To understand how DNA is released from cationic liposome/DNA complexes in cells, we investigated which biomolecules mediate release of DNA from a complex with cationic liposomes. Release from monovalent[1,2-dioleoyl-3(1)-1(trimethylammonio)propane] or multivalent (dioctadecylamidoglycylspermine) lipids was quantified by an increase of ethidium bromide (EtBr) fluorescence. Plasmid sensitivity to DNAse I degradation was examined using changes in plasmid migration on agarose gel electrophoresis. Physical separation of the DNA from the cationic lipid was confirmed and quantified on sucrose density gradients. Anionic liposomes containing compositions that mimic the cytoplasmic-facing monolayer of the plasma membrane (e.g. phosphatidylserine) rapidly released DNA from the complex. Release occurred near a 1/1 charge ratio (-/+) and was unaffected by ionic strength or ion type. Water soluble molecules with a high negative linear charge density such as dextran sulfate or heparin also released DNA. However, ionic water soluble molecules such as ATP, tRNA, DNA, poly(glutamic acid), spermidine, spermine, or histone did not, even at 100-fold charge excess (-/+). On the basis of these results, we propose that after the cationic lipid/DNA complex is internalized into cells by endocytosis it destabilizes the endosomal membrane. Destabilization induces flip-flop of anionic lipids from the cytoplasmic-facing monolayer, which laterally diffuse into the complex and form a charge neutral ion pair with the cationic lipids. This results in displacement of the DNA from the cationic lipid and release of the DNA into cytoplasm. This mechanism accounts for a variety of observations on cationic lipid/DNA complex-cell interactions.

Cationic lipid-nucleic acid complexes (lipoplexes) consisting of dioleoyltrimethylammoniumpropane (DOTAP) liposomes and plasmid DNA were prepared at various charge ratios (cationic group to nucleotide phosphate), and the excess component was separated from the lipoplex. We measured the stoichiometry of the lipoplex, noted its colloidal properties, and observed its morphology and structure by electron microscopy. The colloidal properties of the lipoplexes were principally determined by the cationic lipid/DNA charge ratio and were independent of the lipid composition. In lipoplexes, the lipid membranes as observed in freeze-fracture electron microscopy were deformed into high-radius-of-curvature features whose characteristics depended on the lipid composition. Lipoplexes prepared at a threefold or greater excess of either DOTAP or DNA could be resolved into complexes with a defined stoichiometry and the excess component by sedimentation to equilibrium on sucrose gradients. The separated, positively charged complex retained high transfection activity and had reduced toxicity. The negatively charged lipoplex showed increased transfection activity compared to the starting mixture. In cryoelectron micrographs the positively charged complex was spherical and contained a condensed but indistinct interior structure. In contrast, the separated negatively charged lipoplexes had a prominent internal 5.9 +/- 0.1-nm periodic feature with material projecting as spikes from the spherical structure into the solution. It is likely that these two lipoplexes represent structures with different lipid and DNA packing.

BackgroundA number of studies have been conducted to investigate the risk of metabolic syndrome (MS) after gestational diabetes mellitus (GDM), but the results are contradictory. Accordingly, we performed a systematic review and meta-analysis to assess the association between these two conditions. The aim was to better understand the risks of MS with prior gestational diabetes.MethodsPubmed, ISI Web of Science, and Cochrane databases from September 1, 1979 to July 11, 2013 were searched to identify relevant studies. 17 studies containing 5832 women and 1149 MS events were included. We calculated the odds ratio (OR) with 95% confidence interval (CI) in analysis for each study using a random-effect or fixed-effect model. We also determined heterogeneity among these 17 articles and their publication bias.ResultsWomen with a history of gestational diabetes had a significantly higher risk of MS than those who had a normal pregnancy (OR, 3.96; 95% CI, 2.99 to 5.26), but had significant heterogeneity (I 2 = 52.6%). The effect remained robust (OR, 4.54; 95% CI, 3.78–5.46) in the subgroup of Caucasians, but no association (OR, 1.28; 95% CI, 0.64–2.56) was found in Asians. Heterogeneity was reduced (body mass index (BMI) matched group I 2 = 14.2%, BMI higher in the GDM group I 2 = 13.2%) in the subgroup of BMI. In addition, mothers with higher BMI in the GDM group had higher risk of MS than those in the BMI matched group (BMI higher in GDM group OR, 5.39; 95% CI, 4.47–6.50, BMI matched group OR, 2.53; 95% CI, 1.88–3.41).ConclusionsThis meta-analysis demonstrated increased risk of MS after gestational diabetes. Therefore, attention should be given to preventing or delaying the onset of MS in GDM mothers, particularly in Caucasian and obese mothers.

Magnetically coupled resonance wireless power transfer systems (MCR WPT) have been developed in recent years. There are several key benefits of such systems, including dispensing with power cords, being able to charge multiple devices simultaneously, and having a wide power range. Hence, WPT systems have been used to supply the power for many applications, such as electric vehicles (EVs), implantable medical devices (IMDs), consumer electronics, etc. The literature has reported numerous topologies, many structures with misalignment effects, and various standards related to WPT systems; they are usually confusing and difficult to follow. To provide a clearer picture, this paper aims to provide comprehensive classifications for the recent contributions to the current state of MCR WPT. This paper sets a benchmark in order to provide a deep comparison between different WPT systems according to different criteria: (1) compensation topologies; (2) resonator structures with misalignment effects; and, (3) electromagnetic field (EMF) diagnostics and electromagnetic field interference (EMI), including the WPT-related standards and EMI and EMF reduction methods. Finally, WPT systems are arranged according to the application type. In addition, a WPT case study is proposed, an algorithm design is given, and experiments are conducted to validate the results obtained by simulations.