Infinite horizons impactor

Adult male C57Bl6 mice were utilized in all experiments (20–25 g, Taconic Farms, Derwood, MD). Mice were group housed and received food and water ad libitum with a 12:12 h light cycle. A total of 111 male mice were used for this study; 13 mice were removed from the study due to post-surgical complications. All experiments complied fully with the principles set forth in the “Guide for the Care and Use of Laboratory Animals” and were approved by the Uniformed Services University IACUC.
All subjects undergoing surgery received isoflurane (Primal Healthcare, Andhra Pradesh, India). Mice received a laminectomy, followed by a contusion simulating moderate SCI using the Infinite Horizons Impactor (50 kdyn; Precision Systems and Instrumentation, Fairfax Station, VA). Mice were immediately given an intrathecal injection of either gp91ds-tat or scrambled ds-tat (AnaSpec, Inc., Fremont, CA) diluted to 50 μM in saline in a 5 μl volume at the lesion epicenter. After expelling the liquid, the needle was held under the dura for 30 s prior to removal. The incision was then closed, and animals were maintained on heating pads until mice regained movement. Acetaminophen (Children’s Tylenol, 200 mg/kg) was added to drinking water for 72 h post-injury. Manual bladder expression was performed daily until normal bladder expression returned. Naïve mice did not undergo surgery or receive isoflurane.

Twelve-week male mice (22–25 g) were anesthetized with ketamine/xylazine and a laminectomy was performed in thoracic spinal cord at the level of the T12 vertebra. Contusions were generated applying 75 k-dynes with an Infinite Horizons Impactor (Precision systems and Instrumentation), [16 (link)]. As postoperative care, we administered enrofloxacin (Baytril, Bayer; 2.5 mg/kg, subcutaneously) once daily for 2 weeks. Urine was expelled by manual abdominal pressure twice daily for 1 week and then once daily for the duration of the experiment. The recovery of locomotor performance was evaluated using the Basso Mouse Scale (BMS), as previously described [16 (link)]. Briefly, mice were observed individually for 4 min each in an open field by three investigators blinded to surgery procedures and genotype. Hind limb motor function was recorded and scored according to the BMS guidelines. For statistical analyses we calculated means of left and right hind limb scores for each animal. Catwalk XT Gait Analysis System (Noldus Information Technology, Asheville, NC, USA) was used to assess walk ability of mice. Mice were allowed to freely ambulate along an illuminated glass plate within a confined corridor (L 50 cm × W 8 cm) in a darkened room and footprints were recorded with a high-speed camera for following analyses with CatWalk XT 10.0 software (Noldus).