Recently, numerous types of posterior dynamic stabilization (PDS) devices have been introduced as an alternative to the fusion devices for the surgical treatment of degenerative lumbar spine. It is hypothesized that the use of 'compliant' materials such as Nitinol (Ni-Ti alloy, elastic modulus = 75 GPa) or polyether-etherketone (PEEK, elastic modulus = 3.2 GPa) in PDS can restore stability of the lumbar spine without adverse stress-shielding effects that have often been found with 'rigid' fusion devices made of 'rigid' Ti alloys (elastic modulus = 114 GPa). Previous studies have shown that suitably designed PDS devices made of more compliant material may be able to help retain kinematic behavior of the normal spine with optimal load sharing between the anterior and posterior spinal elements. However, only a few studies on their biomechanical efficacies are available. In this study, we conducted a finite-element (FE) study to investigate changes in load-sharing characteristics of PDS devices. The implanted models were constructed after modifying the previously validated intact model of L3-4 spine. Posterior lumbar fusion with three different types of pedicle screw systems was simulated: a conventional rigid fixation system (Ti6Al4V, Phi = 6.0 mm) and two kinds of PDS devices (one with Nitinol rod with a three-coiled turn manner, Phi = 4.0 mm; the other with PEEK rod with a uniform cylindrical shape, Phi = 6.0 mm). To simulate the load on the lumbar spine in a neutral posture, an axial compressive load (400 N) was applied. Subsequently, the changes in load-sharing characteristics and stresses were investigated. When the compressive load was applied on the implanted models (Nitinol rod, PEEK rod, Ti-alloy rod), the predicted axial compressive loads transmitted through the devices were 141.8 N, 109.8 N and 266.8 N, respectively. Axial forces across the PDS devices (Nitinol rod, PEEK rod) and rigid system (Ti-alloy rod) with facet joints were predicted to take over 41%, 33% and 71% of the applied compression load, respectively. Our results confirmed the hypothesis on the PDS devices by showing the substantial reduction in stress-shielding characteristics. Higher axial load was noted across the anterior structure with the PDS devices, which could slow the degeneration process of bony structures and lower the possibility of implant failure.

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TNF-alpha released from ischemic heart after acute MI increases the production of other cytokines such as interleukin-1 (IL-1), interleukin-6 (IL-6) and adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1). Activation of nuclear factor kappa B (NF-kappa B) by TNF-alpha , up-regulates the expression of molecules which are involved in inflammation and cell adhesion. For these reasons, we assessed the extent that treatment of MSC with tumor necrosis factor (TNF)-alpha modifies the characteristics of MSC, important to their engraftment in experimental myocardial infarct. Here, we show that pre-treatment of MSC prior to transplantation with tumor necrosis factor (TNF)-alpha increases adhesiveness, and migration of MSC in vitro and leads to increased expression of bone morphogenetic protein (BMP)-2 by MSC. Moreover, this treatment increases the rate of engraftment of MSC and improves recovery of cardiac function after myocardial infarction. These insights might provide better strategies for the treatment of myocardial infarction.

In this study, a method of metabolite profiling based on UPLC-QTOF/MS was developed to analyze Platycodon grandiflorum. In the optimal UPLC, various metabolites, including major platycosides, were separated well in 15 min. The metabolite extraction protocols were also optimized by selecting a solvent for use in the study, the ratio of solvent to sample and sonication time. This method was used to profile two different parts of P. grandiflorum, i.e., the roots of P. grandiflorum (PR) and the stems and leaves of P. grandiflorum (PS), in the positive and negative ion modes. As a result, PR and PS showed qualitatively and quantitatively different metabolite profiles. Furthermore, their metabolite compositions differed according to individual plant samples. These results indicate that the UPLC-QTOF/MS-based profiling method is a good tool to analyze various metabolites in P. grandiflorum. This metabolomics approach can also be applied to evaluate the overall quality of P. grandiflorum, as well as to discriminate the cultivars for the medicinal plant industry.

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