300 



HORMONES 



counteract the excessive hormone production. This has been accom- 

 plished by partial or complete removal of the gland, or, more recently, 

 by the use of antithyroid drugs and chemicals. Many common foods 

 including spinach, cabbage, turnips, walnuts, lima beans, peas, carrots, 

 grapes, grapefruit, and others have distinct goitrogenic (goiter-producing) 

 or antithyroid effects. The responsible substance was obtained in pure 

 form from yellow turnips and was shown to be l-b-vinyl-2-thiooxazoli- 

 done. Various synthetic drugs such as 2-thiouracil and 6-propyl-2- 

 thiouracil also have marked antithyroid action. These substances do 

 not prevent absorption of iodine by the thyroid, but interfere with the 

 incorporation of it into the thyroid hormone. Some of them, e.g., propyl- 

 thiouracil, have proved to be very valuable in the treatment of Grave's 

 disease. 



H^a- NH 



I (4) (3) I 



^5-Viny 1- 2- thiooxazolidone 

 Nf===C-OH N===C-OH 



I (3) (4) I j (3) (4) I 



HS— C(2) (5)CH HS— C(2) (5)CH 



N^^L^CH N^-^^-^C-CH.CH.CH3 



2-Thiouracil 6-Propyl-2-thiouracil 



Radioactive iodine compounds containing the I^^^ isotope have also 

 found application in the diagnosis and treatment of excessive thyroid 

 activity. A small test dose of the radioactive iodine, for example, in 

 the form of potassium iodide, is given the patient, and the accumulation 

 of the iodine in the thyroid followed with a Geiger counter placed near 

 the throat. If an abnormally high fraction of the test dose enters the 

 gland, excessive thyroid activity is indicated. In this case, larger doses 

 of I^^^ are given, and as the iodine becomes lodged in the gland, the radia- 

 tions emitted by it kill a part of the thyroid tissue. Surrounding tissues 

 are essentially unaffected, and the extent of thyroid destruction can easily 

 be controlled by regulating the dosage. 



PROTEIN AND PEPTIDE HORMONES 



Hormones of the pancreas 



The pancreas is a pale pink organ about ten inches long in an adult 

 person, which produces a group of digestive enzymes and discharges them 

 into the small intestine. It also has the function of producing at least 

 one hormone, insulin, which is secreted directly into the blood stream. 



