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: Aggrecanase cleavage at the 392Glu-393Ala bond in the interglobular domain (IGD) of aggrecan, releasing N-terminal 393ARGS fragments, is an early key event in arthritis and joint injuries. Here, we use a quantitative immunoassay of aggrecan ARGS neoepitope fragments in human synovial fluid to determine if this cleavage-site specific method better identifies joint pathology than previously available less specific aggrecan assays.', 'Synovial fluid (SF) from 26 people with healthy knees (reference) and 269 patients were analyzed in a cross-sectional study. Patient groups were acute inflammatory arthritis, acute knee injury, chronic knee injury and knee osteoarthritis (OA). Aggrecan ARGS fragments were assayed by ELISA using the monoclonal antibody OA-1. Total aggrecan content was analyzed by an ELISA using the monoclonal antibody 1-F21, and sulfated glycosaminoglycan by Alcian blue precipitation.', 'Aggrecan ARGS fragment concentrations in all groups differed from the reference group (P < 0.001). The acute inflammatory arthritis group had the highest median level, 177-fold greater than that of the reference group. Median levels (in pmol ARGS/ml SF) were: reference 0.5, acute inflammatory arthritis 88.5, acute knee injury 53.9, chronic knee injury 0.5 and OA 4.6. In contrast, aggrecan and sulfated glycosaminoglycan concentrations varied much less between groups, and only acute inflammatory arthritis and acute knee injury were found to have a two-fold increase in median levels compared to the reference.
Answer: Levels of aggrecan ARGS fragments in human synovial fluid are increased in human arthritis, OA and after knee injury, likely reflecting an enhanced cleavage at the 392Glu-393Ala bond in the IGD by aggrecanase. An assay that specifically quantified these fragments better distinguished samples from joints with pathology than assays monitoring aggrecan or glycosaminoglycan concentrations. The newly developed ARGS fragment assay can be used to monitor aggrecanase activity in human joint disease and experimental models.

A: Is synovial fluid level of aggrecan ARGS fragments a more sensitive marker of joint disease than glycosaminoglycan or aggrecan levels : a cross-sectional study?
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Q: Context: Lung transplantation is a viable option for patients with cystic fibrosis. The current strategy of selection, based on spirometry and deterioration of quality of life, results in a high mortality on the waiting list. We reviewed the case histories of patients with cystic fibrosis accepted for lung transplantation to ascertain whether pulmonary hemodynamics could contribute to predict life expectancy.', 'Forty-five patients with cystic fibrosis were accepted: 11 died on the waiting list (group I), 24 underwent transplantation (group II), and 10 are still waiting (group III). During evaluation we recorded spirometry, oxygen requirement, ratio of arterial oxygen tension to inspired oxygen fraction (PaO (2)/FIO (2)), arterial carbon dioxide tension (PaCO (2)), 6-minute walk test results, right ventricular ejection fraction, echocardiography, and pulmonary hemodynamics. We compared data from group I, II, and III patients. A comparison was also made within group II between the data collected at the time of evaluation and at the time of transplantation to quantify the deterioration during the waiting time.', 'The waiting time, spirometry, 6-minute walk test results, and right ventricular ejection fraction did not differ among the three groups. A statistically significant difference was found for PaO (2)/FIO (2), PaCO (2), mean pulmonary artery pressure, cardiac index, pulmonary arterial wedge pressure, and intrapulmonary shunt between groups I and II. Groups I and III showed statistically significant differences for mean pulmonary artery pressure, PaO (2)/FIO (2), and systemic vascular resistance indexed. No differences were observed between groups II and III. The comparison within group II showed a significant deterioration of pulmonary hemodynamics during the waiting time.
Answer: Pulmonary hemodynamics are worst in patients dying on the waiting list and deteriorate significantly during the waiting time. They may thus contribute to establish priority for lung transplantation in patients with cystic fibrosis.

A: Do pulmonary hemodynamics contribute to indicate priority for lung transplantation in patients with cystic fibrosis?
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Q: Context: The blasticidin S resistance gene (bsr) is a selectable marker used for gene transfer experiments. The bsr gene encodes for blasticidin S (BS) deaminase, which has a specific activity upon BS. Therefore, its expression is supposed to be harmless in cells. The work reported on herein consisted of experiments to verify a possible toxicity of bsr on mammalian cells, which include several cell lines and primary cultures.', 'Murine keratinocyte BALB/MK and human primary keratinocyte cells transduced with the retroviral vector LBmSN, which has an improved expression system of bsr, namely bsrm, died in five days after the transduction. Meanwhile the control vector LBSN, which expresses bsr, did not provoke cell death. The lethal activity of bsrm was observed only in human keratinocytes and BALB/MK cells among the cell types tested here. Death appears to be mediated by a factor, which is secreted by the BALB/MK transduced cells.
Answer: By our study we demonstrated that the expression of bsrm gene is toxic to human keratinocytes and BALB/MK cells. It is likely over expression of BS deaminase gene is responsible for the death.

A:
Is over expression of the selectable marker blasticidin S deaminase gene toxic to human keratinocytes and murine BALB/MK cells?
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