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.

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

A: 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.
****
Q: Context: This study investigated whether a 7-week yoga intervention could improve physical function, perceived stress, and mental/emotional wellness in elderly participants.', '8 participants (66.5\xa0±\xa00.3 years) attended 2 60-min Hatha yoga sessions/week for 7 weeks, and performed pre- and post-intervention assessments. Balance was assessed using a 5-test battery. Flexibility was measured by sit-and-reach and shoulder flexibility tests. Functional mobility tests included 8-ft up-and-go, 5 chair stands, and 4-m walk. Participants completed SF-12, exhaustion level, and Perceived Stress Scale (PSS) questionnaires.', 'SF-12 Mental Component Summary scores, exhaustion levels, and PSS scores improved post-intervention. No differences were found for physical function measures.\Question: Does yoga reduce perceived stress and exhaustion levels in healthy elderly individuals?

A: Yoga participation can improve mental/emotional wellness, exhaustion levels, and stress levels in elderly individuals, even without measurable improvements in physical function. Clinicians and health practitioners who work with the elderly should consider yoga as a potential therapeutic modality for improving important aspects of quality of life in this population.
****
Q: Context: Guanidinoacetic acid (GAA) is an experimental dietary additive that might act as a creatine source in tissues with high-energy requirements. In this case study, we evaluated brain levels of creatine in white matter, gray matter, cerebellum, and thalamus during 8\xa0wk oral GAA administration in five healthy men and monitored the prevalence and severity of side effects of the intervention.', 'Volunteers were supplemented daily with 36\xa0mg/kg body weight (BW) of GAA for the first 4\xa0wk of the intervention; afterward GAA dosage was titrated ≤60\xa0mg/kg BW of GAA daily. At baseline, 4, and 8\xa0wk, the participants underwent brain magnetic resonance spectroscopy, clinical chemistry studies, and open-ended questionnaire for side-effect prevalence and severity.', 'Brain creatine levels increased in similar fashion in cerebellum, and white and gray matter after GAA supplementation, with an initial increase of 10.7% reported after 4\xa0wk, and additional upsurge (7.7%) from the weeks 4 to 8 follow-up (P\xa0<\xa00.05). Thalamus creatine levels decreased after 4\xa0wk for 6.5% (P\xa0=\xa00.02), and increased nonsignificantly after 8\xa0wk for 8% (P\xa0=\xa00.09). GAA induced an increase in N-acetylaspartate levels at 8-wk follow-up in all brain areas evaluated (P\xa0<\xa00.05). No participants reported any neurologic adverse event (e.g., seizures, tingling, convulsions) during the intervention.\Question: Does dietary guanidinoacetic acid increase brain creatine levels in healthy men?

A:
Supplemental GAA led to a region-dependent increase of the creatine pool in the human brain. This might be relevant for restoring cellular bioenergetics in disorders characterized by low brain creatine and functional enzymatic machinery for creatine synthesis, including neurodegenerative diseases, brain tumors, or cerebrovascular disease.
****