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Biomedical subjects

P Payrau

Publications and source records attributed to P Payrau.

At least 19 recordsLinked to original sources

Comparative biochemical and morphometric studies on corneal wound healing.

Comparative biochemical and morphological studies were carried out on wounded corneas in order to correlate biochemical findings with morphometric observations during the healing process. Experimental production of corneal wounds, biochemical determinations and quantitative morphometric studies are described in an attempt to correlate corneal matrix macromolecules biosynthesis during the healing process with the morphological modifications of the tissue. The central part and the peripheral part of the corneas were examined separately and compared to the central and peripheral parts of the controlateral corneas. The DNA content of the central portion of the wounded corneas progressively increased and reached after 60 days the same level as the corresponding portion of the controlateral corneas. The DNA contents of the peripheral portions of wounded and controlateral corneas are persistently higher than the DNA contents in the central portion. In peripheral portions of wounded corneas the DNA content is higher than in controlateral corneas and continues to increase steadily during the 60 days of experimentation. Cell density, as determined by morphometry, increased also during that period. The differences between the evolution of the DNA contents and cell density curves may be attributed to variations in cell sizes. The collagen content, estimated from hydroxyproline determinations remained lower in the wounded corneas as compared to the controlateral corneas, even 60 days after operation. This was true for the central as well as for the peripheral portions, suggesting a collagenolytic process as a result of wounding. This is confirmed by morphometric evaluation of fiber density.(ABSTRACT TRUNCATED AT 250 WORDS)

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[Regeneration of corneal endothelium in the rabbit: microscopic study and relation with corneal thickness].

The corneal cells are destroyed within a 10 mm diameter circular belt by liquid nitrogen application in vivo. The endothelial regeneration is followed from day to day using endothelial flat preparation technic, and is compared to the corneal thickness measurement and to the estimation of transparency. From the 5th day, Descemet's membrane is entirely covered by the regenerated endothelium; from this time, both thickness and transparency of the stroma become normal. Therefore, in spite of the persitence of morphologic abnormalities, the regenerating endothelial cells preserve or obtain again very rapidly their specific function of a barrier against hydration of the stroma.

Animals↗

[Regulation of the biosynthesis of macromolecules of the intercellular corneal matrix].

The influence of a 1M CaCl2 extract and of a collagenase digest of corneal stroma of the biosynthesis of the macromolecules of corneal stroma was investigated. Calf corneas were incubated "in vitro" with radioactive tracers (14C-L-proline; 3H-D-glucosamine or 35SO4) in the presence or absence of the above extracts. After incubation the corneas are submitted to a fractional extraction in order to separate the major macromolecular fractions of the stroma. An increase in incorporation of all tracers is observed in the 1M CaCl2 (CTC), TCA and urea-extracts (containing resp. the diffusible macromolecules, proteoglycans, polymeric collagen and structural glycoproteins) in the presence of the macromolecular extracts and also with the collagenase-hydrolysate of cornea. These results show the existence of a stimulation of the biosynthesis of intracellular matrix macromolecules of the cornea by corneal extracts, probably through positive "feedback" type of mechanism.

Animals↗