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.

[EX Q]: Context: Before desflurane is advocated for patients undergoing neurosurgical procedures, it is necessary to determine the effect of desflurane on cerebral blood flow (CBF). In this study, CBF values are compared between desflurane and isoflurane at two doses. In addition, CBF reactivity to CO2 and the effect of prolonged exposure were compared between the two agents.', 'Cerebral blood flow measurements with intravenous 133Xe were performed in 24 patients undergoing craniotomy for mass lesions, randomized to receive either isoflurane or desflurane in oxygen and air. Cerebral blood flow was determined at 1 and 1.5 MAC concentrations at PaCO2 of 25 mmHg in the absence of surgical stimulation. Intraoperatively, with 1.25 MAC anesthesia, CBF was determined at target PaCO2 of 25 and 35 mmHg. In 15 patients, an additional measurement at 1.25 MAC was made before closure.', 'At 1.0 MAC, mean +/- SD CBF values for the desflurane and isoflurane groups were 18 +/- 2 and 20 +/- 3 ml x 100 g-1 x min-1, respectively. At 1.5 MAC, CBF values were the same for the two anesthetics; 17 +/- 3 ml x 100 g-1 x min-1 for isoflurane and 19 +/- 4 ml.100 g-1 x min-1 for desflurane. During 1.25 MAC anesthesia, there were no differences between groups, with CO2 reactivity 1.3 +/- 1.2 ml x 100 g-1 x min-1 x mmHg-1 for desflurane and 1.6 +/- 0.6 ml.100 g-1 x min-1 x mmHg-1 for isoflurane. There was no demonstrable decrease in CBF with prolonged exposure to either agent.
Answer: Desflurane and isoflurane are similar in terms of absolute CBF, the response to increasing doses, and the preservation of CO2 reactivity.
[EX A]: Do desflurane and isoflurane have similar effects on cerebral blood flow in patients with intracranial mass lesions?

[EX Q]: Context: Psychomotor abnormalities characterize both unipolar (UP) depression and bipolar (BP) depression. We aimed to assess their neurobiological correlates in terms of motor activity (AL) and resting-state cerebral blood flow (rCBF) and investigate their association in BP, UP, and healthy controls (HC).', 'We enrolled 42 depressed patients (22 BP, 20 UP) and 19 HC matched for age, gender, education, income. AL and rCBF were objectively assessed with the use of wrist actigraphy and arterial spin labeling. Group differences and the association of AL and rCBF were computed.', 'Activity level was significantly reduced in patients, but no difference was found between BP and UP. Increased perfusion was found in BP compared with UP and HC, in multiple brain areas. We found positive correlations of rCBF and AL in BP and UP, in different parts of the insula and frontal regions. Only BP showed a cluster in the left precentral gyrus. In HC, only inverse correlations of AL and rCBF were found.
Answer: The differences in rCBF and in the localization of the clusters of positive AL/rCBF correlations between BP and UP suggest that different neural impairments may underlie motor symptoms in the two disorders, but finally converge in phenotypically similar manifestations.
[EX A]: Do distinct resting-state perfusion patterns underlie psychomotor retardation in unipolar vs. bipolar depression?

[EX Q]: Context: Critical size defects (CSDs) of bone are defined as defects that do not heal spontaneously to new bone during the lifetime of an adult individual. In contrast, immature animals are capable to heal defects of identical size. It was our hypothesis that age-related paracrine effects are relevant for this difference in regeneration.', 'The pooled supernatant of primary rat calvarial osteoblast-like cell cultures (POBC) derived from prenatal or postnatal donors was concentrated and applied into CSDs of adult recipient organisms (n = 10). In addition, the supernatant of POBC derived from prenatal donors was pooled and purified by reverse-phase chromatography. Each pre-purified fraction was tested in a proliferation indicating bioassay. Peptide fractions containing proliferative activities were re-chromatographed and re-tested in a bioassay. Finally, a proliferative activity was purified, identified by sequence analysis and applied into CSDs of adult recipients.', 'The application of POBC derived from prenatal donors resulted in osseous regeneration of a CSD in adult recipients, while the supernatant of postnatal donors had much smaller effects. The morphologic features resembled the spontaneous osseous healing of calvarial defects of the same size in immature organisms. The polypeptide "tissue inhibitor of metalloproteinases type II"(TIMP-2) was isolated from the supernatant of cultures of POBC derived from prenatal donors by measuring the induction of their proliferation. Additionally, the application of human TIMP-2 injected into calvarial CSDs of adult organisms resulted in osseous healing.
Answer: We conclude that one component responsible for the healing effect of CSDs of POBC supernatants derived from prenatal donors is TIMP-2.
[EX A]:
Is tissue inhibitor of metalloproteinases II ( TIMP-2 ) an osteoanabolic factor in vitro and in vivo?