A quick question about scientific semantics regarding interaction of stimuli: I have two stimuli, A and B that induce quantifiable effect E. A is a drug and shows a dose-response curve, B is a cell-culture condition (e.g. 2d vs 3d) and therefore a binary categorical variable.
The effect of both stimuli together is less than the sum of the two separate effects (E.g. E|AB < (E|A +E|B) for relevant doses of A. How do I describe the interaction, as additive or as synergistic? My gut feeling would say additive, as the combined effect is lower than the sum but I'm not sure.
Which is the 'safest' formulation? Would you say it's additive until you can show synergism?
Put your numbers in Calcusyn software, it will calculate it for you. If the combination index (CI) is equal to 1, additive effect. CI
have you considered 'antagonism' or 'antagonistic'?
When you have a sum of two stimuli less than 'additive' value it can be considered antagonistic. If the sum of two values observed is the same as (theoretically) calculated (A+B), it is considered additive. If the sum of two values is more than expected (theoretical) value, it is synergism. If you google 'isobolography' you will get a lot more info
I think SG's reply covers the problem. But personally I would not call such "negative interaction" a synergism, at least not without adding "negative". Also, if you are a mathematician, you would definitely call the joint effect you descrtibe by the simple adjective 'subadditive.'
Thanks for all the replies. I hadn't heard the term 'subadditive' before, but that seems to be the exact word I'm looking for.
As you know synergism is increased activity obtained from two different
agent used combined than when they are used alone. Additive is the sum. for instance let as assume A = 2, B= 3. during synergy A+B = 8, additive A+B=5
I had this question too. I don't know about subadditive, not many people would know what that means. I think the more correct term is antagonistic https://en.wikipedia.org/wiki/Interaction#Biochemistry
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