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.

Q: Abstract: Severe aortic regurgitation developed in three patients after aortic valve replacement within six months due to long sutures prolapsing across the "annulus" of Bjork-Shiley prosthesis. At reoperation the offending sutures were trimmed or tucked back to the aortic wall to eliminate aortic regurgitation. Prolapse of unravelled knots may be the likely cause. Everting the sewing skirt during the first replacement may prevent this complication.

A: Aortic Valve
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Q: Abstract: The effect of indomethacin gel on UVB and UVC erythema was assessed objectively using a reflectance instrument. When indomethacin was applied immediately after irradiation, UVR (ultraviolet radiation) dose-dependent suppression of erythema was demonstrated for both wavelengths until 36 h after irradiation when both indomethacin and control gel base-treated sites were equally erythematous. Suppression of erythema also occurred when application of indomethacin was delayed until 24 h after irradiation, showing that for both wavelengths prostaglandin synthesis remains increased throughout this period. The degree of suppression at any time, however, was no greater than that achieved by a single application immediately after irradiation, indicating that the eventual equal erythema of indomethacin and gel base-treated sites was not due to tachyphylaxis or inadequate dosage. Construction of dose-response curves for the indomethacin-responsive and indomethacin-unresponsive components of erythema shows that in human skin the difference in erythemal response to UVB and UVC radiation is not due to the formation of different mediators at these wavelengths.

A: Administration, Topical
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Q: Abstract: Preoperative evaluation of parotid tumors still poses difficult problems for the head and neck surgeon. The complex anatomy of the parotid space leads to difficulty in localizing these tumors. In addition, physical examination will rarely determine whether a parotid lesion is benign or malignant. High resolution CT scanning with contrast and fine needle aspiration can provide enough preoperative information to enable the surgeon to counsel his patient concerning possible risks and the extent of surgery that may be indicated. We are able to determine tumor location, multiple or bilateral masses, associated adenopathy, and often specific tumor histology. Forty-two parotid aspirates and 26 CT scans were reviewed and correlated with their postoperative pathology specimen. Parotid aspiration cytology was found to be a highly accurate and safe procedure for preoperative determination of parotid pathology. However, the CT scan was specific only in defining the anatomic localization and extent of a parotid mass.

A:
Biopsy, Needle
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