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: In patients with moderate-to-severe psoriasis, health-related quality of life (HRQOL) has been shown to improve in parallel with improvement in disease severity.', 'To evaluate the role of pruritus (itch) in mediating the relationship between improvements in disease severity and HRQOL.', 'Data from a phase 2 clinical trial, in which 142 patients with moderate-to-severe plaque psoriasis received ixekizumab or placebo, were used for this posthoc analysis. Relationships between improvement in Psoriasis Area and Severity Index (PASI), Itch Visual Analogue Scale (VAS) and Dermatology Life Quality Index (DLQI), as well as in individual DLQI domains (symptoms and feelings, treatment, work and school, daily activities, leisure, and personal relationships) from baseline to week 16 were determined. Multiple hierarchical linear regressions and Sobel tests were conducted to evaluate the results.', 'Improvement in PASI was highly correlated with pruritus improvement and improvements in DLQI total and domain scores at week 16 (P\xa0<\xa00·01). Multiple hierarchical linear regression analyses showed a statistically significant (P\xa0<\xa00·01) association between improvement in pruritus and improvement in DLQI total score and each of the six DLQI domain scores after adjusting for improvement in PASI. Sobel tests indicated that pruritus had a significant mediation effect (P\xa0<\xa00·05) on the association of PASI improvement with improvement in DLQI total score and all domains except the personal relationships score.
Answer: Pruritus appears to be an important mediator of the association between improvements in disease severity and HRQOL in patients with moderate-to-severe psoriasis.
[EX A]: Is itching a significant problem and a mediator between disease severity and quality of life for patients with psoriasis : results from a randomized controlled trial?

[EX Q]: Context: Cell death induced by intracellular glutathione depletion has been reported to be dependent on the presence of trace amounts of extracellular copper ions. Since little is known about the relationship between glutathione depletion and copper homeostasis, we have in the present study further investigated the role of low amounts of copper ions in glutathione depletion.', 'Glutathione turnover was investigated in HeLa and hepatoma cell cultures with normal and low cysteine content in the presence of copper ions (1 and 10micromol/L) and two other glutathione-stimulating agents (lipoic acid and mercury ions).', 'Copper ions (10micromol/L) caused relatively small increases in total amount of glutathione (the sum of the intracellular and the extracellular amount of glutathione) in HeLa and hepatoma cell cultures with normal cysteine levels (420nmol/mL) compared to control cell cultures, whereas lipoic acid and mercury ions strongly increased total glutathione in both types of cell cultures. Lower amount of total glutathione was observed in cell cultures with a lower cysteine levels (84nmol/mL), which is similar to that in human plasma. A strongly decreased total amount of glutathione in the presence of copper ions was observed in hepatoma cell cultures with lower cysteine levels, whereas the other agents showed effects similar to those described for cell cultures with normal cysteine levels.
Answer: Glutathione synthesis in hepatoma cell cultures is probably more sensitive to a low cysteine level than HeLa cell cultures, and the presence of copper ions further decreases the availability of cysteine probably by increasing the disulfide binding to cysteine residues in extracellular proteins, which causes a further decrease of total glutathione.
[EX A]: Do traces of copper ions deplete glutathione in human hepatoma cell cultures with low cysteine content?

[EX Q]: Context: Although prevalent in prokaryotes, horizontal gene transfer (HGT) is rarer in multicellular eukaryotes. Bdelloid rotifers are microscopic animals that contain a higher proportion of horizontally transferred, non-metazoan genes in their genomes than typical of animals. It has been hypothesized that bdelloids incorporate foreign DNA when they repair their chromosomes following double-strand breaks caused by desiccation. HGT might thereby contribute to species divergence and adaptation, as in prokaryotes. If so, we expect that species should differ in their complement of foreign genes, rather than sharing the same set of foreign genes inherited from a common ancestor. Furthermore, there should be more foreign genes in species that desiccate more frequently. We tested these hypotheses by surveying HGT in four congeneric species of bdelloids from different habitats: two from permanent aquatic habitats and two from temporary aquatic habitats that desiccate regularly.', 'Transcriptomes of all four species contain many genes with a closer match to non-metazoan genes than to metazoan genes. Whole genome sequencing of one species confirmed the presence of these foreign genes in the genome. Nearly half of foreign genes are shared between all four species and an outgroup from another family, but many hundreds are unique to particular species, which indicates that HGT is ongoing. Using a dated phylogeny, we estimate an average of 12.8 gains versus 2.0 losses of foreign genes per million years. Consistent with the desiccation hypothesis, the level of HGT is higher in the species that experience regular desiccation events than those that do not. However, HGT still contributed hundreds of foreign genes to the species from permanently aquatic habitats. Foreign genes were mainly enzymes with various annotated functions that include catabolism of complex polysaccharides and stress responses. We found evidence of differential loss of ancestral foreign genes previously associated with desiccation protection in the two non-desiccating species.
Answer: Nearly half of foreign genes were acquired before the divergence of bdelloid families over 60 Mya. Nonetheless, HGT is ongoing in bdelloids and has contributed to putative functional differences among species. Variation among our study species is consistent with the hypothesis that desiccating habitats promote HGT.
[EX A]:
Is horizontal gene transfer in bdelloid rotifers ancient , ongoing and more frequent in species from desiccating habitats?