Contemporary topics in laboratory animal science最新文献

Relocation of research animals, either within a facility or from one facility to another, is assumed to be stressful. Development of appropriate research methodologies may be facilitated by understanding the extent and duration of the physiological response to relocation stress and whether the stress can be buffered by environmental or social factors, such as the presence of a cagemate. To characterize the response to relocation stress in Garnett's bushbaby, we assessed cortisol concentrations in nine female and six male bushbabies during relocation to a different facility; six of the animals were pair-housed at the time of the move and were moved with their respective cagemates. Fecal cortisol was assessed at three time points: 1) baseline (1 day prior to moving); 2) relocation (the day the animals were relocated); and 3) post-relocation (7 days after relocation). Cortisol concentrations were higher at the relocation time point than at baseline and post-relocation, which did not differ. Cortisol concentration did not differ as a function of having a cagemate during relocation. Although relocation resulted in a significant (P < 0.05) increase in cortisol excretion concentration, the levels returned to baseline within 7 days after the stressor.

The unanticipated underutilization of chimpanzees (Pan troglodytes) by the National Institutes of Health (NIH) for current NIH-supported research has prompted the application of a variety of contraceptive forms. Among the many methods attempted, the intrauterine device (IUD) has been described as having an efficacy similar to that described for humans. In addition, the device is both a financially sound and practical solution to prevention of overpopulation, while minimizing disruption of normal cyclic hormonal fluctuations. However, variations in the size and shape of the sexual skin of the female chimpanzee and the depth of the vaginal vault have posed physical constraints on the use of instrumentation developed for humans for assisting with insertion of the device. In addition the literature is lacking in specific methodology for pelvic examination in chimpanzees. Previously, the University of Louisiana at Lafayette New Iberia Research Center used a 3-ml plastic syringe case as a vaginal speculum to accommodate requirements of an approved research protocol in African green monkeys (Chlorocebus aethiops). Similarly, a simple and effective disposable vaginal speculum was developed for the chimpanzee. The closed tip of a plastic syringe case of appropriate size (20 to 60 ml) was removed to provide an open tube; momentary heating smoothed the cut edge. This simple speculum allowed for sufficient visualization of the cervix for assessment and assistance in the insertion of the IUD. Variously sized speculums were prepared to accommodate differences in animal size. This simple and effective speculum was clean, disposable, and inexpensive.

A large animal with diminished cardiac function would be desirable for chronic testing of pathophysiologic responses to many human-sized devices and other therapies, especially if this model did not require prior surgical interventions or extensive technical skill and expense. Overdoses of monensin, widely used in the cattle industry as a growth promotant, are cardiotoxic, suggesting its possible use in creating cardiomyopathy. We gave a single oral dose of monensin (20 to 40 mg/kg) to 13 calves (55 to 90 kg) to produce diminished cardiac function. Hemodynamics and cardiac geometry were monitored for as long as 21 days postinduction. Within 3 days, there were signs of decreased cardiac function, as evidenced by a 10- to 20-mm Hg decrease in peak systolic blood pressure (P < 0.01 versus baseline) and a 2- to 9-mm Hg increase in central venous pressure (P < 0.01 versus baseline). There was a trend towards an increase in left ventricular end-systolic lumen diameter. Compared with those of similar-sized normal animals, stroke volume was 42% lower (P < 0.05), left atrial pressure was 67% higher (P < 0.01), and end-diastolic left ventricular pressure was 143% higher (P < 0.05). Histopathologic analysis showed extensive cardiomyocyte death. These results suggest that monensin could provide a simple, noninvasive, inexpensive, and likely irreversible means of producing clinically relevant diminished cardiac function in a human-sized animal model.

We conducted a hatchery growth study to describe the variability in growth rates, spawning, and mortality of Aplysia californica in regard to rearing temperature. Animals were housed at a standard hatchery density of five animals per cage, at temperatures of 13, 15, 18, and 21 degrees Celsius. Animals reared at 13 or 15 degrees C grew as much as four times as large, lived twice as long, matured later, and spawned longer than did animals reared at 18 or 21 degrees C. At age 170 to 205 days the fastest growth rates occurred at 18 and 21 degrees C, and the slowest at 13 degrees C. As animals at 18 and 21 degrees C reached sexual maturity at ages 190 to 197 days, or approximately 60% through their lifespans, their growth rates slowed such that by age 260 days, the fastest growth rate was at 13 degrees C, and the slowest was at 21 degrees C. Animals reared at 13 and 15 degrees C reached sexual maturity at 242 and 208 days, respectively, or at approximately 40% of their life spans. Lifespan and maximum average animal weight were significantly inversely correlated with temperature (P

A 4.5-year-old female degu (Octodon degus) was minimally responsive with a poor body condition, a rough haircoat, and moderate dehydration. Blood was present around its urethral orifice and on the cage bedding. Laboratory analyses revealed leukocytosis with neutrophilia and anemia; hypoproteinemia and hypoalbuminemia; hyperglycemia, hyperphosphatemia, and elevated alanine aminotransferase, blood urea nitrogen, and creatinine; and hematuria and pyuria with occasional squamous and transitional epithelial cells. A urine culture was positive for coagulase-negative Staphylococcus sp. On gross necropsy, the right kidney was enlarged, cystic, and greenish-brown, with a 10-mm, hemorrhagic, granular mass extending from the renal pelvis into the cranial cortex. Only a small amount of renal cortex appeared normal. The urinary bladder had focal areas of hemorrhage and contained frank blood. Histologically, the papillary mass in the right renal pelvis comprised basophilic, moderately anaplastic, clustered epithelial transition cells consistent with a transitional cell carcinoma. Internally, the tumor showed squamous metaplasia and moderate multifocal interstitial fibrosis. The right kidney cortex contained a choristoma comprising trabecular bone, mature adipocytes, and cellular infiltrates suggestive of osteocytes, lymphocytes, and plasma cells. The urinary bladder had mild to moderate, focal, hemorrhage with neutrophilic inflammation and contained focal areas of mild transitional cell epithelial hyperplasia; these changes may have been secondary to irritation by hemorrhage in the renal pelvis. There was no evidence of metastasis. Renal transitional cell tumors are rare in rodents. This is the first report of both a renal transitional cell carcinoma and a renal choristoma in a degu.

We sought to determine the effects of gender on cardiovascular function of spontaneously hypertensive (SH) rats under basal conditions and after several common husbandry and experimental procedures. Heart rate (HR) and mean arterial blood pressure (MAP) were monitored by radiotelemetry during undisturbed periods in the morning, at night, and after acute and chronic procedures. When undisturbed in the morning and at night, female rats had significantly (P < 0.05) higher HR than male rats, whereas male rats had significantly (P < 0.05) higher MAP. In response to all the acute procedures examined except prolonged restraint and introduction of an intruder rat of the same sex, female rats had significantly (P < 0.05) greater changes in HR or MAP than did male rats. In contrast, male rats had a greater change in MAP in response to prolonged restraint (P < 0.05) and greater HR and MAP responses (P < 0.05) in response to an intruder rat. Likewise, chronic exposure to an intruder rat increased HR and MAP significantly (P < 0.05) more in males than females, and both strains partially adapted to the introduction of the unfamiliar rat after the first day. There were no significant sex-associated differences in the HR or MAP responses to transport and subcutaneous injection on four consecutive days, and neither male nor female rats adapted to the repeated procedure. We conclude that sex-associated differences in cardiovascular responses do occur in SH rats, but the direction of the difference varies with the stimulus used.

A female, wild-caught, rhesus macaque (Macaca mulatta), in captivity for 23 years and estimated to be older than 26 years, had an 8-year history of progressive spinal curvature. Scoliosis was initially noted 1 year after a therapeutic bilateral ovariectomy to treat endometriosis. Eight years after the initial diagnosis, the curvature had progressed to a structural (nonflexible), lumbar scoliosis with a curvature to the left and a structural thoracolumbar kyphosis. The spinal curvature was characterized radiographically by a severe, major lumbar curve to the left with vertebral rotation and severe thoracolumbar kyphosis. The Cobb method of measurement identified a major left lumbar curve of 80 degrees. When the animal's condition deteriorated, the animal was euthanized, and a necropsy with postmortem radiographic and microscopic examination was performed. Radiographically and grossly, multiple intervertebral disc spaces were narrowed along the entire spine with ventral bridging intervertebral spondylosis of the lumbar spine. Radiographically, vertebral bodies appeared to be less radiodense and multiple features of degenerative disc disease were present. No clinical evidence of concurrent neuromuscular or mesenchymal disease was noted, and development of lesions after bilateral ovariectomy suggested the kyphoscoliosis was secondary to osteopenia that developed as the result of a surgically induced estrogen deficiency.