Metabolism of fission products


Material Information

Metabolism of fission products progress report for month ending March 15, 1943
Series Title:
United States. Atomic Energy Commission. MDDC ;
Physical Description:
12 p. : ill. ; 27 cm.
Hamilton, Joseph G
Argonne National Laboratory
U.S. Atomic Energy Commission
Technical Information Division, Oak Ridge Directed Operations
Place of Publication:
Oak Ridge, Tenn
Publication Date:


Subjects / Keywords:
Fission products   ( lcsh )
Radioactive substances   ( lcsh )
Metabolism   ( lcsh )
Radioisotopes in the body   ( lcsh )
Radioisotopes -- Metabolism   ( lcsh )
federal government publication   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )


"Date Declassified: July 14, 1947"
Statement of Responsibility:
by Joseph G. Hamilton.
General Note:
Manhattan District Declassified Code
General Note:
"Date of Manuscript: March 15, 1943"

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University of Florida
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MDDC 1142


Progress Report for Month Ending March 15, 1943

Joseph G. Hamilton

Argonne National Laboratory

This document consists of 12 pages.
Date of Manuscript: March 15, 1943
Date Declassified: July 14, 1947

.ri S TOR -7 i

This document is for official use
Its issuance does not constitute authority
for declassification of classified copies
of the same or similar content andtitle
and by the same author (s).

Technical Information Division, Oak Ridge Directed Operation
Oak Ridge, Tennessee







RADIOLANTHANUM (La') (Complete Report) 1
1) Preparation Without Carrier, Roy Overstreet and Louis Jacobson 1
2) Tracer Studies, Kenneth Scott and Harvey Fisher 1

RADIOCERIUM (Ce'4) (Progress Report) 1
1) Preparation Without Carrier, Roy Overstreet and Louis Jacobson 1
2) Tracer Studies, Kenneth Scott and Harvey Fisher 2

Preparation of a New Sample Without Carrier, Roy Overstreet
and Louis Jacobson 2

RADIOSTRONTIUM (Sr") (Progress Report) 2
Tracer Studies, I. L. Chaikoff, M. C. Fishier, and C. Entenman 2

FROM THE BODY. (Progress Report), D. M. Greenberg and Nathan Kaplan 2

RADIOLANTHANUM (La'4) (Complete Report) 2
1) Preparation Without Carrier 2

2) Tracer Studies 3
Method of Study 3
Results 5
Discussion 7

Experimental 9
Results 9




By Joseph G. Hamilton



1) Preparation of Radiolanthanum Without Carrier
A satisfactory method for the preparation of La"4 has been successfully developed. The
twelve-day Ba"4 has been separated from fission products with the use of inert Ba as a carrier.
Following the preparation and purification of the Ba'0, the radiolanthanum was separated from the
former using ferric hydroxide as carrier. The iron was subsequently removed by extraction with
isopropyl ether. Decay curves have been measured on La"0 samples thus separated and the half-
life found to be 40.9 hours. No detectable long-lived tail was observed in samples followed over as
long an interval as seven half-lives. This indicates that there was present less than 1% of any
long-life impurities such as radiobarium or radioactive rare earths. The half-value thickness for
the beta rays using Al absorbers was found to be 86 milligrams per square centimeter.

2) Tracer Studies
The distribution of La'40 following intraperitoneal and intramuscular injection was followed for a
period of eight days. A significant proportion of the injected material remained unabsorbed by both
routes of administration. The liver and skeleton were found to show the highest accumulation of
this element. The uptake per gram of tissue in the liver was considerably higher than in the case
of Y". The uptake by the bone per gram of weight was significantly less in the case of La'4 How-
ever, the La2' was accumulated in the bone and was firmly fixed in this organ. No significant
absorption took place by way of the digestive tract. When Lao40 was introduced directly into the
lungs, it was found that a large proportion was firmly fixed in this structure.


1) Preparation Without Carrier
Radiocerium has been prepared from a uranium fission mixture without the use of Ce carrier.
Thorium was used as a carrier, and the thorium and cerium finally separated from one another by
iodate precipitation. The identity of the purified radiocerium without carrier was demonstrated by
the following procedure:
a) Chemical identification with the use of inert Ce as a carrier upon an aliquot fraction of the
final purified solution.
b) Confirmation of the presence of short-lived praseodymium daughter which was described by
Spedding in report CC-418.
c) Beta-ray absorption curves were found to be comparable to those published in various re-
ports of the chemistry group.

MDDC 1142 I 1

MDDC 1142

2) Tracer Studies *
A large group of animals have been injected with Ce>t0 by intraperitoneal and intramuscular
injection without carrier. A sufficient number have been injected so that they may be sacrificed in
groups of 3 extending from the 1-day period to the 64-day period. In addition, some animals have
received Ce>'0 by stomach tube. Preliminary results, which include the 1-, 4-, 8-, and 16-day
period, reveal that Ce >40 is handled in a manner very similar to that observed with La140. No
significant absorption occurs by way of the digestive tract. Considerable retention by the lungs was
noted when the radiocerium was administered directly into this organ. A full report will follow.


Preparation of a New Sample Without Carrier
Eighteen pounds of uranyl nitrate have received 10,000 microampere hours of beryllium neu-
trons. The bombarded material was then extracted repeatedly with ether to remove the uranyl
nitrate, and the fission products were separated without the addition of carrier. This separated
mixture now contains less than 5 milligrams of uranium in a total of 8 millicures of activity. An
assay of the different fission products is now being completed and the material should be ready for
use April 1 for tracer studies.


Tracer Studies
A continuation of this work with more complete data indicates that the retention of Srm by the
skeleton was essentially as has been described in a previous report, CH498. The uptake of this ma-
terial in the bones of the animals, which received it by mouth, was found to rise by almost a factor
of 2 between the 4th and 16th days. Otherwise, there were no significant differences to be observed
between the present more complete information and that which was given previously. The rate of
excretion of SrB has now been followed for a period of 30 days, and after the 15th day its rate of
excretion is apparently less than the rate of decay of that which is retained in the body. A complete
report on the Sr studies up to 64 days will be presented in the next six weeks as a complete report.


Preliminary experiments on removal of Sr' from rats have indicated that sodium citrate,
parathyroid hormone, ammonium chloride, and strontium chloride apparently slightly enhance the
removal of Sr"s. Massive doses of irradiated ergosterol have no such effect. This study must be
repeated upon a much larger group of animals at varying periods after Srt administration before
any quantitative apprisals as to the relative effect of these different agents may be made.



Uranium metal on an iron target was subjected to a deuteron bombardment of 10,070 micro-
ampere hours at 16 Mev. The period of bombardment was from December 8 to December 29, 1942.

MDDC 1142

On January 23, 1943, all exposed parts of the target, except the uranium, were covered with
paraffin, and the uranium was treated repeatedly with concentrated HNO. Over 90% of the activity
was thus removed from the target. A large excess of concentrated HCI was added and the solution
evaporated to a small volume. Iron was removed by extraction with isopropyl ether and the aqueous
phase evaporated to a value of 10 cc.
Fifty mg of Ba were added, and the mixture was saturated with HCl gas and the resulting BaCIl
precipitate removed by centrifugation. Twenty-five mg more of Ba were added to the supernatant
liquid and BaCL, again separated out. The Ba precipitates were combined, dissolved in a little water,
and reprecipitated 4 times with HCI.
The final BaCl2 precipitate was dissolved in water. Ten mg of FeCI, were added. The solution
was made alkaline with NIOH and heated to boiling. The Fe(OH), precipitate was removed by cen-
trifugation and discarded. This process was repeated once more and the final BaCl2 solution acidi-
The purified BaCL, solution was set aside for 7 days to allow for the growth of the lanthanum
daughter. Lanthanum was then separated out as follows: Ten mg of FeCI, were added and the liquid
diluted to about 40 cc. The solution, made basic with NHIOH, was heated to boiling and the Fe(OH)I
separated out. After acidifying, the supernatant liquid was set aside for future "milkings". The
Fe(04 precipitate (containing the La) was dissolved in 40 cc of 0.5N HCI and reprecipitated twice
with NHBOH, adding 50 mg Ba as hold-back carrier each time. Following this, the iron was reprecip-
itated twice without the addition of barium hold-back carrier and finally washed with 40 cc water.
The washed precipitate was dissolved in a small volume of 9N HCI, the iron extracted with iso-
propyl ether, and the aqueous phase evaporated just to dryness. The residue was taken up in a few
drops of concentrated HC1, and diluted with water. Finally, the solution was made isotomic in NaC1,
the pH adjusted to 2.7, and the volume made up to 11.0 cc. Suitable aliquots were taken for absorp-
tion and decay curves.
For the Al absorption curve, the sample was mounted on cellophane. The decay curve, extending
through seven half-lives, showed no evidence of contamination. The half-life, as determined on this
sample, was 40.9 hours (see Figure 1). The half-value thickness for the beta rays, as measured on a
Lauritsen Electroscope, was found to be 86 mg Al cm-e. This value is similar to the one reported
by Goldschmidt and Perlman, CC295.


Method of Study
Three groups of rats, each group comprising 3 animals, received approximately 5 microcuries
of the purified radiolanthanum as a LaCls solution at pH 2.7 by intraperitoneal injection. Three
similar groups of animals received this material by intramuscular injection. The intraperitoneal
and intramuscular groups were sacrificed at the following intervals after injection: I day, 4 days,
8 days. The excreta were collected from all of the animals as was done in the radioyttrium studies.
The tissues were secured from the animals at the time of sacrifice and ashed at 500 degrees centi-
grade in porcelain dishes. The ash from each sample was weighed and transferred to a small
porcelain dish 4 centimeters in diameter. One cc of water was added and the mixture subsequently
evaporated in a hot air oven in order to evenly distribute material in the dish. In this manner it was
possible to determine with reasonable accuracy the number of milligrams per square centimeter of
the ash present. Self-absorption curves, using sodium chloride, were made on a.iquot samples of the
La'" so that proper correction for the self-absorption in each sample could be made. The weaker
samples were measured by a counter tube which had a mica window of 11 milligrams per square cen-
timeter. The stronger samples were measured with a Lauritsen Electroscope. The distribution of
the radiolanthanum in the tissues of the animals which had received this material by intraperitoneal
and intramuscular injection is given in Tables 1, 2, and 3. The excretion data appears in Table 4.

MDDC 1142






, 0.6





30 60 90 120

210 240 270 300


Each of another group of 3 animals received approximately 5 microcuries of La140 solution by
stomach tube. Four days later they were sacrificed and their tissues assayed in the manner noted.
An additional group of 5 animals were given a solution containing La"14 directly into the lungs. The
exact quantity entering the lungs could not be determined since a considerable proportion of the so-
lution thus administered was coughed up and swallowed. Two of the animals were sacrificed at 2
days, and the remaining 3 at the end of 4 days. The excreta were not collected from these 5 animals.
The data concerning the pulmonary experiment are noted in Table 5.

\ 140
Figure k Decay curve for La140

-- ---------- -
==== === \

0.02 L

MDDC 1142

Table 1. Distribution of La140 one day following intraperitoneal and intramuscular

One-day I.P. One-day I.M.
injection injection

(% per (% per (% per (% per
organ) gram) organ) gram)

Heart .05 .057 .06 .070
Liver 51.44 5.39 23.00 2.18
Kidney 1.48 .75 .60 .323
Spleen .76 .77 .06 .096
Muscle' 1.16 .011 .66 .006
Skin' 2.72 .065 .74 .020
Stomach .60 .315 .05 .013
Sm. intestine 2.02 .319 .10 .016
Lg. intestine .22 .247 .02 .025
Bone' 16.47 .821 8.53 .300
Lungs .15 .094 .07 .037
Brain .007 .003 .009 .006
Blood' .60 .030 .68 .033
Lymph glands .061 .038
Adrenals .05 .493 .064
Mesenteric fat .107 .006
Tail fat .050 .028
Ovaries .003 .023
Testes .43 .087
Feces .282 .012
Total urinary excretion 1.19 .039
Total fecal excretion 6.70 .530
Balance (carcass') 12.74 66.00
Total recovery 94.50 99.32

'Muscle was calculated on basis of 45%, of total body weight.
2Skin was calculated on basis of 42 grams.
'Measured value for entire skeleton.
4Blood was calculated on basis of total body weight.
SMeasured value of entire carcass less tissue samples and skeleton.
This value, less values for muscle and skin, probably is largely made up
up of unaDsorbed La40.
It is apparent that a very large proportion of the uptake of La140 by both intraperitoneal and
intramuscular administration occurs in the liver and skeleton. It will also be noted that a con-
siderable proportion of the administered material was present in the carcass. It appears in all
likelihood that this is due to lanthanum which escaped absorption. It will also be seen that the car-
cass values were consistently higher in the intramuscular groups than in those that received lan-
thanum by intraperitoneal injection. It is also noteworthy that the content of the La'40 in the abdom-
inal organs is significantly higher in the animals which received this material by intraperitoneal
injection. This difference must be due, at least in part, to the fact that part of the solution re-
mained unabsorbed on the surfaces of the intra-abdominal structures. The highest concentrations
on a per gram basis are in the liver and bone.

MDDC 1142

The uptake of La'40 in the animals which received this material by stomach tube and were sac-
rificed 4 days later, revealed that approximately .3% was actually absorbed by the body. The small
amount which was taken up was found to be in the liver. All of the other tissues and the carcass con-
tained less than .005% per gram of the administered dose. This indicates that the absorption of lan-
thanum from the digestive tract is insignificant.
The findings noted from the two groups of animals which received the La solution directly
into the lungs, indicated that this substance is apparently very tenaciously held by the pulmonary
tissue. (See Table 5). The distribution of the La140 in the rest of the tissue is essentially similar
to the results noted in the intraperitoneal and intramuscular groups. Unfortunately it is not possible

Table 2. Distribution of La140 at four days following intraperitoneal and intramuscular

Four-day 1.P. Four-day 1.M.
injection injection

(% per (% per (% per (% per
organ) gram) organ) gram)

Heart .03 .038 .03 .035
Liver 39.07 3.34 28.07 2.50
Kidney .79 .330 .928 .459
Spleen .39 .342 .072 .062
Muscle' 2.34 .019 1.28 .011
Skin2 1.38 .031 2.16 .051
Stomach 1.24 .359 .11 .032
Sm. intestine .92 .070 .46 .047
Lg. intestine .06 .087 .017 .031
Bone3 19.08 .804 24.56 .853
Lungs .07 .043 .08 .049
Brain .002 .002 .003 .003
Blond4 .042 .002 .067 .003
Lymph glands .058
Adrenals .325 .003 .043
Mesenteric fat .034 .008
Tail fat 0.13 .013
Testes .50 .103 .05 .007
Feces .535 .290
Total urinary excretion .407 .278
Total fecal excretion 7.63 5.20
Balance (carcass) 18.67 26.77
Total recovery 88.91 87.89

Muscle was calculated on basis of 45% of total body weight.
2 Skin was calculated on basis of 42 grams.
3 Measured value for entire skeleton.
4 Blood was calculated on basis of total body weight.
5 Measured value of entire carcass less tissue samples and skeleton. This value,
less values for muscle and skin, probably is largely made up of unabsorbed La' .



Table 3. Distribution of La40 at eight days following intraperitoneal and intramuscular

Eight-day I.P. Eight-day I.M.
injection injection
(% per (% per (%per (% per
organ) gram) organ) gram)

Heart .03 .027 .07 .09
Liver 29.77 3.16 19.20 1.87
Kidney .473 .245 .86 .400
Spleen .364 .696 .091 .111
Muscle' 1.09 .010 1.94 .017
Skin2 5.44 .127 3.43 .083
Stomach .49 .136 .10 .039
Sm. intestine .88 .098 .367 .036
Lg. intestine .13 .152 .04 .020
Bone' 15.74 .634 25.26 1.127
Lungs .33 .199 .088 .036
Brain .023 .021 .031 .018
Blood' .177 .009
Lymph glands .1i .14
Adrenals .031 .23 .014 .21
Mesenteric fat .072
Tail fat .054
Ovaries .021 .290
Testes .067 .020
Feces .026 .284
Total urinary excretion 6.00 1.73
Total fecal excretion 26.14 17.62
Balance (carcass) 13.30 25.26
Total recovery 93.13 104.07

Muscle was calculated on basis of 45% of total body weight.
2Skin was calculated on basis of 42 grams.
Measured value for entire skeleton.
Blood was calculated on basis of total body weight.
SMeasured value of entire carcass less tissue samples and skeleton This value,
less values for muscle and skin, probably is largely made up of unabsorbed La40 .

to determine the actual amount of La140 injected into the lungs since the largest portion of the so-
lution is promptly coughed out after administration. The values given in Table 5 were secured by
removing the digestive tract, then assaying the other tissues in the usual manner. The figures given
simply represent the distribution of the measurable activities in the different organs. It will be re-
called from an earlier report, CH948, that radioyttrium when introduced into the lungs behaved in a
similar manner.


It is of interest to note that the distribution of La140 following intraperitoneal injection is similar
to the results encountered in radioyttrium. It appears that the lanthanum, when fixed in the bones,
was held there quite firmly although the total uptake was less than was found with Y"'. The absence

MDDC 1142

MDDC 1142

Table 4.

Intraperltoneal Intramuscular
injection injection
No. at
Days determinations Urine Feces Urine Feces

1 3 1.06 3.93 .36 .42
2 2 .10 .88 .14 .78
3 2 .16 2.95 .053 2.11
4 2 .16 2.95 .13 2.23
5 1 .19 .67 .077 1.91
6 1 .05 3.37 .077 1.91
7 1 .04 4.60 .087 4.51
8 1 .07 5.45 .099 3.54

Total 1.83 24.80 1.023 17.41

Table 5. Distribution of La'"4 following intrapulmonary administration of a solution
of LaC,.

Two days (2 animals) Four days (3 animals)
(% uptake (% uptake (% uptake (% uptake
Tissues per gram) per organ) per gram) per organ)

Liver .7 9.1 1.0 12.3
Kidneys .4 1.2
Spleen .2 .2
Bone 1.5 27.5 .3 10.7
Lungs 25.5 36.7 32.8 64.9
Balance ~.1 26.7 .05 9.,

All other tissues had insufficient La'40 to be measured,with the exception of the
digestive tract in the two-day group where the content of unabsorbed La'40 was .6%
per gram. The content of La140 in the other tissues was less than .1% per gram.
The distribution given expresses the relative content of measurable La'" in the tis-
sues indicated.

of any significant absorption of La'"4 from the digestive tract is quite similar to the findings noted
in Ye". The retention of La"14 in the lungs appears, if anything, to be greater than was noted for Y".
The excretory pattern for La'40 is likewise similar to that observed with Yo, except that the fecal
excretion of the former appears to be maintained at a higher rate with the passage of time. Marked
irregularities in the rates of excretion were noted in the different groups receiving La14 by intra-
peritoneal and intramuscular injection.
The general picture of La'40 is in many respects, therefore, quite similar to observations noted
with Y".

MDDC 1142 9


The first experimental series reported here represents a preliminary experiment. The results
obtained are chiefly of value as a guide for the conduct of future experiments and are in themselves
inconclusive. In this report there will first be discussed the method of conducting and the results of
the present test. This will be followed by an outline of the plan for future experiments.


The animals tested were of the same weight and age. After the 21-day preliminary period fol-
lowing administration of Sr" they were placed in individual metabolism cages each fitted with a de-
vice for separating urine and feces. Collections of feces and urine were made daily. The excreta
were ashed and the counting was carried out on the whole or aliquots of the ash. At the end of the
experimental period, the animals were sacrificed. One femur was removed from each animal to de-
termine the Sr" content of the bones, and the rest of the carcass was ashed to determine the residual
Sra remaining in the body of each animal.
The material to be counted was introduced into metal ointment tins and the radiations were
counted with a bell-shaped mica window counter tube. Corrections for self-absorption were applied
from standard curves run for this purpose.
The animals were placed on a fairly low calcium diet and given the treatment shown in the head-
ing5 of Tables 6 and 7. The NHCI, SrCls, and sodium citrate solutions were put into the drinking
water bottles. About 10 cc of each of the fluids were consumed per rat per day. Equivalent doses in
an adult man would represent 1.5 million units of vitamin D, 12,000 units of parathyroid hormone,
3 g NHCI, 30 g SrCL, and 4.8 g of sodium citrate, respectively, per day.


With the exception of the animal given parathyroid extract injections, all the animals survived and
appeared in good condition at the end of the experiment.
The following tentative conclusions have been drawn from this first experimental series.
1) Because of the biological variations among animals, a fairly large series of experiments will
have to be carried out to obtain results that are statistically significant.
2) The data shown lead to the tentative conclusion that administration of ammonium chloride,
strontium chloride, sodium chloride, sodium citrate, and parathyroid extract lead to an Increase in the
rate of excretion of radiostrontium from the body. Irradiated ergosterol does not. The increase in ex-
cretion is not large. These results are similar to the findings recorded in the literature on the effects
of the treatment of radium poisoning with irradiated ergosterol, ammonium chloride, and parathyroid
3) With the exception of sodium citrate, all the effective treatments caused increase in the Srm
contents of both urine and feces. Sodium citrate, it is noteworthy, caused some decrease in the ex-
cretion by way of the urine, and an increase in fecal excretion. This may be a point of some signifi-
cance in minimizing the contact of the kidneys with the toxic radiations.

MDDC 1142

Table 6. Elimination of radiostrontium in urine and feces by various regimes expressed as per cent
of administered dose.

Therapeutic regimes
5000 units

Control daily 1.0% NH4C
r--^--* r--- ---- A '---*------ A
Feces Urine Feces Urine Feces Urine

Excretion prior to start of experiment
Total (21days) 44.5 42.8 39.7

Excretion prior to start of experimental regimes

1 0.093 0.036 0.131 0.018 0.041 0.045
2 0.074 0.062 0.124 0.021 0.068 0.029

Excretion during experimental regimes

1 0.082 0.021 0.158 0.062 0.190 0.046
2 0.063 0.030 0.112 0.078 0.162 0.028
3 0.173 0.017 0.088 0.050 0.166 0.045
4 0.158 0.034 0.120 0.054 0.184 0.048
5 0.139 0.030 0.077 0.019 0.186 0.038
6 0.10' 0.019 0.065 0.040 0.170 0.027"
7 0.106 0.021 0.070 0.060 0.178 0.070
8 0.098 0.027 0.078 0.046 0.136 0.043
9 0.102 0.033 0.077 0.045 0.178 0.032
10 0.077 0.038 0.044 0.041 0.181 0.025
11 0.107 0.013 0.108 0.038 0.204* 0.022
12 0.110 0.023 0.049 0.033 0.175 0.017
13 0.111 0.016 0.118 0.031 0.164 0.010
14 0.095 0.020 0.107 0.023 0.191 0.018
Total 1.521 0.342 1.271 0.620 2.465 0.469

Sum of feces
and urine 1.86 1.89 2.93

Carcass 45.9 46.4 51.0
Bone (femur) 1.6 1.4 2.4
(per gram) 93.7 86.5 86.0

MDDC 1142

Table 7. Elimination of radiostrontium in urine and feces by various regimes expressed as per cent
of administered dose.

Therapeutic regimes
r 0.2 cc para-
1.6% thyroid extract
1.0% SrCl2 Sodium citrate twice daily
Feces Urind Feces Urine Feces Urine

Excretion before start of experiment

Total (21 days) 40.6 36.3 29.0

Excretion prior to start of experimental regimes

1 0.034 0.016 0.082 0.048 0.150 0.031
2 0.039 0.025 0.076 0.053 0.116 0.056

Excretion during experimental regimes

1 0.216 0.067 0.197 0.010 0.150 0.031
2 0.234 0.100 0.316 0.003 0.153 0.072
3 0.191 0.063 0.214 0.010 0.140 0.080
4 0.172 0.069 0.179 0.015 0.190 0.037
5 0.163 0.081 0.241 0.026 0.148 0.052
6 0.168 0.071 0.185 0.021 0.146 0.033
7 0.150 0.075 0.214 0.016 0.141 0.048
8 0.190 0.053 0.180 0.014 0.211 0.067
9 0.183 0.069 0.201 0.029 0.173 0.052
10 0.154 0.040 0.236 0.019 Animal
11 0.145 0.061 0.238 0.012 Died
12 0.216 0.058 0.180 0.014
13 0.233 0.045 0.195 0.012
14 0.121 0.025 0.183 0.021

Total 2.530 0.877 2.959 0.221 1.458 0.442
Sum of feces
and urine 3.41 3.18

Carcass 52.2 56.6 67.4
Bone (femur) 2.2 2.5 2.9

(per gram) 98.4 98.6 91.2

12 1 MDDC 1148 *


1) The variability among the experimental animals makes it imperative to run groups of animals
for each of the different treatments. The collecting of daily samples involves too much work to allow
this. Consequently, It is proposed to carry out the new experiments on weekly samples. Collections
will be made at daily intervals, but these will be pooled for the analyses. By this measure it will
probably be possible to carry 4 or 5 times as many animals.
2) The current conception of bone metabolism is that material in the trabeculae is removed fairly
readily; material in the shaft is difficult to eliminate. The elements that get into the bone first are
taken up by the trabeculae and, with the passage of time, are transferred to the shaft. Measures taken
early after contamination are apt to be more successful than late measures. The rate of life activity
of the rat is about 20-fold as rapid as that of man. This includes life span, growth, etc. Because of
this, experiments will have to be undertaken to test the effects of the experimental regimes at dif-
ferent time intervals after the introduction of the radioactive material. As a start, there will be taken
the period of 1 week. This is equivalent to about 4 or 5 months in man.
3) The elements that accumulate in bone follow the stream of calcium and phosphorus metabolism.
We propose to make more use of this by determining the calcium and phosphorus exchange, as well as
the Sr exchange, in the experiments to be carried out in the future.


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