Contemporary topics in laboratory animal science最新文献

We sought to determine whether the post-traumatic pathology in the rabbit knee induced by anterior cruciate ligament (ACL) transection is a model of cartilage injury and repair (i.e., irreversible osteoarthritis) or one in which phases of degeneration and regeneration occur. After knee instability was induced in 15 New Zealand White rabbits by ACL transection, the animals were separated into two groups according to the time of euthanasia (i.e., 8 weeks [n = 9] or 16 weeks [n = 6] after ACL transection). The macroscopic parameters evaluated were location, type, and extent of articular changes. The microscopic parameters evaluated were morphology of the articular cartilage and subchondral bone (degeneration indices) and articular cartilage thickness, chondrocyte arrangement, and chondrocyte metabolic activity (regeneration indices). A total score of all histological sections from each animal was based on a modified Mankin's grading system characterizing the progression of osteoarthritic damage. The only statistically significant differences (P < 0.05) between groups were those regarding chondral thickness, chondrocyte arrangement, and metabolic activity, indicating repairing of the articular cartilage. ACL transection led to rapid osteoarthritic changes during the first 8 weeks. However, during the later post-traumatic period, these changes progressed slowly because of a concurrent repair effort. Therefore, this experimental animal model offers investigators the choice of which phase-degenerative (early) or regenerative (late)-is most appropriate for their research purposes.

Infections with mouse coronavirus (also known as mouse hepatitis virus, MHV) are common and prompt concern because the adverse research effects of infection have been well documented. The animal facility we describe had contained an enzootic infection of mouse coronavirus for more than a decade. Eradication of the virus had been tried with limited success in the past. With an increase in the populations of immune-compromised and transgenic animals elsewhere in the facility, eradication of the virus became a high priority. The affected animals were in multiple breeding colonies comprising more than 4000 mice representing more than 50 site-specific strains, lines, and sublines. A task force designed to ensure representation of all interested parties developed a multi-phase approach which included (a) culling of nonessential animals, (b) cessation of breeding, (c) testing and culling of individual animals, and (d) cross-fostering to clean dams. To date, all of the strains, lines, and sublines manipulated through this multi-phase eradication approach continue to test negative for mouse coronavirus. This multi-phase approach may be useful for other institutions attempting to eradicate mouse coronavirus.

We sought to determine whether any of the common methods of euthanasia for adult rodents would lead to an acceptable death for fetuses or neonates. We wanted to identify a method that was rapid, free of signs of pain or distress, reliable, and minimally distressful to the person performing the procedure and that minimized the amount of handling required to perform the procedure. We evaluated six methods of euthanasia, with and without anesthesia, in three age groups of mice: gravid mice (E14-20) and neonatal pups (P1-P7 and P8-P14). Euthanasia methods included: halothane inhalation, carbon dioxide inhalation, intraperitoneal sodium pentobarbital, intravenous potassium chloride, and cervical dislocation with and without anesthesia. Noninvasive echocardiography was used to assess heartbeat during euthanasia. With cardiac arrest as the definition of death, no method of euthanasia killed fetal mice. Halothane inhalation (5% by vaporizer) was not an acceptable method of euthanasia for mice of the age groups tested. Intraperitoneal administration of sodium pentobarbital for euthanasia required a higher dose than the previously established dose, and there is a risk of reduced efficacy in pregnant animals due to potential intrauterine injection. Carbon dioxide asphyxiation was the most efficient method of euthanasia for neonatal mouse pups P1-14. For pregnant adult mice, intravenous potassium chloride under anesthesia, carbon dioxide asphyxiation, and cervical dislocation alone or under anesthesia were excellent methods of euthanasia.

When designing, developing, and testing pharmaceutical compounds, scientists rely on available data about the environmental pH of the target organ--in this case, the vaginal tract--for determining maximum absorption. In this study, we compared two commercially available pH papers with a handheld digital pH meter to assess their viability as methods for measuring vaginal pH in cynomolgus monkeys. We sedated 17 female cynomolgus monkeys (Macaca fascicularis) and measured their vaginal pH by using the three described devices. The results were comparable, and there were no significant difference among the three methods used; however, the color and consistency of the vaginal fluid and the visual acuity of the user did not affect the results measured using the handheld digital pH meter. We conclude that the handheld digital pH meter is a viable method for measuring vaginal pH in cynomolgus monkeys.

The study and optimization of tattoo removal continues to be of importance in the dermatology community. Robust animal models whose skin is physiologically similar to humans and who are easily handled are desirable. To this end, we report on our experience with the hairless guinea pig as a model for tattoo research. This research was conducted as part of a larger study toward increased efficacy of laser tattoo removal. Here we report on procedures for both placement and aftercare of tattoos which result in superior tattoo quality and retention.

Temperature is a valuable parameter used to judge wellness of animals in a research setting; therefore, reliable, noninvasive, and inexpensive methods for monitoring temperature are becoming a necessity in research laboratories. A new method for obtaining temperature in mice, the measurement of body surface temperature via an external probe, was compared to two more common methods, the rectal probe and telemetry. The comparisons of the temperature measuring devices were performed in mice made hypothermic via prolonged anesthesia and in mice made hyperthermic by injection of endotoxin. The results demonstrated good correlation between the surface temperature measurements and the temperatures obtained by both telemetry and the rectal probe. The correlations were particularly significant when core body temperatures were below normal. In addition, the surface probe compared favorably with the other methods with regard to animal stress, observed complications, and initial cost. These results suggest that the surface probe could provide an efficient means for obtaining valuable physiological data and determining humane endpoints.

We developed procedures to foster orphaned African green monkey infants to females with natural infants of a similar age to the foster infant (< 1 month). Our purpose was to assess the feasibility of fostering additional infants to females with natural infants. The subjects were 4 infants (age 1 to 5 days) that were removed from the natural mother because of neglect or trauma. The recipient females varied in parity (0 to 7 previous infants). Within 24 h of removal from the natural mother, the foster infants were presented to a group of potential recipient females by placing the foster infant directly into the cage of the female that demonstrated positive behavior toward the foster infant (reaching toward the infant and lip-smacking). Analysis of the behavioral data collected when the infants were 3 to 6 months of age indicated that foster mothers spent significantly more time nursing the natural infant alone, but the percentage time spent nursing both infants simultaneously was not significantly different than the time spent nursing either infant individually. No significant differences between weaning weight of the natural and foster infants or single infants were observed at 6 months of age. Overall our success rate at weaning (75%) suggests that fostering additional infants on females with a natural infant may be a viable strategy for raising orphaned African green monkeys and may prevent the development of abnormal behaviors that typically are manifested by nursery-reared infants.