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: 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 output: 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.
Q: Abstract: In search of a practical biochemical test that will reflect hepatic steatosis, we assessed the significance of serum cholinesterase activity in 48 patients with nonalcoholic fatty liver, 16 obese subjects without fatty liver, 30 cases of chronic persistent hepatitis, 38 cases of chronic active hepatitis, and 20 cases of liver cirrhosis. Increased cholinesterase activity was observed in nonobese as well as obese patients with fatty liver, whereas obese subjects without fatty liver showed levels in the upper normal range. When we set a cutoff level above the upper normal limit, half of the patients with fatty liver showed values above it, with only a few overlaps with other patients. When obese patients with fatty liver took a low-caloric diet, cholinesterase activity decreased, clearly reflecting improvement of hepatic steatosis. Thus, measurement of cholinesterase activity is of diagnostic value and an alternative to computed tomography in hepatic steatosis, and will provide a practical measure for the assessment of effects during follow-up.
A:
Cholinesterases