TASK DEFINITION: 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.
PROBLEM: Context: Human induced pluripotent stem cells (iPSCs) play an important role in disease modeling and drug testing. However, the current methods are time-consuming and lack an isogenic control.', 'This study sought to establish an efficient technology to generate human PSC-based disease models with isogenic control.', 'The ion channel genes KCNQ1 and KCNH2 with dominant negative mutations causing long QT syndrome types 1 and 2, respectively, were stably integrated into a safe harbor AAVS1 locus using zinc finger nuclease technology.', 'Patch-clamp recording revealed that the edited iPSC-derived cardiomyocytes (iPSC-CMs) displayed characteristic long QT syndrome phenotype and significant prolongation of the action potential duration compared with the unedited control cells. Finally, addition of nifedipine (L-type calcium channel blocker) or pinacidil (KATP-channel opener) shortened the action potential duration of iPSC-CMs, confirming the validity of isogenic iPSC lines for drug testing in the future.
Answer: Our study demonstrates that iPSC-CM-based disease models can be rapidly generated by overexpression of dominant negative gene mutants.

SOLUTION: Does genome editing of isogenic human induced pluripotent stem cells recapitulate long QT phenotype for drug testing?

PROBLEM: Context: The clinical value of oesophageal histology in non-complicated gastro-oesophageal reflux disease (GORD) is controversial. Our aim was to explore the role of histology in preoperative diagnosis and postoperative follow-up in GORD.', 'From 40 patients 2 histopathologists graded and scored 191 oesophageal biopsies in a blinded manner to evaluate inter- and intraobserver variation pre- and postoperatively. Correlation between preoperative histology and objective clinical findings (endoscopy, esophageal 24-hour pH monitoring, and manometry) was calculated as well.', 'Pathologist I interpreted 16 (50%) preoperative biopsies as normal, 5 (16%) with mild, 4 (12.5%) moderate, and 7 (21.9%) severe reflux changes. Pathologist II interpreted 11 (35.5%) preoperative biopsies as normal, 11 (35.5%) with mild, 6 (19.4%) moderate, and 3 (9.7%) severe reflux changes. In preoperative biopsies, interobserver variation was 33.8% and intraobserver variation 9.7%. A positive correlation was detectable between preoperative endoscopic and morphologic findings; no correlation existed between either acid reflux or LES pressure and oesophageal morphology. Normal pH monitoring and fundic wrap were noted postoperatively in all cases. In postoperative histology no significant differences according to pathologist I existed when compared with preoperative changes: 22 normal (69%), 7 mild (22%), 1 moderate (3.1%), and 2 severe (6.3%). Compared to preoperative analysis, pathologist II interpreted 24 (77%, p = 0.001) of the postoperative findings as normal, 1 (3%, p = 0.003) as mild, 4 (12.9%, n.s.) as moderate, and 2 (6.5% n.s.) as severe reflux changes. In postoperative biopsies interobserver variation was 21.1% and intraobserver variation 5.6%.
Answer: The role of oesophageal histology in preoperative diagnosis and postoperative follow-up of GORD may be considered limited.

SOLUTION: Is oesophageal histology in gastro-oesophageal reflux disease of minor pre- and postoperative diagnostic value?

PROBLEM: Context: Gastric Helicobacter pylori (H. pylori) infection and colorectal polyps are more prevalent in African Americans than in the general population. We aimed to investigate whether gastric H. pylori infection is associated with colorectal polyps in African Americans.', 'Medical records of African Americans, 40 years and older (n = 1256) who underwent bidirectional gastrointestinal endoscopy on the same day were reviewed. H. pylori status was assessed by immunohistochemistry on gastric specimens. Colorectal polyps were confirmed by histological examination of colorectal biopsies. A subset of serum samples from healthy and polyp-bearing patients (n = 163) were analyzed by ELISA for anti-H. pylori and anti-CagA antibodies. The crude and adjusted effect of H. pylori on the risk of colorectal adenoma and polyp were computed by logistic regression models.', "The prevalence of colorectal polyps and adenomas were 456 (36%) and 300 (24%) respectively. Colorectal polyps were more prevalent in gastric H. pylori infected than non-infected subjects [43% vs. 34%; Odds Ratio (OR) (95% CI): 1.5 (1.2-1.9), P = 0.001]. Patients with H. pylori-associated chronic active gastritis were at high risk to have adenomas [Unadjusted OR (95% CI): 1.3 (1.0-1.8); P = 0.04]. There was no difference in histopathology, size, or location of polyps with respect to H. pylori status. Gastric H. pylori infection, age, male gender and high risk clinical presentations were independent risk factors for colorectal polyps. Serological testing also revealed a higher prevalence of H. pylori and its toxin Cag-A in polyp patients vs. non polyp patients' sera, although in a non-statistically significant manner.
Answer: This study showed that current gastric H. pylori infection is associated with an increased risk of colorectal polyps in African Americans. Patients with H. pylori induced gastritis may benefit from early screening colonoscopy as a preventative measure for colorectal cancer.

SOLUTION:
Does gastric Helicobacter pylori infection associate with an increased risk of colorectal polyps in African Americans?