Given a passage, 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]: Stilbenes are plant secondary metabolites that have shown promising and varied biological activities. Stilbenes are presently actively studied for the exploitation of this primary raw material resource, involving the concept of biorefining. Methods for the rapid discovery of new and known stilbene structures from various plant sources are thus keenly sought.', 'To establish a simple and rapid technique of off-line HPLC with a diode-array detector (DAD) and NMR for the unambiguous structural elucidation of stilbene structures in the root bark of Norway spruce [Picea abies (L.) Karst.].', 'The stilbene containing fraction was extracted from the plant bark with an ethanol:water mixture (95:5, v/v) preceded by defatting of hydrophobic compounds with n-hexane using the accelerated solvent extraction technique. A portion of the ethanol-water soluble extract was hydrolysed with β-glucosidase to prepare stilbene aglycones. The extracts were further purified and enriched using a polymeric adsorbent. Stilbene-enriched extracts were directly characterised by off-line HPLC/DAD-NMR in conjunction with HPLC/DAD and HPLC/DAD with electrospray ionisation MS(n).', 'Trans-isorhapontin and trans-astringin were identified as the major, and trans-piceid as a minor, stilbene glucosides of the bark of roots of Picea abies. Not only stilbene glucosides but also the corresponding stilbene aglycones, such as trans-resveratrol, trans-piceatannol and trans-isorhapontigenin, were rapidly identified from the hydrolysed extract. The acquired heteronuclear single-quantum coherence and heteronuclear multiple bond correlation spectra were used to assign the complete carbon NMR chemical shifts of trans-isorhapontin and trans-astringin without the need of acquiring a (13)C-NMR spectrum.
[A]: Do rapid chemical characterisation of stilbenes in the root bark of Norway spruce by off-line HPLC/DAD-NMR?


[Q]: The scope of this work was to study synergism between human papillomavirus (HPV) infection and tobacco in vitro, both known to be independent risk factors for oral cancer.', 'HPV-positive and HPV-negative oral keratinocytes and oral HPV-negative fibroblasts were exposed to smokeless tobacco extract (STE) prepared from the Scandinavian (STE1) and US-type (STE2) snuff. Cell cycle profiles were determined with flow cytometry, and HPV E6/E7 mRNA expression in HPV-positive cells was assayed using RT-qPCR.', 'The exposure of HPV-positive keratinocytes with STE2 increased the number of aneuploid cells from 27% to 80% of which 44% were in S-phase, while none of the diploid cells were in S-phase. The changes after STE1 exposure were less than seen after STE2: from 27% to 31% of which 34% were in S-phase. STE had no effect on HPV16 E6/E7 expression in HPV-positive keratinocytes. In oral spontaneously transformed, HPV-negative keratinocytes, the number of aneuploid cells at G2-M stage increased after STE1 and STE2 exposure from 3% to 9% and 7%, respectively. In HPV-negative oral fibroblasts, the number of cells at G2-M phase increased from 11% to 21% after STE1 and 29% after STE2 exposure.
[A]: Does smokeless tobacco increase aneuploidy in oral HPV16 E6/E7-transformed keratinocytes in vitro?


[Q]: Baseline carbohydrate antigen 19-9 (CA 19-9) is a useful prognostic marker in pancreatic ductal adenocarcinoma (PDA); however, data on the significance of a change in CA 19-9 following neoadjuvant therapy are lacking.', "All patients receiving neoadjuvant therapy for PDA from July 2010 to February 2013 were retrospectively reviewed. Resection rate, R0 resection rate, need for venous resection, and overall survival were correlated to CA 19-9 response. Fisher's exact test, Kaplan-Meier survival analysis, and multivariate analysis using Cox regression were used.", 'A total of 78 patients were studied (21 patients with resectable disease, 40 borderline resectable, and 17 with locally advanced disease). A variety of chemotherapies ± radiation were utilized during the study period. Overall, 56 patients (72 %) had a decrease in CA 19-9 of >50 % with neoadjuvant treatment. In borderline resectable patients, CA 19-9 response of >50 % predicted R0 resection (odds ratio 4.2; p = 0.05). In borderline resectable patients who had an increase in CA 19-9, none of five (0 %) underwent R0 resection compared with 80 % of the remaining cohort (p = 0.001). The complete pathologic response rate was 29 % in patients who had a CA 19-9 response of >90 % versus 0 % in the remaining patients (p < 0.001). A CA 19-9 response of >50 % resulted in improved overall survival (28.0 vs. 11.1 months; p < 0.0001) and was an independent predictor of survival (hazard ratio 0.26; 95 % CI 0.13-0.55; p < 0.0001).
[A]:
Is serum CA 19-9 response to neoadjuvant therapy associated with outcome in pancreatic adenocarcinoma?