Influence of Ceramic Debris on Osteoblast Behaviors: An In Vivo Study.

OBJECTIVE: Wear-induced aseptic loosening has been accepted as one of the main reasons for failure of total hip arthroplasty. Ceramic wear debris is generated following prosthesis implantation and plays an important part in the upregulation of inflammatory factors in total hip arthroplasty. The present study investigates the influence of ceramic debris on osteoblasts and inflammatory factors. METHODS: Ceramic debris was prepared by mechanical grinding of an aluminum femoral head and added to cultures of MC3T3-E subclone 14 cells at different concentrations (i.e. 0, 5, 10, and 15 µg/mL). Cell proliferation was evaluated using a Cell Counting Kit (CCK-8), and cell differentiation was assessed by mRNA expression of alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). In addition, cell bio-mineralization was evaluated through alizarin red S staining, and release of tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1ß), and interleukin-6 (IL-6) was measured through enzyme-linked immunosorbent assays (ELISA). Furthermore, mRNA expression of Smad1, Smad4, and Smad5 and protein expression of phosphorylated Smad1, Smad4, and Smad5 were measured by reverse transcriptase polymerase chain reaction (RT-PCR) and western blotting. RESULTS: The ceramic debris had irregular shapes and sizes, and analysis of the size distribution using a particle size analyzer indicated that approximately 90% of the ceramic debris was smaller than 3.2 µm (2.0 ± 0.4 µm), which is considered clinically relevant. The results for mRNA expression of ALP, OCN, and OPN and alizarin red S staining indicated that cell differentiation and bio-mineralization were significantly inhibited by the presence of ceramic debris at all tested concentrations (P < 0.05, and the values decreased gradually with the increase of ceramic debris concentration), but the results of the CCK-8 assay showed that cell proliferation was not significantly affected (P > 0.05; there was no significant difference between the groups at 1, 3, and 5 days). In addition, the results of ELISA, RT-PCR, and western blotting demonstrated that ceramic debris significantly promoted the release of inflammatory factors, including TNF-α, IL-ß, and IL-6 (P < 0.05, and the values increased gradually with the increase of ceramic debris concentration), and also greatly reduced the mRNA expression of Smad1, Smad4, and Smad5 (the values decreased gradually with the increase of ceramic debris concentration) as well as protein expression of phosphorylated Smad1, Smad4, and Smad5. CONCLUSION: Ceramic debris may affect differentiation and bio-mineralization of MC3T3-E subclone 14 cells through the bone morphogenetic protein/Smad signaling pathway.

A novel translocator protein 18 kDa ligand, ZBD-2, exerts neuroprotective effects against acute spinal cord injury.

Traumatic spinal cord injury (SCI) happens accidently and often leads to motor dysfunction due to a series of biochemical and pathological events and damage, either temporarily or permanently. Translocator protein 18 (TSPO) has been found to be involved in the synthesis of endogenous neurosteroids which have multiple effects on neurons, but the internal mechanisms are not clear. N-benzyl-N-ethyl-2-(7,8-oxo-2-phenyl-9H-purin-9-yl) acetamide (ZBD-2), a newly reported ligand of TSPO, shows some neuroprotective effect against focal cerebral ischemia in vivo and NMDA-induced neurotoxicity in vitro. The present study aims to examine the role of ZBD-2 in SCI mice and elucidate the underlying molecular mechanisms. The SCI model was established by crushing spinal cord. ZBD-2 (10 mg/kg) significantly enhanced the hindlimb locomotor functions after SCI and decreased the tissue damage and conserved the white matter of the spinal cord. High-dose ZBD-2 alleviated the oxidative stress induced by SCI and regulated the imbalance between NR2B-containing NMDA and GABA receptors by increasing the levels of GAD67 in the spinal cord of SCI mice. Additionally, ZBD-2 (10 mg/kg) increased phosphorylated Akt (p-Akt) and decreased the ratio of Bax/Bcl-2. These results demonstrate that ZBD-2 performs neuroprotection against SCI through regulating the synaptic transmission and the PI3K/AKT signaling pathway.

[The operative treatment of Ruedi II-III Pilon fractures with the ventr-lateral approach].

OBJECTIVE: To investigate the effects of the ventralateral approach in treating severe Pilon fracture. METHODS: From February 2002 to March 2008, 63 patients with Ruedi II-III Pilon fractures were treated with the ventralateral approach, including 36 males and 27 females with an average age of 37 years ranging from 19 to 71 years. The mean time from injury to operation was 8 days (ranged for 2 h-19 d). According to the Ruedi classification system, type II was 32 cases (6 cases of them combined with soft tissue lesion, 4 with open fracture) and type III was 31 cases (9 cases of them combined with soft tissue lesion, 8 with open fracture). The clinical effects were evaluated according to Helfet criteria and the complications were observed including condition of wound healing, infection, bone union, deformity union, motion of the ankle, the degree of the pain and so on. RESULTS: The first intention achieved in 59 cases, the delayed healing in 4 cases. Stiffness of the ankle was found in 5 cases because of bone disunion. All patients were followed up from 8 to 31 months with an average of 15.3 months. The ranging in bone healing time was from 8 to14 weeks with an average of 10 weeks. According to the Helfet criteria, 28 cases obtained excellent results, 30 good, 5 poor. CONCLUSION: The operative treatment of Ruedi I-III Pilon fractures with the ventralateral approach can obtain satisfactory results and avoid complications effectively.

[Proteomic analysis of G2/M arrest of HL-60 cells induced by MG132].

BACKGROUND & OBJECTIVE: Proteasome inhibitor, which can induce apoptosis in various tumor cells, is a kind of potential antitumor drug. This study was to identify the proteins involved in G(2)/M arrest of leukemia cell line HL-60 exposed to proteasome inhibitor MG132 by proteomic techniques. METHODS: Flow cytometry was used to examine cell cycle of HL-60 cells exposed to 2.5 micromol/L MG132. Nuclear extracts of HL-60 cells were prepared, and the purity was detected by light microscopy and Western blot, and the differentially expressed protein spots were determined by two-dimensional gel electrophoresis and identified with MALDI-TOF-TOF/MS. RESULTS: There was a distinct G(2)/M phase arrest before the apoptosis of HL-60 cells induced by 2.5 micromol/L MG132. Twenty-three differentially expressed protein spots were found between MG132-treated and control HL-60 cells; 8 nuclear proteins were identified by MALDI-TOF-TOF/MS analysis. CONCLUSIONS: The detected proteins, such as eIF5A and splicing factor, may be involved in regulation of G(2)/M arrest of HL-60 cells. These findings will be helpful for revealing molecular mechanisms of proteasome inhibitor-induced G(2)/M phase arrest and apoptosis of leukemia cell line.

[Inhibiting expression of human telomerase reverse transcriptase promotes degradation of survivin protein].

BACKGROUND & OBJECTIVE: The expression of Survivin in cancer cells highly correlates with that of human telomerase reverse transcriptase (hTERT). Both of them are ideal targets for cancer gene therapy. This study aimed to clarify if they regulate each other in cancer cells. METHODS: The expressions of Survivin and hTERT in HeLa S3 cells were inhibited by antisense oligonucleotide respectively. Activity of telomerase was detected by telomerase repeat amplification (TRAP) assay. Protein and mRNA levels of Survivin were analyzed by Western blot and reverse transcription-polymerase chain reaction (RT-PCR) respectively. Proliferation of HeLa S3 cells was analyzed by MTT assay. RESULTS: Inhibiting the expression of Survivin in HeLa S3 cells had no effects on telomerase activity. Inhibiting the expression of hTERT by antisense oligonucleotide No.14 decreased protein level of Survivin, which was negatively correlated with the concentration of No.14 (200-1 000 nmol/L), but didn't change mRNA level of survivin. The decrease of Survivin level was inhibited by proteasome inhibitor lactacystin and MG132. Furthermore, simultaneous inhibition of hTERT and survivin co-efficiently inhibited proliferation of HeLa S3 cells. CONCLUSION: Inhibiting the expression of hTERT in HeLa S3 cells promotes ubiquitin-proteasome degradation of Survivin.

[The mechanisms of p21WAF1/Cip-1 expression in MOLT-4 cell line induced by TSA].

To investigate the function and molecular mechanism of p21(WAF1/Cip-1) expression in MOLT-4 cells induced by HDAC inhibitor TSA, the expression pattern of p21(WAF1/Cip-1) and the distribution of cell cycle in TSA treated cells were analyzed. The results showed that TSA could effectively induce G(2)/M arrest and apoptosis of MOLT-4 cells. Kinetic experiments demonstrated that p21(WAF1/Cip-1) were upregulated quickly before cell arrested in G(2)/M and began decreasing at the early stage of apoptosis. Meanwhile, the proteasome inhibitor MG-132 could inhibit the decrease of p21(WAF1/Cip-1) at the early stage of apoptosis, which showed that proteasome pathway involved in p21(WAF1/Cip-1) degradation during the TSA induced G(2)/M arrest and apoptosis responses. This study also identified that the protein level of p21(WAF1/Cip-1) was highly associated with the cell cycle change induced by TSA. Compared to cells treated by TSA only, exposure MOLT-4 cells to TSA meanwhile treatment with MG-132 increased the protein level of p21(WAF1/Cip-1) and increased the numbers of cell in G(2)/M-phase, whereas the cell apoptosis were delayed. It is concluded that p21(WAF1/Cip-1) plays a significant role in G(2)/M arrest and apoptosis signaling induced by TSA in MOLT-4 cells.

[Mechanism of G2/M cell cycle arrest before apoptosis in leukemia cell line HL-60 induced by proteasome inhibitor MG132].

BACKGROUND & OBJECTIVE: Proteasome inhibitor is a kind of potential anti-tumor drug,it can induce apoptosis in various tumor cells. This study was designed to investigate the molecular mechanism of apoptosis and G(2)/M arrest in leukemia cell line HL-60 induced by proteasome inhibitor MG132 (Z-Leu-Leu-Leu-CHO). METHODS: Apoptosis in HL-60 cells was observed under fluorescent microscope, flow cytometry and immunoblot were used to analyze cell apoptosis, cell cycle arrest, and the mechanisms. RESULTS: MG132 (2 micromol/L)induced apoptosis in HL-60 cells after 24-h treatment. Meanwhile, HL-60 cells were arrested at G(2)/M phase before apoptosis after induced by MG132. The percentage of G(2)/M phase in MG132-treated HL-60 cells at 12 h was 63.42+/-2.02,while that in untreated cells was 7.29+/-3.01 (P< 0.01). The percentage of apoptosis in MG132-treated HL-60 cells at 24 h was 16.67+/-1.48, while untreated cells had no death (P< 0.01). Compared to the treatment with MG132 only, caffeine (2 mmol/L) exposure can reduce G(2)/M arrest and apoptosis in MG132-treated HL-60 cells. Expression of cyclin-dependent kinase inhibitor p21waf/cip1 up-regulated after treated with MG132 for 3 h, but no p53 or p27 detected. CONCLUSIONS: Proteasome inhibitor MG132 can induce G2/M arrest before the apoptosis appeared in HL-60 cells. The obvious up-regulation of p21 indicated that it is p21(waf/cip1), but not p53 or p53-related proteins,that involved in the regulation of G(2)/M arrest and subsequent apoptosis induced by MG132 in HL-60 cells.

Expression, Purification and in vitro Activity of Apoptin.

A novel protein named apoptin induces a p53-independent, Bcl-2 insensitive type apoptosis in various human tumor cells but not in normal cells. Apoptin is considered to be a promising candidate for safe and effective anti-tumortherapy. Moreover, apoptin may be important for fundamental studies on molecularbasis of apoptosis and cancer. Apoptin gene was subcloned into prokaryotic expression vector pPROEXHT and pBV220, respectively. The apoptin protein was obtained from pPROEXHT-apoptin expression system and not from pBV220-apoptin the former contains a 6xhistidine affinity tag for ease of purification. Expressed protein was purified by chromatography on a co-chelated affinity column and was renatured by dialysis. The renatured apoptin was able to induce purified Hela nuclei apoptosis in vitro even without the participation of the cytoplasm, showing that apoptin expressed in E.coli was active to induce apoptosis.