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 Q]: Context: Osteoarthritis (OA) is associated with a gradual reduction in the interstitial osmotic pressure within articular cartilage. The aim of this study was to compare the effects of sudden and gradual hypo-osmotic challenge on chondrocyte morphology and biomechanics.', 'Bovine articular chondrocytes were exposed to a reduction in extracellular osmolality from 327 to 153 mOsmol/kg applied either suddenly (<5 s) or gradually (over 180 min). Temporal changes in cell diameter and the existence of regulatory volume decrease (RVD) were quantified along with changes in cortical actin and chromatin condensation. The cellular viscoelastic mechanical properties were determined by micropipette aspiration.', 'In response to a sudden hypo-osmotic stress, 66% of chondrocytes exhibited an increase in diameter followed by RVD, whilst 25% showed no RVD. By contrast, cells exposed to gradual hypo-osmotic stress exhibited reduced cell swelling without subsequent RVD. There was an increase in the equilibrium modulus for cells exposed to sudden hypo-osmotic stress. However, gradual hypo-osmotic challenge had no effect on cell mechanical properties. This cell stiffening response to sudden hypo-osmotic challenge was abolished when actin organization was disrupted with cytochalasin D or RVD inhibited with REV5901. Both sudden and gradual hypo-osmotic challenge reduced cortical F-actin distribution and caused chromatin decondensation.
Answer: Sudden hypo-osmotic challenge increases chondrocyte mechanics by activation of RVD and interaction with the actin cytoskeleton. Moreover, the rate of hypo-osmotic challenge is shown to have a profound effect on chondrocyte morphology and biomechanics. This important phenomenon needs to be considered when studying the response of chondrocytes to pathological hypo-osmotic stress.
[EX A]: Does the rate of hypo-osmotic challenge influence regulatory volume decrease ( RVD ) and mechanical properties of articular chondrocytes?

[EX Q]: Context: Elevated levels of B-type natriuretic peptide (BNP) are associated with adverse clinical outcomes in acute coronary syndrome (ACS), but several questions remain outstanding. Firstly, it has not yet been determined whether an additional BNP sample at 7 weeks post ACS would enhance risk prediction. Secondly, we assessed whether the prognostic potential of BNP in ACS could be explained by echocardiographic abnormalities such as left ventricular hypertrophy (LVH).', 'We measured bedside BNP levels in 443 consecutive patients presenting with ACS and at 7 weeks outpatient follow-up. Main outcome measure was either all-cause mortality, readmission with ACS, or congestive heart failure) at 10 months from presentation.', 'Of the 443 patients, 120 patients presented with ST-elevation myocardial infarction (27%). There were 90 cardiovascular (CV) events at 10 months. Adjusting for age, sex, hypertension, diabetes mellitus, smoking status, renal dysfunction, left ventricular ejection fraction, and echocardiographic LVH elevated near patient BNP levels (>80 pg/mL) were still associated with subsequent CV events when measured on admission (adjusted relative risk [RR] 2.63 [95% CI 1.34-5.19)] and also at 7 weeks post ACS (adjusted RR 4.12 [95% CI 1.58-10.72]). Patients with persistent BNP elevation at 7 weeks were also at an increased risk of CV events compared to those with an initial high BNP which then fell (unadjusted RR 4.04 [95% CI 1.24-13.15]).
Answer: In ACS, bedside BNP levels predict CV events at 10 months, independent of many echocardiographic abnormalities including LVH. Furthermore, our study suggests that an additional 7 weeks post ACS BNP enhances risk stratification over and above a one-off high BNP at baseline.
[EX A]: Does serial bedside B-type natriuretic peptide strongly predict prognosis in acute coronary syndrome independent of echocardiographic abnormalities?

[EX Q]: Context: Pre-operative restaging CT scans are often performed routinely following neoadjuvant chemoradiotherapy for locally advanced rectal cancer. There is a paucity of data on the utility of this common practice. We sought to determine how often restaging CTs identified disease progression or regression that altered management.', 'We performed a single-institution retrospective study. From 2007 to 2011, 182 patients had newly-diagnosed, non-metastatic rectal adenocarcinoma, of which 96 were surgical candidates with clinical stage II/III disease. Ninety-one of these patients (95%) completed neoadjuvant chemoradiation.', 'Eighty-three out of 91 patients (91%) had restaging CTs. Four patients (5%) had new lesions suspicious for distant metastasis (2 lung, 2 liver) on restaging CT scan reports (1 of these was present on initial staging CT but not reported). All 4 patients had node-positive disease. In no case did restaging CT result in a change in surgical management.
Answer: Because of the financial costs and established risks of intravenous contrast and cumulative radiation exposure, it may be advisable to take a more selective approach to preoperative imaging. Larger, prospective studies may enable identification of an at-risk cohort who would benefit most from restaging CT.
[EX A]:
Are routine preoperative restaging CTs after neoadjuvant chemoradiation for locally advanced rectal cancer low yield : a retrospective case study?