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.

Input: Consider Input: To compare the safety and success of a retrograde approach using a microcatheter vs. a sheath in the treatment of superficial femoral artery (SFA) chronic total occlusions (CTOs).', 'From April 2007 to December 2012, 188 consecutive patients underwent EVT for 229 de novo SFA CTOs using the retrograde approach in 68 patients (35 men; mean age 72 years). This cohort was divided into cases performed with a 4-F or 6-F sheath (n=28, 36 limbs) and those with a 2.1-F microcatheter (n=35, 49 limbs). The primary outcomes were mean time to hemostasis and number of intra- and postoperative puncture site complications, as well as the success of popliteal artery puncture, lesion crossing, and reperfusion.', 'There were no significant differences between two groups in baseline characteristics. PA puncture was successful in all limbs, and the success in crossing the lesion with the wire was not significantly different (91.9% in the sheath group vs. 89.8% in the microcatheter group). Mean time to hemostasis was 8.9±8.8 minutes in the microcatheter group vs. 47.7±13 minutes in the sheath group (p<0.0001). There was a significant difference in intraoperative and postoperative complications (22.2% in the sheath group vs. 2.0% in the microcatheter group, p=0.002).

Output: Is a sheathless retrograde approach via the popliteal artery useful and safe for treating chronic total occlusions in the superficial femoral artery?


Input: Consider Input: The human immunodeficiency virus Vif protein overcomes the inhibitory activity of the APOBEC3G cytidine deaminase by prohibiting its packaging into virions. Inhibition of APOBEC3G encapsidation is paralleled by a reduction of its intracellular level presumably caused by the Vif-induced proteasome-dependent degradation of APOBEC3G.', 'In this report we employed confocal microscopy to study the effects of Vif on the expression of APOBEC3G on a single cell level. HeLa cells dually transfected with Vif and APOBEC3G expression vectors revealed efficient co-expression of the two proteins. Under optimal staining conditions approximately 80% of the transfected cells scored double-positive for Vif and APOBEC3G. However, the proportion of double-positive cells observed in identical cultures varied dependent on the fixation protocol and on the choice of antibodies used ranging from as low as 40% to as high as 80% of transfected cells. Importantly, single-positive cells expressing either Vif or APOBEC3G were observed both with wild type Vif and a biologically inactive Vif variant. Thus, the lack of APOBEC3G in some Vif-expressing cells cannot be attributed to Vif-induced degradation of APOBEC3G. These findings are consistent with our results from immunoblot analyses that revealed only moderate effects of Vif on the APOBEC3G steady state levels. Of note, viruses produced under such conditions were fully infectious demonstrating that the Vif protein used in our analyses was both functional and expressed at saturating levels.

Output: Does production of infectious human immunodeficiency virus type 1 require depletion of APOBEC3G from virus-producing cells?


Input: Consider Input: Nondiagnostic fine-needle aspiration biopsy (ND-FNAB) of the thyroid leads to unnecessary thyroidectomy. The aims of this study were as follows: (1) to determine the risk of malignancy in ND-FNABs, and (2) to evaluate factors that may identify patients at risk for a ND-FNAB.', 'A total of 241 patients who underwent FNAB and thyroidectomy were evaluated for factors associated with a ND-FNAB.', 'A total of 215 women and 26 men underwent FNAB and thyroidectomy. ND-FNAs occurred in 51 of 241 (21%) patients. Ultrasound guidance did not reduce the likelihood of a ND biopsy. Patients with nodules greater than 3 cm had more ND-FNAs. Twenty-one of 51 with a ND biopsy underwent a repeat FNAB. Repeat FNAB was ND in 29% of patients. There was malignant disease in 7 of 51 (14%) with a ND-FNAB. Patient age, sex, thyroid function, gland size, multiple nodules, and final pathology were not related to a ND-FNAB (P > .05).


Output: Are nondiagnostic thyroid fine-needle aspiration biopsies no longer a dilemma?