TASK DEFINITION: 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.
PROBLEM: Context: Associations between multidrug resistance and the Mycobacterium tuberculosis Beijing genotype have been described mainly in populations with poor tuberculosis (TB) control such as prisons and inner cities, and may reflect shared risk factors rather than a biological association.', 'To study the association between genotype and drug resistance among TB patients in a population with adequate TB control.', 'Three rural districts in Vietnam. The study was performed at the Pham Ngoc Thach Tuberculosis and Lung Disease Hospital, Ho Chi Minh City, and the Tien Giang Provincial Tuberculosis and Lung Disease Hospital, My Tho, Vietnam.', 'Pretreatment sputum specimens were collected for culture, drug susceptibility testing and spoligotyping of all sputum smear-positive pulmonary TB patients consecutively diagnosed over a 3-year period.', 'Beijing genotype infections were observed in 614 of 1744 (35%) patients. Beijing strains were more common among female (adjusted odds ratio [aOR] 1.4, P = 0.005), young (aOR 2.8, P < 0.001) and previously treated patients (aOR 2.4, P < 0.001). The Beijing genotype was associated with any resistance (aOR 3.7, P < 0.001) and multidrug resistance (aOR 6.8, P < 0.001) among new patients, and with any resistance (aOR 2.7, P = 0.005) but not with multidrug resistance (aOR 1.4, P = 0.545) among previously treated patients.
Answer: In Vietnam, Beijing genotype is associated with young age and in new patients with multidrug resistance despite adequate TB control, suggesting a biological association. This potentially undermines the effectiveness of TB control in countries where Beijing genotype infections are common.

SOLUTION: Is the Beijing genotype associated with young age and multidrug-resistant tuberculosis in rural Vietnam?

PROBLEM: 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.

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

PROBLEM: Context: To demonstrate a method to extract the meaningful biologic information from (111)In-radiolabeled capromab pendetide (ProstaScint) SPECT scans for use in radiation therapy treatment planning by removing that component of the (111)In SPECT images associated with normal structures.', 'We examined 20 of more than 80 patients who underwent simultaneous (99m)Tc/(111)In SPECT scans, which were subsequently registered to the corresponding CT/MRI scans.A thresholding algorithm was used to identify (99m)Tc uptake associated with blood vessels and CT electron density associated with bone marrow. Corresponding voxels were removed from the (111)In image set.', 'No single threshold value was found to be associated with the (99m)Tc uptake that corresponded to the blood vessels. Intensity values were normalized to a global maximum and, as such, were dependent upon the quantity of (99m)Tc pooled in the bladder. The reduced ProstaScint volume sets were segmented by use of a thresholding feature of the planning system and superimposed on the CT/MRI scans.
Answer: ProstaScint images are now closer to becoming a biologically and therapeutically useful and accurate image set. After known sources of normal intensity are stripped away, the remaining areas that demonstrate uptake may be segmented and superimposed on the treatment-planning CT/MRI volume.

SOLUTION:
Does procedure for unmasking localization information from ProstaScint scan for prostate radiation therapy treatment planning?