Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Context: Nonviral vectors based on polyethylenimine (PEI) usually contain an excess of PEI that is not complexed to DNA. Since unbound PEI contributes to cellular and systemic toxicity, purification of polyplexes from unbound PEI is desirable.', 'Size exclusion chromatography (SEC) was used to purify PEI polyplexes of free PEI. Transfection properties of purified polyplexes and the effect of free PEI on gene delivery were studied in vitro and in vivo after systemic application into mice.', 'SEC did not change the size and zeta-potential of polyplexes. Independent of the amount of PEI used for complex formation, purified PEI polyplexes had the same final PEI nitrogen/DNA phosphate ratio of 2.5. Notably, purified PEI polyplexes demonstrated low cellular and systemic toxicity. High transfection efficiency was achieved with purified polyplexes at high DNA concentrations (8-15 microg/ml). At low DNA concentrations (2-4 microg/ml) gene transfer with purified particles was less efficient than with polyplexes containing free PEI both in vitro and in vivo. Mechanistic studies showed that free PEI partly blocked cellular association of DNA complexes but was essential for the following intracellular gene delivery. Adding free PEI to cells treated with purified particles with a delay of up to 4 h resulted in significantly enhanced transfection efficiency compared with non-purified particles or purified particles without free PEI.
Answer: This study presents an efficient method to remove free PEI from PEI polyplexes by SEC. Our results from transfection experiments demonstrate that free PEI substantially contributes to efficient gene expression but also mediates toxic effects in a dose-dependent manner. Purified polyplexes without free PEI have to be applied at increased concentrations to achieve high transfection levels, but exhibit a greatly improved toxicity profile.
Does purification of polyethylenimine polyplexes highlight the role of free polycations in gene transfer?

Context: Loss-of-function mutations in the progranulin gene (PGRN) were identified in frontotemporal lobar degeneration (FTLD) with ubiquitin-immunoreactive neuronal inclusions (FTLD-U). We assessed whether PGRN also contributes to genetic risk for Alzheimer disease (AD) in an extended Belgian AD patient group (n = 779, onset age 74.7 +/- 8.7 years).', 'A mutation analysis of the PGRN coding region was performed. The effect of missense mutations was assessed using in silico predictions and protein modeling. Risk effects of common genetic variants were estimated by logistic regression analysis and gene-based haplotype association analysis.', 'We observed seven missense mutations in eight patients (1.3%). Convincing pathogenic evidence was obtained for two missense mutations, p.Cys139Arg and p.Pro451Leu, affecting PGRN protein folding and leading to loss of PGRN by degradation of the misfolded protein. In addition, we showed that PGRN haplotypes were associated with increased risk for AD.
Answer: Our data support a role for PGRN in patients with clinically diagnosed Alzheimer disease (AD). Further, we hypothesize that at least some PGRN missense mutations might lead to loss of functional protein. Whether the underlying pathology in our cases proves to be AD, frontotemporal lobar degeneration, or a combination of the two must await further investigations.
Does genetic variability in progranulin contribute to risk for clinically diagnosed Alzheimer disease?

Context: Interleukin-6 (IL-6) is a vital inflammatory factor in the peritoneal cavity of peritoneal dialysis (PD) patients. Because intraperitoneal inflammation is closely associated with angiogenesis, we sought to explore the effect of IL-6 on vascular endothelial growth factor (VEGF) synthesis and its transduction pathway in mesothelial cells.', 'Human mesothelial cells (Met-5A) were incubated with different concentrations of glucose and mannitol, and the effect of glucose and mannitol on the expression of IL-6 was determined. Then, the cells were stimulated by IL-6 with or without two soluble receptors of IL-6 (sIL-6R or sgp130), and VEGF synthesis was detected. Finally, the cells were incubated with IL-6/sIL-6R combined with or without the inhibitor of Janus kinases (JAK) AG490. The phosphorylation of the signal transducer and activator of transcription 3 (STAT3) and its intracellular translocation were examined.', '1. High glucose and mannitol could up-regulate IL-6 mRNA expression and IL-6 secretion in mesothelial cells significantly, and there was no difference of its effect between high glucose and mannitol. 2. Met-5A was a cell line with a single IL-6 receptor. The IL-6/sIL-6R complex induced VEGF synthesis of mesothelial cells, which was alleviated by sgp130 or AG490. IL-6 trans-signaling could induce the phosphorylation of STAT3, which is recruited to the cellular nucleus of Met-5A cells.
Answer: The present study might provide evidence that high glucose up-regulates IL-6 synthesis in Met-5A cells, to some extent, depending on its osmolality and that IL-6 trans-signaling could induce VEGF synthesis partly dependent on the JAK/STAT3 pathway. This article is protected by copyright. All rights reserved.

Does interleukin-6 trans-signaling induce VEGF synthesis partly via Janus kinases-STAT3 pathway in human mesothelial cells?