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.

The risk of breast cancer in carriers of BRCA1 and BRCA2 mutations is influenced by factors other than the genetic mutation itself. Modifying factors include a woman's reproductive history and family history of cancer. Risk factors are more likely to be present in women with breast cancer than in women without breast cancer, and therefore the risk of cancer in the two breasts should not be independent. It is not clear to what extent modifying factors influence the risk of a first primary or a contralateral breast cancer in BRCA carriers.", 'We conducted a matched case-control study of breast cancer among 3920 BRCA1 or BRCA2 mutation carriers. We asked whether a past history of breast cancer in the contralateral breast was a risk factor for breast cancer.', 'After adjustment for age, country of residence, and cancer treatment, a previous cancer of the right breast was found to be a significant risk factor for cancer of the left breast among BRCA1 or BRCA2 carriers (relative risk: 2.1; 95% confidence interval: 1.4 to 3.0; p < 0.0001).
Is a prior diagnosis of breast cancer a risk factor for breast cancer in BRCA1 and BRCA2 carriers?

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?

Obstructive sleep apnoea (OSA) is a common and potentially reversible cause of systemic hypertension. The mechanisms whereby OSA leads to hypertension and the effects of treatment on arterial function, however, are not well established. Microvascular arterial endothelial and smooth muscle function was assessed in subjects with OSA before and after treatment with continuous positive airways pressure (CPAP).', 'Ten subjects of mean (SE) age 49 (8) years with at least moderately severe OSA had detailed forearm vascular reactivity studies before and after 3 months of CPAP treatment. The systemic circulation was assessed by measuring brachial artery pressure, flow and resistance responses to intra-arterial infusions of acetylcholine (ACh; an endothelium dependent vasodilator), sodium nitroprusside (SNP; an endothelium independent vasodilator), L-NMMA (a nitric oxide (NO) antagonist), and L-arginine (the substrate for NO).', 'Before CPAP, ACh and SNP infusions increased forearm blood flow in a dose dependent manner (p<0.01). After CPAP, endothelium dependent dilation to ACh was significantly increased (434 (23)% of baseline after CPAP v 278 (20)% before CPAP, p<0.001), whereas SNP induced dilation was unchanged. Resting NO production was higher after CPAP, evidenced by a significantly greater reduction in basal flow by L-NMMA (p=0.05). L-Arginine reversed the effect of L-NMMA in all cases.
Does treatment of obstructive sleep apnoea lead to improved microvascular endothelial function in the systemic circulation?