Sodium Maleate Research Articles

Interaction of Cyclodextrins with Amphiphilic Alternating Cooligomers Possessing the Dense Triazole Backbone.

The interaction of cyclodextrins (CDs) with structure-controlled polymers is expected to provide significant insights into macromolecular recognition. However, the interaction of CDs with structure-controlled polymers has been an underexamined issue of investigation. Herein, alternating amphiphilic cooligomers (oligoCnAH, where n denotes the carbon number of alkyl groups; n = 4, 8, and 12) were synthesized by copper(I)-catalyzed azide-alkyne cycloaddition polymerization of heterodimers of 4-azido-5-hexynoic acid (AH) derivatives carrying N-alkylamide and t-butyl (tBu) ester side chains, followed by hydrolysis of the tBu ester, to study the interaction of CDs with oligoCnAH by 1H NMR, nuclear Overhauser effect spectroscopy, and pulse-field-gradient spin-echo NMR. These NMR studies indicated that αCD interacted with oligoC4AH, αCD and βCD interacted with oligoC8AH, and all CDs interacted with oligoC12AH. Based on the equilibrium models proposed, the binding constants were evaluated for the binary mixtures, which showed interaction. Comparing the interactions of the CDs/oligoC12AH binary mixtures with those of the binary mixtures of CDs and alternating copolymers of sodium maleate and dodecyl vinyl ether (polyC12M), it is concluded that oligoC12AH forms less stable micelles than does polyC12M presumably because of the lower molecular weight, the hydrophilic amide groups in the side chain, and the longer interval between neighboring C12 groups in oligoC12AH.

Tobramycin Reduces Pulmonary Toxicity of Polymyxin B via Inhibiting the Megalin-Mediated Drug Uptake in the Human Lung Epithelial Cells.

Accumulation of polymyxins in the lung epithelial cells can lead to increased mitochondrial oxidative stress and pulmonary toxicity. Aminoglycosides and polymyxins are used, via intravenous and pulmonary delivery, against multidrug-resistant Gram-negative pathogens. Our recent in vitro and animal studies demonstrated that the co-administration of polymyxins with aminoglycosides decreases polymyxin-induced pulmonary toxicity. The aim of this study was to investigate the in vitro transport and uptake of polymyxin B and tobramycin in human lung epithelial Calu-3 cells and the mechanism of reduced pulmonary toxicity resulting from this combination. Transport, intracellular localization, and accumulation of polymyxin B and tobramycin were investigated using doses of 30 mg/L polymyxin B, 70 mg/L tobramycin, and the combination of both. Adding tobramycin significantly (p < 0.05) decreased the polymyxin B-induced cytotoxicity in Calu-3 cells. The combination treatment significantly reduced the transport and uptake of polymyxin B and tobramycin in Calu-3 cells, compared to each drug alone, which supported the reduced pulmonary toxicity. We hypothesized that cellular uptake of polymyxin B and tobramycin shared a common transporter, megalin. We further investigated the megalin expression of Calu-3 cells using confocal microscopy and evaluated megalin activity using a megalin substrate, FITC-BSA, and a megalin inhibitor, sodium maleate. Both polymyxin B and tobramycin significantly inhibited FITC-BSA uptake by Calu-3 cells in a concentration-dependent manner. Sodium maleate substantially inhibited polymyxin B and tobramycin transport and cellular accumulation in the Calu-3 cell monolayer. Our study demonstrated that the significantly reduced uptake of polymyxin B and tobramycin in Calu-3 cells is attributed to the mechanism of action that determines that polymyxin B and tobramycin share a common transporter, megalin.

Effect of adsorption-catalytic deformation and partial deactivation on the determination of the absolute activity of a liquid phase hydrogenation catalyst

Objectives. To take into account the change in the number of active sites during the adsorptioncatalytic deformation and deactivation of a catalyst surface by means of a catalytic poison when calculating the turnover frequency (TOF) of a hydrogenation catalyst.Methods. The activity was determined by a static method, using a titanium reactor having a volume of 400 mL, an experimental temperature controlled using a liquid thermostat with an accuracy of 0.5 K, with a paddle stirrer rotation speed of 3600 rpm and system hydrogen pressure equal to atmospheric. The consumption of hydrogen used to reduce the model compound was taken into account via the volumetric method. The heats of hydrogen adsorption were determined using a reaction calorimeter with an operating mode close to that of a chemical reactor. After measuring the specific surface area using low temperature nitrogen adsorption, the results were processed using Brunauer–Emmett–Teller theory approximations. Deactivation was carried out by introducing dosed amounts of catalytic poison into the system in titration mode.Results. A kinetic experiment for the reduction of a multiple carbon bond in a sodium maleate molecule using aqueous solutions of sodium hydroxide with additions of monohydric aliphatic alcohols as solvents under conditions of partial deactivation of the catalyst was carried out. The obtained values of heats of hydrogen adsorption on skeletal nickel in the course of the experiment are given. The described approach is used to calculate TOF values taking into account changes in the number of active surface sites during the course of a catalytic reaction and upon the introduction of a deactivating agent. A refined equation for the correct calculation of TOF is proposed along with its mathematical justification. The results of TOF calculations under various assumptions for a number of catalytic systems are shown.Conclusions. When calculating absolute activity values, a change in the number of active sites has a significant effect on the obtained values. The physical meaning of a number of constants in the proposed equation relates the activity of the catalyst to the distribution of hydrogen on its surface in terms of heats of adsorption.

Room‐Temperature Phosphorescent Tough Hydrogels Based on Ionically Crosslinked Nonaromatic Polymers

AbstractOrganic photoluminescent materials exhibiting room‐temperature phosphorescence (RTP) have attracted widespread attention. However, most of them can emit phosphorescence only in the solid state, which strongly limits their applications. Herein, a type of phosphorescent hydrogel with excellent mechanical properties is prepared by immersing an as‐prepared poly(vinyl alcohol) (PVA) hydrogel in a poly(sodium maleate) solution and then in a CaCl2 solution, followed by drying under stretching at 90 °C and finally soaking it in deionized water until equilibrium swelling to produce poly(vinyl alcohol)/poly(calcium maleate)‐DS ( PVA/PMACa‐DS) hydrogels. Such hydrogels exhibit excellent mechanical properties, showing tensile strengths up to 15 MPa, due to the presence of strong hydrogen bonding and especially ionic bonding. The PVA/PMACa‐DS hydrogels emit varied phosphorescence emission colors from blue to yellow‐green upon excitation with 312–400 nm light, with a maximum lifetime of 13.4 ms. Experiments and theoretical calculations demonstrate that ionic crosslinking between Ca2+ and nonconventional chromophores prevents the contact of the nonconventional chromophores with water molecules and hence restricts nonradiative decay, leading to RTP emission. This work provides a reliable strategy for designing RTP hydrogels with excellent mechanical properties based on nonaromatic polymers for emerging applications.

Does It Bind? A Method to Determine the Affinity of Calcium and Magnesium Ions for Polymers Using 1H NMR Spectroscopy.

The binding of calcium and magnesium ions (M2+) by polymers and other macromolecules in aqueous solution is ubiquitous across chemistry and biology. At present, it is difficult to assess the binding affinity of macromolecules for M2+ without recourse to potentiometric titrations and/or isothermal titration calorimetry. Both of these techniques require specialized equipment, and the measurements can be difficult to perform and interpret. Here, we present a new method based on 1H NMR chemical shift imaging (CSI) that enables the binding affinity of polymers to be assessed in a single experiment on standard high-field NMR equipment. In our method, M2+ acetate salt is weighed into a standard 5 mm NMR tube and a solution of polymer layered on top. Dissolution and diffusion of the salt carry the M2+ and acetate ions up through the solution. The concentrations of acetate, [Ac], and free (unbound) M2+, [M2+]f, are measured at different positions along the sample by CSI. Binding of M2+ to the polymer reduces [M2+]f and hinders the upward diffusion of M2+. A discrepancy is thus observed between [Ac] and [M2+]f from which the binding affinity of the polymer can be assessed. For systems which form insoluble complexes with M2+, such as sodium polyacrylate or carboxylate-functionalized nanocellulose (CNC), we can determine the concentration of M2+ at which the polymer will precipitate. We can also predict [M2+]f when a solution of polymer is mixed homogeneously with M2+ salt. We assess the binding properties of sodium polyacrylate, alginate, polystyrene sulfonate, CNC, polyethyleneimine, ethylenediamenetetraacetic acid, and maleate.

Characterization of potential probiotic strain, L. reuteri B2, and its microencapsulation using alginate-based biopolymers

In this study, Lactobacillus reuteri B2 was isolated from the feces of C57BL/6 mice and assessed on probiotic activity. L. reuteri B2 was identified by 16S rDNA sequencing, which the cell viability in acidic conditions at pH 2.0 was 64% after 2 h, and in the presents of 0.30% of the bile salts, after 6 h, was 37%. Antimicrobial assay with L. reuteri B2 showed maximum diameters against Klebsiela oxytoca J7 (12.5 ± 0.71 mm). We further hypothesized if L. reuteri B2 strain in the free form can survive all conditions in the gastrointestinal tract (GIT) then the utilization of the appropriate biomaterials would ameliorate its stability and viability in GIT. L. reuteri B2 was microencapsulated into sodium alginate-(Na-alg) and different content of Na-alg and sodium maleate (SM) beads. Characterization materials enveloped their thermal characteristics (TGA/DTA analysis) and structure using: scanning electron microscopy (SEM), FTIR, and particle size distribution. The high survival rate of L. reuteri B2 at low pH from 2.0 to 4.0 and in the presence of the bile salts, at concentrations up to 0.30%, was obtained. L. reuteri B2 showed strong antimicrobial activity and the best protection microencapsulated with Na-alg + SM in simulated gastric juices (SGJ).

ImmunoPET imaging of multiple myeloma with [68Ga]Ga-NOTA-Nb1053.

Multiple myeloma (MM) remains incurable and its diagnosis relies heavily on bone marrow aspiration and biopsy. CD38 is a glycoprotein highly specific for MM. Antibody therapeutics (e.g., daratumumab) targeting CD38 have shown encouraging efficacy in treating MM, either as a monotherapy agent or in combination with other regimens. However, efficient stratification of patients who might benefit from daratumumab therapy and timely monitoring of the therapeutic responses are still clinical challenges. This work aims to devise a CD38-targeted imaging strategy and assess its value in diagnosing MMs. By labeling a CD38-specific single domain antibody (Nb1053) with 68Ga (t1/2=1.1h), we developed a CD38-targeted immuno-positron emission tomography (immunoPET) imaging probe [68Ga]Ga-NOTA-Nb1053. The probe was developed with good radiochemical yield (> 50%), excellent radiochemical purity (> 99%), and immunoreactivity (> 95%). The diagnostic accuracy of the probe was thoroughly investigated in preclinical MM models. ImmunoPET imaging with [68Ga]Ga-NOTA-Nb1053 specifically depicted all the subcutaneous and orthotopic MM lesions, outperforming the traditional 18F-fluorodeoxyglucose PET and the nonspecific [68Ga]Ga-NOTA-NbGFP immunoPET. More importantly, daratumumab preloading significantly reduced [68Ga]Ga-NOTA-Nb1053 uptake in the disseminated bone lesions, indicating the overlapping targeting epitopes of [68Ga]Ga-NOTA-Nb1053 with that of daratumumab. Furthermore, premedication with sodium maleate or fructose significantly decreased kidney retention of [68Ga]Ga-NOTA-Nb1053 and improved the diagnostic value of the probe in lymphoma models. This work successfully developed a novel CD38-targeted immunoPET imaging approach that enabled precise visualization of CD38 and diagnosis of MMs. Upon clinical translation, [68Ga]Ga-NOTA-Nb1053 immunoPET may serve as a valuable CD38-targeted molecular imaging toolbox, facilitating early diagnosis of MM and precise assessment of the therapeutic responses.

Investigation of a Pharmacological Approach for Reduction of Renal Uptake of Radiolabeled ADAPT Scaffold Protein.

Albumin binding domain-Derived Affinity ProTeins (ADAPTs) are small (5 kDa) engineered scaffold proteins that are promising targeting agents for radionuclide-based imaging. A recent clinical study has demonstrated that radiolabeled ADAPTs can efficiently visualize human epidermal growth factor receptor 2 (HER2) expression in breast cancer using SPECT imaging. However, the use of ADAPTs directly labeled with radiometals for targeted radionuclide therapy is limited by their high reabsorption and prolonged retention of activity in kidneys. In this study, we investigated whether a co-injection of lysine or gelofusin, commonly used for reduction of renal uptake of radiolabeled peptides in clinics, would reduce the renal uptake of [99mTc]Tc(CO)3-ADAPT6 in NMRI mice. In order to better understand the mechanism behind the reabsorption of [99mTc]Tc(CO)3-ADAPT6, we included several compounds that act on various parts of the reabsorption system in kidneys. Administration of gelofusine, lysine, probenecid, furosemide, mannitol, or colchicine did not change the uptake of [99mTc]Tc(CO)3-ADAPT6 in kidneys. Sodium maleate reduced the uptake of [99mTc]Tc(CO)3-ADAPT6 to ca. 25% of the uptake in the control, a high dose of fructose (50 mmol/kg) reduced the uptake by ca. two-fold. However, a lower dose (20 mmol/kg) had no effect. These results indicate that common clinical strategies are not effective for reduction of kidney uptake of [99mTc]Tc(CO)3-ADAPT6 and that other strategies for reduction of activity uptake or retention in kidneys should be investigated for ADAPT6.

The Improvement of Polymer Structure Related to Radical Treatment of Alveolar Abcesses

Painful periapical manifestations are inflammatory responses of periapical connective tissue to pulpal irritants, when the exudative forces become hyperactive. From the point of view of tooth preservation, apical resection is a valuable procedure in avoiding early edentation, as it is a factual surgical method that comes to aid the conservative endodontic therapy. Polymers are chemical compounds (in most cases organic) with large molecules (macromolecules) obtained from the union of a molecular chain (catena) of a large number of monomers usually with identical structural units. In our research we evaluated the resistance to traction 9 test specimens for which the structure was aimed at the improvement of the self-polymerizable acrylic structure by adding sodium maleate co-polymers, namely maleic anhydride, whose structure was linked to the anti-microbial substances, of the thymol type with controlled release, versions with greater resistance, they found clinical applicability on 244 cases. An increased resistance to fracture was registered for the test specimens II, which unites polymer powder together with the sodium maleate co-polymer, in a ratio of 3 to 1 (F = 1030 and max = 37.73), test specimen III, which unites polymer powder together with the co- anhydride maleic polymer, in a ratio of 3 to 1 (F = 950 and max = 37.88), followed by the same combinations to which it was added the care antibacterial substance, thymol. An important role in the long term in the success of the apical resection, in addition to the applied surgical technique, accrues to the retrograde obturation material, which insures an optimal healing at the peri-apical level insuring the bony apposition at this level.

Combined effect of Cromolyn sodium and Chlorpheniramine Maleate in high fat diet induced obesity

BackgroundObesity is a major health problem worldwide and risk factor for various cardiovascular diseases. High-Fat Diet (HFD) induced obesity in rats was an effective model to evaluate anti-obesity activities of drugs. Cromolyn sodium described as a mast cell stabilizer and Chlorpheniramine maleate used as an antihistaminic and prevents allergic inflammation. They also decreased the release of inflammatory mediators from mast cells. Mast cells were found to involve directly in obesity and diabetes. ObjectiveThe aim of this study was to determine the impact of Cromolyn sodium and Chlorpheniramine Maleate alone and the combination therapy of both on HFD induced rats. Experimentthe experiment was designed by supplementing HFD to rats for 49 days to induce obesity. The obese rats were treated with different drugs individually and in combination. Serum lipid parameters and Liver function parameters were observed and found a change in lipoproteins along with increased body weight, the mRNA of leptin, adiponectin and resistin in visceral adipose tissue were determined by quantitative real time-PCR. ConclusionChronic administration of Cromolyn Sodium (50 mg/kg) and its combination with Chlorpheniramine Maleate at a sub maximal dose (5 mg/kg & 25 mg/kg) reversed all the parameters significantly than Chlorpheniramine (10 mg/kg) alone, which was altered due to HFD. The combination showed effects directly on adipokines of visceral tissue and found a suitable candidate in treatment of metabolic syndrome.

On the prevention of kidney uptake of radiolabeled DARPins

BackgroundDesigned ankyrin repeat proteins (DARPins) are small engineered scaffold proteins (14–18 kDa) that demonstrated promising tumor-targeting properties in preclinical studies. However, high renal accumulation of activity for DARPins labeled with residualizing labels is a limitation for targeted radionuclide therapy. A better understanding of the mechanisms behind the kidney uptake of DARPins could aid the development of strategies to reduce it. In this study, we have investigated whether the renal uptake of [99mTc]Tc(CO)3-G3 DARPin could be reduced by administration of compounds that act on various parts of the reabsorption system in the kidney.ResultsCo-injection of lysine or Gelofusine was not effective for the reduction of kidney uptake of [99mTc]Tc(CO)3-G3. Administration of sodium maleate before the injection of [99mTc]Tc(CO)3-G3 reduced the kidney-associated activity by 60.4 ± 10.3%, while administration of fructose reduced it by 46.9 ± 7.6% compared with the control. The decrease in the kidney uptake provided by sodium maleate was also observed for [99mTc]Tc(CO)3-9_29 DARPin. Preinjection of colchicine, probenecid, mannitol, or furosemide had no effect on the kidney uptake of [99mTc]Tc(CO)3-G3. Kidney autoradiography showed mainly cortical accumulation of activity for all studied groups.ConclusionCommon clinical strategies were not effective for the reduction of kidney uptake of [99mTc]Tc(CO)3-G3. Both fructose and maleate lower the cellular ATP level in the proximal tubule cells and their reduction of the kidney reuptake indicates the involvement of an ATP-driven uptake mechanism. The decrease provided by maleate for both G3 and 9_29 DARPins indicates that their uptake proceeds through a mechanism independent of DARPin structure and binding site composition.

Evaluating the mucoprotective effect of polydeoxyribonucleotide against indomethacin-induced gastropathy via the MAPK/NF-κB signaling pathway in rats

Non-steroidal anti-inflammatory drugs (NSAIDs) cause gastric mucosal damage and gastric ulceration. Among the most commonly used NSAIDs, indomethacin upregulates mucosal tumor necrosis factor-α, which activates nuclear factor-kappa B (NF-κB), and mitogen-activated protein kinases (MAPK) to induce various pro-inflammatory mediators. Polydeoxyribonucleotide (PDRN) is an adenosine A2A receptor agonist that exerts anti-inflammatory effects. In this study, we evaluated the efficacy of PDRN in the initial treatment of gastropathy against that of ecabet sodium and irsoglandin maleate, which are commonly used medications. The rats were administrated indomethacin once a day for 7 days after 24 h of fasting to induce gastropathy. Rats in the drug-treated groups were orally administrated 500 μl of distilled water containing the drug once daily for 7 days 1 h after indomethacin administration. Indomethacin administration caused mucosal damage and increased pro-inflammatory cytokine release. Both NF-κB and MAPK cascade factors were increased by indomethacin administration. PDRN therapy more potently suppressed the expressions of NF-κB and MAPK cascade factors compared to other drugs. The expression of cyclic adenosine-3′,5′-monophosphate was also increased by PDRN treatment in the indomethacin-induced gastropathy rats. These changes led to a reduction in pro-inflammatory cytokines and apoptotic factors, which ultimately promote recovery of damaged gastric tissue. Therefore, PDRN may serve as a new therapeutic option in the initial treatment of NSAIDs-induced gastropathy.

Design and preparation of polypropylene ultrafiltration membrane with ultrahigh flux for both water and oil

Hydrophilic and/or lipophilic monomers have been successfully grafted into the micropores of PP UF membrane and three kinds of PP UF membranes with ultrahigh flux have been prepared by using microwave heating, a selective heating method. PP UF membrane with ultrahigh flux for water has been prepared by grafting sodium maleate into the micropores of PP UF membrane. The water flux of flat membrane increased from 0 to 1028 g cm−2 h−1 and the flux of hollow fiber membrane increased 12 times compared with unmodified membrane. PP UF membrane with ultrahigh flux for oil has been prepared by grafting Vi-PDMS into the micropores of PP UF membrane with NaCl as microwave absorber. The flux of flat membrane for different oils are increased significantly compared with unmodified membrane. In addition to be used as UF membrane for oil treatment, it can be also used in separation of oil and water because only oil can pass through the membrane and water cannot. PP UF membrane with ultrahigh flux for both water and oils has been also prepared by grafting both sodium maleate and Vi-PDMS into the micropores of PP UF membrane. The prepared UF membranes were characterized and the mechanism for membrane performance enhancement was discussed as well.

Facile preparation of Janus polymer film and application in alleviating water crisis

Water scarcity has been becoming a global water crisis, which has threatened the sustainable development of world economic. In this contribution, it will be reported that Janus polymer film can help us coping with this water crisis through water collection and water evaporation suppressing. A sodium maleate grafted polypropylene (PP-g-NaMA) film was fabricated by solvent induced self-assembly, which has one side hydrophobic and the other side superhydrophilic. In addition to low cost, high performance and excellent stability, the newly developed Janus film can be used for water evaporation reduction and water collection, both with very high efficiency. The durable film can also be recycled easily after using. It is unquestionable that the new finding reported in this paper provides a new avenue to alleviate the water crisis in the world.

Maleic acid modified cellulose for scavenging lead from water.

Macro, micro and nano fibrillary cellulose with sodium maleate groups was synthesized by the reaction of cellulose with maleic anhydride followed by sodium exchange of protons. In the present work, we demonstrate that these carboxylic groups act as chemisorbants towards toxic heavy metal ions present in contaminated water. The effects of the operating parameters such as resident time, temperature, pH, ion concentration and ion nature on chemisorbability were estimated for a given cellulose carboxylate. The kinetic results for the chemisorption of Pb2+ ion were indicative of an intra particle diffusion model and pseudo second order reaction. The chemisorption is well explained by a Freundlich isotherm model showing a multilayer chemisorption, heterogeneous surface and interaction between chemisorbed molecules. The chemisorption capability was enhanced upon decreasing the dimension of the cellulose fibril. The efficiency depended also on the nature of metal ions, dictated by the stability of the geometry of the resultant complex. The maximum chemisorption capacities of macro, micro and nano forms of sodium cellulose-maleate for Pb2+ were 20 mg/g, 40 mg/g and 115 mg/g, respectively at pH of 5.5. The ion exchanged nano-cellulose maleate could be regenerated by sodium chloride solution without loss of efficiency even after 7 cycles.

Effect of the Composition of the Medium on the Selectivity of Deactivation of Skeletal Nickel Catalyst

The effect of the composition of the catalytic system (the nature and composition of the solvent, specifically, aqueous solutions of sodium hydroxide and their mixtures with aliphatic alcohols with the alcohol concentration of 0.11 mole fractions) and additions of a catalyst poison (sodium sulfide) on the catalytic activity of skeletal nickel in the liquid-phase hydrogenation of the carbon‒carbon double bond in sodium maleate was studied. The assumption was made on the decisive role of the solvent in changing the activity of skeletal nickel in the hydrogenation reaction of sodium maleate, which is primarily associated with the redistribution of individual forms of adsorbed hydrogen. In was found that in the water‒sodium hydroxide‒monohydric alcohol solvent skeletal nickel undergoes selective deactivation at the NaOH concentration of 0.01 M, antiselective deactivation at the NaOH concentration of 0.10 M, and variable deactivation at the NaOH concentration of 1.0 M. It is shown that in some cases sodium sulfide additions exert a promoting effect on skeletal nickel in the hydrogenation of sodium maleate.

An organic-skinned secondary coating for carbon-coated LiFePO4 cathode of high electrochemical performances

Carbon coating technologies for olivine-structured LiFePO4 have been successfully commercialized in lithium ion industries. However, up to today, there are still many challenges overcoming the low intrinsic ionic conductivity and surface instability limitations. Herein, we propose a lithium ion conductive organic-skinned secondary coating technique by applying sodium maleate onto the surface of a commercial carbon-coated LiFePO4 cathode. Very distinctive features of the organic skin secondary coating are highly uniform and continuous. More importantly, the abundant carbonyl groups on the LFP surface facilitates facial Li ion transport. The nanostructure tuned organic layer is able to effectively suppress the undesired side reactions at the electrode/electrolyte interface. With 6.0 wt% of the sodium maleate coating, rate capability and long-term cycling behavior of the LiFePO4 cathode at different temperatures are significantly improved. Notably, the well-known impedance rise of LFP cathode with increasing electrochemical cycles is effectively suppressed. An insight into the mechanisms of the secondary sodium maleate coating on the carbon-coated LiFePO4 cathode is discussed.

Atomistic dynamics simulation to solve conformation of model PCE superplasticisers in water and cement pore solution

The working mechanism of polycarboxylate ether (PCE) type superplasticisers in concrete was studied from the point of view of conformational changes of the polymer simulated by molecular dynamics in pure water and cement pore solution. Three typical types of PCEs, namely a methoxy polyethyleneglycol monomethacrylate–sodium methacrylate copolymer (PCEM), a polyethyleneglycol mono allyl ether–sodium maleate copolymer (PCEA) and a polyethyleneglycol mono (3-methyl-3-butenyl) ether–sodium acrylate copolymer (PCEI) were investigated using large-scale atomistic molecular dynamics simulations. It was observed that the PCE polymers which possess negatively charged backbones were stretched in water due to electrostatic repulsion. However, they were found to be significantly shrunken and distorted in synthetic cement pore solution, depending on the polyethylene glycol (PEG) density along the backbone, resulting in the aggregation of PEG side chains due to the salting-out effect.

NICKEL CATALYTIC PROPERTIES IN REACTION OF LIQUID-PHASE HYDROGENATION OF CARBON-CARBON DOUBLE BOND

The hydrogenating of carbon-carbon double bond in a molecule of sodium maleate over a partially deactivated catalysts based on nickel in a water solution at atmospheric pressure was investigated. Kinetic regularities of the investigated processes were obtained. It was found that sulfide additives lead to the decrease in an order of the reaction for both skeletal and supported nickel catalysts, however, the correlation of activity versus the amounts of sulfur introduced is complex and independent on the amount of active metal on the catalyst surface. We proposed the method for the synthesis of a supported nickel catalyst resistant to oxidation with atmospheric oxygen and an activity of the one is more than twice better then activity of Raney nickel. The stability of the nickel catalyst (Raney nickel and nickel supported on silica) in the presence of sulfide ions impurities in the reaction system was shown. It was found that the supported nickel catalyst has a much higher resistance to deactivation than the skeletal catalyst. The role of the support at the adsorption of sulfide from solution during deactivation of the investigated catalysts was demonstrated. It was suggested that the higher stability of the supported catalyst for deactivation is due to the sorption of the catalytic poison by silica gel. It is suggested the possibility of adjusting the selectivity of the catalyst deactivation character without changing the nature of the solvent. It was presented the possibility of purposeful variation in a wide range of adsorption properties of the active metal surface relative to the reactants, which makes possible to develop approaches to the synthesis of catalysts with given parameters of activity and selectivity relative to certain classes of organic compounds.Forcitation:Afineevskii A.V., Prozorov D.A., Osadchaya T.Yu., Sukhachev Ya.P., Lukin M.V. Nickel catalytic properties in reaction of liquid-phase hydrogenation of carbon-carbon double bond. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60.N 6. P. 95-101.

Role of Renal Drug Exposure in Polymyxin B-Induced Nephrotoxicity.

Despite dose-limiting nephrotoxic potentials, polymyxin B has reemerged as the last line of therapy against multidrug-resistant Gram-negative bacterial infections. However, the handling of polymyxin B by the kidneys is still not thoroughly understood. The objectives of this study were to evaluate the impact of renal polymyxin B exposure on nephrotoxicity and to explore the role of megalin in renal drug accumulation. Sprague-Dawley rats (225 to 250 g) were divided into three dosing groups, and polymyxin B was administered (5 mg/kg, 10 mg/kg, and 20 mg/kg) subcutaneously once daily. The onset of nephrotoxicity over 7 days and renal drug concentrations 24 h after the first dose were assessed. The effects of sodium maleate (400 mg/kg intraperitoneally) on megalin homeostasis were evaluated by determining the urinary megalin concentration and electron microscopic study of renal tissue. The serum/renal pharmacokinetics of polymyxin B were assessed in megalin-shedding rats. The onset of nephrotoxicity was correlated with the daily dose of polymyxin B. Renal polymyxin B concentrations were found to be 3.6 ± 0.4 μg/g, 9.9 ± 1.5 μg/g, and 21.7 ± 4.8 μg/g in the 5-mg/kg, 10-mg/kg, and 20-mg/kg dosing groups, respectively. In megalin-shedding rats, the serum pharmacokinetics of polymyxin B remained unchanged, but the renal exposure was attenuated by 40% compared to that of control rats. The onset of polymyxin B-induced nephrotoxicity is correlated with the renal drug exposure. In addition, megalin appears to play a pivotal role in the renal accumulation of polymyxin B, which might contribute to nephrotoxicity.