instruction:
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.
question:
Context: To evaluate whether P2X3 receptors (P2X3R) are expressed in the bladder urothelium and to determine their possible function in modulating purinergic detrusor contractions in the rat urinary bladder.', 'The expression of urothelial receptors was determined using conventional immunohistochemistry in bladders from normal Sprague-Dawley rats. The urothelial layer was removed by incubation with protamine, and disruption of the urothelium was confirmed using haematoxylin and eosin staining on bladder sections. Open cystometry was used to determine the effects of both urothelial removal as well as intravesical application of a specific P2X3R antagonist on bladder properties from intact and protamine-treated rats. Isometric contractile responses to potassium chloride (KCl) depolarization, electrical field stimulation (EFS) or chemical P2X activation were determined in normal and urothelium-denuded bladder strips, with and without application of the P2X3R antagonist.', 'Immunohistochemical staining showed high expression of P2X3R in the medial and basal layers of the urothelium. Removal of the urothelial layer disturbed normal bladder performance in vivo and eliminated the effects of the P2X3R antagonist on increasing the contractile interval and reducing the amplitude of voiding contractions. Removal of the urothelium did not affect bladder strip contractile responses to KCl depolarization or EFS. Pharmacological inhibition of P2X3R prevented desensitization to P2X-mediated detrusor muscle contractions during EFS only in the strips with an intact urothelium. A concentration-dependent, specific inhibition of P2X3R also prevented desensitization of purinergic contractile responses in intact bladder strips.
Answer: In the rat bladder, medial and basal urothelial cells express P2X3R, and specific inhibition of the receptor leads to a more hyporeflexive bladder condition. This pathway may involve P2X3R driving a paracrine amplification of ATP released from umbrella cells to increase afferent transmission in the sub-urothelial sensory plexus and desensitization of P2X1-mediated purinergic detrusor contractions.
answer:
Does inhibition of urothelial P2X3 receptors prevent desensitization of purinergic detrusor contractions in the rat bladder?


question:
Context: To assessdoctor's knowledge on the relevance of the problem of sleep disorders, methods of their diagnosis and treatment.", 'The survey was conducted among90physicians of different the rapeuticspecialties of Kazan medical institutions.', 'The doctors believe that main causes of sleep disorders are stressors (20%), depression (13%), neurosis (13%), chronic diseases (13%), asthenia (10%), pain (10%). An analysis of treatment prescribed to patients with sleep disorders revealed large differences.
Answer: Physicians are not well informed about the problems of sleep disorders, have a small idea of the methods of sleepresearch and drugs for their treatment as well as of a sequence of operations that should be used to resolve this problem.
answer:
Do [ What do the doctors of different specialties know about sleep disorders and their treatment ]?


question:
Context: Drug resistance in breast cancer is the major obstacle to effective treatment with chemotherapy. While upregulation of multidrug resistance genes is an important component of drug resistance mechanisms in vitro, their clinical relevance remains to be determined. Therefore, identifying pathways that could be targeted in the clinic to eliminate anthracycline-resistant breast cancer remains a major challenge.', 'We generated paired native and epirubicin-resistant MDA-MB-231, MCF7, SKBR3 and ZR-75-1 epirubicin-resistant breast cancer cell lines to identify pathways contributing to anthracycline resistance. Native cell lines were exposed to increasing concentrations of epirubicin until resistant cells were generated. To identify mechanisms driving epirubicin resistance, we used a complementary approach including gene expression analyses to identify molecular pathways involved in resistance, and small-molecule inhibitors to reverse resistance. In addition, we tested its clinical relevance in a BR9601 adjuvant clinical trial.', 'Characterisation of epirubicin-resistant cells revealed that they were cross-resistant to doxorubicin and SN-38 and had alterations in apoptosis and cell-cycle profiles. Gene expression analysis identified deregulation of histone H2A and H2B genes in all four cell lines. Histone deacetylase small-molecule inhibitors reversed resistance and were cytotoxic for epirubicin-resistant cell lines, confirming that histone pathways are associated with epirubicin resistance. Gene expression of a novel 18-gene histone pathway module analysis of the BR9601 adjuvant clinical trial revealed that patients with low expression of the 18-gene histone module benefited from anthracycline treatment more than those with high expression (hazard ratio 0.35, 95\xa0% confidence interval 0.13-0.96, p\u2009=\u20090.042).
Answer: This study revealed a key pathway that contributes to anthracycline resistance and established model systems for investigating drug resistance in all four major breast cancer subtypes. As the histone modification can be targeted with small-molecule inhibitors, it represents a possible means of reversing clinical anthracycline resistance.
answer:

Is downregulation of histone H2A and H2B pathways associated with anthracycline sensitivity in breast cancer?