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.

Example Input: Context: After formation of the linear heart tube a chamber-specific program of gene expression becomes active that underlies the formation of the chamber myocardium. To assess whether this program is recapitulated in in vitro differentiated embryonic stem cells, we performed qualitative and quantitative analyses of cardiogenesis in vivo and in vitro.', 'Gene expression profiles were made by in situ hybridisation and real-time PCR and electrophysiological profiles by patch clamp analyses of cardiomyocytes derived from time series of differentiating HM1 mouse embryonic stem cells and from embryonic and adult mouse hearts.', 'In embryoid bodies the in situ patterns of expression of alpha-myosin heavy chain, myosin light chain 2a and sarcoendoplasmic reticulum calcium ATPase 2a were similar to that of the heart muscle-specific marker gene cardiac troponin I. Myosin light chain 2v was expressed in part of the cardiac troponin I-expressing area, indicating heterogeneity within the cardiac cell population. Atrial natriuretic factor expression, indicative of the chamber-type program, could only very occasionally be detected by in situ hybridisation. Quantitative reverse transcriptase PCR showed that all cardiac genes, most notably atrial natriuretic factor, were expressed at relatively low levels, similar to those in embryonic hearts at embryonic day 8.75-9. Analysis of the electrophysiological characteristics of embryonic stem cell-derived cardiomyocytes showed an increase of the upstroke velocity and a shorter duration of the action potential during prolonged differentiation in vitro. When embryonic mouse heart compartments of embryonic day 12.5 were used as a reference, the electrophysiological characteristics of a substantial part of the embryonic stem cell-derived cardiomyocytes were most reminiscent to those observed in the embryonic outflow tract.
Answer: Together, these data suggest that most cardiomyocytes acquired by differentiation of embryonic stem cells maintain a phenotype reminiscent of that of the cardiomyocytes of the primary heart tube, and hardly any myocytes develop a chamber myocardial phenotype.
Example Output: Do cardiomyocytes derived from embryonic stem cells resemble cardiomyocytes of the embryonic heart tube?

Example Input: Context: The aim of this study was to investigate the association of lipoprotein(a) [Lp(a)] with the severity of coronary heart disease (CHD) in Han Chinese people.', 'Six hundred and seventy-nine patients with angiographically defined CHD were enrolled in this cross-sectional study. Fasting lipids were measured, and the severity of CHD was quantitatively assessed for each patient according to the number of stenotic coronary branches and the Gensini scoring system.', 'The levels of Lp(a), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), and apolipoprotein (apo) B100 increased, while high-density lipoprotein cholesterol (HDL-C) and apoAI decreased significantly with the number of stenotic vessels. The levels of Lp(a) increased and HDL-C and apoAI decreased significantly with the Gensini scores. The logistic regression analyses showed that Lp(a) and HDL-C were independently associated with the number of stenotic coronary vessels after adjusting for age, weight, body mass index, sex, smoking, alcohol consumption, hypertension, diabetes, triglycerides, TC, LDL-C, VLDL-C, apoAI, and apoB100. However, only Lp(a) was independently associated with the Gensini scores after adjustment.
Answer: Our data indicate that Lp(a) might be a useful marker in predicting the severity of coronary heart disease.
Example Output: Are plasma lipoprotein ( a ) levels associated with the severity of coronaryheart disease in Han Chinese people?

Example Input: Context: For years, Uniform Resource Locator (URL) decay or "link rot" has been a growing concern in the field of biomedical sciences. This paper addresses this issue by examining the status of the URLs published in MEDLINE abstracts, establishing current availability and estimating URL decay in these records from 1994 to 2006. We also reviewed the information provided by the URL to determine if the context that the author cited in writing the paper is the same information presently available in the URL. Lastly, with all the documented recommended methods to preserve URL links, we determined which among them have gained acceptance among authors and publishers.', 'MEDLINE records from 1994 to 2006 from the National Library of Medicine in Extensible Mark-up Language (XML) format were processed yielding 10,208 URL addresses. These were accessed once daily at random times for 30 days. Titles and abstracts were also searched for the presence of archival tools such as WebCite, Persistent URL (PURL) and Digital Object Identifier (DOI).', 'Results showed that the average URL length ranged from 13 to 425 characters with a mean length of 35 characters [Standard Deviation (SD) = 13.51; 95% confidence interval (CI) 13.25 to 13.77]. The most common top-level domains were ".org" and ".edu", each with 34%. About 81% of the URL pool was available 90% to 100% of the time, but only 78% of these contained the actual information mentioned in the MEDLINE record. "Dead" URLs constituted 16% of the total. Finally, a survey of archival tool usage showed that since its introduction in 1998, only 519 of all abstracts reviewed had incorporated DOI addresses in their MEDLINE abstracts.
Answer: URL persistence parallels previous studies which showed approximately 81% general availability during the 1-month study period. As peer-reviewed literature remains to be the main source of information in biomedicine, we need to ensure the accuracy and preservation of these links.
Example Output:
Do an update on Uniform Resource Locator ( URL ) decay in MEDLINE abstracts and measures for its mitigation?