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.
Example solution: Ventricular Fibrillation
Example explanation: 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.

Problem: Abstract: The importance of cell-mediated immunity in cat-scratch disease (CSD) is suggested by the positive skin test reactions and granulomatous histopathology noted in patients with this disease. However, an earlier investigation found that lymphocytes from patients with CSD and control subjects were equally unresponsive in vitro to cat-scratch antigen. In contrast, we found that 16 patients with CSD had significantly increased lymphocyte transformation responses to cat-scratch antigen when patients were compared to control subjects. This cell-mediated immune response may be directed against nonviable bacteria in the involved lymph nodes and may be the major mechanism responsible for the granulomatous reaction and clinical features of CSD.

Solution: Adolescence