Vascular Endothelial Growth Factor Enhances Axonal Outgrowth in Organotypic Spinal Cord Slices via Vascular Endothelial Growth Factor Receptor 1 and 2

Enhancing adult nerve regeneration is a potential therapeutic strategy for treating spinal cord injury. Vascular endothelial growth factor (VEGF) is a major contributor to angiogenesis, which can reduce the spinal cord injury by inhibiting the inflammation and improve recovery after spinal cord injury. We have previously demonstrated that exogenous VEGF has neurotrophic effects on injured spinal nerves in organotypic spinal cord slice cultures. However, the mechanisms underlying the neurite growth by exogenous VEGF remain to be explored in spinal cord. In this study, we found out that exogenous VEGF mediated axonal outgrowth through VEGF receptor 1 (VEGFR1) and VEGFR2, both of which were expressed on organotypic spinal cord slices. Although VEGFR1 and VEGFR2 were constitutively expressed in some cells of control spinal cord slices, VEGF treatment upregulated expression of VEGFR1 and VEGFR2. Both VEGFR1 and VEGFR2 were expressed in neuronal cells as well as glial cells of organotypic spinal cord slices. We also observed that VEGF-induced axonal outgrowth was attenuated by a specific mitogen-activated protein kinase (MAPK) inhibitor PD98059 and a specific phosphoinositide 3-kinase (PI3K) inhibitor wortmannin. Thus, these findings suggest that these MAPK and PI3K pathways have important roles in regulating VEGF-induced axonal outgrowth in the postnatal spinal cord.

Effect of repetitive pecking at working length for glide path preparation using G-file

OBJECTIVES: Glide path preparation is recommended to reduce torsional failure of nickel-titanium (NiTi) rotary instruments and to prevent root canal transportation. This study evaluated whether the repetitive insertions of G-files to the working length maintain the apical size as well as provide sufficient lumen as a glide path for subsequent instrumentation. MATERIALS AND METHODS: The G-file system (Micro-Mega) composed of G1 and G2 files for glide path preparation was used with the J-shaped, simulated resin canals. After inserting a G1 file twice, a G2 file was inserted to the working length 1, 4, 7, or 10 times for four each experimental group, respectively (n = 10). Then the canals were cleaned by copious irrigation, and lubricated with a separating gel medium. Canal replicas were made using silicone impression material, and the diameter of the replicas was measured at working length (D0) and 1 mm level (D1) under a scanning electron microscope. Data was analysed by one-way ANOVA and post-hoc tests (p = 0.05). RESULTS: The diameter at D0 level did not show any significant difference between the 1, 2, 4, and 10 times of repetitive pecking insertions of G2 files at working length. However, 10 times of pecking motion with G2 file resulted in significantly larger canal diameter at D1 (p < 0.05). CONCLUSIONS: Under the limitations of this study, the repetitive insertion of a G2 file up to 10 times at working length created an adequate lumen for subsequent apical shaping with other rotary files bigger than International Organization for Standardization (ISO) size 20, without apical transportation at D0 level.

Effect of repetitive pecking at working length for glide path preparation using G-file

OBJECTIVES: Glide path preparation is recommended to reduce torsional failure of nickel-titanium (NiTi) rotary instruments and to prevent root canal transportation. This study evaluated whether the repetitive insertions of G-files to the working length maintain the apical size as well as provide sufficient lumen as a glide path for subsequent instrumentation. MATERIALS AND METHODS: The G-file system (Micro-Mega) composed of G1 and G2 files for glide path preparation was used with the J-shaped, simulated resin canals. After inserting a G1 file twice, a G2 file was inserted to the working length 1, 4, 7, or 10 times for four each experimental group, respectively (n = 10). Then the canals were cleaned by copious irrigation, and lubricated with a separating gel medium. Canal replicas were made using silicone impression material, and the diameter of the replicas was measured at working length (D0) and 1 mm level (D1) under a scanning electron microscope. Data was analysed by one-way ANOVA and post-hoc tests (p = 0.05). RESULTS: The diameter at D0 level did not show any significant difference between the 1, 2, 4, and 10 times of repetitive pecking insertions of G2 files at working length. However, 10 times of pecking motion with G2 file resulted in significantly larger canal diameter at D1 (p < 0.05). CONCLUSIONS: Under the limitations of this study, the repetitive insertion of a G2 file up to 10 times at working length created an adequate lumen for subsequent apical shaping with other rotary files bigger than International Organization for Standardization (ISO) size 20, without apical transportation at D0 level.

The Accuracy of the Accelerometers (Actical and Actigraph) among Korean People

BACKGROUND: Nowadays, decreased physical activity is considered to be a contributor to increase the prevalence of many diseases such as obesity, coronary heart disease and so on. Many researches demonstrated that regular physical activity reduce all cause mortality. To increase the physical activities of the population, accurate estimation of the activities is needed. Actical and actigraph are confirmed as accurate tools to measure physical activities. But the target populations of the validity studies were not Asian people. Therefore, the accuracy of the accelerometers should be confirmed in Asian people. The accuracy of the tools could be different. Therefore head to head comparison study between the tools would be needed. METHODS: Thirty volunteers from the community, ages over 20 yrs, were recruited. The participants put on the two accelerometers (Actical, Actigraph) on the waists, secured with elastic belts, and performed a session of rest and three structured activities (two walking speeds, 4 km/hr and 6 km/hr, and one jogging speed, 8 km/hr). During each activity, expired respiratory gases were collected, and oxygen consumption (VO2) was measured by indirect calorimetry (Model Quark beta2(R)). The calories measured by gas analyzer and two accelerometers were compared by correlation analysis using SPSS program. RESULTS: Pearson correlation coefficient between gas analyzer and two accelerometers was calculated at three structured activities. The r in Actical was 0.747, 0.785, and 0.677, at speed of 4, 6, 8 km/hr, respectively (P<0.05), and the same measures in Actigraph was 0.617, 0.737, and 0.530 (P<0.05), respectively. Pearson correlation coefficient was also calculated between the two accelerometers, and the r was 0.881, 0.927, and 0.824, at each speed. CONCLUSION: The Actical and Actigraph are valid tools for measuring physical activities in Korean people.