- 1 9 5 - 



12.9^ of the concentrate. Per the rabbit the MPD was 0.3 gammas 

 per kilogram of body weights The LD50 ^'^ ^^^ mouse was 75^000 

 gammas per kilogram of body weight, 



666. NEVA, P. A. and MORGAN, H. R. 



Tolerance to the action of endotoxins of enteric bacilli in 

 patients convalescent from typhoid and paratyphoid fevers 



J. Lab, Clin. Med, 35:911-922, 1950 



Initial dosages of 5.0 micrograms of typhoid antigen ( or alter- 

 nate doses of S. dysenteriae antigen and typhoid antigen) were 

 administered to convalescents recovering from typhoid or para- 

 typhoid A fevers. The antigens had been prepared by the method 

 of Morgan. When compared with healthy subjects who received the 

 same amounts of the two antigens, a definite tolerance or resistance 

 to the pyrogenic activity of toxic somatic antigen was demon- 

 strated after convalescence; this was unrelated to the amount of 

 circulating antibody. No tolerance was exhibited toward the 

 toxins following recovery from other infections (bacillary dysenr 

 tery, gonococcal arthritis, pneumococcal pneumonia and tularemia). 

 Other investigators have advanced the theory that increased 

 activity in the reticuloendothelial system may underlie the 

 mechanism by which tolerance develops. 



667. New light on endotoxins 



Editorial Note. The Lancet 1:722, I95O 



The somatic antigen or endotoxin which may be extracted from 

 members of the colon-typhoid-dysentery group (possibly excepting 

 S^. shlgoe) is attributable to a polysaccharide and nitrogen 

 complex. It produces circulating antibodies, a terminal 

 circulatory hypertension n hyperthermia^ transient hyperglycaemla 

 and succeeding hypoglycaemia. Its hemorrhagic action on the 

 placenta is followed by abortion; similar activity occurs in 

 transplanted tumors. Adrenal cortical extract appears to prevent 

 certain toxic effects, which are more lethal for the guinea 

 pig than for mice; the ratio was 17.5 to 1 when guinea pigs were 

 injected subcutaneously with a suspension of heat-killed B. coll 

 organisms. Mice received intravenous doses. The gross appear- 

 ance of lesions suggests that capillary hemorrhages are pro- 

 duced by a terminal hypertensive action. Antibodies in serum 

 from a mouse immunized with endotoxin were 30 times more potent 

 than commercial B. coli antiserum in protecting others of the 

 species against B. coll infection. 



I 



