High Complex Concentrations Research Articles

In silico analysis of the melamine structural analogues interaction with calcium-sensing receptor: A potential for nephrotoxicity

In recent years, melamine, and its structural analogues, as adulterants in various food products including protein supplements,have been widely studied for their nephrotoxic effects. Previous research has presented evidence that certain small molecules can alter the calcium-sensing receptor (CaSR) function, contributing to nephrotoxicity. Melamine, for example, has been observed in in vitro settings to interact with the allosteric binding site of CaSR, resulting in uncontrolled CaSR activation. This activation results in the production of reactive oxygen species, which eventually causes kidney cell apoptosis and/or necrosis. The present research used the in silico molecular modelling to evaluate the CaSR binding profilesof four common adulterants in protein supplements: melamine, cyanuric acid, uric acid, and melamine cyanurate. Using Schrödinger’s Maestro docking software (version 13.2.128), the docking studies coupled a noncovalent extra precision mode with the molecular mechanics-generalized born surface area (MM-GBSA) simulation for enhanced binding affinity prediction accuracy. This study identified that cyanuric acid, uric acid, and melamine cyanurate have greater CaSR binding affinities than melamine. Interestingly, melamine cyanurate had the highest binding potential to CaSR. Previous animal studies have reported high concentrations of melamine cyanurate complex in rat kidneys following melamine administration. These findings demonstrate a molecular explanation melamine cyanurate complex-induced nephrotoxicity. This research offers new insight regarding the probable mechanism through which melamine, its analogues, and complexes may cause nephrotoxicity.

Fibrinolytic Dysfunction and Endotheliopathy After Major Thermal Injury: Considerations Needed for New Approaches to Burn Shock Resuscitation.

In recent years, it has become apparent that fibrinolytic dysfunction and endotheliopathy develop in up to 40% of patients during the first hours following thermal injury and are associated with poor outcomes and increased resuscitation requirements. Rapidly following burn injury, the fibrinolytic system is activated, with activation generally greater with increased severity of injury. Very high plasma concentrations of plasmin-antiplasmin complex (marker of activation), have been associated with mortality. Patients display hyperfibrinolytic, physiologic/normal or hypofibrinolytic/fibrinolytic shutdown phenotypes, as assessed by viscoelastic assay. Phenotypes change in over 50% of patients during the acute burn resuscitation period, with some patterns (maladaptive) associated with increased mortality risk and others (adaptive, trending toward the physiologic phenotype) associated with survival. Endotheliopathy, as reflected in elevated plasma concentrations of syndecan-1 has also been associated with increased mortality. Here we review the incidence and effects of these responses after burn injury and explore mechanisms and potential interactions with the early inflammatory response. Available data from burn and non-burn trauma suggest that the fibrinolytic, endothelial, and inflammatory systems interact extensively and that dysregulation in one may exacerbate dysregulation in the others. This raises the possibility that successful treatment of one may favorably impact the others.

Actinomycetes as a Possible Source of Bioremediation of Heavy Metal Cadmium from Contaminated Soil

Annually, a significant volume of chemicals, encompassing fertilizers and pesticides, is administered to agricultural soils. Using pesticides and fertilizers, agricultural practices contribute to heavy metal Cadmium (Cd), Copper (Cu), Lead (Pb) and Zinc (Zn) pollution. Heavy metals and pesticides are high at the peak of ecological contaminants, presence of this has introduced grave risks to the health of the population and agronomics. Among heavy metals, cadmium (Cd) is recognized for its high mobility in various environmental settings. Cd has a deleterious effect on plant phenotypic, cytotoxicity (e.g., lowering chlorophyll concentration and limiting photosynthetic effectiveness), and metabolic activities (e.g., chlorosis and necrosis). Microbial bioremediation by using microorganisms is one of the secure, pure, cost operative and eco-friendly technology for decontaminating polluting sites as compared to physical and chemical techniques. Among microbes, Actinobacteria hold a paramount position, serving as key players in numerous biological processes, utilize toxins as carbon source and turn into high concentrations of pesticides, chemical complexes and heavy metals into commercially viable antibiotics, enzymes, proteins, and plant growth promoting hormones. This study is an effort to explore the potent cadmium resistance actinomycetes to reduce cadmium levels to enhance degradation. For this purpose, 53 actinomycetes strains were tested for heavy metal resistance and tolerance to Cadmium against different concentrations. After secondary screening Four potent isolate have the potential to grow at 1000 mg/L concentration of Cadmium in the medium. When they are able to grow on heavy metal containing media it could be beneficial for reduction and elimination of toxic metals from contaminated environment. When it comes to achieving a suitable level of metal tolerance, this potent powerful actinomycetes strain Streptomyces pactum have been identified to be promising.

Formation of Tubular Aluminum Oxides by Local Electrochemical Anodization in Organic Electrolytes and Their Anti-Reflection Properties

Research has been carried out on the formation of tubular aluminum oxides by local electrochemical anodization in aqueous solutions of organic acids such as formic, citric, tartaric, malic and others. Self-ordered nanostructures formed this way can be used in the manufacture of various optical devices. Tubular aluminum oxides formed by local electrochemical anodization in organic acids have a high concentration of anionic complexes containing carbon atoms over 10 at.%. Studies of reflection spectra showed effective anti-reflection properties of films with a specular reflection coefficient of 0.7–1.4 %.

Performance and mechanism of Al, N co-doped carbon/nano-TiO2 photocatalytic oxidation for the removal of ammonia nitrogen and Ni/Co complexes from ternary precursor wastewater

The process of producing ternary precursors for new lithium batteries produces industrial wastewater containing high concentrations of ammonia nitrogen and metal ammonia complexes, which requires strict treatment. In this study, a simple and efficient photocatalyst (Al, N co-doped carbon/nano-TiO2) with excellent adsorption and photocatalytic properties was developed. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), N2 adsorption–desorption test, UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), which indicated that the catalyst had excellent specific surface area and strong light absorption properties. In addition, the performance of photocatalytic treatment of ternary precursor wastewater was investigated by varying the amount of Al doping, the loading of nano-TiO2, the amount of catalyst input, changing the adsorption and photocatalytic time. The results suggested that the 3.0 g/L of Al, N co-doped carbon/nano-TiO2 composite photocatalyst achieved 91.45% degradation efficiency of ammonia nitrogen and the removal efficiency of nickel and cobalt was 99.11% and 98.34%, respectively. EDS and XPS analyses showed that ammonia nitrogen pollutants in the wastewater were eventually degraded to nitrogen and nitrogen oxides, with nickel and cobalt adsorbed on the catalyst surface in the form of Ni2+ and Co2+.

Preparation of high complex concentration emulsion stabilized by soy protein/dextran sulfate composite particles.

Soy protein isolate (SPI) could be used as an emulsifier to stabilize emulsions, while SPI is unstable under low acidic conditions. The stable composite particles of SPI and dextran sulfate (DS) could be formed by the electrostatic interaction at the pH was 3.5. And the SPI/DS composite particles were used to prepare the high complex concentration emulsion. The stabilization properties of high complex concentration emulsion were investigated. Compared to uncompounded SPI, the particle size of SPI/DS composite particles was smaller at 1.52 μm, and the absolute value of the potential increased to 19.9 mV when the mass ratio of SPI to DS was 1:1 and the pH was 3.5. With the DS ratio increased, the solubility of the composite particles increased to 14.44 times of the untreated protein at pH 3.5, while the surface hydrophobicity decreased. Electrostatic interactions and hydrogen bonds were the main forces between SPI and DS, and DS was electrostatically adsorbed on the surface of SPI. The emulsion stability significantly enhanced with the increase of complex concentration (38.88 times higher than at 1% concentration), the emulsion average droplet size was the lowest (9.64 μm), and the absolute value of potential was the highest (46.67 mV) when the mass ratio of SPI to DS was 1:1 and the complex concentration of 8%. The stability of the emulsion against freezing was improved. The SPI/DS complex has high solubility and stability under low acidic conditions, and the SPI/DS complex' emulsion has a well stability. This article is protected by copyright. All rights reserved.

Autoimmunity Is a Significant Feature of Idiopathic Pulmonary Arterial Hypertension.

Rationale: Autoimmunity is believed to play a role in idiopathic pulmonary arterial hypertension (IPAH). It is not clear whether this is causative or a bystander of disease and if it carries any prognostic or treatment significance. Objectives: To study autoimmunity in IPAH using a large cross-sectional cohort. Methods: Assessment of the circulating immune cell phenotype was undertaken using flow cytometry, and the profile of serum immunoglobulins was generated using a standardized multiplex array of 19 clinically validated autoantibodies in 473 cases and 946 control subjects. Additional glutathione S-transferase fusion array and ELISA data were used to identify a serum autoantibody to BMPR2 (bone morphogenetic protein receptor type 2). Clustering analyses and clinical correlations were used to determine associations between immunogenicity and clinical outcomes. Measurements and Main Results: Flow cytometric immune profiling demonstrates that IPAH is associated with an altered humoral immune response in addition to raised IgG3. Multiplexed autoantibodies were significantly raised in IPAH, and clustering demonstrated three distinct clusters: "high autoantibody," "low autoantibody," and a small "intermediate" cluster exhibiting high concentrations of ribonucleic protein complex. The high-autoantibody cluster had worse hemodynamics but improved survival. A small subset of patients demonstrated immunoglobulin reactivity to BMPR2. Conclusions: This study establishes aberrant immune regulation and presence of autoantibodies as key features in the profile of a significant proportion of patients with IPAH and is associated with clinical outcomes.

The effect of annealing on photoluminescence from defects in ammonothermal GaN

Ammonothermal GaN samples with the concentration of free electrons of 1018 and 1019 cm−3 were annealed in a wide range of temperatures (Tann = 300–1400 °C) under atmospheric N2 pressure and under ultra-high N2 pressure conditions to avoid the GaN decomposition. Photoluminescence (PL) studies reveal the YL2 band with a maximum at 2.3 eV before annealing and two new PL bands after annealing at Tann > 600 °C: the OL3 band with a maximum at 2.1 eV and the RL4 band with a maximum at 1.6–1.7 eV. The ammonothermal GaN samples have high concentrations of complexes containing gallium vacancy (VGa), hydrogen, and oxygen. The first-principles calculations suggest that the VGa-3Hi complex is the origin of the YL2 band, while the VGa-3ON complex is responsible for the RL4 band.

The Effects of Mung Bean Peptide and Its’ Complexes on the Treatment of Lead Poisoning

Objective. To investigate the effects of mung bean peptide and its’ complexes on promoting lead excretion and neuroprotection of zebrafish. Methods. The lead poisoning models of zebrafish were established by lead acetate solution; the models were treated with high and low concentrations (58.3 and 175 μg/mL) of mung bean peptides, with high, medium, and low concentrations (27.8, 83.3, and 250 μg/mL) of mung bean peptide complexes, separately. The effects of the mung bean peptide complexes on the lead content, axonal fluorescence intensity, and peripheral motor nerve length changes were identified in the zebrafish model, and the effects of mung bean peptide and its’ complexes on zebrafish's lead excretion, axonal protection rate, and peripheral movement promotion rate of nerve regeneration were calculated. Results. The effects of high concentration of mung bean peptide (175 μg/mL) in promoting lead excretion was 29% ( p < 0.05 ), and the effect of high concentration of mung bean peptide complexes (250 μg/mL) in promoting lead excretion was 30% ( p < 0.05 ). The other concentrations of mung bean peptide and its’ complex groups did not show a noticeable lead excretion effect. The protective effects of mung bean peptide at concentrations of 58.3 and 175 μg/mL against zebrafish axonal injury were 98% and 101% ( p < 0.01 ), and the peripheral nerve regeneration promotion effects were 29% ( p > 0.05 ) and 42% ( p < 0.05 ), respectively. The protective effects of mung bean peptide complexes at concentrations of 27.8, 83.3, and 250 μg/mL against zebrafish axonal injury were 85%, 78%, and 93% ( p < 0.01 ); peripheral nerve regeneration promotion rates were 46%, 50%, and 50% ( p < 0.05 ). Conclusion. The mung bean peptide and its’ complexes can effectively promote the discharge of lead in the zebrafish lead poisoning and have protective and regeneration effects on zebrafish nerves.

Scavenging capacity and cytotoxicity of new Ru(II)-diphosphine/α-amino acid complexes

Reaction of α-amino acids (HL) with the precursor cis-[RuCl2(dppe)2] [HL = tyrosine (Tyr) or serine (Ser); dppe = 1,2-bis(diphenylphosphino)ethane] afforded the complexes [Ru(L−)(dppe)2]Cl {[Ru(Tyr-)(dppe)2]Cl (1) and [Ru(Ser-)(dppe)2]Cl (2)}. The new ruthenium complexes, with formulae [Ru(Tyr-)(dppe)2]Cl (1) and [Ru(Ser-)(dppe)2]Cl (2) were synthesized and characterized on the basis of elemental analysis, molar conductivity, IR/UV–Vis and 31P{1H} NMR spectra. The in vitro cytotoxicities of the complexes against the MDA-MB-231 (breast adenocarcinoma) cell line were determined by the MTT assay. Complexes (1) and (2) show good cytotoxicity profiles against the MDA-MB-231 cell line with IC50 values of 2.05 ± 0.71 μM and 5.64 ± 0.72 μM, respectively, which are in the same order of values obtained for the metallodrug cisplatin (2.44 ± 0.20 μM) in the same assay. The selectivity indexes were significant for both complexes, showing lower cytotoxicity activity against the non-tumor breast cell line MCF-10A, with SI of 5.0 and 3.2, respectively. In addition, the lipophilicities of these complexes were determined and their interactions with human serum albumin (HSA) protein were investigated by fluorescence. The lipophilicities of the complexes suggest that this property has a significant effect on their cytotoxicity and the interaction measurements of the complexes with HSA indicate that the static fluorescence quenching mechanism is the main one involved in the formation of (1)-HSA and (2)-HSA adducts. Moreover, Van der Waalś interactions and hydrogen bonds in (1)-HSA and electrostatic interaction in (2)-HSA are the predominant intermolecular forces between the complexes and the biomolecule. Furthermore, the antioxidant activity of the complexes was determined using the superoxide radical scavenging method, in vitro. Complex (1) was found to present a higher antioxidative activity, showing to be better than the standard antioxidant, vitamin C. In vivo toxicity assessment on zebrafish embryos showed that although the higher concentration of complex (1) has caused lethality of embryos, the effects of the concentration equivalent to the IC50 of complex (1) and cisplatin were similar in the hatching rate, mortality rate and morphological changes, showing a potential of complex (1) as a new anticancer agent.

Size-dependent strengthening in multi-principal element, face-centered cubic alloys

Multi-principal element (MPE) alloys, sometimes also known as high entropy, complex concentration or multicomponent alloys, have attracted significant attention due to their remarkable mechanical properties, especially face-centered cubic (fcc) CrCoNi-based alloys. In this study, the size effect and strain rate dependence of the strength of equiatomic ternary (CrCoNi), quaternary (CrFeCoNi), and quinary MPE (CrMnFeCoNi) alloys were investigated using in situ strain rate jump (SRJ) micropillar compression tests. No obvious correlation is found between size dependence of strength and the number of elements in these alloys, but an inverse relation is observed between size effect exponent and the Peierls' stress. The single arm source strengthening model was successfully applied on the entire range of samples from the fcc pure elements to fcc equiatomic MPE alloys. Moreover, the activation volumes (~10 b3 to ~100 b3) are consistent among the MPE alloys, indicating the main deformation mechanism is similar in these alloys: dislocation-solute and dislocation-dislocation interactions.

Secrets, puzzles and mysteries of macroamylasemia

Physiological features of amylase synthesis and excretion are considered in the article, presence of other sources of amylase synthesis different from pancreas and salivary glands is emphasized. Definitions of hyperenzymemia and macroamylasemia (MAE) are given. MAE is a state characterized by presence of circulating complexes of normal serum amylase with protein or carbohydrates in blood. There are 3 types of MAE: first — classical (constant hyperamylasemia, decreased amylase level in urine, high blood concentration of macroamylase complexes); second — hyperamylasemia with slightly decreased amylase activity in urine, macroamylase/normal amylase ratio is less than in the first type; third — normal blood and urine amylase activity, low macroamylase/normal amylase ratio. Pathogenesis is explained by connection of blood amylase and acute phase protein in different inflammatory, infectious diseases, malabsorption. MAE clinical manifestations could be absent, sometimes abdominal pain is possible. Hyperamylasemia and reduced urine amylase activity are typical. MAE diagnostics means determination of macroamylase complexes in blood (chromatography, calculation of the clearance ratio of amylase and creatinine). The article presents clinical cases describing extra-pancreatic MAE in women with malignant ovarian lesions. The question of expediency of thorough diagnostic examination in asymptomatic MAE is raised, which may turn out to be a symptom of cancer. The lack of specific treatment for MAE is emphasized.

Fabrication and characterization of emulsions stabilized by tannic acid-wheat starch complexes

Soybean oil-based emulsions stabilized by tannic acid (TA) and wheat starch (WS) complexes were prepared via a simple high-intensity ultrasound emulsification technique. The effects of mass ratio of TA/WS (0.005–0.75) and WS concentration (0.25%, 0.5% and 1.0%) on TA/WS complexes and emulsions were investigated. As the mass ratio increased, TA and WS could gradually form soluble and insoluble complexes, and their hydrophobicity also improved. Consequently, the tendency of the particle size of emulsions to decrease first and then increase appeared with the increasing mass ratio, mainly due to the changes in the contents, size and hydrophobicity of the complex emulsifier. Additionally, the emulsifying capacity of TA/WS complexes improved with increasing concentration of complexes. Moreover, the creaming was inhibited at a high mass ratio or high complex concentration due to the formation of a thick interfacial network around oil droplets or obtention of smaller-sized droplets. Emulsion gel was formed due to TA cross-linked WS on the interface within different oil droplets, and the strength of the gel increased with the mass ratio due to increasing amounts of complexes being absorbed on the interface. When the mass ratio and WS concentration were no less than 0.05 and 0.5%, respectively, emulsions had better oxidative stability. The complexes also had high resistance against droplet coalescence. This study demonstrated that TA/WS complexes could be employed as an emulsifier to improve the oxidative stability of O/W emulsions and that easily oxidized, oil-soluble nutrients or medicines could be protected and delivered through these emulsion systems.

Antibody Dependent Enhancement of Acinetobacter baumannii Infection in a Mouse Pneumonia Model.

Acinetobacter baumannii has become a pathogen of increasing medical importance because of the emergence of multidrug-resistant strains and the high rate of mortality of infected patients. Promising animal study results have been reported recently with active and passive immunization against A. baumannii virulence factors. In the present study, a monoclonal IgG3 antibody, 8E3, was developed with specificity for the K2 capsular polysaccharide of A. baumannii, and its therapeutic potential was assessed. 8E3 enhanced macrophage-mediated bactericidal activity against the A. baumannii clinical strain AB899. However, 8E3 treatment (passive immunization) of AB899-infected mice led to a substantial increase in mortality and to substantial increases in bacterial load in blood, lung, and in splenic samples. In vitro investigations showed a large binding capacity in the supernatant of bacterial cultures, suggesting that shed capsule components act as a binding sink for 8E3. Investigations of 8E3 pharmacokinetics in mice demonstrated that unbound concentrations of the antibody dropped below detection limits within 24 hours after a 200 mg/kg dose. However, total concentrations of antibody declined slowly, with an apparent terminal half-life (t 1/2) of 6.7-8.0 days, suggesting that the vast majority of 8E3 in blood is bound (e.g., with soluble capsule components in blood). We hypothesize that high concentrations of 8E3-capsule immune complexes act to inhibit bacterial clearance in vivo. To the best of our knowledge, this is the first demonstration of antibody-dependent enhancement of A. baumannii infection, and these observations highlight the complexity of antibody-based therapy for A. baumannii infections.

Insights into Second-Sphere Effects on Redox Potentials, Spectroscopic Properties, and Superoxide Dismutase Activity of Manganese Complexes with Schiff-Base Ligands.

Six Mn-Schiff base complexes, [Mn(X-salpn)]0/+ (salpn = 1,3-bis(sal-ic-ylidenamino)propane, X = H [1], 5-Cl [2], 2,5-F2 [3], 3,5-Cl2 [4], 5-NO2 [5], 3,5-(NO2)2 [6]), were synthesized and characterized in solution, and second-sphere effects on their electrochemical and spectroscopic properties were analyzed. The six complexes catalyze the dismutation of superoxide with catalytic rate constants in the range 0.65 to 1.54 × 106 M–1 s–1 obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutases assay, in aqueous medium of pH 7.8. In solution, these compounds possess two labile solvent molecules in the axial positions favoring coordination of the highly nucleophilic O2•– to the metal center. Even complex 5, [Mn(5-(NO2)salpn) (OAc) (H2O)], with an axial acetate in the solid state, behaves as a 1:1 electrolyte in methanolic solution. Electron paramagnetic resonance and UV–vis monitoring of the reaction of [Mn(X-salpn)]0/+ with KO2 demonstrates that in diluted solutions these complexes behave as catalysts supporting several additions of excess O2•–, but at high complex concentrations (≥0.75 mM) catalyst self-inhibition occurs by the formation of a catalytically inactive dimer. The correlation of spectroscopic, electrochemical, and kinetics data suggest that second-sphere effects control the oxidation states of Mn involved in the O2•– dismutation cycle catalyzed by complexes 1–6 and modulate the strength of the Mn-substrate adduct for electron-transfer through an inner-sphere mechanism.

Changes in human sperm motility characteristics in the presence of protein-peptide complex

The study objectiveis to examine the changes in motility of human spermatozoa under the effect of a protein-peptide complex extracted from cattle testes (Bos taurus).Materials and methods. The protein-peptide complex was extracted from testes tissue obtained during butchering of cattle at meat processing plants of the Moscow Region. Human spermatozoa were obtained from the ejaculate in the usual way. From the ejaculate sample, 1 ml was collected for the experiment and control. The protein-peptide complex was added to a test tube in concentrations of 10–8, 10–9, and 10–12 mg/ml. For every concentration, 10–12 experiments were performed. General and active motility were evaluated after 30 min, 1 and 3 hours of incubation at room temperature.Results and conclusion. The experiments have shown that in the presence of the protein-peptide complex, spermatozoa motility increased by 10–30 % relative to the initial value at 30 minutes, and this change persisted for 3 hours of observation. The change depended on the complex concentration: the largest increase was observed at 10–12 mg/ml. Higher complex concentrations did not have a positive effect on spermatozoa motility.

Do constructed wetlands remove metals or increase metal bioavailability?

The H-02 wetland was constructed to treat building process water and storm runoff water from the Tritium Processing Facility on the Department of Energy's Savannah River Site (Aiken, SC). Monthly monitoring of copper (Cu) and zinc (Zn) concentrations and water quality parameters in surface waters continued from 2014 to 2016. Metal speciation was modeled at each sampling occasion. Total Cu and Zn concentrations released to the effluent stream were below the NPDES limit, and the average removal efficiency was 65.9% for Cu and 71.1% for Zn. The metal-removal processes were found out to be seasonally regulated by sulfur cycling indicated by laboratory and model results. High temperature, adequate labile organic matter, and anaerobic conditions during the warm months (February to August) favored sulfate reduction that produced sulfide minerals to significantly remove metals. However, the dominant reaction in sulfur cycling shifted to sulfide oxidation during the cool months (September to next March). High concentrations of metal-organic complexes were observed, especially colloidal complexes of metal and fulvic acid (FA), demonstrating adsorption to organic matter became the primary process for metal removal. Meanwhile, the accumulation of metal-FA complexes in the wetland system will cause negative effects to the surrounding environment as they are biologically reactive, highly bioavailable, and can be easily taken up and transferred to ecosystems by trophic exchange.

Does dentifrice provide the necessary saturation of ions in oral fluids to favour remineralisation?

Background ― Changes in the molecular composition of mixed human saliva using endogenous and exogenous methods of caries prevention were studied and the duration of these changes in relation to the initial state of the oral fluid was determined. Material and Methods ― In total, 200 European healthy, addiction-free, university-educated males and females, aged 22–30 were recruited for the study. Participants collected their mixed saliva samples after the use of a multi-mineral toothpaste (exogenous prevention) and after three days of taking a calcium glycerophosphate tablet (endogenous prevention). In the first stage of the study, samples of mixed saliva were analysed by infrared (IR) lab spectrometer and equipment of infrared microspectroscopy beamline at the Australian Synchrotron (Victoria, Australia) was used in the second stage of study. Results ― Based on the experimental data obtained by IR-spectroscopy technique, the mineral/organic and carbon/phosphate ratios were calculated. The changes in the organic mineral balance of the oral cavity induced by these two preventive methods were analysed. The statistical significance of the results for the confidence level of p is indicated. The data shows that changes in the molecular composition of mixed saliva when using an exogenous method of caries prevention only provides a short-term effect, continuing for the first 30 minutes after the preceding prevention. Moreover, calcium glycerophosphate tablets can change the organic-mineral balance in mixed saliva, increasing the content of mineral groups and complexes. The content of endogenous, biologically accessible phosphate groups and complexes in the mixed saliva exceeds by approximately 12% that of the mixed saliva before the use of the prevention agents. Conclusion ― Use of calcium glycerophosphate tablets in combination with brushing (a combination of endogenous and exogenous prevention methods) leads to the long-term presence of high concentrations of ions, mineral complexes and groups (phosphates) in the oral fluid.

Interaction of DNA with water soluble complex of Nickle and formation of DNA cross-links

Interaction of double stranded DNA with bulky and hydrophobic Salen type Schiff base complex: [N, N′ Bis [3- tert-butyl-5-[triphenyl-phosphonium – methyl] - salicylidene] 1,2 ethylene-diamine nickel(III) acetate (refer to Ni Salen complex) was extensively investigated using the spectroscopic techniques and gel electrophoresis. Absorption titration experiment showed the hypochromic effect and the significant red shift of the complex absorption. In competition experiments with ethidium bromide (EB), Ni Salen complex exhibited non-competitive binding at high concentrations. UV-vis absorption and fluorescence emission data agreed on a binding constant of (1.64 ± 0.01) μM−1, thereby showing the strong interaction of the complex with DNA; also, a binding site size of 2.33 ± 0.01 base pairs per complex was achieved.Thermal denaturation experiment showed that Tm of calf thymus-DNA was increased by approximately 10 °C at a molar ratio of the dye/base of 0.2. The CD spectra of DNA exhibited an increase in both positive and negative peaks without any shift in the position of bands upon addition of the complex. The amplitude of the LD spectra of DNA was decreased in the presence of the complex. Reduced linear dichroism (LDred) revealed that the transition moment of complex was parallel to the DNA helix axis. Gel electrophoresis experiments confirmed that Ni Salen complex had no nuclease/DNA cleaving activity; also, DNA-DNA cross links were formed at high concentrations of complex, leading to the aggregation of DNA.

Biota and geomorphic processes as key environmental factors controlling soil formation at Elephant Point, Maritime Antarctica

We examined the main soil forming factors affecting the soil composition, soil properties and the associated soil-forming processes at Elephant Point, a small ice-free environment in the South Shetland Islands, Maritime Antarctica. For this purpose, we collected twenty soil samples from each of ten different sites distributed along a linear transect running from the coast to the front of the Rotch Dome glacier. The samples were obtained from surface layers (0–10cm) and at depth (40–50cm), although collection was limited in the moraine area by the permafrost table. We determined pH, electrical conductivity, size particle distribution, total organic carbon, total nitrogen and total concentrations of Al, Fe, Ca and P, for physical and chemical characterization of the samples. We also analysed the samples to determine the bioavailability of nutrients and Fe, Al and P partitioning and finally examined them by isotopic (δ15N) and X-ray diffraction (XRD) analysis. The results of the analyses revealed two clear geochemical environments corresponding to the two most extensive geomorphological units in this peninsula: moraine and marine terraces. Soils from the moraine were characterized by alkaline reaction and high quantity of minerals with a low degree of crystallinity, whereas soils from the marine terraces showed acid reaction, high concentration of organometallic complexes and a high diversity of phosphate minerals (taranakite, minyulite, struvite, hydroxylapatite and leucophosphite), which seem to be generated by phosphatization of faecal matter deposited by seabirds and seals. Consequently, biota activity is the most relevant soil differentiating factor in the marine terraces, which add organic matter and activate geochemical cycles. On the other hand, geomorphic processes strongly affected by physical weathering processes such as glacial abrasion (by grinding process), frost shattering, and wind abrasion are the main soil-forming factors in moraine. These forces break up the parent material, transform it and translocate the products formed.