Purpose
of study: The purpose of this study is to evaluate the effect of blow flow originated from transverse process after posterolateral lumbar fusion (PLF) in rabbit.
Materials and Methods
Bilateral PLFs using autogenous iliac bone, 3 mm³ on each operated site, were done in 20 rabbits. In group A, PLFs were done on the decorticated transverse processes. In group B, no decortications were done before PLFs. In group C, PLFs were done after application of Bone wax^® on the transverse processes. In group D, PLFs were done after application of Surgicel^® on the decorticated transverse processes. The five rabbits and 10 operated sites were used in each group. The computed tomography (CT) was done for each group at postoperative 6 and 12 weeks. To evaluate bony union, the status of PLF was divided into ‘union’ and ‘nonunion’ . And, the volumes of grafted bones were counted at each follow up period in each group. The values were analysed statistically.
Results
The union rates of PLFs were observed 90% in group A, 80% in group B, 20% in group C, 70% in group D. Group C showed lowest union rate than other group with statistical signification (p<0.05). The of volumes of grafted bones at postoperative 6 weeks were calculated to 2.8±0.2 mm³ , 2.6±0.3 mm³ , 1.6±0.8 mm³ , 1.8±0.7 mm³ in group A, B, C, D, retrospectively. At postoperative 12 weeks, the volumes were checked as 2.1±0.6 mm³ , 1.8±0.5 mm³ , 1.2±0.9 mm³ , 1.6±0.4 mm³ in group A, B, C, D, retrospectively. The volumes of grafted bones were checked in order to group A, B, D, and C at 6 and 12 weeks postoperatively. And the volumes in group C were mostly reduced at postoperative 6 and 12 weeks (p<0.05). In group C and D, there were statistically significant reduction in volumes of grafted bones at each follow up period comparing to group A and B (p<0.05).
Conclusions
In the PLF of rabbit, the transverse process-grafted bone contact and blood flow originated from transverse process may play major roles in bony union. Among them, the blood flow originated from transverse process might be more important than the bony contact in the union process of PLF.

Purpose
The main purpose of this study was the investigation of the effect of Dexamethasone (DEXA) treatment on TNF-α stimulated intervertebral disc cells through the action mechanism of NF-κB in the cytoplasm and nucleus.
Materials and Methods
We separated cultured human intervertebral disc cells passed three times into four groups. A: control group, B: TNF-α treatment group, C: DEXA treatment group, D: TNF-α and DEXA treatment simultaneously. After extraction of cytoplasmic and nuclear protein from the 4 groups at time points including 10 minutes, 1 hour, and 2 hours, we measured the protein expression levels of p50, p65, p52, and p100 by western blot analysis. Also, we observed the expression of p50, p52, p65 in each group at the 1 hour time point by immunofluorescence analysis.
Results
Western blot analysis demonstrated that cytoplasmic levels of p50 and p65 at1 hour in groups B and D were decreased, groups C showed no significant change as compared to the control group. Nuclear levels of p50 at 1 hour in groups B (10.99 fold) and D (7.24 fold) were increased, and group D had decreased expression compared to group B. Nuclear levels of p50 expression at 2 hours in groups B (12.33 fold) was increased compared to the levels measured at 1 hour. Levels of nuclear p50 in group D at 2 hour time points showed no significant change as compared to the group D at 1 hour time points. In the nucleus, the level of p65 at 1 hour had the same pattern as the p50 expression, however, group B (4.13 fold) and D (4.13 fold) expression levels at 2 hours were decreased compared to the group B (7.49 fold) and D (6.79 fold) at 1 hour. In the cytoplasm, the expression of p100 in groups B and D were decreased after 1hour, and other groups had the same trend as that observed for the control group. Nuclear p100 expression levels were observed in, groups B, C, and D after 2 hours. The cytoplasmic levels of p52 at 10min, 1 hour, and 2 hours were same. The nuclear levels of p52 in group D at 1 hour had no expression and decreased at 2 hours (0.08 fold). The results of the immunofluorescence analysis and the western blot analysis at the 1 hour time point is quite consistent.
Conclusion
Transcriptional mediation of NF-κB was mainly focused on the classical pathway but several protein levels were influenced by the alternative pathway following stimulation with TNF-α in disc cells. The effect of DEXA on NF-κB transcription signaling was observed through the delayed expression of involved proteins and inhibited the translocation of p50, p52, p65 to prevent the expression of corresponding genes.