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.

[EX Q]: Large concentrations of meperidine inhibit N-methyl-D-aspartate-(NMDA) receptor channels by channel block mechanisms. Extracellular pH regulates the activity and drug sensitivity of NMDA-receptor channels. We examined the influence of extracellular pH on sensitivity to meperidine of epsilon/zeta heteromeric NMDA-receptor channels expressed in Xenopus oocytes. Inhibition of epsilon1/zeta1, epsilon2/zeta1, epsilon3/zeta1, and epsilon4/zeta1 channels by meperidine was dependent on pH, with more inhibition at acidic pH and less inhibition at alkaline pH. The degree of voltage-dependence of meperidine block was only slightly affected by changes in pH, whereas affinity for meperidine was greatly reduced at alkaline pH. Furthermore, interaction of meperidine with Mg(2+) block was reduced at alkaline pH. Because the percentage of the protonated form of meperidine is only slightly affected by pH, changes in properties of the meperidine binding site may be involved in mechanisms of alteration of meperidine potency by pH.
[EX A]: Is n-methyl-D-aspartate receptor channel block by meperidine dependent on extracellular pH?

[EX Q]: Body weight correlates with risk of breast cancer death.', 'A retrospective cohort study using patient medical records, electronic cancer registry data, and archived tissue specimens.', 'A 395-bed, comprehensive community hospital.', 'One thousand three hundred seventy-six women, aged 24 to 81 years, who were diagnosed with breast cancer between January 1, 1988, and December 31, 1995, and for whom complete medical records and adequate tissue specimens existed.', "Body weight at the time of diagnosis and patient status (ie, alive and free of breast cancer, living with breast cancer, dead of breast cancer, or dead of other cause) at the time of longest follow-up. Additional data collected, including age at diagnosis, menopausal status, tumor size, tumor grade, lymph node status, stage at diagnosis, race, estrogen-receptor (ER) status, and treatment information, were used to create multivariate Cox proportional hazards models to estimate hazard rate (HR) ratios and 95% confidence intervals (CIs) for breast cancer death. We collected ER status from the patients' medical records, when available, and supplemented the information by using immunohistochemical techniques to determine ER status from archived paraffin-embedded tumor blocks.", 'Patients were followed up for a median of 6.8 years after diagnosis. Two hundred forty-six patients died from breast cancer. Among patients with early-stage disease (I and IIA), we observed a dose-response relationship of increasing weight with increasing likelihood of dying of breast cancer. Compared with women in the lowest category of weight (< 133 lb [60 kg] at diagnosis), women in the highest category (> or = 175 lb [79 kg]) experienced a 2.5-fold increased risk of dying from breast cancer (HR ratio, 2.54 [95% CI, 1.08-6.00]; trend P = .02). Women with ER-negative cancer experienced an approximately 2-fold higher risk of dying from breast cancer compared with women with ER-positive cancer, regardless of stage at diagnosis. Women in the upper 50th percentile of weight with early-stage disease and with ER-negative tumors had a nearly 5-fold increased risk of dying (HR ratio, 4.99 [95% CI, 2.17-11.48]; P for interaction = .10) compared with women in the lower 50th percentile of weight and ER-positive tumors. The results were similar for body mass index, a measure of obesity in which weight is adjusted for height.
[EX A]: Does body weight correlate with mortality in early-stage breast cancer?

[EX Q]: To study the impact of the new pharmacological treatment strategies in Parkinson's disease by analysis of the sales of dopaminergic drugs in Sweden 1990-2001.", 'Invoice statistics and statistics on prescription sales of dopaminergic drugs 1990-2001 were obtained from the 906 public pharmacies and the 89 hospital pharmacies in Sweden. The Swedish Diagnosis and therapy survey was used to study the diagnosis the drugs were prescribed for.', 'During the period the sales expressed in DDD/1000 inhabitants and day increased from 1.75 to 1.86 (6%) for levodopa and from 0.04 to 0.27 (575%) for dopamine agonists. The increase in sales of dopamine agonists occurred after 1997 and consisted entirely of the sales of the new agonists, cabergoline, pramipexole and ropinirole. In Swedish crowns the total sales of dopaminergic drugs increased with 126% during the period. The cost for the dopamine agonists was 8% of the total cost for dopaminergic drugs in 1990 and 23% in 2001. The prescription sales figures of levodopa and dopamine agonists for the different Swedish counties in 2001 varied between 1.52 and 2.44 and 0.13 and 0.74 DDD/1000 inhabitants and day, respectively. There was no correlation, whether positive or negative, between the sales of dopamine agonists, levodopa and COMT inhibitors or between the sales and the densities of neurologists.
[EX A]:
Have the increased utilisation of dopamine agonists and the introduction of COMT inhibitors reduced levodopa consumption -- a nation-wide perspective in Sweden?