instruction:
Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
question:
Abstract: Endomyocardial biopsy is most frequently used to establish a definitive diagnosis of myocarditis, especially since this disorder has been treated with immunosuppressive therapy. Recent diagnostic criteria (the "Dallas Classification") are reviewed, and pitfalls and limitations are discussed.
answer:
Biopsy

question:
Abstract: Over a 1-year period, rigid ureteroscopy has been used to retrieve ureteric calculi in 120 patients. The technical details, causes of failure and the complications are described. An initial success rate of 78% was obtained. It was concluded that ureteroscopy should replace blind procedures for the extraction of ureteric stones.
answer:
Adult

question:
Abstract: Sixteen adult subjects with asthma in a clinical steady state were studied. On day 1, after baseline spirometry, they underwent four histamine inhalation tests with functional recovery between each test. The provocative concentration causing a 20% fall in FEV1 (PC20) was obtained after each test. On days 2, 3, and 4, after baseline spirometry, active and placebo ascorbic acid (2 gm) was administered orally, double-blind, according to a 4.3.1 two-treatment crossover study design. One hour later, spirometry was performed, and PC20 was reassessed. We found no significant changes in FEV1 and FVC after ascorbic acid as compared with placebo administration. There was no difference between PC20 on days 2, 3, and 4 and by standardizing for the four PC20 results obtained on day 1. We conclude that ascorbic acid has no acute bronchodilator effect and does not alter bronchial responsiveness to histamine in subjects with asthma.
answer:
Adult