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.

Context: To study the effect of Cleistocalyx nervosum extract (CE) on diethylnitrosamine (DEN) and phenobarbital (PB) induced oxidative stress in early stages of rat hepatocarcinogenesis.', 'Male Wistar rats were divided into 4 groups, with Group 1 as a negative control and Group 2 was a positive control receiving DEN injections once a week and PB in drinking water for 6 weeks. Two weeks before DEN initiation and PB treatment, Groups 3 and 4, were fed with 500 and 1000 mg/kg of CEs, respectively, for 8 weeks.', 'A number of GST-P-positive foci, preneoplastic lesions, in the liver were markedly increased in carcinogen administered rats, but was comparatively decreased in rats treated with 1000 mg/kg of CE. The CE reduced malondialdehyde in serum and in the livers of rats treated with DEN and PB. Moreover, CE significantly increased the activities of glutathione peroxidase and catalase in rat liver.
Answer: CE appeared to exert its chemopreventive effects by modulating antioxidant status during DEN and PB induced early stages of hepatocarcinogenesis in rats.
Does cleistocalyx nervosum extract ameliorate chemical-induced oxidative stress in early stages of rat hepatocarcinogenesis?

Context: The use of sedation allows medical procedures to be performed outside the operating room while ensuring patient comfort and a controlled environment to increase the yield of the procedure. There is concern about a higher risk of adverse events with use of sedation in patients with obstructive sleep apnea.', 'We aimed to determine if the presence of obstructive sleep apnea increased the risk of hospitalization and/or health care use after patients received moderate conscious sedation for an elective, ambulatory colonoscopy.', 'We conducted a retrospective case-control database and chart review study. We compared hospital admissions, intensive care unit (ICU) admissions, and emergency room visits at 24 hours, 7 days, and 30 days in patients with obstructive sleep apnea (n\u2009=\u20093,860) and without obstructive sleep apnea (n\u2009=\u20092,374) who had undergone an elective, ambulatory colonoscopy with sedation.', 'We found no significant differences in hospital admissions, ICU admissions, or emergency room visits between the two groups at any time point within the 30 days following the procedures. In a sensitivity analysis in which we compared 827 individuals with polysomnographically confirmed sleep apnea with control subjects, there was still no difference in hospital admissions, ICU admissions, or emergency room visits in the 30 days after receiving sedation for the procedure. Outcomes were not different in individuals with various severities of obstructive sleep apnea.
Answer: The presence of obstructive sleep apnea was not associated with increased early hospital admissions, ICU admissions, or emergency room visits after colonoscopy with sedation.
Is obstructive Sleep Apnea Associated with Higher Health Care Use after Colonoscopy under Conscious Sedation?

Context: To investigate the existence condition of hepatitis B surface antigen(HBsAg) termination codon bias.', 'A total of 174 reference sequences of all kinds of Hepatitis B virus(HBV) genotypes were chosen from GenBank, and compared by BioEdit. Then secondary structure of RNA was constructed and analyzed together.', '(1) There were two types of HBsAg termination codon: TAA and TGA in 174 reference sequences. TAA was in 124 cases (71.26%); and TGA in 50 cases (28.74%). (2) There was codon bias selection in HBsAg termination codon, and it could affect the secondary structure of RNA and amino acid sequence encoding protein.
Answer: HBsAg termination codon bias exists and may be related to RNA structure and the conservation of protein function in the evolutionary progress.

Does [ Hepatitis B surface antigen terminate codon bias selection ]?