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.

Hyponatraemia is a common, potentially life-threatening, complication of thiazide diuretics. The mechanism of thiazide-induced hyponatraemia is incompletely understood. Previous experiments have suggested a direct effect of thiazide diuretics on the plasma membrane expression of aquaporin (AQP)2.', 'We examined the effects of a single re-exposure to hydrochlorothiazide (HCTZ) 50mg on water balance, renal sodium handling and osmoregulation in 15 elderly hypertensive patients with a history of thiazide-induced hyponatraemia and 15 matched hypertensive controls using thiazide diuretics without previous hyponatraemia.', 'Patients with thiazide-induced hyponatraemia had significantly lower body weight and lower plasma sodium and osmolality at baseline. After HCTZ administration, plasma sodium and osmolality significantly decreased and remained lower in patients compared with controls (P<0.001). Plasma antidiuretic hormone (ADH) and urine AQP2 were low or suppressed in patients, whereas solute and electrolyte-free water clearance was significantly increased compared with controls. Ad libitum water intake was significantly higher in patients (2543925ml) than in controls (1828624ml, P<0.05), whereas urinary sodium excretion did not differ. In contrast, urea excretion remained significantly lower in patients (26369mmol per 24h) compared with controls (33397mmol per 24h, P<0.05) and predicted the decrease in plasma sodium following HCTZ administration.
Is thiazide-induced hyponatraemia associated with increased water intake and impaired urea-mediated water excretion at low plasma antidiuretic hormone and urine aquaporin-2?

Transmural heterogeneity in ventricular repolarization demonstrated in vitro has been difficult to confirm in vivo. Whether this discrepancy reflects a physiological phenomenon or a methodological problem remains a vivid matter of debate despite a plethora of experimental work. Therefore, we have measured the relevant electrophysiological parameters first in vivo and repeated these in the same heart and at identical sites in vitro. Methodological issues were tackled by using both unipolar and bipolar recordings. Physiological issues were explored by measuring both local and functional electrophysiological parameters.', 'In 10 healthy dogs, 2 high-resolution needle electrodes were inserted into the left ventricle. Effective refractory periods (ERP) as well as activation recovery intervals (ARI) were determined at each electrode along both needles at basic cycle lengths (BCL) of 850 and 300 ms, respectively. After excision of the heart, ERP and ARI measurements were repeated in the arterially perfused wedge preparations.', 'First, we observed that ERPs and ARIs were significantly shorter in vivo than in vitro. Mean ERPs and ARIs of all muscle layers were relatively uniform throughout the ventricular wall in vivo. The transition from the in vivo to the in vitro preparation was associated with a significant albeit small increase of mean ARIs in the subendocardium, whereas interlayer differences in mean ERPs did not reach statistical significance as in vivo.
Is there no transmural heterogeneity in an index of action potential duration in the canine left ventricle?

Vascular pathology is associated with reduced performance on neuropsychological tests, particularly in older adults. A likely explanation involves a disruption in the blood brain barrier (BBB). Work from clinical samples show alterations in BBB function is associated with cognitive dysfunction on testing, though no study has examined this possibility in healthy older adults.', '35 older adults, without significant neurological or psychiatric history, underwent fasting blood draw and neuropsychological testing. Serum levels of S100beta were quantified to provide a measure of BBB function.', 'Partial correlations showed S100beta levels were inversely related to performance in multiple cognitive domains, including memory (r = 0.43, p = 0.02), psychomotor speed and visual attention (r = 0.37, p = 0.05), and working memory (r = -0.48, p = 0.008).
Is increased S100beta associated with reduced cognitive function in healthy older adults?