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.

Ex Input:
Context: Completeness of cytoreduction is a significant predictor of long-term outcome after cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Imaging has limited sensitivity to identify peritoneal metastases and therefore predict whether complete cytoreduction is possible. We reviewed our experience using laparoscopy to determine candidates for complete cytoreduction and HIPEC.', 'This single-center, retrospective study examined patients from 2007 to 2014 who underwent laparoscopy to determine complete cytoreduction (CC-0/1)/HIPEC candidacy. Preoperative, intraoperative, and postoperative data were collected.', 'A total of 145 laparoscopies were performed on 141 patients, 72 (51.1%) of whom were female, with a median age of 53years (range 20-79). The primary site was appendiceal in 67 (47.5%) patients, colorectal in 43 (30.5%), mesothelioma in 17 (12.1%), unknown in 9 (6.4%), small bowel in 3 (2.1%), gastric in 1, and ovarian in 1 (0.7% each). Overall, 115 (81.6%) patients had prior abdominal surgery, 111 (76.6%) had evidence of disease on imaging, and 117 (80.7%) underwent prior chemotherapy, with a median of 5.9weeks between the last treatment and laparoscopy (0.9-498.9weeks). Four (2.8%) intraoperative complications were observed (one liver laceration, two enterotomies, and one air embolus), and nine (6.2%) postoperative complications [four (2.8%) Clavien grade (CG) I, three (2.8%) CG II, one (0.7%) CG III (return to operating room) and one (0.7%) CG IV (transient ischemic attack)]. Forty-eight patients deemed candidates by laparoscopy underwent CRS/HIPEC (positive predictive value 82.8%).
Answer: Diagnostic laparoscopy is a safe, feasible, and accurate staging tool in patients with suspected peritoneal metastases being considered for CRS.

Ex Output:
Is laparoscopy Safe and Accurate to Evaluate Peritoneal Surface Metastasis Prior to Cytoreductive Surgery?

Ex Input:
Context: Nonviral vectors based on polyethylenimine (PEI) usually contain an excess of PEI that is not complexed to DNA. Since unbound PEI contributes to cellular and systemic toxicity, purification of polyplexes from unbound PEI is desirable.', 'Size exclusion chromatography (SEC) was used to purify PEI polyplexes of free PEI. Transfection properties of purified polyplexes and the effect of free PEI on gene delivery were studied in vitro and in vivo after systemic application into mice.', 'SEC did not change the size and zeta-potential of polyplexes. Independent of the amount of PEI used for complex formation, purified PEI polyplexes had the same final PEI nitrogen/DNA phosphate ratio of 2.5. Notably, purified PEI polyplexes demonstrated low cellular and systemic toxicity. High transfection efficiency was achieved with purified polyplexes at high DNA concentrations (8-15 microg/ml). At low DNA concentrations (2-4 microg/ml) gene transfer with purified particles was less efficient than with polyplexes containing free PEI both in vitro and in vivo. Mechanistic studies showed that free PEI partly blocked cellular association of DNA complexes but was essential for the following intracellular gene delivery. Adding free PEI to cells treated with purified particles with a delay of up to 4 h resulted in significantly enhanced transfection efficiency compared with non-purified particles or purified particles without free PEI.
Answer: This study presents an efficient method to remove free PEI from PEI polyplexes by SEC. Our results from transfection experiments demonstrate that free PEI substantially contributes to efficient gene expression but also mediates toxic effects in a dose-dependent manner. Purified polyplexes without free PEI have to be applied at increased concentrations to achieve high transfection levels, but exhibit a greatly improved toxicity profile.

Ex Output:
Does purification of polyethylenimine polyplexes highlight the role of free polycations in gene transfer?

Ex Input:
Context: To explore the protective effect of the Phyllanthus Urinaria (PU) extract on the N-cadherin expression in the testicular tissues disrupted by nitrogen mustard (HN2) in vivo.', 'HN2 was intraperitoneally injected into male KM mice at the dose of 5 mg/kg to make reproductive toxicity models, and at the same time PU was administered for intervention at the dose of 125 mg/kg, 250 mg/kg and 500 mg/kg. N-cadherin distribution, mRNA and protein expression in the testicular tissues were detected by immunohistochemistry, RT-PCR and Western blotting.', 'N-cadherin was mainly distributed in the membrane and cytoplasm of Sertoli cells at the basement of seminiferous epithelia, Leydig cells and peritubular cells, scarcely expressed in the basement of seminiferous epithelia and peritubular cells after HN2 administration. The expressions of mRNA and proteins of N-cadherin were significantly elevated with the increased dose of PU (P < 0.01). Compared with the normal control, the distribution and expression of N-cadherin showed no significant differences in either the high-dose PU group or the HN2 with high-dose PU intervention group (P > 0.05).
Answer: The PU extract can effectively promote the N-cadherin expression in the testis tissues disrupted by HN2.

Ex Output:
Does [ Phyllanthus urinaria extract promote N-cadherin expression in nitrogen mustard-disrupted testicular tissues in vivo ]?