Survey of laboratory animal technicians in the United States for Coxiella burnetii antibodies and exploration of risk factors for exposure.

Little is known about the prevalence of zoonotic infections among laboratory animal care technicians (LAT). Q fever, a disease caused by Coxiella burnetii, is a known occupational hazard for persons caring for livestock. We sought to determine the seroprevalence of C. burnetii antibodies among LAT and to identify risk factors associated with C. burnetii seropositivity. A survey was administered and serum samples collected from a convenience sample of 97 LAT. Samples were screened by using a Q fever IgG ELISA. Immunofluorescent antibody assays for phase I and phase II IgG were used to confirm the status of samples that were positive or equivocal by ELISA; positive samples were titered to endpoint. Antibodies against C. burnetii were detected in 6 (6%) of the 97 respondents. In our sample of LAT, seropositivity to C. burnetii was therefore twice as high in LAT as compared with the general population. Age, sex, and working with sheep regularly were not associated with seropositivity. Risk factors associated with seropositivity included breeding cattle within respondent's research facility, any current job contact with waste from beef cattle or goats, and exposure to animal waste during previous jobs or outside of current job duties. Only 15% of responding LAT reported being aware that sheep, goats, and cattle can transmit Q fever. Research facilities that use cattle or goats should evaluate their waste-management practices and educational programs in light of these findings. Additional efforts are needed to increase awareness among LAT regarding Q fever and heightened risk of exposure to infectious materials. Physicians should consider the risk of infection with C. burnetii when treating LAT with potential occupational exposures.

Analgesic effects of meloxicam, morphine sulfate, flunixin meglumine, and xylazine hydrochloride in African-clawed frogs (Xenopus laevis).

We evaluated analgesic use and analgesiometry in aquatic African-clawed frogs (Xenopus laevis). We used the acetic acid test (AAT) to assess the analgesic potential of systemic xylazine hydrochloride, meloxicam, flunixin meglumine, and morphine sulfate after injection into the dorsal lymph sac. Flunixin meglumine provided better analgesia than did the other drugs, most evident at 5 and 9 h after administration. Because the AAT was associated with the development of dermal lesions, we discontinued use of this assay and chose the Hargreaves test as an alternative method of measuring nociception in Xenopus. This assay is commonly performed in rodents, but its efficacy in an aquatic species such as Xenopus was unknown prior to this study. We found that the Hargreaves test was an effective measure of nociception in Xenopus, and we used it to evaluate the effectiveness of the nonopiod agents xylazine hydrochloride, meloxicam, and flunixin meglumine both in the absence of surgery and after surgical oocyte harvest. Similar to findings from the AAT, flunixin meglumine provided better analgesia in the Hargreaves test than did the other agents when analyzed in the absence of surgical intervention. Results were equivocal after oocyte harvest. Although surgical oocyte harvest is a common procedure in Xenopus, and currently there are no published recommendations for analgesia after this invasive surgery. Future studies are needed to clarify the efficacy of nonsteroidal antiinflammatory drugs for that purpose.

Cyclosporine-induced gingival overgrowth in New Zealand White rabbits (Oryctolagus cuniculus).

A high incidence of gingival overgrowth occurred in a group of New Zealand White rabbits receiving daily cyclosporine (15 mg/kg IM) while on a retinoblastoma study. Over the course of 2 mo, rabbits presented with clinical signs of ptyalism (4 of 18 rabbits), inappetence (3 of 18), or both (3 of 18); facial dermatitis and erythema occurred secondary to ptyalism. Reducing the dose of cyclosporine to 10 mg/kg led to complete resolution of clinical signs in all but 2 rabbits, which then received azithromycin (62.5 mg PO once daily for 7 d), a common treatment for cyclosporine-induced gingival overgrowth in other species. After dose reduction and azithromycin treatment, clinical signs resolved and did not reoccur for the remainder of the study. Fourteen rabbits were necropsied at the end of the study, and gingival width was measured. Although some rabbits were clinically normal, the gingiva in all rabbits was grossly thickened. Rabbits on cyclosporine had molar gingiva that was significantly thicker (4.8 mm) than controls (2.5 mm) not treated with cyclosporine. Histologic analysis of the gingiva revealed mild to moderate gingival epithelial hyperplasia, hyperkeratosis, and mild inflammation. Gingival overgrowth is a known side effect of cyclosporine administration in other species but, to our knowledge, this report is the first description of the condition in rabbits. Because rabbits frequently are used in studies that involve systemic cyclosporine administration, clinicians are advised to include this possibility in their differential list for cases involving hypersalivation, facial dermatitis, or inappetence in rabbits.

Moxidectin toxicity in senescence-accelerated prone and resistant mice.

Moxidectin has been used safely as an antiparasitic in many animal species, including for the eradication of the mouse fur mite, Mycoptes musculinus. Although no side effects of moxidectin have previously been reported to occur in mice, 2 strains of the senescence-accelerated mouse (SAMP8 and SAMR1) sustained considerable mortality after routine prophylactic treatment. To investigate the mechanism underlying this effect, moxidectin toxicosis in these mice was evaluated in a controlled study. Moxidectin was applied topically (0.015 mg), and drug concentrations in both brain and serum were analyzed by using HPLC coupled with mass spectrometry. The moxidectin concentration in brain of SAMP8 mice was 18 times that in controls, and that in brain of SAMR1 mice was 14 times higher than in controls, whereas serum moxidectin concentrations did not differ significantly among the 3 strains. Because deficiency of the blood-brain barrier protein P-glycoprotein leads to sensitivity to this class of drugs in other SAM mice, Pgp immunohistochemistry of brain sections from a subset of mice was performed to determine whether this commercially available analysis could predict sensitivity to this class of drug. The staining analysis showed no difference among the strains of mice, indicating that this test does not correlate with sensitivity. In addition, no gross or histologic evidence of organ toxicity was found in brain, liver, lung, or kidney. This report shows that topically applied moxidectin at a standard dose accumulates in the CNS causing toxicosis in both SAMP8 and SAMR1 mice.

Isoflurane waste anesthetic gas concentrations associated with the open-drop method.

The open-drop technique is used frequently for anesthetic delivery to small rodents. Operator exposure to waste anesthetic gas (WAG) is a potential occupational hazard if this method is used without WAG scavenging. This study was conducted to determine whether administration of isoflurane by the open-drop technique without exposure controls generates significant WAG concentrations. We placed 0.1, 0.2, or 0.3 ml of liquid isoflurane into screw-top 500 or 1000 ml glass jars. WAG concentration was measured at the opening of the container and 20 and 40 cm from the opening, a distance at which users likely would operate, at 1, 2, or 3 min WAG was measured by using a portable infrared gas analyzer. Mean WAG concentrations at the vessel opening were as high as 662 +/- 168 ppm with a 500 ml jar and 122 +/- 87 ppm with a 1000 ml jar. At operator levels, WAG concentrations were always at or near 0 ppm. For measurements made at the vessel opening, time was the only factor that significantly affected WAG concentration when using the 500 ml jar. Neither time nor liquid volume were significant factors when using 1000 ml jar. At all liquid volumes and time points, the WAG concentration associated with using the 500 ml container was marginally to significantly greater than that for the 1000 ml jar.

Use of selamectin and moxidectin in the treatment of mouse fur mites.

A breeding colony consisting of 250 different strains of mice was treated with the topical acaricide selamectin for the mouse fur mite Myocoptes musculinus, with no apparent ill effect, suggesting that this drug is safe for use in mice. To further evaluate their efficacy in treating Myocoptes spp., we compared selamectin with another acaricide, moxidectin, in a controlled manner. Infested mice were treated with selamectin or moxidectin at the time of cage change, and a subset of mice was retreated 10 d later. Mice underwent routine cellophane tape examination of the pelage for 1 y. Although no adult mites were found in any group at 1 mo after treatment, egg casings were found in the selamectin treatment group as late as 6 mo after treatment, prompting concern about its effectiveness. Moxidectin used in combination with cage changing was effective in eradicating mites, with mice negative for traces of mites on cellophane tape examination of the pelage from months 2 through 12 after treatment.

Effects of interferon-alpha on rhesus monkeys: a nonhuman primate model of cytokine-induced depression.

BACKGROUND: Interferon (IFN)-alpha is an innate immune cytokine that causes high rates of depression in humans and therefore has been used to study the impact of cytokines on the brain and behavior. To establish a nonhuman primate model of cytokine-induced depression, we examined the effects of IFN-alpha on rhesus monkeys. METHODS: Eight rhesus monkeys were administered recombinant human (rHu)-IFN-alpha (20 MIU/m(2)) or saline for 4 weeks in counterbalanced fashion, and videotaped behavior, as well as plasma and cerebrospinal fluid (CSF), were obtained at regular intervals to assess behavioral, neuroendocrine, immune, and neurotransmitter parameters. Additionally, expression and activity of IFN-alpha/beta receptors in monkey peripheral blood mononuclear cells (PBMCs) were assessed. RESULTS: Compared with saline treatment, IFN-alpha administration was associated with persistent increases in anxiety-like behaviors and decreases in environmental exploration. In addition, IFN-alpha induced significant increases in plasma concentrations of corticotropin (ACTH), cortisol, and interleukin-6 that tended to diminish after chronic administration, especially in dominant animals. Interestingly, in three animals, depressive-like, huddling behavior was observed. Monkeys that displayed huddling behavior exhibited significantly higher plasma concentrations of ACTH and lower CSF concentrations of the dopamine metabolite homovanillic acid. Rhesus monkey PBMCs were found to express mRNA and protein for the IFN-alpha/beta receptor. Moreover, treatment of PBMCs with rHu-IFN-alpha led to induction of STAT1, one of the primary IFN-alpha-induced signaling molecules. CONCLUSIONS: IFN-alpha evoked behavioral, neuroendocrine, and immune responses in rhesus monkeys that are similar to humans. Moreover, alterations in hypothalamic-pituitary-adrenal axis responses and dopamine metabolism may contribute to IFN-alpha-induced depressive-like huddling behavior.

Investigation of appropriate sanitization frequency for rodent caging accessories: evidence supporting less-frequent cleaning.

The Guide for the Care and Use of Laboratory Animals states that sanitization of caging accessories (for example, filter tops and wire-bar lids) should be done every 2 wk. In this study we tested the hypothesis that organic contamination measured by the presence of ATP associated with organic material (measured with luciferase test swabs) and the number of bacterial colony-forming units (as determined by use of replicate organism detection and counting plates) on caging accessories did not differ significantly at 2 wk versus several months of use. The study evaluated 4 groups: mouse and rat ventilated and static wire-bar cages with or without filter tops (n = 10 per group). The cages were evaluated at several time points from 2 wk to 6 mo. For every cage type, ATP levels did not differ significantly between 14 and 90 d and, in most cases, between 14 and 180 d. In addition the number of bacterial colonies did not differ significantly between 14 and 120 d (and, in some cases, between 14 and 180 d). This study provides data relevant to establishing a validated frequency for sanitization of rodent caging accessories while controlling, and potentially decreasing, costs associated with sanitization.

Tamoxifen fails to affect central serotonergic tone but increases indices of anxiety in female rhesus macaques.

The selective estrogen receptor modulator (SERM), tamoxifen, effectively slows the progression of estrogen-positive breast cancer and aids in the prevention of cancer in at-risk women. Tamoxifen is well characterized with regards to its effects on breast cancer, but its effects on other estrogen-related systems, particularly neural circuits regulating brain function and mood, are poorly understood. Using ovariectomized rhesus monkeys, we examined the effects of tamoxifen, with and without estrogen replacement therapy (ERT), on social behavior and central serotonin (5HT) systems thought to influence these behaviors. Relative to placebo treatments, estrogen treatment increased serotonergic tone, based on response in prolactin and cortisol to fenfluramine, a 5HT releasing agent. Tamoxifen neither blocked nor enhanced this effect, indicating it to be neither an antagonist nor an agonist on serotonergic activity. In contrast, CSF measures of the 5HT metabolite, 5HIAA, were not significantly affected by treatment. Tamoxifen-treated animals showed increases in measures of anxiety, compared with ERT-treated animals, suggesting that this SERM may be anxiogenic. Co-treatment with estrogen attenuated the anxiogenic properties of tamoxifen. These data show that tamoxifen administration increased anxiety levels, but the affect was not associated with differences in central levels of the serotonin tone.

Urolithiasis associated with experimental lymphocytic choriomeningitis virus inoculation in Lewis rats.

A high frequency of struvite urolithiasis, hydronephrosis, and other urinary tract lesions developed in a group of Lewis rats inoculated intracranially with lymphocytic choriomeningitis virus (LCMV). Initially, clinically ill rats were referred to necropsy: 30 rats over 3 years. These rats had high frequency of urolithiasis (8/30, 27%), hydronephrosis (12/30, 40%), cystitis (9/30, 30%), transitional cell carcinoma (4/30, 13%), and pyelonephritis (19/30, 63%). Lesions were more common in LCMV-inoculated rats. After this trend was noted, all rats on this protocol were necropsied as part of a cohort study (n = 144). Although the apparent frequency of disease was lower due to increased sampling, there still was a high number of urolithiasis (9/144, 6%) and hydronephrosis (40/144, 28%) cases. All cases of urolithiasis developed in rats inoculated with LCMV (9/44, 20%), as did most cases of hydronephrosis (31/44, 70%). Although sham-injected and uninoculated control rats also had high frequency of hydronephrosis (6/57 [11%] and 3/43 [7%], respectively), LCMV-inoculated rats had a significantly higher frequency of disease than did sham inoculated (P < 0.0001) and uninoculated (P < 0.0001) controls. These results suggest that Lewis rats may be predisposed to developing lesions of the urinary tract, and that intracranial inoculation of rats with LCMV augments this tendency, leading to formation of struvite calculi and associated urinary tract disease.

Cutaneous acariasis in the African clawed frog (Xenopus laevis).

Increased mortality was observed in a single colony of 50 Xenopus laevis. The frogs were used as oocyte donors in developmental biology studies. Necropsy findings included dermal erythema and petechiation consistent with red leg syndrome; dermal ulcerations and white, filamentous growths on the skin were consistent with Saprolegnia sp. Microscopic evaluation of the skin and fungus revealed an astigmatid mite similar to those of the genus Rhizoglyphus. The mite was also found in the water and the biological filter of the tanks housing the frogs. This mite is considered not to be a parasite of X. laevis; instead, it feeds off moss, fungi, and detritus. Subsequent evaluation of the sphagnum moss used for shipping the frogs from the supplier revealed the same mite in the moss. Our hypothesis is that the mite was introduced into the tank with the shipment of new frogs in sphagnum moss. The mites lived within the biological filter, and were only found after the growth of Saprolegnia sp. attracted the mites to the frogs. Laboratory animal care and veterinary personnel should consider non-pathogenic species of mites in the differential diagnosis of acariasis in Xenopus frogs.

Leptin administration increases nocturnal concentrations of luteinizing hormone and growth hormone in juvenile female rhesus monkeys.

The importance of leptin in regulating sexual maturation is supported by data showing that deletions of the leptin gene or alterations in the leptin receptor result in infertility. However, attempts to define a role for leptin in normal puberty have produced equivocal results, leading to the conclusion that, if leptin is involved in puberty, its role is permissive and not obligatory. To better define the importance of leptin in primate puberty, the present study tested the hypothesis that a premature elevation in nocturnal leptin concentrations would accelerate indices of puberty, including nocturnal LH secretion in female rhesus monkeys (Macaca mulatta). Juvenile, gonadally intact females were treated daily with leptin (n = 6; 30 micro g/kg, sc at 1700 h) from 12-30 months of age and were compared with age-matched control females (n = 13). Chronic elevation in peripheral concentrations of leptin increased serum levels of both daytime and nighttime bioactive LH at a significantly younger age compared with control females. The earlier rise in LH in leptin-treated females was associated with an earlier increase in serum estradiol and occurrence of menarche. Despite this effect of leptin, nocturnal serum LH was significantly higher at each age assessed in non-leptin-treated ovariectomized controls (n = 6). In addition, leptin increased skeletal lengths and maturity that were associated with significantly higher serum levels of nocturnal GH and daytime IGF-I. Although body weights were not consistently affected by treatment, body mass index, as an index of body fat, was consistently lower in leptin-treated females. Taken together, these data indicate that the chronic elevation in serum leptin concentrations advances the nocturnal increase in serum LH as well as other parameters of female puberty. Furthermore, the observation that nocturnal LH was higher in age-matched, agonadal females compared with the leptin-treated females suggests that the nongonadal drive to LH secretion is operative in female macaques as early as 14 months of age, suggesting that the effect of leptin on puberty in female primates may involve a diminution in gonadal negative feedback suppression of LH secretion. Such a role would suggest that leptin is permissive yet critical for advancing female puberty.

Gastric trichobezoars in a rhesus macaque (Macaca mulatta).

On physical examination, a 5 x 10-cm abdominal mass was found in an eight-year-old female rhesus macaque. Radiography revealed an opaque mass in the cranial portion of the abdomen, displacing the stomach craniad. Percutaneous biopsy obtained hair with little tissue, confirming a diagnosis of trichobezoar. Initially, the hairball was medically managed by oral administration of lubricants. Medical management proved unsuccessful, the macaque began to lose weight, and two gastric trichobezoars were subsequently removed surgically. Normal appetite and activity were regained within one week. Gastric trichobezoars may lead to severe clinical illness, and should be considered in the differential diagnosis for anorexia and/or weight loss in any nonhuman primate. Trichobezoars may also be detected and treated prior to development of illness.