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L Tranqui

Publications and source records attributed to L Tranqui.

22 records · Page 2Linked to original sources
PubMed1977

The proteolytic action of bacterial proteases from Clostridium histolyticum on bovine fibrinogen.

Bacterial proteases from Clostridium histolyticum bring about the polymerization of fibrinogen into structured fibres, the period being 9 nm when the ionic strength (I) of the solution is between 0.1 and 0.2. At I=0.3 no polymerization occurs, but the successive actions of bacterial proteases and thrombin induce polymerization, the fibres obtained showing a periodic structure: the major period is 23 nm with two minor striations. The striation pattern is different from that obtained with fibrin which shows a major period of 23 nm with three minor striations. The degree of degradation of fibrinogen monitored by disc gel electrophoresis shows that the Aalpha polypeptide chain (mol. wt.=68 000) is degraded into Aalpha1 (mol. wt.=32 000) and Aalpha2 (mol. wt.=29 000), whilst the mobility of Bbeta increases and gamma remains unchanged; the molecular weight is estimated between 272 000 and 269 000. These results emphasize that the charge distribution differences which are compatible with the loss of different portions of the molecule, lead to variations in fibre structures.

Animals↗
PubMedDate not supplied

In vitro angiogenesis is modulated by the mechanical properties of fibrin gels and is related to alpha(v)beta3 integrin localization.

This study deals with the role of the mechanical properties of matrices in in vitro angiogenesis. The ability of rigid fibrinogen matrices with fibrin gels to promote capillarylike structures was compared. The role of the mechanical properties of the fibrin gels was assessed by varying concentration of the fibrin gels. When the concentration of fibrin gels was decreased from 2 mg/ml to 0.5 mg/ml, the capillarylike network increased. On rigid fibrinogen matrices, capillarylike structures were not formed. The extent of the capillarylike network formed on fibrin gels having the lowest concentration depended on the number of cells seeded. The dynamic analysis of capillarylike network formation permitted a direct visualization of a progressive stretching of the 0.5 mg/ml fibrin gels. This stretching was not observed when fibrin concentration increases. This analysis shows that 10 h after seeding, a prearrangement of cells into ringlike structures was observed. These ringlike structures grew in size. Between 16 and 24 h after seeding, the capillarylike structures were formed at the junction of two ringlike structures. Analysis of the alpha(v)beta3 integrin localization demonstrates that cell adhesion to fibrinogen is mediated through the alpha(v)beta3 integrin localized into adhesion plaques. Conversely, cell adhesion to fibrin shows a diffuse and dot-contact distribution. We suggest that the balance of the stresses between the tractions exerted by the cells and the resistance of the fibrin gels triggers an angiogenic signal into the intracellular compartment. This signal could be associated with modification in the alpha(v)beta3 integrin distribution.

Biomechanical Phenomena↗