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: A series of monoclonal antibodies (mAb) was raised in mice against Schistosoma mansoni, which recognized a carbohydrate determinant on a major Mr greater than 200,000 schistosomulum surface antigen. These mAb cross-reacted with the surface of cercariae and miracidia and with schistosomula of S. haematobium and S. bovis. Other mAb were generated that only recognized a Mr 20,000 schistosomulum surface antigen; they did not cross-react with eggs or miracidia and were species specific. The anti-Mr 20,000 mAb of the IgG1 isotype exhibited high levels of complement-dependent cytotoxicity to schistosomula in vitro. IgM mAb that recognized carbohydrate epitopes of the Mr greater than 200,000 surface antigen blocked the lethal activity of the anti-Mr 20,000 mAb. The IgM anti-Mr greater than 200,000 mAb also reduced complement-dependent cytotoxicity of serum from mice vaccinated with irradiated cercariae.
Example Output: Animal

Example Input: Abstract: From 1974 to 1984, 321 tubal pregnancies were treated conservatively with laparoscopic techniques. Fifteen cases (4.8%) required a subsequent laparotomy or second laparoscopic procedure because of retained trophoblastic tissue. Of 118 patients desiring subsequent pregnancy, 76 had an intrauterine pregnancy (64.4%) and 26 had a second ectopic pregnancy (22%). Eleven of 24 (45.8%) women attempting conception following conservative laparoscopic removal of an ectopic gestation from the sole remaining fallopian tube established an intrauterine pregnancy. In this same group, seven patients (29.2%) had a second ectopic pregnancy. The fertility results were also analyzed according to the previous history. The postoperative intrauterine pregnancy rate was 85.5% among 62 patients without a history of infertility (group I), compared with 41.1% among 56 patients with a history of infertility or a previous ectopic pregnancy (group II). The subsequent ectopic pregnancy rate in group I was 16.1% versus 28.6% in group II. This large series clearly demonstrates the relative safety and efficacy of conservative laparoscopic treatment of tubal pregnancies.
Example Output: Adolescence

Example Input: Abstract: Rat liver microsomal insulin-like growth factor-II (IGF-II) receptor has been purified to homogeneity using a single step affinity chromatographic procedure on agarose-IGF-II with elution at pH 4. Determined by either IGF-II binding or a direct RIA for receptor, purification of 2000-fold was obtained. The mean recovery was 28% for five such preparations. Sodium dodecyl sulfate-electrophoresis and autoradiography of purified receptor, radioiodinated receptor, and affinity-labeled receptor all indicated a molecular mass of approximately 250K. Scatchard analysis of IGF-II binding to purified receptor, solubilized microsomal membranes, or plasma membranes showed a single class of binding site with an affinity constant of 6 X 10(10) liter/mol in all cases. Potent antibodies to the purified receptor were raised in rabbits, capable of inhibiting 50% of IGF-II binding at dilutions of 1:170,000 and also of fully precipitating IGF-II-prelabeled receptor at 1:50,000. Both types of antibodies reacted with IGF-II receptors in rat adipose tissue, brain, heart, kidney, lung, and spleen. However, little cross-reactivity was seen with other species. Comparison of the ability of receptor antibodies to inhibit IGF-II binding to microsomal and plasma membranes indicated a specific immunological difference between the IGF-II receptors in the two membrane preparations.
Example Output:
Animal