaluate the bacteria adhesion behaviors in real time. The results showed that the presence of Ca2+ accelerated the bacterial attachment and increased the viscoelasticity of deposited layers. The deposition mass for 75 mM CaCl2 was 1442 ± 260 ng/cm2, which is 1.5 times that for 1.25 mM CaCl2. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory could explain the bacterial adhesion behaviors in low calcium concentrations (<25 mM). In comparison, the effect of calcium bridge was shown in high calcium concentrations (>25 mM). The development of biofilms was a dynamic process, and the Ca2+ concentration was positively related to the amount of biofilm generated. In low CaCl2 concentration (less than 5 mM) groups, the degree of bio-clogging increased from the exponential growth phase to the decline phase; in contrast, in high CaCl2 concentration (above 25 mM) groups, the degree of bio-clogging increased and later declined. Therefore, the calcium concentration should be controlled at a low level in leachate to mitigate bio-clogging in LCSs.

COVID-19: the CaMKII-like system of S protein drives membrane fusion and induces syncytial multinucleated giant cells.

The SARS-CoV-2 S protein on the membrane of infected cells can promote receptor-dependent syncytia formation, relating to extensive tissue damage and lymphocyte elimination. In this case, it is challenging to obtain neutralizing antibodies and prevent them through antibodies effectively. Considering that, in the current study, structural domain search methods are adopted to analyze the SARS-CoV-2 S protein to find the fusion mechanism. The results show that after the EF-hand domain of S protein bound to calcium ions, S2 protein had CaMKII protein activities. Besides, the CaMKII_AD domain of S2 changed S2 conformation, facilitating the formation of HR1-HR2 six-helix bundles. Apart from that, the Ca2+-ATPase of S2 pumped calcium ions from the virus cytoplasm to help membrane fusion, while motor structures of S drove the CaATP_NAI and CaMKII_AD domains to extend to the outside and combined the viral membrane and the cell membrane, thus forming a calcium bridge. Furthermore, the phospholipid-flipping-ATPase released water, triggering lipid mixing and fusion and generating fusion pores. Then, motor structures promoted fusion pore extension, followed by the cytoplasmic contents of the virus being discharged into the cell cytoplasm. After that, the membrane of the virus slid onto the cell membrane along the flowing membrane on the gap of the three CaATP_NAI. At last, the HR1-HR2 hexamer would fall into the cytoplasm or stay on the cell membrane. Therefore, the CaMKII_like system of S protein facilitated membrane fusion for further inducing syncytial multinucleated giant cells.

Determinants of paravalvular leakage following transcatheter aortic valve replacement in patients with bicuspid and tricuspid aortic stenosis.

Paravalvular leakage (PVL) after transcatheter aortic valve replacement (TAVR) is a common complication in patients with bicuspid aortic valve (BAV). However, predictors and mechanisms of PVL are not well understood in this subset. The aim of this study was to analyse determinants and mechanisms of PVL in BAV and tricuspid aortic valve (TAV). Of the 2394 consecutive patients undergoing transfemoral TAVR using new-generation valves at our centre, we identified 242 cases with BAV. To adjust for baseline differences, we performed 3 : 1 propensity score matching (TAVPS n = 726). We analysed the aortic root anatomy and calcification as well as the number, circumferential distribution, and predilection sites of PVL using pre-procedural multidetector computed tomography and post-TAVR echocardiography. In the matched cohort, the incidence of PVL ≥mild (BAV 51.9% vs. TAVPS 51.7%; P = 0.955) and PVL ≥moderate (BAV 5.0% vs. TAVPS 3.7%; P = 0.393), the circumferential distribution, and independent predictors were similar between BAV and TAVPS. Both the presence of peri-annular calcium chunks or LVOT calcification were highly associated with PVL in BAV and TAVPS patients, whereas in BAV patients neither the presence of a calcium bridge nor the volume of its calcification was related to PVL. Notably, the spatial localization of these lesions did not necessarily match the circumferential leak position. The incidence, circumferential distribution, predilection sites, and predictors of PVL were similar in matched population of BAV and TAVPS patients undergoing transfemoral TAVR using new-generation devices. These novel findings suggest a common underlying mechanism of PVL in both entities.

Transcatheter aortic valve implantation for tricuspid aortic valve with a calcium bridge between the cusps: a case report.

BackgroundIndications for transcatheter aortic valve (AV) implantation (TAVI) have been extended to patients with challenging anatomical features such as a bicuspid AV. However, no case reports of TAVI for tricuspid AV with a ‘calcium bridge’ have been published.Case summaryWe report the case of an 87-year-old woman with severe symptomatic aortic stenosis (AS). Pre-procedural multidetector computed tomography (MDCT) showed a calcium bridge between the non-coronary and left cusps. Although these cusps appeared to be fused together in the centre by the calcium bridge, the commissure area between the fused cusps appeared to normally open. We cracked apart the calcium bridge from the commissure area using balloon aortic valvuloplasty, which was guided by transoesophageal echocardiography. Subsequently, we successfully implanted a balloon-expandable transcatheter heart valve (THV).DiscussionTo our knowledge, this is the first report of TAVI for a tricuspid AV with a ‘calcium bridge’ between the non-coronary and left cusps. In our patient, the unique structure of cusp fusing in the centre seemed to be caused by an acquired atherosclerotic process, as documented using a contemporary technique, i.e. MDCT. Cracking the calcium bridge with a balloon aortic valvuloplasty ensured that the THV adequately expanded. Severe AS caused by a calcium bridge may be treated with detailed evaluation of the AV morphology together with a procedural strategy planning.

Combined membrane filtration and alcohol-precipitation of alkaline soluble polysaccharides from sugar beet pulp: Comparision of compositional, macromolecular, and emulsifying properties

Alkaline soluble polysaccharide 1 (ASP1) was a polysaccharide extracted from residues remaining from the extraction of sugar beet pulp. This study aimed to separate ASP1 into five different fractions, named UP, UR, F50, F65 and F75, by using ultrafiltration membrane and stepwise alcohol-precipitation. The results showed that the fractions differed from each other regarding their chemical and macromolecular features. The Mw of these sub-fractions decreased in the order of F65 (340 kg mol−1), UR (325 kg mol−1), F75 (295 kg mol−1), F50 (278 kg mol−1) and UP (78 kg mol−1). The emulsifying properties of these fractions in oil-in-water systems containing 10% w/w MCT were compared, taking ASP1 as the reference. At concentrations of 1% of each polysaccharide, F75 showed the best emulsifying activity with the d4,3 value of 0.35 μm, while the droplet size for UP was 10 times greater than the others.After storage at 60 °C for seven days, emulsion stability decreased in the order of F65, UR, ASP1, F75, F50 and UP, based on the d4,3 value increment of 0.27 μm, 0.95 μm, 1.48 μm, 3.33 μm, 3.99 μm and 21.5 μm, respectively. Due to the occurrence of calcium bridge flocculation, most polysaccharides in this work could not stabilize oil-in-water systems into homogeneous emulsions, except F65 and F75, in which d4,3 values were increased from 1.22 and 0.72 μm to 13.7 and 3.6 μm, respectively, after storage, demonstrating great resistance to calcium for F75.In conclusion, membrane filtration combined with alcohol-precipitation is feasible to separate the mother polysaccharide into sub-fractions with different emulsifying properties, among which selected fractions exhibiting superior emulsifying properties could be used as potential emulsifiers in low-calcium systems.

Gelling mechanism and interactions of polysaccharides from Mesona blumes: Role of urea and calcium ions

In this study, the relaxation modulus was used to elucidate the gelling mechanism of polysaccharides from Mesona blumes. The pH of Mesona blumes polysaccharides (MBP) was adjusted could significantly change the relaxation modulus of MBP. The results showed that the hydrogen bonds and electrostatic interaction existed in during the formation of MBP gel. The addition of salt ions (sodium ions and calcium ions), EDTA and urea have different effects on the relaxation modulus of MBP. Result showed that the hydrogen bond was the main force maintaining the MBP gel network structure, followed was calcium ions. And electrostatic interaction was not the decisive role of gel formation. The small molecules with active hydrogen-bond donors and/or acceptors were added into MBP, which proved −COOH was involved in the hydrogen bonds formation of MBP gel. In addition, the entanglement network number (ENN) results quantitatively assessed contribution of interaction: hydrogen bonds interaction > calcium ions (calcium bridge) >electrostatic interaction.

Aggregation behavior of TiO2 nanoparticles in municipal effluent: Influence of ionic strengthen and organic compounds

The influence of ionic strengthen and dissolved organic matter (DOM) on the aggregation of TiO2 nanoparticles (NPs) in municipal effluent was investigated. The results demonstrated that DOM promoted the mobility of NPs in aquatic system by synergism between static repulsion and steric effect, while electrolytes were opposite by charge-neutralization. The physical-chemical characteristics of DOM played the major role on the mobility of NPs. Bovine serum albumin (BSA) showed the strongest enhancement on the mobility of TiO2 NPs. High adsorption of BSA introduced vast negative charges on the TiO2 NPs' surface, leading to static repulsion and neutralizing positive charges of electrolytes in surrounding as well. By contrast, another protein α-amylase retarded the aggregation rate of TiO2 NPs through steric repulsion of the long-chain construction. Humic substances (Fulvic acid and alginate) also reflected the combination of static repulsion and steric effect. However, in the high electrolytes concentration (especially Ca2+), the long-chain aliphatic compounds were prone to form calcium bridge which increased the hydrodynamic diameter of TiO2 aggregates consequently. Sodium dodecylbenzene sulfonate (SDBS) showed low adsorption capacity, while the unabsorbed SDBS retarded the aggregates caused by the changes of pH and electrolytes. These data indicated that decreasing of DOC concentration in aqueous system was important to reduce the mobility and potential risk of NPs in aqueous system.

Wettability Alteration by Salinity and Calcium Bridge in a Crude Oil/Brine/Rock System

Wettability alteration has been considered to be a key factor behind low salinity water effect. Though the wettability alteration is widely accepted to be determined by oil components, mineral surfaces and ions in aqueous phase, how the brine chemistry (ionic type and strength) impacts the wettability is still unknown. In this study, the auhtors conducted spontaneous imbibition, contact angle, and zeta potential measurements to investigate: (a) how the ions of the thin film of water between oil and mineral interact with oil and rock to alter the wettability of crude oil/brine/rock system and (b) the mechanism of wettability alteration behind low salinity water effect.

Biochemical and physiological study of the firmness of table grape berries

Firmness is an essential quality parameter of table grapes (Vitis vinifera) for consumers, with grape bunches that contains soft berries less preferred, resulting in a reduction in the market price. The softening of grape berries has been commonly associated with cell walls, especially the disassembly of pectic polysaccharides. However, the process of berry softening is not completely understood. To investigate the softening process of grape berries, we compared the Thompson Seedless variety, which suffers significant economic losses due to fruit softening, and NN107, a new variety with a significantly higher level of berry firmness. The composition of the cell wall during the berry development of these two grape varieties was compared. NN107 berries had a greater amount of calcium and uronic acids in the cell wall material than Thompson Seedless grapes, suggesting a special role for calcium bridge formation in NN107. Additionally, polyacrylamide carbohydrate electrophoresis (PACE) analysis suggested differences between these varieties in pectin structure. Thompson Seedless grapes showed increased pectolyase hydrolysable site dynamics in the cell wall material and higher polygalacturonase activity than NN107. Immunohistochemistry focusing on the pectin structure confirmed the roles of both calcium bridge formation and cell wall integrity as they relate to a firmer grape berry phenotype.

High‐temperature conditioning induces chilling tolerance in mandarin fruit: a cell wall approach

High-temperature conditioning (3 days at 37 °C and 95% relative humidity), which protects 'Fortune' mandarins from chilling injury (CI), manifested as pitting in the outer part of the peel (flavedo), was applied prior to cold storage (2 °C) in order to investigate the involvement of cell wall composition in the chilling tolerance of mandarins. Both low-temperature storage and high-temperature conditioning barely modified the alcohol-insoluble substance (AIS) content or the degree of pectin esterification in the flavedo. Water-soluble pectins (WSP) were higher in heat-conditioned than in non-conditioned fruits at the onset of CI. In addition, the heat-conditioning treatment was able to increase chelator-soluble pectins (CSP) after short cold storage periods. Covalently bound polyuronides in alkali-soluble pectins (ASP) increased only in fruits with high incidence of CI. Cellulose and hemicellulose increased at 2 °C in both conditioned and non-conditioned fruits, indicating that these polysaccharides may be altered by low temperature but are not related to chilling-induced damage. High-temperature conditioning may reduce chilling-induced flavedo pitting in 'Fortune' mandarin fruit by maintaining normal levels of WSP and increasing putative sites for calcium bridge formation within the cell wall, but not by inducing changes in other matrix cell wall components.

Calcium Bridge Triggers Capsid Disassembly in the Cell Entry Process of Simian Virus 40

The calcium bridge between the pentamers of polyoma viruses maintains capsid metastability. It has been shown that viral infection is profoundly inhibited by the substitution of lysine for glutamate in one calcium-binding residue of the SV40 capsid protein, VP1. However, it is unclear how the calcium bridge affects SV40 infectivity. In this in vitro study, we analyzed the influence of host cell components on SV40 capsid stability. We used an SV40 mutant capsid (E330K) in which lysine had been substituted for glutamate 330 in protein VP1. The mutant capsid retained the ability to interact with the SV40 cellular receptor GM1, and the internalized mutant capsid accumulated in caveolin-1-mediated endocytic vesicles and was then translocated to the endoplasmic reticulum (ER) region. However, when placed in ER-rich microsome, the mutant capsid retained its spherical structure in contrast to the wild type, which disassembled. Structural analysis of the mutant capsid with cryo-electron microscopy and image reconstruction revealed altered pentamer coordination, possibly as a result of electrostatic interaction, although its overall structure resembled that of the wild type. These results indicate that the calcium ion serves as a trigger at the pentamer interface, which switches on capsid disassembly, and that the failure of the E330K mutant capsid to disassemble is attributable to an inadequate triggering system. Our data also indicate that calcium depletion-induced SV40 capsid disassembly may occur in the ER region and that this is essential for successful SV40 infection.

FLOCCULATION-SOME OBSERVATIONS ON THE SURFACE CHARGES OF YEAST CELLS

Surface charges on flocculent and non-flocculent yeast cells have been measured by micro-electrophoresis. Yeasts were grown both in calcium deficient and in complete medium and particular attention was paid to changes as cells passed from a logarithimic to a stationary phase of growth. Many of the ionogenic groups contributing to surface charge are situated well within the cell wall; charges on cells from the calcium-deficient medium were higher than on cells from the complete medium. A pH-dependent rearrangement of an underlying surface protein layer is postulated for the flocculent yeast Saccharomyces cerevisiae Strain NCYC 1109. No evidence of a similar rearrangement was found with other flocculent strains examined. The results are discussed in relation to ‘calcium bridge’ formation.

Fourier transform phosphorus magnetic resonance study of ATP -- calcium -- G-actin complex

31P-Fourier transform NMR spectroscopy (40.5 MHz) has been employed to investigate the mode of binding of adenosine 5′-triphosphate (ATP) to rabbit muscle G-actin in the presence of calcium in the pH range 6.5 to 10.5. Line width measurements reveal that the nucleotide binds tightest around pH=8.5. Spin lattice (T 1) and spin-spin (T 2) relaxation times of each of the three phosphorus atoms of bound ATP demonstrate the prime importance of P β and P γ in ATP binding to G-actin through a calcium bridge.