The effects of housing enrichment on cardiovascular parameters in
spontaneously hypertensive rats. Contemporary Topics 39 (1): 9.
This study looked at the effect of various housing situations on multiple
cardiovascular parameters in SHR (spontaneously hypertensive rats). Adult
male SHR rats were implanted with radiotelemetric transmitters with catheters
inserted in the femoral artery. After recovery from surgery, baseline values
were recorded. These included mean systolic and diastolic blood pressure,
mean heart rate and total activity.
During the first period, individually housed males were compared with
pair-housed males. In the second period, each cage was enriched by adding
a large piece of plastic drainpipe and several golf balls. In addition,
all the animals were placed together daily for 2 hours at the beginning
of the dark cycle. During the last period, rats previously individually
housed were paired with another rat. Likewise, pair-housed rats were separated
to single housing cages. Light cycle values were compared to dark cycle
values.
Results confirmed earlier reports that show SHR rats have marked circadian
rhythms in blood pressure, heart rate and activity. Pair-housed rats were
more active and had higher systolic blood pressure when compared to individually
housed rats. This was true with and without enrichment (in the form of
manipulata or social enrichment). Finally, animals moved from double to
single housing had significantly higher blood pressures and heart rates
than rats changed from single to double housing.
Differences in cardiovascular parameters occuring at night between
the 2 groups were linked to differences in activity. However, this correlation
did not exist during the day. Therefore, the addition of enrichment which
resulted in increased blood pressure may indicate that this change was
viewed as a stressor. Further work needs to be done in various rat models
to eludicate which 'enrichments' result in decreased stress in the animals,
and which actually stimulate a neurogenic stress response.
Questions:
1. What is the SHR rat?
2. Name 2 methods for measuring blood pressure.
3. T/F SHR rats have defined circadian rhythms detectable in cardiovascular
parameters.
4. T/F Placement of enrichment devices decreases the heart rate and
blood pressure in SHR rats.
Answers:
1. Spontaneously hypertensive rat
2. Tail-cuff method (indirect) and arterial cannulation (direct)
3. T
4. F This did not always result in decreases in cardiovascular parameters.
Environmental Enrichment for rhesus macaques: a cost-effective exercise
cage. Contemporary Topics 39 (1): 14.
This article discusses a novel method of modifying pre-existing, but
outdated caging to serve as a portable excercise cage for environmental
enrichment in non-human primates (must see picture of caging in article
to appreciate). The newly modified caging serves to curb negative behavioral
stereotypes in singly housed macaques as well as providing substantial
cost savings. The authors also noted that use of these cages led to decreased
self-directed biting, improved food consumption and and increased visual
attentiveness by other animals.
Questions:
Q1. What are the recommended caging requirements for rhesus macaques
up to 10 kg ( according to the "Guide")?
Q2. What are the recommended requirements for housing two or more animals
in the same cage?
Q3. True or False
Type 304 stainless steel is recommended for nonhuman primate caging
composed of stainless steel.
Answers:
A1. 32 " high, 4.3 ft sq
A2. The cage floor must be the sum of the space required for both animals
and the cage height must be the sum of space required for both animals
and the cage height must meet the requirements for the largest animal (exception:
mothers with infants less than 6 months
A3. True
Stress produced by gavage administration in the rat. Contemporary
Topics 39 (1): 17.
The relationship between gavage administration of various vehicles
and induction of the stress response was studied in rats. Increased plasma
corticosterone levels were used as the indication of the stress response.
Additionally, elicitation of clinical signs of distress and aspiration
leading to airway/pulmonary changes were assessed. The following vehicles,
commonly used in toxicology studies, were assessed: water, corn oil, 1%
methylcellulose/0.2% Tween 80.
After a quarantine and acclimation period to the dosing regime, rats
were randomized into vehicle groups at various dosages. An hour after dosing
rats, blood samples were collected (for corticosterone levels), then 4
hours after dosing rats, the rats were euthanized by carbon dioxide asphyxiation.
Rats were necropsied with the respiratory tract being examined for evidence
of aspiration. Lungs were weighed and removed.
Gavage administation of the vehicles at dose levels of greater or equal
to 20 ml/kg resulted in clinical signs in rats. Gavage administration of
corn oil at greater or equal to 20 mg/kg induced a stress response in a
volume-dependent fashion, resulting in elevated plasma corticosterone levels.
This response was not seen with water nor 1% methylcellulose / 0.2% Tween
80; however, rats given these agents had evidence of aspiration. The response
due to corn oil was also seen after gavage administration of sesame, soybean,
and peanut oils. Consequently, gavage dosing of lipid vehicles induces
activation of the stress response in a volume-dependent fashion.
QUESTIONS
Q1: How is dose volume determined for administration in gavage studies?
Q2: Which agent induced a stress response in a volume-dependent fashion?
Q3: What is the dose volume limit for gavage administration in the
rat (according to this study)?
ANSWERS
A1: solubility of test compound in vehicle
dose level to be administered
stability and homogeneity of dosage formulation
concentration of test compound in vehicle
A2: corn oil
A2: 10 mg/kg
A novel vented microisolation container for caging animals: microenvironmental
comfort in a closed-system filter cage. Contemporary Topics 39 (1): 22.
This group designed a closed-system cage with filtered vent ports.
The placement of the ports was designed to provide continuous airflow in
an occupied cage. The metabolic heat loads of mice provided the driving
force for air flow. Upward warm air currents escaped through the top exhaust
port, while cool room air entered through the lower intake port. Computational
Fluid Dynamics (CFD) and smoke visualization helped design and document
a one - pass air circulation in this system. In addition, Hot - film anemometry
and smoke test techniques demonstrated adequate ventilation in an occupied
cage.
Results: In a room with 0 air changes per hour (ACH)
Cage occupied by 1 mouse: 6 ACH
Cage occupied by 5 mice: 12 ACH; after 1 week the avrg. cage temp
was 0.5C, relative humidity was 34%, and the ammonia concentration
was 3ppm higher than the room.
Question:
What is CFD?
Answer:
CFD is the science of determining a numerical solution to the governing
equations of fluid flow whilst advancing the solution through space or
time to obtain a numerical description of the complete flow field of interest.
A novel approach for assessing the quality and effectiveness of IACUC
oversight in investigator compliance. Contemporary Topics 39 (1): 28.
In order to measure the effectiveness of IACUC oversight and evaluation
of animal care and use, the author's IACUC retained a management consultant
group to design and conduct a survey that could be used to determine how
the IACUC could improve the process of aiding researcher compliance with
regulation and accreditation standards.
Step 1: In the first stage of the project, the management consultant
group conducted confidential interviews with IACUC members and 25 of the
facility's principal investigators. Following the interviews, the consultant
met with selected IACUC members to review findings which were subsequently
used to develop a written survey questionnaire for the second stage of
the project.
Step 2: The written survey contained 22 close-ended multiple-choice
questions, 5 open-ended questions and appropriate demographic items. Close-ended
questions were expressed in a "Strongly agree" to "Strongly disagree" response
continuum with a "No opinion" option. Open-ended questions allowed the
respondents to express their own opinions. A draft of the written questionnaire
was submitted to the IACUC for review and approval prior to distribution.
The survey was distributed to the animal-using population including technical
staff, vice-presidents, directors, etc. Survey responses were submitted
directly to the consultant group in order to maintain confidentiality.
Step 3: Survey results were presented to the IACUC in formal briefing
sessions and in a comprehensive Summary Report. Response to the written
survey was considered good (34%). Recommendations were made based on the
results of both interviews and the written survey.
In an attempt to improve overall IACUC effectiveness with respect to
investigator compliance, the IACUC instituted a plan of action that prioritized
survey findings. Follow-up surveys will be used to measure the plan's success.
The survey was considered an excellent way to assess the quality and effectiveness
of IACUC - investigator interactions by determining the level of researcher
satisfaction.
Questions:
1.) What approach did the facility's IACUC use for assessing the quality
and effectiveness of IACUC oversight in investigator compliance?
2.) How was the content of the written survey gathered?
Answers:
1.) A management consultant group was retained to objectively design
and conduct a confidential survey.
2.) The survey questions reflected information that was gathered during
the individual interviews.
Therapeutic efficacy of oral lactobacillus preparation for antibiotic-associated
enteritis in guinea pigs. Contemporary Topics 39 (1): 32.
Anecdotal evidence exists for the treatment of antibiotic associated
enteropathy for mice, hamsters, guinea pigs, and rabbits. Frequently Clostridium
difficile is implicated in most rodent species (C. spiriforme is the causative
bacterium in rabbits). This phenomenon in the hamster is used as model
for pseudomembranous colitis in people. The rational for using lactobacillus
preparations to limit disease in affected animals is: the good bacteria
will compete with potential pathogens for colonization sites as well as
produce lactic acid which is thought to stimulate GI immune function. This
study aim to assess the ability of a single dose of clindamycin to induce
enteritis in CAMM/Hartley guinea pigs and to evaluate a commercially available
lactobacillus formulation (Probiocin) for it^Òs ability to reduce
or eliminate the clinical effects of enteritis.
Results: Guinea pigs receiving only Probiocin via gavage BID remained
healthy and active. Guinea pigs receiving the antibiotic only or antibiotic
with Probiocin treatment developed large bowel edema and congestion, with
neutrophillic infiltration of the small and large bowel. No Clostridal
enterotoxin type A was detected at any time.
Conclusion: Probiocin was ineffective at preventing anorexia, weight
loss, as well as decreased food and water consumption in guinea pigs receiving
a single injection of clindamycin. They offer many hypothetical reasons
for the failure of the treatment.
Questions:
1. What organism is commonly implicated in antibiotic associated enteritits
of hamsters, mice and guinea pigs? Rabbits?
2. How does this organism cause morbidity in animals?
3. T/F Oral administration of lactic acid products to guinea pigs have
proven to be very effective at limited the clinical course of enteric disease.
4. Which antibiotic is highly associated with enteric disease in guinea
pigs?
Answers:
1. Clostridium difficile, rabbits get C. spiriforme
2. Production of Type A enterotoxin
3. False.
4. clindamycin
Outbreak of Pasteurella pneumotropica in a closed colony of STOCK-Cd28tm1Mak
mice. Contemporary Topics 39 (1): 39.
This report of an outbreak of Pasteurella pneumotropica in a group
of mice homozygous for a Cd28 gene mutation discusses both evidence for
an immunologic basis for susceptibility to this agent, and information
about the mouse strain itself. These mice are selectively immunodeficient
when homozogous for Cd28 -/-. Nude mice have been shown elsewhere to have
an increased incidence to P. pneumotropica, and in this case 20% of homozygous
pups (two to three weeks of age) showed periorbital abscesses while only
one of the heterozygotes and none of the wild type littermates showed disease.
This strain of mouse shows immunodeficiency toward some agents and
normal response to others, thus it is termed "selectively immunodeficient".
Interestingly when the homozygote is crossed with NOD mice for which Cd28/B7
interaction is important in the spontaneous autoimmune diabetes in NOD
mice, there is more rapid development of diabetes rather than the expected
resistance expected in Cd28 negative mice.
Pasteurella pneumotropica can be expected to show the following pathologic
changes: conjunctivitis, dacryoadenitis, and panopthalmitis, plus urogenital
and subcutaneous infections. There are several variants which can be distinguished
through culture media alterations, but this is difficult due to weak and
variable phenotypic reactions. PCR of the 16S sequence is currently only
available for three types, but is an easier and more definitive method
for typing. The organisms in this outbreak showed strong (99.5%) homology
to biotype Heyl.
Virulence of the organism appears low since cage mates that were not
Cd28 -/- , except for one heterozygote, did not develop signs.
Questions:
1. List three pathologic changes in Pasteurella pneumotropica infection.
2. What is meant by -/- in the name of these mice?
3. Culture is the best method to distinguish variants of P. pneumotropica.
T or F
4. What trait is found in NOD mice?
Answers:
1. conjuctivitis, dacryoadenitis, panopthalmitis, uorgenital infections,
subcutaneous infections
2. the animal are missing both alleles of the gene , in this case Cd28
gene
3. False, PCR is a more definitive and easier test
4. Spontaneous autoimmune (Type 1) diabetes mellitus
Reverse transcriptase polymerase chain reaction (RT-PCR). Contemporary
Topics 39 (1): 42.
This is a technology update illustrating RT-PCR. RT-PCR is like PCR
except that it amplifies small pieces of RNA, not DNA. This article illustrates
the RNA template, the priming event, the first strand synthesis of cDNA,
the removal of the original RNA template and finally the PCR reaction.
Questions:
1) What stain is used to visualize DNA on a gel?
2) What are alternative techniques for RT-PCR?
3) What are the advantages of RT-PCR?
4) What are the disadvantages of RT-PCR?
Answers:
1) Ethidium bromide
2) Northern blot analysis, RNAse protection assay
3) High sensitivity, very specific, can be completed fairly rapidly
(1-2 working days)
4) Similar to those of PCR, it detects mRNA and not protein