In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
--------
Question: Context: Ischemic postconditioning protects the reperfused heart from infarction, and this protection is dependent on the occupancy of adenosine receptors. We further explored the role of adenosine receptors in this salvage.', 'In situ rabbit hearts underwent 30 min of regional ischemia and 3 h of reperfusion, and postconditioning was effected with four cycles of 30-s reperfusion/30-s coronary artery occlusion at the end of ischemia.', "Postconditioning reduced infarct size from 40.2+/-3.4% of the risk zone in untreated hearts to 15.5+/-2.5%. Protection by postconditioning was blocked by either the non-selective adenosine receptor blocker 8-p-(sulfophenyl)theophylline or the A2b-selective antagonist MRS 1754, injected intravenously 5 min before reperfusion. The protein kinase C (PKC) antagonist chelerythrine also aborted postconditioning's salvage, indicating a PKC-dependent mechanism. Neither the A1-selective antagonist 8-cyclopentyl-1,3-dipropylxanthine nor the A2a-selective antagonist 8-(13-chlorostyryl)caffeine had an effect on protection. The non-selective but A2b-potent adenosine agonist 5'-(N-ethylcarboxamido)adenosine (NECA) infused from 5 min before to 1h after reperfusion mimicked postconditioning's effect on infarct size (17.2+/-2.7% infarction) and MRS 1754 blocked the NECA-induced cardioprotection, confirming that A2b activation was protective. The PKC activator phorbol 12-myristate 13-acetate delivered just before reperfusion also duplicated the protective effect of postconditioning (16.3+/-4.1% infarction), and co-administration of the PKC antagonist chelerythrine aborted PMA's protection, confirming that the protection was the result of PKC activation. NECA's protective effect was not affected by chelerythrine, but rather MRS 1754 blocked PMA's salutary effect (42.8+/-1.0% infarction), suggesting that the A2b receptor's effect is under control of PKC. Finally, wortmannin, a blocker of phosphatidylinositol 3-kinase, also abrogated protection by PMA.\Question: Does postconditioning protect rabbit hearts through a protein kinase C-adenosine A2b receptor cascade?

Answer: Salvage of ischemic myocardium by postconditioning is dependent on activation of A2b receptors, which in turn depends on activation of PKC. It is still unclear why PKC activation is required to make the heart's adenosine become protective.

Question: Context: CTLA4IgG that binds to B7 effectively inhibits the signaling of CD28/B7 pathway and induces antigen-specific T-cell unresponsiveness in vitro and in vivo. We examined whether the development of obliterative bronchiolitis in a murine heterotopic airway transplantation model is T cell dependent and whether CTLA4IgG abrogates the development of obliterative bronchiolitis.', 'Tracheae with main bronchi from C3H/He (H2k), BALB/C (H2d), or C57BL/6 (H2b) mice were transplanted heterotopically into subcutaneous pockets on the backs of BALB/C or BALB/C nu/nu mice on day 0. Recipient mice were untreated or intraperitoneally treated with either CTLA4IgG or human IgG with different time and dose schedules.', 'The development of obliterative bronchiolitis, which leads to luminal obliteration by fibrous tissue in a murine heterotopic airway transplantation model, was T cell dependent and the development of obliterative bronchiolitis was significantly abrogated by the CTLA4IgG treatment. However, the normal ciliated columnar respiratory epithelial cells in allografts were lost and replaced by flattened attenuated epithelial cells even after the CTLA4IgG treatment. We further demonstrated that CTLA4IgG treatment did not result in the induction of donor-specific unresponsiveness.\Question: Does blocking the CD28-B7 T-cell costimulatory pathway abrogate the development of obliterative bronchiolitis in a murine heterotopic airway model?

Answer: We demonstrated that the development of obliterative bronchiolitis in a murine heterotopic airway model involves both CD28/B7-dependent and -independent processes. The luminal obliteration by fibrous tissue is clearly CD28/B7 dependent and can be inhibited by CTLA4IgG. The luminal obliteration of allografted trachea by fibrous tissues and the loss of ciliated columnar respiratory epithelial cells represent distinct disease processes.

Question: Context: Increased serum hepcidin has been reported in patients receiving chronic hemodialysis, and hypothesized to contribute to the alterations of iron metabolism of end-stage renal disease. However, no quantitative assessment is available to date; the clinical determinants are still under definition; and the role of genetic factors, namely HFE mutations, has not yet been evaluated. The aim of this study was to quantitatively assess serum hepcidin-25 in hemodialysis patients versus controls, and analyze the relationship between hepcidin, iron indices, HFE genotype, and erythropoietic parameters.', 'Sixty-five hemodialysis patients and 57 healthy controls were considered. Hepcidin-25 was evaluated by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, HFE genotype by restriction analysis.', 'Serum hepcidin-25 was higher in hemodialysis patients compared with controls. In patients, hepcidin-25 correlated positively with ferritin and C reactive protein, and negatively with serum iron after adjustment for confounders. Hepcidin/ferritin ratio was lower in patients with (n = 25) than in those without (n = 40) HFE mutations. At multivariate analysis, hepcidin-25 was independently associated with ferritin and HFE status. In a subgroup of 22 "stable" patients, i.e., with Hb levels on target, normal CRP levels, and absence of complications for at least 1 yr, hepcidin-25 was negatively correlated with Hb levels independently of confounders.\Question: Do hFE mutations modulate the effect of iron on serum hepcidin-25 in chronic hemodialysis patients?

Answer:
Serum hepcidin-25 is increased in hemodialysis patients, regulated by iron stores and inflammation, and relatively reduced in subjects carrying frequent HFE mutations. Hepcidin-25 may contribute to the pathogenesis of anemia by decreasing iron availability.