608
ILSE L A S N I T Z K I
untreated controls with a corresponding rise of RNAP and LP. Cortisone also increased the growth-promoting effect of insulin: in cultures
treated with both hormones not only R N A P synthesis per cell, as seen
after insulin alone, but also LP synthesis was significantly increased.
Cornman (1951) demonstrated that deoxycorticosterone ( D O C )
damaged fibroblasts selectively. Usually, two different typer of cells
emigrate from explanted chick-embryo hearts: bipolar fibroblasts;
and polygonal endothelial elements which form a continuous sheet—
but, in general, the fibroblasts predominate. After treatment with
D O C (20 /xg/ml) both fibroblasts and endothelium shrank considerably
and showed a marked granulation of their cytoplasm; but whereas this
damage was irreversible in the fibroblasts the endothelial cells were able
to recover after removal of the drug. In cultures which had remained
viable after exposure to D O C the distribution of fibroblasts and endothelium had undergone a radical change and the majority of cultures
now contained mainly endothelial elements to the exclusion of fibroblasts. Administration of cortisone in concentrations of 50-150 ^g/ml
produced a similar result, but the effect was accelerated and increased
as compared with that of D O C . Cornman (1950) also studied the effect
of D O C and cortisone on the muscle of freshly explanted chick-embryo
heart. Such fragments normally continue to beat in culture for several
days after explantation. Addition of either D O C or cortisone to the
medium diminished or stopped the beat. This effect was reversible, and
the beat was resumed after removal of the drug.
Effect on Lymphocytes
It has long been known that exposure of animals to stress or shock
reduces the number of lymphocytes in the body. This effect is mediated
through the adrenal cortex since it fails to appear in adrenalectomized
animals, but can be reproduced by injection of adrenal cortical extract.
Schrek (1949, 1951) demonstrated that small doses of hydrocortisone
and cortisone significantly shortened the survival time of suspensions of
thymus lymphocytes in vitro but that deoxycorticosterone was inactive;
increasing the concentration did not increase the effect substantially.
Trowell (1953) confirmed and extended this work. He studied the
action of cortisone on organ cultures of lymph nodes from young rats
cultured in a serum-saline medium, and used the percentage of pycnotic lymphocytes as the criterion of damage. Normal 2-day cultures
of lymph nodes show usually 1—2% of pycnotic cells. Addition of
cortisone to the medium increased this percentage significantly but
did not affect the reticulum cells or macrophages. The number of
pycnotic cells rose with the concentration of cortisone and with the
length of exposure and increased proportionally to the log of time
ILSE L A S N I T Z K I
untreated controls with a corresponding rise of RNAP and LP. Cortisone also increased the growth-promoting effect of insulin: in cultures
treated with both hormones not only R N A P synthesis per cell, as seen
after insulin alone, but also LP synthesis was significantly increased.
Cornman (1951) demonstrated that deoxycorticosterone ( D O C )
damaged fibroblasts selectively. Usually, two different typer of cells
emigrate from explanted chick-embryo hearts: bipolar fibroblasts;
and polygonal endothelial elements which form a continuous sheet—
but, in general, the fibroblasts predominate. After treatment with
D O C (20 /xg/ml) both fibroblasts and endothelium shrank considerably
and showed a marked granulation of their cytoplasm; but whereas this
damage was irreversible in the fibroblasts the endothelial cells were able
to recover after removal of the drug. In cultures which had remained
viable after exposure to D O C the distribution of fibroblasts and endothelium had undergone a radical change and the majority of cultures
now contained mainly endothelial elements to the exclusion of fibroblasts. Administration of cortisone in concentrations of 50-150 ^g/ml
produced a similar result, but the effect was accelerated and increased
as compared with that of D O C . Cornman (1950) also studied the effect
of D O C and cortisone on the muscle of freshly explanted chick-embryo
heart. Such fragments normally continue to beat in culture for several
days after explantation. Addition of either D O C or cortisone to the
medium diminished or stopped the beat. This effect was reversible, and
the beat was resumed after removal of the drug.
Effect on Lymphocytes
It has long been known that exposure of animals to stress or shock
reduces the number of lymphocytes in the body. This effect is mediated
through the adrenal cortex since it fails to appear in adrenalectomized
animals, but can be reproduced by injection of adrenal cortical extract.
Schrek (1949, 1951) demonstrated that small doses of hydrocortisone
and cortisone significantly shortened the survival time of suspensions of
thymus lymphocytes in vitro but that deoxycorticosterone was inactive;
increasing the concentration did not increase the effect substantially.
Trowell (1953) confirmed and extended this work. He studied the
action of cortisone on organ cultures of lymph nodes from young rats
cultured in a serum-saline medium, and used the percentage of pycnotic lymphocytes as the criterion of damage. Normal 2-day cultures
of lymph nodes show usually 1—2% of pycnotic cells. Addition of
cortisone to the medium increased this percentage significantly but
did not affect the reticulum cells or macrophages. The number of
pycnotic cells rose with the concentration of cortisone and with the
length of exposure and increased proportionally to the log of time