104 The Chemistry of the Injured Cell 



or descending tract degeneration. The commonest chronic type of 

 demyelinating disease is disseminated or multiple sclerosis. No 

 general agreement about the true nature of demyelinating pro- 

 cesses exists and the suggested causes include a variety of micro- 

 organisms, viruses, deficiencies and intoxications and injuries 

 (McAlpine, Compston and Lumsden, 1955) . Demyelination has 

 been produced in experimental animals by chemical agents such 

 as carbon monoxide, potassium and sodium azide, by various 

 toxins such as ergot, bee venom, tetanus toxin, organic phosphorus 

 compounds and by homologous brain suspensions emulsified with 

 the heat-killed acid-fast bacilli (Freund adjuvants) . Demyeli- 

 nating diseases of lambs (Swayback) are in some way related to 

 copper deficiencies in the pastures on which the pregnant ewes 

 have been grazed before lambing. A similar association has not 

 been recorded in man. 



Changes in lipid composition of the central white matter may 

 be illustrated by the following table compiled by Cumings from 

 cases of multiple sclerosis. 



Cerebral Lipids in Multiple Sclerosis 

 Lipids Normal white matter Demyelinated matter 



Total phospholipid 

 Sphingomyelin 

 Total cholesterol 

 Esterified cholesterol 

 Ganglioside 

 Water 



Results in grams per 100 g. fresh tissue except for ganglioside which is in grams per 

 100 g. dry tissue. 



Demyelinated white matter shows a marked decrease in total 

 phospholipid and total cholesterol with a very great increase in 

 esterified cholesterol. 



So far the cause and pathogenesis of multiple sclerosis and 

 other demyelinating diseases of man have eluded the investigator. 

 A little progress has come from animal studies which may in time 

 prove to be of some importance for the human problem. 



Both Swayback and the closely related condition enzootic 



