Comparative assessment of cell/substratum static adhesion using an in vitro organ culture method and computerized analysis system.

The trypsin sensitivity of chick embryo cellular layers cultivated by an in vitro organ culture method toward different biomaterials has been analysed. Monolayer cells grown on to tested samples were enzymatically dissociated in 5 min - 1 h. Cumulative cell numbers, expressed as the percentage of the totally detached cell number, were plotted versus time, thus permitting the calculation of the function. The mathematical treatment by a computerized system of this function represents the trypsin sensitivity. This value modulated by the migration cell number is the static adhesion modulated index (SAMI). The trypsin sensitivity expressed according to this index allowed the establishment of an abacus wherein several zones, A, B, C and D, define cell adhesion behaviour on different biomaterials. Scanning electron microscopy analysis performed on dissociation steps showed the selective activity of trypsin on cells toward different substrata, revealing the role of an extracellular matrix and cytoskeleton in the adhesion behaviour.

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.

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.

[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.

[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.

[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.

[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.

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.

[Effect of the pHi of protein membranes on cellular affinity in in vitro culture]. / Etude de l'influence de pHi de membranes protéiques sur l'affinité cellulaire en culture in vitro.

We compare in vitro, the cellular affinity of different proteic membranes in terms of their isoelectric point. This parameter reveals some electric charge oppositions among these materials and, in our experimental conditions, it seems to have no influence on their biocompatibility.