Role of Organic Carbonyl Moiety and 3-Aminopropyltrimethoxysilane on the Synthesis of Gold Nanoparticles Specific to pH- and Salt-Tolerance.

The synthesis of gold nanoparticles (AuNPs) having better dispersibility and catalytic ability than the conventional AuNPs is the challenging task. The fact that aldehydes and ketones results in the formation of catalytic hybrid material with amino functionalized silanes directed the use of carbonyl functional group (aldehydes and ketones) specifically formaldehyde, acetaldehyde, acetone and t-butyl methyl ketone alongwith 3-aminopropyltrimethoxysilane (3-APTMS) to meet such requirement. Accordingly, a comparative study on the synthesis of 3-APTMS and organic reducing agent mediated synthesis of AuNPs are reported herein. The findings reveal that 3-APTMS capped gold ions are converted into AuNPs with precise control of pH- and salt- sensitivity. The major findings reveal the following: (1) 3-APTMS being amphiphilic, dispersibility of as prepared AuNPs largely depends on the organic reducing agents. (2) An increase in the hydrocarbon content of the reducing agent facilitate the dispersibility of AuNPs in organic solvent whereas decrease of the same increases the dispersibility in water, (3) AuNPs made through aldehydic reducing agents (formaldehyde and acetaldehyde) have relatively better salt and pH tolerance as compared to ketonic reducing agents (acetone, t-butyl methyl ketone), and (4) an increase in 3-APTMS concentrations imparts better salt- and pH- resistant property to AuNPs irrespective of organic reducing agents. A typical example on the role of AuNPs in homogeneous catalysis during potassium ferricyanide mediated oxidation of ascorbic acid is also reported.

Interactive toxicity of simple chemical mixtures of cadmium, mercury, methylmercury and trimethyltin: model-dependent responses.

Scientific and societal interest in the analysis of aggregate toxicity derives from the fact that people are seldom exposed to single chemicals, but rather to multiple agents from different sources and even to mixtures of agents from a single source. Many descriptive terms and mathematical, graphical, and statistical models have been used to evaluate the toxicity of simple mixtures. It is not very easy to distinguish clearly the intrinsic differences, distinctions and limitations of these models when applied to characterizing interactive toxicity. A series of experiments were performed to illustrate model-dependent consistencies and differences in interactive toxicity. Cultured murine renal cortical cells, target cells for metal toxicity, were treated with selected concentrations of one metal or binary mixtures of metals to give conditions of dose-additivity, response additivity, or with only one toxic member of the binary mixture. The cytotoxicity was determined at 24h by lactate dehydrogenase release. The data were analyzed graphically and mathematically by (a) Carter's statistical isobologram, (b) Barton's non-linear, and (c) Kodell and Pounds' linear models to characterize the interaction. These models were compared and contrasted for robustness, and consistency using these common data sets. The models gave generally consistent conclusions, but each model has limitations and strengths for assessing particular mixtures scenarios. This comparison illustrates the complexity of extrapolating conclusions between models, and difficulty of public health assessment from exposures to multiple chemicals in the environment.

Assessment of topiramate's efficacy and safety in epilepsy.

OBJECTIVE: To study the significance of topiramate (TPM) addition on seizure control in treatment of epilepsy. DESIGN: A prospective open label add-on trial of TPM addition in patients with epilepsy was done. The events of baseline phase of 12 weeks followed by titration and maintenance phases were recorded. Assessment of the number of seizure and emergent adverse effects was done by a monthly visit for each case. MAIN OUTCOME MEASURES: Reduction of more than 50% mean seizure frequency or response ratio of 0.33 was taken as the criteria for responders. STATISTICAL ANALYSIS: Normal Z-test for significance of differences between two proportions and Chi-square test for presence of association was applied and mean age, median duration, sex ratio, percentage prevalence were depicted. RESULTS: Significant responses to TPM in both partial as well as generalized seizures were observed (Z = 6.66, P < 0.001 and Z = 4.185, P < 0.01). The effect was more pronounced in patients with partial seizures. However, the overall response was highly significant (Z = 7.839, P < 0.001). The best response was noted at the dose of 200-300 mg/day (Z = 6.708, P < 0.001). More than 35% cases of partial and generalized seizures reported more than 75% reduction levels. The drug was well tolerated in more than 65% cases for side effects on psychosis, giddiness, and anorexia. Mild side effects were seen only in about less than 35% cases. CONCLUSIONS: TPM was found as a significantly effective add-on anticonvulsant with some limitation or mild side effects.