TASK DEFINITION: In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
PROBLEM: Context: B-type natriuretic peptide (BNP) correlates with cardiac filling pressures and outcomes in patients with heart failure. In heart transplant recipients, we hypothesize that a within-individual change in BNP over time would be more helpful than absolute BNP in detecting International Society of Heart and Lung Transplantation (ISHLT) grade 2R or greater rejection.', 'N-terminal pro-BNP (NT-proBNP) levels were measured in 146 consecutive transplant recipients undergoing routine endomyocardial biopsies. In the cross-sectional analysis, multiple observations per individual were accounted for using generalized estimation equations.', "A cross-sectional analysis demonstrated a weak association between NT-proBNP levels and rejection, with an odds ratio (OR) of 1.01 for every 100-pg/mL increase in NT-proBNP (p = 0.02). However, with a doubling of an individual's NT-proBNP level, the OR for significant rejection was 2.9 (95% confidence interval [CI] 1.2-7.0), the OR with a 5-fold increase was 9.1 (95% CI, 2.7-31.5), and the OR with a 10-fold increase was 27.7 (95% CI, 5.9-129). A 10-fold increase in NT-proBNP offered a negative predictive value of 95% for the diagnosis of rejection. The relationship between within-individual increases in NT-proBNP and rejection persisted after adjusting for a fall in ejection fraction and a rise pulmonary capillary wedge pressure, and was a stronger predictor than changes in these parameters.\Question: Does the change in B-type natriuretic peptide levels over time predict significant rejection in cardiac transplant recipients?

SOLUTION: There is a strong, graded relationship between the within-individual increase in NT-proBNP and the odds of significant rejection independent of hemodynamic parameters. These results suggest that the change in NT-proBNP rather than absolute BNP levels may offer a non-invasive approach to detect rejection.

PROBLEM: Context: Perls' stain is routinely used to demonstrate iron in liver biopsies. We tested the hypothesis that it may be unnecessary in cases, where no iron or another similar pigment was seen on the routine hematoxylin and eosin (H and E) stained section.", "The aim of this study was to evaluate the efficiency of H and E stain in demonstrating iron in liver biopsies as well as to determine the possibility of replacing Perls' stain with H and E stain.", "Two hundred pairs of slides of liver biopsies were taken from the archival files of the Department of Pathology from 2006 to 2011. Perls' and H and E slides were independently reviewed for the presence of iron.", "Hundred and one cases showed the presence of iron using H and E stain. 84 of 86 cases showed positive iron using both Perls' and H and E stains. Seventeen cases were positive using H and E stain but negative with Perls'. Only two cases did not show the presence of iron using H and E stain. Ninety-seven cases were negative using both Perls' and H and E stains. H and E stain showed a sensitivity, specificity, accuracy, positive predictive valve, and negative predictive value of 97.67%, 85.08%, 90.5%, 83.16%, and 97.98%, respectively.\Question: Do hematoxylin and eosin stain shows a high sensitivity but sub-optimal specificity in demonstrating iron pigment in liver biopsies?

SOLUTION: We demonstrate that the H and E stain is a sensitive method to detect iron pigment in liver biopsies, particularly when present in large quantities. A negative H and E stain might obviate the need for extra Perls' staining, thus saving costs and shortening report turn-around times.

PROBLEM: Context: Pineal function has been considered particularly as a neuroendocrine modulator in hormone responsive tumors, like the hormone-dependent mammary tumors. The complexity of the gland function, moreover, is denoted by the presence of a local renin-angiotensin-system (RAS) that regulates melatonin biosynthesis. Classically, angiotensin II (Ang II) has been considered as the effector peptide of the RAS, but Ang II is not the only active peptide. Several of its degradation products, including angiotensin III (Ang III) and angiotensin IV (Ang IV) also possess biological functions. These peptides are formed via the activity of several aminopeptidases. Our aim is to know their role in the regulation of pineal RAS and breast cancer.', 'Aminopeptidase N (APN), aminopeptidase B (APB) and aminopeptidase A (aspartyl- and glutamyl-aminopeptidase, APA) activities are measured in the pineal gland of rats with breast cancer induced by N-methyl nitrosourea (NMU).', 'Aminopeptidase activities were measured fluorimetrically using their corresponding aminoacyl-beta-naphthylamides as substrates.', 'Specific APN and APB activities in pineal gland of controls and NMU-treated rats were not modified. Aspartyl aminopeptidase activity significantly decreased in NMU-treated rats when compared with control group. On the contrary, glutamyl aminopeptidase activity did not show significant differences between groups.\Question: Are renin-angiotensin system-regulating aminopeptidase activities modified in the pineal gland of rats with breast cancer induced by N-methyl-nitrosourea?

SOLUTION:
We propose that the local RAS in pineal gland is modified in rats with breast cancer induced by NMU through the inhibition of AspAP activity, which may lead to increased levels of Ang II. Ang II could be responsible of the overproduction of melatonin, supporting a mechanism to restrain the promotion and/or progression of breast cancer.