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: Recent evidence shows tetracyclines have anticollagenolytic activity that may be clinically effective in disease treatment. This led us to use systemic tetracycline (oral tetracycline hydrochloride 1 g daily divided into 4 doses) as adjunctive therapy in treating 18 patients with persistent corneal epithelial defects. Fourteen of 18 patients healed their defects; within 48 hours (9 patients) and within two weeks (the other 5 responding patients). Two patients showed no effect and two showed disease progression.
Example Output: Adolescence

Example Input: Abstract: Forty-three of 79 patients treated for clinically metastatic germ cell cancer survived for a median of 66 months (range, 52-83). In patients without previous chemotherapy the 5-year survival rate was 69%, whereas only 32% of patients with prior chemotherapy survived for 5 years. Limited disease, complete clinical response, histopathologically proven postchemotherapy tumor necrosis or complete resectability of a posttreatment mature teratoma indicated a favorable prognosis in patients without prior chemotherapy. Only 20% to 30% of the patients with less than a clinical complete response or with posttreatment residual malignant tumor can be salvaged by second line therapy. Posttreatment mature teratoma should be resected completely whenever possible, as this condition may lead to reactivation of the malignancy even after several years. Raynaud-like phenomena and/or gastrointestinal problems are the main long-term sequel (10%-15%) after modern multimodality treatment of advanced germ cell cancer (fertility-related problems are not considered here). In the majority of surviving patients, the lifestyle seems unaffected by the previous intensive treatment, evaluated about 5 years after discontinuation of all therapy.
Example Output: Antineoplastic Agents, Combined

Example Input: Abstract: We have isolated a syngeneic monoclonal antibody (HepSS-1) reactive to a murine methylcholanthrene-induced fibrosarcoma, Meth-A. HepSS-1 also bound to a wide variety of established and fresh normal cells derived from not only mice but also other species such as human, monkey, rat, hamster, and chicken. Immunoprecipitation of surface iodinated Meth-A cell extract with HepSS-1, as well as Sepharose 4B gel chromatography of Meth-A cell extract and detection of antigens recognized by HepSS-1 by a sandwich-type radioimmunoassay revealed that the HepSS-1 antigens were composed of several molecular species, with one as large as approximately 10(6) daltons. The following evidence indicates that HepSS-1 specifically recognizes an epitope present in heparan sulfate glycosaminoglycan (HS-GAG). First, treatment of Meth-A cells with heparitinase or heparinase, but not with chondroitinase ABC or hyaluronidase, resulted in the loss of HepSS-1 binding. Second, HS-GAG but not seven other types of GAG (hyaluronic acid, heparin, chondroitin, chondroitin 4-sulfate, chondroitin 6-sulfate, dermatan sulfate, and keratan sulfate) inhibited HepSS-1 binding to Meth-A cells. Third, HepSS-1 bound with HS-GAG but not with the seven other types of GAG. From the binding analysis of HepSS-1 to various modified HS-GAG and whale omega-heparin, it is additionally suggested that HepSS-1 recognizes an epitope closely related to O-sulfated and N-acetylated glucosamine. We found that NIH 3T3 cells expressed more HepSS-1 epitopes at a low cell density than at confluency and in G2 + M than in G1, whereas NIH 3T3 cells transformed with Kirsten-ras oncogene or SV-40 expressed high levels of HepSS-1 epitopes and ceased to show the density-dependent change in the amount of HepSS-1 epitopes. These observations were also reproduced by using NIH 3T3 cells transformed with a temperature sensitive Kirsten murine sarcoma virus maintained at permissive and non-permissive temperatures. Thus HepSS-1 is a first monoclonal antibody to HS-GAG and seems to be useful to elucidate changes in cell surface HS-GAG in normal cell growth and cell transformation.
Example Output:
Animal