Labile Plasma Iron Generation After Intravenous Iron is Time-dependent and Transitory in Patients Undergoing Chronic Hemodialysis

Iron supplementation in hemodialysis patients is fundamental to erythropoiesis, but may cause harmful effects. We measured oxidative stress using labile plasma iron (LPI) after parenteral iron replacement in chronic hemodialysis patients. Intravenous iron saccharate (100 mg) was administered in patients undergoing chronic hemodialysis (N = 20). LPI was measured by an oxidant-sensitive fluorescent probe at the beginning of dialysis session (T0), at 10 min (T1), 20 min (T2), and 30 min (T3) after the infusion of iron and at the subsequent session; P < 0.05 was significant. The LPI values were significantly raised according to the time of administration and were transitory: -0.02 +/- 0.20 mu mol/L at the beginning of the first session, 0.01 +/- 0.26 mu mol/L at T0, 0.03 +/- 0.23 mu mol/L at T1, 0.09 +/- 0.28 mmol/L at T2, 0.18 +/- 0.52 mmol/L at T3, and -0.02 +/- 0.16 mmol/L (P = 0.001 to 0.041) at the beginning of the second session. The LPI level in patients without iron supplementation was -0.06 +/- 0.16 mmol/L. Correlations of LPI according to time were T1, T2, and T3 vs. serum iron (P = 0.01, P = 0.007, and P = 0.0025, respectively), and T2 and T3 vs. transferrin saturation (P = 0.001 and P = 0.0003, respectively). LPI generation after intravenous saccharate administration is time-dependent and transitorily detected during hemodialysis. The LPI increment had a positive correlation to iron and transferrin saturation.

Total Trans Fatty Acid Analysis in Spreadable Cheese by Capillary Zone Electrophoresis

An alternative method for determination of total trans fatty acids expressed as elaidic acid by capillary zone electrophoresis (CZE) under indirect UV detection at 224 nm within an analysis time of 7.5 min was developed. The optimized running electrolyte includes 15.0 mmol L(-1) KH(2)PO(4)/Na(2)HPO(4) buffer (pH similar to 7.0), 4.0 mmol L(-1) SDBS, 8.0 mmol L(-1) Brij35, 45%v/v ACN, 8% methanol, and 1.5% v/v n-octanol. Baseline separation of the critical pair C18-9cis/C18:1-9t: with a resolution higher than 1.5 was achieved using C15:0 as the internal standard. The optimum capillary electrophoresis (CE) conditions for the background electrolyte were established with the aid of Raman spectroscopy and experiments of a 3(2) factorial design. After response factor (R(F)) calculations, the CE method was applied to total trans fatty acid (TTFA) analysis in a hydrogenated vegetable fat (HVF) sample, and compared with the American Oil Chemists` Society (AOCS) official method by gas chromatography (GC). The methods were compared with an independent sample t test, and no significant difference was found between CE and GC methods within the 95% confidence interval for six genuine replicates of TTFA analysis (p-value > 0.05). The CE method was applied to TTFA analysis in a spreadable cheese sample. Satisfactory results were obtained, indicating that the optimized methodology can be used for trans fatty acid determination for these samples.

Host-guest system of 4-nerolidylcatechol in 2-hydroxypropyl-beta-cyclodextrin: preparation, characterization and molecular modeling

The interaction of 4-nerolidylcatechol (4-NRC), a potent antioxidant agent, and 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was investigated by the solubility method using Fourier transform infrared (FTIR) methods in addition to UV-Vis, (1)H-nuclear magnetic resonance (NMR) spectroscopy and molecular modeling. The inclusion complexes were prepared using grinding, kneading and freeze-drying methods. According to phase solubility studies in water a B(S)-type diagram was found, displaying a stoichiometry complexation of 2:1 (drug:host) and stability constant of 6494 +/- A 837 M(-1). Stoichiometry was established by the UV spectrophotometer using Job`s plot method and, also confirmed by molecular modeling. Data from (1)H-NMR, and FTIR, experiments also provided formation evidence of an inclusion complex between 4-NRC and HP-beta-CD. 4-NRC complexation indeed led to higher drug solubility and stability which could probably be useful to improve its biological properties and make it available to oral administration and topical formulations.

Structural parameters of polyacrylamide hydrogels obtained by the Equilibrium Swelling Theory

In this paper, the synthesis and structural characterization of a series of polyacrylamide hydrogels with different degrees of reticulation are reported. Although the Equilibrium Swelling Theory was recognized as a simple and reliable tool for the determination of structural hydrogels network parameters like equilibrium degree of swelling, cross-link ratio and mesh size, this is the first application of this methodology for polyacrylamide hydrogels. By changing the total monomer content in the synthesis solution (%T) from 5 to 30%, at a fixed value of cross-linker content in the total monomer amount (%C) of 5%, the final parameter obtained, the mesh size, can be tuned from 2 to 0.3 nm. It was also possible to change the mesh size (0.19-0.35) by varying %C from 5 to 12% (at %T = 20%). Scanning Electron Microscopy images for the most different formulations are shown and corroborate data obtained from the theory. (c) 2008 Elsevier Ltd. All rights reserved.

Thermoanalytical Characterization and Dissolution Profiles Studies of Metronidazole Tablets

In the present study dissolution tests and thermoanalytical (TA) techniques were applied to metronidazole tablets from five laboratories (R, G, SA, SB, SC) available on the Brazilian market. The TA profiles indicated that in some formulations interactions between components led to eutectic products with lower melting points than metronidazole. The formulations SB and SC showed dissolution profiles that did not agree with published standards, confirming the TA results. All dissolution data were mathematically compared with kinetic models of release, demonstrating the main release mechanism was first order in all the tablets. The formulations were statistically compared by ANOVA and post-hoc tests (Tukey and Newman-Keuls), reveling significant differences in dissolution efficiency (DE).

Flow injection analysis using carbon film resistor electrodes for amperometric determination of ambroxol

Flow injection analysis (FIA) using a carbon film sensor for amperometric detection was explored for ambroxol analysis in pharmaceutical formulations. The specially designed flow cell designed in the lab generated sharp and reproducible current peaks, with a wide linear dynamic range from 5 x 10(-7) to 3.5 x 10(-4) mol L-1, in 0.1 mol L-1 sulfuric acid electrolyte, as well as high sensitivity, 0.110 A mol(-1) L cm(-2) at the optimized flow rate. A detection limit of 7.6 x 10(-8) mol L-1 and a sampling frequency of 50 determinations per hour were achieved, employing injected volumes of 100 mu L and a flow rate of 2.0 mL min(-1). The repeatability, expressed as R.S.D. for successive and alternated injections of 6.0 x 10(-6) and 6.0 x 10(-5) mol L-1 ambroxol solutions, was 3.0 and 1.5%, respectively, without any noticeable memory effect between injections. The proposed method was applied to the analysis of ambroxol in pharmaceutical samples and the results obtained were compared with UV spectrophotometric and acid-base titrimetric methods. Good agreement between the results utilizing the three methods and the labeled values was achieved, corroborating the good performance of the proposed electrochemical methodology for ambroxol analysis. (C) 2008 Elsevier B.V. All rights reserved.

Determination of ciclopirox olamine in pharmaceutical products by capillary electrophoresis with capacitively coupled contactless conductivity detection

This paper describes the determination of ciclopirox olamine in pharmaceutical formulations using capillary electrophoresis with capacitively coupled contactless conductivity detection. In an alkaline medium, ciclopirox olamine is converted into an anionic species and its detection is possible in capillary electrophoresis with capacitively coupled contactless conductivity detection without an electroosmotic flow modifier, because it is a low-mobility species. A linear working range from 2.64 to 264 mu g/mL in sodium hydroxide electrolyte as well as low detection limit (0.39 mu g/mL) and a good repeatability (RSD = 3.4% for 264 mu g/mL ciclopirox solution (n = 10)) were achieved. It was also possible to determine olamine in its cationic form when acetic acid was used as the electrolyte solution. The results obtained include a linear range from 26.4 to 184.8 mu g/mL and a detection limit of 2.6 mu g/mL olamine. The proposed methods were applied to the analysis of commercial pharmaceutical products and the results were compared with the values indicated by the manufacturer as well as those obtained using a titrimetric method recommended by American Pharmacopoeia.

Quantification of N-acetylcysteine in pharmaceuticals using cobalt phthalocyanine modified graphite electrodes

Flow injection analysis (FIA) with amperometric detection was employed for the quantification of N-acetylcysteine (NAC) in pharmaceutical formulations, utilizing an ordinary pyrolytic graphite (OPG) electrode modified with cobalt phthalocyanine (CoPc). Cyclic voltammetry was used in preliminary studies to establish the best conditions for NAC analysis. In FIA-amperometric experiments the OPG-CoPc electrode exhibited sharp and reproducible current peaks over a wide linear working range (5.0 x 10(-5)-1.0 x 10(-3) mol L(-1)) in 0.1 mol L(-1) NaOH solution. High sensitivity (130 mA mol(-1) cm(2)) and a low detection limit (9.0 x 10(-7) mol L(-1)) were achieved using the sensor. The repeatability (R.S.D.%) for 13 successive flow injections of a solution containing 5.0 x 10(-4) mol L(-1) NAC was 1.1%. The new procedure was applied in analyses of commercial pharmaceutical products and the results were in excellent agreement with those obtained using the official titrimetric method. The proposed amperometric method is highly suitable for quality control analyses of NAC in pharmaceuticals since it is rapid, precise and requires much less work than the recommended titrimetric method. (C) 2010 Elsevier B.V. All rights reserved.

Nasal immunization of mice with Lactobacillus casei expressing the Pneumococcal Surface Protein A: induction of antibodies, complement deposition and partial protection against Streptococcus pneumoniae challenge

Strategies for the development of new vaccines against Streptococcus pneumoniae infections try to overcome problems such as serotype coverage and high costs, present in currently available vaccines. Formulations based on protein candidates that can induce protection in animal models have been pointed as good alternatives. Among them, the Pneumococcal Surface Protein A (PspA) plays an important role during systemic infection at least in part through the inhibition of complement deposition on the pneumococcal surface, a mechanism of evasion from the immune system. Antigen delivery systems based on live recombinant lactic acid bacteria (LAB) represents a promising strategy for mucosal vaccination, since they are generally regarded as safe bacteria able to elicit both systemic and mucosal immune responses. In this work, the N-terminal region of clade I PspA was constitutively expressed in Lactobacillus casei and the recombinant bacteria was tested as a mucosal vaccine in mice. Nasal immunization with L. casei-PspA 1 induced anti-PspA antibodies that were able to bind to pneumococcal strains carrying both clade 1 and clade 2 PspAs and to induce complement deposition on the surface of the bacteria. In addition, an increase in survival of immunized mice after a systemic challenge with a virulent pneumococcal strain was observed. (C) 2008 Elsevier Masson SAS. All rights reserved.

Electroanalytical Method for the Analysis of Methyldopa In Pharmaceutical Tablets Using a Crude Extract of Laccase from Pycnoporus sanguineus as Oxidizing Agent

Several colorimetric and chromatographic methods have been used for the identification and quantification of methyldopa (MA) in pharmaceutical formulations and clinical samples. However, these methods are time- and reagent-consuming, which stimulated our efforts to develop a simple, fast, and low-cost alternative method. We carried out an electroanalytical method for the determination of MA in pharmaceutical formulations using the crude enzymatic extract of laccase from Pycnoporus sanguineus as oxidizing agent. This method is based on the biochemical oxidation of MA by laccase (LAC), both in solution, followed by electrochemical reduction on glassy carbon electrode surface. This method was employed for the determination of MA in pure and pharmaceutical formulations and compared with the results obtained using the official method. A wide linear curve from 23 x 10(-5) to 1 x 10(-4) mol L(-1) was found with a detection limit calculated from 43 x 10(-6) mol L(-1).

A Graphite-Polyurethane Composite Electrode for the Analysis of Furosemide

A graphite-polyurethane composite electrode has been used for the determination of furosemide, a antihypertensive drug, in pharmaceutical samples by anodic oxidation. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrooxidation process at +1.0 V vs. SCE over a wide pH range, with the result that no adsorption of analyte or products occurs, unlike at other carbon-based electrode materials. Quantification was carried out using cyclic voltammetry, differential pulse voltammetry, and square-wave voltammetry. Linear ranges were determined (up to 21 mu mol L-1 with cyclic voltammetry) as well as limits of detection (0.15 mu mol L-1 by differential pulse voltammetry). Four different types of commercial samples were successfully analyzed. Recovery tests were performed which agreed with those obtained by spectrophotometric evaluation. The advantages of this electrode material for repetitive analyzes, due to the fact that no electrode surface renewal is needed owing to the lack of adsorption, are highlighted.

Characterization of protein hydrolysates of cosmetic use by CE-MS

Protein hydrolysates have been used as active principles in cosmetic products conferring different properties to the final formulations, which are mostly controlled by the peptide size and its amino acid sequence. In this work, capillary electrophoresis coupled to mass spectrometry analyses were carried out in order to investigate such characteristics of protein hydrolysates. Samples of different origins (milk, soy and rice) were obtained from a local company, and were analyzed without a previous preparation step. The background electrolyte (BGE) and sheath liquid compositions were optimized for each sample. The best BGE composition (860 mmol/L formic acid - pH 1.8 - in 70: 30 v/v water/methanol hydro-organic solvent) was chosen based on the overall peak resolution whereas the best sheath liquid was selected based on increased sensitivity and presented different compositions to each sample (10.9-217 mmol/L formic acid in 75: 25-25: 75 v/v water/methanol hydro-organic solvent). Most of the putative peptides in the hydrolysate samples under investigation presented molecular masses of 1000 Da or less. De novo sequencing was carried out for some of the analytes, revealing the hydrophobicity/polarity of the peptides. Hence, the technique has proved to be an advantageous tool for the quality control of industrial protein hydrolysates.

Analytical Potentialities of Carbon Nanotube/Silicone Rubber Composite Electrodes: Determination of Propranolol

A new composite electrode based on multiwall carbon nanotubes (MWCNT) and silicone-rubber (SR) was developed and applied to the determination of propranolol in pharmaceutical formulations. The effect of using MWCNT/graphite mixtures in different proportions was also investigated. Cyclic voltammetry and electrochemical impedance spectroscopy were used for electrochemical characterization of different electrode compositions. Propranolol was determined using MWCNT/SR 70% (m/m) electrodes with linear dynamic ranges up to 7.0 mu molL(-1) by differential pulse and up to 5.4 mu molL(-1) by square wave voltammetry, with LODs of 0.12 and 0.078 mu molL(-1), respectively. Analysis of commercial samples agreed with that obtained by the official spectrophotometric method. The electrode is mechanically robust and presented reproducible results and a long useful life.

Evaluation of Postpolymerization as a Function of the Storage Time of Triethylene Glycol Dimethacrylate/2,2-Bis[4-(2-Hydroxy-3-Methacryloxy-Prop-1-Oxy)-Phenyl]-propane Bisphenyl-alpha-Glycidyl Ether Dimethacrylate Copolymers Used in Dental Resins by Differential Scanning Calorimetry and Dynamic Mechanical Analysis

The aim of this work was to evaluate the effect of the storage time on the thermal properties of triethylene glycol dimethacrylate/2,2-bis[4-(2-hydroxy-3-methacryloxy-prop-1-oxy)-phenyl]propane bisphenyl-alpha-glycidyl ether dimethacrylate (TB) copolymers used in formulations of dental resins after photopolymerization. The TB copolymers were prepared by photopolymerization with an Ultrablue IS light-emitting diode, stored in the dark for 160 days at 37 degrees C, and characterized with differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and Fourier transform infrared spectroscopy with attenuated total reflection. DSC curves indicated the presence of an exothermic peak, confirming that the reaction was not completed during the photopolymerization process. This exothermic peak became smaller as a function of the storage time and was shifted at higher temperatures. In DMA studies, a plot of the loss tangent versus the temperature initially showed the presence of two well-defined peaks. The presence of both peaks confirmed the presence of residual monomers that were not converted during the photopolymerization process. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 679-684, 2009

Experimentell studie på kostnadseffektiva inkjetbestrykningspigment

The objective of this study was to evaluate and compare the print performance of some of the new most promising, cost effective absorbent pigments specialised for inkjet coatings on the market in a continuous drive to find an alternative to silica. The target was a lower production cost for ArjoWiggins inkjet products, OMD 01 and OMD 02. Five absorbent pigments are being evaluated through measuring the qualities of the coating mix itself, visual evaluations of print performance and physical testing of the coated paper. Pigments 1,2 and 3, which all are said to be tailored for inkjet coatings, did not reach the print performance needed for an OMD 01 and OMD 02 equal, due to severe bleed and feathering identified especially on the Epson 950 printer. They are therefore currently not seen as viable formulations. A blend of 50% pigment 5 and 50% silica had excellent print performance as OMD 01 and OMD 02 equivalents and is therefore recommended as a potential alternative to 100% silica. It is of the company’s interest to find a more cost effective solution to their inkjet coatings, and a 50/50 blend of Pigment 5 will save the company more than 35 000 euro per year.