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.

Example Input: Abstract: In order to perform quantitative in vitro and clinical studies on the removal of Al by the combined therapy of DFO administration and HD, an HPLC system for measuring DFO was established and a leaky membrane with enhanced permeability to middle molecular substances was developed. The DFO infusion caused rises in plasma Al levels (regarded as indicating the elution of accumulated Al) in patients undergoing HD. Plasma levels increased most in long-term patients and those with bone pain. Examination of Al clearances demonstrated that this increased plasma Al content passed through HD membranes at levels of more than 80 micrograms/l, and that the leaky membrane was more effective for removal of Al as well as DFO than the conventional one. Although a 1:1 complex between DFO and Al in an aqueous solution was confirmed, the formation of Al-rich complexes in vivo was suggested. It is concluded that Al-DFO complex formed in vivo can be effectively removed across the leaky membrane.
Example Output: Aluminum

Example Input: Abstract: Diarrhea and a small bowel lesion similar to that reported in celiac sprue were observed in a patient who had been taking sulindac. Symptoms and biopsy abnormalities resolved completely after discontinuation of the medication and promptly recurred upon its re-administration. This report emphasizes the need to consider possible drug-related small bowel disease in the growing list of causes of the "flat" small intestinal mucosal lesion.
Example Output: Backache

Example Input: Abstract: This article reports on the findings of a study of medical care expenditures of persons with acquired immunodeficiency syndrome (AIDS) treated at San Francisco General Hospital in 1984. We found that mean charges per AIDS hospital admission were $9024, mean charges of patients with AIDS who received all their hospital inpatient and outpatient care at San Francisco General Hospital in 1984 ranged from $7026 to $23,425, and mean lifetime inpatient charges of patients with AIDS who died and who had received all their inpatient care at the hospital were $27,571. These latter charges were considerably lower than previously published estimates of lifetime direct medical care costs of patients with AIDS, and the possible reasons for the differences include much lower lifetime use of hospital services and somewhat lower cost per hospital day.
Example Output:
Acquired Immunodeficiency Syndrome