K. T. LEE, J. JARMOLYCH, D. N. KIM AND W. M. LEE 95 
Table IV. — Data Concerning Sivine Fed Mild Atherogenic Diet and X-irradiated Twice 
Pig 
No. 
PSC 
On diet 
before 
wks. 
Interval 
between 
wks. 
Survived 
after 1st 
wks. 
Weight, kg 
Scrum 
Cholesterol 
mg% 
Avg. lum- 
mm. 
Coronary Arteries 
Avg. wall 
(.11 ILK ilt^roo 
mm 
Virtual or 
totAl 
occlusion 
Infarct 
Init. 
Final 
Init. 
Final 
Rec* Old 
1 
X 
4 
4 
5 
10.6 
85 
132 
7 
4 
4 
5.4 
10.8 
90 
100 
a 
4 
4 
13.2 
16.6 
105 
165 
.85 
4 
4 
4 
4.8 
9.5 
100 
179 
.78 
5 
4 
4.5 
15 
20 
95 
181 
.93 
.18 
5 
7 
4 
4.5 
8.1 
14.1 
98 
158 
.80 
.13 
7 
4 
4.5 
10 
25.5 
110 
153 
.78 
.15 
8 
7.5 
4 
4.5 
9.1 
16.3 
108 
246 
.93 
.13 
9 
7.5 
4 
4.5 
13.6 
84 
149 
.85 
.18 
10 
7.5 
4 
4.5 
5.9 
10.6 
114 
213 
11 
7.5 
4 
5 
11.8 
14.7 
80 
135 
.78 
.15 
12 
7.5 
4 
9 
13 
19.7 
95 
227 
.50 
.25 
+ 
13 
7.5 
4 
10 
14.1 
21.1 
110 
315 
+ + 
14 
7.5 
4 
10 
17.3 
30 
85 
142 
.40 
.65 
+ 
* Recent infarct. 
Table V. — Data Concerning Swine Fed Stock Diet and X-irradiated Twice 
Pig On diet Interval Survived 
No. before between after 1st Weight, kg 
1st x-ray x-rays x-ray 
PS wks. wks. wks. Init. Final 
1 12 6 9 20.4 35.9 
2 12 6 10 17 34.5 
3 12 6 10 24.7 31.6 
4 12 6 18 11.6 30 
* Recent infarct. 
on diet before x-irradiation to give satisfactory- 
results. 
The hearts were examined systematically, 
both grossly and microscopically, for infarcts or 
other abnormalities. After fixation in 10% for- 
malin, the amount and severity of coronary ath- 
erosclerosis were measured by ocular mi- 
crometer.^ In brief, the procedure for the 
examination of the coronary arteries consists of 
a series of cross-sectional cuts along the course of 
the three main vessels. The cuts are made at 5 
mm intervals until an external diameter of less 
than 1 mm is reached. Alternate 5 mm segments 
of vessel are then removed (Figures 1 and 2), 
processed, and microscopic sections are pre- 
pared. Diameter of the artery, diameter of 
lumen, and wall thickness in its thickest and 
thinnest areas were measured. Average diame- 
ter of the lumen and average wall thickness 
were then calculated for all three main arteries. 
RESULTS— SERIES I 
The pertinent results of the experiment in Se- 
ries I are summarized in Tables II-V. Twenty- 
eight swine fed the severe (TSC) diet received 
Serum Coronary Arteries 
Cholesterol 
mg% Avg. lum- Avg. wall Virtual or Infarct 
inal diam. thickness total 
Init. Final mm mm occlusion Rec. Old 
95 152 1.28 .18 
56 154 1.03 .23 
84 162 1.18 .23 
94 98 1.05 .25 
x-irradiation twice. Starting approximately 4 
weeks after the last x-irradiation, 22 swine died 
rather suddenly without apparent signs of sick- 
ness. All had advanced coronary atherosclerosis 
and 24 swine had myocardial infarcts either 
healed or recent. In 17 out of 24 swine that had 
myocardial infarcts, there was evidence of 
congestive heart failure, characterized by 
marked congestion of the liver, pericardial, 
pleural or peritoneal eff'usion. 
Among the 14 swine fed the mild (PSC) diet 
exclusively, only 3 survived for 9 weeks or 
longer after the first x-irradiation and all 3 had 
myocardial infarcts. Main coronary arterial 
walls were markedly thickened in only one 
swine, but secondary coronary branches were 
markedly narrowed in all three. No gross visi- 
ble lesions were found in coronary arteries of 
four stock-fed swine even though they were 
x-irradiated twice. 
Histologic appearance of coronary lesions 
varied, depending upon the length of time the 
swine were on the diet and the length of the pe- 
riod after x-irradiation. The earliest change 
noted was smooth muscle cells (SMC) prolifer- 
ation, few cells thick, over normal appearing in- 
