MACROSCOPIC ALGAE (SEAWEEDS) 19 



Because alginates are not subject to breakdown by gastric juices, they 

 have been used successfully as a coating for medications designed to have 

 their effective activity in the intestine. Alginates have also seen much 

 application as hydroabsorbent agents in the management of constipation. 

 Berger and his colleagues 118 considered the water-absorbing and retaining 

 properties of sodium alginate superior to those of natural gums, methyl- 

 cellulose, and carboxymethylcellulose. They also found the acid-binding 

 properties of sodium and calcium alginate comparable to those of carboxy- 

 methylcellulose. Gill and Duncan 111 thought that alginates were less 

 effective in this respect than the carboxyl resins. Mulinos 119 tested the 

 sodium and calcium salts of alginic acid in 60 humans with colonic consti- 

 pation. He found them effective, and thought that, even though the algi- 

 nates swelled minimally in water or gastric juice, they increased their 

 original bulk 25 to 35 times in the alkalinity of intestinal secretions. 

 Ludwig and his associates 120 compared the alginates favorably with the 

 carboxylic type of cation exchange resins in their effect on intestinal 

 sodium and potassium. According to Feldman, 121 human subjects tolerated 

 45 gm. of alginic acid quite well. It acted as a mild laxative, and it in- 

 creased the fecal sodium and potassium to 16-20 per cent of that seen 

 with the common cation exchange resins. 



Since 1937, when Sears introduced the "reversible hydrocolloid 

 technic" in the preparation of dentures, the use of alginates in dentistry 

 has increased notably. 122 With this method, the dentist is able to secure 

 with one impression reproductions of multiple cavity preparations, to 

 reproduce undercuts without rupture or distortion, and to save chair time 

 for himself and the patient. 123 In a similar fashion, alginates are used for 

 fixed bridges 124 and dental hemostasis, 125 - 128 as well as for various types 

 of medical moulages. 129 



Alginates have also been put to the following medical uses: 



1. As an endaural wound dressing. 130 



2. As a mold for applying skin grafts after exenteration of the 



orbit. 131 



3. As a hemostatic in brain and thoracic surgery, 182 - 134 especially 



to close the bronchial tree in pulmonary tuberculosis, and 

 in extrapleural pneumothorax. 



4. As a decontaminant and treatment in mustard gas poisoning and 



burns. 135 



5. As swabs in the bacteriological examination of eating utensils, 



