instruction:
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.
question:
Context: Postoperative neurologic deficits after thoracic aortic reconstruction vary widely. Our previous study showed that delayed ischemic preconditioning could prevent spinal cord injury caused by occlusion of the descending thoracic aorta in pigs. We investigated early ischemic preconditioning in the same model.', 'Twenty-eight pigs were divided into 4 groups: group 1 (n = 6) underwent a sham operation, group 2 (n = 6) underwent aortic occlusion for 20 minutes, group 3 (n = 8) underwent aortic occlusion for 35 minutes, and group 4 (n = 8) underwent aortic occlusion for 20 minutes and underwent aortic occlusion 80 minutes later without hypotension for 35 minutes. Aortic occlusion was accomplished by using 2 balloon occlusion catheters placed fluoroscopically at T6 to T8 above the diaphragm and at the aortic bifurcation. Neurologic evaluation was performed by an independent observer according to the Tarlov scale (0-4). The lower thoracic and lumbar spinal cords were harvested at 120 hours and examined histologically with hematoxylin-and-eosin stain. Histologic results (number of neurons and grade of inflammation) were scored (0-4) and were similarly analyzed. Statistical analysis was by means of the Kruskal-Wallis test.', 'Group 4 had a better neurologic outcome at 24, 48, and 120 hours in comparison with group 3 (P <.001). The histologic changes were proportional to the neurologic test scores, with the more severe and extensive gray matter damage in animals of group 3 (number of neurons, P <.001; grade of inflammation, P <.001).
Answer: Early ischemic preconditioning without hypotension protects against spinal cord injury after aortic occlusion, as confirmed by using the Tarlov score and histopathology.
answer:
Does early ischemic preconditioning without hypotension prevent spinal cord injury caused by descending thoracic aortic occlusion?


question:
Context: Transcatheter aortic valve implantation (TAVI) without predilatation has fewer procedural steps and thereby potentially fewer complications. This has been demonstrated for the antegrade transapical access; however, whether TAVI can be safely performed without predilatation using the retrograde transfemoral route is unknown.', 'We postulated that TAVI is feasible with a balloon-expandable device without predilatation using the retrograde transfemoral route.', 'Twenty-six consecutive patients with stenosis of the native aortic valve (AV) undergoing transfemoral TAVI with the Edwards SAPIEN XT prosthesis without predilatation were enrolled in this retrospective study and compared with 30 patients treated previously with predilatation.', 'The procedure was successfully performed in all 26 patients, irrespective of the AV area and the extent of AV calcification. At baseline mean AV area, mean AV gradient, and median left ventricular ejection fraction were 0.7 ± 0.2 cm(2) , 36.0 ± 17.3 mm Hg, and 55.0% (interquartile range [IQR], 35.0-60.0], respectively; prior to discharge these values were 1.7 ± 0.3 (P < 0.001), 9.8 ± 6.1 mm Hg (P < 0.001), and 57.5% (IQR, 38.7-60.0) (P = not significant). Postdilatation was required in 3 patients due to aortic regurgitation > 2°; this was reduced by the procedure to < 2° in all cases. Radiation dose and amount of contrast dye were significantly reduced in comparison with the predilatation group. No periprocedural neurological adverse events occurred. Mortality at 30 days was 0%.
Answer: TAVI without predilatation using the transfemoral Edwards SAPIEN XT valve is feasible and safe. Larger studies are required to further evaluate this approach.
answer:
Is transfemoral aortic valve implantation of Edwards SAPIEN XT without predilatation feasible?


question:
Context: The Achilles tendon is one of the most common sites of tendon injury and rupture. One of the early events of wound healing is angiogenesis, in which neovascularization prompts delivery of inflammatory cells and fibroblasts to the wound site. Angiogenesis is controlled by a variety of mitogenic, chemotactic, or inhibitory peptides and lipid factors that act on invading endothelial and smooth muscle cells. One of the most important angiogenic factors is the vascular endothelial cell growth factor (VEGF), a glycosylated protein of 46-48 kDa composed of two disulfide-linked subunits.', 'We therefore investigated the expression of VEGF during healing of artificial lesions of the Achilles tendon in a sheep model by immunohistochemical, biochemical, molecular, and cell biology methods. Two groups were created, the Achilles tendon was tenotomized, and the animals were killed at 3 and 24 weeks. Each group consisted of 6 specimens. Six animals which did not undergo surgery served as controls.', 'VEGF could be immunostained in tenocytes of ruptured but not in normal adult tendons. At microvessels, the receptors VEGFR-1 (flt-1) and VEGFR-2 (KDR) could also be visualized. High VEGF levels in ruptured and negligible levels in normal Achilles tendons could be confirmed and quantified by enzyme-linked immunoassay (ELISA). The highest VEGF concentrations were found in ruptured tendons, whereas the VEGF content in healthy adult tendons was negligible. Interestingly, the VEGF concentration of the original tendon stump was higher after 3 weeks than that of the newly regenerated tendon tissue. However, this difference was not significant (p>0.05). Reverse transcription-polymerase chain reaction (RT-PCR) showed that the splice variants VEGF(120 )and VEGF(164) are expressed at 3 weeks and 24 weeks, respectively.
Answer: These results prove the presence of the splice variants VEGF(120 )and VEGF(164) in ruptured tendons during the healing process. The demonstrated up-regulation of VEGF in intrinsic tenocytes suggests a role for VEGF in mechanisms of angiogenesis and Achilles tendon repair. Further research is needed to evaluate if VEGF might be a possible tool to enhance the process of tendon healing.
answer:

Are the splice variants 120 and 164 of the angiogenic peptide vascular endothelial cell growth factor ( VEGF ) expressed during Achilles tendon healing?