Sigma-Aldrich Corporation Research Articles

Methodical support for controlling safety of cereals for children (exemplified by furan and methylfuran)

Introduction. The study addresses issues related to developing a procedure for identification of chemicals in food products in practical instrumental investigations. We have validated the method for quantification of a heterocyclic compound (furan) and sylvan (methylfuran) in grain-based cereals for children.
 The aim of this study was to develop a precise GC-MS-method for quantifying a heterocyclic compound and sylvan in food products to control their safety for children, especially infants.
 Materials and methods. The research objects were quantification means (QM) as a certain amount of an analyzed heterocyclic compound and sylvan (the mass share of the analyzed compound is 99%) provided by Sigma Aldrich Corporation (USA), as well as milk and milk-free dry cereals for babies. The study involved using an Agilent 7890А gas chromatographer with 5975С quadrupole mass-spectrometric detector. Sample preparation involved extraction and concentration of furan and methylfuran from food samples by statistical vapour-liquid equilibrium analysis and subsequent gas-chromatographic analysis of vapour phase.
 Results. The procedure for quantification of furan and methylfuran is an original scientific and technical development based on experimental data. It gives an opportunity to identify furan and methylfuran micro-admixtures in food samples with high precision and sensitivity with a range of concentrations between 0.93 and 9.37 ng and between 0.91 and 9.13 ng accordingly. The ultimate indicators describing acceptability of the results obtained by furan and methylfuran quantification included error not higher than 24%, пintra-laboratory precision (σRл ) not higher than 10%, correctness (± σCл ) not higher than 22%.
 Conclusion. The developed technique has shown high selectivity, sensitivity, reliability and satisfactory accuracy. The methodology meets the criteria of the State Standard of the Russian Federation GOST R ISO 5725-1-6-2002 and can be used for laboratory studies of food safety by enterprises and institutions engaged in quality control and research of food products and food raw materials.

Multistage Self-Assembly Strategy: Designed Synthesis of N-doped Mesoporous Carbon with High and Controllable Pyridine N Content for Ultrahigh Surface-Area-Normalized Capacitance

Nitrogen doping could improve the performance of carbon materials in electrocatalysis, CO2 adsorption, and energy storage. [1]However, the control of the doping type and the amount of nitrogen (N)-...

Electrochemical Investigations of L-Tryptophan

IntroductionRecent activity in this laboratory has involved the electrochemistry of amino acids such as L-cysteine and L-histidine in aqueous buffers (1-4). The effect of zinc ions, which are involved in determining the structures of “zinc finger” proteins (5), on the electrochemistry of amino acids has also been investigated. The present work has extended these studies to L-tryptophan and some of its derivatives. ExperimentalMOPS (3-(N-morpholino)propanesulfonic acid) was obtained from Sigma-Aldrich Corporation, and L-tryptophan was obtained from Nutritional Biochemical Systems. Electrochemical experiments were carried out under nitrogen using a Gamry Instruments Interface 1000 potentiostat and Gamry Framework software. Working electrodes were obtained from BASi (Glassy carbon, 3.0 mm diameter; platinum 1.6 mm) and eDAQ (gold, 1.0 mm diameter). Potentials were measured with respect to a silver/silver chloride saturated KCl reference electrode (eDAQ). Results and Discussion Electrochemical studies of L-tryptophan have been carried out in pH 7.4 phosphate buffer, and we have found that L-tryptophan undergoes oxidation more easily than does L-histidine (4). Complexation studies of Zn(II) by L-tryptophan in pH 7.4 MOPS buffer have shown that the extent of complexation is generally similar to that of L-histidine (4). Similar experiments were also carried out on 5-fluoro-tryptophan and 6-fluoro-tryptophan, revealing that they underwent oxidation at somewhat more positive potentials than does L-tryptophan. This observation reflects the electron-withdrawing effect of the fluorine atom. Despite this positive potential shift, the fluorinated tryptophans were found to effectively complex zinc(II) in pH 7.4 MOPS buffer. Finally, initial experiments in the voltammetric behavior of L-tryptophan in the very polar solvent formamide have been initiated.

Electrochemical Studies of Amino Acid: Metal Ion Interactions

Introduction Previous studies (1-3) in this laboratory have involved electrochemical studies of the interaction of Zn(II) ions with L-cysteine in an attempt to more fully characterize the formation of “zinc finger” proteins (4). Subsequent work has involved similar investigations of L-histidine (5), and the work has now been extended to L-tryptophan. Clear evidence for the formation of Zn(II) complexes with L-cysteine and L-histidine has been obtained by cyclic voltammetric peak potential shifts for zinc ion reduction (2, 5). In the present study, we have extended this work to L-tryptophan by means of voltammetric studies of the amino acid and by investigation of its interactions with metals such as zinc and copper. Results for the interaction of bismuth(III) with L-cysteine and with glutathione, prompted by the significance of such interactions in human biochemistry (6-8), are also planned for presentation. Experimental L-Cysteine, L-glutathione, L-histidine, and MOPS (3-(N-morpholino)propanesulfonic acid) were obtained from Sigma-Aldrich Corporation, and L-tryptophan was obtained from Nutritional Biochemicals Corporation. Electrochemical experiments were carried out under nitrogen using a Gamry Instruments Interface 1000 potentiostat and Gamry Framework software. Working electrodes were obtained from BASi (Glassy carbon, 3.0 mm diameter; platinum 1.6 mm) and eDAQ (gold, 1.0 mm diameter). Potentials were measured with respect to a silver/silver chloride saturated KCl reference electrode (BASi). Results and Discussion Electrochemical studies of L-tryptophan in pH 7.4 phosphate buffer have shown that this amino acid undergoes oxidation at +0.82 V vs Ag/AgCl at 100 mV/s, which is a considerably less positive potential than that observed for L-histidine (5). The effects of L-tryptophan additions to ZnSO4 added to pH 7.4 MOPS buffer were found to be generally similar to those for L-histidine (5). For the case of interactions of L-cysteine with Bi(III) in pH 7.4 MOPS buffer, Bi(NO3)3 was added to pH 7.4 MOPS buffer resulting in the formation of slightly soluble hydroxyl bismuth complexes. Upon addition of 1:1 bismuth(III):L-cysteine, the solution appearance changed from cloudy to clear, and voltammetric currents increased substantially, indicating a strong interaction between bismuth(III) and L-cysteine. In addition, a negative voltammetric shift for the bismuth(III) reduction potential was observed, as was the case for the zinc(II):L-cysteine interaction (2). Further additions of L-cysteine were found to produce additional negative shifts for bismuth(III) reduction. Similar behavior for L-glutathione was observed. MALDI-TOF spectra for the 1:2 Bi(III):L-glutathione and similar complexes in aqueous solutions have been reported (10) and provide supporting evidence for the electrochemical results in the present study. A similar spectrum for the 1:2 Bi(III):L-glutathione complex in pH 7.4 MOPS buffer has been obtained in the present work.

Separation of Copper from Electric Cable Waste Based on Mineral Processing Methods: A Case Study

Recycling of electrical cable waste requires a separation between the metal and the insulating material. The objective of this work was to separate the copper from the plastic in electrical cable waste previously ground below 2 mm, using jigging, shaking table and froth flotation techniques. The effect of particle size was also analysed. Jigging and shaking table proved to be effective in the separation of copper from plastics. The result was a copper concentrate with a copper grade of about 97% by both methods and a copper recovery of about 97%. Jigging separation had similar separation efficiencies in the seven-sized fractions, but in shaking table, the separation efficiency improved with an increase in particles size. The separation achieved by froth flotation had lower efficiencies (85%), because plastics are naturally hydrophobic and copper presents some hydrophobic behaviour. In this technique, the addition of depressant agents was mandatory for the depression of copper, even at low concentrations. The best results were obtained with concentrations of 10−1 mg/L of sodium sulfide (407410 Sigma-Aldrich, Sigma-Aldrich Corporation, St. Louis, MO, USA) and meso-2,3-Dimercaptosuccinic acid (D7881 Sigma-Aldrich).

Electrochemical Studies of Bismuth/L-Cysteine and Bismuth/L-Glutathione Interactions in Aqueous Buffers

Introduction Previous studies (1-3) in this laboratory have involved electrochemical studies of the interaction of Zn(II) ions with L-cysteine in an attempt to more fully characterize the formation of “zinc finger” proteins (4). This interaction can be investigated both by the effect of Zn(II) addition upon the oxidation of the thiol group of L-cysteine, and by the effect of L-cysteine addition upon the reduction potential of Zn(II). In particular, the addition of L-cysteine to ZnSO4 dissolved in pH 7.4 MOPS buffer results in a large negative shift in the reduction potential for Zn(II) ions (2). This behavior is clear evidence for the formation of a Zn2+ : Cysteine complex. In the present study, we have extended this work to the interaction of bismuth(III) with L-cysteine and with glutathione, prompted by the significance of such interactions in human biochemistry (5-7). Experimental L-Cysteine, L-glutathione, and MOPS (3-(N-morpholino)propanesulfonic acid) were obtained from Sigma-Aldrich Corporation, and bismuth(III) nitrate was obtained from Baker. Electrochemical experiments were carried out under nitrogen using a Gamry Instruments Interface 1000 potentiostat and Gamry Framework software. Working electrodes were obtained from BASi (Glassy carbon, 3.0 mm diameter; platinum 1.6 mm) and eDAQ (gold, 1.0 mm diameter). Potentials were measured with respect to a silver/silver chloride saturated KCl reference electrode (BASi). Results and Discussion It has been found that Bi(NO3)3 is only slightly soluble in pH 7.4 MOPS buffer due to probable formation of hydroxyl complexes (8). It is, however, possible to observe small currents for deposition and subsequent stripping of bismuth at gold and glassy carbon in this solution. Upon addition of 1:1 bismuth(III):L-cysteine, the solution appearance changed from cloudy to clear, and voltammetric currents increased substantially, indicating a strong interaction between bismuth(III) and L-cysteine. In addition, a negative voltammetric shift for the bismuth reduction potential was observed, as was the case for the zinc(II):L-cysteine interaction (2). Further additions of L-cysteine were found to produce additional negative shifts for bismuth(III) reduction. Similar behavior for L-glutathione was observed. MALDI-TOF spectra for the 1:2 Bi(III):L-glutathione and similar complexes in aqueous solutions have been reported (9) and provide supporting evidence for the electrochemical results in the present study. A similar spectrum for the 1:2 Bi(III):L-glutathione complex in pH 7.4 MOPS buffer has been obtained in the present work. References G. T. Cheek and M. A. Worosz, ECS Transactions, 2016, 72(27), 1-8.M. Y. Doan, M. A. Worosz, and G.T. Cheek, ECS Transactions, 2017, 77(11), 1537-1544.G. T. Cheek, M. A. Worosz, M. Y. Doan, and D. C. Clark, ECS Transactions 2017, 80 ( 10 ), 1159-1166. C.K. Mathews, K.E. Van Holde, D.R. Appling, and S. J. Anthony-Cahill, Biochemistry, 4th Edition, Pearson Canada, Toronto, 2013.G. G. Briand and N. Burford, Chem. Rev., 1999, 99, 2601-2657.R. Ge and H. Sun, Acc. Chem. Res., 2007, 40, 267-274.Y. Hong, Y.-T Lai, G. C-F Chan, and H. Sun, PNAS, 2015, 112(11), 3211–3216. J. Kragten, L. G. Decnop-Weever, and P. Gründler, Talanta, 1993, 40(4), 485-490.N. Burford, M. D. Eelman, D. E. Mahony, and M. Morash, Chem. Commun., 2003, 146–147.

Electrochemical Studies of L-Histidine

Introduction The naturally occurring amino acid L-histidine is involved in many important biochemical processes, particularly those involving complexation of metal ions by histidine. Such interactions are involved in the formation of “zinc finger” proteins (1) and in proteins containing copper(II) ions (2). The imidazole moiety in L-histidine is electrochemically active, although at rather highly positive potentials (3), and this behavior allows investigation of its properties and interactions with other substances. The research involved in this paper deals with the electrochemical investigation of L-histidine in buffered aqueous media by techniques such as cyclic and square-wave voltammetry. Further studies of the complexation of L-histidine with zinc(II) ions is also planned for presentation. These studies complement those carried out previously with L-cysteine in this laboratory (4, 5). Experimental L-Histidine and ZnSO4 . 7 H2O were obtained from Sigma-Aldrich Corporation. Electrochemical experiments were carried out under nitrogen using a Gamry Instruments Interface 1000 potentiostat and Framework software. Working electrodes were obtained from BASi (Glassy carbon, 3.0 mm diameter; platinum 1.6 mm) and eDAQ (gold, 1.0 mm diameter). Potentials were measured with respect to a silver/silver chloride saturated KCl reference electrode (BASi). Results and Discussion The electroactive nature of the imidazole portion of L-histidine is illustrated in Figure 1, which presents the square-wave voltammogram (SWV) of 8 mM L-histidine in pH 7.4 phosphate buffer. Two partially resolved oxidation processes are evident, and the resolution was poorer using cyclic voltammetry. It was found that the SWV peak currents were nonlinear with L-histidine concentration. Addition of ZnSO4 to L-histidine (1:2 molar ratio) produced a positive 50 mV potential shift for the SWV L-histidine oxidation, consistent with complexation of Zn2+ with L-histidine. Similar results were observed for L-cysteine (5). Further work with Zn2+ complexation by L-histidine was then carried out in pH 7.4 MOPS buffer at glassy carbon. Initial addition of ZnSO4 produced a symmetrical SWV Zn2+ reduction peak upon scanning to more negative potentials, and addition of L-histidine caused a -100 mV potential shift in the reduction peak at the 1:2 ZnSO4 : L-histidine point. The shape of the square-wave voltammetric reduction peak was also found to become somewhat narrower upon addition of L-histidine. Investigations of L-histidine under other conditions (pH 11) and using other techniques (electrochemical impedance spectroscopy) are also intended for inclusion in this presentation. References C.K. Mathews, K.E. Van Holde, D.R. Appling, and S. J. Anthony-Cahill, Biochemistry, 4th Edition, Pearson Canada, Toronto, 2013.T. Venelinov, S. Arpadjan, I. Karadjova, and J. Beattie, Acta Pharm., 2006, 56, 105-112. L-C. Chen, C-C. Chang, and H-C. Chang, Electrochem. Acta, 2008, 53, 2883-2889.G. T. Cheek and M. A. Worosz, ECS Transactions, 2016, 72(27), 1-8.M. Y. Doan, M. A. Worosz, and G.T. Cheek, ECS Transactions, 2017, 77(11), 1537-1544. Figure 1. Square-wave voltammograms at glassy carbon in aqueous pH 7.4 phosphate buffer, ESW = 25 mV, ΔE = 2 mV, frequency = 10 Hz. Solid black line : L-Histidine 8 mMDashed red line : pH 7.4 background Figure 1

(Invited) Electrochemical Studies of Zinc/Cysteine Interactions in Aqueous Buffers

Introduction The naturally occurring amino acid L-cysteine is involved in many important biochemical processes, including the formation of “zinc finger” proteins (1). The electroactive thiol group in cysteine allows electrochemical investigation of its properties and interactions with other substances. The present contribution deals with the complexation of L-cysteine with zinc(II) ions in various buffered aqueous media and is a continuation of work previously presented (2). Experimental L-Cysteine was obtained from Sigma-Aldrich Corporation. Electrochemical experiments were carried out under nitrogen using a Gamry Instruments Interface 1000 potentiostat and Framework software. Working electrodes were obtained from BASi (Glassy carbon, 3.0 mm diameter; platinum 1.6 mm) and eDAQ (gold, 1.0 mm diameter). Potentials were measured with respect to a silver/silver chloride saturated KCl reference electrode (BASi). Results and Discussion Recent work from this laboratory has shown that the interaction of zinc(II) ions, added as ZnSO4 heptahydrate, with L-cysteine can be followed by cyclic voltammetry (Figure 1). This work is intended as a model for the formation of “zinc finger” proteins, which involve interactions between zinc(II) and cysteine and histidine units in the protein structure (1). Figure 1 (a) shows the voltammogram for 8.6 mM L-cysteine in 0.1 M pH 7.4 phosphate buffer at glassy carbon. Upon addition of ZnSO4 to L-cysteine in a 1:2 Zn2+: Cysteine mole ratio [Figure 1(b)], the broad oxidation process underwent a significant shift to a more positive potential. This observation is consistent with the complexation of Zn(II) by L-cysteine. Upon sweeping to more negative potentials, reduction of the complex was found to occur near the solvent reduction limit, followed by zinc stripping at approximately -1.0 V vs Ag/AgCl. Interesting comparisons with results at gold electrodes (2) can also be made. Further details for the complexation process are also planned for presentation. Other investigations have involved electrochemical impedance spectroscopy (EIS) to determine the extent to which L-cysteine interacts with various electrode surfaces. References C.K. Mathews, K.E. Van Holde, D.R. Appling, and S. J. Anthony-Cahill, Biochemistry, 4th Edition, Pearson Canada, Toronto, 2013. G. T. Cheek and M. A. Worosz, ECS Transactions, 2016, 72(27), 1-8. Figure 1. Cyclic voltammograms at glassy carbon in aqueous pH 7.4 phosphate buffer, 100 mV/s scan rate. Solid black line : L-Cysteine 8.6 mM, initial positive-going sweep Dashed red line : ZnSO4 . 7 H2O 4.3 mM addition, to previous solution, initial positive-going sweep Figure 1

Electrochemical Behavior of Toluene in Adiponitrile

Introduction Previous studies from this laboratory have involved the characterization of adiponitrile (NCCH2CH2CH2CH2CN) / tetraethylammonium tetrafluoroborate (TEABF4) as a versatile solvent system for organic electrochemistry (1,2). One very valuable feature of this system is the wide potential limit range, as noted by others (3). Considering that the positive potential limit is +5 V vs Ag/AgCl, the system is particularly attractive for the study of hydrocarbon oxidation. The present paper is a continuation of the study of various hydrocarbons in adiponitrile (4). Experimental Adiponitrile was obtained from Sigma-Aldrich Corporation, and tetraethylammonium tetrafluoroborate (TEA BF4) was purchased from Southwestern Analytical Chemicals. Cyclic voltammograms were obtained on a PAR 283 potentiostat using PowerSuite software. Potentials are referenced against a Ag/AgCl reference electrode (1). Platinum and glassy carbon electrodes (1 mm diameter each) were obtained from eDAQ. Results and Discussion Cyclic voltammograms of 6.8 mM toluene in adiponitrile / 0.2 M TEABF4 are shown in the attached figure. An initial positive scan at platinum from 0.00 V produced a multicomponent, irreversible oxidation process between +2V and +3V vs Ag/AgCl, with considerable current on the second sweep (not shown). Results at glassy carbon were somewhat similar; however, there is little evidence of multiple oxidation processes. In addition, the lack of oxidation current on the second sweep at glassy carbon indicates that considerable electrode filming at glassy carbon is involved. Reported peak potentials in acetonitrile / NaClO4 are similar to the values observed in the present study (5). This study shows that adiponitrile / 0.2 M TEA BF4 is a useful solvent system for the electrochemical study of toluene. References G.T. Cheek, ECS Trans., 58(46), 45-51 (2014). G.T. Cheek, ECS Trans., 61(30), 19-24 (2104). H. Duncan, N. Salem, and Y. Abu-Lebdeh, J. Electrochem. Soc., 160(6) A838-A848 (2013). G.T. Cheek, ECS Trans., 72(26), 1-5 (2016). W.C. Neikam and M.M. Desmond, J. Am. Chem. Soc., 86, 4811-4814 (1964). Figure 1. Cyclic voltammograms of 6.8 mM toluene in adiponitrile / 0.2 M TEA BF4 at 100 mV/s. Black (solid) curve : Platinum ; Red (dotted) curve : Glassy carbon Figure 1

Endogeous sulfur dioxide protects against oleic acid-induced acute lung injury in association with inhibition of oxidative stress in rats

The role of endogenous sulfur dioxide (SO2), an efficient gasotransmitter maintaining homeostasis, in the development of acute lung injury (ALI) remains unidentified. We aimed to investigate the role of endogenous SO2 in the pathogenesis of ALI. An oleic acid (OA)-induced ALI rat model was established. Endogenous SO2 levels, lung injury, oxidative stress markers and apoptosis were examined. OA-induced ALI rats showed a markedly downregulated endogenous SO2/aspartate aminotransferase 1 (AAT1)/AAT2 pathway and severe lung injury. Chemical colorimetry assays demonstrated upregulated reactive oxygen species generation and downregulated antioxidant capacity in OA-induced ALI rats. However, SO2 increased endogenous SO2 levels, protected against oxidative stress and alleviated ALI. Moreover, compared with OA-treated cells, in human alveolar epithelial cells SO2 downregulated O2− and OH− generation. In contrast, L-aspartic acid-β-hydroxamate (HDX, Sigma-Aldrich Corporation), an inhibitor of endogenous SO2 generating enzyme, promoted free radical generation, upregulated poly (ADP-ribose) polymerase expression, activated caspase-3, as well as promoted cell apoptosis. Importantly, apoptosis could be inhibited by the free radical scavengers glutathione (GSH) and N-acetyl-L-cysteine (NAC). The results suggest that SO2/AAT1/AAT2 pathway might protect against the development of OA-induced ALI by inhibiting oxidative stress.

Er:YAG Laser Activation of Sodium Hypochlorite for Root Canal Soft Tissue Dissolution

The aim of this in vitro study was to investigate the effect of Er:YAG laser irradiation on the ability of sodium hypochlorite (NaOCl) to dissolve soft tissue during endodontic procedures. Two acrylic glass plates, each containing a semi-canal, were bolted together to form a complete canal. This geometry permitted one semi-canal to be filled with fine liver sausage of bovine origin dyed by methylene blue and the other with NaOCl (4.00-4.99% available chlorine; Sigma-Aldrich Corporation, St. Louis, MA), which was then activated by Er:YAG laser irradiation (KEY Laser 3; KaVo, Biberach, Germany) using a plain-ended fiber tip and a range of output energy and repetition rate. To achieve relatively low output energy from high input energy, the laser beam was attenuated by placing glass slides in the beam path. The resultant images acquired were analyzed using pixel-based analysis. Samples were statistically analyzed (two-way ANOVA, P < 0.05, univariate, bifactorial; IBM SPSS Statistics 19, SPSS Inc., Chicago, IL). Both output energy and repetition rate significantly influenced the tissue dissolution ability of NaOCl (P < 0.05). Within the limitations of this in vitro study, we conclude that laser activation of NaOCl at 200 mW output power leads to effective soft tissue dissolution. This finding can be of use to endodontists pursuing effective soft tissue dissolution from their irrigants.

Scriptaid, a novel histone deacetylase inhibitor, protects against traumatic brain injury via modulation of PTEN and AKT pathway : scriptaid protects against TBI via AKT.

Traumatic brain injury (TBI) is a leading cause of motor and cognitive deficits in young adults for which there is no effective therapy. The present study characterizes the protective effect of a new histone deacetylase inhibitor, Scriptaid (Sigma-Aldrich Corporation, St. Louis, MO), against injury from controlled cortical impact (CCI). Scriptaid elicited a dose-dependent decrease in lesion size at 1.5 to 5.5mg/kg and a concomitant attenuation in motor and cognitive deficits when delivered 30minutes postinjury in a model of moderate TBI. Comparable protection was achieved even when treatment was delayed to 12h postinjury. Furthermore, the protection of motor and cognitive functions was long lasting, as similar improvements were detected 35days postinjury. The efficacy of Scriptaid (Sigma-Aldrich Corporation) was manifested as an increase in surviving neurons, as well as the number/length of their processes within the CA3 region of the hippocampus and the pericontusional cortex. Consistent with other histone deacetylase inhibitors, Scriptaid treatment prevented the decrease in phospho-AKT (p-AKT) and phosphorylated phosphatase and tensin homolog deleted on chromosome 10 (p-PTEN) induced by TBI in cortical and CA3 hippocampal neurons. Notably, the p-AKT inhibitor LY294002 attenuated the impact of Scriptaid, providing mechanistic evidence that Scriptaid functions partly by modulating the prosurvival AKT signaling pathway. As Scriptaid offers long-lasting neuronal and behavioral protection, even when delivered 12h after controlled cortical impact, it is an excellent new candidate for the effective clinical treatment of TBI.

Migration of Acrylic Monomers from Methacrylate Polymers - Establishing Parameters for Migration Modelling

Acrylic acid-based and methacrylic acid-based monomers are widely used for the manufacture of polymers, for polymer dispersions or for other specialty resins. Some of these applications cause interactions between the polymer and contact medium such as food contact materials, eyeglasses, contact lenses or toys. More specifically, migration of monomers from the polymer into the contact medium may occur, which needs to be evaluated for safety purposes. The objective of this study was to investigate the basic diffusion properties of acrylic polymers with respect to representative monomers in order to establish a scientific basis for migration modelling simulating the mass transport of monomers from the polymers when they are in contact with foods, human skin or body fluids such as sweat and saliva. For this purpose, 11 representative acrylic polymers containing five different acrylic monomers (MA, EA, BA, MMA and nBMA) were studied in extensive kinetic migrations experiments in contact with five different contact media (simulants) at three different temperatures (20°C, 40°C and 60°C). The simulants were selected according to the applications: toys were simulated by saliva simulant and articles coming in contact with human skin by sweat simulant. For food contact applications, water (aqueous foods), Miglyol 840 (Sasol, Witten, Germany) (fatty food) and Tenax® (Sigma-Aldrich Corporation, Munich, Germany) (an adsorbent simulating dry foods) were selected. The diffusion coefficients (D) of the monomers in the polymer as well as partition coefficients between polymer and contact media were derived. It was found that those acrylic polymer materials used for rigid plastics applications exhibit extremely low diffusion behaviour, whereas acrylic polymer resins used for coating applications showed somewhat higher diffusion behaviour but this still at very low rates in comparison with other typical polymers used for the manufacture of food packaging materials. As a result, conservative polymer-specific constants in support of migration modelling were established, and the specifications for the model general applicability were determined and specified. The parameter related to the polymers' intrinsic mobility is applicable to model migration of any other organic chemical substances, which may be present in acrylic polymers as potential migrants when they have comparable or higher molecular weights than the studied monomers. Copyright © 2012 John Wiley & Sons, Ltd.

Preparation, characterization, and cytotoxicity of CPT/Fe2O3-embedded PLGA ultrafine composite fibers: a synergistic approach to develop promising anticancer material

The aim of this study was to fabricate camptothecin/iron(III) oxide (CPT/Fe₂O₃)-loaded poly(D,L-lactide-co-glycolide) (PLGA) composite mats to modulate the CPT release and to improve the structural integrity and antitumor activity of the released drug. The CPT/Fe₂O₃-loaded PLGA ultrafine fibers were prepared for the first time by electrospinning a composite solution of CPT/Fe₂O₃ and neat PLGA (4 weight percent). The physicochemical characterization of the electrospun composite mat was carried out by scanning electron microscopy, energy dispersive X-ray spectroscopy, electron probe microanalysis, thermogravimetry, transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray diffraction pattern. The medicated composite fibers were evaluated for their cytotoxicity on C2C12 cells using Cell Counting Kit-8 assay (Sigma-Aldrich Corporation, St Louis, MO). The in vitro studies indicated a slow and prolonged release over a period of 96 hours with mild initial burst. Scanning electron microscopy, thermogravimetry, and X-ray diffraction studies confirmed the interaction of CPT/Fe₂O₃ with the PLGA matrix and showed that the crystallinity of CPT decreased after loading. Incorporation of CPT in the polymer media affected both the morphology and the size of the CPT/Fe₂O₃-loaded PLGA composite fibers. Electron probe microanalysis and energy dispersive X-ray spectroscopy results confirmed well-oriented composite ultrafine fibers with good incorporation of CPT/Fe₂O₃. The cytotoxicity results illustrate that the pristine PLGA did not exhibit noteworthy cytotoxicity; conversely, the CPT/Fe₂O₃ composite fibers inhibited C2C12 cells significantly. Thus, the current work demonstrates that the CPT/Fe₂O₃-loaded PLGA composite fibers represent a promising chemotherapeutic system for enhancing anticancer drug efficacy and selectively targeting cancer cells in order to treat diverse cancers.

Antileukaemia effect of rapamycin alone or in combination with daunorubicin on ph+ acute lymphoblastic leukaemia cell line

The translocation (9;22) (q34;q11), known as the Philadelphia (Ph) chromosome and bcr-abl fusion gene, is the common cytogenetic abnormality and an unfavourable prognosis in adult acute lymphoblastic leukaemia (ALL). Although chemotherapeutic treatment produced high rates of complete response in approximately 70%-80% of newly diagnosed Ph+ ALL, the onset of resistance and clinical relapse is rapid. Therefore, the efficacy of treatment in Ph+ ALL is still to be determined. In this study, we aimed to assess the antileukemic activity of rapamycin (RAPA) (Sigma-Aldrich Corporation, MO, USA), a mammalian target of rapamycin inhibitor, alone and in combination with daunorubicin (DNR) (Pharmacia & Upjohn Company, Germany) in a Ph+ acute lymphoblastic cell line SUP-B15 and a primary Ph+ ALL sample in vitro. Here, we demonstrated that 50 nmol/L of RAPA significantly intensified the inhibition induced by DNR on both Ph+ ALL cell line and a primary Ph+ ALL sample. Notably, we reported that the consequence of DNR treatment induced the over expression of the components of mammalian target of rapamycin signalling pathway, whereas RAPA effectively eliminated this deleterious side effect of DNR, which might enhance DNR's ability to kill drug-resistant cancer. The synergistic effect was also associated with the increase in autophagy, blockage of cell cycle progression in the G1 phase. Altogether, our results suggest that DNR in combination with RAPA is more effective in the treatment of Ph+ ALL compared with DNR alone.

Letter to the Glyco-Forum: Effective glycoanalysis with Maackia amurensis lectins requires a clear understanding of their binding specificities

Letter to the Glyco-Forum: Effective glycoanalysis with Maackia amurensis lectins requires a clear understanding of their binding specificities

249 PROFILE OF MEMBERS OF IGF SYSTEM GENE EXPRESSION IN BOVINE IMMATURE OOCYTES: COMPARISON BETWEEN NELLORE (BOS INDICUS) AND HOLSTEIN (BOS TAURUS)

There is evidence that IGF system can be involved in the oocyte competence and, consequently, in the embryo development. To better understand possible differences between Bos taurus and Bos indicus in in vitro embryo development, the current work aimed to assess the expression of IGF ligands (IGF-1 and 2), types 1 and 2 IGF receptors (IGFR1 and 2), IGF-binding proteins 2 and 4 (IGFBP-2 and 4), and type A pregnancy-associated plasmatic protein (PAPP-A) mRNA in bovine immature oocytes fromBos Taurus and Bos indicus. Nellore and Holstein cows were submitted to ovum pickup, and the oocytes with grade 1, 2, and 3 were selected. To remove cumulus cells and pellucida zone, respectively, the oocytes were submitted to vortex (900 × g for 3 min) and protease treatment (Protease® from Streptomyces griseus, Sigma-Aldrich Corporation, St. Louis, MO, USA). Pools of 20 oocytes obtained from Nellore (n = 8) and Holstein (n = 4) cows were submitted to total RNA extraction (RNeasy, Qiagen, Valencia, CA, USA). The gene expression of target genes was measured by real-time RT-PCR with oligo-dT in the RT and bovine-specific primers in the PCR. Expression of cyclophlin A (CYC-A) was used as internal control. The means of mRNA levels of target genes between the breeds were compared using t-test and Mann-Whitney test when the data had normal or not normal distribution, respectively. The means values of mRNA expression of IGF-1, IGF-2, IGF receptors (1 and 2), and IGFBP 2 and 4 were greater in Holstein (0.96 ± 0.21, 0.74 ± 0.27, 1.08 ± 0.04, 1.19 ± 0.5, 1.21 ± 0.23, 0.53 ± 0.15, respectively) compared with Nellore (0.48 ± 0.10, 0.07 ± 0.02, 0.04 ± 0.03, 0.06 ± 0.02, 0.05 ± 0.01, 0.03 ± 0.15, respectively; P &lt; 0.01). Never- theless, mRNA expression of PAPP-A was much greater in Nellore (28.10 ± 18.96) than in Holstein (1.32 ± 0.17; P &lt; 0.05). These results suggest that high expression of PAPP-A and low expression of IGFBP-2 and 4 could allow more efficiency on the degradation of IGFBP and increase the IGF bioavailability in the oocytes from Nellore as compared with Holstein cows. Satrapa, Simões, and Castilho received a fellowship and funding from FAPESP (São Paulo, Brazil).

The calcimimetic AMG 641 abrogates parathyroid hyperplasia, bone and vascular calcification abnormalities in uremic rats

Calcimimetics and vitamin D sterols reduce serum parathyroid hormone (PTH) in patients with secondary hyperparathyroidism receiving dialysis, a disease state associated with parathyroid hyperplasia, vascular calcification, bone disease, and increased mortality. The aim of this study was to determine the effects of the research calcimimetic AMG 641 (Amgen, Inc., Thousand Oaks, CA) or calcitriol (Sigma Aldrich Corporation, St. Louis, MO) on vascular calcification in a rodent model of progressive uremia with accompanying secondary hyperparathyroidism induced by dietary adenine. Treatment effects on parathyroid gland hyperplasia and bone loss were also investigated. Rats were treated daily with vehicle, calcitriol (10 ng), AMG 641 (3 mg/kg), or no treatment during the 4 week period the animals were fed adenine. The uremia-induced increases in serum PTH levels were significantly attenuated by both AMG 641 (> 90%) and calcitriol (~ 50%). AMG 641 significantly reduced calcium–phosphorus product (Ca × P) and significantly attenuated the development of both parathyroid hyperplasia and vascular calcification. In addition, AMG 641 prevented the defects in trabecular bone volume, trabecular number, and bone mineralization, as well as increases in trabecular spacing in this rodent model of secondary hyperparathyroidism. Calcitriol (10 ng/rat) decreased osteoid surface/bone surface, but had no effects on other bone parameters, or parathyroid hyperplasia (likely due to the lower PTH suppressive effect of calcitriol at the dose used in this study). However, this dose of calcitriol significantly exacerbated vascular calcification. These results suggest that calcimimetics can reduce the development of vascular calcification, parathyroid hyperplasia and bone abnormalities associated with secondary hyperparathyroidism.

294 THE EFFECT OF PLASMIN ON THE IN VITRO FERTILIZATION ABILITY OF PORCINE GAMETES

Plasminogen activators (PAs) are specific proteolytic enzymes that convert the inactive proenzyme plasminogen to plasmin. The plasmin formed is a nonspecific, potent protease that cleaves blood fibrin clots and several other extracellular proteins. The purposes of the present study were (1) to assess the effect of plamin on sperm viability and acrosome reaction (AR), (2) to examine the effect of plasmin on zona pellucida (ZP) solubility and the binding of sperm to ZP, and (3) to evaluate the effect of plasmin on fertilization responses, including penetration and incidence of polyspermy during in vitro fertilization in the pig. Ejaculated semen was collected from three mature Duroc boars by artificial vagina. The same three boars were used for all experiments. The oocyte maturation medium used was North Carolina State University-23 (NCSU-23) medium supplemented with 10% (v/v) porcine follicular fluid (pFF), 0.6 mM cysteine, 10 IU/mL human chorionic gonadotropin (hCG; Sigma-Aldrich Corporation, St. Louis, MO, USA), and 10 IU/mL pregnant mare's serum gonadotropin (PMSG; Sigma). Porcine spermatozoa, which were washed in Dulbecco PBS (Sigma), were resuspended and incubated in fertilization medium (mTBM) containing 0, 0.1, 1.0, 10.0, or 100.0 ng/mL plasmin (Sigma). Data were analyzed by ANOVA and Duncan's multiple-range test using the Statistical Analysis System (SAS Institute, Inc., Cary, NC, USA). The present study suggests that sperm viability was not affected by plasmin treatment. Also, addition of plasmin in doses ranging between 0.1 and 100.0 ng/mL for 2, 4, or 6 h to washed boar spermatozoa resulted in enhancement of acrosome reaction (AR), compared with untreated cells. Concentrations of 0 and 0.1 ng/mL plasmin (83 � 15 and 95 � 18 sperm/oocyte, respectively) had no effect on sperm binding, whereas 1.0 (123 � 21 sperm/oocyte), 10.0 (124 � 16 sperm/oocyte), and 100 ng/mL (124 � 15 sperm/oocyte) plasmin increased (P &lt; 0.05) sperm binding, compared with the control. The zona pellucida solubility (zona digestion time) was significantly (P &lt; 0.05) lower in medium with 1.0 (123 � 24 s), 10.0 (99 � 15 s), or 100.0 ng/mL (95 � 19 s) plasmin, compared with control (176 � 27 s). When porcine oocytes and spermatozoa were co-incubated in various concentrations of plasmin for 6 h, the penetration rate was significantly (P &lt; 0.05) higher in medium with 1.0 ng/mL plasmin (77.5 � 3.1%), compared with control. However, there were no significant differences in the polyspermic rates and mean numbers of sperm (MNS)/oocyte among the groups treated with plasmin and the control group. We found that addition of plasmin to fertilization medium increases the percentage of acrosome-reacted spermatozoa and the sperm-binding ability of the pig ZP. These results suggest that plasmin may play a role in events related to fertilization in the pig.

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