990 resultados para Spectrophotometry
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This study evaluated the cytotoxic effects of 2 mineral trioxide aggregate (MTA) cements - White-MTA-Angelus and a new formulation, MTA-Bio - on odontoblast-like cell (MDPC-23) cultures. Twenty-four disc-shaped (2 mm diameter x 2 mm thick) specimens were fabricated from each material and immersed individually in wells containing 1 mL of DMEM culture medium for either 24 h or 7 days to obtain extracts, giving rise to 4 groups of 12 specimens each: G1 - White-MTA/24 h; G2 - White-MTA/7 days; G3 - MTA-Bio/24 h; and G4 - MTA-Bio/7 days. Plain culture medium (DMEM) was used as a negative control (G5). Cells at 30,000 cells/cm 2 concentration were seeded in the wells of 24-well plates and incubated in a humidified incubator with 5% CO 2 and 95% air at 37°C for 72 h. After this period, the culture medium of each well was replaced by 1 mL of extract (or plain DMEM in the control group) and the cells were incubated for additional 2 h. Cell metabolism was evaluated by the MTT assay and the data were analyzed statistically by ANOVA and Tukey's test (α=0.05). Cell morphology and the surface of representative MTA specimens of each group were examined by scanning electron microscopy. There was no statistically significant difference (p>0.05) between G1 and G2 or between G3 and G4. No significant difference (p>0.05) was found between the experimental and control groups either. Similar cell organization and morphology were observed in all groups, regardless of the storage periods. However, the number of cells observed in the experimental groups decreased compared to the control group. MTA-Bio presented irregular surface with more porosities than White-MTA. In conclusion, White-MTA and MTA-Bio presented low cytotoxic effects on odontoblast-like cell (MDPC-23) cultures.
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This study describes the chemical and physical-chemical profile of plant drug and ethanolic extract obtained from fruits of Solanum lycocarpum A. St.-Hill. (Solanaceae). The physical and chemical analysis involved the granulometry determination, non-compacted apparent density, loss on drying in oven and in infrared scale, pH, ash values and extractive values. The results determined the physical-chemical characteristics of the drug plant. It was also carried out the microbiological control of the plant drug. The preliminary phytochemical screening featured the presence of tannins, flavonoids and saponins in the plant drug and alkaloids and steroids in the ethanolic exctract. The solamargine and solasonine glycoalkaloids were identified through TLC and GC/ MS. The levels of total phenols and tannins were quantified in the extract (8.90% and 6,85% respectively). Such studies contribute to the chemical identification and quality control of S. lycocarpum fruits. © 2010 Phcog.net.
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The aim of this study was to determine the serum concentrations of immunoglobulin G, TP and the γ globulin electrophoretic fraction, as well as the enzymatic activities of GGT and ALP. This was done in order to explore the possibility of using changes in activities of these enzymes as indirect indicators of adequate humoral immunity and/ or failure of immune passive transfer in lambs. Pearson correlation was performed between variable of four groups of age during the first 30 days of life. Blood samples (191) from lambs from 21 different farms in Araçatuba region- São Paulo. The following tests were perfomed: radial immunodiffusion, spectrophotometry and electrophoresis to stain the amount of IgG, TP and γ globulin, respectively. GGT and ALP values were determinate using commercial kits. There was a statistically significant correlation between ALP and GGT. The same correlation was observed from TP, IgG and GGT. A positive γ globulin correlation was found between GGT, IgG and TP. ALP activity cannot be used as an indicator of immune passive transfer.
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Indigo carmine forms a stable complex with different ions, and the stability constant of the complexes were evaluated as log K equal to 5.75; 5.00; 4.89 and 3.89 for complexes with Cu(II), Ni(II), Co(II) and Zn(II) ions, respectively, in 0.1 mol L -1 carbonate buffer solution at pH 10. The interaction between Cu(II) ions and indigo carmine (IC) in alkaline medium resulted in the formation of the Cu 2(IC) complex, measured by the spectrophotometric method, with a stoichiometric ratio between indigo carmine and metal ions of 2:1 (metal-ligand). The reported method has also been successfully tested for determination of copper in pharmaceutical compounds based on copper-gluconate without pre-treatment.
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The intension of this paper was to review and discuss some of the current quantitative analytical procedures which are used for quality control of pharmaceutical products. The selected papers were organized according to the analytical technique employed. Several techniques like ultraviolet/visible spectrophotometry, fluorimetry, titrimetry, electroanalytical techniques, chromatographic methods (thin-layer chromatography, gas chromatography and high-performance liquid chromatography), capillary electrophoresis and vibrational spectroscopies are the main techniques that have been used for the quantitative analysis of pharmaceutical compounds. In conclusion, although simple techniques such as UV/VIS spectrophotometry and TLC are still extensively employed, HPLC is the most popular instrumental technique used for the analysis of pharmaceuticals. Besides, a review of recent works in the area of pharmaceutical analysis showed a trend in the application of techniques increasingly rapid such as ultra performance liquid chromatography and the use of sensitive and specific detectors as mass spectrometers.
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The present literature review highlights the importance of carotenoids as bioactive compound, and its potential application in functional foods. It were detailed the origin, chemical characteristics and sources of the carotenoids. It were also studied the most used methods to quantify and qualify the carotenoids, including spectrophotometry, mass spectrometry, high-performance liquid chromatography, gas chromatography and colorimetry. The pumpkin intake is recommended because they represent important source of carotenoids such as α-carotene, β-carotene and lutein.
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Triamcinolone (TRI), a drug widely used in the treatment of ocular inflammatory diseases, is practically insoluble in water, which limits its use in eye drops. Cyclodextrins (CDs) have been used to increase the solubility or dissolution rate of drugs. The purpose of the present study was to validate a UV-Vis spectrophotometric method for quantitative analysis of TRI in inclusion complexes with beta-cyclodextrin (B-CD) associated with triethanolamine (TEA) (ternary complex). The proposed analytical method was validated with respect to the parameters established by the Brazilian regulatory National Agency of Sanitary Monitoring (ANVISA). The analytical measurements of absorbance were made at 242nm, at room temperature, in a 1-cm path-length cuvette. The precision and accuracy studies were performed at five concentration levels (4, 8, 12, 18 and 20μg.mL -1). The B-CD associated with TEA did not provoke any alteration in the photochemical behavior of TRI. The results for the measured analytical parameters showed the success of the method. The standard curve was linear (r2 > 0.999) in the concentration range from 2 to 24 μg.mL -1. The method achieved good precision levels in the inter-day (relative standard deviation-RSD <3.4%) and reproducibility (RSD <3.8%) tests. The accuracy was about 80% and the pH changes introduced in the robustness study did not reveal any relevant interference at any of the studied concentrations. The experimental results demonstrate a simple, rapid and affordable UV-Vis spectrophotometric method that could be applied to the quantitation of TRI in this ternary complex.
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Baccharis dracunculifolia DC (Asteraceae) is the main botanical source used by honeybees to produce Brazilian green propolis whose hepatoprotective properties have been already described. In this work we investigated the protective effects of the glycolic extract of B. dracunculifolia (GEBd) against oxidative stress in isolated rat liver mitochondria (RLM). The GEBd was prepared by fractionated percolation using propylene glycol as solvent. The total phenols and flavonoids, which are substances with recognized antioxidant action, were quantified in GEBd and the phytochemical analysis was carried out by HPLC. GEBd exhibited significant scavenger activity towards DPPH radicals and superoxide anions in a concentration-dependent manner, and also a Fe 2+ chelating activity. GEBd decreased the basal H 2O 2 generation and the Fe 2+- or t-BuOOH-induced ROS production in isolated mitochondria. Lipid oxidation of mitochondrial membranes, protein thiol groups and GSH oxidation were also prevented by GEBd. This shows that B. dracunculifolia exhibit potent antioxidant activity protecting liver mitochondria against oxidative damage and such action probably contribute to the antioxidant and hepatoprotective effects of green propolis. © 2011 Elsevier Ltd.
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Introduction: The aim of this study was to evaluate the pH, calcium ion release, setting time, and solubility of white mineral trioxide aggregate (WMTA) and white Portland cement (WPC) combined with the following radiopacifying agents: bismuth oxide (BO), calcium tungstate (CT), and zirconium oxide (ZO). Methods: Fifty acrylic teeth with root-end filling material were immersed in ultrapure water for measurement of pH and calcium release (atomic absorption spectrophotometry) at 3, 24, 72, and 168 hours. For evaluation of setting time, each material was analyzed according to the American Society for Testing and Materials guidelines 266/08. The solubility test was performed according to American National Standards Institute/American Dental Association specification no. 57/2000. Solubility, setting time, and pH values were compared by using analysis of variance and Tukey test, and the values of calcium release were compared by the Kruskal-Wallis and Miller tests. The significance level was set at 5%. Results: The pH and calcium release were higher at 3 and 24 hours. WPC was the material with the higher values for both properties. WMTA had the greatest solubility among all materials (P <.05). All radiopacifiers increased the setting time of WPC, and WMTA had the shortest setting time among all materials (P < .05). Conclusions: All materials released calcium ions. Except for WPC/CT at 168 hours, all materials promoted an alkaline pH. On the basis of the obtained results, ZO and CT can be considered as potential radiopacifying agents to be used in combination with Portland cement. Copyright © 2012 American Association of Endodontists.
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Making an artificial iris with an aesthetically acceptable color is an important aspect of ocular rehabilitation. This work evaluated the influence of different disinfecting solutions on changes to the color of artificial irises used in ocular prostheses. Fifty samples simulating ocular prostheses were produced with cobalt blue artificial irises and divided (n = 10) according to the disinfectant used: neutral soap, Opti-free, Efferdent, 1% hypochlorite, and 4% chlorhexidine. The samples were disinfected for 120 days and subjected to a color readings by spectrophotometry, using the CIE L*a*b* system, before the disinfection period (B), after 60 days of disinfectant exposure (T 1), and after 120 days of disinfectant exposure (T 2). Color differences (ΔE) were calculated for the intervals between T 1 and B (T 1B), and between T 2 and B (T 2B). The data were evaluated by analysis of variance and the Tukey Honestly Significantly Different (α = 0.05). All disinfectant groups exhibited color changes. The mean color change observed for all groups overall during T 2B (ΔE = 3.51) was significantly greater than that observed during T 1B (ΔE = 2.10). All groups exhibited greater color change for the b* values when compared to the a* and L* values. There were no significant differences between the disinfectant groups. It can be concluded that the time period of disinfection and storage significantly affected the stability of artificial iris color, independent of the disinfectant used. © 2012 Wiley Periodicals, Inc.
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Colour stability of resin and silicone is an important factor for longevity of facial prostheses. The aim of this study was to evaluate the colour stability of resins and silicone for facial prostheses. Three brands of acrylic resin and one of facial silicone were evaluated considering pigment incorporation for the colourless materials. Ten samples of each material were fabricated and submitted to measurements of chromatic alteration initially and after 90 and 180 days of weathering natural through visual analysis and spectrophotometry. Data were evaluated by ANOVA and Tukey test (p < 0.05). Statistically significant colour alteration was observed among some materials regardless of the period. The materials did not present a statistical difference between 90 and 180 days except for the pigmented heat-polymerized resin. The colour difference between pigmented Silastic MDX4-4210 and colourless Silastic was statistically significant (p < 0.01) in both periods as well as between pigmented and colourless heat-polymerized resin, and between the resins Rapidaflex and Lentaflex. The visual method demonstrated colour alteration in all materials evaluated during the first 90 days of ageing. All materials exhibited colour alteration due to exposure to environment. © 2012 Informa UK, Ltd.
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Chemical reagents used by the textile industry are very diverse in their composition, ranging from inorganic compounds to polymeric compounds. Strong color is the most notable characteristic of textile effluents, and a large number of processes have been employed for color removal. In recent years, attention has been directed toward various natural solid materials that are able to remove pollutants from contaminated water at low cost, such as sugarcane bagasse. Cell immobilization has emerged as an alternative that offers many advantages in the biodegradation process, including the reuse of immobilized cells and high mechanical strength, which enables metabolic processes to occur under adverse conditions of pH, sterility, and agitation. Support treatment also increases the number of charges on the surface, thereby facilitating cell immobilization processes through adsorption and ionic bonds. Polyethyleneimine (PEI) is a polycationic compound known to have a positive effect on enzyme activity and stability. The aim of the present study was to investigate a low-cost alternative for the biodegradation and bioremediation of textile dyes, analyzing Saccharomyces cerevisiae immobilization in activated bagasse for the promotion of Acid Black 48 dye biodegradation in an aqueous solution. A 1 % concentration of a S. cerevisiae suspension was evaluated to determine cell immobilization rates. Once immobilization was established, biodegradation assays with free and immobilized yeast in PEI-treated sugarcane bagasse were evaluated for 240 h using UV-vis spectrophotometry. The analysis revealed significant relative absorbance values, indicating the occurrence of biodegradation in both treatments. Therefore, S. cerevisiae immobilized in sugarcane bagasse is very attractive for use in biodegradation processes for the treatment of textile effluents. © 2012 Springer Science+Business Media Dordrecht.
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People increasingly desire tooth whitening. Considering the wide range of whitening products on the market, this study evaluated the efficacy of whitening toothpastes and mouth rinses compared with the 10% carbamide peroxide (CP) whitening gel. We obtained 120 cylindrical specimens from bovine teeth, which were darkened for 24 hours in a coffee solution. The color measurement was performed by a spectrophotometer using the CIE L*a*b* system, and specimens were divided into six groups according to the use of the following agents: group 1, conventional fluoridated toothpaste; group 2, Close Up White Now; group 3, Listerine Whitening; group 4, Colgate Plax Whitening; group 5, experimental mouth rinse with Plasdone; and group 6, 10% CP Whiteness Perfect. After the simulation of 12 weeks of treatment for groups 1 to 5 and 14 days of treatment for group 6, the specimens were subjected to a new color reading. Data were subjected to one-way analysis of variance (α=0.05), which showed significant differences among groups after 12 weeks for ΔE (p=0.001). Results of the Tukey test revealed that groups 3, 4, and 6 presented significantly higher color alteration than groups 1, 2, and 5. The whitening toothpaste Close Up White Now and the experimental mouth rinse with Plasdone showed similar color alteration as conventional toothpaste after a 12-week treatment simulation. These groups presented significantly lower color alteration compared with whitening mouth rinses Listerine and Colgate Plax Whitening, which showed similar results to those observed after 14 days of bleaching with 10% CP treatment.
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Background: Several studies seek biological markers that give diagnostic and degree of tumor development. The aim of this study was to validate the determination of plasma DNA using nanotechnology (Nanovue™-NV) in samples of 80 patients with prostate cancer. Methods. Blood samples of 80 patients of the Urology Ambulatory of Faculdade de Medicina do ABC with prostate cancer confirmed by anatomical-pathology criteria were analyzed. DNA extraction was performed using a GFX TM kit (Amersham Pharmacia Biotech, Inc, USA) following the adapted protocol. Plasma was subjected to centrifugation. Results: There was a big difference between the first and the second value obtained by NanoVue Only two samples had no differences between duplicates. Maximum difference between duplicates was 38 μg/mL. Average variation between 51 samples was 10.29 μg/mL, although 21 samples had differences above this average. No correlation was observed between pDNA obtained by traditional spectrophotometry and by nanotechnology. Conclusion: Determination of plasma DNA by nanotechnology was not reproducible. © 2013 Moreno et al; licensee BioMed Central Ltd.
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A disposable pencil graphite electrode modified with dsDNA was used in combination with square wave voltammetry in order to evaluate the interaction of DNA with the textile dyes Disperse Orange 1 (DO1) and Disperse Red 1 (DR1), and with the products of their electrolysis. Significant changes in the characteristic oxidation peaks of the guanine and adenine moieties of immobilized dsDNA were observed after incubation of the modified electrode for 180 s in solutions of the dyes in their original forms. The same was observed using the electrolysis products obtained by oxidation and reduction conversions. The oxidation peak currents of the guanine and adenine moieties decreased when the concentrations of DO1 and DR1 were increased up to 5.0 × 10 -6 and 1.0 × 10-6 mol L-1, respectively; the signal decreases were more pronounced after interaction with the oxidized dyes, compared to the reduced compounds. The interactions between DNA and DO1, DR1, and the electrolyzed dyes were further investigated by UV-vis spectrophotometry in solution, and different effects such as hypochromism and hyperchromism were observed in the resulting DNA spectra. The investigated interactions showed clear evidence of changes in the DNA structure, and suggested a predominant intercalation mode leading to damage in the biomolecule. © 2013 Elsevier B.V.