176 F. Dickens, G. E. Clock and P. McLean 



and reduced coenzymes would be expected to play an im- 

 portant part in the regulation of alternative pathways of 

 carbohydrate metabolism. In addition, certain metabolic 

 derangements such as occur, for example, in diabetes and 

 tumour formation might produce alterations in the steady- 

 state concentrations of the oxidized and reduced forms. 

 Table V incorporates results for liver from normal and alloxan 

 diabetic rats, from rats rendered hyperthyroid by thyroxine 

 injections (Clock and McLean, 19556) and for liver tumours 

 induced in DAB feeding (Clock and McLean, 1957). 



* Tissue adjacent to liver tumour. 



The DPN+/DPNH quotient is significantly lowered in 

 diabetes, due both to a fall in DPN+ and an increase in DPNH. 

 This lowered quotient may perhaps be a result of decreased 

 lipogenesis. However, on account of the multiplicity of 

 coenzyme-linked reactions and our present very incomplete 

 knowledge as to how these may be afPected in different 

 pathological conditions, it appears unwarranted to speculate 

 as to the exact cause of any observed change in this quotient. 

 The total TPN content per g. liver is not affected in diabetes, 

 but total DPN and TPN are both significantly reduced if 

 expressed on a whole liver basis. The above findings on 

 altered DPN+/DPNH+ quotients do not agree with those of 

 Helmreich and co-workers (1954) and Greenbaum and Gray- 

 more (1956). These two groups of workers, using the same 



