Mice fed radiolabeled protein by gavage show sporadic passage of
large quantities of intact material into the blood, an artifact not associated
with voluntary feeding. Contemporary Topics 38 (5): 18.
This article raises an interesting question. Can the pharmacokinetics
of proteins (test articles) administered by oral gavage in rodents be compared
with oral administration in humans?
This study was designed to determine whether a small portion of orally
ingested Bovine B2-microglobulin (BovB2-M) could pass, intact, into the
mouse circulatory system. Initial experiments feeding I-labeled protein
by gavage indicated that intact BovB2-M appeared rapidly and in significant
amounts in the blood, as demonstrated by sodium dodecyl sulfate-polyacrylamide
gel electrophoresis (SDS-PAGE). However, this result was sporadic, occurring
only in 1/3 of all animals (27 of 71 mice).
When BovB2-M was combined with a larger protein, bovine serum albumin
(BSA) and fed by gavage, surprisingly, large fragments of BSA appeared
in the plasma whenever the BovB2-M appeared. Again, this occurred only
in 1/3 of the animals.
Other experiments administering BSA and BovB2-M by voluntary drinking
demonstrated plasma presence of both proteins but in smaller quantities.
The conclusion: Gavage feeding in mice could occasionally lead to 'micro
aspiration' and entrance of test article directly into circulation via
the lungs rather than through the gastrointestinal tract. Gavaging is inherently
a complex technique, the success of which depends on several factors, whereas
voluntary feeding is able to avoid virtually all of these difficulties.
QUESTIONS:
1. Which of the below could be associated with oral gavage in rodents?
a. Impaired ability of the animal to swallow
b. Possible overfilling of the stomach
c. Regurgitation/Asiration
d. Damage to the esophagus
e. Highly stressful, could modulate immune response
2. Advantages of voluntary feeding: (Assuming palatability)
a. Animal swallows normally
b. No possibility of esophageal damage
c. Voluntary feeding makes regurgitation unlikely
d. Overfilling not possible
e. Minimal stress to animal
ANSWERS
1. ALL OF ABOVE
2. ALL OF ABOVE
Effective strategy for evaluating tactile enrichment devices for
singly cages macaques. Contemporary Topics 38 (5): 24.
This article out lines a simple method using a time based grading system
and staticial averages to dtermine which devices provide manipulation time
for a specific macaque.
These animals were all single housed and acclimated to the presence of the scorer. Scoring ranged from 1-10 with each number representing approximately a block of 6 minutes. The averages of the time each animal spent with a given device was evaluted over a 12 week period.
The author believed this strategy could be used to meet the regulatory
requirement for environmental enrichment.
Questions
1) The year environmental enrichment was mandated for nonhuman primates.
2) Name three catagories of objects which can be used as enrichment
.
Answers
1) 1991
2) toys, structural devices ( shelve, perches), opportunites for animals
to express species-typical behaviors.
Puzzle feeders and gum feeders as environmental enrichment for common
marmosets. Contemporary Topics 38 (5): 27.
The purpose of the study was to compare the utility of two different
foraging devices (Puzzle-Feeders^Á and gum feeders) as environmental
enrichment for common marmosets (Callithrix jacchus jacchus). Two types
of gum feeders were tested: a feeder made of autoclaved hardwood with holes
drilled in it for injection of acacia gum, and a feeder made from Gumabone^Á
dog toys, with similar holes drilled in it. Puzzle feeders were loaded
with waxmoth larvae, a favorite food item. Marmosets were housed either
individually, in sibling pairs, or in heterosexual breeding pairs. Feeders
were provided either once weekly for 3 hrs (both types of feeders) or continuously
for a period of 5 days (gum feeders only, and only for singly-housed marmosets).
The continuous presence of the gum feeder was to allow for the development
of gouging and scent-marking, which are typical species behaviors in the
wild. Gummivory is thought to provide calcium for an otherwise phosphorus-rich
insectivorous diet.
As might be expected, singly-housed and sibling pairs used the devices
more than heterosexual pairs. Sibling pairs used the feeders most. Most
of the activity involving both types of devices occurred within the first
hour after the device was attached to the cage, perhaps because the supply
of larvae or easily-obtainable gum was exhausted fairly quickly. In the
continuous gum feeder experiment, only one marmoset engaged in scent marking.
Gouging was more obvious on the wooden gum feeders than on the Gumabone
feeders, although during observation periods the rates of use of both types
of gum feeders were about the same. Both puzzle feeders and gum feeders
encouraged species-typical behavior, and reduced sterotyped pacing and
the duration of inactivity.
Questions
1. Which animals appeared to derive the most benefit from both types
of feeders?
2. T or F Gouging is primarily a territorial marking behavior.
Answers
1. The paired siblings used the feeders the most.
2. False--gouging is primarily used to obtain gum from tree, although
the scent-marking behavior is usually in near proximity.
Biomethod for obtaining gastric juice and serum from the unanesthetized
guinea pig (cavia porcellus). Contemporary Topics 38 (5): 32.
It is considered difficult to collect gastric juice and blood samples
from an awake guinea pig (GP); the former is limited by GP oropharyngeal
anatomy (small palatal ostium due to extensive soft palate coverage of
the back of the throat, little room between molars) and the latter (vena
cava, femoral artery, cardiac puncture, retro-orbital puncture) is typically
done under anesthesia. Methods to obtain frequent gastric juice and blood
samples from awake, manually restrained GPs have now been developed. These
techniques can be used in animals of either sex ranging from 2 wk to 18
mo of age. Prior to gastric juice collection, GPs housed on wire should
be fasted 16-24 h.
Fasted animals not kept on wire will eat bedding/feces, thus making
gastric contents too viscous for aspiration. It is recommended that a 5-ml
syringe and a 5- or 6-F infant feeding tube be used for gastric sampling.
Sample collection in the awake GP requires that an assistant restrain the
animal in a vertical position. One hand is around the animal's thorax and
abdomen, with the animal's body held tightly against the assistant's chest
(Figure 1a). The operator loops a strip of 1-in-wide cotton gauze around
the top incisors. Once the gauze strip is secured (Figure 1b), it is given
to the assistant who uses the gauze loop to maintain the animal's head
in extreme dorsoflexion. The operator uses a 2nd gauze strip to control
the lower jaw (Figure 1c) and can now insert the feeding tube. The tube
must be directed down the middle of the buccal cavity or the molars will
chew and damage the tube. Once the tube is down the esophagus, up to 5
mls of gastric juice can be withdrawn (Figure 1d). If the feeding tube
becomes clogged during withdrawal, the syringe should be removed and 1-2
ml of air injected to clear the clog. Using larger feeding tubes can cause
syncope, probably through a vagal response. Once the sample is collected,
pinch off the tube as it is withdrawn so as to prevent backflow of gastric
contents.
Blood collection via the jugular vein requires that the awake GP be
placed on its back in spread-eagle position with an assistant holding the
hind limbs and left forelimb. Most animals will freeze once on their backs,
but can be mesmerized by stroking the animal's abdomen. The operator controls
the animal's head by positioning his/her thumb between the rami of the
mandible, and holds the right forelimb (Figure 2a). In most GPs, the right
jugular vein tends to be larger than the left. It is recommended that a
1-ml syringe with a 24-gauge 5/8-in needle be used for venipuncture. GP
skin is tough and may blunt the needle so additional needles may be needed
should the initial attempt be unsuccessful. The venipuncture site is the
hollow of the right shoulder above the collarbone (Figure 2b). Venipuncture
site preparation only requires swabbing the area with alcohol; no clipping
of the hair is needed. The jugular vein is extremely superficial and can
be entered with the needle inserted in or less. The needle is advanced
slowly toward the left hip until successful positioning for blood collection.
Up to 2.5 ml of blood can be collected via this route. After blood is drawn,
pressure should be applied to the venipuncture site for 2-3 min. It is
recommended that venipuncture by this method be the last procedure of the
day for the animal so as to minimize stress and other complications (hematoma).
Weekly to biweekly blood samples can be collected by this method with no
to minimal morbidity/mortality and distress. This method is not recommended
for multiple small volume sampling on the same day due to risk of hematoma
formation.
Disadvantages of these 2 techniques, compared with performing procedures
on sedated/anesthetized animals, are that they require 2 trained operators.
Also, an awake and fractious animal could bite an operator or cause self-inflicted
trauma if inexpertly restrained. The advantages are that there is no anesthetic
risk to the animal; no additional time is needed for anesthetic induction
or for monitoring anesthetic recovery resulting in shorter procedural times;
and animals appear less distressed by brief manual restraint versus anesthesia.
GPs react less to venipuncture than to IM injections of anesthetics.
The manual restraint described for gastric content sampling may be
useful for other applications such as introduction of an endoscope in an
anesthetized GP and intragastric dosing of awake GPs. The use of gauze
allows finer control of the opening of the mouth and positioning of the
head and neck, thus minimizing risk of injury to the GP and allowing correct
positioning of the palatal ostium. By positioning the animal vertically
rather than sternally as described in other methods for oral dosing in
awake GPs, an operator is better able to collect gastric samples which
are pooled in the dependent part of the stomach and thus more easily accessible
via feeding tube. In the sternal/horizontal position, gastric contents
are spread out over the relatively flat fundus and accumulate in smaller
pools that are less accessible via tube.
QUESTIONS:
1. List two anatomical features of the guinea pig oropharynx that makes
gastric content sampling difficult.
2. Which jugular vein, right or left, tends to be larger in most guinea
pigs and therefore more easily entered for venipuncture? Is the jugular
vein superficial or deep in the GP?
3. What are some advantages/disadvantages of performing the described
techniques vs. performing similar procedures in sedated/anesthetized animals?
4. What are some other applications of the manual restraint used in
gastric sampling of awake GPs?
5. What are some possible complications for the gastric sampling method?
Jugular venipuncture technique?
ANSWERS:
1. a. Small palatal ostium due to soft palate covering most of the
back of the throat.
b. Little room between the molars.
2. Right jugular vein; the jugular vein is extremely superficial in
the GP.
3. Advantages:
a. No anesthetic risk to animal
b. Shorter procedural time due to no time needed for anesthetic induction
and recovery
c. Less distress for the animal due to manual restraint versus anesthesia.
Disadvantages:
a. Requires two trained operators
b. Inexpertly restrained, fractious animal may bite
c. Inexpertly restrained animal may cause self-inflicted trauma (i.e.
hematoma).
4. a. Introduction of an endoscope into an anesthetized GP
b. Intragastric dosing of awake GPs
5. Gastric sampling method:
a. Animal bites off and swallows/aspirates parts of feeding tube
b. Damage to feeding tube if animal chews or bites
c. Syncope if too large a feeding tube is used
d. Unfasted animals or nonfed animals not on wire will have gastric
contents that are too viscous for sampling.
Jugular venipuncture method:
a. Hematoma
b. Self-inflicted trauma
Influence of age on the electrocardiographic waves in Taiwanese Lan-Yu
miniature pigs. Contemporary Topics 38 (5): 36.
Because of the similarities in cardiac vasculature anatomy and induced
swine disease models to people, the Taiwanese Lan-Yu (TLY) miniature pig
has been used as a model in Taiwan since l987. It was of interest to the
authors to determine if the ECG parameters of the developing TLY are comparable
to that of other swine and humans. These swine are also referred to as
TLY small ear pigs. The ECG from these pigs was monitored in an unanesthetized/unsedated
state, with animals slung in a webb stanchion beginning at one day of age
and continuing at 7,14, 21, 30, 60, 90, 120, and 180 days after birth.
Over this time course pigs, averaging 0.6 kg at birth weighed 25 kg at
the 180th postnatal day. The standard bipolar limb leads as well as the
augmented leads (aVR, aVF and aVL) were recorded in all animals.
1. From birth, there was a bimodal response in the Q-T interval, rising
between birth and 7 days and then falling steadily to the end of observations
at day 180. This was correlated with a similar change in the heart rate.
2. There was a significant widening of the QRS complex, with time,
attributed by these authors to increased ventricular mass with age and
slower conduction of current through this mass.
3. There were no significant ECG changes over time when compared to
domestic pigs at comparable ages or neonatal to young pediatric human subjects.
Note From Reviewer:
1. The authors, in one table, compare the polarity of the "P" and "T"
wave to that of infants but use different leads for the comparison then
those used by the cited authors in pediatric patients.
2. Considerable attention is paid to the change in the Q-T interval
and its inverse relationship to heart rate but make no mention of Bazett's
formula for correcting for changes in heart rate.
Questions:
1. Pigs in this study were group housed, six to a pen, measuring 3
x 5 meters. Is this less or more space than required by the Guide for housing
six pigs?
2. In comparison to the negative or positive electrode of the standard
bipolar limb leads, how are the polarities of the augmented limb leads
situated?
3. What is Bazett' s formula for correcting the changes in the Q-T
interval with changes in heart rate?
Answers:
1. This pen measures 15 square meters. Each square meter is 11.11 sq
ft, hence a total of 166.7 sq ft/6 animals or 27 sq ft per animal. For
pigs in this weight range, grouped in numbers greater than 5, the Guide
recommends 6 sq ft per animal.
2. In standard bipolar limb leads, the right front limb is negative
in Leads I and II and the left front limb is negative in lead III. The
left front limb is positive in Lead I and the left rear limb is positive
in leads II and III. In the augmented (unipolar) leads, two limbs, connected
together, are always negative. When the right front limb is positive, the
aVR is recorded. When the left front limb is positive, the aVL is recorded
and when the left rear limb is positive, the aVF is recorded.
3. Bazett's formula for correction of the Q-T interval is: Corrected
Q-T interval = 0.37 x square root of the R-R interval.
Outer cortical necrosis associated with renal artery constriction
in the kidney of a dog. Contemporary Topics 38 (5): 42.
This report describes outer cortical necrosis in the kidney of a dog
with renal artery constriction.
Vascular anatomy of the dog kidney:
· the renal artery divides into interlobar arteries - at the
renal hilum
· interlobar arteries divide into arcuate arteries - near the
corticomedullary junction
· arcuate arteries divide into interlobular arteries which perfuse
the cortex
The renal cortex was arbitrarily divided into 4 zones:
· Zone I = outermost subcapsular cortical area
· Zone II
· Zone III
· Zone IV = innermost juxtamedullary zone
A previous study has shown that decreased renal perfusion pressure
leads to increased absolute bloodflow to zones III and IV and decreased
absolute bloodflow to zone I. Similar changes have been seen with aortic
constriction and a decrease in arterial pressure secondary to hemorrhage.
It has been hypothesized that during compromised renal blood flow,
prostaglandins may cause an increased blood flow to the inner portion of
the cortex preferentially over the outer cortex.
In this case report, a 9-month-old male beagle was to be used in a
future vascular study. During one anesthetic episode, multiple procedures
were performed including:
· implanting a radiotelemetry devise in the right inguinal area
· placing a catheter in the right femoral artery to measure
systemic arterial pressure
· placing a ultrasonic renal flow probe around the left renal
artery to measure renal arterial blood flow
- a silicon wrap was placed around the artery to help secure the probe.
Surgery appeared to be uneventful. Normal renal blood flow value (RBF)
is 92+/- 24ml/min. Twenty-four hours after surgery, the beagle's RBF was
65ml/min. However, 15 days after surgery the beagle's RBF was 19ml/min.
Bloodwork abnormalities included increased PVC (57.2%) and an increased
BUN (19.5mg/dl). Presurgical values were 46.1% and 10.5mg/dl. Due to the
marked decrease in RBF, the dog was euthanized.
Necropsy revealed:
· silicone wrap was constricting the left renal artery
· the left kidney was slightly small (approximately 80% of the
size of the right kidney)
· cortical zones I and II of the left kidney was grayish-white
and firm in consistency with a few dark brown, unaffected areas
· the rest of the kidney appeared grossly normal
Histopathology revealed:
· the grayish-white zone in the outer cortex had diffuse circumferential
tubular epithelial degeneration, necrosis, and mineralization. These changes
were most severe in the outermost cortex
· focal areas had slight interstitial fibrosis and prominent
thickened arterioles and small arteries
· in the outer cortical zone, glomeruli were small with a few
dilated Bowman's spaces
· the inner cortex, medulla, and papilla in this kidney and
the contralateral kidney had no significant findings
The authors believe that these changes are consistent with a mild,
progressive ischemic etiopathogenesis (such as a constricting band around
the renal artery).
These changes are different from acute ischemic insult with resultant
acute tubular necrosis throughout the cortex or from obstruction of an
arcuate artery with resultant wedge-shaped ischemic cortical necrosis.
QUESTIONS:
1) Arrange these vessels in order from most proximal to most distal:
arcuate arteries, interlobular arteries, interlobar arteries, renal artery
2) Constriction of the renal artery will likely result in which gross
finding?
a. Cortical zones I and II appearing grayish white and firm in consistency.
b. Wedge-shaped pale area of the cortex.
ANSWERS:
1) renal, interlobar, arcuate, interlobular.
2) a
Oropharyngeal necrobacillosis with septic thrombophlebitis and pulmonary
embolic abscesses: Lemierre's syndrome in a New Zeland White rabbit. Contemporary
Topics 38 (5): 44.
Lemierre's syndrome is an eponym for an acute clinical condition characterized
by oropharyngeal infection due to anaerobice bacteria leading to septic
thrombophlebitis of the internal jugular vein, with frequent pulmonary
embolic abcesses in humans. In humans, the syndrome is also known as postanginal
sepsis. Although several species of anaerobic bacteria may cause the condition
in humans, Fusobacterium necrophorum is by far the most common anaerobe
isolated from human patients. Fusobacterium necrophorum was isolated from
this reported case of oropharyngeal necrobacillosis with septic thrombobplebitis
and pulmonary embolic abscesses in a New Zealand White rabbit. The clinical
signs, microbiological findings, and pathology associated with this case
closely mimiced that reported in humans. Anaerobic bacteria live as saprophytes
or normal bacterial flora of the oropharynx and upper respiratory, gastrointestinal,
and urogenital tracts. These bacteria can become secondary invaders in
the mucosa, skin, and other tissues damaged by events such as trauma, malocclusion,
retained premolar root, gingival malformations, and/or other synergistic
bacterial infections. Once established, the bacteria proliferate and induce
inflammation or abscesses in local tissues and give rise to septic thrombophlebitis
and embolism in distant organs.
The underlying cause of the disease in this rabbit was thought to be
oral or gingival trauma, followed by F. necrophorum infection or abscess.
F. necrophorum produces several exotoxins and endotoxin which may be collectively
responsible for host tissue necrosis. In ruminants, this bacterium often
causes necrotic stomatitis, gastroenteritis, hepatitis, and footrot. Carnivores
appear to be more resistant to necrobacillosis.
A tenative diagnosis of Lemierre's syndrome can be made on the basis
of clinical and pathological findings and confirmed by isolation of Fusobacterium
necrophorum from the lesion and/or blood. The differential diagnosis in
the rabbit should include other conditions that could result in multiple
abscesses such as those caused by Fusobacterium spp, Staphylococcus aureus,
Pseudomonas aeruginosa, and Pasteurella multocida. Treatment with appropriate
antibody therapy and surgical drainage of abscesses must be initiated immediately
to have any chance at being successful.
Questions:
1. Lemierre's syndrome is an eponym for what condition?
2. Name three exotoxins produced by Fusobacterium necrophorum which,
together with an endotoxin, may be responsible for host tissue necrosis.
3. What differential diagnosis should be considered in rabbits with
swelling or abscesses in or around the oropharynx, face, neck, and/or head,
especially with sepsis and signs of pulmonary dysfunction?
Answers:
1. An acute clinical condition characterized by oropharyngeal infection
with anaerobic bacteria leading to septic throbophletitis of the internal
jugular vein, with frequent pulmonary embolic abscesses.
2. leukocidins, hemolysins, and cytotoxins
3. Conditions that could result in multiple abscesses such as those
caused by Fusobacterium spp, Staphylococcus aureus, pseudomonas aeruginosa,
and Pasteurella multocida.
Epidermotropic lymphoma (Mycosis Fungoides) in an ICR mouse. Contemporary
Topics 38 (5): 47.
This is a case of epidermotropic lymphoma with systemic spread into
lymph nodes and visceral organs in a 8 month old female ICR sentinel mouse.
The mouse had progressive, generalized alopecia and lymphadenopathy for
several weeks. The skin was markedly and diffusely thickened, with multiple
serous to hemorrhagic crusts, ulcerated plaques, and raised nodules (see
pictures in article). Microscopically there was perivascular infiltration
of pleomorphic lymphoid cells in skin, lymph nodes, thymus, spleen, lungs
and liver. Most infiltrating cells were labeled with anti-CD3 (pan T cell)
antibody. Epidermotropic lymphoma (mycosis fungoides) is a form of cutaneous
T-cell lymphoma present in people and mainly in dogs, and cattle but also
cats, hamsters, rats, horses, and ferrets. It mimics dermatitis in patches
or plaques early on then progresses to nodules or tumors. Neoplastic cells
infiltrate the epidermis, dermis and SQ and may spread to peripheral lymph
nodes and visceral organs in the later stages. The cause is uncertain and
genetic, infective and environmental factors may play a role. The mechanism
may be related to bone marrow derived T-cell precursors going directly
to the skin bypassing the thymus due to a histogenesis error. In humans,
the pathognomonic histologic features include: cutaneous infiltration,
convoluted nuclei, and epidermal tropism of atypical T lymphocytes.
No questions - see photos.
Gastric perforation in WAG/Rij rats after esophagojejunostomy. Contemporary
Topics 38 (5): 50.
This study was performed to evaluate a new treatment modality for Barrett's
esophagus in an animal model using inbred male WAG/Rij rats (Harlan, CPB
Auststerliz,the Netherlands) in which jejunoesophageal reflux was experimentally
induced. This was done by surgical resection of the esophagus with the
jejunum and sealing of the stomach. All animals did well until thirty-nine
days post operative at which time they died if they were not treated. Barrett's
esophagus is a premalignant lesion of the esophagus defined as the presence
of columnar epithelium with intestinal metaplasia in the esophagus with
the cause of longstanding gastroesophogeal reflux.
The cause of death, gastric perforation and peritonitis, in these animals
after thirty-nine days was clearly evident. There was a clear yellow fluid
in the stomach of these animals without perforation. Some non-pathogenic
bacteria were isolated and the clear fluid in the stomach had a pH of 4.5
to 7.0. Macroscopic changes were not observed; however, microscopic examination
of the proximal half of the stomach revealed hyperkeratosis, hyperplasia
of the squamous epithelium, papillomas, inflammatory reaction, hemorrhage
and ulceration.
Bacterial causes were considered to be Helicobacter bilis and H. meridium
which are widespread but are subclinical. H. pylori species and Gasrospirilium
suis have ulcerogenic action on the glandular stomach; although clear stomach
content and peritonitis, if present, was sterile except for some non-pathogenic
E. coli. Lactobacillus and Bacillus may adhere to keratined epithelium
of the forestomach. Candida albicans may colonize alimentary tract of rats
treated with antibiotics. Bacteria or fungi could not be identified on
the gastric wall even with several special stains.
Gastric ulceration may be induced by several different causes. A deficient
blood supply to the gastric mucosa caused by the action of bacteria could
be ruled out due to the lack of Helicobacter pylori. Drugs were not used
and they could be ruled out. Digestive juices could lead to gastric ulceration
but the mechanism is not well understood. Trophic and glandular disturbances
could strongly lead to ulceration and eventually gastric perforation. The
loss of vagal function can cause stomach distention and death; however,
vagal stimulation may cause high gastric ulceration incidence in rats.
Immobilized rats develop stress ulcers in the glandular stomach. Ligation
of the pyloris in conjunction with a low pH may also cause ulceration in
the stomach when it is empty. Fasting of these animals was found to be
an important cause of this condition; the pathogenesis is not clear but
gastric acid was not the causal factor and withdrawal of food away from
the bypassed stomach must never be forgotten in these type of studies.
Vagotomy may lead to motor-impaired stomach that cannot empty its alkaline
content that pools between the non-glandular and glandular stomach. The
small amounts of food and high frequency of feedings prevent the formation
of non-glandular papillomas.
Questions:
1. What is Barrett's esophagus?
2. Death in this animal model with esophagojejunostomy and a sealed
stomach was caused by:
a. eschemia
b. bacteria
c. toxic agents
d. trophic and glandular disturbances
Answers:
1. A preliminary lesion of the esophagus defined as presence of columnar
epithelium with intestinal metaplasia in the esophagus.
2. d.
Hemagglutination inhibition (HAI) assay. Contemporary Topics 38 (5):
54.
A review of the HAI assay (the figures explains this very well, better
than my words will, so I would encourage you to take a look)
Purpose- to detect antibodies to viral pathogens.
How it works- some viruses contain hemagluttinins on their surface
membrane that bind red blood cells of certain particular species.
Viral Antigen (w/ hemagluttinins) incubated with serial dilutions of
serum (which would contain the antibody you are testing for).
Add red blood cells of a species that will hemaglutinnate with the
virus.
If antibodies are not present- (Negative HAI) red blood cells will
hemagglutinate- red blood cells from wavy or feathery appearance in bottom
of cell
If antibodies are present (Positive HAI) red blood cells will NOT hemagglutinate-
the antibodies in the serum bind to the viral antigen and prevent the RBC
from agglutinating, RBC form a plug or button on bottom of cell.
Alternative techniques ?ELISA, IFA, Immunohistochemistry, and Western
Blot.
Advantages- HAI Specificity is very high
Disadvantages- Sensitivity is low, not all viruses contain hemagglutins,
subjective interoperation
Questions-
If sensitivity is low and specificity is high- would HAI be a good
screening test? Why/why not.
Not a good screening test- low sensitivity would result in false negatives.
HAI makes a better confirmation test because of the specificity- low
rate of false positives.
Isolator rodent caging systems (state of the art): a critical view.
Contemporary Topics 38 (5): 9.
This article presents some of the recent developments in rodent housing.
There have been major changes in rodent housing principles, driven by the
dramatic increase in numbers of genetically engineered mice. The specialized
needs of these colonies require isolator cages to keep animals free of
pathogens. Isolator cages are used frequently, and individually ventilated
caging systems are becomming even more common.
The first isolator cage was developed by Dr. Lisbeth Kraft in thte
late 1950's. It was a filter top system, and worked well to protect immune-naive
mice from contamination with epidemic diarrhea of infant mice, a highly
infective rotavirus. The static isolator systems have problems related
to microenviormental air quality. There are significantly increased levels
of NH3, CO2, and humidity in the cages. Despite these disadvantages, static
isolators are particularly useful in the containment of hazardous material
at the cage level. Some examples include administration of biological pathogens
or radionuclides. The problems assocaiated with static isolator can be
overcome by frequent cage changes, use of good quality contact bedding,
reduction of macroenvironment relative humidity, or increase in macroenvironment
temperure.
Ventilated isolator caging systems were developed in the early 1980's.
This system dramatically improves the mircoenviornmental air quality. The
use of ventilated caging systems (VCS) may create substantial operational
savings through decreased labor and energy costs, increase the longevity
of caging components, and increase stock density. The increased ventilation
at the cage level may, however, cause chilling and dehydration of neonates
and hairless mutants. The macroenvironmental room temperature may need
to be elevated to compensate. There may also be pheremone dilution at the
increased ventilation rate, causing changes in breeding behavior or maternal
bonding. Use of these systems may cause an increased heat load and increased
noise generation in the facility. VCS are of two general types: intracage
supply/ perimeter capture and intracage supply/ intracage exhaust systems.
QUESTIONS:
1. Thoren Caging Systems, Inc produce what kind of rodent housing?
2. One situation where a static isolator caging system is preferred
over a ventilated caging system is:
3. Name two ways that microenviornmental air quality prblems can be
addressed when using a static isolator caging system.
ANSWERS:
1. Thoren Caging Systems, Inc., produce ventilated caging systems with
intracage supply/ intracage exhaust (indirect) systems.
2. In vivo administration of hazardous agent, such as biological pathogens,
hazardous chemicals, or radionuclides
3. frequent cage changes, good quality contact bedding, reduce relative
humidity in marcoenviornment, or increase temperature in macroenvironment.