Biomedical subjects

A Tesnière

Publications and source records attributed to A Tesnière.

3 recordsLinked to original sources

PubMed2004

Thiopental and isoflurane attenuate the decrease in hippocampal phosphorylated Focal Adhesion Kinase (pp125FAK) content induced by oxygen-glucose deprivation.

BACKGROUND: Thiopental and isoflurane exhibit neuroprotective effects against cerebral ischaemia. Here, we hypothesized that oxygen-glucose deprivation decreases the ATP-dependent phosphorylation process of Focal Adhesion Kinase (pp125FAK, a functionally important non-receptor tyrosine kinase), and that this phenomenon is attenuated by thiopental and isoflurane. METHODS: Rathippocampal slices were subjected to an anoxic-aglycaemic (or physiologic, control) challenge followed by 3-h reperfusion, and treated with various concentrations of thiopental and isoflurane. PP125FAK phosphorylation was measured by immunoblotting. Neuronal death was assessed by immunostaining with bis-benzimide. RESULTS: Significant neuronal death was detected after 30 min (but not 10) of anoxia-aglycaemia (40 (4) vs 14 (5)% of control, P<0.05). At 30 min, phosphorylated pp125FAK content was significantly decreased by anoxic glucose-free conditions (55 (27)% of control, P<0.05). This effect was markedly attenuated by thiopental (10 and 100 microM) and isoflurane (1 and 2%). Under control conditions, thiopental (1, 10, and 100 microM) and isoflurane (0.5, 1, and 2%) increased pp125FAK phosphorylation in a concentration-related fashion. This effect was blocked by chelerythrin and bisindolylmaleimide I and IX (10 microM, three structurally distinct inhibitors of protein kinase C, PKC) but not the N-methyl-D-aspartate (NMDA) receptor antagonist MK801 (10 microM). CONCLUSION: Phosphorylated pp125FAK content was markedly decreased in hippocampal slices subjected to oxygen-glucose deprivation. Thiopental and isoflurane significantly attenuated this phenomenon, possibly via PKC activation.

Adenosine Triphosphate↗

PubMed1997

The proto-oncogene c-fos increases the sensitivity of keratinocytes to apoptosis.

In human skin, most studies have suggested a role of c-fos or c-fos related genes in keratinocyte differentiation. The aim of our work was to more directly address this question by transfecting more or less differentiated keratinocyte cell lines (A431 and HaCaT) with constitutive expression vectors for c-Fos or c-Fos + c-Jun. Our results showed that c-Fos expression decreased keratinocyte growth, yet addition of c-Jun seemed to revert this c-Fos induced growth inhibition. Whereas no obvious differentiation program was turned on by c-Fos or c-Fos + c-Jun expression in our tissular model, apoptotic figures were observed and confirmed by in situ DNA fragmentation studies. These results do not rule out a role of c-Fos in keratinocyte differentiation but may indicate that the cell lines we used have reached an irreversible state of transformation so that they no longer respond to differentiation signals and rather die from apoptosis. These data add further evidence in favor of a role of c-Fos in epidermal homeostasis.

Apoptosis↗

PubMed1994

Comparative analysis of normal and psoriatic skin both in vivo and in vitro.

The morphological and biochemical characteristics of psoriasis are well documented, but the pathogenesis of this disease is not clearly understood. A variety of in vitro models of psoriasis have been developed in attempts to identify the trigger factors, but no model so far reproduces the stable psoriatic phenotype accurately. In the present work, we initially checked the immunohistochemical distribution of proliferation/differentiation markers in psoriatic skin in vivo, and our results largely confirm previously reported data. However the study was performed using a new series of monoclonal antibodies to keratin. Subsequently we took normal or psoriatic skin biopsies, reconstructed skin equivalents using a recently described model and analysed the proliferation/differentiation status of the resulting epidermis. Dramatic morphological and antigenic differences were found between normal and psoriatic skin in vivo, but whatever the source of the initial biopsy, a unique in vitro phenotype was obtained in the reconstructed epidermis. This phenotype was marked by mild hyperproliferation and an altered distribution of differentiation-associated antigens suggesting a need for extracutaneous stimuli to maintain the psoriatic phenotype in vitro.

Antibodies, Monoclonal↗