Degenerative changes of the canine cervical spine after discectomy procedures, an in vivo study.

BACKGROUND: Discectomies are a common surgical treatment for disc herniations in the canine spine. However, the effect of these procedures on intervertebral disc tissue is not fully understood. The objective of this study was to assess degenerative changes of cervical spinal segments undergoing discectomy procedures, in vivo. RESULTS: Discectomies led to a 60% drop in disc height and 24% drop in foraminal height. Segments did not fuse but showed osteophyte formation as well as endplate sclerosis. MR imaging revealed terminal degenerative changes with collapse of the disc space and loss of T2 signal intensity. The endplates showed degenerative type II Modic changes. Quantitative MR imaging revealed that over 95% of Nucleus Pulposus tissue was extracted and that the nuclear as well as overall disc hydration significantly decreased. Histology confirmed terminal degenerative changes with loss of NP tissue, loss of Annulus Fibrosus organization and loss of cartilage endplate tissue. The bony endplate displayed sclerotic changes. CONCLUSION: Discectomies lead to terminal degenerative changes. Therefore, these procedures should be indicated with caution specifically when performed for prophylactic purposes.

Medical infrared imaging (thermography) of type I thoracolumbar disk disease in chondrodystrophic dogs.

OBJECTIVE: To: (1) determine the success of medical infrared imaging (MII) in identifying dogs with TLIVDD, (2) compare MII localization with magnetic resonance imaging (MRI) results and surgical findings, and (3) determine if the MII pattern returns to that of normal dogs 10 weeks after decompression surgery. STUDY DESIGN: Prospective case series. ANIMALS: Chondrodystrophic dogs (n = 58) with Type I TLIVDD and 14 chondrodystrophic dogs with no evidence of TLIVDD. METHODS: Complete neurologic examination, MII, and MRI studies were performed on all dogs. Dogs with type I TLIVDD had decompressive surgery and follow-up MII was performed at 10 weeks. Pattern analysis software was used to differentiate between clinical and control dogs, and statistical analysis using anatomic regions of interest on the dorsal views were used to determine lesion location. Recheck MII results were compared with control and pre-surgical images. RESULTS: Computer recognition pattern analysis was 90% successful in differentiating normal dogs from dogs affected by TLIVDD and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD. Statistical comparisons of the ROI mean temperature were unable to determine the location of the disc herniation. Recheck MII patterns did not normalize and more closely resembled the clinical group. CONCLUSIONS: MII was 90% successful differentiating between normal dogs and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD. Abnormal intervertebral disc space localization using ROI mean temperature analysis was not successful. MII patterns 10 weeks after surgery do not normalize.

Mouse A6-positive hepatic oval cells also express several hematopoietic stem cell markers.

Hepatic oval cells (HOC) are thought to be a type of facultative stem cell that arises as a result of certain forms of hepatic injury. A new and more efficient model has been established to activate the oval cell compartment in mice by incorporating 3,5-diethoxycarbonyl-1,4-dihydro-collidine (DDC) in a standard chow at a concentration of 0.1%. At the present time, very few markers exist for the mouse oval cells. One accepted marker is A6, an uncharacterized epitope recognized by mouse hepatic oval cells and it is accepted to be an oval cell marker. Sca-1 is a cell surface marker used to identify hematopoietic stem cells in conjunction with Thy-1+, CD34+, and lineage-specific markers. Both the CD34 and Sca-1 antigens are not normally expressed in adult liver, but are expressed in fetal liver, presumably on the hematopoietic cells. We report herein that mouse oval cells express high levels of Sca-1 and CD34, as well as CD45 surface proteins. Immunohistochemistry revealed that the cells expressing Sca-1/CD34/CD45 were indeed oval cells because they co-expressed the oval cell-specific marker A6 (94.57% +/- 0.033%), as well as alpha-fetoprotein (AFP) (75.92% +/- 0.071%). By using Sca-1 antibody in conjunction with magnetic activated cell sorting (MACS), followed with a flow cytometric cell sorting (FACS) method for CD34 and CD45, we have developed a rapid oval cell isolation protocol with high yields of greater than 90%. In conclusion, we have an efficient murine model for the production and isolation of large numbers of highly purified oval cells. Our system works with most strains of mouse, which will facilitate both in vivo and in vitro studies of mouse hepatic oval cells.