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Charge Ratio (charge + ratio)
Selected AbstractsCationic and Anionic Conjugated Polyelectrolytes: Aggregation-Mediated Fluorescence Energy Transfer to Dye-Labeled DNAMACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2008Youngeup Jin Abstract An electrostatic complex of water-soluble conjugated polyelectrolytes (CPs) between anionic poly(9,9-bis(4,-sulfonatobutyl)fluorene- co-alt -1,4-phenylene) disodium salt (a-PFP) and cationic poly(9,9-bis((6,- N,N,N,-trimethylammonium)hexyl)fluorene- co -2,1,3-bezothiadiazole) dibromide (85:15) (c-PFB15) was tested as a fluorescence resonance energy transfer (FRET) donor to Texas Red (TR)-labeled single-stranded DNA (ssDNA-TR) via two-step FRET processes. Electrostatic complexation of a-PFP and c-PFB15 in water leads to aggregation of polymer chains, a concomitant reduction of intersegment distances, and energy transfer to the benzothiadiazole (BT) segments. The following complexation with ssDNA-TR leads to energy transfer from BT to TR via two-step FRET processes. This detection schematic shows an FRET-induced signal amplification, which can be achieved by adjusting the charge ratio in the cationic/anionic CP complex and controlling the number density of the binding CPs around the acceptor, resulting in enhanced antenna effects and sensitivity in CP-based FRET DNA detection assays. [source] Surface Plasmon Resonance Spectroscopy as a Tool to Study Polyplex-Glycoaminoglycan InteractionsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 12 2005Peter Dubruel Abstract Summary: This article reports the application of surface plasmon resonance (SPR) to monitor the interaction between polymer-DNA complexes and glycoaminoglycans (GAG). The GAG selected was hyaluronic acid (HA). First a HA derivative containing a disulfide linkage was synthesized, enabling chemisorption onto a gold surface. Next, the interaction between different complexes (prepared using PEI or PDMAEMA) and HA was studied using SPR. This study clearly indicates that GAG-polyplex interactions depend on the type of polymer selected and on the charge ratio of the polyplexes prepared. The derivative developed opens up new perspectives in the field of nonviral gene delivery. [source] Combination Nonviral Interleukin-2 Gene Immunotherapy For Head and Neck Cancer: From Bench Top to BedsideTHE LARYNGOSCOPE, Issue 3 2005Bert W. O'Malley Jr MD Abstract Objective/Hypothesis: Intralesional delivery of cytokine genes has emerged as a promising therapeutic strategy for the treatment of cancer. In addition to the therapeutic effect of the delivered cytokine gene, the components of the gene delivery system also have been shown to induce beneficial immune responses. On the basis of these principles, we hypothesized that a molecular therapy could be developed that would provide synergistic antitumor activity by way of intralesional expression of interleukin (IL)-2 from a recombinant plasmid combined with induction of endogenous interferon (IFN)-, and IL-12 cytokines by immunostimulatory DNA. Our objective in these studies was to create and optimize a novel formulation of cationic lipid and DNA that generates local production of IL-2 protein within a targeted tumor environment with concomitant induction of the antitumor cytokines IFN-, and IL-12. Study Design: Prospective laboratory drug development plan that would produce human clinical trials. Materials and Methods: Engineered bacterial plasmids containing a cytomegalovirus promoter (CMV)-IL-2 expression cassette were specifically formulated with cationic lipids and optimized for antitumor effect in a floor of mouth murine tumor model. The treated tumors were assayed for local expression of IL-2 and concurrent expression of secondary cytokines IFN-, and IL-12. Established tumors in C3H/HeJ mice were treated with various IL-2 gene formulations, and clinical and immunologic responses were evaluated. Immunologic studies were performed and included cytolytic T-cell assays and cytokine expression profiles. For human clinical trials, a phase I 10 patient formulated IL-2 gene therapy study was completed. Subsequently, two large scale, phase II multi-institutional and multi-international studies were initiated comparing non-viral IL-2 gene therapy to palliative methotrexate chemotherapy or in combination with cisplatin. Results: In the preclinical stage, maximum tumor inhibition in animal models was obtained using IL-2 plasmid formulated with 1,2-dioleyloxypropyl-3-trimethyl ammonium chloride (DOTMA):cholesterol (1:1 mol:mol) at a plasmid:lipid charge ratio of 1:0.5 (,/+). Cationic lipid formulated IL-2 plasmid significantly inhibited tumor growth compared with formulated control plasmid (P < .01) or vehicle (lactose; P < .01). Consistent with previously reported studies of the immunostimulatory activity of DNA of bacterial origin, treatment of tumors with control plasmid in cationic lipid formulation induced production of endogenous IFN-, and IL-12 but not IL-2. Treatment of tumors with formulated IL-2 plasmid produced IL-2 protein levels that were 5-fold over background and increased IFN-, by 32-fold (P < .001) and IL-12 by 5.5-fold (P < .001) compared with control plasmid formulations. The phase I human trial demonstrated dose escalation safety, which was its primary objective, and there was one anecdotal reduction in tumor size. The phase II studies have been initiated and focus on either comparing the novel nonviral IL-2 gene immunotherapy formulation alone to methotrexate or comparing IL-2 gene therapy in combination with cisplatin in recurrent or unresectable patients with head and neck squamous cell carcinoma. Conclusions: The preclinical data provided proof of principle for matching a delivered IL-2 transgene with an immunostimulatory nonviral formulation to enhance intralesional production of therapeutic cytokines for the maximization of antitumor response. Human clinical trials have demonstrated this novel therapy to be safe in the human clinical setting. Phase II trials have been initiated to assess efficacy and feasibility as a single or combination therapy for head and neck cancer. [source] Role of the Preparation Procedure in the Formation of Spherical and Monodisperse Surfactant/Polyelectrolyte ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2007Yuxia Luan Dr. Abstract Complexes formed by a double-tail cationic surfactant, didodecyldimethyl ammonium bromide, and an anionic polyelectrolyte, an alternating copolymer of poly(styrene-alt-maleic acid) in its sodium salt form, were investigated with respect to variation in the charge ratio (x) between the polyelectrolyte negative charges and the surfactant positive charges. The morphology and microstructure of the complexes were studied by light microscopy and small-angle X-ray scattering for different preparation conditions. Independent of the sample preparation procedure and the charge ratio x, the X-ray results show that the microscopic structure of the complexes is a condensed lamellar phase. By contrast, the morphology of the complexes changes dramatically with the preparation procedure. The complexes formed by mixing a surfactant solution and a polyelectrolyte solution strongly depend on x and are always extremely heterogeneous in size and shape. Surprisingly, we show that, when the two solutions interdiffuse slowly, spherical complexes of micrometric and rather uniform size are systematically obtained, independently on the initial relative amount of surfactant and polyelectrolyte. The mechanism for the formation of these peculiar complexes is discussed. [source] Studies on the condensation of depolymerized chitosans with DNA for preparing chitosan-DNA nanoparticles for gene delivery applicationsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Viola B. Morris Abstract High molecular weight chitosan (CS) was depolymerized by oxidative degradation with NaNO2 at room temperature to get 11 samples of CS derivatives of varying molecular weights with a view to assessing their effective molecular weight range for gene delivery applications. Viscosity studies indicated that the molecular weight of the depolymerized CS was proportional to the CS/NaNO2 ratio. The condensation behavior of DNA/CS complexes at various charge ratios was studied using UV spectroscopy, FTIR, CD, SEM, and AFM. The results indicated that CSs having very low molecular weights and high charge density exhibited strong binding affinity to DNA compared to high molecular weight CSs. However, the very low molecular weight (1.9,7.7 kDa) CSs were found to form aggregates easily even at very low charge ratios. On the other hand, CSs having medium molecular weight (49,51 kDa) and high degree of deacetylation (DD) gave stable uniform-sized nanoparticles. Biological studies carried out with the spherical nano-sized polyplexes formed between CS of 50 kDa (DD of 94%) and pEGFP plasmid DNA at N/P ratio of 5.0 showed excellent gene transfection efficiency at pH 6.5 in HeLa cells without cytotoxicity indicating their potential as genedelivery carriers. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Highly efficient gene transfer into hepatocyte-like HepaRG cells: New means for drug metabolism and toxicity studiesBIOTECHNOLOGY JOURNAL, Issue 3 2010Veronique Laurent Abstract HepaRG progenitor cells are capable of differentiating into hepatocyte-like cells that express a large set of liver-specific functions. These cells, however, only express small amounts of an important cytochrome P450, the CYP2E1, which limits their use for toxicological studies of drugs metabolized by this pathway. Our aim was to establish an efficient transfection protocol to increase CYP2E1 expression in HepaRG cells. Transfection protocols of the green fluorescent protein (GFP) reporter gene were evaluated using electroporation and cationic lipids belonging to the lipophosphonates, lipophosphoramidates and lipids derived from glycine betaine. Following optimization of the charge ratios, plasmid DNA and formulations with neutral co-lipids, the lipophosphoramidate compounds KLN47 and BSV10, allowed expression of the GFP in ,50% of adherent progenitor HepaRG cells, while electroporation targeted GFP expression in ,85% of both progenitor and differentiated cells in suspension. Transient enforced expression of active CYP2E1 was also achieved in progenitors and/or differentiated HepaRG cells using the electroporation and the lipophosphoramidate compound BSV10. Importantly, in electroporated cells, CYP2E1 expression level was correlated with a significant increase in CYP2E1-specific enzymatic activity, which opens new perspectives for this CYP-dependent drug metabolism and toxicity studies using HepaRG cells. [source] Human neutrophil peptides 1,3 are useful biomarkers in patients with active ulcerative colitisINFLAMMATORY BOWEL DISEASES, Issue 6 2009Shuji Kanmura MD Abstract Background: A specific useful biomarker for diagnosing ulcerative colitis (UC) has not yet been described. This study employed proteomics to identify serum protein biomarkers for UC. Methods: Ninety-four blood samples were isolated from patients and controls (including 48 UC, 22 Crohn's disease [CD], 5 colorectal cancer, and 6 infectious colitis patients and 13 healthy subjects). Serum samples were analyzed using the SELDI-TOF/MS ProteinChip system. After applying the samples to ProteinChip arrays, we assessed differences in the proteomes using Ciphergen ProteinChip software and identified candidate proteins, which were then characterized in immunoassays. Results: Preliminary analysis using the ProteinChip system revealed significant peak-intensity differences for 27 serum proteins between 11 patients with UC and 7 healthy subjects. Among these proteins, 3 proteins (with mass/charge ratios of approximately 3400) were identified as human neutrophil peptides 1,3 (HNP 1,3). The presence of HNP 1,3 in the patient sera was confirmed using immunoassays. Enzyme-linked immunosorbent assays demonstrated that the mean plasma concentration of HNP 1,3 was significantly higher in patients with active UC (n = 28) than in patients whose UC was in remission (n = 20) or patients with CD (n = 22), infectious colitis, or healthy subjects, and tended to be higher than in patients with colon cancer. In addition, the plasma concentration of HNP 1,3 in patients that responded to corticosteroids-based therapy decreased after treatment, whereas it was not changed in nonresponders. Conclusions: HNP 1,3 is a novel biomarker that may be useful for diagnosing patients with active UC and predicting treatment outcomes. (Inflamm Bowel Dis 2008) [source] Interference of chlorofluorocarbon (CFC)-containing inhalers with measurements of volatile compounds using selected ion flow tube mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2009Michael J. Epton Selected ion flow tube mass spectrometry (SIFT-MS) is a sensitive technique capable of measuring volatile compounds (VCs) in complex gas mixtures in real time; it is now being applied to breath analysis. We investigated the effect of inhalers containing chlorofluorocarbons (CFCs) on the detection and measurement of haloamines in human breath. SIFT-MS mass scans (MS) and selected ion monitoring (SIM) scans were performed on three healthy non-smoking volunteers before and after inhalation of the following medications: CombiventÔ metered-dose inhaler (MDI) (CFC-containing); VentolinÔ MDI (CFC-free); AtroventÔ MDI (CFC-free), BeclazoneÔ MDI (CFC-containing); DuolinÔ nebuliser. In addition, the duration of the persistence of the mass/charge ratios was measured for 20,h. Inhalers containing CFCs generated large peaks at m/z 85, 87, 101, 103 and 105 in vitro and in vivo, consistent with the predicted product ions of CFCs 12, 114 and 11. No such peaks were seen with DuolinÔ via nebuliser, or CFC-free MDIs. We conclude that measurement of VCs, such as haloamines, with product ions of similar m/z values to the ions found for CFCs would be significantly affected by the presence of CFCs in inhalers. This issue needs to be accounted for prior to the measurement of VCs in breath in people using inhalers containing CFCs. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||