TASK DEFINITION: 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.
PROBLEM: Context: To evaluate the effects of COX-1 and/or COX-2 inhibition in a model of chronic esophagitis in rabbits.', 'Both high- and low-grade esophagitis were induced in rabbits by the perfusion of acidified pepsin. Rabbits were treated with either a selective COX-2 inhibitor (DFU[3-(3-Fluorophenyl)-4-(4-Methanesulfonyl)-5,5-Dimethyl-5H-Furan-2-One];30 mg/Kg/day), a nonspecific COX inhibitor (indomethacin; 2 mg/Kg/day), or a COX-1 preferential inhibitor (piroxicam; 2 mg/Kg/12 h).', 'Prostaglandins are derived from COX-1 activity in the normal esophagus. Both low- and high-grade esophagitis are associated with a progressive increase of COX activity, which is partially dependent on the COX-2 isoform. DFU reduced muscosal damage in both models of esophagitis. However, indomethacin did not affect significantly mucosal damage, and piroxicam increased damage in low-grade esophagitis.\Question: Is selective COX-2 inhibition associated with decreased mucosal damage induced by acid and pepsin in rabbit esophagitis?

SOLUTION: COX-1 activity is constitutive in the rabbit esophageal mucosa, but both COX-2 and COX-1 activity are increased under the impact of acidified pepsin. Treatment with the COX-2 inhibitor DFU is associated with improvement of mucosal damage, which may have therapeutic implications.

PROBLEM: Context: Infection of human immunodeficiency virus (HIV) has been associated with several chronic diseases, including pulmonary artery hypertension and atherosclerosis. However, the underlying mechanisms of these vascular complications are largely unknown. The objective of this study was to test a novel hypothesis that HIV Nef, an accessory HIV protein, may directly affect endothelial functions and gene expression in pulmonary arteries.', 'Fresh porcine pulmonary artery rings and human pulmonary artery endothelial cells (HPAECs) were treated with HIV Nef for 24 h. With a myograph device, vasomotor function was determined with thromboxane A2 analog, U46619, for contraction, bradykinin, and sodium nitroprusside for relaxation. The expression of endothelial nitric oxide synthase (eNOS) was determined with real-time PCR and immunohistochemistry. Nitric oxide (NO) production was determined by Calorimetric Nitric Oxide Assay kit. Superoxide anion levels were detected with lucigenin-enhanced chemiluminescence assay and dihydroethidium (DHE) staining.', 'The endothelium-dependent vasorelaxation in response to bradykinin was significantly reduced in HIV Nef-treated porcine pulmonary artery rings in a concentration-dependent manner. In response to bradykinin (10(-8) mol/L), HIV Nef (10 ng/mL) significantly reduced vasorelaxation by 32% compared with untreated controls (P < 0.05). In addition, HIV Nef significantly decreased eNOS expression in the vessels and HPAECs. HIV Nef at 10 ng/mL significantly decreased NO production in HPAECs by 21% compared with controls (P < 0.05). Furthermore, HIV Nef significantly increased superoxide anion production in porcine pulmonary arteries and HPAECs compared with controls (P < 0.05). Consequently, Mn (III) tetrakis porphyrin, a superoxide dismutase mimic, effectively blocked HIV Nef-induced vasomotor dysfunction and superoxide anion production. The specificity of HIV Nef action was confirmed by anti-Nef antibody blocking and Nef heat inactivation.\Question: Does hIV Nef protein cause endothelial dysfunction in porcine pulmonary arteries and human pulmonary artery endothelial cells?

SOLUTION: HIV Nef protein significantly decreases endothelium-dependent vasorelaxation in porcine pulmonary arteries. It also reduces eNOS expression and induces oxidative stress in both porcine pulmonary arteries and HPAECs. This study demonstrates a new mechanism of HIV Nef, which causes endothelial dysfunction and may contribute to the human pulmonary artery disease in HIV-infected patients.

PROBLEM: Context: Growth factor therapy provides a therapeutic alternative for "no option" patients with coronary disease. Fibroblast Growth Factor-2 (FGF-2) predominantly stimulates angiogenesis, the growth of new capillaries, whereas Monocyte Chemoattractant Protein-1 (MCP-1) is considered an arteriogenic agent. We hypothesised a synergetic effect of FGF-2 and MCP-1 in ischemic myocardium.', 'A severe coronary stenosis was created in pigs. After one week, chronic ischemia was confirmed by angiography, echocardiography, reduced ejection fraction, and increase of marker enzymes. FGF-2, MCP-1, both, or vector only were then injected intramyocardially as plasmid DNA in the impaired area. Regional contractility and number of capillaries and arterial vessels were evaluated after three months.', 'FGF-2, FGF-2+MCP-1, and vector, but not MCP-1 alone improved regional contractility at rest, whereas only FGF-2 alone ameliorated function under stress conditions. Angiogenesis in the ischemic area was stimulated by FGF-2 compared to MCP-1. In contrast, MCP-1 induced arteriogenesis relative to FGF-2.\Question: Does improvement of contractility accompany angiogenesis rather than arteriogenesis in chronic myocardial ischemia?

SOLUTION:
Differences for vessel growth and regional function were apparent between FGF-2 and MCP-1. This contrast could allow the speculation that development of a flow reserve in chronically ischemic myocardium is linked to angiogenesis rather than to arteriogenesis. No additional benefits were seen following combined therapy.