Concentrations, seasonal trends, sources, health risk and subchronic toxicity to the respiratory and immune system of PAHs in PM2.5 in Xi'an.

PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) have been proved to be hazardous to health. Previous studies have focused on the distribution and sources of PAHs, whereas there is little knowledge of the damage to organs. Here we sought to investigate the pollution level and seasonal variation characteristics of PAHs in PM2.5 in Xi'an and assess the health risk, to establish a PAHs exposure model, and investigate the toxicological effects of PAHs on the respiratory and immune functions. A sub-chronic exposure model of PAHs was established by inhalation. The pathological changes of lung tissues were observed with a light microscope. Inflammatory reactions in alveolar lavage fluid were determined using the corresponding kit. The levels of interleukin-6 (IL-6) and interleukin-8 (IL-8) were detected with enzyme linked immunosorbent assay (ELISA) kit; the proliferation of lymphocytes in spleen was detected with methyl tetrazolium (MTT); DNA immune damage was determined with DNA gel electrophoresis. The results showed that (1) the total concentration of 16 PAHs ranged from 41.1 to 387 ng/m3, with a mean value of 170 ng/m3, and the concentration of PAHs in PM2.5 was higher in winter than in other seasons. (2) The sources of PAHs in the atmosphere of Xi'an urban area were mainly coal combustion, and the equivalent carcinogenic concentration of PAHs in PM2.5 was 3.9 ng/m3. (3) Foreign body granuloma formation and inflammatory cell damage were observed in the lungs of rats infected with toxin; the levels of reactive oxygen species (ROS) and mobile device assistant (MDA) increased while nitric oxide synthase (NOS) decreased with the increase of dose; the expression levels of IL-6 and IL-8 elevated with the increase of toxin dose, showing an obvious dose-effect relationship; the level of PAHs damage to cells showed a dose-effect relationship. Sub-chronic exposure to PAHs could cause sustained inflammatory injury to the organism. Measures should be taken to counter the problems of PAHs in PM2.5 in Xi'an and relevant health promotion strategies should be developed.

Chrysin suppressed inflammatory responses and the inducible nitric oxide synthase pathway after spinal cord injury in rats.

Chrysin (CH), a natural plant flavonoid, has shown a variety of beneficial effects. Our present study was conducted to evaluate the therapeutic potential of CH three days after spinal cord injury (SCI) in rats and to probe the underlying neuroprotective mechanisms. SCI was induced using the modified weight-drop method in Wistar rats. Then, they were treated with saline or CH by doses of 30 and 100 mg/kg for 26 days. Neuronal function was assessed with the Basso Beattle Bresnahan locomotor rating scale (BBB). The water content of spinal cord was determined after traumatic SCI. The NF-κB p65 unit, TNF-α, IL-1ß and IL-6 in serums, as well as the apoptotic marker, caspase-3, of spinal cord tissues were measured using commercial kits. The protein level and activity of inducible nitric oxide synthase (iNOS) were detected by western blot and a commercial kit, respectively. NO (nitric oxide) production was evaluated by the determination of nitrite concentration. The rats with SCI showed marked reductions in BBB scores, coupled with increases in the water content of spinal cord, the NF-κB p65 unit, TNF-α, IL-1ß, IL-6, iNOS, NO production and caspase-3. However, a CH supplement dramatically promoted the recovery of neuronal function and suppressed the inflammatory factors, as well as the iNOS pathway in rats with SCI. Our findings disclose that CH improved neural function after SCI in rats, which might be linked with suppressing inflammation and the iNOS pathway.

Effect of one versus two distal locking bolts on the biomechanics of tibial interlocking nail: a comparative study using a new model.

OBJECTIVE: To investigate the impact of one versus two distal locking bolts on the mechanical properties of tibial interlocking intramedullary nails. METHODS: Twenty 9-mm titanium alloy locking nails were divided into two equal groups in which the nails were fixed with only one and two distal locking bolts, respectively. Each group was further divided into two sub-groups for compression and torsion tests separately using a universal material-testing machine. RESULTS: In the compression tests, the average maximum strength of double bolts was greater than that of the single bolt (P<0.05), but the number of the bolts did not significantly affect the results of the torsion tests in terms of the either the maximum torsion moment or angle (P>0.05). CONCLUSION: One distal bolt is sufficient for fixing stable fractures and double bolts are recommended for management of serious fractures. The model we used is convenient and economic for examining the biomechanics of the tibial nails, especially for comparative purposes.

Selection of femoral prosthesis in total hip replacement for ankylosing spondylitis.

OBJECTIVE: To investigate the implication of morphological changes of the proximal femur in femoral prosthesis selection in total hip replacement for treatment of ankylosing spondylitis (AS). METHODS: Twenty-four patients (36 hips) admitted for cementless total hip replacement (THR) because of AS were enrolled in this study along with the control group of 30 patients (45 hips) without AS. Measurement of the Singh index, canal flare index, morphological index of the cortex, cortical index and stem-canal fit was performed in the two groups on the basis of roentgenograms. RESULTS: The AS patients had more serious osteoporosis in their proximal femur. There were significant differences between the two groups in Singh index, canal flare index, morphological index of the cortex and stem-canal fit (P<0.05), but not in the cortical index (P>0.05). The AS patients were found to have severe osteoporosis in the upper femur and massive spongy bone loss, so that the morphology of the canal was almost orthostatic in the upper femur because of the thinned femoral cortex. CONCLUSION: Cemented prosthesis is recommended for AS patients with severe osteoporosis, who should be treated with revised THR to ensure good fit of the prosthesis to the canal. Cementless prosthesis, however, can still achieve good therapeutic effect in AS patients without significant morphologic changes in the proximal femurs. Computer-aided design and manufacture of individualized prosthesis better suits the AS patients than the currently available prosthesis.

Prokaryotic expression, purification and activity assay of recombinant vascular endothelial growth factor.

OBJECTIVE: To express human vascular endothelial growth factor (hVEGF(165)) in E. coli JM109 in the form of fusion protein by genetic engineering and test the biological activity and immunological competence of the expressed protein. METHODS: hVEGF(165) gene was subcloned by PCR and inserted into pQE30 plasmid. hVEGF(165) fusion protein was expressed in E. coli JM109 and purified by Ni(2+)-NTA. The immunological competence of the expressed protein was tested by means of Western blotting and enzyme-linked immunosorbent assay (ELISA), and its biological activity was assayed by chicken chorioallantoic membrane (CAM) and Matrigel angiogenesis assay. RESULTS: The recombinant hVEGF(165) fusion protein was successfully expressed in E. coli JM109 and its expression accounted for 30% of the total cellular protein. The purified protein presented a single band of 23 kD in SDS-PAGE. Western blotting, ELISA, CAM and matrigel angiogenesis assay showed excellent immunologic competence and biological activity of the recombinant protein. CONCLUSION: Recombinant hVEGF(165) protein with excellent biological activity has been successfully expressed in E.coli JM109, which may facilitate future study in construction of prefabricated tissue-engineered bone graft.