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: 99mTc-HMPAO is a well-established isotope useful in the detection of regional cerebral blood flow. Diabetes gives rise to arterial atherosclerotic changes that can lead to significant end organ dysfunction, prominently affecting perfusion to the heart, kidneys, eyes and brain. In the current study, we investigated the role of 99mTc-HMPAO cerebral perfusion scans in detecting early vascular changes in the diabetic brain.', 'Cerebral perfusion studies were performed on both control and streptozotocin-(STZ) induced diabetic male Wistar rats. Rat brain imaging using a gamma camera was performed for each group 0.5, 2, 4, and 24 hours post 99mTc-HMPAO injection. Data processing for each cerebral perfusion scan was performed by drawing a region of interest (ROI) circumferentially around the brain (B). Background (BKG) due to signal from the soft tissue of each rat was subtracted. Brain 99mTc-HMPAO uptake minus background counts (net brain counts; NBC) were then compared between the two groups.', 'The NBC (mean +/- SD) for the STZ group were statistically significantly higher (p = 0.0004) than those of the control group at each of the time points studied.
Answer: 99mTc-HMPAO brain scan may be useful in the detection of early atherosclerotic changes in the diabetic rat brain.

SOLUTION: Does perfusion scanning using 99mTc-HMPAO detect early cerebrovascular changes in the diabetic rat?

PROBLEM: Context: Tissue factor (TF) contributes to thrombosis following plaque disruption in acute coronary syndromes (ACS). Aim of the study was to investigate the impact of plasma TF activity on prognosis in patients with ACS.', 'One-hundred seventy-four patients with unstable Angina pectoris (uAP) and 112 patients with acute myocardial infarction (AMI) were included with a mean follow up time of 3.26 years. On admission, plasma TF activity was assessed. Patients were categorized into 2 groups: a high-TF activity group with TF >24 pmol/L and low TF activity group with TF ≤ 24 pmol/L. Fifteen cardiovascular deaths occurred in the uAP group and 16 in the AMI group. In AMI TF activity was 24,9 ± 2,78 pmol/l (mean ± SEM) in survivors and 40,9 ± 7,96 pmol/l in nonsurvivors (P = 0.024). In uAP no differences were observed (25.0 ± 8.04 pmol/L nonsurvivors vs. 25.7 ± 2.14 pmol/L survivors; P = 0.586). Kaplan-Meier estimates of survival at 3.26 years regarding TF activity in AMI were 81.3% and 92.2% with an hazard ratio of 3.02 (95% CI [1.05-8.79], P = 0.03). The Cox proportional hazards model adjusting for correlates of age and risk factors showed that plasma TF activity was an independent correlate of survival (hazard ratio 9.27, 95% CI [1.24-69.12], P = 0.03). In an additional group of patients with uAP and AMI, we identified circulating microparticles as the prevailing reservoir of plasma TF activity in acute coronary syndromes.
Answer: Systemic TF activity in AMI has an unfavorable prognostic value and as a marker for dysregulated coagulation may add to predict the atherothrombotic risk.

SOLUTION: Does plasma TF activity predict cardiovascular mortality in patients with acute myocardial infarction?

PROBLEM: Context: This study was undertaken to determine the survival benefit of extending resections to obtain microscopically negative margins after positive intraoperative frozen sections.', 'The impact of residual microscopic disease after pancreaticoduodenectomy is currently a point of controversy. It is, however, generally believed that microscopically positive margins negatively impact survival and this may be improved by ultimately achieving negative margins.', 'Since 1995, patients undergoing pancreaticoduodenectomy for pancreatic adenocarcinoma have been prospectively followed. Margin status has been codified as macro/microscopically negative (R0) or macroscopically negative/microscopically positive (R1). The impact of margin status on survival was evaluated utilizing survival curve analysis. Data are presented as median, mean +/- SD where appropriate.', 'For pancreatic adenocarcinoma, 202 patients underwent pancreaticoduodenectomy. R0 resections were achieved in 158 patients, 17 of whom required extended resections to achieve complete tumor extirpation after an initially positive intraoperative frozen section (R1 --> R0). R1 resections were undertaken in 44 patients. Median survival for patients undergoing R0 resections was 21 months, 26 +/- 23.4 months versus 13 months, 17 +/- 21.0 months for patients undergoing R1 resections (P = 0.02). Median survival for patients undergoing R1 --> R0 resections was 11 months, 16 +/- 17.3, (P = 0.001). Margin status had a significant correlation with "N" stage and AJCC stage but not "T" stage.
Answer: Survival after pancreaticoduodenectomy is not improved by extending pancreatic resections to achieve negative margins after initially positive intraoperative frozen sections. Tumor-specific factors beyond the presence of disease at a surgical margin are responsible for the abbreviated survival seen in patients undergoing R1 resections.

SOLUTION:
Is survival after pancreaticoduodenectomy improved by extending resections to achieve negative margins?