Effect of nesting material on body weights of mice infected with Toxoplasma gondii.

Toxoplasmosis, a disease caused by the parasitic protozoan Toxoplasma gondii, can cause a number of clinical signs in mice, including weight loss. This weight loss likely is related to the host immune response and is important to monitor in Toxoplasma studies. Several studies have demonstrated that nesting material can affect body weights of mice. We therefore sought to assess the effects of nesting material on body weights of mice infected with Toxoplasma. We housed mice with or without nesting material and weighed and clinically assessed them twice weekly for 30 days prior to and 5 wk after Toxoplasma inoculation. Nesting material did not significantly alter the weights of mice after Toxoplasma inoculation but did decrease rates of growth prior to inoculation. Nesting material did not affect the clinical outcome of Toxoplasma infections, supporting the provision of nesting material in mouse Toxoplasma experiments.

Effective and safe anesthesia for Yorkshire and Yucatan swine with and without cardiovascular injury and intervention.

The goal of this study was to identify an injectable anesthetic protocol that provides sedation sufficient for peripheral vascular catheterization, intubation, and transport while minimizing cardiovascular changes in Yorkshire and Yucatan pigs with and without cardiovascular injury and intervention (CI). Phase 1 examined the safety and efficacy of acepromazine-ketamine, diazepam-ketamine, midazolam-ketamine, and medetomidine-ketamine in 5 healthy Yorkshire pigs. For each drug combination, we obtained multiple measurements of heart rate, blood pressure, respiratory rate, temperature, sedation score, ability to catheterize and intubate, and recovery score. Phase 2 evaluated and refined the dose of the most effective Phase 1 anesthetic combination (midazolam-ketamine) in healthy and CI Yorkshire pigs (n = 53 trials). Phase 3 mirrored Phase 2 but tested midazolam-ketamine in healthy and CI Yucatan pigs (n = 34 trials). Midazolam (0.5 mg/kg)-ketamine (25 to 27 mg/kg) was the most effective anesthetic combination in healthy Yorkshire pigs, but this dose was less effective in healthy Yucatan pigs and CI Yorkshire and Yucatan pigs. Midazolam-ketamine resulted in tachycardia and apnea more frequently in CI pigs than healthy pigs. This combination also caused vomiting in one CI Yucatan pig. Overall, midazolam-ketamine provided safe and effective sedation for catheterization and intubation of both healthy and CI pigs. This study suggests Yucatan pigs may require a higher dose midazolam-ketamine to achieve the same level of sedation as that in Yorkshire pigs. Although anesthetic complication rates were higher in CI pigs, our results indicate that midazolam-ketamine can be safely used for sedation of both pig breeds with and without CI.

Evaluation of the role of constitutive isocitrate lyase activity in Yersinia pestis infection of the flea vector and mammalian host.

Yersinia pestis, unlike the closely related Yersinia pseudotuberculosis, constitutively produces isocitrate lyase (ICL). Here we show that the Y. pestis aceA homologue encodes ICL and is required for growth on acetate but not for flea infection or virulence in mice. Thus, deregulation of the glyoxylate pathway does not underlie the recent adaptation of Y. pestis to arthropod-borne transmission.