Practical Development of Genetically Engineered Animals and Human
Disease Models. Laboratory Animal Science 47 (2): 113.
Transgenic (Tg) mice were first produced by Gordon in 1980. Tg
animals are considered more useful than the conventional mutants in many
research areas. Researchers and scientists must make sure they adhere to
strict guidelines in the development of Tg mice. For animal
models to be useful they must be defined The physiological and pathological
phenotypes which resemble those in humans must have genetic cause identical
to that in humans. the usefulness and limitations of the animal as
a model must be defined. The TgPVR21 (which is useful as a model
for neurovirulence of oral polio vaccine) mice are used to serve as an
example of the development of a physiological quality standards, followed
by the establishment of a supply system. 2. usefulness and limitations
of the Tg mice are evaluated and Tg strains of the animal model are established.
3. establishment of integrated in vivo experimentation systems using
defined animals models so that the Tg mice can be used effectively to achieve
the final goal of their development. The process of standardizing
lab animals is based on strict quality control. 3 factors in quality
control are: a. establishing reference strains with defined genetic
background and with a definite microbiological status b. monitoring system
to ensure that quality is maintained c. Preservation of reference
strains. The first step in the defining process is done by lab animals
science groups and their role is to establish Tg mice as a standardized
lab animal. Next researchers determine usefulness and limitations
on the basis of comparison with human diseases. The successful development
of TgPVR mice has served as a excellent example of how Tg animals can be
useful animal models for human disease.
No questions
Development of a Neurovirulent Testing System for Oral Poliovirus
Vaccine with Transgenic Mice. Laboratory Animal Science 47 (2): 118.
Only primates are susceptible to all three serotypes of poliovirus.
It takes 100 monkeys for each trivalent vaccine batch repeated at least
three times. Oral poliovirus vaccine (OPV) wild-type Leon/37 strain,
Sabin 3 vaccine strain, and a substantially de-attenuated clone of the
vaccine virus isolated from stool were evaluated. Alternatively and
recommended by World Health Organization (WHO), Transgenic mice carrying
the gene for human poliovirus receptor (PVR) were developed for replacing
monkeys for OPV testing. TgPVR21 mice inoculated in the spinal cord
were as sensitive as monkeys (flacid paralysis, histologic lesions) in
discriminating between type-3 and type-2 OPV lots that were tested by the
monkey neurovirulence test. But Each OPV lot contained neurovirulent
revertants in the viral genome. More revertants would correlate to
failure to the monkey neurovirulent test. Spinal-cord-innoculated
TgPVR21 mice provide a suitable model for evaluation of the neurovirulence
of type-3 and type-2 OPV. The established production of TgPVR mice,
their pathogen-free health status, and lower cost relative to monkeys make
them highly appealing for the neurovirulence testing of OPV.
Questions:
1- What is the traditional method used to assay safety and consistency
of Poliovirus vaccine?
a) Polymerase Chain Reaction
b) Restriction Enzyme Cleavage
c) Monkey Neurovirulence Test
d) Transgenic Mice Neurovirulence Test
2- T/F. TgPVR21 mice provide a suitable model for evaluation of the
OPV neurovirulence?
Answers:
1- c)
2- F. Only for type-3 and type-2 OPV
Rapid Carcinogenicity Testing System with Transgenic Mice Harboring
Human Prototype c-HRAS Gene. Laboratory Animal Science 47 (2): 121.
The authors contend that there is a need to improve the process
by which the carcinogenic potential of chemicals is identified. One
approach is to develop animal models with increased susceptibility to carcinogens.
One such model is the CB6F1-HRAS2 mouse ( BALB/cByJ x C57BL/6JF1 TgN(HRAS)2).
This is a transgenic mouse that carries the human prototype c-HRAS gene.
The HRAS2 gene was selected for insertion because it is a proto-oncogene
and activated ras genes can be observed in ca. 30% of human tumors. The
transgenic mice express the HRAS gene product at levels 2-3 X greater than
non-transgenics and was therefore expected show greater sensitivity to
carcinogens. This paper summarizes some of the preliminary studies done
using this model to test a variety known carcinogens. The authors conclude
that in general, the CB6F1-HRAS2 mouse can be expected to have a more rapid
onset and a higher incidence of more malignant tumors than their non-Tg
controls. They did note two important caveats to this general statement.
First, susceptibility to certain tumors in mice is under control of multiple
genetic loci. The presence of the HRAS2 gene may not significantly increase
the susceptibilty of the Tg mouse to a particular type tumor if the background
strain (BALB/c and C57BL in this case) are already genetically resistant
to that tumor. Secondly, negative control studies remain
to be done. In other words, it has to be demonstrated that the Tg mice
do not respond negatively to known non-carcinogens (are they oversusceptible?).
QUESTION: True or False Mutation of a proto-oncogene converts
it into an oncogene which will transform the normal cell into a cancer
cell.
ANSWER: False, Proto-oncogenes may be converted to oncogenes
by a variety of mechanisms including mutations, gene amplification, chromosome
rearrangements, and gene recombinations. The presence of an oncogene does
increases the susceptibility of the cell to other cancer inducing factors
but it is unlikely that a single oncogene can induce cancer by itself.
Activated and Inactivated Renin-Angiotensin System in Transgenic
Animals: From Genes to Blood Pressure. Laboratory Animal Science
47 (2): 127.
Well-written review of how
transgenic mice and rats have been used to further understanding of how
the renin-angiotensin system affects blood pressure. Recall that the kidneys
produce renin, which cleaves angiotensinogen produced by the liver to form
angiotensin I. This is further converted to angiotensin II by angiotensin
converting enzyme (ACE). The results are vasoconstriction, thirst,
catecholamine release and smooth muscle cell hypertrophy. There are several
angiotensin II receptors which are divided in subtypes AT1 and AT2, distributed
in many tissues.
Early on, transgenic rats
and mice were created with overexpression of renin and/or angiotensinogen,
with resulting high blood pressure. In general, when the genes were expressed
in the adrenals, blood vessels or liver the effect on blood pressure was
present, whereas when expressed in the brain, kidney or lymph node it was
not.
Next, human renin and angiotensinogen
were placed into transgenic mice. Both human genes must be expressed
for blood pressure to be affected, an indication of the species-specificity
of the products. These animals may be useful in drug testing.
Knock-out mice have also
been made which produce no angiotensinogen, and homozygotes have lower
blood pressure. Next, knock-outs for the receptors were made, and have
shown that AT1 and AT2 have somewhat counteracting effects as well as they
can regulate CNS functions such as thirst and movement. One future goal
is to use transgenic animals to determine the exact gene loci in humans
responsible for essential hypertension.
Questions
1. True/ False: Transgenic mice which overexpress human renin will
have low blood pressure.
2. True/False: The main target organ for the final product of the renin-angiotensin
system is the brain.
Answers
1. False, for two reasons. First, angiotensin causes elevated blood
pressure, not lowered blood pressure. Second, both renin and angiotensin
must be of the same species type to have an effect upon blood pressure;
therefore both gene products must be present to increase pressure.
2. False. The main target is the vascular smooth muscle insofar as
blood pressure is concerned, but there are many effects of angiotensin:
vasoconstriction, aldosterone secretion, catecholamine release, thirst,
prolactin and corticotropin release, hypertrophy of vascular smooth muscle,
and possibly even development and maintenance of kidney morphology.
Pathogenesis of Sendai Virus Infection in the Syrian Hamster. Laboratory
Animal Science 47 (2): 132.
Sendai infections occur naturally in laboratory species including mice,
rats, hamsters and guinea pigs. Seroconversion is used as a criteria for
Sendai viral infections in the hamster. Although reports of mortality in
neonatal Syrian and Chinese hamsters are attributable to Sendai virus most
reports indicate only subclinical infection occurs in the Syrian hamster.
A few published reports look at Sendai infections in hamsters. One previous
study compared pulmonary lesions in Sendai inoculated hamsters and hamsters
treated with immunomodulating drugs. Cyclophosphamide-treated hamsters
succumbed to the virus with extensive lesions while methylprednisolone-treated
hamsters appeared to be protected against pneumonic lesions. This paper
describes the experimental infection of 6-8 week old Syrian Hamsters by
intranasal inoculation of Sendai virus to study the changes in the upper
and lower respiratory tract. The only gross necropsy changes were
noted early (5-7 days post inoculation (PI)). These were interpeted as
pneumonitis and described as dark pink to tan mottling at the hilus of
the lung and extending to adjacent parenchyma. Histologically early changes
were seen in the trachea and respiratory epithelium of the nasal turbinates.
These were described as hyperplasia to cytoplasmic vacuolation and degeneration
of scattered epithelial cells. Edema in the submucosa with scattered
neutrophils was noted. After day 5 there was marked hyperplasia of the
respiratory tract epithelium in the nasal turbinates and trachea. After
day 7 the lesions were seen in the lower respiratory tract as well as the
upper respiratory tract. Viral antigen was detected from day 3 PI
and seroconversion from Day 7 PI. It was concluded that Syrian hamsters
are susceptible to Sendai viral infection and rapidly seroconvert
after exposure. The lack of clinical signs in immunocompetent hamsters
after infection has been reported previously. Viral replication was limited
to the airways and the nature and intensity of the lesions are similar
to reports of Sendai infection of mice. The effects of Sendai virus on
immune response and macrophage function was not determined.
Questions:
1. Sendai virus is associated with clinical signs in immunocompetent
young adult Syrian hamsters. T F
2. Syrian hamsters seroconvert after exposure to Sendai virus. T F
3.Sendai virus is
a. paramyxovirus
b. corona virus
c. parvo virus
d. adenovirus
4. Hamsters treated with __________ succumbed to the Sendai viral infection
with extensive pneumonic lesions.
a. methylprednisolone
b. levamisole
c. acetylcysteine
d. cyclophosphamide
Answers:
1. F
2. T
3. a
4. d
Hepatic Hemosiderosis in Common Marmosets, Callithrix jacchus:
Effect of Diet on Incidence and Severity. Laboratory Animal Science 47
(2): 138.
Hepatic hemosiderosis is the deposition of iron pigment, hemosiderin,
within the liver. It is a common finding in marmosets and other New
World monkeys. Although hemosiderosis is considered to be an incidental
finding, the authors found 100% incidence of hepatic hemosiderosis in adult
marmosets from a colony used exclusively in behavioral research and was
considered to have contributed to the terminal wasting syndrome encountered
in the colony's older marmosets. The cause was thought to be the
diet and a study was designed to determine the effect a high iron diet
had on hepatic hemosiderosis. 13 common marmosets (Callithrix jacchus),
7 males and 6 females ranging from 17 months to 3 yrs. They were housed
in breeding pairs and there were 4 sibling groups. Physical exams, baseline
hematology, serum biochemical analysis, serum iron conc., total iron-binding
capacity (TIBC), % transferrin saturation (%TS) and percutaneous liver
biopsies were performed at the start of the study. Liver biopsy tissue
was analyzed for iron content and the rest was used for histopathology
staining sections with H & E and Mallory's Prussian blue method for
iron. Serum analyses occurred at 6 months with liver biopsies for
iron quantification at necropsy or 13 months. Two nutritionally balanced,
open-formula, natural-ingredient marmoset diets were gradually introduced
over 2 months. Diets had identical nutrient concentrations except
for iron. Diet for low iron contained 100 ppm iron, the high iron
diet contained 500 ppm iron for the first 8 months and was then switched
to 350 ppm because of the death of a monkey from liver iron accumulation.
The low iron cohort experienced a mean decrease in liver iron content of
621 ug/g and the high iron cohort experience a mean increase of 6,545 ug/g.
There was no significant difference in hematocrit, serum iron concentrations,
%TS, TIBC and weight gain/loss among cohorts. In all monkeys, there
was a small amount of granular material in hepatocytes confirmed to be
iron by Prussian blue at baseline. In the high iron cohort, liver
samples taken at necropsy had abundant dark, granular pigment confirmed
to be iron by Prussian blue within hepatocytes. The first death in
the study occurred in a high-iron fed male on the 500 ppm diet for 7 months.
It had intermittent diarrhea and weight loss and died of acute necrotizing
colitis from E. coli. They concluded from the study that dietary
iron can directly influence hepatic iron concentration in marmosets and
is the cause of hepatic hemosiderosis. Marmosets fed the high-iron
diet had a mean increase of 279% in liver iron and those fed low-iron diets
decreased by 67%. Diets containing as little as 350 ppm iron can
cause substantial iron accumulation. 4/7 marmosets (57%) fed high-iron
diet died compared to 1/6 (17%) in the low-iron cohort. All monkeys
who died in the high-iron cohort had liver iron content exceeding 10,000
ug/g. Middle aged or older human males especially will get hereditary
hemochromatosis and experience myocardiopathy, DM, arthritis, testicular
atrophy and hepatic cirrhosis when hepatic iron content exceeds 10,000
ug/g. Individuals can't down-regulate iron absorption and absorb
dietary iron in excess of physiologic need. Organ damage is attributed
to iron-mediated release of free radicals, which causes lipid peroxidation
of the cellular membranes. Affected individuals may also have immune
dysfunction and increased susceptibility to infection. Some marmosets
may have increased susceptibility to iron overload and there may be a hereditary
component. A diet low in iron can prevent or reverse iron overload.
Marmosets diets should be formulated to meet the National Research Council's
recommended dietary iron value of 180 mg/kg diet.
Conclusions: Marmosets are useful animal
models of human hereditary hemochromatosis. Feeding marmosets a diet
high in iron can cause hepatic hemosiderosis with 100% mortality in marmosets
with liver iron content >10,000 ug/g. Future study needed to confirm
hemosiderosis as an important and preventable cause of early mortality
and a confounding factor in research.
Questions:
1) Which stain is used to confirm that granular golden brown
pigment seen in hepatocytes is iron
2) What is the hepatic iron content that has been shown to be
associated with death?
3) What is the commercial diet listed to have the lowest iron
content?
Answers:
1) Prussian blue
2) liver iron content 10,000 ug/g
3) Zu/preem canned marmoset diet (Hill's ) 20 ppm
others: New World Primate Diet 5040
(PMI Feeds, Inc.) 381 ppm; NIH-48
marmoset diet (Zeigler Bros.) 380 ppm
Development of a Murine Hypothermia Model for Study of Respiratory
Tract Influenza Virus Infection. Laboratory Animal Science 47 (2): 143.
LD50 has been used as a method of determining the relative virulence
of a pathogenic organism or the toxicity of a particular substance in animal
models. Determination of LD50 may take weeks and subject animals to prolonged
pain and suffering. In this study the authors developed a murine hypothermia
model that could potentially be used to substantially reduce the time and
extent of suffering inflicted on experimental animals, and may therefore
be a more humane alternative to LD50 determinations. A mouse adapted influenza
A virus was used to infect groups of BALB/c mice via the intranasal route,
and the LD50 was determined. Rectal temperatures of the infected mice were
monitored daily, and survival rate was determined at day 14 after infection.
In mice that developed hypothermia, with body temperature of 32 C or lower,
morbidity and mortality inevitably occurred. In this study the LD50 and
the 50% hypothermia-inducing dose (HID50) were compared and found to be
the same. Use of hypothermia may be preferable to death as an endpoint
for the LD50 particularly because the fatal hypothermic temperature (FHT)
can be determined days earlier that death, especially during days when
maximal suffering would be experienced.
Questions:
1. What is LD50 and what is it used for?
2. HID50 is an acronym for what?
3. Name several advantages of using HID50 over LD50?
4. FHT is an acronym for what and what temperature is considered, in
this study, to represent the FHT?
Answers:
1. Lowest dosage of test substance which is lethal to 50% of test subjects.
Used as a measure of relative virulence or toxicity.
2. 50% hypothermia-inducing dose
3. Reduced pain and suffering to experimental animals, shorter studies,
less cost, reduction of cannibalization of animals that die in cage thus
less risk of cross infection to healthy mice, and the elimination of the
foul odor of dead animals.
4. Fatal Hypothermia Temperature; 32C
Spontaneous Leydig Cell Tumors in Inbred Laboratory Mice. Laboratory
Animal Science 47 (2): 148.
Although Leydig cell tumors are common in dogs and in some rat strains,
they are extremely rare in mice, with a spontaneous incidence of less than1%.
This paper was a case series of Leydig cell tumors in a large BALB/cJ
breeding colony. Six Leydig cell tumors were identified in
6,500 male mice necropsied over a period of 8.5 years. All tumors developed
spontaneously in BALB/cJ and BALB/cByJ inbred mice. When submitted for
necropsy, affected mice were 8 to 9 months old. The incidence was calculated
to be 5.5 per 100,000 males retained as breeders. Tumors were unilateral,
with no predilection for right or left testis, Histologically all Leydig
cell tumors were well differentiated and of the solid, diffuse type.
Leydig cells (or interstitial cells) produce testosterone
and estrogens, and are required for male reproductive function.
Leydig cell tumors are divided into three types: solid, cystic vascular,
and psuedoadenomatous. LEydig cell tumors can be induced experimentally
in susceptible mouse strains (BALB/c) by the administration of estrogens.
Questions
Q1. T/F Leydig cell tumors are common in BALB/cJ mice
Q2. What type of Leydig cell tumor was seen in all 6 mice reported
on in this series
Q3. How can Leydig cell tumors be induced experimentally in mice?
Answers
A.1 F. They are still very rare (5.5/100,000)
A2. solid
A3 administration of estrogens
Comparison of the the Hemodynamic and Hematologic Toxicity of a Protamine
Variant After Reversal of Low-Molecular-Weight Heparin Anticoagulation
in a Canine Model. Laboratory Animal Science 47 (2): 153.
This article compared the standard sulfate and protamine variant +18RGD.
They are agents that reverse standard unfractinated heparin and low molecular
weight heparin (LMWH). Multiple hemodynamic factors were monitored
such as, mean arterial pressure, cardiac output, and oxygen consumption.
Standard hematologic studies including monitoring thrombocytopenia were
also done.
The aurthors found that the protamine variant was
less toxic, induced less thromocytopenia, and was more effective
as an anitcoagulant reverasal agent than the standard protamine sulafate.
The study also indicated that the dog may be a useful model for investigating
important hemodynamic hematologic and coagulation parmeters during reversal
of LMWH anticoagulation by use of synthetic protamine variants.
Questions:
1. The advantages of LMWH over standard heparin are:
A. greater or equal antithrombotic effect with minimal bleeding
B. better bioavailablity
C. decreased need for clinical laboratory monitoring
D. prolonged plasma 1/2 life
E. all of the above
2. What is the only FDA approved agent for reversal of heparin anitcoagulants?
Answers:
1.E
2. Protamine sulfate
Nitric Oxide Inhibition Causes an Exaggerated Pressor Response in
Yucatan Miniature Swine. Laboratory Animal Science 47 (2): 161.
The involvement of nitric oxide (NO) in cardiovascular and renal function
was evaluated in anesthetized Yucatan swine. NO is a endothelium
derived vasoactive compound that may influence vascular tone. Blockage
of NO by use of L-arginine analogs ( L-NAME ) increase blood pressure,
increased renal vascular resistance, decreased renal blood flow, glomerular
filtration rate, and sodium and water excretion. Therefore NO is
an important vasodilator that regulates systemic and renal vascular tone.
The exaggerated pressor response that is experience when NO is acutely
blocked by L-NAME is believed to regulated by the sympathetic nervous system.
Questions
1. Which of the following is not effected by blockage of Nitric
Oxide:
a. Glomerular filtration rate
b. Water and Sodium excretion
c. Blood pressure
d. None of the above
2. What is the swine's gestation length in days?
3. Name the vessel in swine that empties into the coronary sinus?
Answers
1. d
2. 114
3. Left azygous
SWR: A Inbred Strain Suitable for Generating Transgenic Mice.
Laboratory Animal Science 47 (2): 167.
SWR and SWRxDBA/1 females
were found to be suitable embryo donors for the development of transgenic
mice. Most transgenic mice are produced using C57BL/6 F1 and
F2 hybrids as the egg donors, with FVB/N also being used. Advantages
of using SWR are their defined genetics, large embryos with prominent pronuclei,
and good production of viable embryos (comparable to the B6 background
mice).
In the study discussed,
DBA/1 mice were needed to generate a strain susceptible to rheumatoid arthritis.
The strains tested were DBA/1, SWR, (DBA/1 x SWR)F1, and (SWR x DBA/1)F1.
The SWR females were found to be prolific ovulators in response to exogenous
hormones with oocyte numbers comparable to (B6 x C3H)F1 mice. SWR
and (SWR x DBA/1)F1gave the desired embryos while (DBA/1 x SWR)F1 did not,
therefore the trait appears to be one of the SWR female and independent
of the genotype of the fertilizing spermatozoa. Resistance to lysis
in the SWR and ( SWRxDBA/1)F1 was similar to that for B6 based embryos.
The FVB mice, although suitable for production of embryos, are less well
genetically characterized than the SWR mice. SWR hybrids have an
additional advantage in that the SWR female can be crossed with a male
carrying the desirable trait, thus less backcrossing is needed to establish
the transgene on the desired genetic background.
Questions:
1. What strain of mice is the most used background for transgenic
mouse production?
2. List desirable characteristics for the oocyte donor and embryos.
3. What other strains are used in production of transgenic mice
according to this article?
Answers:
1. C57BL/6
2. Many oocytes produced in response to exogenous hormones.
Good viability of embryos.
Large embryos.
Prominent pronuclei.
Genetically defined.
Embryos resistant to lysis after manipulation.
3. FVB/N, SWR
Training a Large Number of Laboratory Mice Using Running Wheels and
Analyzing Running Behavior by Use of a Computer-Assisted System. Laboratory
Animal Science 47 (2): 172.
Osteoarthritis is a group of diseases with multiple causes that ultimately
leads to destruction of diarthrodial joints. Physical exercise contributes
to the development of osteoarthritis. This phenomenon is apparent
for mice, which are susceptible to developing spontaneous osteoarthritis.
Given this, the authors constructed a system as a tool for osteoarthritis
research which provided experimental mice, either normal or transgenic,
with exercise and simultaneously analyzed their running behavior.
The system designed was a running wheel system suitable for voluntarily
exercising large numbers of mice. Photoelectric sensors were attached
to the cages, sensors were interfaced with PC's, two custom-made programs
were utilized to gather data, results were transferred to spreadsheet and
statistical analysis programs. The system was able to analyze mice
for intervals of 23 hours at a time. It was noted that activity and
noise levels in the room affected animals running rhythm. This study
presents a viable voluntary method for long term physical exercise in the
mouse.
No questions
Breeding of Bonnet Monkeys (Macaca radiata) in Captivity. Laboratory
Animal Science 47 (2): 180.
The purpose of this article was to look at the effectiveness
of breeding in the South Indian bonnet monkey. The welfare of these
monkeys was evaluated based upon their decreasing population in the wild
as a result of illegal exportation and the destruction of their natural
habitat. This article looked at data obtained thru breeding
and their use in biomedical research over the last 20 years.
Five main points:
1) Bonnet macaques don't exhibit sexual skin changes, as do rhesus
monkeys.
2) Bonnet macaques can breed throughout the year (even though most
births occur Jan - April with breeding during the rainy season, July -
October. Maintaining a humidity of 55 to 65% and temperatures between
24 and 26 C reduced amenorrhea significantly. Bonnet macaques can be bred
immediately post-quarantine.
3) Bonnet macaques have implantation bleeding between days 28 and 36
of the cycle, which is much brighter red in color than normal menstrual
bleeding.
4) Gestation period for bonnet monkeys = 161 - 174 days, with a 2:1
male-to-female ratio of offspring
5) Weaning of bonnet macaques at 6 months of age usually resulted in
the mom/female returning to cyclicity.
The oldest females of this species successfully bred in
captivity have been as old as 15 years of age. This species has been
used successfully in research to test the anti-fertility effects of Vicoa
indica. Other areas include gastroenterology, nutrition, endocrinology,
neurosurgery and experimental medicine. The Bonnet macaque is an
endangered species.
Questions:
1. Give the genus/species name of the Bonnet macaque.
2. What is the major difference in sexual skin changes in rhesus
monkeys vs. Bonnet monkeys ?
3. Increasing (estrogen, progesterone) concentration inhibits
mucous secretion.
Answers:
1. Macaca radiata
2. Rhesus have sexual cycle skin changes, whereas Bonnet macaques
do not.
3. Increasing progesterone concentration inhibits mucous secretion.
Measurement of Flow Rates Through Aortic Branches in the Anesthetized
Rabbit. Laboratory Animal Science 47 (2): 184.
The volumetric flow rates, mean and pulsatile, in the aorta and its
major branches were measured in nonfed, anesthetized rabbits, using a transit
time Doppler ultrasound flowmeter. Anesthesia was maintained with
isoflurane, and a vasodilator was applied topically during the measurements
to avoid introducing additional flow resistance due to vasoconstriciton.
The cranial mesenteric and celiac arteries received the bulk of the aortic
flow, (mean +/- SD) 29.5 +/- 6.6% and 23.3 +/- 5.8%, respectively, for
mean flow. The brachiocephalic artery received as much as 14.7 +/1
3.2%, while each of the other branches received a considerably smaller
fraction: 7.1 +/- 2.5% for the left subclavian artery, 6.2 +/- 2.5%
for each of the two iliac arteries. Flow divisions were nearly the
same in paired vessels. Peak pulsatile flow divisions were similar
to their steady flow counterparts in the brachiocephalic, left subclavian,
celiac, and cranial mesenteric arteries, but were smaller in the renal
and iliac arteries, although the difference was not statistically significant.
Reverse flow from one or more of the branches back in to the aorta occurred
in diastole in seven of eight rabbits studied.
No questions
Blood Sampling Technique for Measurement of Arginine Vasopressin
Concentration in Conscious and Unrestrained Rats. Laboratory Animal Science
47 (2): 190.
Plasma arginine vasopressin (ASV) concentration is said to change
in response to variuos procedures used for blood collection (stress) In
this study a new blood collection technique was compared to two generally
accepted methods (decapitation and routine jugular vein cannula)
by mesuring plasma AVP, glucose and corticosterone concentrations in blood
samples collected with each method. Decapitation: some rats were decapitated
within 5 sec after the body was picked up. Routine jugular vein cannula:
rats were anesthetized and after a skin incision the cannula was put into
the right jugulare vein. Swivel group (the new method used): two
h prior to blood sample collection, an extension catheter was attahed to
the free end of the jugular vein cannula. The free of the extension catheter
was then passed thruogh a hole in the center of the lid of the animal
cage. Rats, were allowed to move freely within the cage due to the bearing
at the cage top. Results: the new blood collection technique described
appears to induce the least stress in the rat because the plasma corticosterone
, plasma AVP and glucose concentrations were found to be the lowest
by using this new method
Questions
1.- T/F. Plasma AVP concentration is higher than
physiologic range immediated after decapitation?
2.- T/F. The routine jugular vein cannula dont need anesthesia
Answers:
1.- T
2.- F.
Differentiation of EF-4 Biovars by Analysis of Methicillin Resistance.
Laboratory Animal Science 47 (2): 194.
Eugonic fermenters (EF-4) bacteria are a group of glucose-fermenting,
gram-negative bacilli which can be isolated from the oral cavity of dogs,
cats and rodents. These bacteria can be the etiology of a syndrome in humans
characterized by wounds with cellulitis, erythema, abcessation, and low-grade
fever commonly referred to as dog- or cat-bite fever. These bacteria have
been implicated as the etiologic agent of focal necrotizing pneumonia of
cats. Two distinct biovars have been differentiated by biochemical profile
and electrophoretic activity - EF-4a and EF-4b. This paper further characterizes
these biovars on the basis of methicillin resistance/susceptibility. EF-4a
is resistant to methicillin in both disc diffusion and minimum inhibitory
concentration (MIC; breakpoint =/> 64 mcg/ml) test while EF-4b is susceptible.
Also, EF-4a but not EF-4b have been implicated as the etiologic agent in
both human and feline disease.
QUESTIONS:
1) EF-4 (eugonic fermenters) are classified as what type of bacteria?
2) EF-4a are methicillin- _________________ and are the etiologic agent
of _________________ in humans.
ANSWERS:
1) glucose-fermenting, gram-negative bacilli
2) resistant; cat-bite disease (or dog-bite disease)
Asymptomatic Adenoviral Respiratory Tract Infection in Guinea Pigs.
Laboratory Animal Science 47 (2): 197.
The authors report three cases of what they call "subclinical" adenoviral
respiratory tract infection although there remains the possibility that
the animals may have been killed while in the early stages of the disease.
Adenoviral pneumonia of guinea pigs is generally characterized by an acute
course, low morbidity, and very high mortality (up to 100%). Histologic
findings of necrotic bronchitis and bronchiolitis with large basophilic
intranuclear inclusion bodies in epithelial cells are distinctive, as is
infiltration of the alveolar septa by lymphocytes, macrophages, and neutrophils.
The authors suggest that adenoviral infection in guinea pigs may be similar
to that of other species such as cattle in which serologic surveys indicate
wide-spread distribution of infection, but little overt disease.
No questions
Body Composition of the 12-Week-Old Piglet Studied by Dissection.
Laboratory Animal Science 47 (2): 200.
This study measures the body composition of 20 20 to 25 Kg Swedish
Landrace x Yorkshire pigs. The authors were very detailed in their description
of how organs and tissues were collected and weighed and the paper shows
2 charts detailing the percentage of each organ and tissue as it pertains
to total body weight.
Question: Give the taxonomy for the domesticated pig.
Answer:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Suidae
Subfamily: Suinae
Genus: Sus
Species: scrofa
Birth of Normal Young by Microinsemination with Frozen-Thawed Round
Spermatids Collected from Aged Azoospermic Mice. Laboratory Animal Science
47 (2): 203.
In some azoopermic animals and humans, spermatozoa may not available
from testes, and therefore spermatid injection is expexted to help these
cases. The study reported was undertaken to examine the possibility of
producting mouse pups, using round spermatids from aged azoopermic mice
and cryopreserved for 1 to 20 weeks. 33 months old males C57BL/6NCrj
were sacrificed , round spermatids were collected and freezed.A B6D2F1
female mice were superovulated and its oocyte swere microinjected with
a frozen thawed round spermatid. After 24 of culture normal two cell embryons
wre transferred into the SicICR female mice.
About 75% of oocytes survived micromanipulation
and most developed to the two cell satge. Round spermatids are the
youngest haplod male germ cells, in which postmeiotic modifications have
not begun. Injecting spermatids into oocytes is a more direct way to transmit
male DNA to the oocytes than fertilizing oocytes with mature spermatozoa.
QUESTIONS:
1.- Were round spermatids from aged mice with idiopatic
azoospermia able to participate in normal embryo development? F/T
2.- Round spermatids were cryopreserved for 1 to 20 months. F/T
ANSWERS:
1. T
2. F (for 1 to 20 weeks)
Fatal perforating intestinal ulceration attributable to Flunixin
Meglumine overdose in rats. Laboratory Animal Science 47 (2): 205.
This paper describes the consequences of an inadvertant Banamine overdose
in rats. The dose given was 11mg/kg (calculated appropriate dose
was 1.1mg/kg). The Banamine was diluted incorrectly. Presenting
signs were inappetence and depression extending beyond the immediate postsurgical
period (neuroendocrine study). Gross necropsy showed:
diffuse, severe peritonitis; multiple adhesions; perforated ulcers
of ileum, jejunum, and cecum (not stomach or duodenum), sometimes with
abscesses; GI distension with gas and ingesta. These findings were
confirmed on histopath. Differentials for the gross findings included
Tyzzer's, Salmonella enteriditis, Streptococcus pneumoniae, corynebacterium
kutscheri, IP chloral hydrate anesthesia, or poor IP technique.
Questions:
1) T/F Side effects of NSAIDs are caused by their ability
to inhibit
cyclooxygenase and a subsequent decreased production of prostaglandins.
2) Which of the following is NOT a side effect expected with
NSAID use?
(a) GI ulceration
(b) Heinz body anemia
(c) Increased platelet aggregation
(d) Nephrotoxicosis
(e) Increased gestation time
Answers:
1) True
2) c
Immunologic and Ultrastructural Characteristics of TCell Lymphoblastic
Lymphoma Associated with Mast Cell Infiltration in a Wistar Rat. Laboratory
Animal Science 47 (2): 209.
This note describes one case of lymphoblastic lymphoma which is rare
in rats but more common in mice. Clinical signs were dyspnea, ocular
discharge, anorexia and weight loss. Necropsy revealed disseminated
tumors with ledions present in thymus, GI tract, kidney, spleen, liver
and lymph nodes. Histologically, the tumor cells were arranged in
sheets with macrophages and Mast cells interspersed. The cells were
positive for CD 3,4,5,and 8, but negative for a B cell marker. The
final diagnosis was malignant lymphoblastic lymphoma of Tcell origin in
multicentric form. The authors note that Mast cell infiltration of
lymphomas has been reported in mice and humans, and speculate that they
may be chemotactically attracted by factors released by the neoplastic
lymphocytes.
Questions:
1. What special stain is used to demonstrate Mast cells?
2. Mast cells bear surface receptors for the Fc portion of IgE.
When
the bound IgE is crosslinked by a multivalent antigen, mast cells
are
activated and release vasoactive amines (histamine and serotonin) and
the cytokines ____ and _____ .
Answers:
1. Toluidine blue.
2. IL4 and TNFalpha
Reference: Immunobiology, Janeway and Travers