51
|
Du C, Li H, Cao G, Xilingaowa, Wang C, Li C. Expression of the Orexigenic Peptide Ghrelin and the Type 1a Growth Hormone Secretagogue Receptor in Sheep Oocytes and Pre-implantation Embryos ProducedIn Vitro. Reprod Domest Anim 2010; 45:92-8. [DOI: 10.1111/j.1439-0531.2008.01259.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
52
|
Gong Y, Du C, Josephson D, Wilson T, Nelson R. POD-06.09: Robotic Partial Nephrectomy for Complex Renal Cell Carcinoma. Urology 2009. [DOI: 10.1016/j.urology.2009.07.1160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
53
|
Du C, Campbell G, Misailidis N, Mateos-Salvador F, Sadhukhan J, Mustafa M, Weightman R. Evaluating the feasibility of commercial arabinoxylan production in the context of a wheat biorefinery principally producing ethanol. Part 1. Experimental studies of arabinoxylan extraction from wheat bran. Chem Eng Res Des 2009. [DOI: 10.1016/j.cherd.2008.12.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
54
|
Misailidis N, Campbell G, Du C, Sadhukhan J, Mustafa M, Mateos-Salvador F, Weightman R. Evaluating the feasibility of commercial arabinoxylan production in the context of a wheat biorefinery principally producing ethanol. Chem Eng Res Des 2009. [DOI: 10.1016/j.cherd.2008.12.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
55
|
Sun Z, Fan D, Fan Y, Du C, Moradian-Oldak J. Enamel proteases reduce amelogenin-apatite binding. J Dent Res 2009; 87:1133-7. [PMID: 19029081 DOI: 10.1177/154405910808701212] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Organic matrix degradation and crystal maturation are extracellular events that occur simultaneously during enamel biomineralization. We hypothesized that enamel proteases control amelogenin-mineral interaction, which, in turn can affect crystal nucleation, organization, and growth. We used a recombinant amelogenin (rP172), a homolog of its major cleavage product (rP148), and a native amelogenin lacking both N- and C-termini (13k). We compared apatite binding affinity between amelogenins and their digest products during proteolysis. We further compared binding affinity among the 3 amelogenins using a Langmuir model for protein adsorption. Amelogenin-apatite binding affinity was progressively reduced with the proteolysis at the C- and N- termini by recombinant pig MMP-20 (rpMMP20) and recombinant human kallikrein-4 (rhKLK4), respectively. The binding affinity of amelogenin to apatite was found to be in the descending order of rP172, rP148, and 13k. Analysis of our data suggests that, before its complete degradation during enamel maturation, stepwise processing of amelogenin by MMP-20 and then KLK4 reduces amelogenin-apatite interaction.
Collapse
|
56
|
Lopatto D, Alvarez C, Barnard D, Chandrasekaran C, Chung HM, Du C, Eckdahl T, Goodman AL, Hauser C, Jones CJ, Kopp OR, Kuleck GA, McNeil G, Morris R, Myka JL, Nagengast A, Overvoorde PJ, Poet JL, Reed K, Regisford G, Revie D, Rosenwald A, Saville K, Shaw M, Skuse GR, Smith C, Smith M, Spratt M, Stamm J, Thompson JS, Wilson BA, Witkowski C, Youngblom J, Leung W, Shaffer CD, Buhler J, Mardis E, Elgin SCR. Undergraduate research. Genomics Education Partnership. Science 2008. [PMID: 18974335 DOI: 10.1126/science.1165351.under] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The Genomics Education Partnership offers an inclusive model for undergraduate research experiences incorporated into the academic year science curriculum, with students pooling their work to contribute to international data bases.
Collapse
|
57
|
Lopatto D, Alvarez C, Barnard D, Chandrasekaran C, Chung HM, Du C, Eckdahl T, Goodman AL, Hauser C, Jones CJ, Kopp OR, Kuleck GA, McNeil G, Morris R, Myka JL, Nagengast A, Overvoorde PJ, Poet JL, Reed K, Regisford G, Revie D, Rosenwald A, Saville K, Shaw M, Skuse GR, Smith C, Smith M, Spratt M, Stamm J, Thompson JS, Wilson BA, Witkowski C, Youngblom J, Leung W, Shaffer CD, Buhler J, Mardis E, Elgin SCR. Undergraduate research. Genomics Education Partnership. Science 2008; 322:684-5. [PMID: 18974335 PMCID: PMC2953277 DOI: 10.1126/science.1165351] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Genomics Education Partnership offers an inclusive model for undergraduate research experiences incorporated into the academic year science curriculum, with students pooling their work to contribute to international data bases.
Collapse
|
58
|
Shi Y, Du C, Zhou Y. Efficacy and safety of the imatinib in the treatment of 73 gastrointestinal stromal tumors. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.21512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
59
|
Sadhukhan J, Mustafa M, Misailidis N, Mateos-Salvador F, Du C, Campbell G. Value analysis tool for feasibility studies of biorefineries integrated with value added production. Chem Eng Sci 2008. [DOI: 10.1016/j.ces.2007.09.039] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
60
|
Zhou Y, Du C, Fu H, Zhao G, Shi Y. Multivisceral resections of gastrointestinal stromal tumors. J Clin Oncol 2007. [DOI: 10.1200/jco.2007.25.18_suppl.20523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
20523 Background: Gastrointestinal stromal tumors (GISTs) with positive kit staining, although rare, are the most common mesenchymal neoplasms affecting the gastrointestinal tract. We present our experience in the treatment of disease involving adjacent organs with multivisceral resections. Methods: The clinicopathologic records of twenty-two patients with multivisceral resection, among 170 patients suffered from GISTs treated in our hospital from 1994 to 2005, were retrospectively reviewed. Nine primary tumors originated from the stomach, 4 from the small intestine, 6 from the colorectum, 1 from abdominal cavity, and 2 from the retroperitoneal area. Meanwhile complete follow-up records were available in 15 patients with median 5-year follow-up. Results: The patients included 9 men and 13 women, from 36 to 77 year old. The largest tumor diameter ranged from 2 to 20 cm. The types of multivisceral operation comprised splenectomy (n=8), coloectomy (n=6), nephrectomy (n=5), partial hepatectomy (n=1), duodenectomy (n=1), oophorectomy (n=1), pancreatectomy (n=1), and adrenalectomy (n=1). None of lymph node metastatsis was found in 7 patients with lymph node dissection with gastric GISTs (n=5) or small intestinal GISTs (n=2). The involved organs confirmed by the pathologic diagnosis included kidney (n=2), spleen (n=2), pancreas (n=2), mesentery (n=1), and omentum (n=1). There was no perioperative mortality in this series. Among follow up patients, 9 were alive and 5 were died from the tumor recurrence or metastasis. Among them, one person with gastrectomy, pancreatectomy, adrenalectomy is still alive under 2 year follow-up by imatinib mesylate therapy postoperatively. Conclusions: Complete surgical resection with a negative gross margin by en bloc resection of the involved organs remains the standard treatment for non-metastatic GISTs. Imatinib mesylate represents a major breakthrough in the treatment of advanced GISTs and is the first effective systemic therapy for the disease. No significant financial relationships to disclose.
Collapse
|
61
|
Abstract
20534 Objective: To investigate the prognostic factor of gastrointestinal stromal tumor. Methods: The clinicopathological data of 103 patients with gastrointestinal stromal tumors were analyzed restrospectively. Life table, kaplan-meier survival rate and cox regression model were used to evaluate the prognostic factors. Results: The 1 year ,3 years and 5 years total survival rate of these 103 gastrointestinal stromal tumors was 86.3%, 51.7%, 42.8%. Tumor size, mitotic rate, primary organ of tumor and radical surgical excision or not were analyzed respectively, the difference is statistical significance (P<0.05). No significiant difference between the group of sex, age, immunohistochemistry expression and multi-organ resection or not. Conclusion: Flechers’ classification is rational, scientific, simple and feasible. Radical surgical excision is the best therapy to the primary gastrointestinal stomal tumor. No significant financial relationships to disclose.
Collapse
|
62
|
Du C, Jiang J, Guan Q, Diao H, Yin Z, Wang S, Zhong R, Jevnikar AM. NOS2 (iNOS) deficiency in kidney donor accelerates allograft loss in a murine model. Am J Transplant 2007; 7:17-26. [PMID: 17061993 DOI: 10.1111/j.1600-6143.2006.01558.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Renal NOS2 is expressed and produces abundant nitric oxide (NO) in various renal cells in response to proinflammatory cytokines. However, the role of this enzyme in renal allograft survival remains unknown. Kidney allotransplantation was performed in the murine model of C57BL/6J (H-2(d)) to nephrectomized Balb/c (H-2(b)) mice. Here we show that deficiency in NOS2 expression in kidney donors significantly advanced allograft failure, indicated by decreasing mean survival of recipients receiving NOS2 null grafts (15.4 +/- 6.4 days) as compared to those with wild type grafts (65.4 +/- 28.1 days) (p = 0.0005). Consistent with survival results, NOS2 null grafts had more severe renal tubule injury and decreased renal function compared to wild type grafts. In vitro NOS2 expressing TEC had greater resistance to allogeneic lymphocyte-mediated apoptosis. The addition of exogenous NO inhibited Fas-mediated TEC apoptosis and reduced proliferation of allogeneic lymphocytes. These data suggest that endogenous production of NO through renal NOS2 activity can play a protective role in kidney grafts through attenuating Fas-mediated donor cell apoptosis as well as by inhibiting proliferation of inflammatory infiltrating lymphocytes. Enhanced donor NOS2 expression may be a useful strategy to improve kidney transplant survival.
Collapse
|
63
|
Du C, Wang S, Diao H, Guan Q, Zhong R, Jevnikar AM. Increasing resistance of tubular epithelial cells to apoptosis by shRNA therapy ameliorates renal ischemia-reperfusion injury. Am J Transplant 2006; 6:2256-67. [PMID: 16970799 DOI: 10.1111/j.1600-6143.2006.01478.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Renal tubular epithelial cells (TEC) die by apoptosis or necrosis in renal ischemia-reperfusion injury (IRI). Fas/Fas ligand-dependent fratricide is critical in TEC apoptosis, and Fas promotes renal IRI. Therefore, targeting Fas or caspase-8 may have therapeutic potential for renal injury in kidney transplant or failure. RNA silencing by short hairpin RNA (shRNA) is a novel strategy to down-regulate protein expression. Using this approach, silencing of Fas or caspase-8 by shRNA to prevent TEC apoptosis and IRI was evaluated. IRI was induced by renal artery clamping for 45 or 60 min at 32 degrees C in uninephrectomized C57BL/6 mice. Here, we showed that Fas or pro-caspase-8 expression was significantly knocked down in TEC by stable expression of shRNA, resulting in resistance to apoptosis induced by superoxide, IFN-gamma/TNF-alpha and anti-Fas antibody. Inferior vena cava delivery of pHEX-small interfering RNA targeting Fas or pro-caspase-8 resulted in protection of kidney from IRI, indicated by reduction of renal tubular injury (necrosis and apoptosis) and serum creatinine or blood urea nitrogen. Our data suggest that shRNA-based therapy targeting Fas and caspase-8 in renal cells can lead to protection of kidney from IRI. Attenuation of pro-apoptotic proteins using genetic manipulation strategies such as shRNA might represent a novel strategy to promote kidney allograft survival from rejection or failure.
Collapse
|
64
|
Falini G, Fermani S, Du C, Moradian Oldak J. The organization of the organic structural framework in the enamel biomineralization processes. Acta Crystallogr A 2006. [DOI: 10.1107/s0108767306099193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
65
|
|
66
|
Young JC, Wu S, Hansteen G, Du C, Sambucetti L, Remiszewski S, O'Farrell AM, Hill B, Lavau C, Murray LJ. Inhibitors of histone deacetylases promote hematopoietic stem cell self-renewal. Cytotherapy 2006; 6:328-36. [PMID: 16146885 DOI: 10.1080/14653240410004899] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Histone deacetylases (HDAC) are associated with a variety of transcriptional repressors that control cellular differentiation and proliferation. HDAC inhibitors such as trichostatin A, trapoxin and chlamydocin could be useful tools to modulate these cellular processes. We investigated their effect on the self-renewal of hematopoietic stem cells (HSC) during ex vivo culture. METHODS Purified murine HSC with the phenotype c-Kit+,Thy-1.1(lo), Lin(-/lo), Sca-1+ were cultured for 4 days with IL-3, IL-6 and c-Kit ligand without or with HDAC inhibitors, after which their degree of phenotypic differentiation in culture was assessed by flow cytometric analysis. To explore whether HDAC inhibitors could have a beneficial role in human HSC transplantation, mobilized peripheral blood CD34+ cells were cultured with thrombopoietin mimetic peptide, flt3 ligand, and c-Kit ligand, without or with various HDAC inhibitors. The fluorescent dye, carboxyfluorescein-diacetate succinimidylester (CFSE), was used to track division of cell subsets, and engrafting ability was evaluated in a non-obese diabetic (NOD) -SCID xenotransplantation model. RESULTS Murine HSC cultured with HDAC inhibitors maintained a more primitive phenotype than control cultures. The number of human HSC expressing Thy-1 increased up to seven-fold during a 5-day culture with HDAC inhibitors compared with control cultures. Chlamydocin was the most effective of the HDAC inhibitors tested at promoting Thy-1 expression on human cells. CFSE tracking showed that the increase in Thy-1+ cells resulted from cell division. In a NOD-SCID repopulation assay, cells exposed to chlamydocin for 24 h displayed an average four-fold higher engrafting ability over control cells. DISCUSSION Our studies suggest that HDAC inhibitors can induce ex vivo expansion of human HSC, and may improve engraftment in hematopoietic transplant patients when cell dose is limiting.
Collapse
|
67
|
Du C, Schneider GB, Zaharias R, Abbott C, Seabold D, Stanford C, Moradian-Oldak J. Apatite/amelogenin coating on titanium promotes osteogenic gene expression. J Dent Res 2005; 84:1070-4. [PMID: 16246944 DOI: 10.1177/154405910508401120] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Osteoblast differentiation and extracellular matrix production are pivotal processes for implant osseointegration or bone tissue engineering. We hypothesized that a biomimetic coating on titanium surfaces, consisting of apatite and amelogenin, would promote such processes. Human Embryonic Palatal Mesenchymal pre-osteoblasts were used as a model for the evaluation of cell adhesion and spreading patterns, as well as mRNA expression of certain osteoblastic gene products. Real-time PCR showed significant (p < 0.05) increase in expression of type I collagen, alkaline phosphatase, and osteocalcin from cells grown on titanium with an apatite/amelogenin composite, as compared with that from cells grown on a pure titanium or apatite coating only. Osteocalcin expression was specifically stimulated by amelogenin added to the culture media. Enhanced attachment and cell spreading were also observed. The biomimetic coating promoting cell adhesion and osteoblast differentiation may have great potential for future dental and biomedical applications.
Collapse
|
68
|
Falini G, Fermani S, Du C, Moradian-Oldak J. The organization of the organic structural framework in the enamel biomineralization processes. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305097114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
69
|
Du C, Tang MT, Lee YR, Stetsko YP, Lo CY, Lee JJ, Lin HH, Chang SL. Dynamic phase transition of the charge-density wave lattice. Acta Crystallogr A 2005. [DOI: 10.1107/s0108767305086307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
70
|
Saunders MM, Taylor AF, Du C, Zhou Z, Pellegrini VD, Donahue HJ. Mechanical stimulation effects on functional end effectors in osteoblastic MG-63 cells. J Biomech 2005; 39:1419-27. [PMID: 15953606 DOI: 10.1016/j.jbiomech.2005.04.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Accepted: 04/08/2005] [Indexed: 10/25/2022]
Abstract
Receptor activator of Nf-kappaB ligand (RANKL) and osteoprotegerin (OPG) have been implicated in bone metabolism. Specifically, the balance of these factors in conjunction with receptor activator of Nf-kappaB (RANK) is believed to be key in determining the rate of osteoclastogenesis and the net outcome of bone formation/resorption. While it is well accepted that mechanical loading in vivo affects bone formation/resorption and that alterations in the responsiveness of bone cells to mechanical loading have been implicated in metabolic bone diseases, the effect of in vitro mechanical loading on osteoblastic production of OPG and RANKL has not been extensively studied. Thus, in the current study, we developed an in vitro model to load human osteoblasts and studied levels of OPG, RANKL, PGE(2) and macrophage colony stimulating factor (M-CSF). We hypothesized that stimulating osteoblastic cells would increase the release of soluble OPG relative to RANKL favoring a bone-forming (and resorption-inhibiting) event. To accomplish this, we developed a small-scale loading machine that imparts via bending, well-defined substrate deformation to bone cells cultured on artificial substrates. Following 2h of loading and a 1h incubation period, media was collected and levels of soluble OPG, RANKL, PGE(2) and M-CSF were quantified using ELISA and western blotting. We found that mechanical loading significantly increased soluble OPG levels relative to RANKL at this 3h time point. Levels of soluble and cellular RANKL detected were not significantly affected by mechanical stimulation. The relative shift in abundance of OPG over RANKL associated with applied mechanical stimulation suggests the soluble OPG:RANKL ratio may be important in load-induced coupling mechanisms of bone cells.
Collapse
|
71
|
Du C, Guan Q, Yin Z, Masterson M, Zhong R, Jevnikar AM. Renal tubular epithelial cell apoptosis by Fas-FasL–dependent self-injury can augment renal allograft injury. Transplant Proc 2003; 35:2481-2. [PMID: 14611992 DOI: 10.1016/j.transproceed.2003.08.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of Fas-FasL interactions in kidney allograft injury may be complex as renal tubular epithelial cells (TEC) express both Fas and FasL. The role and regulation of TEC self-injury has not been investigated. In co-cultures of TEC, FasL-bearing, Fas-null TEC was demonstrated to induce apoptosis of TEC-bearing Fas. Co-culturing effector lpr-TEC (M3.1-lpr) with target WT-TEC (CS3.7) at a ratio of 10:1 (E/T) induced 15.2 +/- 2.4% of target apoptosis as compared to its basal level of 2.6 +/- 0.3%. Similarly lpr-TEC induced apoptosis in gld-TEC (MRM-gld) from a basal level of 3.7 +/- 0.2% to 6.4 +/- 0.3%. Expression of kidney Fas-FasL on injury was tested in a renal transplant model. C57BL/6 (B6) mice were transplanted with Fas-deficient C3H-lpr/lpr or FasL mutation C3H-gld/gld kidneys as compared to normal (wild-type [WT]) C3H/Hej donors. Survival of both lpr and gld recipient was improved compared to WT donors (P <.05) as was function of lpr and gld kidneys indicated by a lower serum creatinine (LPR: 41 +/- 8 micromol/L; GLD: 52 +/- 7 micromol/L) as compared to the WT donors (84 +/- 8 micromol/L, P <.001). These results demonstrate that activated TEC may commit a novel and previously unreported form of self-injury (fractricide) through Fas-FasL. These results suggest that inhibition of renal Fas or FasL might be a useful strategy to prevent TEC loss during rejection.
Collapse
|
72
|
Du C, Meijer GJ, van de Valk C, Haan RE, Bezemer JM, Hesseling SC, Cui FZ, de Groot K, Layrolle P. Bone growth in biomimetic apatite coated porous Polyactive 1000PEGT70PBT30 implants. Biomaterials 2002; 23:4649-56. [PMID: 12322986 DOI: 10.1016/s0142-9612(02)00214-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We recently, developed a simple one-day one-step incubation method to obtain bone-like apatite coating on flexible and biodegradable Polyactive 1000PEGT70PBT30. The present study reports a preliminary biological evaluation on the coated polymer after implantation in rabbit femurs. The porous cylindrical implants were produced from a block fabricated by injection molding and salt leaching. This technique provided the block necessary mechanical integrity to make small cylinders (diameter 3.5 x 5 mm2) that were suitable for implantation in rabbits. The coating continuously covered the surface of the polymer, preserving the porous architecture of outer contour of the cylinders. Two defects with a diameter of 3.5 or 4 mm were drilled in the proximal and distal part of femur diaphysis. The implants were inserted as press-fit or undersized into the cortex as well as in the marrow cavity. The polymer swelled after implantation due to hydration, leading to a tight contact with the surrounding bone in both defects. The adherence of the coating on the polymer proved to be sufficient to endure a steam sterilization process as well as the 15% swelling of the polymer in vivo. The coated Polyactive 1000PEGT70PBT30 has a good osteoconductive property, as manifested by abundant bone growth into marrow cavity along the implant surface during 4-week implantation. A favorable bioactive effect of the coating with an intimate bone contact and extensive bone bonding with this polymer was qualitatively confirmed. Concerning the bone ingrowth into the porous implant in the defect of 4 mm diameter, only marginal bone formation was observed up to 8 weeks with a maximal penetration depth of about 1 mm. The pore interconnectivity is important not only for producing a coating inside the porous structure but also for bone ingrowth into this biodegradable material. This preliminary study provided promising evidence for a further study using a bigger animal model.
Collapse
|
73
|
Du C, Klasens P, Haan RE, Bezemer J, Cui FZ, de Groot K, Layrolle P. Biomimetic calcium phosphate coatings on Polyactive 1000/70/30. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2002; 59:535-46. [PMID: 11774312 DOI: 10.1002/jbm.1267] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Precalcification of Polyactive 1000/70/30 with a biomimetic calcium phosphate coating is expected to enhance the bioactivity of this biodegradable polymer for the application as bone filler or scaffold of bone tissue engineering. This study presents a 1-day one-step incubation method to obtain either amorphous or bone-like apatitic calcium phosphate coating on Polyactive 1000/70/30. Either dense plates or three-dimensional porous blocks of the polymer were incubated in a simplified but concentrated simulated body fluid-derived solution at 37 degrees C. By bubbling CO2 gas, a solution was prepared with calcium and phosphate ion concentrations five times of that of regular simulated body fluid. With controlled stirring, the CO2 was released out of the solution and exchanged by air. The pH of the solution increased to induce coating formation. Adjusting stirring rate and CO2/air exchange rate controlled the process kinetics. The reaction kinetics had little influence on the crystallographic structure of the final coating mineral for a given solution composition as shown by Fourier transform infrared spectroscopy and X-ray diffraction. However, the interface structure between the coating and substrate was kinetics-dependent. A fast precipitation condition resulted in a uniform but superficial calcification pattern at the surface of polymer. A slow process by selecting either a slow stirring or a slow CO2/air exchange, on the contrary, induced a localized but deep inside calcification pattern. A tensile test showed no statistically significant difference in the mechanical properties among uncoated and coated polymers. The cracking behavior of coatings from different kinetics, however, exhibited different manners, as can be attributed to different interface structures and interfacial strengths.
Collapse
|
74
|
Singh AK, Wilson MT, Hong S, Olivares-Villagómez D, Du C, Stanic AK, Joyce S, Sriram S, Koezuka Y, Van Kaer L. Natural killer T cell activation protects mice against experimental autoimmune encephalomyelitis. J Exp Med 2001; 194:1801-11. [PMID: 11748281 PMCID: PMC2193577 DOI: 10.1084/jem.194.12.1801] [Citation(s) in RCA: 320] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Experimental autoimmune encephalomyelitis (EAE) serves as a prototypic model for T cell-mediated autoimmunity. V(alpha)14 natural killer T (NKT) cells are a subset of T lymphocytes that recognize glycolipid antigens presented by the nonpolymorphic major histocompatibility complex (MHC) class I-like protein CD1d. Here, we show that activation of V(alpha)14 NKT cells by the glycosphingolipid alpha-galactosylceramide (alpha-GalCer) protects susceptible mice against EAE. beta-GalCer, which binds CD1d but is not recognized by NKT cells, failed to protect mice against EAE. Furthermore, alpha-GalCer was unable to protect CD1d knockout (KO) mice against EAE, indicating the requirement for an intact CD1d antigen presentation pathway. Protection of disease conferred by alpha-GalCer correlated with its ability to suppress myelin antigen-specific Th1 responses and/or to promote myelin antigen-specific Th2 cell responses. alpha-GalCer was unable to protect IL-4 KO and IL-10 KO mice against EAE, indicating a critical role for both of these cytokines. Because recognition of alpha-GalCer by NKT cells is phylogenetically conserved, our findings have identified NKT cells as novel target cells for treatment of inflammatory diseases of the central nervous system.
Collapse
|
75
|
Du C, Khalil MW, Sriram S. Administration of dehydroepiandrosterone suppresses experimental allergic encephalomyelitis in SJL/J mice. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:7094-101. [PMID: 11739531 DOI: 10.4049/jimmunol.167.12.7094] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Experimental allergic encephalomyelitis (EAE) is a Th1-mediated inflammatory demyelinating disease in the CNS, an animal model of multiple sclerosis. We have examined the effect of dehydroepiandrosterone (DHEA) on the development of EAE in mice. The addition of DHEA to cultures of myelin basic protein-primed splenocytes resulted in a significant decrease in T cell proliferation and secretion of (pro)inflammatory cytokines (IFN-gamma, IL-12 p40, and TNF-alpha) and NO in response to myelin basic protein. These effects were associated with a decrease in activation and translocation of NF-kappaB. In vivo administration of DHEA significantly reduced the severity and incidence of acute EAE, along with a decrease in demyelination/inflammation and expressions of (pro)inflammatory cytokines in the CNS. These studies suggest that DHEA has potent anti-inflammatory properties, which at least are in part mediated by its inhibition of NF-kappaB activation.
Collapse
MESH Headings
- Active Transport, Cell Nucleus/drug effects
- Animals
- Anti-Inflammatory Agents/therapeutic use
- Cell Nucleus/metabolism
- Cells, Cultured
- Dehydroepiandrosterone/therapeutic use
- Encephalomyelitis, Autoimmune, Experimental/drug therapy
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Female
- Interferon-gamma/biosynthesis
- Interferon-gamma/genetics
- Interleukin-12/biosynthesis
- Interleukin-12/genetics
- Lymphocyte Activation/drug effects
- Mice
- Mice, Inbred Strains
- Myelin Basic Protein/immunology
- NF-kappa B/metabolism
- Nitric Oxide/biosynthesis
- RNA, Messenger/biosynthesis
- Spinal Cord/immunology
- Spinal Cord/pathology
- Spleen/immunology
- Th1 Cells/drug effects
- Th1 Cells/immunology
- Tumor Necrosis Factor-alpha/biosynthesis
- Tumor Necrosis Factor-alpha/genetics
Collapse
|