Biomechanical comparison between fusion of two vertebrae and implantation of an artificial intervertebral disc

Surgical treatments for lower back pain can be distributed into two main groups: fusion (arthrodesis) and disc replacement (arthroplasty). The objective of this study was to compare, under severe loading conditions, the biomechanics of the lumbar spine treated either by fusion or total disc replacement (TDR). A three-dimensional model of a two-level ligamentous lumbar segment was created and simulated through static analyses with the finite-element method (FEM) software ABAQUS. The model was validated by comparing mobility, pressure on the facets, force in the ligaments, maximum stresses, disc bulge, and endplate deflection with measured data given in the literature. The FEM analysis predicted that the mobility of the model after arthrodesis on the upper level was reduced in all rotational degrees of freedom by an average of approximately 44%, relative to healthy normal discs. Conversely, the mobility of the model after TDR on the upper level was increased in all rotational degrees of freedom by an average of approximately 52%. The level implanted with the artificial disc showed excessive ligament tensions (greater than 500 N), high facet pressures (greater than 3 MPa), and a high risk of instability. The mobility and the stresses in the level adjacent to the arthroplasty were also increased. In conclusion, the model for an implanted movable artificial disc illustrated complications common to spinal arthroplasty and showed greater risk of instability and further degeneration than predicted for the fused model. This modeling technique provides an accurate means for assessing potential biomechanical risks and can be used to improve the design of future artificial intervertebral discs.     

Determination of glucose metabolites in stored erythrocytes and in erythrocytes from patients with thalassemia by analytical isotachophoresis

Glycolysis is for some cells, such as erythrocytes, neutrophil granulocytes and many cancer cells, the only or most important source of energy (ATP) production. Based on previous studies we developed an isotachophoretic (ITP) method which allows, in principle, the simultaneous determination of all metabolites of glycolysis. Since glucose metabolites are small anions, mobility of some of them may overlap in isotachophoresis and, therefore, partial mixed zones are generated. By variation of the leading/terminating system, however, it is possible to separate the compounds of interest. In this communication, we describe a method for analysis of glucose metabolites in erythrocytes from healthy donors during storage in blood bags, and from patients with thalassemia, with special respect to intracellular 2,3 bisphosphoglycerate, lactate and ATP/ADP. The well known characteristic changes of glycolysis in erythrocytes during blood storage and in erythrocytes from thalassemia patients, which are often analysed by separate enzymatic assays, could be confirmed with this isotachophoretic procedure. The method is currently adapted for analysis of glycolysis in neutrophil granulocytes and cancer cells which requires some modifications of sample preparation and performance of the isotachophoretic analysis.     

Borrelia burgdorferi sensu lato infection in mosquitoes from Szczecin area

The aim of the study was to determine the level of infection in mosquitoes with spirochetes Borrelia burgdorferi sensu lato in the woody areas of Szczecin. The mosquitoes were collected from May to September 2003. The spirochetes, Borrelia burgdorferi s. l., present in mosquitoes were detected in mosquitoes with indirect immunofluorescence assay (IFA) using rabbit anti-Borrelia burgdorferi antibodies and goat anti-rabbit IgG marked with fluorescein isocyanate (FITC). A total of 1557 females and 58 males were collected. They represented the genera Aedes (63%) and Culex (37%). The infection level of the mosquitoes from the area studied amounted to 1.7%. The results of the present study confirm the potential of these arthropods to spread Lyme borreliosis.     

Fluoxetine up-regulates expression of cellular FLICE-inhibitory protein and inhibits LPS-induced apoptosis in hippocampus-derived neural stem cell

Fluoxetine is a widely used antidepressant compound which inhibits the reuptake of serotonin in the central nervous system. Recent studies have shown that fluoxetine can promote neurogenesis and improve the survival rate of neurons. However, whether fluoxetine modulates the proliferation or neuroprotection effects of neural stem cells (NSCs) needs to be elucidated. In this study, we demonstrated that 20 microM fluoxetine can increase the cell proliferation of NSCs derived from the hippocampus of adult rats by MTT test. The up-regulated expression of Bcl-2, Bcl-xL and the cellular FLICE-inhibitory protein (c-FLIP) in fluoxetine-treated NSCs was detected by real-time RT-PCR. Our results further showed that fluoxetine protects the lipopolysaccharide-induced apoptosis in NSCs, in part, by activating the expression of c-FLIP. Moreover, c-FLIP induction by fluoxetine requires the activation of the c-FLIP promoter region spanning nucleotides -414 to -133, including CREB and SP1 sites. This effect appeared to involve the phosphatidylinositol-3-kinase-dependent pathway. Furthermore, fluoxetine treatment significantly inhibited the induction of proinflammatory factor IL-1beta, IL-6, and TNF-alpha in the culture medium of LPS-treated NSCs (p<0.01). The results of high performance liquid chromatography coupled to electrochemical detection further confirmed that fluoxentine increased the functional production of serotonin in NSCs. Together, these data demonstrate the specific activation of c-FLIP by fluoxetine and indicate the novel role of fluoxetine for neuroprotection in the treatment of depression.