APTAMER: A REVIEW ON IT’S IN VITRO SELECTION AND DRUG DELIVERY SYSTEM

In recent year, Aptamer has been one of the key tools in the field of advanced drug delivery systems. Aptamer are oligonucleotides or peptides that bind to a specific target molecule. In this review we summarize the major differences between the antibody and an Aptamer along with the different methodology of the In vitro selection of the Aptamer by using SELEX (Systematic evolution of ligands by exponential enrichment) technique. SELEX is a technique which has a based biosensor and some of the novel drug delivery system. The article referred in this review was referred from the above said source was in the range of 1990-2020 y. Primary contents is searched from science direct, springer nature, scopus indexed journals. The resources are downloaded from google scholar, peer-reviewed published literature from scientific journals and books

Removal of PCR Error Products and Unincorporated Primers by Metal-Chelate Affinity Chromatography

Immobilized Metal Affinity Chromatography (IMAC) has been used for decades to purify proteins on the basis of amino acid content, especially surface-exposed histidines and “histidine tags” genetically added to recombinant proteins. We and others have extended the use of IMAC to purification of nucleic acids via interactions with the nucleotide bases, especially purines, of single-stranded RNA and DNA. We also have demonstrated the purification of plasmid DNA from contaminating genomic DNA by IMAC capture of selectively-denatured genomic DNA. Here we describe an efficient method of purifying PCR products by specifically removing error products, excess primers, and unincorporated dNTPs from PCR product mixtures using flow-through metal-chelate affinity adsorption. By flowing a PCR product mixture through a Cu2+-iminodiacetic acid (IDA) agarose spin column, 94–99% of the dNTPs and nearly all the primers can be removed. Many of the error products commonly formed by Taq polymerase also are removed. Sequencing of the IMAC-processed PCR product gave base-calling accuracy comparable to that obtained with a commercial PCR product purification method. The results show that IMAC matrices (specifically Cu2+-IDA agarose) can be used for the purification of PCR products. Due to the generality of the base-specific mechanism of adsorption, IMAC matrices may also be used in the purification of oligonucleotides, cDNA, mRNA and micro RNAs

Tractography passes the test: Results from the diffusion-simulated connectivity (disco) challenge.

Estimating structural connectivity from diffusion-weighted magnetic resonance imaging is a challenging task, partly due to the presence of false-positive connections and the misestimation of connection weights. Building on previous efforts, the MICCAI-CDMRI Diffusion-Simulated Connectivity (DiSCo) challenge was carried out to evaluate state-of-the-art connectivity methods using novel large-scale numerical phantoms. The diffusion signal for the phantoms was obtained from Monte Carlo simulations. The results of the challenge suggest that methods selected by the 14 teams participating in the challenge can provide high correlations between estimated and ground-truth connectivity weights, in complex numerical environments. Additionally, the methods used by the participating teams were able to accurately identify the binary connectivity of the numerical dataset. However, specific false positive and false negative connections were consistently estimated across all methods. Although the challenge dataset doesn't capture the complexity of a real brain, it provided unique data with known macrostructure and microstructure ground-truth properties to facilitate the development of connectivity estimation methods

Power Quality Improvement by Direct Power Control of Active Front End Rectifier

339-342Active fronts End Rectifiers (AFE) are used as a powerful tool for Harmonic Mitigation. This paper proposes a new development of Direct Power Control (DPC) in AFE Rectifier technologies that are utilized to mitigate harmonics in utility power lines. In this paper, Voltage Oriented Control (VOC) based Direct Power control (DPC) of three phases PWM Rectifier with reduced input harmonics and improved power factor is presented. In the proposed Direct Power Control based on Voltage Oriented Control scheme, instantaneous active and reactive powers provided by harmonic component of input currents are directly controlled using predefined switching table with 12 switching states. A complete simulation model is developed using MATLAB/Simulink in order to test the performance of VOC based DPC of PWM rectifier and compared with SVPWM based AFE Rectifier. Results show effective harmonic compensation at front end for DPC based PWM rectifier and the current THD is 3.3% which is well below the IEEE standards. Also almost unity power factor is achieved with significant power ripple reduction and more sinusoidal grid current can be observed in DPC

Negative regulation of p120GAP GTPase promoting activity by p210bcr/abl: implication for RAS-dependent Philadelphia chromosome positive cell growth.

The p210bcr/abl tyrosine kinase appears to be responsible for initiating and maintaining the leukemic phenotype in chronic myelogenous leukemia (CML) patients. p21ras-p120GAP interactions play a central role in transducing mitogenic signals. Therefore, we investigated whether p21ras and p120GAP are regulated by p210bcr/abl, and whether this activation is functionally significant for CML cell proliferation. We report that transient expression of p210bcr/abl in fibroblast-like cells induces simultaneous activation of p21ras and inhibition of GTPase-promoting activity of p120GAP, and confirm these data showing that downregulation of p210bcr/abl expression in CML cells with bcr/abl antisense oligodeoxynucleotides induces both inhibition of p21ras activation and stimulation of GTPase-promoting activity of p120GAP. Tyrosine phosphorylation of two p120GAP-associated proteins, p190 and p62, which may affect p120GAP activity, also depends on p210bcr/abl tyrosine kinase expression. Direct dependence of these effects on the kinase activity is proven in experiments in which expression of c-MYB protein in fibroblast-like cells or downregulation of c-MYB expression resulting in analogous inhibition of CML cell proliferation does not result in the same changes. Use of specific antisense oligodeoxynucleotides to downregulate p21ras expression revealed a requirement for functional p21ras in the proliferation of Philadelphia chromosome-positive CML primary cells. Thus, the p210bcr/abl-dependent regulation of p120GAP activity is responsible, in part, for the maintenance of p21ras in the active GTP-bound form, a crucial requirement for CML cell proliferation