PORPHYRIN IN HEMOLYTIC DISEASES 593 



There is one objection which may be raised against the methods apphed 

 in all these studies. If bacteria reduce oxyhemoglobin to hemoglobin, a small 

 part of the latter may be split by the acetic acid used in the isolation of the 

 porphyrin. This danger has been emphasized by Schumm {2^i)<>) as well as 

 by Fischer {SJtS), cf. also the study of the equilibrium between hemochrome 

 and porphyrins by Vestling (2872). 



The synthesis of porphyrins by microorganisms will be discussed 

 in Chapter XIII. In a number of instances porphyrins observed in 

 the human body or on the skin can be ascribed to such a synthesis. 

 In others a formation by the action of bacteria on hemoglobin appears 

 more likely. Figge and co-workers (7 51,753,14'^ 4) found several 

 porphyrins in the exudates of female genitalia. 



3.4. Is Pathological Porphyrin Formation Due to Deranged 

 Breakdown of Hemoglobin? 



3.4.1. Introduction. In Chapters X and XI it was shown that 

 the normal catabolism of hemoglobin leads to bile pigment without 

 free porphyrin appearing at any stage. This does not rule out the 

 possibility that, particularly under pathologic conditions, a small 

 fraction of hemoglobin may be catabolized in a series of reactions 

 which lead to porphyrin. 



Earlier workers (Garrod, Giinther) assumed that the porphyrin 

 formed in the human body in health as well as in disease arises by 

 breakdown of hemoglobin. This theory is still held by several workers, 

 particularly European workers (Schreus, 31^64^,2469; Carrie, 406, 

 1302; Vannotti, 2850; Vigliani, 2882; Paschkis, 2110). The investi- 

 gations of Dobriner, Rhoads, Watson, Rimington, and Turner have, 

 however, clearly demonstrated that the normal porphyrin formation 

 as well as that in most diseases occurs during hemoglobin synthesis, 

 not during hemoglobin breakdown. The evidence for this will be more 

 fully discussed in Chapter XIII. 



There is, however, reliable evidence {cf. Section 3.4.6.) that proto- 

 porphyrin can be formed by hemoglobin breakdown under certain 

 conditions, although the protoporphyrin found in the erythrocytes is 

 certainly not formed in this way. 



3.4.2. Porphyrin in Hemolytic Diseases. The theory of por- 

 phyrin formation by hemoglobin breakdown was based partly on the 

 finding of increased porphyrin formation in diseases in which an 

 increased breakdown of hemoglobin was known to occur, such as 



