Download ABSTRACTS OF PAPERS The somewhat triangular neural lobe

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ABSTRACTS OF PAPERS
The somewhat triangular neural lobe weighs
about 25 mg. and lies on the postero-dorsal
surface of the anterior lobe, connected to
the hypothalamus by a thin, attenuated
stalk. There is a well differentiated pars
tuberalis but a pars intermedia is lacking.
The blood pressure of the anesthetized
beaver increases following the injection of
posterior pituitary solution or vasopressin
but undergoes little or no change following
the injection of oxytocin.
The thyroid gland of the beaver is a paired
structure lying on either side of the trachea
and totalling approximately
2 gm. Preliminary histological studies reveal colloidfilled follicles and a uniformly low epithelium. The plasma protein-bound
iodine
content of blood obtained by cardiac puncture in a lightly anesthetized animal was 7
microgm. per 100 m!. The calcium, phosphorus and glucose values in the same specimen were 11.2, 5.8, and 69 mg./lOO ml.
respectively.
Homogenates of beaver thyroid concentrate radioactive iodine to a comparatively
high degree when dialyzed against a phosphate buffer solution containing radioactive
iodine. Salivary gland homogenates concentrate radioiodine almost as effectively as
thyroid homogenates. Homogenates of gut,
lymph node, liver, kidney, and spleen have
little concentrating ability. The ability of
thyroid homogenates to concentrate iodine
appears to be enhanced by Cu+r ion ..
A comparison of the effects of reserpine
and chlorpromazine to those of barbiturates
on central afferent systems in the cat. EVA
KING KILLAM AND KEITH F. KILLAM*.
Dept. of Anatomy, Univ. of Caliiornia, Los
Angeles. The effects of reserpine and chlorpromazine on responses in several afferent
systems known to be sensitive to very low
doses of barbiturates have been studied in
preparations
previously described (King,
E. E.: Fed. Proc., 13: 375,1954). At 1 mg.
per kg. chlorpromazine very slightly enhanced recruiting
responses,
especially
within the. thalamus, while having little
effect on EEG arousal responses measured
concurrently.
Following 2 to 8 mg./kg.,
amplitudes of all recruiting responses were
slightly depressed and thresholds slightly
increased. Thresholds for EEG arousal from
35
reticular formation or peripheral nerve
stimulation
measured in isocortex. were
raised only very slightly, and the duration
of the EEG low voltage, fast activity responses was reduced. Arousal within the
limbic system, which is indicated by slow,
high voltage waves, was more markedly depressed; the slow waves often being entirely
replaced by fast activity. EEG arousal in
isocortex following thalamic stimulation
was not altered by chlorpromazine and alloand juxt-allocortical
depression was less
marked. Reserpine, at 100 mg./kg. i.v., did
not alter recruiting or EEG arousal in stable
preparations
for periods up to 3 hours.
These results are in marked contrast to the
great enhancement of recruiting and blockade of EEG arousal obtained following 5 to
lO mg./kg. of barbiturates.
Thalamic recovery, as estimated from responses measured in medial lemniscus and capsule (King,
E. E., Naquet, R. and Magoun , H. W.: THIS
JOURXAL,113: 31, 1955), which has been
shown to be markedly depressed by barbiturates, was unaltered by chlorpromazine
and
reserpine.'
However,
spontaneous
seizures involving the limbic system have
been
observed
in animals
receiving
reserpine, and further studies of this system
are in progress. (Aided by a grant from The
Eli Lilly Company.)
The action of lysergic acid diethylamide
on central afferent and limbic pathways in
the cat. KEITH F. KILLA~f*ANDEVA KING
KILLA1\!.Dept. of Anatomy, Univ. of California,
Los Angeles. LSD-25 has been
studied on the following preparations evaluating afferent responsiveness: (1) cortical
and rhinencephalic "arousal" produced by
stimulation of the mesencephalic reticular
formation and the sciatic nerves, (2) cortical
and thalamic recruiting responses following
stimulation of mid-line thalamic nuclei and
(3) thalamic recovery cycles following sti·mulation of peripheral nerves. The recordings
were done in curarized cats under artificial
respiration.
Small
increases
in
the
thresholds of EEG arousal from sciatic and
reticular formation stimulation were noted
after 50 or 100 microgm./kg. i.v. Additional
administration
of the same doses either
produced no further effect or a return of the
thresholds to control levels. With the same
36
ABSTRACTS OF PAPERS
doses, recruiting responses were unchanged
except for slight reductions in the amplitude
of cortical responses. Preliminary studies
on thalamic recovery cycles also indicated
no change in pattern from control. In the
rhinencephalon, drug effects on the threshold
and duration of seizures produced by stimulation of the precommissural fornix were
investigated. Trains of stimuli at l50/sec.
for 3 seconds were applied at gradually increasing voltages until a seizure occurred.
Time intervals between series were not
less than 30 minutes. After 50 or 100
microgm./kg. i.v. of LSD-25 a progressive
increase in the duration of rhinencephalic
seizures was noted, but no change occurred
in threshold. In these animals only minimal
changes in arousal thresholds from either
sciatic or reticular formation stimulation
were observed. In this preparation, pentobarbital in doses of 5 to 20 mg./kg. raised
the seizure threshold progressively and
finally blocked convulsions completely.
(Aided by a grant from Eli Lilly Company.)
Experimental heart failure produced by
tetracycline antibiotics. GLENN F. KIPLINGER,* HE'<RY H. SWAIX*
AXD THEODORE
M. BRODY. Dept. of Phannacology, Univ.
of Michigan Medical School, Ann Arbor.
The tetracycline antibiotics (tetracycline,
chlortetracycline,
and
oxytetracycline)
were studied in the dog heart-lung preparation. It was found that heart failure induced
by the tetracyclines resembles failure induced by Versene (disodium EDTA) and
differs markedly from that induced by
pentobarbital in several ways. (1) With the
addition of each dose of a tetracycline or
Versene to the preparation, the right auricular pressure (RAP) rises sharply to a new
stable level within 30 to 60 seconds, while
after administration of a dose of pentobarbital the RAP rises gradually over a period of
10 to 15 minutes. (2) The tetracycline or
Versene-induced failure is readily and completely reversed by calcium ion, while the
pentobarbital
failure is not. (3) A heart
failed with a tetracycline or Versene will
recover spontaneously to a considerable
extent over a period of 30 minutes. A pentobarbital failed heart on the other hand does
not improve with time. Tetracyclines differ
from Versene in that lead acetate will
reverse Versene failure but will not reverse
tetracycline failure.
All observations are compatible with .the
explanation that the tetracycline antibiotics
and Versene produce heart failure by forming a chelate complex with calcium ion. Apparently lead salts can displace calcium
from the Versene complex but not from the
tetracycline complex. (Supported by a grant
from the Michigan Heart Association.)
Distribution and excretion of radioactivity following administration
of radioactive podophyllotoxin
to normal and
tumor-bearing mice. J. J. KOCSIS*, E. J.
WALASZEK* AND E. M. K. GElLING. Unio. of
Chicago. Radioactive podophyllotoxin was
biosynthesized by growing Podophyllum
peltatum (May Apple) plants in a C14O2enriched atmosphere. The labeled drug was
then isolated from the dried roots and
rhizomes by a modification of known procedures. The crystalline material so isolated
was identified as podophyllotoxin by its
melting point and ultraviolet absorption
spectra.
~[on-tumor-bearing
mice excreted 46%
of the injected radioactivity in the urine
and 43% in the feces following subcutaneous
administration
of sub-lethal doses (200
microgm.) of labeled podophyllotoxin. Of
the total radioactivity
excreted in the
urine, 47% appeared in the first 4 hours, an
additional 34% in the next 6 hours and by
24 hours, urinary excretion was essentially
complete.
Mice bearing Sarcoma 180 excreted considerably more radioactivity in the urine
(57%) during the first 4 hours following
subcutaneous administration
than either
normal mice (22%) or those with advanced
Ehrlich ascites tumors (16%). The gastrointestinal tract of normal mice, on the
other hand, contained higher levels of radioactivity (22%) 4 hours after administration
of labeled podophyllotoxin than the G.!.
tract of mice with Sarcoma 180 (9%) or
that of mice with Ehrlich ascites carcinoma
(3%). The disposition of radioactive podophyllotoxin would thus appear to differ
from that of radioactive colchicine (Cancer
Research, 13: 552, 1953) in normal and
tumor-bearing mice.
Conversion of the injected podophyllo-