TASK DEFINITION: In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
PROBLEM: 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.\Question: Is over expression of the selectable marker blasticidin S deaminase gene toxic to human keratinocytes and murine BALB/MK cells?

SOLUTION: 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.

PROBLEM: Context: Intravenous tissue-type plasminogen activator (tPA) is a proven treatment for acute ischemic stroke, but there has been limited evaluation among patients aged ≥90 years.', 'We analyzed data from the Get With The Guidelines-Stroke national quality improvement registry from January 2009 to April 2013. Frequency, determinants, and outcomes of tPA use were compared among patients aged ≥90 and 3 younger age groups (18-64, 65-79, and 80-89 years).', 'Among 35\u2009708 patients from 1178 sites who arrived within 2 hours of time last known well and received tPA, 2585 (7.2%) were ≥90 years. Compared with younger patients, the rate of tPA use among patients without a documented contraindication was lower among patients aged ≥90 years (67.4% versus 84.1% in 18-89-year olds; P<0.0001). Discharge outcomes among individuals aged ≥90 years included discharge to home or acute rehabilitation in 31.4%, independent ambulation at discharge in 13.4%, symptomatic hemorrhage in 6.1%, and in-hospital mortality or hospice discharge in 36.4%. On multivariable analysis, good functional outcomes generally occurred less often and mortality more often among patients aged ≥90 years. The risk of symptomatic hemorrhage was increased compared with patients <65 years but was not significantly different than the risk in 66- to 89-year olds.\Question: Do use and Outcomes of Intravenous Thrombolysis for Acute Ischemic Stroke in Patients ≥90 Years of Age?

SOLUTION: The use of intravenous tPA among those aged ≥90 years is lower than in younger patients. When fibrinolytic therapy is used, the risk of symptomatic hemorrhage is not higher than in 66- to 89-year olds; however, mortality is higher and functional outcomes are lower.

PROBLEM: Context: Reactive oxygen species have been implicated as signaling molecules modulating the activity of redox-sensitive transcription factors such as nuclear factor kappa B (NF-kappaB). Recently, the transcription factor hypoxia-inducible factor-1 (HIF-1), known to mediate gene expression by hypoxia, has been found to be also activated by nonhypoxic factors in a redox-sensitive manner. We therefore aimed to elucidate the link between these 2 important redox-sensitive transcription factors.', 'In pulmonary artery smooth muscle cells, reactive oxygen species generated either by exogenous H2O2 or by a NOX4-containing NADPH oxidase stimulated by thrombin activated or induced NF-kappaB and HIF-1alpha. The reactive oxygen species-mediated HIF-1alpha induction occurred on the transcriptional level and was dependent on NF-kappaB. Transfection experiments with wild-type or mutant HIF-1alpha promoter constructs revealed the presence of a yet unidentified NF-kappaB binding element. Gel shift analyses and chromatin immunoprecipitation verified binding of NF-kappaB to this site. Furthermore, reactive oxygen species enhanced expression of plasminogen activator inhibitor-1, which was prevented by dominant-negative IkappaB or mutation of the HIF-1 binding site within the plasminogen activator inhibitor-1 promoter.\Question: Do reactive oxygen species activate the HIF-1alpha promoter via a functional NFkappaB site?

SOLUTION:
These findings show for the first time to our knowledge that reactive oxygen species directly link HIF-1alpha and NF-kappaB, implicating an important pathophysiological role of this novel pathway in disorders associated with elevated levels of reactive oxygen species.