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.

Context: Diabetic retinopathy (DR) is a retinopathy resulting from diabetes mellitus (DM) which was classified into non-proliferative DR (NPDR) and proliferative DR (PDR). Without an early screening and effective diagnosis, patients with PDR will develop serious complications. Therefore, we sought to identify special serum microRNAs (miRNAs) that can serve as a novel non-invasive screening signature of PDR and test its specificity and sensitivity in the early diagnosis of PDR.', 'In total, we obtained serum samples from 90 PDR cases, 90 matched NPDR patients and 20 controls. An initial screening of miRNA expression was performed through TaqMan Low Density Array (TLDA). The candidate miRNAs were validated by individual reverse transcription quantitative real-time PCR (RT-qPCR) arranged in an initial and a two-stage validation sets. Moreover, additional double-blind testing was performed in 20 patients clinically suspected of having DR to evaluate the diagnostic value and accuracy of the serum miRNA profiling system in predicting PDR.', 'Three miRNAs were significantly increased in patients with PDR compared with NPDR after the multiple stages. The areas under the receiver operating characteristic (ROC) curves of the validated three-serum miRNAs signature were 0.830, 0.803 and 0.873 in the initial and two validation sets, respectively. Combination of miR-21, miR-181c, and miR-1179 possessed a moderate ability to discrimination between PDR and NPDR with an area under ROC value of 0.89. The accuracy rate of the three-miRNA profile as PDR signature was 82.6%.
Answer: These data provide evidence that serum miRNAs have the potential to be sensitive, cost-effective biomarkers for the early detection of PDR. These biomarkers could serve as a dynamic monitoring factor for detecting the progression of PDR from NPDR.
Do serum miRNA biomarkers serve as a fingerprint for proliferative diabetic retinopathy?

Context: Preoperative anemia may affect postoperative mortality and morbidity following elective cranial operations.', 'The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was used to identify elective cranial neurosurgical cases (2006-2012). Morbidity was defined as wound infection, systemic infection, cardiac, respiratory, renal, neurologic, and thromboembolic events, and unplanned returns to the operating room. For 30-day postoperative mortality and morbidity, adjusted odds ratios (ORs) were estimated with multivariable logistic regression.', 'Of 8015 patients who underwent elective cranial neurosurgery, 1710 patients (21.4%) were anemic. Anemic patients had an increased 30-day mortality of 4.1% versus 1.3% in non-anemic patients (P < 0.001) and an increased 30-day morbidity rate of 25.9% versus 14.14% in non-anemic patients (P < 0.001). The 30-day morbidity rates for all patients undergoing cranial procedures were stratified by diagnosis: 26.5% aneurysm, 24.7% sellar tumor, 19.7% extra-axial tumor, 14.8% intra-axial tumor, 14.4% arteriovenous malformation, and 5.6% pain. Following multivariable regression, the 30-day mortality in anemic patients was threefold higher than in non-anemic patients (4.1% vs 1.3%; OR = 2.77; 95% CI: 1.65-4.66). The odds of postoperative morbidity in anemic patients were significantly higher than in non-anemic patients (OR = 1.29; 95% CI: 1.03-1.61). There was a significant difference in postoperative morbidity event odds with a hematocrit level above (OR = 1.07; 95% CI: 0.78-1.48) and below (OR = 2.30; 95% CI: 1.55-3.42) 33% [hemoglobin (Hgb) 11 g/dl].
Answer: Preoperative anemia in elective cranial neurosurgery was independently associated with an increased risk of 30-day postoperative mortality and morbidity when compared to non-anemic patients. A hematocrit level below 33% (Hgb 11 g/dl) was associated with a significant increase in postoperative morbidity.
Does preoperative anemia increase postoperative morbidity in elective cranial neurosurgery?

Context: Escalation in monocyte trafficking from the bone marrow into the brain may play a critical role in central nervous system injury and cognitive deterioration in patients with HIV infection. This study tested the hypothesis that the mean diffusivity is sensitive to marrow changes in HIV patients and that these quantitative imaging measurements correlate with the severity of dementia.', 'The mean diffusivity (MD), determined for clival and calvarial marrow regions, was compared in 11 HIV-infected patients and 9 control subjects. The imaging measurements were also evaluated for relationships with dementia severity and markers of disease progression (CD4 and viral load in plasma).', 'The MD was significantly reduced in both clival and calvarial marrow in HIV-infected patients (P =.006). Diffusion measurements for clival (P =.02) and for calvarial (P =.03) regions were significantly correlated with the severity of dementia.
Answer: The results of this investigation support the utility of diffusion strategies for monitoring the marrow and provide further evidence of a relationship between marrow status changes and neurologic progression in HIV patients.

Do bone marrow diffusion measures correlate with dementia severity in HIV patients?