Soft tissue adhesion of polished versus glazed lithium disilicate ceramic for dental applications.

OBJECTIVE: Ceramics are widely used materials for prosthesis, especially in dental fields. Despite multiple biomedical applications, little is known about ceramic surface modifications and the resulting cell behavior at its contact. The aim of this study is to evaluate the biological response of polished versus glazed surface treatments on lithium disilicate dental ceramic. METHODS: We studied a lithium disilicate ceramic (IPS e.max(®) Press, Ivoclar Vivadent) with 3 different surface treatments: raw surface treatment, hand polished surface treatment, and glazed surface treatment (control samples are Thermanox(®), Nunc). In order to evaluate the possible modulation of cell response at the surface of ceramic, we compared polished versus glazed ceramics using an organotypic culture model of chicken epithelium. RESULTS: Our results show that the surface roughness is not modified as demonstrated by equivalent Ra measurements. On the contrary, the contact angle θ in water is very different between polished (84°) and glazed (33°) samples. The culture of epithelial tissues allowed a very precise assessment of histocompatibility of these interfaces and showed that polished samples increased cell adhesion and proliferation as compared to glazed samples. SIGNIFICANCE: Lithium disilicate polished ceramic provided better adhesion and proliferation than lithium disilicate glazed ceramic. Taken together, our results demonstrate for the first time, how it is possible to use simple surface modifications to finely modulate the adhesion of tissues. Our results will help dental surgeons to choose the most appropriate surface treatment for a specific clinical application, in particular for the ceramic implant collar.

Microstructure, mechanical properties and cytocompatibility of stable beta Ti-Mo-Ta sintered alloys.

We have synthesized titanium-based alloys containing molybdenum and tantalum elements by powder metallurgy. The microstructure, the residual porosity and the mechanical properties of the sintered Ti-Mo and Ti-Ta-Mo alloys were investigated by using optical and electronic microscopy, X-ray diffraction, microhardness and compression tests. The cytocompatibility of the different alloys was evaluated by the assessment of bone cell density, migration and adhesion after 14 days incubation. All the alloys present a high ductility and an excellent cytocompatibility, which make these materials useful for medical implants.

Interactions of B16F10 melanoma cells aggregated on a cellulose substrate.

There is evidence that the shape of cells and their contact with a matrix direct the growth and the differentiation of both normal and cancer cells. Cells in 3D culture resemble the in vivo situation more closely than do those in conventional 2D cultures. We have studied the interactions and functions of B16F10 mouse melanoma cells, which spread and grow well on tissue culture polystyrene (tPS), when they were made to aggregate on cellulose-coated Petri dishes (CEL). This aggregation of melanoma cells on CEL was Ca2+ dependent and mediated by N-cadherins. The levels of N-cadherin and beta-catenin transcripts in cells cultured on CEL and tPS were similar, but those on CEL contained less beta-catenin protein. Immunoprecipitation and immunostaining showed that both N-cadherins and beta-catenins were present at the membranes of cells on CEL. Cells proliferated significantly more slowly after 48 h on CEL and the cellulose coating caused most of them to arrest in G1. We also compared the melanin contents and tyrosinase activity of cells on CEL and controls grown on tPS. Melanogenesis was induced in cells aggregated on CEL. A cellulose substrate thus appears to be an outstanding tool for studying cell-cell interactions and cell functions in 3D cultures.

Development of a beta-type Ti-12Mo-5Ta alloy for biomedical applications: cytocompatibility and metallurgical aspects.

Ti-based biocompatible alloys are especially used for replacing failed hard tissue. Some of the most actively investigated materials for medical implants are the beta-Ti alloys, as they have a low elastic modulus (to inhibit bone resorption). They are alloyed with elements such as Nb, Ta, Zr, Mo, and Fe. We have prepared a new beta-Ti alloy that combines Ti with the non-toxic elements Ta and Mo using a vacuum arc-melting furnace and then annealed at 950 degrees C for one hour. The alloy was finally quenched in water at room temperature. The Ti-12Mo-5Ta alloy was characterised by X-ray diffraction, optical microscopy, SEM and EDS and found to have a body-centred-cubic structure (beta-type). It had a lower Young's modulus (about 74 GPa) than the classical alpha/beta Ti-6Al-4V alloy (120 GPa), while its Vickers hardness remained very high (about 303 HV). This makes it a good compromise for a use as a bone substitute. The cytocompatibility of samples of Ti-12Mo-5Ta and Ti-6Al-4V titanium alloys with various surface roughnesses was assessed in vitro using organotypic cultures of bone tissue and quantitative analyses of cell migration, proliferation and adhesion. Mechanically polished surfaces were prepared to produce unorientated residual polished grooves and cells grew to a particularly high density on the smoother Ti-12Mo-5Ta surface tested.

Comparative particle-induced cytotoxicity toward macrophages and fibroblasts.

The cytotoxicity caused by the debris resulting from wear of prostheses can produce major damage to tissues around the implant. We have compared particle internalization by macrophages and fibroblasts in vitro and analyzed cell death. J774.2 macrophages and L929 fibroblasts were incubated with 0.43 and 2.81 microm alumina particles or 0.45 and 3.53 microm polystyrene (PS) beads. Incubation of J774.2 cells with alumina particles of both sizes and 0.5 and 1.0 mg/ml PS beads significantly decreased cell numbers in a particle concentration-dependent manner. L929 cells were not affected by lower concentrations of 0.43 microm alumina particles (which aggregate at high concentrations) and they internalized 0.45 microm PS beads without any decrease in cell numbers. Particles were more cytotoxic for macrophages than for fibroblasts. Particles caused the size of both types of cells to increase in correlation with cytotoxicity. Trypan blue exclusion and lactate dehydrogenase release showed cell membrane leakage for both types of cells incubated with PS beads for 24 h. Apoptosis was assessed by annexin V-FITC, propidium iodide staining and assay of caspase 3 activity. Macrophage death appeared to depend on both necrosis, caused mainly by 3.53 microm PS beads, and apoptosis, mainly due to 0.45 microm PS beads. The release of the inflammatory cytokine IL-6 appears to be nonlinearly correlated with cytotoxicity. Thus, the size of the internalized particles affects macrophages and fibroblasts differently, and the increase in cell size can be used as a preliminary criterion of particle cytotoxicity in vitro.

Embolic risk of the different stages of carotid bifurcation balloon angioplasty: an experimental study.

PURPOSE: Embolic events during carotid angioplasty are a challenging problem. This experimental study was undertaken to determine the embolic risk after each stage of carotid angioplasty procedure. METHODS: Five ex vivo carotid artery balloon angioplasties were performed on fresh carotid specimens. The carotid specimens were obtained from five patients who underwent an internal carotid artery bypass for stenosis >75%. Before the endovascular maneuvers and after each stage of the procedures, the specimens were flushed with 20 mL of saline solution. Small particulate emboli (diameter, <60 microm) were searched in all the effluents according to the Coulter technique. After this procedure, each effluent was also submitted to scanning electron microscopy. RESULTS: When the stenosis was crossed with the guidewire or the balloon catheter, the number and the mean diameter of embolic particles did not change with three plaques (CP1, CP2, and CP3) and were increased with two plaques (CP4 and CP5). The maximal size of particles was 220 microm (CP5). After balloon angioplasty, the number and the mean diameter of particles increased with CP1, CP2, and CP3. With CP4 and CP5, the number of particles decreased, but their size increased. The maximal size of particles was 1100 microm (CP4). CONCLUSION: Carotid balloon angioplasty generates embolic particles after each stage of the procedure. Techniques of prevention should then be effective from the initial step of the angioplasty procedure, and the selection of patients for carotid angioplasty remains crucial.

cAMP levels in cells attached to AN69 and Cuprophan: cAMP dependence of cell aggregation and the influence of serum.

We have examined the link between the aggregation or spreading of cells adhering to substrata of differing biocompatibility and activation of the cyclic AMP (cAMP) pathway. We compared the rate at which the Mouse Swiss 3T3 fibroblasts attached to Cuprophan (CU), AN69 and a control plastic in the presence and absence of foetal calf serum (FCS). Serum had no effect on the kinetics of cell attachment to CU or AN69. Cells incubated in culture medium containing 10% FCS aggregated on CU, whereas they spread on AN69 and plastic. Aggregated cells contained significantly higher concentrations of cAMP than cells spreading, and aggregation was prevented by treatment with miconazole, an inhibitor of adenylyl cyclase. cAMP-dependent cell aggregation occurred on all three substrata in serum-free medium, suggesting that proteins adsorbed onto AN69 and plastic in the presence of serum helped protect the cells. Far less serum protein was adsorbed onto CU than onto AN69 or plastic, consistent with the similar increases in cAMP in cells attached to CU with or without serum.

[Portal vein thrombosis and rupture of the esophagus secondary to a barotrauma]. / Thrombose porte et rupture de l'oesophage secondaires à un barotraumatisme.

Portal vein thrombosis complicating a trauma is rare. We report a case of portal vein thrombosis associated with esophageal rupture after a blast injury due to the explosion of a pressurized nitrogen bottle. Portal vein thrombosis was discovered during oesophageal reconstruction, 70 days after the initial injury. A favorable outcome was observed.

Cytocompatibility of calf pericardium treated by glutaraldehyde and by the acyl azide methods in an organotypic culture model.

Glutaraldehyde (GTA) is used to cross-link collagen-based biomaterials, but these materials are often cytotoxic. In order to overcome this problem, we have proposed the use of the acyl azide methods with either hydrazine or diphenylphosphoryl azide (DPPA) as reagents. In this paper we determine the cytocompatibility of acyl azide- and GTA-treated pericardium in vitro, by an organotypic chick aorta culture technique developed for the evaluation of the propensity of vascular cells (both endothelial and smooth muscle cells) to migrate and grow on the surface of biomaterials. We first examined pericardium stabilization as a function of GTA concentration and time, so that we could minimize residual GTA molecules in the material. Treatment for 72 h with 0.05% GTA was optimal for thermal stabilization of the pericardium with a denaturation temperature (Td) of 86.8 degrees C, providing similar results to treatment with 0.6% GTA for 4 h (Td = 85.1 degrees C). Pericardium treated in this way was, however, poorly cytocompatible with little vascular cell migration and growth when compared with tissues treated by the acyl azide methods. The best results were obtained with 0.5% DPPA; treated tissues showed a high level of cross-linking (Td = 82.4 degrees C) and three-fold increases in cell growth and migration over those in a non-toxic control.

[Spondylodiscitis disclosing endocarditis on the endocavitary electrodes of cardiac pacemakers]. / Spondylodiscites révélatrices d'endocardite sur électrodes endocavitaires de stimulateurs cardiaques.

Permanent pacemaker electrode infection is rare but can be fatal. The authors report two cases presenting with spondylodiscitis, a previously described mode of presentation of valve endocarditis but not previously reported in this context. In one case, recurrent courses of antibiotics did not prevent repeated episodes of bacteraemia. In the second, the relapse of infection occurred at different sites of the vertebral column until surgical removal of the electrodes: the usual features of this pathology were observed: frequent but not constant infection at the site of the pacemaker implantation, making the diagnosis more difficult; delayed signs of spondylodiscitis after implantation of the pacemaker; recurrence of infection when antibiotic therapy alone was prescribed and, therefore, the need for surgical ablation of all implanted material. The authors underline the diagnostic value of transoesophageal echocardiography.

Biliary stenting in benign biliary stenosis complicating chronic calcifying pancreatitis.

This a retrospective study of 19 patients presenting with chronic pancreatitis and benign stenosis of the common bile duct, who were followed up for periods ranging from 13 months to 48 months after biliary stenting (average 18 months). There were 18 men and one woman, aged between 38 and 65 years (average 49 years). The mean duration of the disease before stenting was seven years (range 1-25 years). Symptoms were present in ten patients: obstructive jaundice in four cases, cholangitis in three cases, and biliary colic in three cases. Nine patients without clinical complaints presented with chronic cholestasis. Endoscopic retrograde cholangiopancreatography (ERCP) showed 15 long, regular stenoses of the intrapancreatic course of the common bile duct, three short stenoses located at the upper margin of the head of the pancreas, and one biliary stenosis associated with peripheral compression by a cyst of the head of the pancreas. Forty endoscopic biliary stenting procedures were performed in the 19 patients over a six-year period. Successful insertion of the prosthesis was achieved in 39 cases. Two complications occurred: one duodenal ulceration and one stent migration into the bile duct. The mean duration of biliary stenting was ten months. Only two patients (10%) had complete clinical, biological, and radiological recovery. Complete failure of biliary stenting was observed in six patients (31%). Eleven patients (59%) had partial results: six (31%) had biological improvement although the biliary stricture persisted, and five were clinically asymptomatic but had cholestasis, and still presented with biliary stenosis in four cases.(ABSTRACT TRUNCATED AT 250 WORDS)

[Angiosarcoma of the aorta revealed by an intestinal metastasis]. / Angiosarcome aortique révélé par une métastase intestinale.

We report a case of aortic endothelioma revealed by intestinal metastasis in a man who was admitted for severe anemia, left heart failure, and fatal ileo-mesenteric infarction. This is the 13th published case of aortic endothelioma, and the first case revealed by intestinal metastasis. It illustrates the value of the magnetic resonance imaging for the detection of an aortic tumor when intestinal angiosarcoma has been diagnosed. The surgical treatment could improve an otherwise very poor prognosis.

[Angiosarcoma of the aorta disclosed by intestinal metastasis]. / Angiosarcome de l'aorte révélé par une métastase intestinale.

The authors report a case of angiosarcoma of the descending thoracic aorta presenting with a metastasis of the small intestine. This is a very rare tumour in this localisation, two cases having been described among the 28 cases of aortic tumour reported in the literature.