PURPOSE: Normal corneal hydration is necessary for the maintenance of corneal transparency. Damage of the corneal epithelium or endothelium by various external influences disturbs the mechanism by which the cornea maintains normal hydration and transparency. The cornea swells, and the corneal thickness increases, resulting in increased scatter and the development of corneal opacity. The transmission of light across the cornea is changed. The purpose of this study is to investigate spectrophotometrically the corneal light transmission under the influence of the various factors affecting the cornea. METHODS: We developed a spectrophotometric method to measure the light transmission across the cornea under the influence of various factors affecting the cornea, such as treatment with 0.9% NaCl, saline, or phosphate buffered saline (PBS), solutions employed as placebo eye drops (negative controls) in experimental studies, agents toxic to the cornea, such as diluted acids or alkalis. The method distinguishes between changes in corneal light transmission caused by altered corneal thickness (the level of hydration) and changes resulting from other corneal disturbances which in turn affect corneal light transmission. RESULTS: The results obtained show that the corneal light transmission is decreased following the application of toxic substances on the corneal surface. This decrease is highly dependent on the severity of the corneal injury evoked by individual noxes, and the resulting changes in corneal hydration and transparency. CONCLUSIONS: The influence of various influences applied to the cornea, manifested as changes in corneal light transmission, can be measured using our spectrophotometric method with a high degree of sensitivity.

• MeSH
• edém rohovky chemicky indukované   MeSH
• hydroxid sodný toxicita   MeSH
• králíci MeSH
• kyselina chlorovodíková toxicita   MeSH
• rohovka účinky léků   účinky záření   MeSH
• spektrofotometrie MeSH
• světlo * MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• hydroxid sodný MeSH
• kyselina chlorovodíková MeSH

Plasmin, a serine protease, was recently found to be involved in corneal ulcerative processes in humans and rabbits. In our experiments, plasmin activity was found in the tear fluid after mechanical and chemical damage of the rabbit cornea, such as de-epithelization and burning with alkali. The plasmin concentrations in the tear fluid were dependent on the severity of injury. The highest plasmin activity (2.0-3.0 micrograms ml-1) occurred after severe alkali damage to large areas of the cornea, and the lowest activity (0.4-1.0 micrograms ml-1) after mechanical injury (de-epithelization). Plasmin concentrations up to 1.0 micrograms ml-1 were associated with increased activities of lysosomal hydrolases in epithelial cells and keratocytes beneath the epithelium. Plasmin activities increased as the inflammatory reaction developed. When plasmin activity in the tear fluid was higher than 1.0 micrograms ml-1, inflammatory cells were found in the corneal stroma. Levels of 1.5-2.0 micrograms ml-1 were connected with higher numbers of inflammatory cells (particularly polymorphonuclear leukocytes) with increased activities of lysosomal hydrolases. Very high plasmin activities (2.5-3.0 micrograms ml-1) accompanied corneal ulcerative processes. The local application of aprotinin (Trasylol, Bayer), an inhibitor of plasmin, and also of some other proteases, was found to be necessary for the healing of severe corneal injuries in which highly elevated plasmin activity in the tear fluid and inflammatory cellulization of the cornea occurred (severe damage).(ABSTRACT TRUNCATED AT 250 WORDS)

• MeSH
• aprotinin farmakologie   terapeutické užití   MeSH
• beta-galaktosidasa metabolismus   MeSH
• dipeptidylpeptidasy a tripeptidylpeptidasy metabolismus   MeSH
• hydrolasy metabolismus   MeSH
• králíci MeSH
• lyzozomy enzymologie   MeSH
• neutrofily enzymologie   MeSH
• plasmin analýza   MeSH
• poranění rohovky * MeSH
• slzy enzymologie   MeSH
• vřed rohovky chemicky indukované   farmakoterapie   enzymologie   MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aprotinin MeSH
• beta-galaktosidasa MeSH
• dipeptidylpeptidasy a tripeptidylpeptidasy MeSH
• hydrolasy MeSH
• plasmin MeSH

Plasmin activity in the tear fluid of the rabbit eye was examined during the wearing of soft contact lenses (SCL) and compared with the occurrence of corneal disturbances assessed in cryostat sections. Plasmin activity was determined with a semiquantitative method using dry punches of filter paper previously soaked in 0.1 M Tris-HCl buffer solution containing mmol/l D-Val-Leu-Lys-FCA (trifluoromethylaminocoumarine), pH 7.2. Punches were applied to the corneal surface for 5 s (tear collection) and incubated in wet chamber. The time of appearance of the bright yellow fluorescence in UV light was recorded and taken as a measure of plasmin activity. For calibration punches soaked in solutions containing plasmin in various concentrations, and processed in the same manner were used. Changes in the cornea were examined histochemically using methods of choice for acid glycosidases, proteases, dehydrogenases, and Na(+)-K(+)-ATPase. SCL with high and low water content were worn in rabbits in 1, 2, 4, 7, 14, 21 and 28 days. Decreased activity of Na(+)-K(+)-ATPase, GGT, and SDH in the corneal endothelium and epithelium were not accompanied by detectable plasmin activity in the tear fluid. Pronounced damage of the corneal epithelium (increased activities of acid glycosidases, acid proteases, LDH, markedly decreased activity of SDH) was accompanied by low concentration of plasmin (0.4-1.0 micrograms/ml) in the tear fluid. Middle activity of plasmin (1.0-2.0 micrograms/ml) was detectable when PMNs were present in the corneal stroma. High plasmin activity (2.0-3.0 micrograms/ml) correlated with corneal ulceration and vascularization.(ABSTRACT TRUNCATED AT 250 WORDS)

• MeSH
• aprotinin farmakologie   MeSH
• činčila MeSH
• epitel účinky léků   enzymologie   MeSH
• flurbiprofen farmakologie   MeSH
• histocytochemie MeSH
• inhibitory proteas farmakologie   MeSH
• karbamáty farmakologie   MeSH
• králíci MeSH
• měkké kontaktní čočky škodlivé účinky   MeSH
• oligopeptidy farmakologie   MeSH
• pankreatická elastasa antagonisté a inhibitory   MeSH
• plasmin metabolismus   MeSH
• rohovka enzymologie   metabolismus   MeSH
• slzy účinky léků   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aprotinin MeSH
• elastatinal MeSH Prohlížeč
• flurbiprofen MeSH
• inhibitory proteas MeSH
• karbamáty MeSH
• oligopeptidy MeSH
• pankreatická elastasa MeSH
• plasmin MeSH
• tetrapeptide carbamate MeSH Prohlížeč