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.

Q: Context: Minimal residual disease (MRD) is defined as the presence of sub-microscopic levels of leukaemia. Measurement of MRD from bone marrow at the end of induction chemotherapy (day 28) for childhood acute lymphoblastic leukaemia (ALL) can highlight a large group of patients (>40%) with an excellent (>90%) short-term event-free survival (EFS). However, follow-up in recent published trials is relatively short, raising concerns about using this result to infer the safety of further therapy reduction in the future.', 'We examined MRD data on 225 patients treated on one of three UKALL trials between 1997 and 2003 to assess the long-term (>10\u2005years follow-up) outcome of those patients who had low-risk MRD (<0.01%) at day 28.', 'Our pilot data define a cohort of 53% of children with MRD <0.01% at day 28 who have an EFS of 91% and long-term overall survival of 97%. Of 120 patients with day-28 MRD <0.01% and extended follow-up, there was one death due to treatment-related toxicity, one infectious death while in complete remission, and four relapse deaths.
Answer: The excellent outcome for childhood ALL in patients with MRD <0.01% after induction chemotherapy is sustained for more than 10 years from diagnosis. This supports the potential exploration of further reduction of therapy in this group, in an attempt to reduce treatment-related mortality and late effects.

A: Is excellent outcome of minimal residual disease-defined low-risk patients sustained with more than 10 years follow-up : results of UK paediatric acute lymphoblastic leukaemia trials 1997-2003?
****
Q: 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.

A: Does purification of polyethylenimine polyplexes highlight the role of free polycations in gene transfer?
****
Q: Context: Recently, there has been increasing concern about adverse health effects of exposure to desert dust events. However, the association between dust and the incidence of ischemic heart diseases is unknown. The aim of the present study was to elucidate whether Asian dust (AD), a windblown sand dust originating from mineral soil in China and Mongolia, is associated with the incidence of acute myocardial infarction (AMI).', 'We investigated the data regarding hospitalization because of AMI among 3068 consecutive patients from 4 AMI centers in Fukuoka, Japan, and data for AD from April 2003 to December 2010. We applied a time-stratified case-crossover design to examine the association between AD and the incidence of AMI. Using a conditional logistic regression analysis, we estimated the odds ratios of AMI associated with AD after controlling for ambient temperature and relative humidity. The occurrence of AD events 0 to 4 days before the day of admission was significantly associated with the incidence of AMI. In particular, the occurrence of AD 4 days before admission was significantly associated with the onset of AMI.
Answer: These data suggest that exposure to AD a few days before symptom onset is associated with the incidence of AMI.

A:
Is desert dust a risk factor for the incidence of acute myocardial infarction in Western Japan?
****