Spontaneous Ophthalmic Lesions in Young Swiss Mice. Laboratory Animal Science 49(3), 232.
Abstract: Object: Identify, qualitatively and quantitatively, spontaneous ocular lesions that need to be differentiated from lesions induced by protocol design.
Methods: Conventional husbandry, meeting AAALAC International criteria; Animals were exsanguinated under ether anesthesia for removal and fixation of both eyes.
Defects categorized regionally as; eyelids, eyeball, cornea, iris, lens, vitreous and fundus.
Lesions with greater than 5% incidence were limited to the:
Lens (anterior cortical opacity; posterior capsular opacity, nuclear opacity and anterior cortical line suture opacity).
Lesions with less than a 5% incidence included:
Eyelids (incomplete palpebral fissure):
Eyeball (micropthalmia; exophthalmia; hemorrhage and scleral mass):
Cornea (opacity with and without mineralization; neovascularization)
Iris: (coloboma; persistent pupillary membranes; pupil shape distortion; anterior/posterior synechia; miosis):
Lens: (posterior rupture; suture line opacity [complete; nuclear; posterior-cortical and subcapsular-cortical]; opacity that was anterior, equatorial, posterior or complete and involved variously the capsular, cortical and subcapsular spaces)
Vitreous: (hemorrhage; floating bodies; central hyaloid arterial remnant):
Fundus: (Coloboma; retinal fold; retinal atrophy; chorioretinal atrophy; chorodial hemorrhage; retinal vasculature pattern abnormalities)
- Eyelid and globe lesions were always unilateral with no sex predilection
- Lesions of the cornea were generally unilateral with no sex predilection.
- Of the iris lesions, only shape distortion was always unilateral with no sex predilection.
- Lens opacity is terminology used by these authors to describe an increased optical density (loss of transparency) of the lens, either along the suture lines or elsewhere in the lens. In most cases, the density increase was either very focal and small or diffuse and not opaque, allowing for fundic examination. Exceptions to this generalization were the cases of persistent hyaloid vessel remnants where opaque plaques were often formed and the few cases of complete (cataract) lens opacification.
- None of the vitreous lesions had sex predilection; were generally unilateral and did not prevent fundic examination.
- Fundic lesions were generally unilateral, and had no sex predilection
Questions: 1. A coloboma is ______________________________________________________________________
2. Lenticular sutures are ________________________________________________________________.
3. A synechia is or refers to ______________________________________________________________.
4. Epithelium is found on the anterior and posterior surface of the lens? T/F.
Answers: 1. A coloboma is a defect in or absence of some ocular structure. It is usually the result of malclosure of the fetal ocular cleft but may result from disease or trauma, including surgical procedures.
2. Suture lines of the lens are convergent points of the lens fibers. They form an upright "Y" on the anterior surface and an inverted "Y" on the posterior surface.
3. A synechia is an ocular adhesions, particularly used in reference to adhesion of the iris to the cornea or lens.
4. False. Very early in embryonic life, the posterior epithelium looses its nuclei and become primordial for the lens fibers.

Neuroendocrine (ECL cell) differentiation of spontaneous gastric carcinomas of cotton rats (Sigmodon hispidus). Laboratory Animal Science 49(3), 241.
Abstract: The authors of this paper found that the female cotton rats in one of their labs spontaneously developed adenocarcinomas in the corpus mucosa of their stomachs. They designed this study to examine the adenocarcinoma with regard to neruroendocrine diffentaion of its neoplastic cells. The cause of ECl carcinoids in rats is know to be hypergastrinemia. Blood gastrin and gastric mucosal pH were measured. Stomachs from six female cotton rats at 6 and 8 months were studied. They were examined for pathogens by micro biologic testing, direct microscopy, and serologic testing. They were also examined histologically. Fifteen other animals were euthanized for determination of blood gastrin values and gastric mucosal pH. The results showed that there were 2 normal animals, 2 with thick oxyntic mucosa, and 2 with thick mucosa and tumors. The oxyntic mucosal pH levels were significantly higher in the animals with thick mucosa with and with out tumors than the animals with normal gastric mucosa. The serum gastrin concentration was also significantly higher in the animals with pathology. The histologic examination revealed ECL cells were markedly hyperplastic in all rats with thick mucosa nd the ECL cells were found in the neoplastic parenchyma. The results inferred that the rats with the thick oxyntic mucosa may have had high gastrin concentration in the blood. This means they had reduced gastric acidity. The cause of the gastropathy is unknown.
Questions: Question:
1. What is the scientific name for the cotton rat?
2. What other African rodent also develops ECL-omas ( genus species)?
3. T/F Gastrin may play a major role in ECL hyperplasia ?
Answers: Answer:
1. Sigmodon hispidus
2. Mastomys natalensis
3. True

Effect of Respiratory Tract Disease on Pharmacokinetics of Tilmicosin in Rats. Laboratory Animal Science 49(3), 248.
Abstract: The aim of the paper was to determine the effect of chronic respiratory tract disease on tilmicosin pharmacokinetics by comparing its tissue distribution between healthy rats and rats infected with Mycoplasma pulmonis. Tilmicosin, a macrolide, is effective against Pasteurella, Mycoplasma, and Actinobacillus. This group of antibiotic has good tissue penetration and reaches higher concentrations in the lungs than in serum. However, the pharmacokinetics of this and other drugs can be dramatically altered during infections and tissue inflammation.
72 SPF LEW/SsNHsd rats were randomly assigned to two equal groups. One group was inoculated with M. pulmonis and the other received sterile broth. Day 31 post inoculation, all rats were injected with SQ dose of tilmicosin. Six rats per group were euthanized at 0 hour (before treatment), 1,3,7,24,72 hours after tilmicosin administration.
PH was measured by use of a portable pH meter. Quantitative analysis of tilmicosin concentration in serum and lung was done using high-pressure liquid chromatography (HPLC) with ultraviolet spectroscopy.
Although clinical signs of infection in rats (treatment and control) were not seen prior to or at the time of euthanasia, rats inoculated with M. pulmonis had gross pathologic changes in the lungs consistent with murine respiratory mycoplasmosis. These included scattered lesions, edema, atelectasis, and consolidation. Rats inoculated with sterile broth did not exhibit lung pathology.
Rats infected with M. pulmonis had significantly higher concentrations of tilmicosin in the lungs than did non-infected rats. There was no difference in serum concentration of tilmicosin between infected and nonfected rats. These findings suggest that infection/inflammation improves tissue penetration of tilmicosin.
Questions: Questions
1. Tilmicosin belongs to which drug class?
a. Sulfonamide
b. Cephalosporin
c. Macrolide
d. Tetracycline
e. Lincosamides
2. What is the proposed site of tilmicosin action?
3. Name at least 3 preparations belonging to the macrolide class of drugs.
4. Are macrolides bacteriostatic or bactericidal?
Answers: Answers
Tilmicosin belongs to the macrolide drug class (C).

It is hypothesized that the tilmicosin accumulates within pneumocytes or
binds to membranes and/or organelles.

Erythromycin, Tylosin, Tilmicosin, Azithromycin

Macrolides are bacteriostatic.

Characterization of the interaction of E. coli heat-stable enterotoxin (STa) with its intestinal putative receptor in various age groups of mice, using flow cytomoetry and binding assays. Laboratory Animal Science 49(3), 254.
Abstract: Enterotoxigenic Escherichia coli (ETEC) is a major cause of death for human infants and young animals. ETEC virulence factors that enable strains to cause disease include specific surface fimbriae that mediate adherence to intestinal epithelial cells, and enterotoxins that stimulate intestinal secretion. Three ETEC enterotoxins have been identified: heat-labile (LT) and two types of heat-stable (STa and STb). Heat-stable toxin-mediated diarrhea is more common and severe.
STa is a cysteine-rich, poorly immunogenic peptide that attaches to an extracellular portion of brush border guanylyl cyclase. This stimulates an increase in intracellular cGMP resulting in and intraluminal accumulation of fluids and electrolytes. The STa receptor is reported to be similar to atrial and brain natriuretic peptide receptors. In rats, pigs, and humans, an increase in STa receptor density coincided with an increased susceptibility to STa-induced disease. It is unclear if decreasing susceptibility to disease is a result of decreased receptor numbers or decreased sensitivity of receptors.
In this study, enterocyte suspensions were made from four age groups of Swiss Webster mice: 2 day old (2d), 1 week old (1w), 2 week old (2w), and 2 month old (2m). The cells were assayed with indirect immunofluorescence, flow cytometry, and 125I-STa binding. Indirect immunofluorescence showed that the most intense staining for STa occurred at the brush border and was inversely related to age. Flow cytometry showed in a more quantitative fashion that STa binding is inversely related to age. The specific binding of 125I-STa suggested an increased number of receptors in the younger mice, and the stoichiometry of 125I-STa supported both increased receptor density and increased receptor affinity (increased binding) in the 2d old mice versus the older mice. The binding assay also supported the presence of only one class of STa receptors in these mice.
Questions: Questions:
1) What are the virulence factors that enable ETEC strains to cause disease?
2) Name the known ETEC enterotoxins.
3) T or F STa enterotoxin produces osmotic diarrhea.
4) This experiment suggests what two factors produce increased susceptibility to STa-mediated diarrhea in younger vs. older mice?
Answers: Answers:
1) specific surface fimbriae on the E coli and enterotoxins
2) LT, STa, STb
3) False. STa enterotoxin produces secretory diarrhea.
4) increased STa receptor density within the brush border and increased affinity of the STa receptor for STa

Radiographic, histologic, and cytologic lesions associated with mutations in the fitness1^4226SB locus of mice. Laboratory Animal Science 49(3), 260.
Abstract: *(Characters bracketed with caret symbols ^...^ in this plain-text printout are actually superscripts)

SUMMARY: N-ethyl-N-nitrosourea (ENU) was used to cause mutations in mouse Chromosome 7, close to the region which carries a chinchilla coat allele. The ENU was given to albino male BALB/cR1 mice, and these mice were mated to (C57BL/10R1 x C3Hf/R1) F1 female mice. G1 female mice were crossed to mice heterozygous for a radiation-induced deletion in the region encompassing the chinchilla allele, so that albino G2 animals could be identified for study of the new ENU-induced juvenile-lethal "fitness" (fit1) mutation. Affected animals exhibited runting and nervousness. Of five different such alleles produced, one of moderate severity (fit1^4226SB^) was selected; mutants hemizygous for this allele were further characterized. Evaluations performed were: radiography of anesthetized animals, serum biochemistry, gross and micropathologic examination, and cytology and hematology of femoral bone marrow. Siblings with chinchilla coats appeared unaffected and were used as controls throughout this study.
Radiographic observations: scoliosis, multiple lumbar vertebral malformations, mild osteopenia, and variable presence of block vertebrae, most prominent at L3-4 and L6-7. Some mice exhibited lordosis or kyphosis. Lumbar deformities became more prominent at 60 days than they had been at 40 days of age.
Serum biochemical analysis: evidence of protein-losing enteropathy, liver dysfunction, moderate elevation of alkaline phosphatase activity, primarily due to increase of the bone isozyme, and iron profile consistent with functional iron deficiency.
Necropsy: growth retardation encompassing smaller body weight, nose-to-rump and rump-to-tail measurements; marked splenomegaly (especially of red pulp), relatively undersized kidneys, mild cardiomegaly, otherwise uniformly reduced organ sizes. Variable collapse of intervertebral disc spaces, and replacement with dense fibrous tissue (similar in both sexes); pale liver, marked extramedullary hematopoiesis, particularly erythropoiesis in red pulp of spleen, decreased iron concentration in heart, kidneys, and spleen. No extramedullary hematopoiesis was noted in the livers of the hemizygous mutants, but it was prominent in most of the control animals. Bone marrow evaluation: none or only a trace presence of iron found, myeloid-to-erythroid cell ratio (M.E.) increased, reduced % of metarubricytes, microcytic, hypochromic anemia, fewer erythroid precursors were seen.
The authors discuss similarities and differences between this model of scoliosis/kyphoscoliosis and others reported, relative to the condition in humans. Mutant ky mice develop kyphosis, with marked muscular lesions but not the prominent bone lesions common in affected people. Surgically-induced models of scoliosis utilizing destabilization of the vertebral column in rabbits, sheep, rats and chickens are listed, as is scoliosis induced by pinealectomy in chickens. Work connecting poor nutrition to scoliosis in people is referenced, and the hypothesis that iron deficiency may be one of the relevant causal factors is suggested for further study.
Inherited causes of microcytic, hypochromic anemia are reviewed in some detail, including: the Belgrade rat (b), alpha and beta-thalassemia of mice, flexed-tail anemia (f), microcytic anemia (mk), sex-linked anemia (sla), hypotransferrinemic mice (hpx), and the anemia of hemoglobin deficit (hbd) in mice. The beta-hemoglobin locus (Hbb) in mice lies on Chromosome 7 only 4 centimorgans removed from the fit1 locus. Other studies have indicated that the hemoglobin produced by fit1^4226SB^ mutants is normal in structure, suggesting that some positional effect may be at work in causing the observed anemia.
The overall message is that these mice could prove to become useful tools for the elucidation of both scoliosis and hypochromic, microcytic anemia, with possible savings over the costs of using other currently-accepted models of these human diseases, particularly so when compared with the surgically-induced models for scoliosis.
Questions: QUESTIONS:
1. What is ENU? What human conditions can be studied by the use of ENU?
2. Describe chief observations of a mouse hemizygous for the fitness1^4226SB^ mutation.
3. What vertebral condition(s) is/are seen in the fit1 mutant mouse? Name two other animal models of this/these condition(s).
4. Name two other rodent models which express a similar hematologic abnormality to that seen the fit1 mutant mouse.
5. The fitness1 locus in mice is located on the same chromosome as the gene for a significant blood component. Name the chromosome, the blood component, and comment on the relative locations of these loci on the chromosome. Name the coat color locus found on this chromosome in close proximity to Fitness1.
Answers: ANSWERS:
1. ENU is N-ethyl-N-nitrosourea, a mutagenic substance. ENU has been used to produce fitness1 locus mutations in mice. The mutants exhibit scoliosis, lumbar vertebral abnormalities and microcytic, hypochromic anemia, with several characteristics comparable to these same conditions observed in humans, thus potentially being of use in understanding more about these diseases.
2. Mice exhibit runting and nervousness. Serum biochemistry shows reduced iron levels and elevated alkaline phosphatase, particularly of the bone-associated isozyme. The mice have abnormal vertebral columns, with scoliosis and variable kyphosis, lordosis, and presence of block vertebrae, particularly in the lumbar region. On necropsy, splenomegaly is pronounced, especially of the red pulp, where histologically marked extramedullary hematopoiesis can be observed. In the bone marrow, there is an increased M:E ratio. The mice exhibit microcytic, hypochromic anemia.
3. Fit1 mutant mice exhibit scoliosis. Scoliosis models include surgical destabilization of the vertebral column, performed in rabbits, sheep, rats, and chickens. Additionally, surgical pinealectomy in chickens produces scoliosis.
4. The fit1 mutant mouse exhibits microcytic, hypochromic anemia. This condition is also seen in the Belgrade rat (b), alpha and beta-thalassemia of mice, flexed-tail anemia (f), microcytic anemia (mk), sex-linked anemia (sla), hypotransferrinemic mice (hpx), and the anemia of hemoglobin deficit (hbd) in mice.
5. The fitness1 locus lies on mouse Chromosome 7. The locus for beta-hemoglobin (Hbb) is on Chromosome 7, only 4 centimorgans away from the fit1 locus. The chinchilla coat color locus is on Chromosome 7, closely linked to the fit1 locus.

The FLS mouse: a new inbred strain with spontaneous fatty liver. Laboratory Animal Science 49(3), 269.
Abstract: This group has developed a new mouse strain which they name FLS (fatty liver Shionogi) which develops fatty liver without obesity or diabetes. The mouse is characterized by comparison with the DS (dd Shionogi) mouse which is a sister strain from the same laboratory. Other mice showing fatty liver include ob/ob, db,db, fat/fat, tub/tub, and KK, however these mice show obesity. FLS mice show fatty microvesicles in the liver at birth, detectable only by staining with Oil red O, however by 6 weeks of age the fatty vacuoles are larger and can be detected on standard H&E sections at large vacuoles near central veins and diffuse small vacuoles. The DS mice did not show these changes. A grading scheme for steatosis is shown, I-IV with gradually increasing size and distribution of fatty vacuoles. Several physiological and biochemical parameters are compared; those that differed significantly include perirenal adipose tissue, AST and ALT, Cholesterol, Phospholipid, and Glucose. Triglyceride levels, Free fatty acid, and insulin levels were not significantly different. Glycosuria did not occur in either group. Other mice showing fatty liver without obesity include the fld mouse (a mutant of BALB/cByJ), however this mouse shows the liver change only as a neonate and then returns to normal. The FLS mice developed hepatocellular tumors as they aged, for which H. hepaticus was ruled out as a cause. Damage to hepatocytes is suspected to occur due to inflammatory cells, free radical damage, and subsequent mutation and killing of hepatocytes.
The FLS mouse is proposed as a model for the mechanism of fatty liver formation and chronic effects of fatty liver without the presence of obesity or diabetes mellitus.
Questions: Questions:
1. What is the distinguishing feature of FLS mice vs. other strains which develop fatty liver?
2. List two other strains of mice which develop fatty livers.
3. Fatty vesicles are first visible on H&E sections of FLS mouse livers at:
a. 15 weeks of age
b. birth
c. 3 weeks of age
d. 6 weeks of age
e. not visible without special stains
4. Name the fat stain used in this study.
Answers: Answers:
1. FLS mice do not develop obesity or diabetes mellitus.
2. ob/ob, db/db, fat/fat, tub/tub, KK
3. d
4. Oil redO

Statistical method for characterization of hypertrophic cardiomyopathy by use of morphologic and pathologic measurements in pigs (Sus scrofa). Laboratory Animal Science 49(3), 276.
Abstract: The purpose of study was to find morphologic and pathological variables that correlated to HCM by use of statistical methods and to make a linear combination of measurements for classifying HCM in pigs. HCM in pigs is reported to be naturally acquired and is used as an animal model for HCM in people. The most common characteristic morphologic features of HCM are: hypertrophied, nondilated left ventricle, asymmetric hypertrophy of the ventricular septum, marked disorganization of cardiac muscles and abnormal coronary arteries. Randomly selected pigs were sacrificed and hearts were classified morphologically and pathologically according to heart weight, width, heart-to-body weight ratio, thickness of cranial and middle portions of ventricular septum and left ventricular free wall. Combined morphologic and pathologic indices were classified in five groups. 1) normal 2) hypertrophy with rare lesion 3) no hypertrophy but severe lesion 4) moderate hypertrophy with severe lesion 5) hypertrophy with severe lesion. The studied concluded that pig hearts could be characterized as having HCM by fewer morphologic and pathologic features.
Questions: Q1.What morphologic traits of the heart are the most important for characterizing HCM in pigs?
a. heart weight
b. heart width
c. heart length
d. a and b
e b and c
Q2. What areas of the heart are severely affected by HCM in pigs?
a. ventricular septum
b. left ventricle
c. right ventricle
d. a and b
e. none of the above
Answers: A1. d.
A2. d.

Model of Staphylococcus aureus central venous catheter-associated infection in rats. Laboratory Animal Science 49(3), 283.
Abstract: The purpose of the study was to develop a rodent model for nosocomial S. aureus infection of central venous catheters (CVC). Male SD rats were surgically instrumented (jugular vein) with a uniquely constructed lumen-within-lumen Silastic intravenous catheter and then fitted into an animal restraint jacket post-operatively. Forty-eight hours later, 4 groups of animals received the following treatments: Group 1 - inoculated with 100-10000 CFU of S. aureus (derived from a human patient with CVC-associated bacteremia) into catheter lumen and then flushed 15 minutes later, Group 2 - inoculated with 10000 CFU by tail vein, Group 3 - controls, instrumented but no inoculation, Group 4 - controls, no catheter but received 10000 CFU by tail vein. Animals were sacrificed 5-8 days post-inoculation and blood and homogenized tissue samples were cultured. Isolates were characterized by pulse-field gel electrophoresis to ensure that recovered strains were identical to that inoculated.
Animals in Group 1 had the highest number of bacteria recovered from the catheter, blood and tissues. Group 2 animals had very low bacterial numbers and tissue distribution was not as widespread. This model (Group 1) best mimics the human disease, whereby bacterial inoculation occurs most frequently via catheter hubs and intralumenal migration.
Questions: Questions:
1. S. aureus is the most frequent agent of catheter-related bacteremia in humans. T/F
2. What species (other than rat) has commonly been employed as a model to study infective endocarditis? A. mouse B. rabbit C. dog D. sheep
Answers: Answers:
1. F - S. epidermidis
2. B. rabbit

Behavioral Effects of Ivermectin in Mice. Laboratory Animal Science 49(3), 288.
Abstract: Ivermectin is a common anthelmintic used in rodents for treatment of pinworm and mite infestations because of its wide margin of safety, ease of administration, and mechanism of action. Gamma-aminobutyric acid (GABA) is a CNS neurotransmitter in vertebrates and invertebrates. GABA regulates peripheral neurons in nematodes and arthropods. Ivermectin stimulates release of GABA from nerve endings and enhances GABA binding to its receptor, which is on the postsynaptic membrane of an excitatory motor neuron in nematodes and the neuromuscular junction in arthropods. Enhanced binding of GABA to its receptor increases flow of Cl ions into the cell, with subsequent hyperpolarization and elimination of signal transduction which results in paralysis and death of a broad spectrum of parasites (except trematodes and cestodes which don't use GABA as neurotransmitters). Ivermectin has a high safety profile because of its marginal ability of cross the BBB and high-affinity binding of GABA-independent chloride channels in invertebrates, compared with low-affinity binding of GABA-dependent chloride channels in mammals. Ivermectin has been reported to eliminate pinworms and mites (Trichosomoides crassicauda, Syphacia obvelata, S. muris, Myocoptes musculinus, Myobia musculi, Pneumonyssoides caninum, Psoroptes cuniculi, Trixascarus caviae, Chirodiscoides caviae). Ivermectin's effects on behavioral tests in mice were determined in this study.
Materials and Methods: Wild-type 129/SvEv mice were used to measure body weight, open-field locomotor activity and rotarod motor coordination. Inbred C57BL/6J and AKR/J were used to test acoustic startle and sensorimotor gating in prepulse inhibition of startle. C57BL/6J were also used for learning and memory in a Morris water maze. 0.08% sheep drench Ivermectin was given in 8oz. water bottles at 0.008mg/ml for 8 wks. Or water as controls. See text for more complete description of testing. Rotorod measures the ability of a mouse to maintain balance on an accelerating rotating cylinder as a measure of motor coordination and balance. Latency to fall off the rod is significantly reduced in mice with dysfunctions of the cerebellum and spinal cord. Open-field locomotor activity provides a measure of spontaneous exploratory locomotion of a novel environment. Low activity may indicate a motor deficit and/or may reflect high levels of anxiety-like tendencies that inhibit exploration of the illuminated open-space. Acoustic startle response is a cross-species reflexive response to a loud sound stimulus as a measure of hearing and motor reflexes. A loud sound causes the mouse to flinch which is detected and quantified in a stabilimeter device. Prepulse inhibition of acoustic startle is the ability of a prior weak stimulus to inhibit the normal response to a startle stimulus. A quieter tone is delivered before a loud startle tone so that the normal animal will exhibit less of a whole-body flinch when the startle tone is delivered. Morris water task is a spatial navigation task that assesses learning and memory. Mice are trained to swim in a large circular pool or water to find a submerged platform on which they can climb out of the water. Mice locate the platform by learning he spatial relationship between the platform and objects outside the pool. A video system is used to calculate the latency to finding the platform, the swim path, and swim speed.
Results: There was not treatment-related mortality or physical signs of toxicosis in mice treated with Ivermectin. Body weights increased slightly after Ivermectin treatment. Ivermectin had no significant effect of rotorod performance. Ivermectin had a small but significant effect of open-field locomotor activity (mice were more active during ivermectin treatment). C57BL/6J mice treated with ivermectin had significantly greater acoustic startle response amplitude than controls. AKR mice were the same as controls. Percent prepulse inhibition was significantly lower in C57BL/6J and AKR mice treated with ivermectin. Ivermectin had no significant effect on time to locate the hidden platform in C57BL/6J mice. The results indicate that oral ivermectin has significant effects on open-field exploratory locomotor activity (increased motor activity, activating effect of ivermectin in some inbred strains of mice), acoustic startle response (increased, greater reactivity to an unexpected slightly aversive environmental stimulus), prepulse inhibition of acoustic startle (reduced, impaired sensorimotor gaiting). Ivermectin affects the behavioral responses to novel stimuli depending on the inbred strain of mice. However, ivermectin had no significant effects on performance of learning and memory task, or the swimming behaviors required for the task (Morris water maze). It also had no effect on performance of the accelerating rotarod (motor coordination and balance). Body weight is also apparently unaffected. Ivermectin was shown to not affect parameters used to assess rodent health (body weight, general locomotion, motor coordination), but it does have effects on more complicated behavioral tests. It can also have different effects depending on the strain or especially if the animal is a transgenic. Ivermectin toxicity has been reported in transgenics, and newborns.
Conclusions: Although ivermectin does not seem to have adverse effects on physiologic parameters (growth, body weight, reproduction) it seems to have a small but significant effect on behavior and development in some inbred strains of mice. Ivermectin use is contraindicated (or at least use with caution) in laboratory animal facilities when animals must be used for behavioral experiments.
Questions: QUESTIONS:
1) What are the signs of ivermectin toxicosis?
2) When does the blood brain barrier complete its formation in nursing pups?
3) What are the other possible mechanisms of how ivermectin affects behavior?
Answers: Answers:
1) Signs of ivermectin toxicosis include immobility, recumbancy, inability of animals to right themselves, tremors and death.
2) Nursing pups are more sensitive to ivermectin due to high concentrations of the drug in maternal milk and incomplete formation of the BBB until postpartum day 10.
3) It is possible that a small concentration of ivermectin crosses the BBB sufficient for CNS actions; could act as a positive allosteric modulator of nicotinic acetylcholine receptors that are present in mammalian brain and periphery; it could affect the peripheral nervous system or a peripheral organ which then relays sensory information to the brain to influence behavior.

Light-emitting diodes and cool white fluorescent light similarly suppress pineal gland melatonin and maintain retinal function and morphology in the rat. Laboratory Animal Science 49(3), 297.
Abstract: The purpose of the study is compare the effectiveness of a novel light-emitting diode (LED) with that of cool white fluorescent (CWF) light in maintaining normal animal health and well being.
The authors compared the effects of LED light with those of CWF light on: retinal function, using light-induced changes in the electroretinogram (ERG); and retinal morphology using light microscopy and measured light-induced pineal melatonin suppression as an indicator of neuroendocrine function. They compared two light sources in maintaining normal behavioral circadian rhythmicity.
The results indicate that a LED light source can supress pineal gland melatonin concentration in an equivalent manner to a conventional CWF light source at similar intensity levels, and they documented that there are not significant differences in retinal function (ERG) or retinal structure (light microscopy). In addition LED light maintains normal circadian entrainment as assessed throught behavioral parametres.
The authors found that LED light may be a suitable alternative to CWF light for animal-habitat lighting and replacing light sources carries a number of advantatges incuding longer operating life, less mass and volume, less heat production, less power consumption and higher efficiency.
Questions: Questions:
1.- T/F Retinal function is compared using light induced changes in the electroretinograma
2.- T/F Light induced pineal melatonin suppression is an indicator of neuroendrocrine function
Answers: Answers
1.- T
2.- T

Ventricular pressure and dimesntion measurements in mice. Laboratory Animal Science 49(3), 305.
Abstract: A method for measurement of ventricular dimensions and pressure was described in the open thorax mouse. After induction with pentobarbital (60 mg/kg IP), mice were intubated with a 22 gauge soft catheter via a tracheostomy. The heart was approached by a ventral midline incision and ventilation was maintained at a tidal volume of 0.4 ml at 100 cycles/min (fractional inhaled oxygen of 0.21). Ventricular dimensions were obtained by placement of two piezoelectric crystals on the left ventricular epicardium across the short axis at the level of the mitral valve. Ventricular pressure was recorded by placement of a MILLAR pressure catheter introduced through a small incision in the apex of the left ventricle. The evaluation of the pressure-volume relationship provided a means to study cardiac function and left ventricular performance in a load-independent manner.
Genetic alterations in mice has increased available models of heart disease that can help elucidate basic signaling in cardiovascular research. For this reason, miniaturized techniques using microtransducers and echocardiography are a valuable method for assessment of cardiac function. The epicardial placement of the piezoelectric crystals is one limitation to the described technique. Placement in this fashion and resultant intercrystal distances may not reflect actual ventricular volumetric changes.
Questions: QUESTIONS:
1) Piezoelectric crystals are placed:
a) on the epicardial surface
b) at the long axis of the heart
c) at the short axis of the heart
d) at the level of the mitral valve
e) a, c, and d above
2) Name the type of catheter used to obtain pressure measurements.
3) Describe one limitation of this technique.
Answers: ANSWERS:
1) e
2) MILLAR pressure catheter
3) epicardial placement of piezoelectric crystals may not reflect actual ventricular volumetric changes

Natural and experimentally induced infection of Syrian hamsters with a newly recognized parvovirus. Laboratory Animal Science 49(3), 308.
Abstract: Minute virus of mice (MVM), H-1 parvovirus, various strains of Kilham rat virus (KRV), and LuIII parvovirus have been demonstrated experimentally to cause clinical disease in fetal and neonatal Syrian hamsters. Until now, naturally occurring parvoviral disease in Syrian hamsters had not been identified. The authors isolated hamster parvovirus (HaPV), name subject to redesignation, in a large colony of Syrian hamsters. HaPV is most closely related to mouse parvovirus (MPV), with 94.6% genetic homology. Colonies experienced a significant increase in morbidity and mortality among suckling and weanling hamsters. Most affected hamsters were 2-4 weeks old, and had dome-shaped crania and a potbellied appearance. The most striking clinical features were discoloration, malformation and loss of incisor teeth. Affected hamsters also had abnormally small testes. Half of affected animals had proliferative ileitis. They were able to isolate the organism and they used low or high doses of HaPV to infect 3-day-old Syrian hamsters. Animals infected with high doses died 7-8 days after inoculation. Infected hamsters sacrificed 4 days after inoculation did not have gross or histologic lesions, but those killed 7 days after infection had gross lesions including stunted growth, discoloration of the incisors, pale spleen, and petechial to ecchymotic hemorrhagic syndrome involving the gastrointestinal tract, kidneys, testes or uterus, and brain. Spontaneous death was attributed to severe hemorrhagic disease. Animals inoculated with low doses of HaPV were killed at 6 weeks of age. The most striking gross lesions were discoloration, malformation and loss of incisor teeth, and abnormally small testes. Histologic features of this disease included enamel hypoplasia with mineralization and fibrosis of the remaining incisor tissues, suppurative periodontitis, atrophy of the testicular seminiferous tubular epithelium, and multifocal cerebral myelomalacia. Serologic testing indicated seroconversion by use of the NS1, a protein of all characterized rodent parvoviruses, enzyme linked immunosorbent assay (ELISA) and HaPV hemagglutination inhibition (HAI) assays. Using polymerase chain reaction (PCR), they were able to detect HaPV DNA in all tissue samples tested (heart, lung, thymus, brain, liver, kidney, testes or uterus, spleen and intestines). The source of HaPV was not known, but it was suggested that HaPV was carried by a subclinically infected hamster, that HaPV is a mutation of a directly transmitted parvovirus from another species, or that a virus almost identical to HaPV was harbored by an unknown rodent species. The latter was considered most likely.
Questions: QUESTIONS:
1) The most striking features of infection of Syrian hamsters with hamster parvovirus are
a) tooth loss and discoloration
b) testicular atrophy
c) diarrhea
d) a and b
e) none of the above
2) High dose infection of Syrian hamsters with hamster parvovirus leads to multi-systemic hemorrhagic disease
a) True/false
3) Using polymerase chain reaction, they were only able to detect hamster parvovirus DNA in
a) Kidney
b) Testes
c) Spleen
d) Brain
e) All of the above
4) Infection of Syrian hamsters with hamster parvovirus did not have
a) Increase in morbidity and mortality
b) Loss of incisors
c) Polycystic kidneys
d) Hemorrhagic syndrome
e) Testicular atrophy
5) Seroconversion of infected hamsters with hamster parvovirus was detected by
a) Polymerase chain reaction
b) Enzyme linked immunosorbent assay to NS1 protein found in parvoviruses
c) Hemagglutination inhibition specific for HaPV
d) b and c
e) none of the above
Answers: ANSWERS:
1) d
2) true
3) e
4) c
5) d

Identification of pseudocysts of Tritrichomonas muris in Armenian hamsters and their transmission to mice. Laboratory Animal Science 49(3), 313.
Abstract: The purpose of this article was to describe the identification, light microscopic and ultrastructural features, and transmission of oval refractile bodies to protozoa-free outbred mice.
The authors found that:
1) Armenian hamsters are also hosts of T. muris, which has 3 parasitic forms: trophozoite, intermediate form w/ internalized flagella, and the pseudocyst or infective form. This pseudocyst is also easily transmitted to immunocompetent mice as shown in this study.
2) After ultrastructural examination, both Trichomonas cricetus and Tritrichomonas criceti are believed to be synonymous with Tritrichomonas muris. These organisms are not believed to be pathogenic, but they serve as a biomarker of contamination in protozoa-free rodent colonies due to it's low minimal infective dose.
3) Protozoal infection is transmitted via coprophagy of pseudocyst-containing feces-- < 2 days in dry conditions, and 6 to 7 days under moist conditions.
Questions: Questions ???
1. For Fig. 2, p. 314, what type of electron microscope wa used to take the micrograph shown ?
2. What nomenclature symbols are used to designate:
a. oubred stock
b. inbred strain
Answers: Answers:
1. Transmission electron microscope
2. outbred = :
inbred = /

Carbon dioxide-induced anesthesia has no effect on brain biogenic amine concetnrations in mice. Laboratory Animal Science 49(3), 316.
Abstract: The principal criterion in choosing an appropriate method of euthanasia for a laboratory animal is ones ability to induce loss of consciousness and death without causing pain or distress. In studies utilizing mice in which the integrity of the brain tissue is of concern, the animal is commonly killed by manual cervical dislocation, followed by decapitation. Such practices are popular with researchers as they induce rapid death while maintaining the brain tissue in a chemically uncontaminated state. The practices, though, are not without risk, i.e., stress is associated with the physical restraint required to manipulate the conscious animal and there are safety concerns for the handler (bites, scratches, etc.) when manipulating a conscious animal prior to physical euthanasia.
To overcome the risks more and more researchers are using CO2-induced anesthesia prior to cervical dislocation followed by decapitation as a means of euthanasia. There is a concern though by some that CO2 may contaminate neurochemical measures if used in this way. This study examined the effects of CO2-induced anesthesia on measurement of biogenic amine concentrations in the mouse brain using high-performance liquid chromatography (HPLC) with electrochemical detection. Findings indicate that brief exposure to CO2-induced anesthesia (a 70% CO2/30% O2) does not significantly alter concentrations of biogenic amines in the mouse brain. Values obtained in this study agree with those previously reported from other studies of brain catecholamine values without CO2-induced anesthesia.
Questions: No questions

Body Condition Scoring: A rapid and accurate method for assessing health status in mice. Laboratory Animal Science 49(3), 319.
Abstract: The purpose of this study was to develop a non-invasive method for evaluating health and establishing endpoints for mice in experimental protocols resulting in chronic wasting. Traditional methods to establish endpoints in chronic wasting studies have included behavior, physical appearance, and tracking of body weight. Each of these parameters has drawbacks which can lead to misinterpretation of observations. The authors developed a technique for body condition scoring (BCS) similar to those used with agricultural production animals.
To validate their BCS system they chose to assess the health of P- and E-selectin double deficient mice in which organ enlargement is associated with decline in health. The authors chose to correlate BCS, body weight (BW), WBC count, and adjusted body weight (ABW: BW minus mass of tissues prone to enlargement; in this case, salivary glands, mandibular and superficial cervical lymph nodes, and spleen), in both sexes.
24 male and 29 female P/E-selectin -/- mice were selected from a larger population based on their BCS score in order to have an even distribution of BCS scores between male and female groups. Mice were single house for a 2 day observation period, then euthanatized by CO2 inhalation. Blood was collected for WBC counts, BW was measured, and the salivary glands, mandibular and superficial cervical lymph nodes, and spleen were removed and weighed.
BCS was rated on a scale of 1-5 with each integer subdivided into (+) and (-). See descriptions for each rating in text. BCS was evaluated independently by a veterinarian and 2 veterinary technicians. (See diagram in article.)
Results:
1- In male mice BCS, BW, and ABW all had strong correlations with WBC counts, although BCS had the strongest correlation.
2- In female mice, only BCS correlated strongly with WBC counts.
3- The correlation between observer BCS scores was high-- with correlations being slightly higher for male mice.
Conclusions:
1- Because BCS correlated strongly with WBC count (selected index of health status) this study suggests that BCS is a accurate indicator of health status.
2- WBC counts correlated with BW in males, however there was a non-significant correlation between WBC count and BW in females unless the weight of salivary glands, lymph nodes, and spleen were subtracted out for ABW. This finding demonstrates how enlarged organs can cover up loss of fat stores and muscle mass.
3- Advantages of BCS:
1- minimizes disease spread
2- maximize health monitoring because BCS is easier and quicker to perform than BW determinations
3- no reference weights are necessary to evaluate results
4- The difference between use of BW between males and females was attributed to higher percent BW being attributed to enlarged organs/tissues in females. This may be true most likely because females have a smaller frame size, lower average BW, and a greater increase in tissue mass in response to disease.
5- It is necessary to evaluate the BCS system in tumor, aging, and mutant phenotyping models to see whether it can help to establish more consistent, humane endpoints.
Questions: No questions

Spontaneous low-virulence mouse hepatitis virus infection in severe combined immunodeficiency mice. Laboratory Animal Science 49(3), 324.
Abstract: This paper describes a natural outbreak of MHV (mouse hepatitis virus) in SCID mice. MHV strains are referred to as either enteric or respiratory based on whether the virus replicates predominantly in the intestines or the lungs. Virulence also varies among strains and animal susceptibility also varies (C3H are considered resistant, BALB/c and C57BL are highly susceptible). In this paper a mouse strain referred to as FGS (focal glomerular sclerosis) seroconverted to MHV but did not show lesions on histologic examination. C.B-17 Prkdc SCID mice showed emaciation, dehydration and weight loss on clinical examination and five mice died 1-2 weeks after the onset of clinical signs. Gross necropsy findings consisted of multiple white pinpoint foci throughout the liver. Histologic findings included necrotic foci in the liver with a predominantly neutrophilic inflammatory infiltrate and multinucleated giant cells. The lungs ranged from normal to congested with edema. Immunohistochemistry revealed positive hepatocytes at the periphery of the necrotic foci. Positive cells were also seen in the brain (cerebral cortex & medulla ablongata) and alveolar macrophages.
Questions: Questions:
1) What type of virus causes MHV?
2) What strains of mice are considered resistant? sensitive?
3)What clinical signs are seen in SCID mice with MHV?
Answers: Answers:
1) Coronavirus
2) C3H are considered resistant; DBA, BALB/c, and C57BL are sensitive; also sensitive are athymic and SCID mice
3) Acute death or chronic wasting syndrome

Percutaneous intravenous injection in neonatal mice. Laboratory Animal Science 49(3), 328.
Abstract: A noninvasive percutaneous method for intravenous injection into mice ranging from several hours to 4 days of age was described. Specialized equipment is not required. Volumes up to 100 ml can be injected successfully with a frequency >90%.
Intravenous injections in newborn mice were performed through the superficial temporal vein. This is a prominent vessel located on either side of the head. It is visible just below the eye, travels toward the neck, and bisects the jugular vein.
Injections of 100 ml were delivered through a 30- gauge, 1 /2-in. needle (Becton Dickinson, Franklin Lakes, N.J.) attached to a 1-ml tuberculin syringe (Becton Dickinson). Although the injections can be performed without use of magnification, a 6x power magnifying glass surrounded by a fluorescent light source greatly facilitates the injection procedure. This newborn intravenous injection technique has been invaluable for studies in a murine model of the lysosomal storage disease mucopolysaccharidosis type VII (MPS VII). By using this technique, early initiation of treatments, such as bone marrow transplantation , direct enzyme replacement, or adeno-associated virus-mediated gene transfer in MPS VII-affected mice, was found to be more efficacious than if treatment was delayed until 4 to 6 weeks of age.
Questions: Questions:
1)Where is the superficial temporal vein located?
a) Next to the medial canthus of the eye
b)Superior to the ears
c)just below the eyes
d)on the top of the head
2) Why did the authors develop this technique?
a)for their lysosomal storage disease mucopolysaccharidosis type VII model
b)for their glucose tolerance test model
c)for their agangliosis model
d)for their cystic fibrosis model
Answers: Answers:
1) c
2) a

Rat model for dual opportunistic pathogen prophylaxix: Cryptosporidium parvum and Pneumocystis carinii. Laboratory Animal Science 49(3), 331.
Abstract: Cryptosporidium parvum and Pneumocystis carinii are two common causes of opportunistic infections in immunosuppressed patients. Many patients need to take multiple drugs to prevent or combat opportunistic infections. Multiple opportunistic pathogen prophylaxis strategy (MOPPS) is an approach under investigation for AIDS patients to try to treat multiple pathogens with the same drugs.
This paper reports on use of a rat model for MOPPS evaluation. Female HSD rats 12 to 16 weeks of age were immunosuppressed with dexamethasone in water. This group had previously found that Pneumocystis infection will occur in so treated rats 3 weeks after immunosuppression. The animals were infected with C. parvum orally on day 10 of immunosuppression. Several drugs or combinations of drugs were administered to the animals. The most successful against both pathogens was the combination of azithromycin and trimethoprim-sulfamethoxazole. Other drugs successfully treated one pathogen with little effect on the other. Medications were given in food, with concentration in food based on predicted consumption and desired dose. This worked well in that as animals changed in weight, their appetite changed similarly.
The authors found that concurrent infection with two pathogens did not markedly modify the course of infection with either organism. The antibiotic profiles of some of the drugs were also similar to tests in animals infected with only one organism. Thus the model discussed allows screening of drugs for two infections simultaneously, minimizing time and number of animals required.
Questions: Questions:
1. List two or more common opportunistic pathogens in immunocompromised hosts.
2. Define MOPPS.
3. What is the advantage of testing multiple pathogens simultaneously?
Answers: Answers:
1. Cryptosporidium parvum, Pneumocystis carinii, Toxoplasma gondii, Giardia lamblia
2. MOPPS is an acronym for "multiple opportunistic pathogen prophylaxis strategy".
3. Time and number of animals needed for testing is reduced. Effectiveness of drugs or drug combinations in combating more than one infection simultaneously can be studied.