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.
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Question: 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.

Answer: Does purification of polyethylenimine polyplexes highlight the role of free polycations in gene transfer?


Question: Context: We hypothesized that self-reported pad use per day (PPD) after pubovaginal sling (PVS) correlated with postoperative quality of life (QOL) scores.', 'Two hundred fifteen women completed the incontinence impact questionnaire 7 (IIQ-7) and urogenital distress inventory 6 (UDI-6) before PVS and during follow-up. Starting 3 days before a visit, women recorded the number of protective urinary pad changes per day. Analysis of variance and Pearson correlation tests were used to determine if women reporting zero, one, or greater than or equal to two urinary pads per day after PVS had significantly different changes in baseline QOL scores.', 'Over a mean 8.5 months follow-up after PVS, 131, 56, and 28 women reported zero, one, and greater than or equal to two pad changes/day. Each pad group showed progressively less improvement from baseline IIQ-7 and UDI-6 scores after PVS. Change in IIQ-7 and UDI-6 scores negatively correlated with PPD (p < 0.0001).
Answer: Self-reported PPD after PVS reflects patient perception of urinary-specific QOL.

Answer: Does self-reported pad use per day reflect patient quality of life after pubovaginal sling surgery?


Question: Context: Air pollution is a major health challenge worldwide and has previously been strongly associated with adverse reproductive health. This study aimed to examine the association between spontaneous abortion and seasonal variation of air pollutants in Ulaanbaatar, Mongolia.', 'Monthly average O3, SO2, NO2, CO, PM10 and PM2.5 levels were measured at Mongolian Government Air Quality Monitoring stations. The medical records of 1219 women admitted to the hospital due to spontaneous abortion between 2009-2011 were examined retrospectively. Fetal deaths per calendar month from January-December, 2011 were counted and correlated with mean monthly levels of various air pollutants by means of regression analysis.', 'Regression of ambient pollutants against fetal death as a dose-response toxicity curve revealed very strong dose-response correlations for SO2 r\u2009>\u20090.9 (p\u2009<\u20090.001) while similarly strongly significant correlation coefficients were found for NO2 (r\u2009>\u20090.8), CO (r\u2009>\u20090.9), PM10 (r\u2009>\u20090.9) and PM2.5 (r\u2009>\u20090.8), (p\u2009<\u20090.001), indicating a strong correlation between air pollution and decreased fetal wellbeing.
Answer: The present study identified alarmingly strong statistical correlations between ambient air pollutants and spontaneous abortion. Further studies need to be done to examine possible correlations between personal exposure to air pollutants and pregnancy loss.

Answer:
Does seasonal ambient air pollution correlate strongly with spontaneous abortion in Mongolia?