Locust bean gum hydrogels are bioadhesive and improve indole-3-carbinol cutaneous permeation: influence of the polysaccharide concentration

Abstract The locust bean gum (LBG) is a polysaccharide with thickening, stabilizing and gelling properties and it has been used in the preparation of pharmaceutical formulations. Hydrogels (HGs) are obtained from natural or synthetic materials that present interesting properties for skin application. This study aimed to develop HGs from LBG using indole-3-carbinol (I3C) as an asset model for cutaneous application. HGs were prepared by dispersing LBG (2%, 3% and 4% w/v) directly in cold water. The formulations showed content close to 0.5 mg/g (HPLC) and pH ranging from 7.25 to 7.41 (potentiometry). The spreadability factor (parallel plate method) was inversely proportional to LBG concentration. The rheological evaluation (rotational viscometer) demonstrated a non-Newtonian pseudoplastic flow behavior (Ostwald De Weale model), which is interesting for cutaneous application. The HET-CAM evaluation showed the non-irritating characteristic of the formulations. The bioadhesive potential demonstrated bioadhesion in a concentration-dependent manner. Permeation in human skin using Franz cells showed that the highest LBG concentration improved the skin distribution profile with greater I3C amounts in the viable skin layers. The present study demonstrated the feasibility of preparing HGs with LBG and the formulation with the highest polymer concentration was the most promising to transport active ingredients through the skin.

Decreased Total Antioxidant Activity in Major Depressive Disorder Patients Non-Responsive to Antidepressant Treatment

OBJECTIVE: This study aimed to evaluate the total antioxidant activity (TAA) in patients with major depressive disorder (MDD) and the effect of antidepressants on TAA using a novel potentiometric method. METHODS: Twenty-eight patients with MDD and thirty-one healthy controls were enrolled in this study. The control group comprised 31 healthy individuals matched for gender, drinking and smoking status. We assessed symptoms of depression using the Hamilton Depression Rating Scale (HAMD) and the Beck Depression Inventory (BDI). We measured TAA using potentiometry. All measurements were made at baseline and four and eight weeks later. RESULTS: There was a significant negative correlation between BDI scores and TAA. TAA was significantly lower in the MDD group than in controls. When the MDD group was subdivided into those who showed clinical response to antidepressant therapy (response group) and those who did not (non-response group), only the non-response group showed lower TAA, while the response group showed no significant difference to controls at baseline. After eight weeks of antidepressant treatment, TAA in both the response and non-response groups was similar, and there was no significant difference among the three groups. CONCLUSION: These results suggest that the response to antidepressant treatment in MDD patients might be predicted by measuring TAA.

Determinação de fluoreto em baixas concentrações: validação de método com eletrodo íon seletivo para análise da água utilizada na preparação de soluções de diálise / Determination of fluoride at low concentrations: validation of method using ion selective electrode to analyze the water used in the preparation of dialysis solutions

Este trabalho descreve o desenvolvimento e validação de metodologia analítica para determinar a concentração de fluoreto em água empregada para a preparação de soluções de diálise, por meio de potenciometria com eletrodo íon seletivo. Os parâmetros de validação investigados foram: seletividade, homoscedasticidade, linearidade, limite de detecção, limite de quantificação, veracidade de medição e precisão. As condições otimizadas de análise foram: tampão HOAc/-OAc/NaCl/CDTA (pH = 5,0 ± 0,1), na proporção 10:1 (amostra/tampão); concentrações das soluções-padrão da curva analítica: 0,05 a 0,80 mg/L. O método avaliado exibiu parâmetros de validação adequados com limites de detecção e de quantificação, respectivamente, de 0,020 e 0,050 mg/L. Ademais, foi também desenvolvida e validada uma planilha eletrônica para efetuar o monitoramento da qualidade da curva analítica do método que calcula o limite de decisão para 0,20 mg/L...

Avaliação da liberação de íon fluoreto de cimentos ionoméricos antes e após a recarga e com proteção da superfície / Fluoride ion release from glass ionomer cements before and after recharge and surface protection

Objetivo: Avaliar a liberação de íon fluoreto de 2 cimentos de ionômerode vidro (CIV) anidro e 2 modificados por resina composta antes e apósrecarga com fluoreto de sódio neutro a 2% por 4min. e após a proteçãoda superfície do CIV Maxxion R com um adesivo odontológico, umverniz cavitário e um esmalte incolor para unhas.Métodos: Com uma matriz de aço inox com 2mm x 6mm,confeccionou-se 5 corpos de prova de cada material, que foramimersos em 5mL de água deionizada, trocada a cada 24h. Foramrealizadas leituras em um potenciômetro nos dias 1, 2, 9 e 17 na 1ª e 2ªetapas, e as amostras foram tamponadas com solução TISAB III. Na 2ªetapa, as amostras foram submetidas à recarga e novamente imersasem 5mL de água deionizada. Na 3ª etapa foi realizada a proteção dasuperfície dos CIVs e feitas leituras nos 5min., 24h, 48h e 72h. Utilizouseos testes estatísticos Post Hoc de Tukey e t Student (p<0,05).Resultados: Observou-se diferença estatisticamente significante aocomparar a 1ª com a 2ª etapas em todos os materiais, exceto no dia 2para o Vidrion R e para o VitroFil LC. Na 3ª etapa observou-se que emtodos os materiais, comparando os primeiros 5 min. com os outrostempos, as diferenças entre as médias da liberação das concentraçõesde íon fluoreto foram estatisticamente significantes. Ao 0comparar osdemais tempos, tanto o verniz quanto o esmalte incolor para unhasapresentou diferença estatisticamente significante entre 24h e 48h,bem como em 24h e 72h.Conclusão: Os CIVs anidros tiveram maior efetividade na liberação deíon fluoreto e na recarga em comparação com os CIVs modificados porresina composta e o Maxxion R apresentou um comportamentohomogêneo e estatisticamente significante nas duas etapas. Todos osmateriais protetores testados foram eficazes, e o esmalte incolor paraunhas apresentou o melhor comportamento...

Objective: To evaluate fluoride ion release from two anhydrous glassionomer cements (GICs) and two resin-modified GICs (RMGICs) before and after recharge with 2% neutral sodium fluoride for 4 min and after surface protection of the Maxxion R GIC with an adhesive system, a cavity varnish and a colorless nail polish. Method: A stainless steel 2x6 mm matrix was used for fabricating 5 specimens of each material, which were immersed in 5 mL of deionized water, renewed every 24 h. Measurements with a potentiometer were performed on days 1, 2, 9 and 17, in the 1st and 2nd phases, and thespecimens were buffered with a TISAB III solution. In the 2nd phase, thespecimens were subjected to recharge and immersed again in 5 mL ofdeionized water. In the 3rd phase, the GIC surfaces were protected andreadings were made at 5 min, 24 h, 48 h and 72 h. TukeyÆs post-hoc and StudentÆs t tests were used for statistical analyses (p<0.05). Results: There was statistically significant difference in the comparison between the 1st and 2nd phases for all materials, except at day 2 for Vidrion R and VitroFil LC. In the 3rd phase, it was observed that for all materials, comparison of the first 5 min with the other times revealedstatistically significant differences among the means of fluoride ionrelease. In the comparison with the other times, both the varnish and the colorless nail polish presented statistically significant differencebetween 24 and 48 h as well as between 24 and 72 h. Conclusion: The anhydrous GICs were more effective in fluoride ion release and recharge compared with the RMGICs. Maxxion R presented a homogeneous and statistically significant behavior in both phases. All materials for surface protection were efficient and the colorless nail polish had the best behavior...

Avaliação da acidez de diversas marcas de leite fermentado disponíveis comercialmente / Evaluation of the acidity of several fermented milk brands

Objetivo: O objetivo deste estudo foi a determinação do pH e da acidez titulável (capacidade de tampão) de diversas marcas de leite fermentado disponíveis comercialmente. Método: Foram analisadas sete marcas de leite fermentado: Yakult (Yakult®): sabor tradicional; Batavito (Batavo®): sabores tangerina, uva; Batavinho (Batavo®): sabores maçã e frutas cítricas; Bob esponja (Batavo®): sabores morango, frutas cítricas e uva; Danito (Danone®): sabor baunilha; Chamyto (Nestle®): sabor tradicional; Vig (Vigor®): sabor tradicional. A mensuração do pH inicial foi realizada com um potenciômetro e eletrodo combinado de vidro (Tec-2 Tecnal), sob temperatura própria para o produto. As embalagens foram agitadas manualmente por 15 segundos, coletando-se 2 amostras (15ml) de cada embalagem. Para a verificação da acidez titulável (capacidade tampão), foi coletado 50ml de cada embalagem, adicionando-se alíquotas de 100 µL de NaOH 1N, sob agitação constante (Agitador Magnético Fisaton), medindo-se subseqüentemente o pH, até elevar a valores imediatamente superiores a pH a 5,5. Resultados: Os resultados foram submetidos à análise estatística através do teste Scott-Knott (p< 0,05), onde todas as bebidas analisadas apresentaram valor de pH abaixo de 5,5 e variada capacidade tampão intrínseca. Conclusão: Todas as bebidas analisadas apresentaram valores de pH abaixo de 5,5. A presença de frutas na composição de algumas bebidas não influenciou na queda do pH, porém influenciou na capacidade tampão intrínseca. As bebidas com fruta na composição (Batavinho maçã e frutas cítricas (Batavo®)) juntamente com Yakult apresentaram a maior capacidade tampão intrínseca, e consequentemente o maior grau de acidez. A bebida Batavito uva (Batavo®) apresentou o menor grau de acidez. Desta forma, as bebidas analisadas podem contribuir para o potencial erosivo da dieta de crianças e adolescentes.

Purpose: The purpose is the determination of the pH and the titratable acidity (buffer capacity) of various brands of commercially available fermented milk. Method: Seven brands of fermented milk were analysed: Yakult (Yakult ®): traditional flavor; Batavito (Batavo ®): tangerine and grape flavors; Batavinho (Batavo ®): apple and citrus flavors; Bob esponja (Batavo ®): strawberry, citrus and grape flavors; Danito (Danone ®): vanilla flavor; Chamyto (Nestle ®): traditional flavor; Vig (Vigor ®): traditional flavor. The pH measurement was performed with a potentiometer and combined glass electrode (Tec-2 Tecnal), under appropriate temperature for the product. The packages were manually agitated for 15 seconds, then collected 2 samples (15 mg) of each package. Fifty (50) ml was collected from each package for the verification of titratable acidity (buffering), adding 100 µL aliquots of 1N NaOH, stirring constantly (Fisaton magnetic stirrer), and subsequently measuring the pH until rising it to values immediately above the pH of 5.5. Results: The results were submitted to a statistical analysis through the Scott-Knott test (p < 0.05), where all analyzed beverages showed pH below 5.5 and a varied intrinsic buffering capacity. Conclusion: All analyzed drinks showed pH values below 5.5. The presence of fruits in the composition of some beverages did not influence the pH decrease, however influenced in intrinsic buffering capacity. Beverages with fruits in their composition (Batavinho apple and citrus fruits (Batavo®)) and Yakult showed the highest intrinsic buffering capacity and consequently the higher degree of acidity. The The Batavito (Batavo®) grape drink presented the lowest degree of acidity. Thus, analyzed beverages may contribute to the erosive potential of child and adolescent diets.

Effects of chemical composition on the corrosion of dental alloys

The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.

O objetivo deste estudo foi determinar o efeito do ambiente bucal na corrosão de diferentes ligas odontológicas, utilizando métodos eletroquímicos. Os índices de corrosão foram obtidos por meio das curvas de corrente-potencial e impedância eletroquímica (EIS). O efeito de saliva artificial na corrosão de ligas odontológicas foi dependente da composição. A dissolução dos íons ocorreu em todas as amostras e os resultados foram dependentes da composição da liga. Algumas mudanças na microestrutura foram observadas durante o estudo e influenciou o comportamento corrosivo das ligas investigadas. As ligas de Ni-Cr e Ni-Cr-Ti libertaram quantidade de 0,62 mg/L de íons Ni enquanto a liga de Co-Cr liberou entre 0,01 e 0,03 mg/L. As curvas potenciodinâmicas das ligas odontológicas mostraram que as ligas a base >70 wt% de Ni obtiveram curvas similares e a liga de Co-Cr apresentou a menor densidade de corrente e em consequência uma resistência alta a corrosão quando comparada as ligas à base de Ni. A baixa resistência à corrosão também levou a maior libertação de íons de níquel para o meio e a quantidade de Co liberado pela liga de Co-Cr-Mo foi relativamente pequena nas soluções. As quantidades de Cr liberada na saliva artificial pela liga de Co-Cr foi menor que a libertação de Cr pela liga à base de Ni.

Determination methods for the content of methyl salicylate-2-O-beta-D-galactopyranoside (1-4)-beta-D-glucopyranoside / 药学学报

The paper is to report the establishment of three methods for determination of methyl salicylate-2-O-beta-D-galactopyranoside (1-4)-beta-D-glucopyranoside (MSG) by HPLC, UV or potentiometric titration. The results determined by the three methods turned out to be of no significant difference (P>0.05). The method was chosen according to MSG difference test demands.

Diabetic ketoacidosis: difference between potassium determined by blood gas analysis versus plasma measurement / Cetoacidose diabética: diferença entre as concentrações do potássio na gasometria sanguínea versus potássio plasmático

OBJECTIVE: To evaluate the accuracy of potassium concentrations measured by blood gas analysis (PBG) compared with laboratory serum potassium (LSP), in the initial care of patients with diabetic ketoacidosis (DKA). SUBJECTS AND METHODS: Fifty three patients with diabetes mellitus were evaluated in a retrospective analysis. PBG was carried out using the Radiometer ABL 700 (Radiometer Copenhagen®), and results were compared with LSP ADVIA 1650 Chemistry system (Siemens®), the gold standard method. Both methods are based on potentiometry. RESULTS: Mean PBG was 3.66 mmol/L and mean LSP was 4.79 mmol/L. Mean difference between PBG and LSP was -1.13 mmol/L (p < 0.0005, 95 percent CI, -1.39 to -0,86). Lin concordance correlation coefficient was rc = 0.28 (95 percent CIb, 0.10 to 0.45), demonstrating low concordance between the methods. CONCLUSION: Although PBG measurement is faster and easier, it should not be used as a surrogate for LSP in the clinical treatment of DKA.

OBJETIVO: Avaliar a acurácia da mensuração da concentração de potássio realizado nos analisa-dores de gasometria sanguínea (PGS) em relação ao potássio plasmático laboratorial (PPL) no atendimento inicial dos pacientes com cetoacidose diabética (CAD). SUJEITOS E MÉTODOS: Foram avaliados, retrospectivamente, 53 pacientes com diabetes melito e CAD. A análise do PGS foi realizada pelo equipamento ABL 700 (Radiometer Copenhagen®), sendo este comparado ao método padrão-ouro de PPL ADVIA 1650 (Siemens®), ambos por potenciometria. RESULTADOS: A média do PGS foi de 3,66 mmol/L e do PPL, de 4,79 mmol/L. A diferença das médias do PGS em relação ao PPL foi de -1,13 mmol/L (p < 0,0005, IC = 95 por cento; -1,39 a -0,86). O coeficiente de concordância de Lin foi de rc = 0,28 (ICb = 95 por cento; 0,10 a 0,45), demonstrando, assim, uma baixa concordância entre os métodos. CONCLUSÃO: Apesar de a realização do PGS ser tecnicamente mais rápida e fácil, não deve ser usada como parâmetro substituto ao PPL para o tratamento clínico da CAD.

Análise da concentração de flúor na água em Curitiba, Brasil: comparação entre técnicas / Analysis of water fluoride concentration in Curitiba, Brazil: comparison of techniques

OBJETIVO: Avaliar a adequação dos níveis de fluoreto nas águas de abastecimento público em Curitiba, Estado do Paraná, Brasil, de acordo com duas técnicas (SPADNS e eletrométrica). MÉTODOS: Foram levantados os dados do heterocontrole na Cidade de Curitiba de janeiro de 2000 a julho de 2008 no banco de dados da Secretaria Municipal da Saúde para cálculo das médias anuais. Na sequência, foram comparadas as concentrações de fluoreto fornecidas pela companhia de saneamento SANEPAR (técnica eletrométrica) com as concentrações obtidas pelo heterocontrole (SPADNS) em 1 470 amostras de água coletadas e analisadas entre 2006 e 2007. Foi calculada a proporção de amostras dentro do padrão ideal de fluoretação para a Cidade (0,8 ppmF), abaixo do ideal e acima do ideal para ambas as metodologias. Foram exploradas diferenças na fluoretação entre distritos sanitários, meses do período dezembro de 2007 a julho de 2008 e estações de tratamento de água (ETA). RESULTADOS: A média geral de flúor entre 2000 a 2008 foi de 0,7 ppmF conforme os dados do heterocontrole. A comparação das técnicas eletrométrica e SPADNS revelou que o valor médio de fluoreto na água é maior quando avaliado pela técnica eletrométrica (0,743 ppmF ± 0,133) quando comparado com a técnica SPADNS (0,637 ppmF ± 0,164). A proporção de amostras dentro do padrão ideal de fluoretação foi de 15,05 por cento para SPADNS e 63,97 por cento para eletrométrica; de 62,03 e 22,85 por cento para amostras abaixo do ideal; e de 21,10 e 13,18 por cento para amostras acima do ideal, respectivamente. Houve diferença estatisticamente significativa na fluoretação entre os distritos sanitários (P < 0,001) e os meses pesquisados. CONCLUSÕES: A escolha da técnica analítica interfere significativamente no processo do heterocontrole. O heterocontrole deve utilizar a mesma técnica de determinação de flúor utilizada pela empresa de tratamento de água. Novos estudos devem definir qual técnica é a mais adequada para medir o teor de flúor.

OBJECTIVE: To evaluate the adequacy of fluoride levels in the public water system in Curitiba, state of Paraná, Brazil, as determined by two techniques (colorimetric and electrometric). METHODS: Data from independent measurements of fluoride in the public water system in Curitiba routinely performed by the city government were obtained for the period between January 2000 and July 2008. Mean levels of fluoride concentration were calculated for each of these years. After that, fluoride concentrations measured in 1 470 samples by the state water utility (SANEPAR) using the electrometric technique in 2006 and 2007 were compared with the corresponding levels measured by the city using the colorimetric method. The rate of samples meeting the standard for the city (0.8 ppmF), and below and above the standard, was calculated for both methods. Fluoride levels were compared between sanitary districts, months for the period between December 2007 and July 2008, and water treatment facilities. RESULTS: The overall mean fluoride level between 2000 and 2008 was 0.7 ppmF based on the independent measurements. The comparison between techniques showed a higher mean fluoride level with the electrometric technique (0.743 ppmF ± 0.133) vs. the colorimetric technique (0.637 ppmF ± 0.164). The rate of samples meeting the ideal standard of 0.8 ppmF was 15.05 percent for the colorimetric and 63.97 percent for the electrometric technique; 62.03 percent and 22.85 percent of the samples were below that standard and 21.10 percent and 13.18 percent were above that standard, respectively. Fluoride levels were statistically significant (P < 0.001) for the comparison between sanitary districts and months. CONCLUSIONS: The choice of technique significantly influences the resulting levels of fluoride. Independent monitoring of fluoride levels should employ the same technique used by the water utility. Further studies should aim at defining which technique is the most adequate to determine fluoride concentration in public water systems.

Fluoride Release from Restorative Materials

The aim of this study was to evaluate in vitro fluoride (F) release from 4 restorative materials (3M ESPE): Ketak Molar Easymix [KME - conventional glass ionomer cement (GIC)]; Rely-X luting 2 [RL2 - resin-modified GIC (RMGIC)]; Vitremer (VIT- RMGIC); and Filtek Z250 [Z250 - negative control]. Disc-shaped specimens were fabricated according to the manufacturer’s instructions and placed into 10 mL of reverse osmosis water at 37°C until the analyses were done using a liquid membrane for selective F ion electrode (Orion 710). F release was evaluated every 6 h in the first day and thereafter daily during 28 days (d). The results were analyzed statistically by two-way ANOVA and Tukey’s test (α=0.05). Mean F release and standard deviation values (in ppm) were: KME: 6 h- 0.34 ± 0.04; 24 h- 1.22 ± 0.30; 7 d- 0.29 ± 0.09; 14 d- 0.20 ± 0.04; 28 d- 0.16 ± 0.01; RL2: 6 h- 2.46 ± 0.48; 24 h-12.33 ± 2.93; 7 d- 1.37 ± 0.38; 14 d- 0.80 ± 0.13; 28 d- 0.80 ± 0.21; VIT: 6 h- 0.98 ± 0.35; 24 h- 4.35 ± 1.22; 7 d- 0.66 ± 0.23; 14 d- 0.40 ± 0.07; 28 d- 0.39 ± 0.08; Z250: 6 h- 0.029 ± 0.001; 24 h- 0.024 ± 0.009; 7 d- 0.023 ± 0.004; 14 d- 0.025 ± 0.001; 28 d- 0.028 ± 0.001. RL2 RMGIC released more F than the other materials in all periods. The greatest release of F occurred in the first 24 h.

O objetivo deste estudo foi avaliar, in vitro, a liberação de flúor (F) de 4 materiais restauradores (3M-ESPE): KME cimento de ionômero de vidro convencional (CIV) (Ketak Molar Easymix); RX2- GIC modificado por resina (RMGIC) (Rely-X luting 2); VIT-RMGIC (Vitremer); -resina composta Z250 (controle negativo) (Filtek Z250). As amostras foram confeccionadas de acordo com as instruções do fabricante e colocadas em 10 mL de água destilada 37°C até as leituras, que foram feitas utilizando um eletrodo de íon seletivo de fluoreto de membrana líquida (Orion 710). A liberação de flúor foi avaliada a cada 6 h no primeiro dia e, diariamente durante 28 dias (d). Os resultados foram analisados estatisticamente usando ANOVA a dois critérios e teste de Tukey. A média e desvio padrão de liberação de F, valores (em ppm) foram: KME: 6 h- 0,34 ± 0,04; 24 h- 1,22 ± 0,30; 7 d- 0,29 ± 0,09; 14 d- 0,20 ± 0,04; 28 d- 0,16 ± 0,01; RL2: 6 h- 2,46 ± 0,48; 24 h- 12,33 ± 2,93; 7 d- 1,37 ± 0,38; 14 d- 0,80 ± 0,13; 28 d- 0,80 ± 0,21; VIT: 6 h- 0,98 ± 0,35; 24 h- 4,35 ± 1,22; 7 d- 0,66 ± 0,23; 14 d- 0,40 ± 0,07; 28 d- 0,39 ± 0,08; Z250: 6 h- 0,029 ± 0,001; 24 h- 0,024 ± 0,009; 7 d- 0,023 ± 0,004; 14 d- 0,025 ± 0,001; 28 d- 0,028 ± 0,001. Concluiu-se que RL2 liberou mais F do que os outros materiais em todos os períodos. A maior liberação de F ocorreu nas primeiras 24 h.

Synthesis, spectroscopic and potentiometric studies on a silver [I] complex derived from a new BIS [thiosemicarbazone]

A new reagent, [2E, 2Z]2,2-[3[E]-[2-hydroxyphenyl] diazenyl] pentane-2,4-diylidene] bis [hydrazinecarbothioamide] [OPTS] was synthesized and studied. Acid-base, spectrophotometric properties of OPTS were studied in 50% ethanol-water mixture solutions at pH 3-11. Ionization constants of the reagent OPTS have been determined by a spectrophotometric and potentiometric titrations: pK[1]=9.60 +/- 0.02; pK[2]= 10.45 +/- 0.05 in its computational and graphical versions at an ionic strength 0.1 M Na10[4]. The stability constants of the Ag-OPTS are logK[1]=4.55 +/- 0.04 and 10gK[2]=3.92 +/- 0.05. The reaction of Ag [I] with OPTS gives a mononuclear complex in 50% ethanol water mixture solution with lambda[max]=462 nm at pH=8.1. The effects of foreign ions and masking agents on the determination of Ag [I] with the new reagent are studied. The mono complex obeys the Beer's law in the Ag [I] concentration range 1.1-17 mg/25ml. Molar absorption coefficients were determined. In this paper, we report the synthesis of the novel Ag [l] complexes with OPTS. The complexes were characterized by UV-Vis and IR spectroscopy, elemental analysis, molar conductivity and thermal decomposition

Spectrophotometric and potentiometric methods for the determination of cefprozil, dropropizine and tizanidine hydrochloride in pharmaceutical preparations

Two simple, accurate spectrophotometric and potentiometric methods were developed for the determination of cefprozil, dropropizine and tizanidine hydrochloride in their pharmaceutical preparations. The spectrophotometric method is based on the selective oxidation of cefprozil or tizanidine with N-bromosuccinimide in an alkaline medium to given an intense yellow product with a maximum absorption at 396 or 384 nm, respectively. The reaction conditions were studied and optimized. The reaction obeyed Beer's law over the concentration range 5-40 and 10-80 micro g mI[-1] for cefprozil and tizanidine hydrochloride, respectively. The potentiometric method involves the direct titration of cefprozil and dropropizine with N-bromosuccinimide in sulphuric acid medium and the end point is determined potentiometrically using platinum electrode. Cefprozil and dropropizine can be determined quantitatively in the concentration range of 0.13-1.30 and 0.118-1.180 mg with recovery values of 98.46-100.77 and 99.58-100.85% and relative standard deviations 0.39-0.54 and 0.52-0.87% for cefprozil and dropropizine, respectively. The proposed methods are applied for the determination of these drugs in pure forms and in pharmaceutical preparations

The electrochemical properties of four dental casting suprastructure alloys coupled with titanium implants

OBJECTIVES: As the choice of suprastructure alloy to be combined with titanium for the oral cavity is still a much debated issue, the aim of this study was to investigate the electrochemical interaction of the suprastructure/implant couples under the determined experiment conditions. MATERIAL AND METHODS: The potentiodynamic polarization curves and open-circuit potentials (OCP) of four UCLA type suprastructures coupled with straight Swiss Plus implant fixtures were taken in Afnor type artificial saliva solution at 37°C. The concentration of ions leached into artificial saliva solutions was estimated with ICP-MS. SEM images of the margins of suprastructure/implant couples were obtained before and after the electrochemical tests. RESULTS: The OCP value of titanium became passive at the most negative potential. The lowest difference between the initial and constant OCP value was exhibited by the Au based suprastructure. Suprastructures made greater contributions to the potentiodynamic polarization curves of the implant/suprastructure couples. According to the ICP-MS results, Pd based and Au based couples dissolved less than Co-Ni based and Co-Cr based couples. CONCLUSIONS: Within the conditions this study, it may be concluded that the titanium implant forms a stable passive oxide layer in artificial saliva exposed to open air and does not affect the corrosion properties of the suprastructures. Pd based and Au based couples have been found to be more corrosion-resistant than base alloy couples.

[Comparison of enamel fluoride uptake between three different glass ionomers used in orthodontic banding: an in vitro study]

Decalcification of the teeth remains a problem during orthodontic treatment with fixed appliances. It has been suggested that fluoride-releasing glass ionomer cements could decrease the risk of enamel decalcification under orthodontic bands. The objective of this study was to compare enamel fluoride uptake from three different glass ionomer cements [Aqua Cem, Resilience and Bandite] used for band cementation in permanent teeth in vitro. In an experimental in vitro randomized trial, 33 sound premolars that were extracted for orthodontic purposes were randomly divided into thee groups. In each group one of the glass ionomer cements was tested. A 6 mm diameter adhesive tape was placed over the center of buccal enamel surface of each tooth and then the entire surfaces of them were painted with two layers of an acid protective nail polish. After removing adhesive tapes, brackets were cemented with one of the cements over the window. Then all the specimens were immersed in 5ml deionized water for one month. Brackets were debonded and remnants of cements were removed. The windows were etched with 1mI perchloric acid 0.5 M for 60 seconds and then 4 ml of 0.5 M Total Ionic Strength Adjustment Buffer [TISAB] was added to perchloric acid. Fluoride and calcium concentration of the solutions were determined by Potentiometer and Inductively Coupled Plasma, respectively. The depth of etch and fluoride concentration in the enamel were calculated, and the results were analyzed with one way ANOVA and Kruskal-Wallis test. In Resilience the mean fluoride concentrations group were higher and depths of etch were lower than in the other two groups. But there was no statistically significant difference between them. It seemed that an increase in fluoride uptake may be capable of rendering a tooth more resistant to dental decalcification

Thermodynamic study on the complexation of dioxovanadium [V] with isoleucine and glycylglycine

The dissociation constants of isoleucine and glycylglycine have been determined using a suitable computer program which employs a nonlinear least squares method. The complexation of dioxovanadium [V] with glycylglycine was studied by a combination of potentiometric and spectrophotometric techniques in aqueous solution at 25 °C and 0.1 mol dm[-3] ionic strength [NaClO[-4] in the pH range 2.00 to 2.60. All of the calculations have been done by the computer program Excel 2000. Dioxovanadium [V] complexes formed by isoleucine in the pH range 1.30 to 2.5 and between t = 25 °C and 35 °C with one mole dm[-3] sodium perchlorate as the ionic medium, have been investigated potentiometrically and spectrophotometrically. Ultimately, the thermodynamic functions [delta G°, delta H°, delta S°] have been calculated for the complexation of dioxovanadium [V] with isoleucine

[Fluoride content of drinking waters in Kerman/Iran]

It has been proved that sufficient amount of fluoride in drinking water can decrease the rate of dental caries. The aim of this study was to determine fluoride content of drinking waters in the 8 cities of Kerman province as well as 11 types of mineral water sold in supermarkets of Kerman. Fluoride contents of 42 drinking water samples belonged to 8 cities of Kerman province and 11 brands of mineral water sold in Kerman city was determined by ponentiometry method and using specific electrode of fluoride ion. Mean Fluoride content of drinking water was 0.17 ppm in Kerman, 0.47ppm in Zarand, 0.39ppm in Rafsanjan, 0.49ppm in Jiroft, 0.43 ppm in Bam, 0.39ppm in Sirjan, 0.44ppm in Kahnooj and 0.41ppm in Baft. Fluoride content of studied mineral waters was in the range of 0.04 - 0.27ppm. Considering the temperature of these cities, it seems that the fluoride content of drinking waters is lower than the recommended range for preventing dental caries

[Comparing the spectrophotometric and potentiometric methods in determining the concentration of fluoride in water]

According to the importance of fluoride in water based on "DMFT" and 2 other reports which indicates that Spectrophotometeric method for measurement the fluoride water can not show the real amount of flouride, Potentiometer seems to be better than Spectrophotometer. To compare these two methods for measuring the amount of flouride, this research carried out in organic chemistry laboratory of Tehran University between 2006 and 2007. In this descriptive study, after obtaining the distilled water, they were prepared in 7 groups with 0, 0.35, 0.67, 0.7, 1, 1.2, 1.5 ppm of fluoride in 14 polyethylene containers and 2 samples were prepared from each type. In following, half of them were measuerd by standard spectrophotometer method [with the use of visible instrument in the same wave length, amount of light coefficient with standard solutions]. Using standard solutions of 10[-1] M up to 10[-5] M fluoride in the other half of samples, the calibration curve according to the findings was drawn. By studying the potentiometer amounts of samples and compare them with calibration curve, sample density were found. At the end, findings were changed to ppm. Therefore, the amount of fluoride in water were determined and the difference to the real fluoride in samples in each method were indicated. This difference in each method was calculated by paired-t test, whereas Mann-Whitney U test evaluated two groups with each other. The research studied 14 water samples with real fluoride of 0.77 +/- 0/58. In spectrophotometer method the fluoride amount was 0.99 +/- 0/58 with the difference of 0/82 +/- 0.23 from real amount [P<0.5]. In potentiometer this amount was 0.77 +/- 0/52 with the difference of 0.02 +/- 0.01. [P<0.4]. Amount of fluoride in spectrophotometer is 19.5% higher than potentiometer. Potentiometer method is better than spectrophotometer for indicating the fluoride in water and this method is, therefore, recommended

Comparative Determination of Chlorpromazine Hydrochloride Content in Multi-sourced Chlorpromazine Tablets in Nigeria

Purpose: Although different brands or unbranded chlorpromazine tablets from multiple sources are available in Nigeria today; they must all contain the same active principle and satisfy the standards of quality; efficacy and safety. This study is designed to check for possible faking and adulteration of chlorpromazine tablets and also establish the possibility of inter-brand substitution based on drug content (chemical equivalence). Method: The determination of the chlorpromazine hydrochloride content was carried using non-aqueous titrimetric and spectrophotometric methods. Glacial acetic acid and acetone were used as the non-aqueous solvent and equivalence points were determined using visual indicators and potentiometer. Results: The results obtained showed that all the brands analyzed met the specification of the British Pharmacopoeia and so contain acceptable amounts of chlorpromazine drug content thus enabling possible brand substitution. Statistical comparison showed no significant difference between the results obtained by determining end-point using visual indicators and the potentiometer. Conclusion: The use of the visual indicator method is recommended for fast and accurate routine laboratory analytical work especially in developing nations

Correlación y conversión entre los valores de actividad de la colinesterasa plasmática medida por tres técnicas diferentes / Correlation and conversion of plasma cholinesterase activity values using three techniques

OBJETIVO: Determinar las relaciones matemáticas entre tres técnicas cuantitativas empleadas para medir la actividad de la colinesterasa plasmática, a partir de los valores de referencia ya establecidos para dos poblaciones de Antioquia, Colombia. MÉTODOS:Diseño descriptivo, transversal y prospectivo. Se conformaron dos muestras independientes representativas de la población laboral adulta (18-65 años), no expuesta a plaguicidas inhibidores de la colinesterasa y vinculada al Seguro Social, del valle de Aburrá (415 personas) y del cercano oriente antioqueño (412 personas), del departamento de Antioquia, Colombia. La colinesterasa plasmática (EC 3.1.1.8) se midió mediante tres técnicas cuantitativas: Michel, EQM® y Monotest®. Se elaboraron ecuaciones de regresión que relacionaran entre sí los resultados de las tres técnicas estudiadas. RESULTADOS: Se definieron seis ecuaciones de regresión lineal simple que permitieron relacionar los resultados de las tres técnicas de medición de colinesterasa plasmática analizadas. La correlación entre las técnicas fue moderada (r: de 0,686 a 0,771), pero aumentó (r: de 0,744 a 0,811) al eliminar 12 (1,5 por ciento) valores extremos. Las asociaciones entre las técnicas fueron altamente significativas (P < 0,001). Las ecuaciones Y = a + bX ajustadas son: EQM (U/mL) = 0,40773 + 1,8757 (Michel [delta pH/hora]); Michel (delta pH/hora) = 0,25799 + 0,33871 (EQM [U/mL]); Monotest (U/L) = 462,0 + 4 565,0 (Michel [delta pH/hora]); Michel (delta pH/hora) = 0,42956 + 0,00012125 (Monotest [U/L]); EQM (U/mL) = 0,75333 + 0,00031056 (Monotest [U/L]); y Monotest (U/L) = 262,0 + 2 118,0 (EQM [U/mL]). CONCLUSIONES: Los modelos propuestos permiten convertir los valores de actividad de la colinesterasa medida con las tres técnicas estudiadas.

OBJECTIVES: To determine mathematical correlations of three quantitative techniques to measure plasma cholinesterase, using reference values already established for two populations in the department of Antioquia, Colombia. METHODS: In this descriptive, cross-sectional, prospective study, two independent, representative samples of working adults (18 to 65 years old) were examined. In both samples the adults worked for businesses associated with ColombiaÆs Social Security system. Adults in the two samples had not been exposed to cholinesterase-inhibiting pesticides. The samples were from two neighboring regions of the department of Antioquia: one sample (415 adults) was from the Aburrá Valley, and the other (412 adults) was from Oriente Antioqueño (Eastern Antioquia). Plasma cholinesterase (EC 3.1.1.8) was measured using three quantitative methods: Michel, EQM, and Monotest. Linear regression equations were developed to correlate results of these three techniques. RESULTS: Six simple linear regression equations were defined to show the relationship of three measurement techniques for plasma cholinesterase. There was a moderate correlation of the three techniques (r = 0.686 to 0.771), but it increased (r = 0.744 to 0.811) when 12 (1.5 percent) outliers were eliminated. Associations among the three techniques were highly significant (P < 0.001). The adjusted equations for Y = a + bX are: EQM (U/mL) = 0.40773 + 1.8757 (Michel [delta pH/h]); Michel (delta pH/h) = 0.25799 + 0.33871 (EQM [U/mL]); Monotest (U/L) = 462.0 + 4 565.0 (Michel [delta pH/h]); Michel (delta pH/h) = 0.42956 + 0.00012125 (Monotest [U/L]); EQM (U/mL) = 0.75333 + 0.00031056 (Monotest [U/L]); and Monotest (U/L) = 262.0 + 2 118.0 (EQM [U/mL]). CONCLUSIONS: The proposed mathematical models allow conversion of cholinesterase activity values using the Michel, EQM, and Monotest techniques. These models can be of assistance in Colombia and other countries where a variety of measurement...

Desenvolvimento e validação de metodologia analítica para a determinação do teor de ácido glicólico na matéria-prima e em formulações dermocosméticas / Development and validation of an analytical methodology for determination of glycolic acid acid in raw material and dermocosmetic formulations

O ácido glicólico é amplamente utilizado na terapêutica para se obter um peeling suave, levando ao afinamento do estrato córneo útil na renovação da epiderme e na redução das linhas faciais. Porém, em concentrações elevadas pode estar associado a um alto potencial de irritação da pele. O peeling químico tem diversas aplicações clínicas dentre elas o tratamento da pele facial lesada por problemas como acne, ictiose, melasma, verrugas e outros problemas. O presente trabalho objetivou estabelecer e validar a metodologia analítica para a determinação do teor de ácido glicólico na matéria-prima e em formulações dermocosméticas, tendo empregado o método titulométrico de neutralização ácido-base, determinando-se o ponto de equivalência com indicador e/ou indicação potenciométrica. A análise do teor de ácido glicólico na matéria-prima e, particularmente, no produto acabado, é importante para o controle de qualidade, principalmente, para a segurança dos consumidores. Portanto, a matéria-prima e os produtos, contendo ácido glicólico, foram analisados em dois dias, quanto ao teor de ácido glicólico livre e total utilizando soluções de hidróxido de sódio 0,1 N e o ácido clorídrico 0,1 N. A metodologia desenvolvida baseou-se na reação com a substância ativa e com as características próprias destas formulações, demonstrando ser prática e eficaz na quantificação do ácido glicólico.

Glycolic acid is widely used in therapeutical care as a soft peeling, leading to the thickness of the horny layer, which is useful in the renewal of the epidermis and the reduction of the face lines. However, in high concentrations it can be associated to a potential of irritation of the skin. A chemical peeling has diverse clinical applications, among them the treatment of injured skin face like: acne, ichthyose, melasma, warts and other else. The present work had the goal to establish and to validate an analytical methodology for the determination of the glycolic acid purity in the raw material and in the dermocosmetic formulations, the acid-base neutralization titration method was used, and the end point was determined with visual indicator as well as potenciometric. The analysis of glycolic acid in the raw material, and particularly, in the finished product is important to maintain the quality control and to guarantee the consumers security. Therefore, the raw material and the products, with glycolic acid, were analyzed in two days, as its purity in free and total glycolic acid was determined using sodium hydroxide 0,1 N and the hydrochloric acid 0,1 N solutions. The developed methodology was based on the reaction with the active substance and with the property characteristics of these formulations. It was demonstrated to be practical and efficient in quantify the glycolic acid.