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.
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Question: Context: To study the pulmonary effects of aspirating a mixture of sucralfate in water and sucralfate in hydrochloric acid in an animal model of aspiration pneumonia.', 'Prospective, randomized, controlled study with repeated measures.', 'University research laboratory.', 'Thirty-two in situ, isolated, blood perfused porcine lung preparations.', 'Five control preparations received no aspiration. Twenty-seven preparations received a standard aspiration of 1.5 mL/kg body of a) distilled water (n = 5), b) sucralfate in distilled water (n = 8), c) 1/10 normal hydrochloric acid (n = 6), and d) mixture of sucralfate in distilled water and hydrochloric acid (n = 8).', 'The pH measurements were made of all aspirates. Lung weight, airway pressures, and pulmonary artery pressures were continuously monitored before and for 4 hrs after aspiration. Lung wet/dry weight ratio was measured at the completion of the study.', 'The pH of sucralfate mixed with distilled water was 4.9, pH of 1/10 normal hydrochloric acid was 1.0, and pH of equal volumes of a sucralfate-water suspension mixed with hydrochloric acid was 1.5. Airway pressures and pulmonary arterial pressures increased in all aspirate groups over time compared with those values of control lungs. Control lungs gained 18 +/- 3 (SEM) g over 4 hrs and the wet/dry ratio was 4.951 +/- 0.310. Lungs aspirating distilled water gained 147 +/- 49 g and the wet/dry ratio was 5.198 +/- 0.120. Lungs aspirating sucralfate and distilled water increased their weight by 109 +/- 30 g and the wet/dry ratio was 5.380 +/- 0.076. Lungs aspirating a suspension of sucralfate and water and hydrochloric acid were similar to lungs aspirating hydrochloric acid alone with weight increases of 265 +/- 30 g and 346 +/- 81 g, and the wet/dry ratio of 7.011 +/- 0.273 and 7.230 +/- 0.390, respectively.\Question: Does sucralfate reduce the risk of acid aspiration pneumonitis?

Answer: Sucralfate has minimal acid buffering effect. Aspiration of sucralfate mixed with distilled water causes lung edema similar to aspiration of water alone. Aspiration of a sucralfate-water suspension mixed with hydrochloric acid causes severe lung edema. These results suggest that patients given sucralfate prophylaxis for stress ulceration are at risk for acid aspiration.


Question: Context: Aging is associated with reduced secretion of, and down-regulation of receptors for, progesterone (P); yet, P's effects when administered to younger and older animals have not been systematically investigated. Some of P's antianxiety effects may be due to its conversion to 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP) and its subsequent actions as a positive modulator at GABAA receptor complexes (GBRs).", 'We investigated whether P administration can decrease anxiety behavior of progestin receptor (PR) knockout (PRKO) or wild-type control mice.', 'P (10 mg/kg) or vehicle (propylene glycol) were administered subcutaneously to intact, female or male wild-type or PRKO mice that were either 9-12 or 18-24 months of age. Behavior in tasks that assess spontaneous activity (activity monitor and roto-rod), free exploration of a novel environment (open field, elevated plus maze, and elevated zero maze), and conflict behavior (mirror chamber, dark-light transition, and punished drinking) were examined 1 h after injection.', 'P significantly decreased anxiety behavior of both PRKO and wild-type mice. P did not alter motor behavior but increased central entries in the open field, time in the open quadrants of the elevated zero maze, time in the mirrored chamber, time in the light compartment of the dark-light transition, and punished drinking in young and old mice. P-administered mice had higher levels of hippocampal 3alpha,5alpha-THP and GABA-stimulated chloride flux than did vehicle-administered PRKO or wild-type mice.\Question: Do progesterone 's effects to reduce anxiety behavior of aged mice require actions via intracellular progestin receptors?

Answer: The effects of P to decrease anxiety behavior of younger and older mice do not require classic PRs and may involve actions of 3alpha,5alpha-THP at GBRs.


Question: Context: Tracheal immunogenicity has been controversial. Although replacement of allotracheal epithelia by the host epithelia has been reported in rat orthotopic tracheal grafting, the immunological effect of epithelial replacement is still uncertain.', 'We performed orthotopic tracheal grafting of nine cartilage rings in the following groups: 1, Lewis --> Lewis (n = 30); 2, ACI --> DA (n = 25); 3, Lewis --> F344 (n = 23); 4-A, DA --> Lewis (n = 41); 4-B, DA --> Lewis with tacrolimus therapy (1 mg/kg/d for 10 days) starting from the day of the operation (n = 31); 4-C, retransplantation of DA allografts to secondary naive Lewis rats 10 or 15 days after primary grafting (n = 11); 4-D, DA --> Lewis with tacrolimus therapy starting from postoperative day 10 (n = 6). Survival times and histopathology were assessed. Epithelial replacement was evaluated by immunohistochemistry.', 'All rats survived in groups 1, 2, and 3. Even in the fully histoincompatible group 4-A, survival ratio on day 120 was 15%. Epithelial replacement was in progress on day 10 in this group. However, all tacrolimus-treated rats died by day 54 and epithelial replacement did not occur on days 30 and 50 in group 4-B. In group 4-C, retransplantation after complete epithelial replacement increased the long-surviving rats. In group 4-D, all rats receiving tacrolimus therapy after complete epithelial replacement survived over 120 days.\Question: Does complete replacement of tracheal epithelia by the host promote spontaneous acceptance of orthotopic tracheal allografts in rats?

Answer:
These results suggest that complete replacement of tracheal epithelia by the host promotes spontaneous acceptance of orthotopic tracheal allografts in rats.