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Purpose We aimed to investigate the effect of metal ions from oral prostheses (OPs) released into the saliva of patients with oral lichenoid lesions (OLLs). Materials and methods Subjects (n=183) were divided into four groups according to the presence or absence of OLL and OP. Concentrations of the metal ions titanium, chromium (Cr), cobalt (Co), nickel (Ni), palladium (Pd), silver (Ag), platinum (Pt), gold (Au), and zirconium (Zr) were measured using a laser-ablation microprobe inductively coupled to a plasma mass spectrometer. Saliva levels of interleukin (IL)-6, IL-1β, IL-8, and tumor necrosis factor-α were detected using an enzyme-linked immunosorbent assay. The reticulation/keratosis, erythema, and ulceration (REU) scoring system was used to assess the severity of OLL. Results Mean concentrations of IL-6 and IL-8 were statistically higher in OLL patients with OPs. The concentration of Ni was high in OLL groups. The concentrations of Cr, Ni, and Au ions in the saliva were positively correlated with IL-8. REU scores were positively correlated with salivary concentrations of IL-6 and IL-8, as well as with concentrations of Cr, Ni, and Au. Conclusion Increased concentrations of metal ions, especially Ni, in saliva were positively correlated with IL-8 and showed positive correlations with the severity of OLL.

In this study, contrary to untreated poplar fiber, processing of alkali-treated poplar fiber was optimized for the enzymatic saccharification. Considering reducing sugar content as the evaluation index, pH, temperature, time, amount of enzyme, and rotational speed of shaker were standardized to optimize the sugar production by enzymatic hydrolysis. Using response surface methodology, the optimum technological condition of enzymatic hydrolysis was found to be utilizing 43 mg cellulase at 46 °C for 50 h. At this, the sugar conversion amount of NaOH or H2O2-NaOH pretreated poplar was 164.62 mg/g and 218.82 mg/g respectively. It was a corresponding increase of 446.73% or 626.75% than that of poplar fiber without a pretreatment. At a low concentration, metal ions and surfactants promoted the conversion of reducing sugar. Especially, 0.01 g/L Mn2+ and 0.50 g/L hexadecyl trimethyl ammonium bromide (CTAB) produced the best effect and increased the conversion rate of reducing sugar by 23.62% and 21.44% respectively. Also, the effect of the combination of metal ions and surfactants was better than that of a single accelerator. By improving the enzymatic process, these findings could enhance the utilization of poplar fiber for the production of reducing sugar., GRAPHICAL ABSTRACT

The current study portrays a dispersive solid-phase extraction as a silica nanoparticle-covered Graphene Oxide(GO-SiO2) synthesised with some modification as in the literature and developed removal/preconcentration method for selective extraction of some heavy metal in water samples. Flame atomic absorption spectrophotometry (FAAS) was used to measure in optimum conditions for the proposed method. Field emission scanning electron microscope (FESEM) and X-beam diffraction (XRD) were utilised for the characterisation of solid phase. The developed method presents high surface areas for sorption capacity and a low amount of solid phase. The removal percentage was performed at approximately 100% with pH 4 to 10 for all metal ions. According to validation results under the optimised method, the limits of detection (LODs) and quantification (LOQs) were found in the range of 5.8–23.0 µg L−1 and 16.0 − 38.1 µg L−1, respectively. The developed method was applied by using certified reference material (BCR 715) for trueness, which observed high relative recovery with lower than 11.8% relative error except for Pb and Cd. The comparison between the experimental results and the certified reference material indicated that the accuracy of the method is higher than 90%. The proposed method was effectively practised for five water samples with standard addition. © 2020 Informa UK Limited, trading as Taylor & Francis Group.

Pyrene-based materials have gained considerable attention as stimuli-responsive chemical sensors. We designed a polysulfurated arene system based on a tetra(phenylthio)pyrene core decorated with four carboxylic acid units. Three different regioisomers, ortho, meta and para were studied in organic and aqueous solution. These systems are soluble in water at pH≥8 due to the deprotonation of carboxylic acids. The addition of metal ions cannot only quench the fluorescence of the central pyrene core, but also control the formation of three-dimensional nanoscopic objects in a dual mode function. Several divalent metal ions were tested and compared. Addition of ethylenediaminetetraacetic acid (EDTA) disassembles the non-emissive supramolecular system and restores the initial fluorescence of the pyrene core.

Deinococcus radiodurans can survive under extreme conditions, including high doses of DNA damaging agents and ionizing radiation, desiccation, and oxidative stress. Both the efficient cellular DNA repair machinery and antioxidation systems contribute to the extreme resistance of this bacterium, making it an ideal organism for studying the cellular mechanisms of environmental adaptation. The number of stress-related proteins identified in this bacterium has mushroomed in the past two decades. The newly identified proteins reveal both commonalities and diversity of structure, mechanism, and function, which impact a wide range of cellular functions. Here, we review the unique and general structural features of these proteins and discuss how these studies improve our understanding of the environmental stress adaptation mechanisms of D. radiodurans.

Significance CRISPR-Cas12a has emerged as attractive molecular scissors alternative to Cas9 owing to its unique features including fewer off-target effects, an alternative protospacer-adjacent motif sequence, pre-CRISPR RNA processing activity, and indiscriminate single-stranded DNase activity. However, despite these advantages, Cas12a has not been well utilized as recently reported base and prime editors because it does not have complete nickase variants, unlike Cas9. In this study, we provide a thorough understanding of the mechanisms that govern the generation of complete double-stranded DNA breaks by the single catalytic site of Cas12a using single-molecule fluorescence assays to improve our ability to develop a rational design for more potently engineered Cas12a including the nickase form. This would extend the range of genome editing applications of Cas12a., CRISPR-Cas12a, an RNA-guided DNA targeting endonuclease, has been widely used for genome editing and nucleic acid detection. As part of the essential processes for both of these applications, the two strands of double-stranded DNA are sequentially cleaved by a single catalytic site of Cas12a, but the mechanistic details that govern the generation of complete breaks in double-stranded DNA remain to be elucidated. Here, using single-molecule fluorescence resonance energy transfer assay, we identified two conformational intermediates that form consecutively following the initial cleavage of the nontarget strand. Specifically, these two intermediates are the result of further unwinding of the target DNA in the protospacer-adjacent motif (PAM)–distal region and the subsequent binding of the target strand to the catalytic site. Notably, the PAM-distal DNA unwound conformation was stabilized by Mg2+ ions, thereby significantly promoting the binding and cleavage of the target strand. These findings enabled us to propose a Mg2+-dependent kinetic model for the mechanism whereby Cas12a achieves cleavage of the target DNA, highlighting the presence of conformational rearrangements for the complete cleavage of the double-stranded DNA target.

A silver ion high-speed counter-current chromatography ([Ag+]-HSCCC) was developed to separate and purify five sesquiterpenoids from germacrene A fermentation broth. The solvent system was consisted of n-hexane-methanol-silver nitrate (3 mol/L) solution (10:9.5:0.5, v/v). By employing this chromatographic protocol, five sesquiterpenoids named β-elemene (1, 54.1 mg), germacrene A (2, 28.5 mg), γ-selinene (3, 4.6 mg), β-selinene (4, 3.4 mg), and α-selinene (5, 1.3 mg) were obtained successfully from 500 mg extracted crude sample with purities of 97.1%, 95.2%, 98.2%, 96.3% and 98.5%, respectively, combined with preparative HPLC. The results reveal that the addition of metal ion in biphasic solvent system significantly improved the HSCCC separation factor of sesquiterpenoids. Meanwhile, our study also provided an alternate approach to separate the compounds with less polarity, also geometrical isomers and various natural product classes.

Mesoporous bioactive glass nanoparticles (MBGNPs) are attracting significant attention as suitable materials for multifunctional biomedical applications. In this study, cerium was incorporated into MBGNPs using two different approaches. In the first approach, cerium was added to the glass system directly during the synthesis, while in the second approach, cerium was added to the as-synthesized MBGNPs via the template ion-exchange method. The influence of the method of synthesis on the physicochemical properties of nanoparticles was examined by SEM, TEM, XRD, FTIR, and N2 adsorption-desorption analyses. The MBGNPs exhibited spheroidal morphology and disordered mesoporous structure. XRD analysis confirmed the amorphous nature of the nanoparticles. The chemical composition was determined by the acid digestion method using ICP-OES. The influence of the synthesis method on the specific surface area, mesoporosity, and solubility of synthesized nanoparticles in Tris/HCl (pH 7.4) and acetate (pH 4.5) buffer has also been studied. The obtained Ce containing MBGNPs were non-cytotoxic toward ​preosteoblast MC3T3-E1 cells in contact with nanoparticles in a concentration of up to 100 ​μg/mL. The anti-inflammatory effect of Ce containing MBGNPs was tested with lipopolysaccharides (LPS)-induced proinflammatory RAW 264.7 macrophage cells. Ce containing MBGNPs decreased the release of nitric oxide, indicating the anti-inflammatory response of macrophage cells. Ce containing MBGNPs also showed antibacterial activity against S. aureus and E. coli. The mentioned features of the obtained MBGNPs make them useful in a variety of biomedical applications, considering their biocompatibility, anti-inflammatory response, and enhanced antibacterial effect., Graphical abstract Image 1

Two-component systems (TCSs) are essential for bacteria to sense, respond, and adapt to changing environments, such as elevation of Cu(I)/Ag(I) ions in the periplasm. In Escherichia coli, the CusS–CusR TCS up-regulates the cusCFBA genes under increased periplasmic Cu(I)/Ag(I) concentrations to help maintain metal ion homeostasis. The CusS histidine kinase is a homodimeric integral membrane protein that binds to periplasmic Cu(I)/Ag(I) and transduces a signal to its cytoplasmic kinase domain. However, the mechanism of how metal binding in the periplasm activates autophosphorylation in the cytoplasm is unknown. Here, we report that only one of the two metal ion-binding sites in CusS enhances dimerization of the sensor domain. Utilizing nanodisc technology to study full-length CusS, we show that metal-induced dimerization in the sensor domain triggers kinase activity in the cytoplasmic domain. We also investigated autophosphorylation in the cytoplasmic domain of CusS and phosphotransfer between CusS and CusR. In vitro analyses show that CusS autophosphorylates its conserved H271 residue at the N1 position of the histidine imidazole. The phosphoryl group is removed by the response regulator CusR in a reaction that requires a conserved aspartate at position 51. Functional analyses in vivo of CusS and CusR variants with mutations in the autophosphorylation or phosphoacceptor residues suggest that the phosphotransfer event is essential for metal resistance in E. coli. Biochemical analysis shows that the CusS dimer autophosphorylates using a cis mechanism. Our results support a signal transduction model in which rotation and bending movements in the cytoplasmic domain maintain the mode of autophosphorylation.

Sugarcane bagasse cellulose mixed ester succinate phthalate (SBSPh) was synthesized by a novel one-pot reaction method. The effects of temperature, time and mole fraction of succinic anhydride (χSA) on the responses weight gain (wg), number of carboxylic acid groups (nT,COOH), and adsorption capacity (q) of Co2+ and Ni2+ were evaluated by a 23 experimental design. The chemical structure of the material was elucidated by Fourier transform infrared, 13C Multiple Cross-Polarization solid-state NMR spectroscopy and 1H NMR relaxometry. The best SBSPh synthesis condition (100 °C, 11 h, χSA of 0.2) yielded a wg of 59.1%, nT,COOH of 3.41 mmol g−1, and values of qCo2+ and qNi2+ of 0.348 and 0.346 mmol g−1, respectively. The Sips model fitted better the equilibrium data, and the maximum adsorption capacities (pH 5.75 and 25 °C) estimated by this model were 0.62 and 0.53 mmol g−1 for Co2+ and Ni2+, respectively. The ΔadsH° values estimated by isothermal titration calorimetry were 8.43 and 7.79 kJ mol−1 for Co2+ and Ni2+, respectively. Desorption and re-adsorption efficiencies were evaluated by a 22 experimental design, which showed that SBSPh adsorbent can be recovered and reused without significant loss of adsorption capacity.

Inhalational exposure to dust from engineered stone (ES), also known as artificial or composite stone, is associated with a specific disease profile, namely accelerated silicosis, and scleroderma. The pathogenic mechanisms are poorly understood, particularly the role of resin and metal ions. Metal ions are present in pigments and constituent minerals and may be considered potential contributors to toxicity. The aim of this preliminary study was to understand the solubility of ES-containing metals in artificial lysosomal fluid (ALF) simulating the acidic intracellular environment of the lung macrophage lysosome. Differences with respect to ES types and temporal release were explored. Ten ES products of variable colour and company origin were comminuted and assessed for four different metals, solubilized into ALF solutions at 1,2,4 and 8 weeks at 37 °C. There was significant variability in metal release, particularly with regard to iron and manganese, which could be correlated with the reflected brightness of the stone. A majority of the available Mn, Fe, Al and Ti was solubilized. Time trends for metal release varied with ES type but also with metal ion. The data suggest a high metal ion bioavailability once engulfed by lung macrophages. There is a need to investigate a wider range of ES dust and relate metal content to markers of ES toxicity.

Made available in DSpace on 2022-05-01T03:42:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Fundação de Amparo à Pesquisa do Estado de Mato Grosso Solid-state M-Val compounds were synthesized, where M stands for bivalent metals (Mn, Fe, Co, Ni, Cu, and Zn), and Val stands for valsartanate ion (C24H27N5O32−). The thermal and spectroscopic study of the compounds was performed using TG-DSC, FTIR, DRX, as well as the evolved gas analysis (EGA) by TG/DSC-FTIR. The thermoanalytical results showed information about the stoichiometry of the compounds (1:1), the degree of hydration, and thermal behavior. The EGA results allowed the identification of the aliphatic hydrocarbons, carbon monoxide, carbon dioxide, and ammonia for both Valsartan and metal compounds. The theoretical and experimental spectroscopic data suggested the possible modes of coordination of the ligand with the metal ions by coordinating bonding with the oxygen of the carboxylate and the tetrazole group's nitrogen. The association of Cu (II) and Co (II) metal ions with Val improves the antimicrobial activity against E. coli. Lames-Instituto de Química Universidade Federal de Goiás Departamento de Química Faculdade de Ciências Universidade Estadual Paulista Departamento de Fisico-Química/IQ Universidade Estadual de Campinas Departamento de Botânica e Ecologia/IB Universidade Federal de Mato Grosso GENMAT/LACANM Departamento de Química/ICET Universidade Federal de Mato Grosso Departamento de Química Faculdade de Ciências Universidade Estadual Paulista

Olive stone is an important biomaterial waste product generated in large amount. As a lignocellulose material, olive stone could be a sustainable resource for biosorbents. In this work, olive stone powder delignification using sodium chlorite (NaClO2) was performed to enhance metal ion adsorption capacity. The influence of the treatment on olive stone powder physical-chemical properties was studied, including specific surface area, surface chemistry, morphology, etc. The white, delignified olive stone powder was applied for metal ions (Fe3+, Cu2+, and Zn2+) adsorption. Olive stone delignification not only increases the accessibility of the olive stone powder but also broadens the applications to materials design with optical functions by the generation of a white powder.

The available drug therapy for post-ischemic neurodegeneration of the brain is symptomatic. This review provides an evaluation of possible dietary therapy for post-ischemic neurodegeneration with myricetin. The purpose of this review was to provide a comprehensive overview of what scientists have done regarding the benefits of myricetin in post-ischemic neurodegeneration. The data in this article contribute to a better understanding of the potential benefits of myricetin in the treatment of post-ischemic brain neurodegeneration, and inform physicians, scientists and patients, as well as their caregivers, about treatment options. Due to the pleiotropic properties of myricetin, including anti-amyloid, anti-phosphorylation of tau protein, anti-inflammatory, anti-oxidant and autophagous, as well as increasing acetylcholine, myricetin is a promising candidate for treatment after ischemia brain neurodegeneration with full-blown dementia. In this way, it may gain interest as a potential substance for the prophylaxis of the development of post-ischemic brain neurodegeneration. It is a safe substance, commercially available, inexpensive and registered as a pro-health product in the US and Europe. Taken together, the evidence available in the review on the therapeutic potential of myricetin provides helpful insight into the potential clinical utility of myricetin in treating neurodegenerative disorders with full-blown dementia. Therefore, myricetin may be a promising complementary agent in the future against the development of post-ischemic brain neurodegeneration. Indeed, there is a scientific rationale for the use of myricetin in the prevention and treatment of brain neurodegeneration caused by ischemia.

Compositions of stainless steel, nickel-titanium, cobalt-chromium and &beta, titanium orthodontic alloys were simulated with mixtures of Fe, Ni, Cr, Co, Ti and Mo metal ions as potential oxidative stress-triggering agents. Wild-type yeast Saccharomyces cerevisiae and two mutants &Delta, Sod1 and &Delta, Ctt1 were used as model organisms to assess the cytotoxicity and oxidative stress occurrence. Metal mixtures at concentrations of 1, 10, 100 and 1000 &micro, M were prepared out of metal chlorides and used to treat yeast cells for 24 h. Every simulated orthodontic alloy at 1000 &micro, M was cytotoxic, and, in the case of cobalt-chromium alloy, even 100 &micro, M was cytotoxic. Reactive oxygen species and oxidative damage were detected for stainless steel and both cobalt-chromium alloys at 1000 &micro, M in wild-type yeast and 100 &micro, M in the &Delta, Ctt1 mutants. Simulated nickel-titanium and &beta, titanium alloy did not induce oxidative stress in any of the tested strains.

Byssus is a thread-like seafood waste that has a natural high efficiency in anchoring many metal ions thanks to its richness of diverse functional groups. It also has structural stability in extreme chemical, physical and mechanical conditions. The combination of these properties, absent in other waste materials, has novelty suggested its use as matrix for water remediation. Thus, pristine byssus, upon de-metalation, was studied to remove metal ions from ideal solutions at pH 4 and 7, as model chemical systems of industrial and environmental polluted waters, respectively. The byssus matrix’s uptake of metal ions was determined by ICP-OES and its surface microstructure investigated by SEM. The results showed that the byssus matrix excellently uptakes metal ions slightly reorganizing its surface micro-structure. As example of its efficiency: 50 mg of byssus absorbed 21.7 mg·g−1 of Cd2+ from a 10 mM solution at pH 7. The adsorption isotherm models of Freundlich and Langmuir were mainly used to describe the system at pH 7 and pH 4, respectively. In conclusion, we showed that the byssus, a waste material that is an environmental issue, has the potential to purify polluted industrial and environmental waters from metal ions.

While fibrillar deposits of hyperphosphorylated protein tau are a key hallmark of several neurodegenerative diseases such as Alzheimer's disease, small oligomers have been speculated to be the key toxic aggregate species. Trivalent metal ions were shown to promote tau oligomer formation in vitro. However, little is known about potential intercellular spreading mechanisms or toxic modes of action of such oligomers. We investigated interactions of tau monomers and Fe3+/Al3+-induced oligomers with small unilamellar vesicles derived from 1-palmitoyl-2-oleoyl-phosphatidylcholine (neutral, liquid-crystalline phase) and dipalmitoyl-phosphatidylcholine (neutral, gel-phase). We further evaluated the influence of glycogen synthase kinase 3β (GSK-3β)-mediated tau phosphorylation applying the single-particle fluorescence spectroscopy techniques fluorescence correlation spectroscopy, fluorescence intensity distribution analysis, and scanning for intensely fluorescent targets. In these experiments, no binding to neutral lipid surfaces was observed for tau monomers. In contrast, metal-ion-induced tau oligomers showed a gain of function in binding to neutral lipid surfaces. Of note, tau phosphorylation by GSK-3β increased both oligomer formation and membrane affinity of the resulting oligomers. In conclusion, our data imply a pathological gain of function of metal-ion-induced oligomers of hyperphosphorylated tau, enabling membrane binding irrespective of surface charge even at nanomolar protein concentrations.

Aquaporin-4 (AQP4) is the main water channel protein expressed in the central nervous system (CNS). AQP4 is densely expressed in astrocyte end-feet, and is an important factor in CNS water and potassium homeostasis. Changes in AQP4 activity and expression have been implicated in several CNS disorders, including (but not limited to) epilepsy, edema, stroke, and glioblastoma. For this reason, many studies have been done to understand the various ways in which AQP4 is regulated endogenously, and could be regulated pharmaceutically. In particular, four regulatory methods have been thoroughly studied; regulation of gene expression via microRNAs, regulation of AQP4 channel gating/trafficking via phosphorylation, regulation of water permeability using heavy metal ions, and regulation of water permeability using small molecule inhibitors. A major challenge when studying AQP4 regulation is inter-method variability. A compound or phosphorylation which shows an inhibitory effect in vitro may show no effect in a different in vitro method, or even show an increase in AQP4 expression in vivo. Although a large amount of variability exists between in vitro methods, some microRNAs, heavy metal ions, and two small molecule inhibitors, acetazolamide and TGN-020, have shown promise in the field of AQP4 regulation.

Peptides are considered very important due to the diversity expressed through their amino acid sequence, structure variation, large spectrum, and their essential role in biological systems. Antimicrobial peptides (AMPs) emerged as a potent tool in therapy owing to their antimicrobial properties but also their ability to trespass the membranes, specificity, and low toxicity. They comprise a variety of peptides from which specific amino acid-rich peptides are of interest to the current review due to their features in metal interaction and cell penetration. Histidine-rich peptides such as Histatins belong to the metal binding salivary residing peptides with efficient antibacterial, antifungal, and wound-healing activities. Furthermore, their ability to activate in acidic environment attracted the attention to their potential in therapy. The current review covers the current knowledge about AMPs and critically assess the potential of associating with metal ions both structurally and functionally. This review provides interesting hints for the advantages provided by AMPs and metal ions in biomedicine, making use of their direct properties in brain diseases therapy or in the creation of new bio-functionalized nanoparticles for cancer diagnosis and treatment. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

The widespread uptake and use of emissive metal ion complexes for investigating cellular structure, composition and function, is evidence of the effectiveness and vast potential for this type of imaging probe. Metal ion complexes provide significant advantages over their organic fluorophore counterparts, including long emission lifetime, resistance to photobleaching and the capacity to readily modify their peripheral chemistry to target specific organelles, signalling pathways and individual molecules. This review will discuss recent progress in the development and use of metal ion complexes, specifically for studying metabolic diseases at the cellular level. Advanced metal ion complexes for organelle imaging and the detection of biorelevant species, to elaborate complexes for understanding cellular mechanisms and recent therapeutic applications will be reviewed. To align with the special issue, Coordination Chemistry Reviews: Coordination Chemistry in Australia, the work of Australian researchers actively engaged in this field is featured prominently, along with key developments from the global research community. Refereed/Peer-reviewed

The CAZY family GH124 endoglucanase from Ruminiclostridium thermocellum contains an unusual metal-ion site featuring a covalently modified ‘2-oxohistidine’ residue. Atomic resolution (∼1 Å) three-dimensional analyses, in conjunction with ITC and mass spectrometry, show that this metal site can accommodate a diverse array of transition metals, all of which confer a stabilizing effect on the enzyme., The recent discovery of ‘lytic’ polysaccharide monooxygenases, copper-dependent enzymes for biomass degradation, has provided new impetus for the analysis of unusual metal-ion sites in carbohydrate-active enzymes. In this context, the CAZY family GH124 endoglucanase from Ruminiclostridium thermocellum contains an unusual metal-ion site, which was originally modelled as a Ca2+ site but features aspartic acid, asparagine and two histidine imidazoles as coordinating residues, which are more consistent with a transition-metal binding environment. It was sought to analyse whether the GH124 metal-ion site might accommodate other metals. It is demonstrated through thermal unfolding experiments that this metal-ion site can accommodate a range of transition metals (Fe2+, Cu2+, Mn2+ and Ni2+), whilst the three-dimensional structure and mass spectrometry show that one of the histidines is partially covalently modified and is present as a 2-oxohistidine residue; a feature that is rarely observed but that is believed to be involved in an ‘off-switch’ to transition-metal binding. Atomic resolution (

Summary The HCN1–4 channel family is responsible for the hyperpolarization-activated cation current If/Ih that controls automaticity in cardiac and neuronal pacemaker cells. We present cryoelectron microscopy (cryo-EM) structures of HCN4 in the presence or absence of bound cAMP, displaying the pore domain in closed and open conformations. Analysis of cAMP-bound and -unbound structures sheds light on how ligand-induced transitions in the channel cytosolic portion mediate the effect of cAMP on channel gating and highlights the regulatory role of a Mg2+ coordination site formed between the C-linker and the S4-S5 linker. Comparison of open/closed pore states shows that the cytosolic gate opens through concerted movements of the S5 and S6 transmembrane helices. Furthermore, in combination with molecular dynamics analyses, the open pore structures provide insights into the mechanisms of K+/Na+ permeation. Our results contribute mechanistic understanding on HCN channel gating, cyclic nucleotide-dependent modulation, and ion permeation., Graphical abstract, Highlights • HCN4 structure is shown in ligand-free and ligand-bound state • Pore domain is shown in closed and in open configuration • Permeability and selectivity mechanisms of HCN channels are uncovered • A metal ion coordination site functionally couples cytoplasmic and transmembrane domains, HCN4 channels underlie the pacemaker current that controls heart rate. Saponaro et al. report the structure of HCN4 with the pore in closed and in open configuration and provide information on ion permeability and selectivity. In HCN4, a metal ion coordination site functionally connects the C-linker to the S4-S5 linker.

This study describes the use of succinylated twice-mercerized sugarcane bagasse containing adsorbed Cu 2+ or Ni 2+ ions from spiked aqueous solutions (2MSBA-Cu and 2MSBA-Ni) as heterogeneous catalysts for the catalytic oxidation of n -hexane and n -heptane in gas phase. To the best of our knowledge, this is the first study in which a spent adsorbent material based on lignocellulose biomass is used in the catalytic oxidation of volatile organic compounds. The adsorbent and spent adsorbent materials were characterized by FTIR, TGA and XRD. The amount of Cu 2+ and Ni 2+ adsorbed on 2MSBA was 0.49 and 2.49 mmol g −1 , respectively. The catalysts were active for total oxidation of n -hexane and n -heptane, even at low temperatures. 2MSBA-Cu exhibited higher catalytic activity than 2MSBA-Ni and surprisingly their performances were comparable or superior to those of some catalysts reported in the literature, including noble metal-based catalysts.

The oxidation reaction of ferrocene derivatives is important because of its biological applications. The reactivity is affected by metal ions. However, it is not clear how to interact the metal ions with the ferrocenes. In this paper, the oxidation reactivity of (o-acetylphenyl)ferrocene was investigated in the view of solvent effect and the addition effect of salicylic acid. Furthermore, the measurement of the relaxation time was carried out. As a result, Al 3+ would strongly interact with (o-acetylphenyl)ferrocene so that prevent the mobility of the acetyl group.

A hydrophilic and anti-fouling coating layer was constructed on a polyvinylidene fluoride (PVDF) microfiltration membrane by a novel surface modification method. The pristine membrane was firstly coated by (3-chloropropyl) trimethoxysilane/polyethyleneimine and tannic acid. Then, the metal ion was induced on the coating layer to coordinate with tannic acid and polyethyleneimine, forming a more stable and hydrophilic coating on the surface. The membrane&rsquo, s surface morphology and chemical element analysis showed that the Tannic acid/ polyethyleneimine (TA/PEI) coating layer was denser and had more stability after the addition of metal ions, and this may be due to the coordination bond formed between the TA/PEI coating and metal ions. The results of the water contact angle and pure water flux measurements showed that the hydrophilicity and wettability of the modified membranes were improved obviously after introducing the metal ion layers. The anti-fouling performance and stability of the modified membrane were also characterized by the underwater oil contact angle (OCA), the separation efficiency, and the contact angle variation value for before and after the rinsing experiment. The modified membrane showed obvious stability and antifouling. Moreover, the retention rate of some composite membranes could reach 99.6%.

The main objective of this work was to evaluate the potential of Montmorillonite nanoclay (Mt), readily and inexpensively available, for the simultaneous adsorption (and removal) of two classes of pollutants: metal ions and dyes. The attention was focused on two &ldquo, model&rdquo, pollutants: Ce(III) and crystal violet (CV). The choice is due to the fact that they are widespread in wastewaters of various origins. These characteristics, together with their effect on human health, make them ideal for studies on water remediation. Moreover, when separated from wastewater, they can be recycled individually in industrial production with no or simple treatment. Clay/pollutant hybrids were prepared under different pH conditions and characterized through the construction of the adsorption isotherms and powder X-ray diffraction. The adsorption behavior of the two contaminants was revealed to be significantly different: the Langmuir model reproduces the adsorption isotherm of Ce(III) better, thus indicating that the clay offers a unique adsorption site to the metal ions, while the Freundlich model proved to be the most reliable for the uptake of CV which implies heterogeneity of adsorption sites. Moreover, metal ions do not adsorb at all under acidic conditions, whereas the dye is able to adsorb under all the investigated conditions. The possibility to modulate the adsorption features by simply changing the pH conditions was successfully employed to develop an efficient protocol for the removal and separation of the different components from aqueous solutions mimicking wastewaters.

The present article reviews the clinical use of thiol-based metal chelators in intoxications and overexposure with mercury (Hg), cadmium (Cd), and lead (Pb). Currently, very few commercially available pharmaceuticals can successfully reduce or prevent the toxicity of these metals. The metal chelator meso-2,3-dimercaptosuccinic acid (DMSA) is considerably less toxic than the classical agent British anti-Lewisite (BAL, 2,3-dimercaptopropanol) and is the recommended agent in poisonings with Pb and organic Hg. Its toxicity is also lower than that of DMPS (dimercaptopropane sulfonate), although DMPS is the recommended agent in acute poisonings with Hg salts. It is suggested that intracellular Cd deposits and cerebral deposits of inorganic Hg, to some extent, can be mobilized by a combination of antidotes, but clinical experience with such combinations are lacking. Alpha-lipoic acid (α-LA) has been suggested for toxic metal detoxification but is not considered a drug of choice in clinical practice. The molecular mechanisms and chemical equilibria of complex formation of the chelators with the metal ions Hg2+, Cd2+, and Pb2+ are reviewed since insight into these reactions can provide a basis for further development of therapeutics. Keywords: BAL; DMPS; DMSA; metal chelator; metal ion This research was funded by Regione Autonoma della Sardegna, grant number “RASSR79857”, by Ministero dell’Istruzione, dell’Università e della Ricerca, grant number (PON RI 2014-2020) and by Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja (Project III 46009.

Solute carrier (SLC) transporters meditate many essential physiological functions, including nutrient uptake, ion influx/efflux, and waste disposal. In its protective role against tumors and infections, the mammalian immune system coordinates complex signals to support the proliferation, differentiation, and effector function of individual cell subsets. Recent research in this area has yielded surprising findings on the roles of solute carrier transporters, which were discovered to regulate lymphocyte signaling and control their differentiation, function, and fate by modulating diverse metabolic pathways and balanced levels of different metabolites. In this review, we present current information mainly on glucose transporters, amino-acid transporters, and metal ion transporters, which are critically important for mediating immune cell homeostasis in many different pathological conditions., Graphical abstract Solute carrier (SLC) transporters meditate many essential physiological functions. In this review, we present current information mainly on glucose transporters, amino-acid transporters, and metal ion transporters, which are critically important for mediating immune cell homeostasis in many different pathological conditions.Image 1

Four specifically designed IDE mutants have been used to unveil the molecular basis of peptidase versus E1-like activity of the enzyme. We have found that physiological concentrations of copper(ii) ions inhibit the proteolytic activity of the enzyme towards small and large substrates but have no effect on the E1-like activity of the enzyme.

Fructose 1,6-bisphosphate aldolase (FBA) is important for both glycolysis and gluconeogenesis in life. Class II (zinc dependent) FBA is an attractive target for the development of antibiotics against protozoa, bacteria, and fungi, and is also widely used to produce various high-value stereoisomers in the chemical and pharmaceutical industry. In this study, the crystal structures of class II Escherichia coli FBA (EcFBA) were determined from four different crystals, with resolutions between 1.8 A and 2.0 A. Native EcFBA structures showed two separate sites of Zn1 (interior position) and Zn2 (active site surface position) for Zn2＋ ion. Citrate and TRIS bound EcFBA structures showed Zn2＋ position exclusively at Zn2. Crystallographic snapshots of EcFBA structures with and without ligand binding proposed the rationale of metal shift at the active site, which might be a hidden mechanism to keep the trace metal cofactor Zn2＋ within EcFBA without losing it. [BMB Reports 2016; 49(12): 681-686].

ObjectivesThis study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion.MethodsThe 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris.ResultsThe CoC/ABG Modular patients had a mean age of 64.6 years (49.4 to 76.5) and ASR/SROM patients had a mean age of 58.2 years (33.3 to 85.6). The mean time in situ for CoC/ABG was 4.9 years (2 to 6.4) and ASR/SROM was 6.1 years (2.5 to 8.1). The blood serum metal ion concentrations reduced following revision surgery with the exception of Cr levels within CoC/ABG. The grading of tissue sections showed that the macrophage response and metal debris were significantly higher for the ASR/SROM patients (p < 0.001). The brown/red particles were significantly higher for ASR/SROM (p < 0.001). The taper debris contained traces of titanium oxide, chromium oxide and aluminium nitride.ConclusionThis study characterised and qualitatively graded the severity of the corrosion particles released into the hip joint from tapers that had corrosion damage. Cite this article: S. Munir, R. A. Oliver, B. Zicat, W. L. Walter, W. K. Walter, W. R. Walsh. The histological and elemental characterisation of corrosion particles from taper junctions. Bone Joint Res 2016;5:370–378. DOI: 10.1302/2046-3758.59.2000507.

The active phase responsible for low-temperature CO oxidation in nanoparticulate CuO/CeO2 catalysts was identified as surface-substituted CuyCe1-yO2-x. Contrary to previous studies, our measurements on a library of well-defined CuO/CeO2 catalysts have proven that the CuO phase is a spectator species, whereas the surface-substituted CuyCe1-yO2-x phase is active for CO oxidation. Using in situ X-ray absorption spectroscopy, we found that the copper ions in CuyCe1-yO2-x remain at high oxidation states (Cu3+ and Cu2+) under oxygen-rich catalytic conditions without any evidence for Cu+. Artificial neural network potential Monte Carlo simulations suggest that Cu3+ and Cu2+ preferentially segregate to the {100} surface of the CuyCe1-yO2-x nanoparticle, which is supported by aberration-corrected electron microscopy measurements. These results pave the way for understanding, at the atomic level, the mechanisms and descriptors pertinent for CO oxidation on these materials and hence the rational design of next-generation catalysts.

Due to the complexity of heterogeneous catalysts, identification of active sites and the ways for their experimental design are not inherently straightforward but important for tailored catalyst preparation. The present study reveals the active sites for efficient C–H bond activation in C1–C4 alkanes over ZrO2 free of any metals or metal oxides usually catalysing this reaction. Quantum chemical calculations suggest that two Zr cations located at an oxygen vacancy are responsible for the homolytic C–H bond dissociation. This pathway differs from that reported for other metal oxides used for alkane activation, where metal cation and neighbouring lattice oxygen form the active site. The concentration of anion vacancies in ZrO2 can be controlled through adjusting the crystallite size. Accordingly designed ZrO2 shows industrially relevant activity and durability in non-oxidative propane dehydrogenation and performs superior to state-of-the-art catalysts possessing Pt, CrOx, GaOx or VOx species. Identifying active sites and designing rationally heterogeneous catalysts are not inherently straightforward due to their complexity. Here, the authors reveal the nature of active sites for efficient C–H bond activation in C1-C4 alkanes over bare ZrO2 and provide fundamentals for controlling their concentration.

The interactions of nucleic acid bases with non-coordinated and coordinated water molecules were studied by analyzing data in the Protein Data Bank (PDB) and by quantum chemical calculations. The analysis of the data in the crystal structures from the PDB indicates that hydrogen bonds involving oxygen or nitrogen atoms of nucleic acid bases and water molecules are shorter when water is bonded to a metal ion. These results are in agreement with the quantum chemical calculations on geometries and interaction energies of hydrogen bonds; the calculations on model systems show that hydrogen bonds of nucleic acid bases with water bonded to a metal ion are stronger than hydrogen bonds with non-coordinated water. These calculated values are similar to the strength of hydrogen bonds between nucleic acid bases. The results presented in this paper may be relevant to understand the role of water molecules and metal ions in the process of replication and stabilization of nucleic acids and also to understand the possible toxicity of metal ion interactions with nucleic acids. Supplementary information: [https://cer.ihtm.bg.ac.rs/handle/123456789/4863]

Yüksek seçicilik ve duyarlılığa sahip kemosensörlerin tasarımı ve geliştirilmesi son yıllarda aktif olarak araştırılmaktadır. İnsan sağlığı ve çevre için oldukça büyük etkilere sahip olan anyon ve katyonları algılayabilen kemosensörler kimyagerler, biyologlar, klinik biyokimyacılar ve çevre bilimciler gibi pek çok bilim insanının ilgisini çekmiştir. Bazı metal iyonları sinir impulslarının iletimi, kas kasılması ve hücre aktivitesinin düzenlenmesi gibi biyolojik proseslerde rol oynamaktadır. Hatta çeşitli metal iyonları bazı metalloenzimlere aittir. Bazı metal iyonlarının ise organizma için toksik olduğu bilinmektedir. Bu nedenle, metal iyonlarının belirlenmesinde sensör olarak kullanılabilecek yeni bileşiklerin sentezi oldukça önem arz etmektedir. Bu çalışmada metal iyonların tanınmasında kullanılabilecek antrasen temelli iki yeni Schiff Bazı 1,2-bis(3-(Antrasen-9-ilmetilen)aminopropoksi)benzen (5) ve N-(9-antrasenilmetilen)-4-naftil-2-tiyazolamin (7) sentezlendi. Bileşiklerin yapıları 1H, 13C, APT, COSY NMR ve FT-IR spektrumları aracılığıyla aydınlatıldı. Sentezlenen bileşiklerin Li+, Na+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Zn2+, Cd2+, Hg2+, Al3+ ve Pb2+ metal iyonlarını tayin etme yeteneği incelendi. Bileşik 5'in koloritmetik olarak Fe3+ iyonuna karşı ve bileşik 7'nin ise Hg2+ iyonuna karşı kolorimetrik tepki verdiği belirlenmiştir., The design and development of chemical sensors with high specificity and sensitivity is under active investigation in recent years. Chemosensors which has huge implications for human health and the environment and can detect anions and cations, have attracted the interest of many scientists such as chemists, biologists, environmental scientists and clinical biochemists. Some metal ions are involved in biological processes such as transmission of nerve impulses, muscle contraction and modulation of cell activity. Even various metal ions belong to certain metalloenzymes. Some metal ions are known to be toxic for the organism. Therefore, the synthesis of new compounds which can be used as sensor for the determination of metal ions is highly important. In the present study, two new anthracene based Schiff Base derivatives, 1,2-bis(3-(anthracene-9-ylmethylene)aminopropoxy)benzene (5) and N-(9-anthracenylmethylene)-4-napthyl-2-thiazolamine (7) were synthesized for the determination of metal ions. Structures of compounds were confirmed by 1H, 13C, APT, COSY NMR ve FT-IR spectra. The sensing ability of synthesized compunds to determine metal ions Li+, Na+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Zn2+, Cd2+, Hg2+, Al3+ ve Pb2+ was investigated. It was determined that compound 5 displays colorimetric response towards Fe3+ ion and compound 7 displays colorimetric response towards Hg2+ ion., Bu tez çalışması Selçuk Üniversitesi Bilimsel Araştırmalar Koordinatörlüğü tarafından 16401147 nolu proje ile desteklenmiştir.

In this paper, we present the fabrication and characterization of new chitosan-based membranes while using a new biotechnology for immobilizing alkaline phosphatase (ALP). This technology involved metal ions incorporation to develop new biopolymeric supports. The chemical structure and morphological characteristics of proposed membranes were evaluated by infrared spectroscopy (FT-IR) and the scanning electron microscopy technique (SEM). The inductively coupled plasma mass spectrometry (ICP-MS) evidenced the metal ion release in time. Moreover, the effect of Mg2+ on the enzymatic activity and the antibacterial investigations while using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, hemolysis, and biocompatibility behavior were studied. Immobilizing ALP into the chitosan membranes composition followed by the incorporation of Mg2+ led to polymeric supports with enhanced cellular viability when comparing to chitosan-based membranes without Mg2+. The results obtained evidenced promising performance in biomedical applications for the new biopolymeric supports that are based on chitosan, ALP, and metal ions.