The effects of microchipping C57BL/6N mice on standard phenotyping tests.

The C57BL/6N inbred lines of mice are widely used in genetic research. They are particularly favoured in large scale studies such as the International Mouse Phenotyping Consortium (IMPC), where C57BL/6N mice are genetically altered to generate a collection of null alleles (currently more than 8500 null alleles have been generated). In this project, mice carrying null alleles are subjected to a pipeline of broad-based phenotyping tests to produce wide ranging phenotyping data on each model. We have previously described the development of a Home Cage Analysis system that automatically tracks the activity of group housed mice from a microchip inserted in the groin. This platform allows assessment of multiple biologically relevant phenotypes over long periods of time without experimenter interference, and therefore is particularly suited for high through-put studies. To investigate the impact of microchips on other tests carried out in the IMPC pipeline, we inserted microchips in 12 male and 12 female C57BL/6Ntac mice at seven weeks of age. Starting at nine weeks of age these mice underwent standard phenotyping tests, concurrently with 20 unchipped C57BL/6Ntac mice (10 females, 10 males). Tissues from a subset of the microchipped mice (six males and six females), chosen at random, were also sent for histopathological examination at the end of the phenotyping pipeline. No significant impact of insertion of microchip was observed in any of the phenotyping tests apart from bone mineral density measurement at DEXA due to the nature of the microchip. We therefore recommend that the microchip be inserted during the DEXA procedure, after the measurement is taken but before the mouse has recovered from the anaesthetic. This would avoid multiple anaesthetic exposures and prevent the potential variability in DEXA analysis output.

The role of acute decompression and restoration of spinal alignment in the prevention of post-traumatic syringomyelia: case report and review of recent literature.

STUDY DESIGN: Case report. INTRODUCTION: Acute post-traumatic syringomyelia formation after spinal cord injury has been considered a rare complication. At this writing, most recent reports have surfaced in neurosurgical journals. As an entity, post-traumatic syringomyelia has not been widely appreciated. It has been confused with conditions such as Hansen's disease or ulnar nerve compression at the cubital tunnel. One study also demonstrated that the occurrence of syrinx is significantly correlated with spinal stenosis after treatment, and that an inadequate reduction of the spine may lead to the formation of syrinx. This reported case describes a patient in whom post-traumatic syringomyelia began to develop 3 weeks after injury, which improved neurologically after adequate decompression. SUMMARY OF BACKGROUND DATA: A 30-year-old man sustained a 20-foot fall at work. He presented with a complete spinal cord injury below T4 secondary to a T4 fracture dislocation. The patient underwent open reduction and internal fixation of T1-T8. After 3 weeks, the patient was noted to have ascending weakness in his bilateral upper extremities and some clawing of both hands. METHODS: A computed tomography myelogram demonstrated inability of contrast to pass through the T4-T5 region from a lumbar puncture. An incomplete reduction was noted. The canal showed significant stenosis. A magnetic resonance image of the patient's C-spine showed increased signal in the substance of the cord extending into the C1-C2 area. The patient returned to the operating room for T3-T5 decompressive laminectomy and posterolateral decompression including the pedicles, disc, and posterior aspect of the body. Intraoperative ultrasound monitoring showed a good flow of cerebrospinal fluid past the injured segment. RESULTS: On postoperative day 1, the clawing posture of the patient's hands was significantly diminished, and the patient noted an immediate improvement in his hand and arm strength. Over the next few days, the patient's strength in the bilateral upper extremities increased to motor Grade 4/5 on manual testing. A magnetic resonance image 4 weeks after decompression showed significant improvement in the cord diameter and signal. CONCLUSIONS: Post-traumatic syringomyelia has not been reported at so early a stage after injury. This disorder is an important clinical entity that must be recognized to prevent potentially fatal or devastating complications. As evidenced by the reported patient and the literature, if this disorder is discovered and treated early, permanent deficit can be avoided. The prevention of post-traumatic syringomyelia requires anatomic realignment and stabilization of the spine without stenosis, even in the case of complete injuries, to maintain the proper dynamics of cerebrospinal fluid flow.

Prospective, randomized, double-blind study comparing single-agent antibiotic therapy, ciprofloxacin, to combination antibiotic therapy in open fracture wounds.

OBJECTIVE: The purpose of this study was to compare the efficacy of a single agent, ciprofloxacin, with that of combination antibiotic therapy consisting of cefamandole and gentamicin in all types of open fracture wounds. STUDY DESIGN: A prospective double-blind randomized clinical trial. SETTING: A Level 1 trauma center. PATIENTS: One hundred ninety-five consecutive patients with 203 open fractures were enrolled over a twenty-month period. Twenty-nine fractures from low-velocity gunshot wounds were excluded, and three other patients were excluded because of protocol violations. Our final number of patients were 163, with 171 open fractures. MAIN OUTCOME MEASUREMENT: The infection rates for Type I and Type II open fractures for both antibiotic groups were calculated. The infection rate of Type III open fractures for both antibiotic groups was also calculated. Chi-square analysis with Yates correction was used to assess statistical significance of two treatment groups. RESULTS: The infection rate for Types I and II open fractures in the ciprofloxacin group was 5.8 percent and 6 percent for the cefamandole/gentamicin group (p = 1.000). The infection rate for Type III open fractures for the ciprofloxacin group was 31 percent (8 of 26) versus 7.7 percent (2 of 26) for the cefamandole/gentamicin group (p = 0.079). There were no statistically significant differences in infection rate between the group treated with ciprofloxacin and that treated with cefamandole/gentamicin for Types I and II open fracture wounds. However, there appeared to be a high failure rate for the ciprofloxacin Type III open fracture group, with patients being 5.33 times more likely to become infected than those in the combination therapy group. Although this difference was not statistically significant, possibly because of the small sample size, there was a definite trend toward statistical significance. CONCLUSION: Single-agent antibiotic therapy with ciprofloxacin is effective in treatment of Type I and Type II open fracture wounds. However, on the basis of our results, we cannot recommend ciprofloxacin alone for Type III wounds. Possibly one can use fluoroquinolones in combination therapy, specifically as an alternate to an aminoglycoside.