Evening star., 1936-03-29

have found way to solve one Of the
fundamental problems of living nature
the chemical Transformation of food
into animal flesh.
This method already has shown that
the organic molecules, the bricks"
from which are built the cells which
are the fundamental units of the body,
continually are being destroyed and
resynthesized from fresh material.
The cells themselves, it long has
been known, are forever breaking
down and being rebuilt. Now, 1t ap-
pears, nature uses new bricks in the
building so that the body structure
continuously is being renewed and
strengthened with fresh material.
This fundamental advance was re-
ported to members of the American
Society of Bio-chemists, meeting here
today by Rudolph Schoenheimer and
D. Rittenberg of Columbia University.
About five years ago Prof. Harold
c. Urey of Columbia University and
DR.. H. G. Brickwedde Of the United
States Bureau of Standards isolated a
substance chemically identical with
the well-known gas hydrogen, but with
an atom double the weight of the
ordinary hydrogen atom. This heavy
hydrogen, it has since been found,
exists throughout nature in the pro-
portion of one part to every 5000
parts of ordinary hydrogen. If COM
bined with oxygen it forms heavy
water" chemically indistinguishable
from ordinary water and entering into
every chemical reaction in the same
way as ordinary water. But it weighs
more and has markedly different bio
logical effects.
Now water is a constituent of all
foods-carbohydrat fat or protein.
All of these foods can be made up in
the laboratory with ordinary water
molecules replaced with molecules of
heavy water.
Fats Essential in Diet.
Now, Drs. Schoenheimer and Rit-
tenberg pointed out in their report,
fats are essential in the diet. 1t has
been impossible to find out, however,
what happened to them because there
was no way to distinguish the fat
molecules taken in the form of food
from those already in the body.
Fat gathers under the skins of
animals, where it is kept in storage.
Whether this was the original fat
consumed by the animal, or whether
this was broken down and reformed
by the chemical processes of the. body
was not known. It also was known
that if animals we're fed no fat at
ply of proteins and carbohydrates,
fat would collect under the skin just
the same.
BY feeding to mice fats containing
heavy hyrogen, it was found that the
greater part of the ingested fat was
carried directly to these fat depots
and deposited there. A small part of
it was found to be burned irlmedi-
ately for the ordinary needs of the
animal, breaking down Immediately
and forming heavy water, which was
eliminated with the body fluids of
the animal.
Just as the chemist in the labora-
tory is able to make substances con-
tanning heavy hydrogen, so If an ami
NAL is given heavy water to drink, the
substances which are synthesized by
the body will contain the heavy hydro
gen atoms. 1t thus can be used to
label those substances which are man
ufactured in the body. If mice on a
fat-free diet are given heavy water to
drink. the bio-chemists reported, fat
containing heavy hydrogen can be re-
covered from the animals within a
short time after the beginning of the
experiment, despite the absence of fat
in their food. This proves that new
fats have been synthesized within the
animal body.
Quantity Not Increased.
Since the total quantity of fat in
the test animals did not increase dur
ing the experiment, it was concluded