؊ by superoxide dismutase and inhibition of ERK activation by PD98059 decreased specific osteogenic transcription factor, core binding factor A1 activation, and decreased osteocalcin expression. Taken together, we showed that ESW-induced O 2 ؊ production followed by tyrosine kinase-mediated ERK activation and core binding factor A1 activation resulted in osteogenic cell growth and maturation. Thus, an appropriate modulation of redox reaction by ESW may have some positive effect on the bone regeneration.Oxidative stress induced by superoxide has been implicated in the induction of certain cell injury (1-5). In contrast, superoxide also plays an important role in the regulation of cell proliferation and metabolism (6 -8). Several physical factors such as heat (9), electrical field (10), pulsatile stretch (11), and laser irradiation (12) can stimulate cell proliferation through the involvement of superoxide. It is not known whether superoxide can regulate osteoprogenitor cell growth and differentiation.Extracorporeal shock wave (ESW) 1 is created by a high voltage spark discharge under water causing an explosive evaporation of water and producing high energy acoustic waves. The acoustic waves are focused on a semi-ellipsoid reflector and therefore can be transmitted into a specific tissue site (13). ESW treatment has been divergently applied for eukaryotic and prokaryotic biology systems. It is well known that ESW provides a non-invasive biophysical strategy for breaking renal stones with minimal side effects (13). Evidence also suggests that shock waves can potentially enhance gene transfer (14), suppress tumor growth (15), and promote the bactericidal effect of microorganisms (16).Recently, we and others (17)(18)(19)(20) have shown that ESW treatment has a promising effect on the promotion of bone fracture healing and repair of tendinitis. The mechanism by which ESW enhances fracture healing and repair of tendinitis remains to be determined. The fact that ESW treatment enhances both bone and tendon regeneration suggests that ESW may induce a certain signal for growth and maturation of the mesenchymal progenitors from bone marrow. It has been well clarified that the differentiation and maturation of bone marrow mesenchymal osteoprogenitor cells into osteoblastic lineage is involved in bone regeneration (21)(22)(23). In support of the hypothesis, we have recently shown ESW treatment to be able to promote bone marrow stromal cell growth and differentiation toward osteogenic lineage, presumably through TGF-␤1 induction (24).Accumulated evidence suggests that ESW induces a cavitation effect to increase membrane permeability and the influx of biological substances (25,26), which are usually implicated in cell and tissue damage (15,27). There is limited evidence showing that ESW promotes cell growth rather than cell damage. We hypothesized in this study that an optimal ESW treatment promoted osteoprogenitor cell growth and maturation via a rapid induction of oxygen radicals for a signal transduction

This 12-year-old boy illustrated the rapid spontaneous resolution of traumatic subdural hematoma in both left hemisphere and lumbar spine with conservative treatment. This report suggests a possible role of conservative management for traumatic lumbar subdural hematoma, especially when the patients already have neurologic recovery.

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