Comparative Medicine
Volume 60, Number 2, April 2010
ORIGINAL RESEARCH
Zebrafish Model
Bouvrette et al. Knockdown of Bicaudal C in Zebrafish (Danio rerio) Causes
Cystic Kidneys: A Nonmammalian Model of Polycystic Kidney Diseases, pp. 96106
Domain 3 - Research, T3 - Design and conduct research, TT3.3. Animal models
Secondary Species – Zebrafish
SUMMARY: Polycystic kidney disease (PKD) is one of the leading causes of end-stage
renal disease in humans and is characterized by progressive cyst formation, renal
enlargement, and abnormal tubular development. Currently, there is no cure for PKD.
Although a number of PKD genes have been identified, their precise role in cystogenesis
remains unclear. In the jcpk mouse model of PKD, mutations in the bicaudal C gene
(Bicc1) are responsible for the cystic phenotype; however, the function of Bicc1 is
unknown.
Rodent models have played an important role in the identification of genes involved in
cystogenesis; however, determining the in vivo function of these genes is cumbersome
due to the lack of efficient means to manipulate gene expression in living animals.
Zebrafish offer an attractive alternative to rodent PKD models due to the ease of
visualizing organs and tissues in the transparent embryos and juveniles, the
conservation of genetic pathways regulating organogenesis, and the ability to rapidly
assay loss- and gain-of-function phenotypes for any gene.
In this study, the authors have established an alternative, nonmammalian zebrafish
model to study the role of Bicc1 in PKD pathogenesis.
In this study:
1. They used antisense morpholinos to evaluate loss of Bicc1 function in zebrafish.
2. The resulting morphants were examined histologically for kidney cysts and
structural abnormalities.
3. Immunostaining and fluorescent dye injection were used to evaluate pronephric
cilia and kidney morphogenesis.
4. Knockdown of zebrafish Bicc1 expression resulted in the formation of kidney
cysts; however, defects in kidney structure or pronephric cilia were not observed.
5. Expression of mouse Bicc1 rescues the cystic phenotype of the morphants.
6. They found that the function of Bicc1 in the kidney is evolutionarily conserved,
thus supporting the use of zebrafish as an alternative in vivo model to study the
role of mammalian Bicc1 in renal cyst formation.
QUESTIONS:
1. Elimination of bicc1 function in the zebrafish causes -----------------formation
a. Cyst
b. Kidney inflammation
c. Pronephric cilia
d. Kidney stones
2. Zebrafish offer an attractive alternative to rodent PKD models due to: (Select the
wrong answer)
a. The ease of visualizing organs and tissues in the transparent embryos and
juveniles
b. The conservation of genetic pathways regulating organogenesis
c. The ability to rapidly assay loss- and gain-of-function phenotypes for any gene.
d. The Zebrafish is relatively small when compared to other models
3. What is the primary goal of this study?
a. To demonstrate conservation of Bicc1 function in the kidneys of zebrafish and
mice
b. To demonstrate the gain of function phenotypes associated with Bicc1
c. To characterization of a zebrafish bicc1 splice variants
d. To demonstrate the usefulness of Zebra fish as model system
4. Many genes involved in PKD code for proteins that localize to the:
a. Primary cilia or basal body
b. Kidney epithelium
c. Medullary collecting duct cells
d. Nephron
5. In the current study,---------- distinct morpholinos that specifically targeted bicc1a
were used. They all yielded similar phenotypes, suggesting that the cystic
phenotypes are a direct result of the loss of bicc1a function.
a. 2
b. 3
c. 4
d. 5
ANSWERS:
1. A
2. D
3. A
4. A
5. A
Frog Models
Bartlett et al. Echocardiographic Assessment of Cardiac Morphology and
Function in Xenopus, pp. 107-113
Domain 3: Research; T1. Facilitate or provide research support; T2. Advise and consult
with investigators on matters related to their research; T3. Design and conduct research
Secondary Species: African clawed frog (Xenopus laevis) and western clawed frog – (X.
tropicalis)
SUMMARY: Advances using Xenopus as a model permit valuable inquiries into cardiac
development from embryo to adult. Noninvasive methods are needed to study cardiac
function longitudinally. Echocardiographic and electrocardiographic studies in Xenopus
provide information about cardiac anatomy and physiology and can readily be used for
longitudinal analyses of developmental inquiries.
The objective of this study was to evaluate the feasibility of echocardiographic studies in
Xenopus and establish normative data of adult cardiac structure and function.
Methods: Doppler and 2D echocardiograms and electrocardiograms were acquired from
adult Xenopus laevis and X. tropicalis. Frogs were exposed to either isoflurane or
tricaine to discern the effect of sedating agents on cardiac function. Cardiac dimensions,
morphology, flow velocities, and electrophysiologic intervals were measured and
evaluated by using bivariate and regression analyses. Normal cardiac dimensions
relative to body weight and species were established by echocardiography. Normal
conduction intervals were determined by electrocardiography and did not vary by body
weight or species.
Results and Conclusions: Anesthetic agent did not affect ejection fraction or flow velocity
but did alter the QRS duration and QT interval (QRS shorter for isoflurane and QT longer
for isoflurane, vs. tricaine. Body weight, species, and anesthetic agent are factors that
should be considered in experimental design and analyses.
Additional notes: Anesthesia – Immersion in 1% tricaine for 30 minutes, or isoflurane
topical application were used for anesthesia. Topical isoflurane anesthesia was achieved
by saturating the absorptive pad of an adhesive bandage with 2.5 ml of 100% isoflurane
and applying it to the dorsal surface of the frog (adapted from Cont Top Lab Anim Sci
39:39-42, 2000). This was an effective anesthetic, with induction time 22.5 +/- 15.2
minutes, and recovery time (time till able to swim at the tank surface) of 62.5 +/- 33
minutes. The prolonged recovery time for isoflurane anesthetized frogs, and transient
disruption of the skin mucous coat were considered to be factors that made use of
tricaine immersion the preferred method for Xenopus anesthesia, though differences in
conduction physiology were noted between electrocardiography data obtained using the
two anesthetic methods.
QUESTIONS
1. The heart of clawed frog species (Xenopus) has how many chambers?
a. Three
b. Four
c. Two
2. Methods for noninvasive cardiac physiology studies include:
a. Echocardiography
b. Electrocardiography
c. Angiography/coronary catheterization
d. a and b
e. all of the above
3. True or false: topical isoflurane can be an effective and safe anesthetic in aquatic
amphibians such as Xenopus species.
4. Anesthetic agents (1% tricaine immersion vs. topical isoflurane) were associated with
significant differences in what cardiac physiology parameters in Xenopus?
a. Electrophysiology (relative wave and interval lengths)
b. Ventricular ejection fraction
c. Flow velocity across the AV valve
d. b and c
e. All of the above
5. True or false: body weight and species are both factors that can be associated with
variation in cardiac dimensions and electrophysiology in anesthetized Xenopus.
ANSWERS
1. Three – left and right atria plus a single ventricle
2. d
3. True – delivered by saturating the absorbent pad of an adhesive bandage with a
measured amount of isoflurane and applying it to the frog’s dorsal surface.
4. a – tricaine anesthesia was associated with longer QRS duration and shorter QT
interval than those of isoflurane anesthetized frogs
5. False: in anesthetized Xenopus there is a significant association of cardiac
dimensions with body weight and species, but there is no significant difference in
electrophysiology (conduction physiology).
Schadich and Cole.
Pathogenicity of Aeromonas hydrophila, Klebsiella
pneumonia, and Proteus mirabilis to Brown Tree Frogs (Litoria ewingii), pp. 114117
Tertiary Species: Other amphibians
Domain 1, Task 1-3
SUMMARY: Bacterial dermatosepticemia is a fatal disease of frogs with disease
development dependent upon such factors as organism virulence, environment, diet,
stress, health and immune status of the animal. In order to determine the pathogenicity
of frog bacterial pathogens, they (frogs) are subjected either to injection of the pathogen
or immersion in a bacterial suspension (also called bath challenge). This study
assessed the pathogenicity of three bacterial isolates (A. hydrophila, K. pneumoniae and
P. mirabilis) from Brown tree frogs (Litoria ewingii) using the bath challenge. Frogs were
immersed twice at 40 minute intervals and allowed a 30 minute rest period between the
two immersions. Control animals were exposed to pond water only. Animals were
returned to their home cages following bacterial exposure and monitored for 3 weeks.
Results indicated that 2/5 frogs challenged with K. pneumoniae became fully
symptomatic for disease 7 days following exposure with final morbidity and mortality
reaching 40%. No signs of morbidity or mortality were seen with control frogs of frogs
exposed to A. hydrophila or P. mirabilis.
QUESTIONS:
1. T/F The aim of pathogenicity models is to reproduce disease in vivo by challenging
the select host with bacterial isolates.
2. Uses of pathogenicity models include:
a. Disease monitoring
b. Comparison of pathogenicity of different bacterial isolates
c. Evaluation of efficacy of prophylactic and chemotherapeutic treatments
d. A and B
e. All of the above
3. Prolonged time is required for disease development in various frog species after bath
challenge with this fungal pathogen:
a. Litoria ewingii
b. Klebsiella pneumoniae
c. Aeromonas hydrophila
d. Batrachochytrium dendrobatidis
ANSWERS:
1. T
2. E
3. D
Mouse Models
Acar-Perk et al. The t914,15) in Mouse Strain CBS/CaH-T(14;15)6Ca/J Causes a
Break in the ADAMTS12 Gene, pp. 118-122
Domain 3: Research
Tasks: T1 - facilitate or provide research support; T3 - design and conduct research
Knowledge: K2 - research methods and equipment; K3 - animal models; K4 - genetics
and nomenclature; K5 - genetic modification/engineering technology including
application of molecular biology techniques; K6 - characterization of animal models
Primary Species: Mus musculus
SUMMARY
Background: CBA/CaH-T(14;15)6Ca/J is an inbred mouse strain with a homozygous
balanced reciprocal translocation between chromosomes 14 and 15. In heterozygotes,
approximately half of the gametes produced contain defects that cause zygote death in
utero. One gene in this region that could cause these abnormalities if interrupted is
ADAMTS12 (adisintegrin and metalloproteinase with thrombospondin motifs), a gene on
chromosome 15 that is thought to be involved in collagen maturation, organogenesis,
angiogenesis, reproduction, and inflammation. This study supports the presence of
homozygous interruption in ADAMTS12 in CBA/CaH-T(14;15)6Ca/J mice.
Materials and Methods: This study used homozygous CBA/CaH-T(14;15)6Ca/J mice
and
heterozygous B6D2F1
xCBA/CaH-T(14;15)6Ca/J and C57BL/6 x CBA/CaHT(14;15)6Ca/J mice. The mice were euthanized at 25 weeks of age, and samples of
abdominal skin were rinsed with mouse embryonic fibroblast medium, minced, and
incubated at 37 deg C, 5% CO2 for 15 days to prepare fibroblast cell cultures. The
fibroblasts were synchronized and arrested in the metaphase stage. Trypsin was added
to the cultures, and the cells were centrifuged and rinsed several times before
resuspension. Fluorescent in situ hybridization (FISH) and several labeled DNA probes
were used to visualize chromosome break points. The samples were denatured, mixed
with labeled probe DNA, and mounted on slides overnight. The slides were then rinsed,
counterstained with DAPI, and examined by fluorescent microscopy. RT-PCR and
Western blot analysis were performed to test for ADAMTS12 precursor and gene
product in homozygous and heterozygous mice.
Results: In the first experiment, the following DNA probes were used: RP23-220O14
(red, chromosome 15 centromeric to break point), RP23-98B21 (yellow, chromosome 15
telomeric to break point), RP23-399K3 (green, chromosome 14 centromeric to break
point), and RP23-51F3 (blue, chromosome 14 telomeric to break point). Most
translocated heterozygote chromosomes and all of the homozygous chromosomes
followed the predicted translocation pattern, with the blue and red labels combining on
chromosome 15 and the green and yellow labels combining on chromosome 14. In the
second experiment, only homozygotes were examined, and the RP23-399K3 green
probe was replaced with one of two other green probes: RP23-406N13 (green,
chromosome 15 spanning break point) and RP23-290G19 (green, chromosome 15
telomeric to break point). The RP23-406N13 signal was split between the translocation
products, while the RP23-290G19 signal was only detected with one set of translocation
products (with the yellow signal translocated to chromosome 14). RT-PCR detected a
116-bp amplicon (presumably from the ADAMTS12 gene) in the heterozygous, but not
the homozygous, mice. Western blot analysis detected a 178-kDa precursor
from ADAMTS12 in heterozygotes but not in homozygotes.
Discussion: ADAMTS12 is synthesized as a peptide precursor that is then cleaved into
two products: one containing the metalloproteinase and disintegrin domains, and one
containing the thrombospondin domain. ADAMTS12 has been implicated to have a role
in the pathogenesis of arthritis and asthma, neither of which were seen in the young
mice (< 25 weeks old at euthanasia) used in this study. It also appears to have a role in
tumor suppression by inhibiting tumor vascularization and cell scattering. A proven
knockout mouse model of ADAMTS12 has not yet been developed but could be used to
explore the involvement of ADAMTS12 in tumorigenesis, asthma, arthritis,
organogenesis, angiogenesis, and reproduction.
QUESTIONS:
1. ADAMTS12 has been implicated in all except which of the following processes or
diseases?
a. Tumorigenesis
b. Asthma
c. Arthritis
d. Hematopoiesis
e. Angiogenesis
2. On which chromosome is the ADAMTS12 gene located?
a. 14
b. 15
c. 16
d. 17
e. 18
3. The CBA/CaH-T(14;15)6Ca/J mouse strain has which kind of translocation between
chromosomes 14 and 15?
a. Balanced reciprocal
b. Unbalanced reciprocal
c. Homologous Robertsonian
d. Non-homologous Robertsonian
e. None of the above
ANSWERS:
1. d
2. b
3. a
Christie et al. Experimental Infection of Mice with Hamster Parvovirus: Evidence
for Interspecies Transmission of Mouse Parvovirus 3, pp. 123-129
Domain 1: Management of Spontaneous and Experimentally Induced Diseases and
Conditions; T2. Control spontaneous or unintended disease or condition
Domain 3: Research; T2. Advise and consult with investigators on matters related to
their research; T3. Design and conduct research
Primary Species: Mouse
SUMMARY: Hamster parvovirus (HaPV) was isolated 2 decades ago from hamsters,
but it is not clear whether or not hamsters are the natural rodent host for HaPV, and
whether or not HaPV may actually be a slight variant of another rodent parvovirus.
HaPV infected hamsters develop clinical signs of tooth loss or discoloration, facial bone
deformities, diarrhea, stunted growth, ataxia, and death, along with gross and histologic
lesions, and similar pathogenesis is observed in neonatal and weanling hamsters
experimentally infected with rodent parvoviruses MPV1, MPV3 (a novel parvovirus
detected recently in naturally infected mice), MVM, H1, Kilham rat virus, and LuIII (a
parvovirus of unknown host origin closely related genetically to MPV). Rodent parvoviral
infections are generally subclinical in infected mice and rats, so the pathogenesis
findings in hamsters, combined with the lack of repeat HaPV disease outbreaks or HaPV
parvovirus isolations in hamster colonies, suggest that the hamster is likely an aberrant
host for HaPV, with another subclinically affected species serving as a reservoir of
HaPV. HaPV has a 98.1% nucleotide sequence homology to MPV3, so working from
the hypothesis that HaPV and MPV3 are likely variants of the same viral species for
which the mouse is the natural rodent host and the hamster is an aberrant host through
interspecies transmission, the goal of the present study was to examine the infectivity
and pathogenesis of HaPV in mice. Neonatal and weanling C3H, BALB/c, BSW and
SCID mice were inoculated with HaPV, and tissues, excretions, and sera were
harvested at 1, 2, 4, and 8 wk post-inoculation and evaluated by quantitative PCR and
serologic assays specific for HaPV. PCR detected elevated viral DNA in multiple tissues
of infected mice, most immunocompetent mice seroconverted 2 or more weeks after
inoculation, and viral DNA was detectable in feces of SCID mice 8 wk after inoculation;
no clinical signs, gross, or histologic lesions developed in any infected animals. The
results indicate HaPV can induce productive infection in mice with a pathogenesis
similar to that of MPV1 in mice, and support the plausibility of interspecies transmission
from mouse to hamster hypothesized for MPV3–HaPV. Interspecies transmission of
parvovirus rarely occurs, but the evolution of canine parvovirus from feline parvovirus
provides a paradigm for the hypothesis that HaPV originally arose after interspecies
transmission of MPV3 from mice to hamsters. From an operational standpoint, the
results of this study provide additional justification for the common practice of separate
housing for different rodent species in laboratory animal facilities.
QUESTIONS:
1. To which rodent parvovirus does hamster parvovirus (HaPV) bear the greatest
genetic similarity?
a. MPV1, mouse parvovirus 1
b. MPV3, mouse parvovirus 3
c. MVM, minute virus of mice
d. H-1PV, parvovirus H1
e. Kilham rat virus
2. Which of the following statements is not supported by the results of the authors’
study of infectivity and pathogenesis of hamster parvovirus (HaPV) in mice?
a. HaPV can induce productive infection in mice with a pathogenesis similar to that
of MPV1 in mice
b. Interspecies transmission of MPV3–HaPV from mouse to hamster is plausible
c. Pathogenesis findings in hamsters suggest that the hamster is likely an aberrant
natural host for HaPV
d. The lack of repeat HaPV disease outbreaks or HaPV parvovirus isolations in
hamster colonies suggest that the hamster is likely an aberrant host for HaPV
e. This study provides additional justification for the common practice of separate
housing for different rodent species in laboratory animal facilities
ANSWERS:
1. b. MPV3, mouse parvovirus 3
2. c. Pathogenesis findings in hamsters suggest that the hamster is likely an aberrant
host for HaPV
Guinea Pig Model
Hankenson et al. Guinea Pig Adenovirus Infection Doges Not Inhibit Cochlear
Transfection with Human Adenoviral Vectors in a Model Hearing Loss, pp. 130-135
Task 3 - Provide Research Support, Information, and Services; K1 - Biomethodology
Secondary Species: Guinea pig
SUMMARY: This study was used to determine whether natural guinea pig Adenoviral
infection affected the ability of human adenoviral vectors (hAV serotype 5) to transfect
inner ear cells in adult male pigmented guinea pigs. Animals were deafened chemically
(n=2), received an hAV vector carrying the gene for green fluorescent protein (surgically
without prior deafening, or were deafened chemically with subsequent surgical
inoculation of hAV-GFP.
Evaluation of whole mounts of the ears (chochleas), showed that human Adenoviral
vectors readily transfected the supporting cells of ears in which hair cells had been
destroyed by chemical exposure, similar to what has been described for animals known
or presumed to be free of guinea pig Adenoviral infection.
QUESTIONS:
1. Why is the guinea pig the typical animal model for studying inner ear biology?
2. How was chemical deafening achieved in this study?
3. What reflex was used to verify deafening in the guinea pigs?
ANSWERS:
1. Easy cochlear access
2. Chemical deafening was achieved via a SQ dose of Kanmycin, followed 2-4 hours
later by ethacrynic acid injected in to the jugular vein.
3. Preyer reflex
Swine Models
Cirera et al. Expression Profiles of miRNA-122 and Its Target CAT1 in Minipigs
(Sus scrofa) Fed a High-Cholesterol Diet, pp. 136-141
Task 3, K2; Task 9, K1 & K2
Primary Species: Sus Scrofa
SUMMARY: This was a study utilizing the Gottingen minipig to look at high fat intake,
obesity, and potential biomarkers for the disease. Several genes have been identified
as playing a role in obesity and microRNA (miRNA) is also thought to play a role as
well. MicroRNAs regulate gene expression at the posttranscriptional level, and some
miRNAs have been associated with lipid metabolism. They are also known to be
enhancers of viral replication, tumor suppressors, and biomarkers of drug-induced liver
injury. The relationship between miRNAs and CAT1 is one at the time of RNA
degradation where miRNA regulates CAT1 through posttranslational regulation. CAT1 is
an amino acid transporter and has several important metabolic functions including cell
survival under stressful conditions and liver development.
The study found that in pigs fed a high cholesterol diet when compared to pigs fed a
standard diet, the pigs fed a high cholesterol diet had lower levels of miRNA, lower
levels of triglycerides, increased weight gain, and increased cholesterol levels. The
decreased expression of miRNA in these pigs confirmed the implication of miRNA in
obesity. The gene expression levels of CAT1 were not different between groups.
QUESTIONS:
1. Define miRNA and its significance. How does it change with obesity?
2. What is the estrus length and gestation length of a pig? Do these differ between
minipigs and regular farm pigs?
3. This article mentions the Ossabaw pig. What is the significance of an Ossabaw pig
and why would it be mentioned in this article?
ANSWERS:
1. MicroRNA regulates gene expression and has been known to enhance viral
replication, suppress certain tumors, and be a biomarker of liver injury. Its
level decreases with obesity.
2. Estrus-21d. Gestation-114d. (3mo, 3w, 3d) No difference between minipigs and
farm pigs.
3. The Ossabaw minipig is known for its ability to accrue and store more fat than other
pigs fed the same diet. Therefore, they are often utilized on studies of Type II
diabetes and metabolic disease.
Liu et al. Light Microscopic, Electron Microscopic, and Immunohistochemical
Comparison of Bama Minipigs (Sus scrofa domestica) and Human Skin, pp. 142148
Domain 3: Research)
Primary Species: Bama minipig (Sus scrofa domestica)
SUMMARY: There is a need for animal models for human skin studies, as human skin is
often not readily available. Rodent skin has been used, but there are major differences,
such as rodents having a very thin epidermal layer, and healing occurs primarily by
contraction, which makes the use of rodent species problematic. In many respects
nonhuman primate skin is more similar to human skin, but use of this animal in research
can be very restrictive. Even though swine skin has been found to be very similar to
that of a human, the rapid growth rate and complex genetic background of the domestic
pig can make them unsuitable research models. However, the Bama miniature pig has
a more manageable size and its genetic background is well defined. This study
compared characteristics of Bama miniature pigs to human skin to evaluate this species
as an appropriate animal model for human studies.
23 male and 23 female Bama pigs aged 1 to 6 months were used in this study. Human
skin was obtained with consent from patients having undergone plastic surgery. Light
microscopy and TEM were used to evaluate the histologic makeup of the skin samples.
Similarities were found between the two species. Both Bama and human skin were
comprised of the 5 strata and both the dermis and epidermis had structural similarities.
Both species also shared compositional characteristics of the fat, collagen and elastic
fibers of the dermal layer. The thickness of the horny layer, the layer responsible for
drug penetrability, was very similar. Pigs, along with primate species including humans
share specialized features of skin, such as the highly vascular arrangement of the
superficial layer, mast cell granules, basal cell heterogeneity, and the serrated
epidermal-dermal junctions. There were, though, species specific differences, such as
skin thickness (exclusive of the horny layer) which was shown to be age dependent in
Bama skin. Pigs less than 1 month old had a thinner dermal layer than humans, in pigs
over 6 months old, the epidermis and dermis were thicker than that of humans. There
were also fewer pigment cells in the minipig skin and Bama pig skin has only apocrine
sweat glands. Although the interspecies variations found in the microscopic and
immunohistochemical comparison of the skin warrant further studies to determine the
ramifications of these differences, this study concluded that the Bama minipig is a
suitable animal model for studies involving human skin.
QUESTIONS:
1. What is the type of sweat gland that cannot function to adjust body temperature?
a. Apocrine
b. Eccrine
2. Rodent skin heals primarily by
a. Reepithelization
b. Contraction
3. The stain used for mast cells is
a. Silver stain
b. Fontana
c. Orcein
d. Toluidine blue
4. The horny layer of the skin is the main barrier to drug penetration. True or False
5. What is the predominant collagen of the dermis?
a. Collagen Type I
b. Collagen Type II
c. Collagen Type III
ANSWERS:
1. a
2. b
3. d
4. True
5. a
Dolphin Model
Venn-Watson et al. Hypocitraturia in Common Bottlenose Dolphins (Tursiops
truncates): Assessing a Potential Risk Factor for Urate Nephrolithiasis, pp. 149153
Domain 1: Management of Spontaneous and Experimentally Induced Diseases and
Conditions; Task 3: Diagnose disease or condition as appropriate
Tertiary species: Bottlenose Dolphin (Tursiops truncatus)
SUMMARY: Numerous cases of urate nephrolithiasis have been reported in captive
bottle nosed dolphins, but not in wild populations. Risk factors for humans with this type
of stone include low urinary pH and hypocitraturia. Urine samples from captive (free
catch sample) and wild dolphins (catheterized sample) were compared. A significant
difference in citrate:creatnine was seen between the two populations: 2 +/- 1 in the
captive, 150 +/- 28 in the wild. Uric acid levels, creatnine, and pH were not significantly
different between captive and wild samples. Urine samples were compared between
captive fasted and captive fed animals with no significant difference seen in the citrate
level (although fasted animals had a higher creatnine level and lower uric acid level).
Hypocitraturia is a risk factor in humans for stone formation and may be associated with
a wide range of kidney stone diseases including those associated with renal tubular
acidosis, renal hypercalciuria, and idiopathic nephrolitiasis. Hypocitraturia may be a
direct cause of nephrolithiasis or an indicator of another cause of nephrolithiasis.
Dolphins with greater than 20 nephroliths are significantly more likely to have high serum
creatnine, high blood urea nitrogen, low glomerular filtration rate and low urinary pH
compared with dolphins with no evidence of nephroliths. Possible reasons for low citrate
include: increased reabsorption of citrate during chronic metabolic acidosis (possibly
related to feeding behaviors in captivity), very high protein diet, lack of salt water
ingestion during feeding, vitamin supplementation, diabetes-like metabolism (metabolic
syndrome). Possible future studies include altering the diet, supplementation of
potassium citrate, urinary calcium, potassium, and phosphorous levels as well as
microscopic analysis.
QUESTIONS:
1. What appears to be a common pathophysiologic finding in the development of
urinary stones in humans and dolphins?
2. In humans, what functions does urinary citrate serve?
ANSWERS:
1. Insulin resistance (predisposes to uric acid calculi in humans and ammonium urate
calculi in dolphins).
2. Alkalinizer and chelator of calcium ions, both of which decrease the risk of stone
formation.
Nonhuman Primate Model
Ely et al. Use of Biomarkers in Collagen Types I and III Fibrosis Metabolism to
Detect Cardiovascular and Renal Diseases in Chimpanzees (Pan troglodytes), pp.
154-158
Tertiary Species – Other Nonhuman Primates
SUMMARY: The leading cause of death in captive chimpanzees is cardiovascular
disease (CVD) seen most commonly as sudden death. The only significant lesion noted
on necropsy of these animals is myocardial fibrosis. The hypothesis underlying the
present study was chimpanzees with incipient CVD have increased collagenous tissue in
the heart that can be detected clinically antemortem by use of fibrogenesis biomarkers
developed for use in humans.
To test this hypothesis, 5 biomarkers used extensively in humans were investigated:
1) Matrix metalloproteinase 1(MMP1); involved in structural remodeling of the left
ventricle (LV) during congestive heart failure by degrading extracellular matrix
proteins.
2) Tissue inhibitor of metalloproteinase 1 (TIMP1): blocks MMP1.
3) Procollagen carboxyl-terminal telopeptide (PINP): A fragment cleaved from
procollagen I and a marker of collagen I synthesis.
4) Initial carboxyl-terminal telopeptide (ICTP): first degradation product of collagen type
I by MMP1.
5) Procollagen III amino-terminal propeptide (PIIINP): cleaved from procollagen III, is a
marker of collagen III turnover.
These 5 fibrogenesis markers were assayed in this pilot study of 10 chimpanzees with
CVD and 10 control chimpanzees, to determine whether chimpanzees with CVD
exhibited increased serum concentrations of fibrogenesis biomarkers when compared
with heart-healthy controls.
The biomarker MMP1 did not cross-react in chimpanzee sera and was not studied
further. Two biomarkers (TIMP1 and PINP) showed no significant association with CVD
in chimpanzees. The biomarkers ICTP and PIIINP were significantly increased in cases
of CVD with concurrent renal disease. Both biomarkers showed a significant trend to
increase with disease severity. The investigators concluded that ICTP and PIIINP
warrant further study for antemortem detection of renal and myocardial fibrosis in
chimpanzees.
QUESTIONS:
1. __________ is the predominant cause of morbidity and mortality in captive
chimpanzees.
a. Renal disease
b. Cardiovascular disease
c. Renal amyloidosis
d. Hepatic disease
2. The current understanding of chimpanzee CVD reviewed in this article appears to
involve clinical progression from left ventricular hypertrophy to dilated
cardiomyopathy, initiated by certain disease processes including:
a. Systemic hypertension
b. Amyloidosis
c. Obesity
d. Hepatic failure
3. Which biomarker did not cross react in chimpanzee sera and was not studied
further?
a. ICTP
b. PIIINP
c. TIMP1
d. MMP1
e. PIINP
4. Which 2 commonly used biomarkers of fibrogenesis in this article where found to
identify chimpanzee CVD cases?
a. ICTP
b. PIIINP
c. TIMP1
d. MMP1
e. PIINP
ANSWERS:
1. b - Cardiovascular disease (CVD), including cardiomyopathy, systemic hypertension,
cardiac arrhythmias, congestive heart failure, premature ventricular complexes, and
cardiac arrest.
2. a
3. d
4. a & b