SECONDARY BACTERIAL INFECTION IN MICE 



parts housed in groups have only the stress of cold, plus the stress 

 of challenge. If you talk in terms of how many stresses are actually 

 applied to the experimental animal, it may be a quantitative thing 

 that you could put your finger on. Let's say it is the function 

 of the total stress as applied to the organism, and I think this 

 can be tested by taking a singly- caged animal and placing it 

 at room temperature in a cage which has an electrical charge 

 to it, then you have the three stresses. You can induce as many 

 more stresses as you see fit. 



VIERECK: Dr. Miya, do I understand you to say that isolation 

 is a stress? Usually, in theories of population dynamics, den- 

 sities, as they get greater, are considered to be more stress- 

 ful. I know you are dealing with animals in the cold, but it sounded 

 like you considered isolation, per se, without cold, to be a stress 

 to an animal. What is your evidence? 



MIYA: Well, I don't have any for an animal, but I think in terms 

 of human beings. 



VIERECK: High population density has been studied as a stress 

 in humans. 



MIYA: I think I could survive longer in Alaska with one other 

 person to talk to than just by myself. 



MITCHELL: Mice are happy only when they're alone. 



MIRAGLIA: I don't wish to minimize the psychological effect, 

 but we have conducted experiments with both group- housed and 

 isolated animals at room temperature, and the LDcq is ^^^ ^.l- 

 tered, so using this criteria alone, which, to be sure, is not 

 enough by itself, there is no psychological effect of isolation. 



REINHARD: It seems to me that the investigators here are 

 facing the extreme difficulty of separating the effect of one type 

 of flora from another. And you have to go to extreme kinds of 

 manipulations, like feeding hydrochloric acid to rid a beast of 

 one or other organisms. I wonder, in this day and age of germ- 

 free animals, whether the latter would not be more suitable 



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