Cellular accumulation of Cys326-OGG1 protein complexes under conditions of oxidative stress.

The common Ser326Cys polymorphism in the base excision repair protein 8-oxoguanine glycosylase 1 is associated with a reduced capacity to repair oxidative DNA damage particularly under conditions of intracellular oxidative stress and there is evidence that Cys326-OGG1 homozygous individuals have increased susceptibility to specific cancer types. Indirect biochemical studies have shown that reduced repair capacity is related to OGG1 redox modification and also possibly OGG1 dimer formation. In the current study we have used bimolecular fluorescence complementation to study for the first time a component of the base excision repair pathway and applied it to visualise accumulation of Cys326-OGG1 protein complexes in the native cellular environment. Fluorescence was observed both within and around the cell nucleus, was shown to be specific to cells expressing Cys326-OGG1 and only occurred in cells under conditions of cellular oxidative stress following depletion of intracellular glutathione levels by treatment with buthionine sulphoximine. Furthermore, OGG1 complex formation was inhibited by incubation of cells with the thiol reducing agents ß-mercaptoethanol and dithiothreitol and the antioxidant dimethylsulfoxide indicating a causative role for oxidative stress in the formation of OGG1 cellular complexes. In conclusion, this study has provided for the first time evidence of redox sensitive Cys326-OGG1 protein accumulation in cells under conditions of intracellular oxidative stress that may be related to the previously reported reduced repair capacity of Cys326-OGG1 specifically under conditions of oxidative stress.

Agricultural waste material as potential adsorbent for sequestering heavy metal ions from aqueous solutions - a review.

Heavy metal remediation of aqueous streams is of special concern due to recalcitrant and persistency of heavy metals in environment. Conventional treatment technologies for the removal of these toxic heavy metals are not economical and further generate huge quantity of toxic chemical sludge. Biosorption is emerging as a potential alternative to the existing conventional technologies for the removal and/or recovery of metal ions from aqueous solutions. The major advantages of biosorption over conventional treatment methods include: low cost, high efficiency, minimization of chemical or biological sludge, regeneration of biosorbents and possibility of metal recovery. Cellulosic agricultural waste materials are an abundant source for significant metal biosorption. The functional groups present in agricultural waste biomass viz. acetamido, alcoholic, carbonyl, phenolic, amido, amino, sulphydryl groups etc. have affinity for heavy metal ions to form metal complexes or chelates. The mechanism of biosorption process includes chemisorption, complexation, adsorption on surface, diffusion through pores and ion exchange etc. The purpose of this review article is to provide the scattered available information on various aspects of utilization of the agricultural waste materials for heavy metal removal. Agricultural waste material being highly efficient, low cost and renewable source of biomass can be exploited for heavy metal remediation. Further these biosorbents can be modified for better efficiency and multiple reuses to enhance their applicability at industrial scale.

Removal of nickel(II) from aqueous solution by adsorption on agricultural waste biomass using a response surface methodological approach.

In the present study, effect of adsorbent dose, pH and agitation speed on nickel removal from aqueous medium using an agricultural waste biomass, Sugarcane bagasse has been investigated. Batch mode experiments were carried out to assess the adsorption equilibrium. The influence of three parameters on the removal of nickel was also examined using a response surface methodological approach. The central composite face-centered experimental design in response surface methodology (RSM) by Design Expert Version 6.0.10 (Stat Ease, USA) was used for designing the experiments as well as for full response surface estimation. The optimum conditions for maximum removal of nickel from an aqueous solution of 50 mg/L were as follows: adsorbent dose (1500 mg/L), pH (7.52) and stirring speed (150 rpm). This was evidenced by the higher value of coefficient of determination (r(2)=0.9873).

Removal of cadmium (II) from aqueous solutions by adsorption on agricultural waste biomass.

This paper reports the feasibility of using various agricultural residues viz. sugarcane bagasse (SCB), maize corncob (MCC) and Jatropha oil cake (JOC) for the removal of Cd(II) from aqueous solution under different experimental conditions. Effect of various process parameters, viz., initial metal ion concentration, pH, and adsorbent dose has been studied for the removal of cadmium. Batch experiments were carried out at various pH (2-7), adsorbent dose (250-2000 mg), Cd(II) concentration (5-500 mg l(-1)) for a contact time of 60 min. The maximum cadmium removal capacity was shown by JOC (99.5%). The applicability of Langmuir and Freundlich isotherm suggests the formation of monolayer of Cd(II) ions onto the outer surface of the adsorbents. Maximum metal removal was observed at pH 6.0 with a contact time of 60 min at stirring speed of 250 rpm with an adsorbent dose of 20 g l(-1) of the test solution. The maximum adsorption of cadmium (II) metal ions was observed at pH 6 for all the adsorbents viz; 99.5%, 99% and 85% for JOC, MCC, and SCB, respectively. Order of Cd(II) removal by various biosorbents was JOC>MCC>SCB. JOC may be an alternative biosorbent for the removal of Cd(II) ions from the aqueous solution. FT-IR spectra of the adsorbents (before use and after exhaustion) were recorded to explore number and position of the functional groups available for the binding of Cd(II) ions on to studied adsorbents. These results can be helpful in designing a batch mode system for the removal of cadmium from dilute wastewaters.

Removal of hexavalent chromium from aqueous solution by agricultural waste biomass.

In the present study adsorption of Cr(VI) from aqueous solutions onto different agricultural wastes, viz., sugarcane bagasse, maize corn cob and Jatropha oil cake under various experimental conditions has been studied. Effects of adsorbent dosage, Cr(VI) concentration, pH and contact time on the adsorption of hexavalent chromium were investigated. The concentration of chromium in the test solution was determined spectrophotometrically. FT-IR spectra of the adsorbents (before use and after exhaustion) were recorded to explore number and position of the functional groups available for the binding of chromium ions on to studied adsorbents. SEMs of the adsorbents were recorded to explore the morphology of the studied adsorbents. Maximum adsorption was observed in the acidic medium at pH 2 with a contact time of 60min at 250rpm stirring speed. Jatropha oil cake had better adsorption capacity than sugarcane bagasse and maize corn cob under identical experimental conditions. The applicability of the Langmuir and Freundlich adsorption isotherms was tested. The results showed that studied adsorbents can be an attractive low cost alternative for the treatment of wastewaters in batched or stirred mode reactors containing lower concentrations of chromium.

Permeation enhancers for transdermal drug delivery.

The transdermal route has been recognized as one of the highly potential routes of systemic drug delivery and provides the advantage of avoidance of the first-pass effect, ease of use and withdrawal (in case of side effects), and better patient compliance. However, the major limitation of this route is the difficulty of permeation of drug through the skin. Studies have been carried out to find safe and suitable permeation enhancers to promote the percutaneous absorption of a number of drugs. The present review includes the classification of permeation enhancers and their mechanism of action; thus, it will help in the selection of a suitable enhancer(s) for improving the transdermal permeation of poorly absorbed drugs.