Symbolic agglomerative clustering for quantitative analysis of remotely sensed data

An efficient nonparametric, hierarchical, symbolic agglomerative clustering procedure based on the mutual nearest neighbourhood concept is proposed for classifying remotely sensed multispectral data. The procedure utilized a data reduction technique and an innovative symbolic concept to minimize the memory and computational time requirements. A new non-metric similarity measure and a novel method of formulation of composite symbolic objects are proposed to enrich the performance of the algorithm. A Mean Difference Index (MDI) concept for identifying the optimal number of classes was used. Experiments were conducted on IRS (Indian Remote Sensing) satellite data to authenticate the efficacy of the procedure.     

Analysis of stress responsive genes induced by single-walled carbon nanotubes in BJ Foreskin cells

Nanotechnology is finding its use as a potential technology in consumer products, defense, electronics, and medical applications by exploiting the properties of nanomaterials. Single-walled carbon nanotubes are novel forms of these nanomaterials with potential for large applications. However, the toxicity studies on this material are not explored in detail and therefore limiting its use. It has been earlier reported that single-walled carbon nanotubes induces oxidative stress and also dictates activation of specific signaling pathway in keratinocytes. The present study explores the effect of single-walled carbon nanotubes on stress genes in human BJ Foreskin cells. The results show induction of oxidative stress in BJ Foreskin cells by single-walled carbon nanotubes and increase in stress responsive genes. The genes included inducible genes like HMOX1, HMOX2, and Cyp1B1. In addition we validated increase for four genes by SWCNT, namely ATM, CCNC, DNAJB4, and GADD45A by RT-PCR. Moreover results of the altered stress related genes have been discussed and that partially explains some of the toxic responses induced by single-walled carbon nanotubes.     

Single-walled carbon nanotubes induces oxidative stress in rat lung epithelial cells

Single-walled carbon nanotubes (SWCNT) show unique properties find applications in micro devices; electronics to biological systems specially drug delivery and gene therapy. However the manufacture and extensive use of nanotubes raises concern about its safe use and human health. Very few studies have been carried out on toxicity of carbon nanotubes in experimental animals and humans, thus resulted in limiting their use. The extensive toxicological studies using in vitro and in vivo models are necessary and are required to establish safe manufacturing guidelines and also the use of SWCNT. These studies also help the chemists to prepare derivative of SWCNT with less or no toxicity. The present study was undertaken to determine the toxicity exhibited by SWCNT in rat lung epithelial cells as a model system. Lung epithelial cells (LE cells) were cultured with or without SWCNT and reactive oxygen species (ROS) produced were measured by change in fluorescence using dichloro fluorescein (DCF). The results show increased ROS on exposure to SWCNT in a dose and time dependent manner. The decrease in glutathione content suggested the depletion and loss of protective mechanism against ROS in SWCNT treated cells. Use of rotenone, the inhibitor of mitochondrial function have no effect on ROS levels suggested that mitochondria is not involved in SWCNT induced ROS production. Studies carried out on the effect of SWCNT on superoxide dismutase (SOD-1 and SOD-2) levels in LE cells, indicates that these enzyme levels decreased by 24 hours. The increased ROS induced by SWCNT on LE cells decreased by treating the cells with 1 mM of glutathione, N-Acetyl Cysteine, and Vitamin C. These results further prove that SWCNT induces oxidative stress in LE cells and shows loss of antioxidants.