Methylated N-(4-N,N-dimethylaminobenzyl) chitosan for novel effective gene carriers

The objective of this study was to investigate the transfection efficiency of quaternized N-(4-N,N-dimethylaminobenzyl) chitosan, TM(47)-Bz(42)-CS, using the plasmid DNA encoding green fluorescent protein (pEGFP-C2) on human hepatoma cell lines (Huh7 cells), in comparison to quaternized chitosan (TM(43)-CS) and chitosan (CS). Factors affecting the transfection efficiency, such as the carrier/DNA weight ratio, the pH of the culture medium, and the presence of serum, have been investigated. The results revealed that TM(47)-Bz(42)-CS was able to condense with pDNA. As illustrated by the agarose gel electrophoresis, the complete complexes of TM(47)-Bz(42)-CS/DNA were formed at a weight ratio of above 0.5, whereas those of TM(43)-CS/DNA and CS/DNA were formed at a ratio of above 1. TM(47)-Bz(42)-CS showed superior transfection efficiency to TM(43)-CS and CS at all weight ratios tested. Higher transfection efficiency and gene expression were observed when the carrier/DNA weight ratios increased. The highest transfection efficiency was found at a weight ratio of 8. The results indicated that the improved gene transfection was due to the hydrophobic group (N,N-dimethylaminobenzyl) substitution on CS, which promoted the interaction and condensation with DNA, as well as N-quaternization, which increased the CS water solubility. During cytotoxicity studies, it was found that high concentrations of TM(47)-Bz(42)-CS and TM(43)-CS could decrease the Huh7 cell viability. In conclusion, this novel CS derivative, TM(47)-Bz(42)-CS, shows promising potential as a gene carrier by efficient DNA condensation and a mediated higher level of gene transfection in Huh7 cells.     

Physicochemical properties of lipid emulsions formulated with high-load all-trans-retinoic acid

The objective of this study was to formulate high loading with good stability of all-trans retinoic acid (ATRA) lipid emulsion. Lipid emulsions loaded with ATRA were composed of lecithin, medium chain triglyceride and poloxamer-188 or polysorbate-80. The formulation factors in a particular type and amount of oil, emulsifier, and co-emulsifier on the physicochemical properties (i.e., particle size, size distribution, droplets surface charge, pH, percentage yield, drug release, and stability of lipid emulsions) were studied. The particle size of ATRA-loaded lipid emulsions was in the nano-size range of 124.4-378.2 nm with the narrow polydispersity index of 0.04-0.09, which decreased as the amount of co-emulsifiers was increased. The amount of ATRA released from lipid emulsions was operated using a dialysis bag. The receptor medium was ethanol:polysorbate-80:water (10:15:75), adjusted to pH 8.5. ATRA release kinetics in this study were found to follow zero-order kinetics. As the concentration of co-emulsifiers increased, the flux of ATRA released from the lipid emulsions increased. In stability studies, the higher the amount of co-emulsifiers added, the lower the crystallization of ATRA was found. The percentage yield of ATRA was retained at about 70-90% and 60-72% after storage for 60 days at 4 degrees C and 25 degrees C, respectively. These results show a successful incorporation of ATRA into lipid emulsions with high loading capacity and good stability.     

West Nile Virus,Texas, USA, 2012

During the 2012 West Nile virus outbreak in Texas, USA, 1,868 cases were reported. Male patients, persons >65 years of age, and minorities were at highest risk for neuroinvasive disease. Fifty-three percent of counties reported a case; 48% of case-patients resided in 4 counties around Dallas/Fort Worth. The economic cost was >$47.6 million.     

Development of meloxicam-loaded electrospun polyvinyl alcohol mats as a transdermal therapeutic agent

This study reports on the use of electrospun polyvinyl alcohol (PVA) nanofiber mats loaded with meloxicam (MX) as a transdermal drug delivery system. The amounts of MX loaded in the base PVA solution (10% w/v solution) were 2.5, 5, 10 and 20% weight, based on the dry weight of PVA (% wt). The average diameters of these fibers ranged from 121-185 nm. In all concentrations of MX loaded in spun PVA fiber mats, an amorphous nanodispersion of MX with PVA was obtained. Both the degree of swelling and the weight loss of the electrospun PVA mats were greater than those of the as-cast PVA films. The tensile strength of the as-spun fiber mats was lower than that of the as-cast PVA films, but the strain at the maximum of the as-spun fiber mats was about six times higher than that of the as-cast PVA films. The skin permeation flux of the MX permeated from MX-loaded as-spun PVA were significantly higher than from MX-loaded as-cast PVA films, and increased when the MX content in both MX-loaded as-spun PVA and MX-loaded as-cast PVA films was increased. Our research suggests a potential use for MX-loaded electrospun PVA mats as a transdermal drug delivery system.     

Carbohydrate Taste Is Associated with Food Intake and Body Mass in Healthy Australian Adults

Background: The taste of carbohydrates may drive their intake. Sensitivity to carbohydrate taste varies among individuals, thus, it is important to understand how differences in sensitivity influence eating behaviour and body mass. Objective: The aims of this study were to assess associations among carbohydrate taste sensitivity, habitual and acute food intake, and body mass; as well as assess the reliability of the carbohydrate detection threshold (DT) test within and across days. Methods: Carbohydrate DT was assessed six times across three sessions in 36 healthy adult participants (22 female) using a three-alternate forced choice methodology. Moreover, 24 h diet records were completed on the days prior to testing sessions, and food intake at a buffet lunch was collected following each session. Anthropometry was also measured. Linear mixed regression models were fitted. Results: The DT test required at least three measures within a given day for good reliability (ICC = 0.76), but a single measure had good reliability when compared at the same time across days (ICC = 0.54–0.86). Carbohydrate DT was associated with BMI (kg/m²: β = −0.38, p = 0.014), habitual carbohydrate intake (g: β = −41.8, p = 0.003) and energy intake (kJ: β = −1068, p = 0.019) from the 24-h diet records, as well as acute intake of a buffet lunch (food weight (g): β = −76.1, p = 0.008). Conclusions: This suggests that individuals who are more sensitive to carbohydrate are more likely to consume greater quantities of carbohydrates and energy, resulting in a greater body mass.     

Chitosan-Thiamine Pyrophosphate as a Novel Carrier for siRNA Delivery

Purpose  A novel siRNA carrier was formulated between chitosan (CS) and thiamine pyrophosphate (TPP). Their ability to deliver siRNA were evaluated in stable and constitutive EGFP-expressing HepG2 cells. Methods  CS-TPP was prepared by dissolving CS in TPP solution at a CS:TPP molar ratio of 1.5:1. Complexes of CS-TPP/siRNA were formed at varying weight ratios and characterized using gel electrophoresis. Their morphologies and particle sizes were evaluated, and the transfection efficiency and cytotoxicity of CS-TPP/siRNA complexes were examined in stable and constitutive EGFP-expressing HepG2 cells. Results  Gel electrophoresis results indicated that binding of CS-TPP and siRNA depended on the molecular weight (MW) and weight ratio of CS, and the particle sizes of CS-TPP/siRNA complexes were in nano-size. The CS-TPP-mediated siRNA silencing of the endogenous EGFP gene occurred maximally with 70–73% efficiency. The CS-TPP/siRNA complex with the lowest MW of CS (20 kDa) at a weight ratio of 80 showed the strongest inhibition of gene expression, which was higher than Lipofectamine 2000™. Over 90% the average cell viabilities of the complexes were observed by MTT assay. Conclusions  This study suggests that CS-TPP is straightforward to prepare, safe and exhibits significantly improved siRNA delivery potential in vitro.     

Evaluation of chitosan salts as non-viral gene vectors in CHO-K1 cells

The aim of this study was to investigate chitosan/DNA complexes formulated with various chitosan salts (CS) including chitosan hydrochloride (CHy), chitosan lactate (CLa), chitosan acetate (CAc), chitosan aspartate (CAs) and chitosan glutamate (CGl). They were assesed for their DNA complexing ability, transfection efficiency in CHO-K1 (Chinese hamster ovary) cells and their effect on cell viability. CHy, CLa, CAc, CAs and CGl, MW 45kDa formed a complex with pcDNA3-CMV-Luc at various N/P ratios. CGl/DNA complexes were formulated with various chitosan molecular weights (20, 45, 200 and 460kDa). The CS/DNA complexes were characterized by agarose gel electrophoresis and investigated for their transfection efficiency in CHO-K1 cells. The cytotoxicity of the complexes was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay in CHO-K1 cells. Gel electrophoresis illustrated that complete complexes formed at N/P ratios above 2 in all CS of MW 45kDa. The transfection efficiency of CS/DNA complexes was dependent on the salt form and MW of chitosan, and the N/P ratio of CS/DNA complexes. Of different CS, the maximum transfection efficiency was found in different N/P ratios. CHy/DNA, CLa/DNA, CAc/DNA, CAs/DNA and CGl/DNA complexes showed maximum transfection efficiencies at N/P ratios of 12, 12, 8, 6 and 6, respectively. Cytotoxicity results showed that all CS/DNA complexes had low cytotoxicity. This study suggests CS have the potential to be used as safe gene delivery vectors.     

Effect of Solid Lipid Nanoparticles Formulation Compositions on Their Size,Zeta Potential and Potential for <Emphasis Type="BoldItalic">In Vitro</Emphasis> pHIS-HIV-Hugag Transfection

Purpose This work was conducted to determine model equations describing the effect of solid lipid nanoparticles (SLN) formulation compositions on their size and zeta potential using the face-centered central composite design and to determine the effect of SLN formulation compositions on the potential for in vitro pHIS-HIV-hugag transfection. Materials and Methods SLN were prepared by the hot high pressure homogenization technique using cetylpalmitate as lipid matrix at varying concentrations of Tween 80 and Span 85 mixture, dimethyldioctadecyl ammonium bromide (DDAB) and cholesterol. Size and zeta potential used as responses of the design were measured at pH 7.0. The model equations were accepted as statistical significance at p value of less than 0.05. Ability of SLN to form complex with pHIS-HIV-hugag was evaluated by electrophoretic mobility shift assay. In vitro cytotoxicity of SLN was studied in HeLa cells using alamar blue bioassay. The potential of SLN for in vitro pHIS-HIV-hugag transfection was also determined in HeLa cells by western blot technique. Results SLN possessed diameter in a range of 136–191 nm and zeta potential 11–61 mV depending on the concentrations of surfactant mixture, DDAB and cholesterol. The regression analysis showed that the model equations of responses fitted well with quadratic equations. The ability of SLN to form complex with pHIS-HIV-hugag was also affected by formulation compositions. In vitro cytotoxicity results demonstrated that HeLa cells were not well tolerant of high concentrations of SLN but still survived in a range of 100–200 μg/ml of SLN in culture medium. The results of transfection study showed ability of SLN to use as a vector for in vitro pHIS-HIV-hugag transfection. However, their potential for in vitro transfection was lower than the established transfection reagent. Conclusions Size and zeta potential of SLN could be predicted from their quadratic model equations achieved by combination of three variables surfactant, DDAB and cholesterol concentrations. In addition, these variables also affected the potential of SLN as a vector for in vitro pHIS-HIV-hugag transfection. The results here provide the framework for further study involving the SLN formulation design for DNA delivery.