Given the task definition, example input & output, solve the new input case.
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: Abstract: Some patients converted from ventricular fibrillation to organized rhythms by defibrillation - trained ambulance technicians(EMT - Ds) will refibrillate before hospital arrival.The authors analyzed 271 cases of ventricular fibrillation managed by EMT - Ds working without paramedic back - up.Of 111 patients initially converted to organized rhythms, 19(17 % ) refibrillated, 11(58 % ) of whom were reconverted to perfusing rhythms, including nine of 11(82 % ) who had spontaneous pulses prior to refibrillation.Among patients initially converted to organized rhythms, hospital admission rates were lower for patients who refibrillated than for patients who did not(53 % versus 76 % , P = NS), although discharge rates were virtually identical(37 % and 35 % , respectively).Scene - to - hospital transport times were not predictively associated with either the frequency of refibrillation or patient outcome.Defibrillation - trained EMTs can effectively manage refibrillation with additional shocks and are not at a significant disadvantage when paramedic back - up is not available.
Output: Ventricular Fibrillation
This term is directly present in the abstract and it is one of the main topic in it. So can be chosen as the medical subject heading.

New input case for you: Abstract: We developed a highly sensitive and specific assay for hCG using monoclonal antibodies (Mabs) directed against a 37-amino acid synthetic polypeptide analogous to the carboxyl-terminus (CTP) of beta hCG. Five antibodies that varied by either their affinity for beta hCG or their specificity for epitopes on CTP were investigated. To measure hormone levels, we used as the radiolabeled indicator an alpha-subunit-reactive Mab. The monoclonal-immunoradiometric assay had a lower limit of sensitivity of 0.05 ng/ml. Serum levels of hCG or hCG-like material with CTP structure were measured in 229 healthy blood donors; 1.1% of healthy men and 4.6% of nonpregnant women younger than 50 yr had serum values varying between 0.05 and 0.23 ng/ml. Moreover, 6 to 7 healthy women older than 50 yr had detectable levels in the 0.05-0.20 ng/ml range. To study the disappearance rates in normal women, we followed serum hCG serum levels of 6 women who had previously received a single im injection of the hormone. These individuals failed to develop a pregnancy after in vitro fertilization; hCG declined from 0.5 to 0.05 ng/ml within 2 weeks. These results were in contrast to the findings in 12 patients with hCG-producing tumors. In 9 patients without any evidence of recurrent disease, hCG levels became undetectable within 5 months. However, 3 others had levels consistently above 0.05 but below 0.5 ng/ml. In 2 of these three patients, subsequent increasing hCG levels were associated with tumor recurrence. We conclude that this hCG assay based on both anti-peptide and anti-hCG Mabs may be useful in tumor monitoring.
Output:
Adult