Given a passage with a context and an answer, 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.

Q: Context: To test whether subsensory vibratory noise applied to the sole of the foot using a novel piezoelectric vibratory insole can significantly improve sensation, enhance balance, and reduce gait variability in elderly people, as well as to determine the optimal level of vibratory noise and whether the therapeutic effect would endure and the user's sensory threshold would remain constant during the course of a day.", 'A randomized, single-blind, crossover study of 3 subsensory noise stimulation levels on 3 days.', 'Balance and gait laboratory.', 'Healthy community-dwelling elderly volunteers (N=12; age, 65-90y) who could feel the maximum insole vibration.', 'A urethane foam insole with the piezoelectric actuators delivering subsensory vibratory noise stimulation to the soles of the feet.', 'Balance, gait, and timed Up and Go (TUG) test.', 'The vibratory insoles significantly improved performance on the TUG test, reduced the area of postural sway, and reduced the temporal variability of walking at both 70% and 85% of the sensory threshold and during the course of a day. Vibratory sensation thresholds remained relatively stable within and across study days.
Answer: This study provides proof of concept that the application of the principle of stochastic resonance to the foot sole sensory system using a new low-voltage piezoelectric technology can improve measures of balance and gait that are associated with falls. Effective vibratory noise amplitudes range from 70% to 85% of the sensory threshold and can be set once daily.

A: Does a shoe insole delivering subsensory vibratory noise improve balance and gait in healthy elderly people?
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Q: Context: Most solid human tumors exist in an acidic microenvironment, due in part to inefficient vasculature and a higher intrinsic rate of glycolysis. This leads to a tumor-selective pH gradient, which can be exploited therapeutically with antitumor agents such as the camptothecins (CPTs). Previous work in this laboratory has shown that camptothecin activity is enhanced 40- to 60-fold in monolayer cell culture by reducing the extracellular pH to 6.8. Three-dimensional histoculture has been shown to be a technique that allows human tumor tissue to grow in an in vivo-like way with maintenance of tissue histology and function and drug sensitivity for long periods of time.', 'In the current study, we utilized these features of histoculture to study new analogues of camptothecin that have superior pharmacological properties.', 'We evaluated six CPT analogues in histocultures of human brain, neuroblastoma, breast, colon, and prostate tumors. Fragments were exposed to 10,11-methylenedioxy-CPT (MDC), 7-chloromethyl-MDC, SN-38, topotecan (TPT), 9-amino-CPT, 10-amino-CPT, paclitaxel, 5-fluorouracil, 4-hydroperoxycyclophosphamide and doxorubicin, and antitumor activity was assessed. For in vivo tumor outgrowth studies, fragments were treated in parallel, implanted into nude mice, and monitored for development of tumors. RESULTS. Against 15 of 16 tumor xenografts and all primary tumor samples tested, all compounds were cytotoxic at pH 7.4 (IC(50) range 13-921 microM). MDC, SN-38, TPT, and 9-amino-CPT achieved an average 5-fold increase in activity (range 3-14) at pH 6.8, while 7-chloromethyl-MDC was enhanced 8-fold (range 6-14). The most potentiated analogue was 10-amino-CPT at 27-fold (range 17-49). In contrast, the other agents were active against one or more tumor types but were not enhanced by acidic pH. Importantly, the toxicity of MDC in histoculture of D54 glioma xenografts strongly correlated with the outgrowth of treated fragments subsequently implanted in vivo.
Answer: Evaluation of anticancer drug activity in native-state histoculture supports the concept that pH modulation may be an important approach to improve the selectivity and antitumor effectiveness of camptothecin-based chemotherapy.

A: Is the activity of camptothecin analogues enhanced in histocultures of human tumors and human tumor xenografts by modulation of extracellular pH?
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Q: Context: It has been contended that, during cardiopulmonary bypass at 27 degrees C, pH-stat management decreases cerebral metabolic rate for oxygen (CMRO2) more than alpha-stat management. In contrast, other studies have not found CMRO2 to differ between techniques. Using each animal as its own control, the authors assessed the effect of alpha-stat versus pH-stat management of CMRO2, cerebral blood flow (CBF), and brain oxygen extraction during cardiopulmonary bypass at 27 degrees C.', 'Fourteen New Zealand White rabbits, anesthetized with fentanyl and diazepam, underwent cardiopulmonary bypass at 27 degrees C (membrane oxygenator, centrifugal pump, and bifemoral arterial perfusion). Group 1 animals (n = 7) had alpha-stat management for the initial 65-70 min of bypass, and were then changed to pH-stat management for the remaining 30 min of bypass. Group 2 animals (n = 7) had pH-stat management for the initial 65-70 min of bypass, and were then changed to alpha-stat management for the remaining 30 min. Measurement of CBF (radiolabeled microspheres), CMRO2 (CBF x brain arterial-venous oxygen content difference), brain temperature, systemic hemodynamics, and arterial blood gases were made in each animal under both alpha-stat and pH-stat conditions.', 'CMRO2 did not differ between alpha-stat and pH-stat conditions (1.4 +/- 0.3 ml.100 g-1.min-1; median +/- quartile deviation), and was independent of order of determination. Changes in CBF between alpha-stat and pH-stat conditions were associated with proportional opposite changes in cerebral oxygen extraction. Cerebral blood flow was significantly greater with pH-stat management than with alpha-stat management (37 +/- 5 vs. 30 +/- 3 ml.100 g-1.min-1, respectively). The CBF response to changing PaCO2 was significantly greater when going from alpha-stat to pH-stat conditions (group 1) than in the reverse order (group 2).
Answer: During cardiopulmonary bypass at 27 degrees C, hypothermic acid-base management has no measurable effect on CMRO2. CMRO2 was neither extraction limited nor dependent on either PaCO2, CBF, or hemoglobin oxygen affinity differences between alpha-stat and pH-stat management. Cerebral blood flow responses to changing CMRO2 depend on the "starting" conditions, with alpha-stat management appearing to better preserve CBF reactivity than pH-stat management.

A:
Does hypothermic acid-base management affect cerebral metabolic rate for oxygen at 27 degrees C. A study during cardiopulmonary bypass in rabbits?
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