438 METABOLIC ABNORMALITIES, AUTOINTOXICATION 



may have been produced secondarily by the products of the 

 abnormal metabolism. 



While admitting the preponderating importance of toxic 

 organic substances as the cause of uremia, we cannot dismiss as 

 altogether unimportant the changes in osmotic pressure in the 

 blood and tissue fluids, even although it has been shown by 

 Strauss and others that there is no constant relation be- 

 tween the osmotic pressure of the blood and the uremic attack. 

 It still seems quite possible that the hyperosmotic condition of 

 the fluids in the brain is the determining factor in some uremic 

 attacks. Neither can we entirely dismiss the edema of the 

 brain and meninges that is associated with this hypertonicity, 

 from the possible factors in the production of uremia. The 

 " wet brain " of the uremic is too frequent an autopsy finding 

 to be without importance, and clinicians have repeatedly noted 

 a favorable effect from spinal puncture in uremia, following 

 the escape of a fluid under apparently abnormally high pressure. 1 



The Internal Secretion of the Kidney. Another possible 

 factor in uremia is the hypothetical internal secretion of the 

 kidney. Bradford, 2 through an extensive experimental study 

 of the effects of partial resection of the kidney tissue, found 

 that if three-quarters of the total kidney tissue be removed (in 

 dogs) death occurs with profound tissue wasting and asthenia, 

 which is associated with an elimination of more urea and water 

 than a normal animal passes with two complete kidneys. The 

 fragment of kidney left is able to excrete amounts of urea far 

 larger than those usually excreted, as is shown by giving the 

 animals considerable quantities of an exclusively meat diet. Of 

 particular importance is the fact that the amount of nitrogenous 

 extractives (non-proteid nitrogen) in the blood and tissues, especi- 

 ally the muscles, is much greater than in normal animals, even 

 when the nitrogen excretion is above normal ; which indicates 

 that loss of renal tissue results in excessive proteid katabolism, 

 and suggests that the kidneys have an important function in 

 regulating proteid metabolism through the production of an 

 internal secretion with inhibitory effect on metabolism. In 

 accordance with this, Yitzou 3 claims to have demonstrated that 

 the blood from the renal vein contains substances which decidedly 

 reduce the severity of uremia in experimental animals. If this 

 contention is true, there exists the possibility that in interstitial 

 nephritis the loss of renal tissue may cause a deficiency in an 



l See Willson, Jour. Amer. Med. Assoc., 1904 (43), 1019. 



2 Jour, of Physiol., 1899 (23), 415. 



3 Jour. Phys. et Path. Gen., 1901 (3), 901 and 926. 



