196,180 research outputs found
Uporaba programa COSMOS/M Ver. 1.75 for Windows NT&95 za računanje konstrukcij v gradbeništvu : diplomsko delo visokošolskega študija
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REVERSIBLY STABLE THIOPOLYPLEXES FOR INTRACELLULAR DELIVERY OF GENES
No full textNovel polyaspartamide non-viral carriers for gene therapy were synthesized by introducing, on the same polymer backbone, positively charged
groups, for electrostatic interactions with DNA, and thiol groups for the formation of disulfide bridges between polymer chains. The introduction
of thiols was aimed to have a vector with low redox potential sensitivity: disulfide crosslinking in fact, being stable in extracellular environment,
allowed either to have stable complexes in plasma, that can protect DNA from metabolism, or to be reduced inside the cell, where the excess of
glutathion in reduced form maintains a low redox potential. The consequent destabilization of the complex after disulfide cleavage can release
DNA selectively inside the cells.
α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) was used as starting polymer being a highly water-soluble synthetic polymer, already
proposed with success as therapeutic carrier by our group. In this study, PHEA was firstly functionalised with ethylendiamine, obtaining a well
defined copolymer with pendant primary amine groups (PHEA-EDA), to which N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) and 3-
(carboxypropyl)trimethyl-ammonium chloride (CPTA) were linked in two subsequent steps, allowing the introduction of thiol and cationic groups
respectively. Finally DTT treatment lead to the final PHEA-EDA-SH-CPTA thiopolycation, named PESC.
The present work describes the synthesis and characterization of the thiopolycation PESC. 1H NMR spectroscopy detected the derivatization
molar degrees in SPDP and CPTA; the formation of DNA complexes (thiopolyplexes), their stability in the presence of polyanions and the ability
to release DNA under reductive conditions were studied by agarose gel electrophoresis. DNase II degradation study was carried out to detect the
ability of thiopolyplex to stabilize DNA towards enzymatic metabolism. Thiopolyplexes were then characterized by Dynamic Light Scattering
(DLS) and Zeta Potential analysis. Finally, in vitro toxicity profile (MTT) and gene transfer efficiency (Luciferase assay) were carried out to
evaluate thiopolyplex biocompatibility, safety and efficacy to be used as gene delivery system.
© 2006 Elsevier B.V. All rights reserved
Polyhydroxyethylaspartamide-spermine copolymers: Efficient vectors for gene delivery
No full textAim of this paper was that to prepare biocompatible, polyaspartamide based copolymers containing spermine
or spermine/hydrophobic side chains able to condense nucleic acids and to transfect mammalian cells.
Copolymers were prepared starting from α,β-poly-(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) and exploiting
the reactive hydroxyl groups in the polymeric side chains by subsequent activation reactions to obtain PHEASpermine
(PHEA-Spm) and PHEA-Spermine-Butyramide (PHEA-Spm-C4). Molecular, physico-chemical and
biological characterization of copolymers and interpolyelectrolyte complexes with plasmid DNAwas performed.
Experimental results evidenced that these copolymers are able to form complexes with plasmid DNA already at
low polycation/DNAweight ratio ranging from 0.75/1 to 2/1. Interpolyelectrolyte complexes with decreased size
were obtained when increasing the polycation/DNA weight ratio, until nanosized dimensions were reached.
Copolymers aswell as complexeswere not haemolytic and non toxic in vitro. In vitro cell transfection with PHEA
derivatives showed good biocompatibility and high transfection efficiency (luciferase) in cancer cells in
comparison with commercially available, but toxic transfection agents
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
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