Given a passage, 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.

To compare the efficacy and safety of prophylactic modalities for heterotopic ossification prevention after elbow and acetabular surgeries.', 'The retrospective chart review was conducted at the Aga Khan University Hospital and comprised record of patients who underwent open reduction and internal fixation for elbow and acetabular fractures between 2010 and 2013. Data was classified into three groups: Group A patients had received single dose of radiotherapy; Group B patients had received indomethacin, and Group C patients had not received any prophylaxis. Outcome variables included time-to-fracture healing, heterotopic ossification, non-union and wound infection.', 'Of the 104patients 70(67.3%) had elbow fractures and 34(32.7%) had acetabular fractures. Out of the 70patients with elbow fractures, 28(27%) were in Group A, 24(23%) in Group B, and 18(17%) in Group C. In Group A, 4(22%) patients had wound infection compared to 1(5.5%) patient in Group C (p=0.131). One (4%) patient in Group B and 1(5.5%) in Group C developed heterotopic ossification (p=0.486). Non-union occurred in 1(4%) patient in Group B and 1(5.5%) in Group C. Out of the 34 patients with acetabular fractures, 11(32.3%) were in Group A, 10(29.4%) in Group B, and 13(38.2%) in Group C. In Group A, 2(18.2%) patients developed wound infection. Only 1(7.6%) patient in Group C developed heterotopic ossification.
Do prophylaxis against heterotopic ossification after elbow and acetabular fractures - Do we really need it?

While the incidence of inflammatory bowel disease (IBD) among African-Americans (AAs) is increasing, there is limited understanding of phenotypic differences and outcomes by race.', 'To describe disease characteristics of AA patients compared to Caucasian (Ca) patients in a tertiary care population.', "We performed a cross-sectional review of the IBD registry at the University of Chicago from January 2008 to January 2013. Data regarding race, phenotype, disease onset, disease duration, medical therapy, and surgical treatment were abstracted from the database, then compared via Pearson's chi-square analysis, Kruskal-Wallis analysis, and logistic regression with a significance level of p < 0.05.", "A total of 1,235 patients with Crohn's disease (CD) and 541 patients with ulcerative colitis (UC) included 108 AA CD patients and 28 AA UC patients. AA CD patients had an increased rate of IBD-related arthralgias (36.5 vs. 23.9 %, p < 0.01) and surgery (p < 0.01), less ileal involvement (57.8 vs. 71.0 %, p < 0.01), and no differences for other extraintestinal manifestations or disease locations compared to Ca CD patients. AA UC patients were older at diagnosis, had an increased rate of arthralgias (28.6 vs. 14.6 %, p = 0.047) and ankylosing spondylitis/sacroiliitis (7.1 vs. 1.6 %, p = 0.035), with no differences for disease extent or rate of IBD-related surgeries compared to Ca UC patients. There were no differences in medication usage by race for CD and UC patients.
Does clinical presentation and disease course of inflammatory bowel disease differ by race in a large tertiary care hospital?

Optical techniques are routinely used to size and count extracellular vesicles (EV). For comparison of data from different methods and laboratories, suitable calibrators are essential. A suitable calibrator must have a refractive index (RI) as close to that of EV as possible but the RI of EV is currently unknown. To measure EV, RI requires accurate knowledge of size and light scattering. These are difficult to measure as most EVs cannot be resolved by light microscopy and their diameter is smaller than the wavelength of visible light. However, nanoparticle tracking analysis (NTA) provides both size and relative light scattering intensity (rLSI) values. We therefore sought to determine whether it was possible to use NTA to measure the RI of individual EVs.', 'NTA was used to measure the rLSI and size of polystyrene and silica microspheres of known size and RI (1.470 and 1.633, respectively) and of EV isolated from a wide range of cells. We developed software, based on Mie scattering code, to calculate particle RI from the rLSI data. This modelled theoretical scattering intensities for polystyrene and silica microspheres of known size (100 and 200 nm) and RI. The model was verified using data from the polystyrene and silica microspheres. Size and rLSI data for each vesicle were processed by the software to generate RI values.', 'The following modal RI measurements were obtained: fresh urinary EV 1.374, lyophilised urinary EV 1.367, neuroblastoma EV 1.393, blood EV 1.398, EV from activated platelets 1.390, small placental EV 1.364-1.375 and 1.398-1.414 for large placental EV (>200 nm). Large placental EV had a significantly higher RI than small placental EV (p<0.0001). The spread of RI values was narrower for small EV than for the more heterogeneous large EV.

Does measurement of refractive index by nanoparticle tracking analysis reveal heterogeneity in extracellular vesicles?