Axial Skeletal Malformations in Genetically Modified Xenopus laevis and Xenopus tropicalis.

Skeletal malformations in captive-bred, adult Xenopus spp., have not previously been reported. Here we describe 10 sexually mature, genetically modified laboratory frogs (6 Xenopus laevis and 4 Xenopus tropicalis) with axial skeletal abnormalities. The young adult frogs were described by veterinary staff as presenting with "hunchbacks," but were otherwise considered to be in good health. All affected frogs were genetically engineered using various techniques: transcription activator-like effector nucleases (TALEN) editing using thyroid hormone receptor α TALEN mRNA, restriction enzyme-mediated integration methods involving insertion of the inducible transgene pCAR/TRDN, or via I-SceI meganuclease transgenesis using either pDRTREdpTR-HS4 or pDPCrtTA-TREG-HS4 plasmid sequences. Radiographic findings (6 frogs) and gross necropsy (10 frogs) revealed vertebral column malformations and sacroiliac deformities that resulted in moderate to severe kyphosis and kyphoscoliosis. These findings were confirmed and additional skeletal abnormalities were identified using computed tomography to create a 3D reconstruction of 4 frogs. Additional findings visible on the 3D reconstructions included incomplete vertebral segmentation, malformed transverse processes, and a short and/or curved urostyle. Histopathologic findings included misshapen intervertebral joints with nonconforming articular surfaces, narrowed joint cavities, flattened or irregularly-formed articular cartilage, irregular maturation lines and nonpolarized chondrocytes, excess fibrocartilage, and evidence of irregular bone resorption and growth. While the specific etiology of the vertebral skeletal abnormalities remains unclear, possibilities include: 1) egg/oocyte physical manipulation (dejellying, microinjection, fertilization, etc.), 2) induction and expression of the transgenes, 3) inactivation (knockout) of existing genes by insertional mutagenesis, or 4) a combination of the above. Furthermore, the possibility of undetected changes in the macro or microenvironment, or a feature of the genetic background of the affected frogs cannot be ruled out.

Safety and efficacy of various combinations of injectable anesthetics in BALB/c mice.

Four combinations of drugs--ketamine-xylazine, ketamine-xylazine-acepromazine (KXA), ketamine-xylazine-buprenorphine, and ketamine-xylazine-carprofen--were compared for their ability to produce anesthesia in BALB/c mice. Induction time, anesthetic duration, blood pressure, pulse rate, and time to recovery were recorded. The anesthesia induced by each anesthetic combination was assessed by using reflex responses to standardized stimuli. The KXA combination produced stable physiologic parameters and was associated with the longest duration of anesthesia (40 +/- 8 min); immobility was produced in all other groups (38 +/- 5 min), but a surgical plane of anesthesia could not be confirmed. All anesthetic protocols produced significant hypotension. No deaths occurred. We recommend KXA as a safe and reliable anesthetic for mice requiring a surgical plane of anesthesia.

Comparison of two strategies for diagnosis and treatment of infection in dogs (Canis familiaris) with long-term intravascular catheters.

Exteriorized chronic intravascular catheters (ECICs) are used frequently for repeated substance administration, sampling, and measuring of hemodynamic parameters in biomedical research protocols. ECICs can be a management challenge because they have been associated with catheter occlusion, thrombosis, sepsis, and serious clinical sequela. A monitoring regimen that identified infection early and a treatment protocol that eliminated infection would be of great benefit to animals and to research protocols using ECICs. Using clinical pathology and other parameters, this study compares 2 management strategies in their ability to maintain the physiologic condition of the animals with ECICs. We compared the clinical outcome of treatment initiated in light of an elevated white blood cell count without delay for development of left shift or clinical signs coupled with prolonged duration of treatment (28 d for the first treatment and 42 d for subsequent treatments) with conventional antibiotic treatment initiated after the advent of clinical signs. Significant findings of the study were that the use of fever as an indicator of infection unnecessarily delayed the initiation of treatment by an average of 12 d and that the use of a single clinical pathologic parameter (white blood cell count more than 18,000 cells/ml) as indication for treatment, with or without fever, in addition to prolonged antibiotic treatment (28 d for the first treatment and 42 d for subsequent treatment) initiated as soon as the white blood cell count exceeded 18,000 cells/ml and without delay for development of fever resulted in superior health of the animals with ECICs.