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: The etiology of reduced left ventricular (LV) ejection fraction after exercise, without obstructive coronary artery disease or other established causes, is unclear. The aims of this study were to determine whether patients undergoing treadmill stress echocardiography with this abnormal LV contractile response to exercise (LVCRE) without established causes have resting LV long-axis dysfunction or microvascular dysfunction and to determine associations with this abnormal LVCRE.', 'Of 5,275 consecutive patients undergoing treadmill stress echocardiography, 1,134 underwent cardiac computed tomography angiography or invasive angiography. Having excluded patients with obstructive coronary artery disease, hypertensive response, submaximal heart rate response, resting LV ejection fraction < 50%, and valvular disease, 110 with "abnormal LVCRE" and 212 with "normal LVCRE" were analyzed. Resting mitral annular velocities were measured to assess LV long-axis function. Myocardial blush grade and corrected Thrombolysis In Myocardial Infarction frame count were determined angiographically to assess microvascular function.', "Comparing normal LVCRE with abnormal LVCRE, age (mean, 59.7 ± 11.1 vs 61.4 ± 10.0 years), hypertension (53% vs 55%), diabetes (16% vs 20%), and body mass index (mean, 29.1 ± 5.4 vs 29.5 ± 6.4 kg/m(2)) were similar (P > .05). Abnormal LVCRE had reduced resting LV long-axis function with lower septal (mean, 6.1 ± 1.9 vs 7.7 ± 2.2 cm/sec) and lateral (mean, 8.1 ± 2.9 vs 10.4 ± 3.0 cm/sec) e' velocities (P < .001) and larger resting left atrial volumes (mean, 37.3 ± 10.1 vs 31.1 ± 7.2 mL/m(2), P < .001). On multivariate analysis, female gender (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.15-1.99; P < .001), exaggerated chronotropic response (OR, 1.49; 95% CI, 1.09-2.05; P < .001), resting left atrial volume (OR, 2.38; 95% CI, 1.63-3.47; P < .001), and resting lateral e' velocity (OR, 1.70; 95% CI, 1.22-2.49; P = .003) were associated with abnormal LVCRE, but not myocardial blush grade or corrected Thrombolysis In Myocardial Infarction frame count.
Answer: An abnormal LVCRE in the absence of established causes is associated with resting LV long-axis dysfunction and is usually seen in women.

SOLUTION: Is abnormal left ventricular contractile response to exercise in the absence of obstructive coronary artery disease associated with resting left ventricular long-axis dysfunction?

PROBLEM: Context: The normal anterior translation of the articular surface of the distal humerus with respect to the humeral diaphysis facilitates elbow flexion. We hypothesize that there is a correlation between anterior translation of the distal humeral articular surface and flexion after open reduction and internal fixation (ORIF) of a fracture of the distal humerus.', 'Two independent observers evaluated 141 lateral radiographs of patients more than 6 months after fracture of the distal humerus and 155 lateral radiographs of patients without injury of the distal humerus. The distance between the most anterior point of the distal humerus articular surface, perpendicular to the humeral shaft, from the anterior border of the distal part of the humeral diaphysis, was measured on lateral radiographs as a percentage of the width of the humeral shaft.', 'The technique of measuring anterior translation of the distal humeral articular surface had good intra- and interobserver reliability. The most anterior point of the distal humeral articular surface lies an average of 11.7 mm (range, 6.8 to 17.0 mm) in front of the most anterior border of the humeral shaft in normal distal humeri, which represents 62% of the humeral shaft diameter (range, 33% to 91%). There was a limited but significant correlation between flexion and anterior translation as a percentage of the humeral shaft diameter in distal humeri after fracture that was maintained in multivariable statistical models.
Answer: Using a reproducible technique for measuring anterior translation of the distal humerus, there was a correlation between anterior translation of the distal humeral articular surface and elbow flexion after ORIF. Although the weakness of the correlation emphasizes that limitation of elbow flexion after ORIF of a distal humerus fracture is multifactorial, reduced anterior translation of the distal humeral articular surface might be a contributing factor.

SOLUTION: Is loss of anterior translation of the distal humeral articular surface associated with decreased elbow flexion?

PROBLEM: Context: Impairment of proteasomal function is pathogenic in several cardiac proteinopathies and can eventually lead to heart failure. Loss of proteasomal activity often results in the accumulation of large protein aggregates. The ubiquitin proteasome system (UPS) is primarily responsible for cellular protein degradation, and although the role of ubiquitination in this process is well studied, the function of an ancillary post-translational modification, SUMOylation, in protein quality control is not fully understood.', 'To determine the role of ubiquitin-conjugating enzyme 9 (UBC9), a small ubiquitin-like modifier-conjugating enzyme, in cardiomyocyte protein quality control.', 'Gain- and loss-of-function approaches were used to determine the importance of UBC9. Overexpression of UBC9 enhanced UPS function in cardiomyocytes, whereas knockdown of UBC9 by small interfering RNA caused significant accumulations of aggregated protein. UPS function and relative activity was analyzed using a UPS reporter protein consisting of a short degron, CL1, fused to the COOH-terminus of green fluorescent protein (GFPu). Subsequently, the effects of UBC9 on UPS function were tested in a proteotoxic model of desmin-related cardiomyopathy, caused by cardiomyocyte-specific expression of a mutated αB crystallin, CryAB(R120G). CryAB(R120G) expression leads to aggregate formation and decreased proteasomal function. Coinfection of UBC9-adenovirus with CryAB(R120G) virus reduced the proteotoxic sequelae, decreasing overall aggregate concentrations. Conversely, knockdown of UBC9 significantly decreased UPS function in the model and resulted in increased aggregate levels.
Answer: UBC9 plays a significant role in cardiomyocyte protein quality control, and its activity can be exploited to reduce toxic levels of misfolded or aggregated proteins in cardiomyopathy.

SOLUTION:
Is sumo E2 enzyme UBC9 required for efficient protein quality control in cardiomyocytes?