» J « - Two years ago we completed studies on a total of 6 patients give these moderate therapeutic doses of 1311 for hypexthyroidism, buf un- fortunately, the full series of cultures was not always complete jon each patient. Some cultures failed and in two instances the large maber of initial control observations were not fully acceptable. From tha meager data on these patients, it appeared that there was ~ slight rise lin the incidence of chromosomal anomalies. Continuation cf the work waq Limited at that time because of shortage of personnel on our own staff ard on Dr. Macintyre's staff. During the past 1 years we have resumed thee studies with the participation of a graduate student who is addressing himself to | this problem. We have so far essembled information on 14 additic patients. The experimental design hae been as follows: for culture are obtained before any 131r was given. Samples bf blood Sufficient Hlood was obtained so that multiple cultures would be available to clearly establish an incidence of anomalies before the radiation wes given. Subsequently, samples of blood have been obteined for culture et 1, 4, 10, and 24 hours, and 2, 3, 7, and 14 days. Multiple cultures ere prepared from e of 1l to 18 samples of blood from each patient. The usuel Large battery of observations on the kinetics of the 1312 as deacribed in the firgt of this report were also being carried out. All series of part DRCESOMNE counts are done as comlete unknowns. At the time of reporting che year ago the data on 8 patients studied thoroughly suggested that pmo somal anomalies were being produced at a just significant level in patibnts given S to 8 millicuries of 131r, It was recognized that a consiHerably larger number of patients would be required to obtain enough data a clear answer to this issue. to get The new cases added to the study in the past year have not show a very significant rise in the number of chromosomal anomalies follbwing 131y except in one very ieant case. This particular case recei @ somewhat higher dose of I31I than did all of the others... Althong all of the kinetics are not fully analyzed, this pattent received] 19.2 Attention is now being directed toward patients who happen to be doses in this range. | There has arisen some concern that cells if incubated in their] Mc. seeiving own serum (which contained 1311) might sustain significant further rafiation effect during that incubation. [It could be argued that under the] former conditions some radiation might be sustained by the cells during ture rather than sustained solely before the cells were withdrawn from the patient. It seems that replacing the serum in the culture eliminktes any. radiation effect that might occur while the culture is being incubated. In the more recent studies, non-radioactive (pretreatment) serum has been obtained from the patient and stored and later used to replace th serum (in the cell cultures) that bears 131] when the blood is drawn. studies to compare the effects of 131 in the cultures have been By comparing the results with and without the radioactive serum if |Special fested. seems clear that the presence of the small emount of 13lr has no detecthble influence on the number of anomalies found. X-Ray Radiation Effect on the Thyroid As part of our studies on radiation effect on the thyroid we have had in progress a follow-up study of a selected group of patients who before 1950 received x-ray radiation to the neck and presumably to the thyroid area. Ail at ohnan fam Fook Aes et oa tad t= --- -®