C Cejka

The Police Academy of the Czech Republic in Prague, Praha, Praha, Czech Republic

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Publications (22)46.95 Total impact

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    ABSTRACT: Purpose Purpose. To test a possibilty to treat the early corneal inflammation occuring after alkali injury by nanofiber scaffolds seeded with mesenchymal stem cells (MSCs) or loaded with cyclosporine A (CsA).Methods Methods. The alkali was applied on the cornea of the rabbit eyes. The eyes were rinsed with the excess of physiological solution and covered with nanofiber scaffold seeded with rabbit bone marrow-derived MSCs or with nanofibers loaded with CsA. At different time intervals after the injury the eyes were analyzed macroscopically, immunohistochemically and biochemically.Results Results. Treatment of alkali-injured eyes with MSCs or CsA significantly attenuated the local inflammatory reaction. The therapeutic effects were characterized clinically, according to a reduced infiltration with inflammatory cells, by a lower neovascularization and by decreased expression of genes for proinflammatory molecules IL-1beta, IL-2, IFN-gamma and iNOS and for vascular endothelial growth factor. These anti-inflammatory effects were accompanied by a more rapid regeneration of the corneal epithelium and by increased expression of gene for cytokeratin K12.Conclusion Conclusion. The results demonstrate that MSC-seeded or CsA-loaded nanofiber scaffolds represent a promising therapeutic tool for the treatment of alkali-induced ocular surface injuries
    Acta ophthalmologica 09/2014; 92(s253). · 2.44 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate whether rabbit bone marrow-derived mesenchymal stem cells (MSCs) effectively decrease alkali-induced oxidative stress in the rabbit cornea. The alkali (0.15 N NaOH) was applied on the corneas of the right eyes and then rinsed with tap water. In the first group of rabbits the injured corneas remained untreated. In the second group MSCs were applied on the injured corneal surface immediately after the injury and eyelids sutured for two days. Then the sutures were removed. In the third group nanofiber scaffolds seeded with MSCs (and in the fourth group nanofibers alone) were transferred onto the corneas immediately after the injury and the eyelids sutured. Two days later the eyelid sutures were removed together with the nanofiber scaffolds. The rabbits were sacrificed on days four, ten or fifteen after the injury, and the corneas were examined immunohistochemically, morphologically, for the central corneal thickness (taken as an index of corneal hydration) using an ultrasonic pachymeter and by real-time PCR. Results show that in untreated injured corneas the expression of malondialdehyde (MDA) and nitrotyrosine (NT) (important markers of lipid peroxidation and oxidative stress) appeared in the epithelium. The antioxidant aldehyde dehydrogenase 3A1 (ALDH3A1) decreased in the corneal epithelium, particularly in superficial parts, where apoptotic cell death (detected by active caspase-3) was high. (In control corneal epithelium MDA and NT are absent and ALDH3A1 highly present in all layers of the epithelium. Cell apoptosis are sporadic). In injured untreated cornea further corneal disturbances developed: The expressions of matrix metalloproteinase 9 (MMP9) and proinflammatory cytokines, were high. At the end of experiment (on day 15) the injured untreated corneas were vascularized and numerous inflammatory cells were present in the corneal stroma. Vascular endothelial growth factor (VEGF) expression and number of macrophages were high. The results obtained in injured corneas covered with nanofiber scaffolds alone (without MSCs) or in injured corneas treated with MSCs only (transferred without scaffolds) did not significantly differ from the results found in untreated injured corneas. In contrast, in the injured corneas treated with MSCs on nanofiber scaffolds, ALDH3A1 expression remained high in the epithelium (as in the control cornea) and positive expression of the other immunohistochemical markers employed was very low (MMP9) or absent (NT, MDA, proinflammatory cytokines), also similarly as in the control cornea. Corneal neovascularization and the infiltration of the corneal stroma with inflammatory cells were significantly suppressed in the injured corneas treated with MSCs compared to the untreated injured ones. The increased central corneal thickness together with corneal opalescency appearing after alkali injury returned to normal levels over the course of ten days only in the injured corneas treated with MSCs on nanofiber scaffolds. The expression of genes for the proinflammatory cytokines corresponded with their immunohistochemical expression. In conclusion, MSCs on nanofiber scaffolds protected the formation of toxic peroxynitrite (detected by NT residues), lowered apoptotic cell death and decreased matrix metalloproteinase and pro-inflammatory cytokine production. This resulted in reduced corneal inflammation as well as neovascularization and significantly accelerated corneal healing.
    Experimental Eye Research 10/2013; · 3.03 Impact Factor
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    ABSTRACT: The efficacy of a chemically modified dextran - heparan sulfate mimicking regenerating agent (RGTA) on the healing of the rabbit cornea injured with alkali was examined. The eyes were injured with 0.15 N NaOH applied on the cornea or with 1.0 N NaOH using a 8 mm diameter filter paper disk. Then RGTA or placebo was applied on the cornea. In the last group of rabbits, corneas injured with the high alkali concentration were left without any treatment for four weeks; subsequently, the corneas were treated with RGTA or placebo. The central corneal thickness was measured using a pachymeter. The corneas were examined morphologically, immunohistochemically and for real time-PCR. Compared to control (unaffected) corneas, following the application of low alkali concentration the expression of urokinase-type plasminogen activator, metalloproteinase 9, nitric oxide synthase and xanthine oxidase was increased in the injured corneal epithelium of placebo-treated eyes, whereas the expression of antioxidant enzymes was reduced. Nitrotyrosine and malondialdehyde stainings appeared in the corneal epithelium. RGTA application suppressed the antioxidant/prooxidant imbalance and reduced the expression of the above-mentioned immunohistochemical markers. The corneal thickness increased after alkali injury, decreased during corneal healing after RGTA treatment faster than after placebo application. Following the injury with the high alkali concentration, corneal inflammation and neovascularization were highly pronounced in placebo-treated corneas, whereas in RGTA-treated corneas they were significantly supressed. When RGTA or placebo application was started later after alkali injury and corneas were ulcerated, subsequent RGTA treatment healed the majority of them. In conclusion, RGTA facilitates the healing of injured corneas via a reduction of proteolytic, oxidative and nitrosative damage.
    Histology and histopathology 10/2013; · 2.28 Impact Factor
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    ABSTRACT: Solar UVB radiation evokes photokeratitis, accompanied by increased corneal hydration and changes in corneal transparency, resulting in increased light absorption. Corneal optical properties are disturbed and visual acuity decreased. The aim of this study was to investigate the reversibility of these UVB induced changes. Rabbit corneas were irradiated with UVB doses of 0.5 J/cm2 or 1.01 J/cm2 during four days. Some rabbits were sacrificed after the last irradiation and some two months later. Corneas were investigated spectrophotometrically for light absorption and corneal hydration was evaluated by central corneal thickness with an ultrasonic pachymeter. Corneal impression cytologies were examined immunohistochemically for proinflammatory cytokines and malondialdehyde. The increased corneal light absorption, hydration and the staining of immunohistochemical markers found in corneas after irradiation returned to normal values during two months in corneas irradiated with the lower UVB dose. In contrast, in corneas irradiated with the higher UVB dose, a moderate but statistically significant increase in corneal light absorption, hydration and positive immunohistochemical stainings remained as residual changes. This was in contrast to normal corneas, where the staining of proinflammatory cytokines as well as malondialdehyde was negative. In conclusion, the reversibility of UVB-induced disturbances was dependent on UVB dose. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.
    Photochemistry and Photobiology 10/2012; · 2.29 Impact Factor
  • Jitka Cejková, Cestmír Cejka, Jacques Luyckx
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    ABSTRACT: The UVB-irradiated cornea is damaged by oxidative stress. Toxic oxygen products induced by UVB radiation in the cornea are insufficiently removed by antioxidants, whose numbers decrease with increasing UVB irradiation. In addition, the UVB-irradiated cornea suffers from hypoxic conditions because damaged corneal cells cannot utilize oxygen normally, although the supply of oxygen to the cornea is unchanged (normal). This contributes to attenuated re-epithelialization, corneal neovascularization and apoptotic cell death. Our previous publications reported that trehalose applied on the corneal surface during irradiation significantly suppressed UVB-induced corneal oxidative damage. The results of this study provide for the first time important evidence that trehalose applied on the surface of corneas for two weeks following repeated UVB irradiation (312 nm, daily dose 0.5 J/cm2) accelerated corneal healing, restored corneal transparency and suppressed corneal neovascularization. Compared to buffered saline treatment, following which caspase-3, nitrotyrosine, malondialdehyde and urokinase-type plasminogen activator were still strongly expressed in the corneal epithelium two weeks after irradiation and corneal neovascularization was evident, apoptotic cell death was already significantly reduced after one week of trehalose application. The expression of other markers of injury returned to normal levels during two weeks of trehalose treatment. In conclusion, our results show that trehalose accelerated healing of the UVB irradiated cornea, very probably via suppression of hypoxia-response injury. In addition, immunohistochemical results on corneal cryostat sections corresponded with those obtained using corneal impression cytologies, thus confirming that corneal impression cytologies are useful for diagnostic purposes.
    Histology and histopathology 08/2012; 27(8):1029-40. · 2.28 Impact Factor
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    C Cejka, J Luyckx, J Cejková
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    ABSTRACT: UVB radiation from sunlight induces an acute corneal inflammation, photokeratitis, accompanied by changes in corneal hydration. We employed a method of ultrasonic pachymetry for daily examination of central corneal thickness as an index of corneal hydration of the rabbit cornea repeatedly irradiated by UVB radiation (312 nm, daily dose of 0.25 J/cm(2) during three or four days) as influenced by UVB absorber (actinoquinol combined with hyaluronic acid) dropped on the ocular surface during irradiation. One day after the third irradiation procedure the animals were sacrificed and corneas examined immuno-histochemically for peroxynitrite formation, a marker of oxidative damage, the antioxidant aldehyde dehydrogenase 3A1 and endothelial nitric oxide synthase, an enzyme generated nitric oxide. Results show that UV absorber combined with hyaluronic acid protected the cornea against UVB-induced changes in corneal thickness and microscopical disturbances to the cornea (both seen after buffered saline application) until the fourth experimental day. These UVB doses are equivalent to a daily exposure of 2.5 hrs of the human cornea to solar UVB radiation for three consecutive days. It is suggested that actinoquinol/ hyaluronic acid drops might be helpful for the human eye in the defence against photooxidative and other oxidative processes.
    Physiological research / Academia Scientiarum Bohemoslovaca 04/2012; 61(3):299-306. · 1.53 Impact Factor
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    ABSTRACT: Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight. Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm(2) or 0.5 J/cm(2) for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals. Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm(2) and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm(2). The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm(2). Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection.
    Current eye research 07/2011; 36(7):607-13. · 1.51 Impact Factor
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    ABSTRACT: Trehalose, a nonreducing disaccharide of glucose, is synthesized as a stress response factor when cells are exposed to stressful conditions. In the cornea, oxidative stress plays the key role in the development of acute corneal inflammatory response to UVB rays, photokeratitis. We found previously that trehalose reduced UVB-induced oxidative effects on the formation of cytotoxic peroxynitrite, apoptotic corneal epithelial cell death and changes in corneal optics. The aim of the present study was to examine whether trehalose might inhibit UVB-mediated proinflammatory cytokine and matrix metalloproteinase induction and the development of an antioxidant/pro-oxidant imbalance in the corneal epithelium, changes found previously to be strongly involved in the acute corneal UVB-induced inflammation. The expression of heat shock protein 70 as a potential biomarker for corneal UVB-induced damage was also examined. The corneas of New Zealand white rabbits were irradiated with UVB rays, 312 nm, daily dose of 0.5 J/cm(2) for 4 days. During the irradiation, trehalose drops were applied on the right eye and buffered saline on the left eye. One day after the end of irradiations, the animals were killed and the corneas examined immunohistochemically for the expression of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), pro-oxidant xanthine oxidoreductase/xanthine oxidase, proinflammatory cytokines (interleukin-6, interleukin-8), matrix metalloproteinase-9 and heat shock protein 70. After buffered saline treatment during UVB irradiation, an antioxidant/pro-oxidant imbalance appeared in the corneal epithelium: The expression of antioxidant enzymes was highly reduced, whereas the expression of pro-oxidant xanthine oxidase was increased. The pronounced expression of pro-inflammatory cytokines, matrix metalloproteinase and heat shock protein 70 was found in the UVB-irradiated corneal epithelium. Trehalose application significantly suppressed all the above-mentioned UVB-induced corneal disturbances. Trehalose favorably influenced the oxidative damage of the cornea caused by UVB rays. Trehalose suppressed proinflammatory cytokine induction. It is suggested that suppression of proinflammatory cytokines contributed strongly to reduced matrix metalloproteinase and xanthine oxidase expression in the UVB-irradiated corneal epithelium and to the decreased development of an antioxidant/pro-oxidant imbalance. The overexpression of heat shock protein 70 found in UVB-irradiated cornea after buffered saline treatment was reduced after trehalose application.
    Albrecht von Graæes Archiv für Ophthalmologie 04/2011; 249(8):1185-94. · 1.93 Impact Factor
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    ABSTRACT: 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. 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. 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. 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.
    Albrecht von Graæes Archiv für Ophthalmologie 12/2010; 248(12):1749-56. · 1.93 Impact Factor
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    ABSTRACT: Trehalose, a nonreducing disaccharide of glucose, produced and stored in many lower and higher organisms, although not in mammals, is synthetized as a stress responsive factor when cells are exposed to various environmental stress conditions. Recently, trehalose has been implicated in various situations in mammals. The aim of this paper was to examine whether trehalose might decrease the damage of the rabbit cornea evoked by UVB rays. During irradiation with UVB rays, consisiting of a daily dose of 0.5 J/cm2 for four days, trehalose was applied in eye drops on the right eye and buffered saline on the left eye. One day after the end of irradiation the animals were sacrificed and the corneas examined spectrophotometrically for light absorption. Another group of corneas similarly treated were examined morphologically and immunohistochemically. Corneal thickness (hydration) was measured using a Pachymeter. The results show that compared to buffered saline, trehalose treated corneas displayed fewer corneal disturbances during UVB irradiation. The increases in corneal hydration and light absorption were less pronounced and intracorneal inflammation and corneal neovascularization were suppressed. Nitric oxide synthases that generate nitric oxide were less expressed in the cornea, and formation of cytotoxic peroxynitrite (demonstrated by nitrotyrosine residues) was decreased. The expression of the antioxidant aldehyde dehydrogenase3A1 was less inhibited in the corneal epithelium, and apoptotic corneal epithelial cell death (detected by immunostaining for active caspase-3) was greatly diminished. In conclusion, trehalose reduced UVB-induced damage caused by reactive oxygen and nitrogen species and decreased changes in the corneal optics.
    Histology and histopathology 11/2010; 25(11):1403-16. · 2.28 Impact Factor
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    ABSTRACT: Ozone depletion leads to an increase in UV rays of solar radiation reaching the surface of the Earth which is harmful to biological systems. Of the eye, the cornea is directly open to increased amount of UV rays of which mainly UVB rays are capable to induce reactive oxygen species damaging the cells. Previous studies showed that the irradiation of the cornea with UVB rays leads to morphological as well as metabolic disturbances of the cornea. Also, corneal hydration and corneal light absorption are increased after UVB rays. These changes were observed after five days of repeated irradiation of the cornea with UVB rays. The aim of the present paper was to examine how early the changes of corneal hydration and light absorption occur after UVB irradiation. The rabbit corneas were irradiated with UVB rays for one, two, three or four days. Corneal light absorption was examined spectrophotometrically and corneal hydration measured by pachymeter (as corneal thickness). Results show that changes of corneal hydration and light absorption appear early after UVB irradiation and increase along with the number of irradiations. In conclusion, irradiation of the rabbit cornea with UVB rays leads to harmful changes of its optical properties.
    Physiological research / Academia Scientiarum Bohemoslovaca 11/2009; 59(4):591-7. · 1.53 Impact Factor
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    ABSTRACT: Autoimmune dry eye (Sjögren's syndrome, SS) is a chronic systemic disease characterized by salivary and lacrimal gland inflammation and tissue damage leading to keratoconjunctivitis sicca and xerostomia. In this review attention has been devoted to the cause of the development of oxidative injuries of the ocular surface of patients suffering from SS. It was shown that lacrimal glands and diseased conjunctival epithelium reveal increased expression of pro-inflammatory cytokines which are released into the tear fluid. A high amount of pro-inflammatory cytokines highly induce the elevated expression and activity of enzymatic systems that generate reactive oxygen and nitrogen species. An abundant amount of these toxic products leads to a decrease in antioxidants and to the formation of cytotoxic related oxidants, such as peroxynitrite. All these factors, together with reactive oxygen species from polymorphonuclear leukocytes, contribute to the development of oxidative injuries at the ocular surface. From the clinical point of view it is important that the level of severity of the above described microscopical disturbances found in conjunctival epithelial cells goes parallel with the level of severity of dry eye symptoms.
    Histology and histopathology 11/2009; 24(10):1357-65. · 2.28 Impact Factor
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    ABSTRACT: Previous studies have described elevated lipid peroxidase, myeloperoxidase and xanthine oxidoreductase/xanthine oxidase levels on the ocular surface of patients suffering from autoimmune dry eye (Sjögren's syndrome, SS). Reactive oxygen species generated by various enzymatic systems may be dangerous to the eye if they are not sufficiently cleaved by antioxidants. Because antioxidants have not been investigated in dry eye, the aim of this study was to examine the expression of antioxidant enzymes that cleave reactive oxygen species and play a key role in antioxidant protection. Conjunctival epithelial cells of dry eye (SS) patients were obtained by the method of impression cytology using Millicell membranes. Normal eyes served as controls. In the conjunctival epithelium superoxide dismutase, catalase and glutathione peroxidase were examined immunohistochemically. The enzyme expression levels were determined by image analysis and statistical evaluation. In contrast to normal eyes, where antioxidant enzymes were highly expressed in the conjunctival epithelium, in dry eye their expression was much less pronounced in correlation with the increasing severity of dry eye symptoms. Our study suggests that the decreased expression of antioxidant enzymes in dry eye disease (SS) contributes to the development of anterior eye surface oxidative injuries.
    Histology and histopathology 01/2009; 23(12):1477-83. · 2.28 Impact Factor
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    ABSTRACT: The aim of the present paper was to examine the irradiation effect of two doses of UVA rays (365 nm) on the rabbit cornea and lens. Corneas of anesthetized adult albino rabbits were irradiated with UVA rays for 5 days (daily dose 1.01 J cm(-2) in one group of rabbits and daily dose 2.02 J cm(-2) in the second group of animals). The third day after the last irradiation, the rabbits were killed, and their eyes were employed for spectrophotometrical, biochemical and immunohistochemical investigations. Normal eyes served as controls. Absorption spectra of the whole corneal centers were recorded over the UV-VIS (visible) spectral range. Levels of antioxidant and prooxidant enzymes, nitric oxide synthases and nitric oxide (indirectly measured as nitrate concentration) were investigated in the cornea. Malondialdehyde, a byproduct of lipid peroxidation, was examined in the cornea and lens. The results show that the staining for endothelial nitric oxide synthase was more pronounced in corneas irradiated with the higher UVA dose. Otherwise, UVA rays at either dose did not significantly change corneal light absorption properties and did not cause statistically significant metabolic changes in the cornea or lens. In conclusion, UVA rays at the employed doses did not evoke harmful effects in the cornea or lens.
    Photochemistry and Photobiology 01/2009; 85(3):794-800. · 2.29 Impact Factor
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    ABSTRACT: Previous papers examined lipid peroxidase levels and myeloperoxidase activity as products of oxidative and inflammatory reactions in the tear fluid of patients suffering from dry eye. The aim of the present paper was to investigate whether the enzymes xanthine oxidoreductase/xanthine oxidase known to generate reactive oxygen species contribute to oxidative reactions on the ocular surface. Xanthine oxidoreductase/xanthine oxidase were examined immunohistochemically as well as histochemically in conjunctival epithelial cells of patients suffering from dry eye. Patients with verified autoimmune dry eye (Sjögren's syndrome) participated in our study; normal eyes served as controls. Conjunctival epithelial cells were obtained by the method of impression cytology using Millicell membranes. The results revealed a pronounced expression, as well as activity of xanthine oxidoreductase/xanthine oxidase in the conjunctival epithelium of dry eye. It is suggested that reactive oxygen species which are generated by this enzymatic system, contribute to oxidative reactions on the eye surface of patients with ocular manifestations of autoimmune disease (Sjögren's syndrome).
    Histology and histopathology 10/2007; 22(9):997-1003. · 2.28 Impact Factor
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    ABSTRACT: Until now, the expression and possible role of nitric oxide and nitrogen related oxidants in the human dry eye have not been investigated. Therefore, we examined immunohistochemically nitric oxide synthase isomers (NOS), enzymes generated nitric oxide, nitrotyrosine, a cytotoxic byproduct of nitric oxide and malondialdehyde, a byproduct of lipid peroxidation, in conjunctival epithelium of patients with dry eye, Sjögren's syndrome (SS). Moreover, in conjunctival epithelium of patients with dry eye (SS) the immunohistochemical staining of some pro-inflammatory cytokines was demonstrated: mature interleukin-1 beta (IL-1beta), interleukin 6 (IL-6), interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha). Conjunctival epithelial cells were obtained by the method of impression cytology. Normal eyes served as controls. In contrast to the normal eyes where endothelial nitric oxide synthase (NOS3) as well as inducible nitric oxide synthase (NOS2) were only slightly expressed in conjunctival epithelium, in dry eye both NOS (mainly NOS2) were gradually expressed along the severity of dry eye symptoms which was in accord with pro-inflammatory cytokine immunodetection (IL-1beta, IL-6, IL-8, TNF-alpha) in dry eye conjunctival cytology samples. This was in contrast to normal eyes where the staining of pro-inflammatory cytokines was weak or completely absent. Peroxynitrite formation (demonstrated by nitrotyrosine residues) and lipid peroxidation (evaluated by increased malondialdehyde staining) were also found in conjunctival epithelium of dry eye with highly pronounced symptoms of dryness. In conclusion, results point to the suggestion that reactive nitrogen species are involved in the pathogenesis or self-propagation of autoimmune dry eye (SS).
    Nitric Oxide 09/2007; 17(1):10-7. · 3.27 Impact Factor
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    ABSTRACT: Under normal conditions, antioxidants at the corneal surface are balanced with the production of reactive oxygen species without any toxic effects. Danger from oxidative stress appears when natural antioxidants are overwhelmed leading to antioxidant/prooxidant imbalance. The aim of the present study was to examine the activities of enzymes contributing to the antioxidant/prooxidant balance in normal corneal epithelium of various mammals. The enzyme activities of antioxidant superoxide dismutase and glutathione peroxidase, as well as prooxidant xanthine oxidoreductase/xanthine oxidase were examined using biochemical methods. Results show that superoxide dismutase activity is high in rabbits and guinea pigs, whereas in pigs the activity is low and in cows it is nearly absent. In contrast, glutathione peroxidase activity is high in cows, pigs and rabbits, whereas in guinea pigs the activity is low. As far as prooxidant enzymes are concerned, elevated xanthine oxidoreductase/xanthine oxidase activities were found in rabbits, lower activities in guinea pigs, very low activity in cows and no activity in pigs. In conclusion, the above results demonstrate inter-species variations in activities of enzymes participating in antioxidant/prooxidant balance in the corneal epithelium. It is suggested that the levels of antioxidant and prooxidant enzymes studied in the corneal epithelium might be associated with the diurnal or nocturnal activity of animals. UV rays decompose hydrogen peroxide to damaging hydroxyl radicals and perhaps for this reason large animals with diurnal activity (cow, pig) require more effective peroxide removal (high glutathione peroxidase activity) together with the suppression of peroxide production (low superoxide dismutase activity, low xanthine oxidoreductase activity).
    Physiological research / Academia Scientiarum Bohemoslovaca 02/2007; 56(1):105-12. · 1.53 Impact Factor
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    ABSTRACT: Under normal conditions, the cornea absorbs the majority of UVB (ultraviolet B, 280-320 nm) rays, which is very important for the protection of the inner eye against their damaging effect. Our previous studies have shown that repeated irradiation of the rabbit cornea with UVB rays for 5 days (daily dose of 1.01 J cm(- 2)) caused photokeratitis accompanied by swelling (hydration) of the corneal stroma, thinning of the corneal epithelium and decrease in antioxidants. The purpose of this study was to examine the light absorption properties of such damaged rabbit cornea. Results of both spectrophotometry of the whole corneal buttons and corneal tissue dissolved in sodium hydroxide show that because of above mentioned disturbances, UVB-irradiated cornea absorbs more light throughout the whole measurable UV-VIS spectral range than the normal cornea. Increased corneal thickness (result of hydration), changes of corneal transparency (the cornea becomes grayish) and some increase in protein content all contribute to the increased light absorption of UVB irradiated corneas. We suggest that the UVB-irradiated cornea, although damaged and nearly without antioxidants, might actually through its higher UV absorbance protect the inner eye against further damage from UVB rays.
    Photochemistry and Photobiology 01/2007; 83(3):652-7. · 2.29 Impact Factor
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    ABSTRACT: Until now, the role of nitric oxide (NO) in cornea irradiated with UVB rays remains unknown. Therefore, we investigated nitric oxide synthase isomers (NOS), enzymes that generate NO, nitrotyrosine (NT), a cytotoxic byproduct of NO, and malondialdehyde (MDA), a byproduct of lipid peroxidation, in rabbit corneas repeatedly irradiated with UVB rays (312 nm, 1x daily for 6 days, the dose per day 1.01 J/cm2) using immunohistochemical methods. The biochemical measurement of nitrite and nitrate has been used for the indirect investigation of NO concentration in the aqueous humor. Results show that in contrast to normal corneas, where of the NOS isomers only endothelial nitric oxide synthase (NOS3) was expressed in a significant amount (in the epithelium and endothelium), in irradiated corneas all NOS isomers (also brain nitric oxide synthase, NOS1, and inducible nitric oxide synthase, NOS2) as well as an indirect measure of ONOO-formation and MDA were gradually expressed, first in the epithelium, the endothelium and the keratocytes beneath the epithelium and finally in the cells of all corneal layers and the inflammatory cells that invaded the corneal stroma. This was accompanied by an elevated concentration of NO in the aqueous humor. In conclusion, repeated irradiation with UVB rays evoked the stimulation of NO production, peroxynitrite formation (demonstrated by NT residues) and lipid peroxidation (evaluated by MDA staining).
    Histology and histopathology 05/2005; 20(2):467-73. · 2.28 Impact Factor
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    ABSTRACT: The purpose of the present study was to test our hypothesis that amiloride, a specific u-PA inhibitor, effectively decreases u-PA activity in cornea as well as in tear fluid and favourably affects corneal healing. Therefore, comparative histochemical and biochemical studies of u-PA and the effects of amiloride were performed on rabbit corneas and tear fluid using the sensitive fluorogenic substrate Z-Gly-Gly-Arg-7-amino-4-trifluoromethylcoumarin. Rabbit eyes were repeatedly irradiated with UVB for 9 days and during the irradiation topically treated with amiloride (1 mg/ml saline) or placebo (saline) (dropwise, 5 times daily). Results show that in placebo-treated eyes, UVB evoked the appearance of u-PA activity in cornea and tear fluid in early stages of irradiation, and u-PA levels increased during irradiation. Corneal epithelium was gradually lost and remnants of the epithelium as well as keratocytes in the upper part of corneal stroma showed high u-PA activity. Finally, corneas lost their epithelium completely. In corneal stroma, numerous u-PA-containing inflammatory cells were present. Corneas were vascularized. When amiloride was dropped on the eye surface on the first day of irradiation and subsequently daily until the end of the experiment, u-PA activity in both cornea and tear fluid was strongly inhibited. Corneas were covered with a continuous epithelium until the end of the experiment. The number of inflammatory cells was significantly decreased. Corneal vascularization was reduced by 50%. In conclusion, early application of amiloride inhibited u-PA activity in UVB-irradiated corneas as well as in tear fluid and diminished the development of corneal pathology.
    Acta Histochemica 02/2005; 107(1):77-86. · 1.61 Impact Factor

Publication Stats

115 Citations
46.95 Total Impact Points

Institutions

  • 2012
    • The Police Academy of the Czech Republic in Prague
      Praha, Praha, Czech Republic
  • 2009–2012
    • Academy of Sciences of the Czech Republic
      • • Ústav experimentální medicíny
      • • Laboratoř histochemie a farmakologie oka
      Praha, Hlavni mesto Praha, Czech Republic