244
ABSTRACTS
The dose recommended is 2 gm. of an oily emulsion, intra-
muscularly, at an interval of a week. More than two courses
are rarely necessary. As many as 8 gm. have been given
to patients without toxicity. The emulsion is prepared
by triturating the finely-powdered drug in a sterile mortar
with 0.35 gm. of adeps lanæ and about 15 c.c. of olive oil,
previously sterilized by heating at 150°C. for one hour. Five
c.c. of sterile water is then added and the emulsion is produced.
A further 20 c.c. of olive oil is then added and the emulsion
is poured into previously sterilized two-ounce medicine
bottles and sealed. Sterilization should be completed by
heating the bottles in an autoclave at 115°C. for 30 minutes.
One injection of 2 c.c. of 3 per cent 'novutox' should
be given on the upper part of the worm sinus and two similar
injections below it. This should be followed by an injection
of 20 c.c. of the phenothiazine emulsion in the upper part
of the worm sinus and two injections of 10 c.c. each below
it, along the tract of the previous injections of 'novutox.'
The emulsion of phenothiazine should not be allowed to cool
down much, otherwise the drug will precipitate. The most
important part of the whole treatment is to see that half
of the emulsion is injected as near the course of the buried
worm as possible. Both local and general concentration of
the drug is very important. [G.D.B.]
Cryptococcus infection in equidae. S. C. J.
BENNETT (1944). J. roy. Army. Vety. Corps 16,
108-18
ATTEMPTS have been made by a few workers to create new
species classification of Cryptococcus ; the author is, however,
of the opinion that there is no justification for this, until
more substantial evidence for the creation of new species
is forthcoming; and that, until this question is decided,
all cryptococci causing suppurative infections in equidæ
should be regarded as that of C. farciminosus only.
C. farciminosus should be regarded as a pyogenic orga
nism liable to be found in any suppurative lesion in any
part of the body. Microscopic examination of pus smears
is the only sure means of diagnosing the disease and the
author advocates more general use of the microscope in
diagnosis, even though the lesion in no way resembles the
textbook description of the disease.
In the absence of
such examination, the real nature of the infection is likely
to be missed and such cases act as dangerous carriers of the
disease. The discharge from recently dressed open wounds
may not show the specific organisms.
Experimental evidence shows that the incubation period
in this disease is shorter than has hitherto been stated :
undiagnosed and atypical cases, such as cryptococcal con-
junctivitis, represent the ' missing link ', and the writer
describes a few cases in his experience in support of this
view.
A suggestion is made that the policy of slaughtering in-
fected animals in enzootic areas should be abandoned and
treatment undertaken. A few hints are offered regarding
the selection of promising cases for surgical treatment and
the importance of hospital hygiene in the control of this
disease. [P.R.K.]
The utilization of urea in the bovine rumen.
1, 2, 3. R. M. PEARSON, AND J. A. B. SMITH
(1943). Biochem. J. 37, 142-64
THE work was undertaken to test the contemporary theory
that when urea is fed to ruminants with a suitable diet it is
converted to protein in the rumen and is thus digested by
the animal.
The first article is concerned with the details of the methods
adopted for estimating non-protein nitrogen, urea and ammo-
nia, with the heterogeneity of the rumen ingesta of a steer
and with some preliminary in vivo experiments. Compara-
tive study of trichloracetic acid, sodium tungstate with
sulphuric acid and alcohol as protein precipitants showed
that the alcohol and sodium tungstate methods give similar
results, whereas trichloracetic acid gives much higher values.
Details of the sodium tungstate method finally adopted are
also given. Heterogeneity of the rumen ingesta is described
and illustrated by analyses. Determinations of nitrogen
distribution values on samples taken at the same time from
different positions in the rumen showed a variation between
extremes of almost 20 per cent. Sampling difficulties are
also described. Determinations of protein and non-protein
nitrogen in the rumen ingesta after meals with and without
urea showed no significant difference between protein values
in the two cases, though there was a change in the non-
protein nitrogen fraction. The average results gave no
satisfactory evidence for the synthesis of protein from urea,
The in vivo programme was abandoned owing to its inherent
difficulties. Similar in vivo experiments by Wegner, Booth,
Bohsted and Hart are described and discussed.
The second article deals with in vitro experiments. Pre-
liminary incubation experiments showed that rumen con-
tents were able to convert urea to ammonia. So it was
thought probable that utilization of urea by ruminants
involved the conversion of urea to ammonia at the first
stage of the process. A detailed study of this conversion
was made. Methods of obtaining the sample of rumen
contents and incubation of the rumen liquor are described.
Results showed that the rate of conversion of urea to ammonia
was much the same with carbon dioxide, nitrogen, and air.
Carbon dioxide in presence of starch accelerated the rate
of conversion slightly. Potassium dihydrogen phosphate
had a retarding effect. The rate of conversion was found
to increase with increase in temperature till it reached a
maximum af 49°C, thereafter it decreased. The urease
activity of the rumen liquor was found to be at its maximum
between the pH. values 7 and 9. There was a slight increase
in the conversion of urea with increased urea concentration,
Time of sampling was found immaterial. It is remarked
that the urease activity of the rumen ingesta is great at all
times of the day, whatever the time of feeding, and remains
so little affected by relatively large amounts of urea, that-
all the urea over likely to be fed, even to a high yielding cow
in full lactation, will readily be converted to ammonia within
one hr. The inhibitory effect of sodium fluoride, quinone,
cysteine, boric acid and borax on the urease activity of the
rumen liquor was also studied. Toluene was found to be
without effect. It is pointed out that the urease activity
of rumen liquor is similar to urease from jack-bean meal,
and that the enzymes from these two very different sources
have much in common and may be identical.
The third article deals with the conversion of ammonia
to protein in the rumen. Here again, incubation of rumen
contents was carried out under a variety of different condi-
tions and with different substances. The microbiological
condition of rumen ingesta was found to remain practically
constant during the first 2-4 hr. incubation. During this
period of incubation the non-protein nitrogen of the medium
diminished while the total nitrogen remained unchanged,
suggesting that synthesis of protein took place. Control
experiments were carried out with bran and oats, fæces
and soil, but no change in the non-protein nitrogen was
found during the first three hours of incubation. The amount
of synthesis occurring in two hours in the presence of 0.3 gm.
starch per 100 gm. rumen liquor was usually equivalent to
about 8 mg. nitrogen per 100 gm. rumen liquor. A study
of the influence of sodium fluoride, quinone, boric acid,
borax, toluene, temperature and the effects of filtration and
fractionation by centrifuge on the synthesis of protein re-
vealed that, when rumen liquor is incubated with starch
and urea at 39°C, the nitrogen metabolism of the system
involved both synthetic and hydrolytic processes which
probably proceed simultaneously. These processes are mi-
crobiological in origin and the equilibrium between them is
very readily changed, so that either synthesis or hydrolysis