STUDY OF DISEASE 



certain cases, which will differentiate these two types of disturb- 

 ances and to show, for instance, that diabetic hyperglycemia is 

 a consequence chiefly of impaired glucose utilization, whereas 

 the hyperuricemia in certain types of gout is a consequence of 

 excessive production of uric acid. 



Such experiments are most securely conducted on the intact 

 animal, and indeed, in the case of gout, the experimenter is 

 restricted to man, since no analogous disease in experimental 

 animals is available. The reasons for this preference for the 

 intact animal lie in the fact that the disease process is itself a 

 disintegration of some phase of that highly integrated system 

 which is the organism as a whole. Any further disorganiza- 

 tion imposed by the experimenter will necessarily confuse the 

 picture and may obscure the primary disturbance which is due 

 to the disease itself. Furthermore, the normal constancy of 

 composition of the blood with respect to glucose, uric acid, al- 

 bumin, etc., of the subcutaneous tissues with respect to lipid, or 

 of the liver with respect to glycogen, fatty acids, or cholesterol 

 is a resultant of many processes occurring in many tissues. 

 The very separation of the several tissues may result in dis- 

 appearance of the abnormality of rate the explanation of which 

 is being sought. 



The foregoing argument must not be construed to mean 

 that only experimental results derived from the intact animal 

 are of use in the elucidation of disease processes. On the 

 contrary, all levels of biological disorganization have con- 

 tributed significantly to this body of knowledge. What is in- 

 tended is merely to point out that of such results as are secured 

 with isolated enzyme preparations or isolated tissues of diseased 

 animals, only those which are compatible with observations on 

 the intact diseased animal are of value in explaining the disease 

 process. 



The contributions of the several experimental approaches 

 may be exemplified by an analysis of the various abnormalities 

 which may influence the concentration of glucose in the blood. 

 Glucose enters the portal blood by intestinal absorption and since 



165 



