Effect of Composite Containing an Iodonium Salt on the Bond Strength of Brackets to Bovine Enamel

This study investigated the effect of the incorporation of an iodonium salt in experimental composites, on the bond strength of metallic brackets bonded to bovine teeth. Two hundred and seventy bovine teeth were embedded in self-curing acrylic resin and divided into 18 groups (n=15), according to the experimental composite with an iodonium salt at molar concentrations 0 (control), 0.5, or 1%; the light-activation times (8, 20 and 40 s); and the storage times (10 min or 24 h). Metallic brackets were fixed on the tooth surface using experimental composites. Photoactivation was performed with a quartz-tungsten-halogen light-curing unit curing unit for 8, 20 and 40 s. The specimens were stored in distilled water at 37 °C for 10 min or 24 h and submitted to bond strength test at 0.5 mm/min. The data were subjected to three-way ANOVA and Tukey's test (α=0.05). The Adhesive Remnant Index (ARI) was used to classify the failure modes. The shear bond strengths (MPa) at 10 min for light-activation times of 8, 20 and 40 s were: G1 - 4.6, 6.9 and 7.1; G2 - 8.1, 9.2 and 9.9; G3 - 9.1, 10.4 and 10.7; and at 24 h were: G1 - 10.9, 11.1 and 11.7; G2 - 11.8, 12.7 and 14.2; G3 - 12.1, 14.4 and 15.8. There was a predominance of ARI score 3 for groups with 10 min storage time, and ARI score 2 for groups with 24 h storage time. In conclusion, the addition of iodonium salt (C05 and C1) to the experimental composite may increase the bond strength of brackets to bovine enamel using reduced light exposure times.

Estudo investigou o efeito da incorporação de um sal de iodônio em compósito experimental, na resistência de união de braquetes metálicos fixados em dentes bovinos. Duzentos e setenta dentes bovinos foram embutidos e divididos em 18 grupos (n=15), de acordo com o compósito experimental com sal de iodônio na concentração molar de 0 (controle), 0,5 e 1 %; tempo de fotoativação (8, 20 e 40 s); e, tempo de armazenagem (10 min e 24 h). Braquetes metálicos foram fixados na superfície do dente usando compósitos experimentais. A fotoativação foi efetuada com o aparelho XL 2500 por 8, 20 e 40 s. As amostras foram armazenadas em água destilada a 37º C por 10 min e 24 h e submetidos ao ensaio de resistência de união à velocidade de 0,5 mm/min. Os dados foram submetidos à Análise de variância de 3 fatores e ao teste de Tukey (α=0,05). O Índice de Remanescente do Adesivo (IRA) foi usado para classificar os modos de falhas. Os valores de resistência de união ao cisalhamento (MPa) no período de 10 min para os tempos de fotoativação de 8, 20 e 40 s foram: G1 - 4,6; 6,9 e 7,1; G2 - 8,1; 9,2 e 9,9; G3 - 9,1; 10,4 e 10,7; e no período de 24 h foram: G1 - 10,9; 11,1 e 11,7; G2 - 11,8; 12,7 e 14,2; G3 - 12,1; 14,4 e 15,8. Houve predominância de escore 3 para os grupos armazenados por 10 min e escore 2 para os grupos armazenados por 24 h. Em conclusão, a adição do sal de iondônio (C05 e C1) em compósitos experimentais pode aumentar a resistência de união de braquetes ao esmalte bovino usando reduzidos tempos de fotoativação.

In vitro susceptibility of Staphylococcus aureus strains isolated from cows with subclinical mastitis to different antimicrobial agents

Sensitivity to commercial teat dips (nonoxinol-9 iodine complex and chlorhexidine digluconate) of 56 Staphylococcus (S.) aureus strains isolated from quarter milk samples of various German dairy herds treated with different teat dipping schemes was investigated in this study. The minimum inhibitory concentration was determined using a broth macrodilution method according to the German Veterinary Association guidelines. The main objective of the current study was to induce in vitro resistance induction of S. aureus to chemical disinfectants. Ten different strains were repeatedly passed ten times in growth media with sub-lethal concentrations of disinfectants. Nine strains showed a significant reduction in susceptibility to the nonoxinol-9 iodine complex but only one strain developed resistance to chlorhexidine digluconate. Stability of the acquired resistance was observed in all S. aureus strains adapted to the nonoxinol-9 iodine complex and chlorhexidine digluconate. In contrast, simultaneous resistance to different antibiotics was not observed in any of the ten investigated S. aureus strains. However, the isolates exhibited a high degree of resistance to penicillin G. Based on these results, resistance of S. aureus to chemical disinfectants may be more likely to develop if the chemicals are used at concentrations lower than that required for an optimal biocidal effect.

New iodine derivatives of flavonol and isoflavone

The reaction of the flavonol 3,7,3', 4'-tetra-O-methylquercetin (1) and of the isoflavone 7,4'-di-O-methylgenistein (2) with alkaline iodine in methanol afforded four new iodine derivatives: 8-iodo-5-hydroxy-3,7,3', 4'-tetramethoxy- flavone (1a) and 6-iodo-5-hydroxy-3,7,3', 4'-tetramethoxyflavone (1b) from 1; 2 afforded a mixture of two compounds, identified as a racemic mixture of (±)-trans-5-hydroxy-2,3,7,4'-tetramethoxy-8-iodo-isoflavanone (2a) and (±)-trans-5-hydroxy-2,3,7,4'-tetramethoxy-6,8-diiodo-isoflavanone (2b). The formation of these different products reveals a significant difference involving the chemical interaction between the reactive site of α, β-unsaturated ketones of flavonol and isoflavone under the tested reaction conditions (using I2/KOH/MeOH). Furthermore, the trans stereo selectivity is noteworthy in the nucleophylic addition of methanol at the isoflavone α, β-unsaturated system. The structures were identified on the basis of spectral data, mainly 1D and 2D NMR and mass spectra.

A reação do flavonol 3,7,3',4'-tetra-O-metilquercetina (1) e da isoflavona 7,4'-di-O-metilgenisteina (2) com iodo/KOH em metanol forneceu como produto quatro derivados iodados: 8-iodo-5-hidroxi-3,7,3',4'-tetrametoxiflavona (1a) e 6-iodo-5-hidroxi-3,7,3',4'-tetrametoxiflavona (1b) a partir da iodação de 1; a partir de 2 foi obtida uma mistura racêmica composta de (±)-trans-5-hidroxi-2,3,7,4'-tetrametoxi-8-iodo-isoflavanona (2a) e (±)-trans-5-hidroxi-2,3,7,4'-tetrametoxi-6,8-diiodo-isoflavanona (2b). A formação destes diferentes produtos revela a significante diferença envolvendo a interação química entre o sitio reativo de cetonas α, β-insaturadas de flavonol e de isoflavonas nas condições experimentais testadas (usando I2/KOH/MeOH). Além disso, ressalta-se a estereosseletividade trans na adição de metanol ao sistema α, β-insaturado da isoflavona. As estruturas foram identificadas com análise nos dados espectrométricos de RMN 1D e 2D e massas.

[Comparison of urine and milk iodine concentration among congenitally hypothyroid neonates and their mothers and a control group]

Although Iran is known as an iodine sufficient area, congenital hypothyroidism [CH] is prevalent. Because iodine excess can contribute to hypothyroidism we evaluated the role of iodine excess and ID in the etiology of CH. In a cross sectional study UICs [Urine Iodine Concentration] in newborns with CH as well as UIC and MIC [Milk Iodine Concentration] of their mothers were compared with a control group. After acid digestion of urine samples milk samples, iodine concentrations were determined by the Sandell-Kolthoff method. Chi-square and Wilcoxon, and Pearson correlation tests were used for statistical analysis. A P value less than 0.05 was considered statistically significant. The median of MIC of CH [n=68] and healthy subjects [n=179] was different [210 vs. 170 micro g/L respectively, P<0.05]. However the median of UIC in neonates and those of mother's of CH and healthy subjects were not different statistically [305 vs. 300 micro g/L and 150 vs. 130 micro g/L respectively, P>0.05]; 71.2% and 46.7% of mothers of hypothyroid and healthy subjects had MICs above 180 micro g/I [iodine excess] respectively [p=0.002]. Based on the higher levels of MIC in mothers of CH neonates, iodine excess could be a possible risk factor for CH. Since however comparison of UIC between the control and neonate groups showed no differences, further investigations are needed to facilitate deeper insight into and clarification of the etiology of CH

Chronic maternal dietary iodine deficiency but not thiocyanate feeding affects maternal reproduction and postnatal performance of the rat.

Iodine deficiency disorders affect reproductive performance in the afflicted populations. Environmental iodine deficiency (ID) and goitrogens are important in their aetiology. We observed earlier that chronic maternal dietary ID but not goitrogen feeding altered the blood-brain barrier nutrient transport in adult rats. Whether similar differences exist in their effects on reproduction of dams and postnatal performance of the offspring has been assessed. Inbred, female, weaning WNIN rats were rendered hypothyroid by feeding for 8-12 weeks, a low iodine test diet or a control diet with added potassium thiocyanate (KSCN) (@ 25 mg/rat/day). Following mating with control males, they continued on their respective diets till their pups were weaned. Indices of reproductive performance such as percentage of conception, mortality of dams during pregnancy and parturition, litter size, and survival of pups till weaning were affected markedly by ID but not thiocyanate feeding. Neither ID nor thiocyanate feeding from conception or parturition affected their reproductive performance. Nevertheless, postnatal weight gain of pups was less in all the three ID groups but not thiocyanate fed dams. Rehabilitation of chronically ID pregnant dams from conception or parturition did not improve their pregnancy weight gain, litter size or birth weight of pups but decreased abortion and mortality of mothers during pregnancy and parturition. Rehabilitation improved the pups' postnatal weight gain but the effect was only moderate. Based on the results of the present study it may be suggested that maternal ID but not thiocyanate feeding affects reproductive performance and postnatal performance of their offspring.

Profile of iodine content of salt and urinary iodine excretion levels in selected districts of Tamil Nadu.

OBJECTIVE: Iodine deficiency disorders (IDD) is the most common cause of preventable mental retardation in world today. Out of 29 districts in Tamil Nadu, 24 have been surveyed and all have been found to be endemic to IDD. There is a complete ban on the sale of non iodised salt in the state since 1995. The present study was conducted to assess the iodine content of salt and urinary iodine excretion levels amongst the beneficiaries in the state to help the government to strengthen the existing Universal salt iodisation (USI) programme activities. METHODS: The study was undertaken in 24 districts of Tamil Nadu during the year 2001. The guidelines recommended by WHO/UNICEF/ICCIDD for a rapid assessment of salt iodisation in a district was adopted. A minimum of 150 salt samples were collected from each district by utilising the uniform sampling methodology. The iodine content of salt samples was analysed using the standard iodometric titration method. At least 60 children from each school were randomly selected and were requested to provide "on the spot" casual urine samples. The urinary iodine excretion (UIE) levels were analysed using the wet digestion method. RESULTS: It was observed that 62.3% of the families were consuming iodised salt with more than 5 ppm of iodine. It was found that district Perambalour had deficient iodine nutriture as revealed by the median UIE levels less than 100 micro g/l. CONCLUSION: The findings of the present study reveals the success of USI programme and highlights need for continued monitoring of the quality of salt provided to the population in order to achieve the goal of IDD elimination.

Studies on ATP-diphosphohydrolase nucleotide-binding sites by intrinsic fluorescence

Potato apyrase, a soluble ATP-diphosphohydrolase, was purified to homogeneity from several clonal varieties of Solanum tuberosum. Depending on the source of the enzyme, differences in kinetic and physicochemical properties have been described, which cannot be explained by the amino acid residues present in the active site. In order to understand the different kinetic behavior of the Pimpernel (ATPase/ADPase = 10) and Desirée (ATPase/ADPase = 1) isoenzymes, the nucleotide-binding site of these apyrases was explored using the intrinsic fluorescence of tryptophan. The intrinsic fluorescence of the two apyrases was slightly different. The maximum emission wavelengths of the Desirée and Pimpernel enzymes were 336 and 340 nm, respectively, suggesting small differences in the microenvironment of Trp residues. The Pimpernel enzyme emitted more fluorescence than the Desirée apyrase at the same concentration although both enzymes have the same number of Trp residues. The binding of the nonhydrolyzable substrate analogs decreased the fluorescence emission of both apyrases, indicating the presence of conformational changes in the neighborhood of Trp residues. Experiments with quenchers of different polarities, such as acrylamide, Cs+ and I- indicated the existence of differences in the nucleotide-binding site, as further shown by quenching experiments in the presence of nonhydrolyzable substrate analogs. Differences in the nucleotide-binding site may explain, at least in part, the kinetic differences of the Pimpernel and Desirée isoapyrases.

Spectrophotometric determination of fluoxetine and sertraline using chloranil2, 3 dichloro-5, 6 dicyanoquinone and iodine

Spectrophotometric procedures have been presented for the determination of 2 commonly used antidepressant drugs: Fluoxetine [I] and sertraline hydrochloride [II]. The methods have been based mainly on charge transfer complexation reaction of these drugs with either pi acceptors chloranil and 2, 3 dichloro-5, 6-dicyanoquinone [DDQ], or sigma acceptor iodine. The molar combining ratio and the optimum assay conditions were studied. More detailed investigation of the complex formed in chloranil method was made with respect to its composition, association constant Kc Ad, molar absorptivity epsilon lambda AD, and free energy change delta G. The proposed methods were applied successfully to the determination of the cited drugs either in pure or dosage forms with good accuracy and precision

Iodine loss from iodised salt on heating.

Iodine deficiency disorders constitute a major public health problem in India. The national IDD control programme (NIDDCP) relies solely on iodine supplementation through fortification of common salt with potassium iodate. However, data regarding iodine loss due to high temperatures of cooking procedure is scarce. Using iodometric titration methods, we calculated iodine content of iodised salt samples subjected to incremental heat up to 350 degree Celsius. The results of the study indicate a gradual but minimal loss of iodine content from the iodised salt samples when subjected to high temperature with a maximum loss noticed being 18.5% at 350 degree Celsius. We conclude that there is minimal loss of iodine from the salt fortified with potassium iodate when subjected to heating (temperature normally attained during cooling process).

alkoxy iodination, nitratoiodination and acetatoiodination of uridine

Reaction of uridine with iodine and cerium IV ammonium nitrate in both of methanol, ethanol and 2-propanol gave the corresponding 5-iodo-6-alkoxy dihydro uridine, while in the case of use t-butyl alcohol or acetic acid, instead of the previous alcohols, 5-iodo-6-nitrato uridine or 5-iodo-6-acetato dihydro uridine were afforded, respectively