Maria Irene Yoshida

Federal University of Minas Gerais, Cidade de Minas, Minas Gerais, Brazil

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Publications (51)81.42 Total impact

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    ABSTRACT: The role of chemical and mineralogical soil properties in the retention and oxidation of atmospheric mercury in tropical soils is discussed based on thermal desorption analysis. The retention of gaseous mercury by tropical soils varied greatly both quantitatively and qualitatively with soil type. The average natural mercury content of soils was 0.08±0.06μgg(-1) with a maximum of 0.215±0.009μgg(-1). After gaseous Hg(0) incubation experiments, mercury content of investigated soils ranged from 0.6±0.2 to 735±23μgg(-1), with a mean value of 44±146μgg(-1). Comparatively, A horizon of almost all soil types adsorbed more mercury than B horizon from the same soil, which demonstrates the key role of organic matter in mercury adsorption. In addition to organic matter, pH and CEC also appear to be important soil characteristics for the adsorption of mercury. All thermograms showed Hg(2+) peaks, which were predominant in most of them, indicating that elemental mercury oxidized in tropical soils. After four months of incubation, the thermograms showed oxidation levels from 70% to 100%. As none of the samples presented only the Hg(0) peak, and the soils retained varying amounts of mercury despite exposure under the same incubation conditions, it became clear that oxidation occurred on soil surface. Organic matter seemed to play a key role in mercury oxidation through complexation/stabilization of the oxidized forms. The lower percentages of available mercury (extracted with KNO3) in A horizons when compared to B horizons support this idea. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Chemosphere 05/2015; 134:181-191. DOI:10.1016/j.chemosphere.2015.04.020 · 3.50 Impact Factor
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    ABSTRACT: Topical therapy is the first choice for the treatment of mild to moderate acne and all-trans retinoic acid is one of the most used drugs. The combination of retinoids and antimicrobials is an innovative approach for acne therapy. Recently, lauric acid, a saturated fatty acid, has shown strong antimicrobial activity against Propionibacterium acnes. However, topical application of retinoic acid is followed by high incidence of side-effects, including erythema and irritation. Solid lipid nanoparticles represent an alternative to overcome these side-effects. This work aims to develop solid lipid nanoparticles loaded with retinoic acid and lauric acid and evaluate their antibacterial activity. The influence of lipophilic stearylamine on the characteristics of solid lipid nanoparticles was investigated. Solid lipid nanoparticles were characterized for size, zeta potential, encapsulation efficiency, differential scanning calorimetry and X-ray diffraction. The in vitro inhibitory activity of retinoic acidlauric acid-loaded solid lipid nanoparticles was evaluated against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. High encapsulation efficiency was obtained at initial time (94±7% and 100±4% for retinoic acid and lauric acid, respectively) and it was demonstrated that lauric acid-loaded-solid lipid nanoparticles provided the incorporation of retinoic acid. However, the presence of stearylamine is necessary to ensure stability of encapsulation. Moreover, retinoic acid-lauric acid-loaded solid lipid nanoparticles showed growth inhibitory activity against Staphylococcus epidermidis, Propionibacterium acnes and Staphylococcus aureus, representing an interesting alternative for the topical therapy of acne vulgaris.
    Journal of Nanoscience and Nanotechnology 01/2015; 15(1). DOI:10.1166/jnn.2015.9184 · 1.34 Impact Factor
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    ABSTRACT: In the present study were evaluated the compatibility of ciprofibrate (CIP) with pharmaceutical excipients usually used in the solid forms by analytical techniques. Binary mixtures with pharmaceutical excipients were examined by Differential Screening Calorimetry (DSC) initially used to assess compatibility of mixtures of CIP and each selected excipients in a 1:1 (w/w) physical mixtures. The Fourier Transform Infrared (FTIR) spectroscopy and X-ray Powder Diffractometry were used to provide a complete investigation of the binary mixtures. The CIP:hydroxypropylmethylcellulose mixture displayed some physical interaction based on the DSC results, but the FTIR study ruled out any chemical change. The binary mixture with microcrystalline cellulose showed changes in the XRDP. Keywords: Ciprofibrate. Drug-excipient interaction. Thermal analysis. FTIR. XRPD.
    IX Brazilian Congress in Thermal Analysis and Calorimetry, Serra Negra - São Paulo; 11/2014
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    ABSTRACT: Hydrochlorothiazide is a diuretic used to treat hypertension that belongs to class IV of the Biopharmaceutics Classification System. The drug was evaluated by quality control, thermal characterization tests, and pharmaceutical formulation compatibility studies. It was concluded that the generic drug, Lab 2, was not a pharmaceutical equivalent. The compounded drugs, Lab 5 and Lab 6, produced unsatisfactory but expected results, since there is no requirement for dissolution and dissolution profile testing for the commercialization of these products. In a compatibility study, lactose and mannitol were shown to be incompatible with HCTZ, which may explain the lack of equivalence of the generic pharmaceutical product, associated with other situations.
    Molecules 10/2014; 19(10):16824-36. DOI:10.3390/molecules191016824 · 2.42 Impact Factor
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    ABSTRACT: In this study, the physical and thermal properties of essential oil microparticles of oregano (Origanum vulgare L.) dried via spray drying were examined. The product was characterized by morphology, mean diameter, particle size distribution, moisture sorption curve, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The process promoted the formation of spherical capsules with high polydispersity. The isotherm exhibited type II behavior (sigmoidal curve), and the best fit was obtained by the Guggenheim–Anderson–de Boer (GAB) model (E = 6.748%). The DSC analysis showed that the increase equilibrium moisture content reduced the Tg value of the microparticles (164.47–91.29C). The samples stored at low humidity resulted in more thermally stable particles, and the samples with equilibrium moisture content of 4.74% showed higher thermal stability.Practical ApplicationsThe applications of essential oils with relevant antioxidant activities, such as oregano essential oil, as a food additive is limited in the conventional form, due to their fast degradation triggered by temperature, light, presence of oxygen and humidity, among others. The encapsulation technique by spray drying has been successfully used to overcome this drawback. However, the spray-dried products may present some technological problems, such as high hygroscopicity and low resistance when subjected to high temperatures. The evaluation of microparticle stability is a relevant and important issue when desiring to ensure their quality and application. Studies of the functional properties such as hygroscopicity, sorption behavior and thermal resistance determine the ideal conditions for the storage of this type of product.
    Journal of Food Process Engineering 10/2014; 38(1). DOI:10.1111/jfpe.12120 · 0.63 Impact Factor
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    ABSTRACT: This study was conducted to evaluate the effects of the partial substitution of whey protein isolate (WPI) by inulin (IN) or maltodextrin (MD) as wall materials on the characteristics of microparticles containing fish produced by spray drying. Three treatments, WPI, WPI/MD (1:1) and WPI/IN (1:1), were evaluated in a completely randomised design with three replicates. The solubility and hygroscopicity of the particles were not affected by the wall material, attaining average values of 79% and 5.5 g.100g- 1, respectively. The partial substitution of WPI by inulin improved the wettability properties of the powders and reduced the occurrence of surface oil on the particles. The surface oil content was 5.6%, 6.5% and 7.7% for the particles produced using WPI/IN, WPI/MD and WPI, respectively. The particles presented smoother surfaces, with a smaller number of folds, when inulin was present. The GAB model was chosen as the model best adjusted to the isotherms, with values of moisture content on the monolayer (Xm) equal to 0.036 g.g- 1, 0.026 g.g- 1 and 0.074 g.g- 1 for the WPI, WPI/MD and WPI/IN microparticles, respectively. All of the powders obtained from these treatments exhibited a no crystalline structure, and the glass transition temperatures of these anhydrous powders were 168 °C, 149 °C and 131 °C for the WPI, WPI/MD and WPI/IN microparticles, respectively. The use of inulin and maltodextrin proved to be good alternatives secondary wall materials for fish oil together with WPI.
    Food Research International 08/2014; 62. DOI:10.1016/j.foodres.2014.02.003 · 3.05 Impact Factor
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    ABSTRACT: The purpose of the present study was to develop and assess a novel sustained-release drug delivery system of Bimatoprost (BIM). Chitosan polymeric inserts were prepared using the solvent casting method and characterized by swelling studies, infrared spectroscopy, differential scanning calorimetry, drug content, scanning electron microscopy and in vitro drug release. Biodistribution of 99mTc-BIM eye drops and 99mTc-BIM-loaded inserts, after ocular administration in Wistar rats, was accessed by ex vivo radiation counting. The inserts were evaluated for their therapeutic efficacy in glaucomatous Wistar rats. Glaucoma was induced by weekly intracameral injection of hyaluronic acid. BIM-loaded inserts (equivalent to 9.0 µg BIM) were administered once into conjunctival sac, after ocular hypertension confirmation. BIM eye drop was topically instilled in a second group of glaucomatous rats for 15 days days, while placebo inserts were administered once in a third group. An untreated glaucomatous group was used as control. Intraocular pressure (IOP) was monitored for four consecutive weeks after treatment began. At the end of the experiment, retinal ganglion cells and optic nerve head cupping were evaluated in the histological eye sections. Characterization results revealed that the drug physically interacted, but did not chemically react with the polymeric matrix. Inserts sustainedly released BIM in vitro during 8 hours. Biodistribution studies showed that the amount of 99mTc-BIM that remained in the eye was significantly lower after eye drop instillation than after chitosan insert implantation. BIM-loaded inserts lowered IOP for 4 weeks, after one application, while IOP values remained significantly high for the placebo and untreated groups. Eye drops were only effective during the daily treatment period. IOP results were reflected in RGC counting and optic nerve head cupping damage. BIM-loaded inserts provided sustained release of BIM and seem to be a promising system for glaucoma management.
    PLoS ONE 04/2014; 9(4):e95461. DOI:10.1371/journal.pone.0095461 · 3.53 Impact Factor
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    ABSTRACT: Viscoelastic polyurethane (PU) foams based on modified tung oil, ethylene glycol and polymeric MDI, and reinforced with rice husk ash (RHA), were prepared by a free-rise pouring method and characterized in terms of density, compression and dynamic mechanical behavior. The density of foams ranged between 50 and 90 kg/m3, depending on the position of the sample with respect to the foam rise direction and filler content. As revealed by dynamic mechanical tests, the foams exhibited two different and broad thermal transitions, the temperature of their maxima depending on filler concentration. Compression modulus, compressive strength and storage modulus increase as foam density increases but decreases as rice husk ash concentration increases due to the detrimental changes induced by the filler in the foam cellular structure. However, densification strain exhibits the opposite behavior, indicating that reinforced foams can sustain slightly higher deformations without collapsing, probably due to a reduced reactivity of the components induced by the filler.
    Polymer Testing 06/2013; 32(4):665–672. DOI:10.1016/j.polymertesting.2013.03.010 · 1.82 Impact Factor
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    ABSTRACT: The Co{[14HBDC][14BDC]0,5[INH]} (1) coordination polymer was synthesised by a solvothermal route using the ligands 1,4-benzenedicarboxylic acid [14BDC], isonicotinylhydrazine [INH] and Co(NO3)·6H2O. It was characterised by elemental analysis (CHN), infrared vibrational spectroscopy, thermal analysis (TGA, DrTGA and DSC) and single-crystal X-ray diffraction analysis. In this coordination polymer, the ligand INH is coordinated to the metal site in two ways, acting as a bridging ligand. Unlike INH, 14BDC acts as a bridging ligand between two metal sites, coordinated in a bidentate manner, and between a metal site by a carboxyl group. According to the X-ray diffraction analysis, this compound is an interpenetrated 2D coordination polymer with pores along the crystallographic axis c. These small pores have interesting potential application in the adsorption of small gas molecules, such as H2.
    Inorganica Chimica Acta 06/2013; 402:60–68. DOI:10.1016/j.ica.2013.03.038 · 2.04 Impact Factor
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    ABSTRACT: A chemically modified tung oil was used as the main polyol component in the formulation of viscoelastic (low resilience) polyurethane foams. Rice Husk Ash (RHA), a residue from the rice process industry, was chosen to be incorporated as rigid filler in these materials because of its high silica content. Water was used as blowing agent in order to increase the green nature of the reinforced foams. Physico-chemical and thermal properties of the neat and reinforced foams were measured and analyzed. RHA addition leads to noticeable changes in several properties, mainly thermal conductivity, density and foam morphology, even at the low filler content used in this work. Although the thermal stability was almost unaffected by ash content, a stabilizing effect of the inorganic filler was identified, since the residual char was higher than predicted from theoretical calculations.
    Polymer Testing 04/2013; 32(2):438–445. DOI:10.1016/j.polymertesting.2013.01.002 · 1.82 Impact Factor
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    ABSTRACT: Atorvastatin is an antilipemic drug belonging to the statins class, whose reference drug is Pfizer's Lipitor®. It is used to reduce the levels of lipoproteins rich in cholesterol and reduce the risk of coronary artery disease. It is well-known that calcium atorvastatin (ATV), C(66)H(68)CaF(2)N(4)O(10)•3H(2)O, presents polymorphism. The drug in question is commonly sought after by pharmaceutical industries that produce generic drugs, due to the fact that the drug has a high value price, it is consumed globally, and its patent expired in late 2010. Many questions concerning this drug's pharmaceutical scope demonstrate its importance regarding stability studies and the identification of degradation products of drugs and pharmaceutical formulations. ATV has been found to degrade under acid and basic conditions, including a first order kinetic degradation under acid conditions, as compared to a zero order kinetic degradation under basic conditions, which tends to be less stable when studied within acid mediums. The rate constant (k) for degradation in acid medium was 1.88 × 10-2 s-1 (first order), while for basic medium k = 2.35 × 10-4 mol L-1 s-1 (zero order), demonstrating a lower stability of the drug within acid mediums.
    Molecules 02/2013; 18(2):1447-56. DOI:10.3390/molecules18021447 · 2.42 Impact Factor
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    ABSTRACT: Two new coordination polymers {[Co(μ-4,4′-dps)2(H2O)2](NO3)2·2(4,4′-dps)·4H2O}n (1) and {[Cu(μ-4,4′-dps)2(H2O)2](NO3)2·2H2O}n (2) [4,4′-dps = di(4-pyridyl)sulfide] have been synthesized by solvothermal reactions between the nitrate salts of cobalt(II) (1) and copper(II) (2) and the 4,4′-dps molecule. Compounds 1 and 2 have been characterized by elemental analysis, thermal analysis (TG/DTA), vibrational spectroscopy, single crystal X-ray diffraction analysis and variable-temperature magnetic measurements. Compounds 1 and 2 are cationic chain compounds of formula {[M(μ-4,4′-dps)2(H2O)2]n2n+ [M = Co(II) (1) and Cu(II) (2)] with double 4,4′-dps bridges, uncoordinated nitrate anions, and crystallization water (1 and 2) and 4,4′-dps (1) molecules. Each metal ion in 1 and 2 is six-coordinated with two coordinated water molecules in trans position and four pyridyl-nitrogen atoms from four 4,4′-dps ligands building a distorted octahedral environment. The values of the intrachain metal–metal separation are 9.940(4) and 9.702(4) Å for 1 and 2, respectively. The magnetic properties of 1 and 2 correspond to those of magnetically isolated copper(II) and high-spin cobalt(II) centers, the extended 4,4′-dps bridge being a poor mediator of magnetic interactions.
    Polyhedron 09/2012; 45(1):1-8. DOI:10.1016/j.poly.2012.07.045 · 2.05 Impact Factor
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    ABSTRACT: The classical method of melting lead by fire-assay (Pb-FA) is the most frequently used analytical technique in gold prospection. The crucible solid waste which is generated in this process is usually characterized by chemical and mineralogical composition, granulometric size distribution, and classified according to Brazilian Environmental Regulations. This study demonstrates how acid leaching can be used to remove lead from waste originally classified as hazardous by treatment with hydrochloric and nitric acids followed by chemical precipitation in sodium metasilicate solution. It is shown that for every 1000 kg of hazardous waste, 995.6 kg of non-harzardous waste can be recovered.
    Journal of Environmental Management 07/2012; 110:110-5. DOI:10.1016/j.jenvman.2012.06.028 · 3.19 Impact Factor
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    ABSTRACT: Cationic Mn porphyrins are among the most potent catalytic antioxidants and/or cellular redox modulators. Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin chloride (MnTE-2-PyPCl(5)) is the Mn porphyrin most studied in vivo and has successfully rescued animal models of a variety of oxidative stress-related diseases. The stability of an authentic MnTE-2-PyPCl(5) sample was investigated hereon by thermogravimetric, derivative thermogravimetric, and differential thermal analyses (TG/DTG/DTA), under dynamic air, followed by studies at selected temperatures to evaluate the decomposition path and appropriate conditions for storage and handling of these materials. All residues were analyzed by thin-layer chromatography (TLC) and UV-vis spectroscopy. Three thermal processes were observed by TG/DTG. The first event (endothermic) corresponded to dehydration, and did not alter the MnTE-2-PyPCl(5) moiety. The second event (endothermic) corresponded to the loss of EtCl (dealkylation), which was characterized by gas chromatography-mass spectrometry. The residue at 279°C had UV-vis and TLC data consistent with those of the authentic, completely dealkylated analog, MnT-2-PyPCl. The final, multi-step event corresponded to the loss of the remaining organic matter to yield Mn(3)O(4) which was characterized by IR spectroscopy. Isothermal treatment at 188°C under static air for 3h yielded a mixture of partially dealkylated MnPs and traces of the free-base, dealkylated ligand, H(2)T-2-PyP, which reveals that dealkylation is accompanied by thermal demetallation under static air conditions. Dealkylation was not observed if the sample was heated as a solid or in aqueous solution up to ∼100°C. Whereas moderate heating changes sample composition by loss of H(2)O, the dehydrated sample is indistinguishable from the original sample upon dissolution in water, which indicates that catalytic activity (on Mn basis) remains unaltered. Evidently, dealkylation at high temperature compromises sample activity.
    Journal of pharmaceutical and biomedical analysis 03/2012; DOI:10.1016/j.jpba.2012.03.033 · 2.83 Impact Factor
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    ABSTRACT: Chitosan, a cationic polysaccharide biopolymer with mucoadhesive properties, presents a promising future in the prolonged ocular delivery of drugs. The present study compared the efficacy and safety of chitosan-coated timolol maleate (TM) mucoadhesive film, using a 0.5% TM commercial ophthalmic solution in a rabbit model. In addition, this study investigates the maximum release time of these implants in vivo. The mucoadhesive films were prepared by means of a casting and solvent evaporation technique performed in a 2 wt% acetic acid solution and distilled water. Physical properties were characterized by release and swelling studies, differential scanning calorimetry, and attenuated total reflectance fourier transformed infrared spectroscopy (ATR-FTIR). The developed formulations were evaluated for their pharmacodynamics in ocular normotensive albino rabbits, in which the intraocular pressure (IOP) was measured by means of applanation tonometer on alternative days (13 h) for 11 weeks. For 15 days, 0.5% TM commercial ophthalmic solution was administered twice a day (n=5) and compared to chitosan-coated TM (n=5). In the control group (n=5), saline was used twice a day. The maximum TM release time from chitosan films were also recorded. After euthanasia, the right eyes were removed from the 3 groups for histological analyses. In an in vitro study, TM was released over a 4-week period, in which 85% of the drug was released over the first 2 weeks. However, the film's release of TM lowered the in vivo IOP levels over a 10-week period. No significant difference in the lowering of IOP in rabbits treated with 0.5% TM commercial ophthalmic solution, as compared to those that received the films (P<0.05), could be observed. No signs of ocular discomfort or irritations could be identified upon ophthalmic examination by slit-lamp biomicroscopy. Ophthalmic structures that came in direct contact with the films revealed no alterations within the histopathological studies. Moreover, the animals showed no signs of ocular discomfort during the experimental assays. These findings suggest that the TM-loaded chitosan film is safe and efficient and presents a promising future as an ocular drug delivery system in the treatment and prevention of glaucoma.
    Journal of ocular pharmacology and therapeutics: the official journal of the Association for Ocular Pharmacology and Therapeutics 02/2012; 28(4):350-8. DOI:10.1089/jop.2011.0174 · 1.42 Impact Factor
  • ABRATEC - VIII Brazilian Congress and III Pan-American Congress on Thermal Analysis and Calorimetry, Campos do Jordão; 01/2012
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    ABSTRACT: In this study we prepared an inclusion complex between an iodide analogue of metronidazole (MTZ-I) and cyclodextrin (CD) to develop a safer and more effective method of treating Trypanosoma cruzi infections. According to our results, MTZ-I and MTZ-I:β-CD were 10 times more active than MTZ, demonstrating that the presence of an iodine atom on the side chain increased the trypanocidal activity while maintaining its cytotoxicity. The selective index shows that MTZ-I was 10 times more active against T. cruzi than it was against mammalian cells. The modification of MTZ side chains provides a promising avenue for the development of new drugs.
    Memórias do Instituto Oswaldo Cruz 12/2011; 106(8):1055-7. DOI:10.1590/S0074-02762011000800027 · 1.57 Impact Factor
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    ABSTRACT: In this study, an analytical method was developed and validated for quantitation of the drug bevacizumab (Avastin®) by high performance liquid chromatography (HPLC). The HPLC column was a BioSuite 250® HR SEC, 300 x 7.8 mm x 5 µm (Waters, USA). The mobile phase consisted of phosphate buffered saline (PBS). The results revealed that the method was specific, precise, accurate, robust and linear (r2 = 0.998) from 5 to 75 µg mL-1. Therefore, this method can be used in drug release studies or in quality control ampoules of the drug.
    Química Nova 12/2011; 35(3):608-611. DOI:10.1590/S0100-40422012000300029 · 0.66 Impact Factor