agórski Z

Early electroretinographic features of streptozotocin-induced diabetic retinopathy

Background:  This study set out to document the early electrophysiological and immunohistochemical changes that occur in the retina of experimentally induced diabetic rats.

Alterations of kynurenic acid content in the retina in response to retinal ganglion cell damage.

The present study is the first to examine the modulation of retinal kynurenic acid (KYNA) content in response to N-methyl-D-aspartate (NMDA)-induced cell death in adult rat retinal ganglion cells (RGC). Adult Brown Norway rats were intravitreally injected with NMDA or PBS. Surviving RGC were retrogradely labeled with fluorogold and counted in wholemounts of retinas 2, 7 and 14 days after injection. Retinal KYNA content was measured by HPLC at the same time points. RGC numbers decreased significantly 2, 7 and 14 days after NMDA injection if compared to control retinas. KYNA concentration increased significantly two days after NMDA-injection. However, 7 and 14 days after injection retinal KYNA content was found markedly decreased in NMDA-treated eyes as compared to controls. It is conceivable that KYNA deficiency is causally related to the pathology of excitotoxic retinal diseases.

Reaction time during semi‐automated kinetic perimetry (SKP) in patients with advanced visual field loss

Purpose:  This study aimed to evaluate reaction time (RT) in patients with advanced visual field (VF) loss using semi‐automated kinetic perimetry (SKP).

Presence of kynurenic acid and kynurenine aminotransferases in the inner retina

Kynurenine aminotransferases (KATs I and II) are pivotal to the synthesis of kynurenic acid (KYNA), the only known endogenous glutamate receptor antagonist and neuroprotectant. This study is the first to identify KYNA in the rat retina and to examine immunohistochemically the distribution of KAT isoforms. As determined by HPLC, KYNA concentration in the retina was 99.9 ± 24.6 pmol/g wet wt. Immunohisto- chemical experiments showed that both KATs were present in the retina. KAT I was preferentially localised on Müller cell endfeet while KAT II was expressed in cells within the ganglion cell layer. In conclusion, KYNA is present and synthesised in the inner retina. This may suggest a modulatory role in glutamate-mediated retinal neurotransmission.

Efficacy and safety of indomethacin 0.1% eye drops compared with ketorolac 0.5% eye drops in the management of ocular inflammation after cataract surgery

Purpose:  To determine whether indomethacin 0.1% eye drops are at least as effective as ketorolac 0.5% eye drops in treating ocular inflammation following cataract surgery.

Elevated Concentrations of Kynurenic Acid, a Tryptophan Derivative, in Dense Nuclear Cataracts

Purpose: Kynurenines and their glycoside derivatives in the ocular lens absorb ultraviolet radiation and thus possibly help protect the retina from ultraviolet light. The current study analysed kynurenine aminotransferase I (KAT I) activity and kynurenic acid (KYNA) concentrations in human senile cataractous lenses and in experimentally induced cataracts in diabetic rats treated with streptozotocin (STZ). Methods: KYNA levels and KAT I activity were investigated with HPLC and detected fluorimetrically in the nuclei of 91 human cataractous lenses collected during planned extracapsular extraction. The lenses were classified on the Lens Opacity Classification System III scale and compared with clear lenses regarding KYNA concentrations. Cataractous lenses from STZ-treated rats were compared with control lenses. Results: KYNA concentration was 0.95 ± 0.22 in human NC0 (nuclear color) control lenses, 0.8 ± 0.72 in NC1, 1.18 ± 0.88 in NC2, 1.31 ± 0.70 in NC3, 1.78 ± 0.92 in NC4, 8.80 ± 8.28 (p < 0.05 vs. NC0) in NC5, and 14.0 ± 11.1 (p < 0.05 vs. NC0) in NC6. A correlation was found between KYNA concentrations and the grade of cataract (r = 0.047, p < 0.001). KAT I activity in human cataracts was 0.44 ± 0.16 pmol/mg protein− 1 hr− 1. Elevated KYNA concentrations in rat cataractous lenses were also observed (p < 0.05). Conclusions: KYNA levels are elevated in senile nuclear human cataracts and in cataractous lenses of rats with experimentally induced diabetes.

Comparison of static automated perimetry and semi-automated kinetic perimetry in patients with bilateral visible optic nerve head drusen

Purpose:  Until now there has been no standardized, systemic approach to diagnostics in patients with optic nerve head drusen (ONHD). This study compares visual field (VF) results obtained with static automated perimetry (SAP) and semi‐automated kinetic perimetry (SKP) in patients with bilateral visible ONHD.

Content of Kynurenic Acid and Activity of Kynurenine Aminotransferases in Mammalian Eyes

The present study investigated the kynurenic acid (KYNA) contents and kynurenine aminotransferase (KAT I and II) activity in structures of the human, monkey, rabbit and bovine eye. KYNA levels were investigated with HPLC and detected fluorimetrically. The activity of KAT I and II was assayed as quantitative analysis of newly synthesized KYNA in vitro. Mean KYNA levels (±SD) in the human retina and vitreous body were 36.8 ± 7.6 and 33.1 ± 6.2 pmol/g wet tissue weight, respectively. In human eyes, KAT I activity in the vitreous body was 0.57 ± 0.28, that of KAT II was 2.56 ± 0.69. KAT I activity in the retina was 3.42 ± 1.17 and that of KAT II 10.75 ± 9.2. (KAT activity is expressed as KYNA synthesis in picomoles per gram wet tissue weight per hour.) The values of KYNA and KAT observed in other mammalian species tested were in the same range. In conclusion, KYNA and KAT enzymatic activity are present in the structures of human and other mammalian eyes.

Occurrence of human papillomavirus in pterygia.

Purpose:  The aim of the study was to assess the occurrence of human papillomavirus (HPV) DNA in pterygium.

Age-dependent decrease of retinal kynurenate and kynurenine aminotransferases in DBA/2J mice, a model of ocular hypertension.

The study examines age-dependent changes of kynurenic acid (KYNA) content and kynurenine aminotransferases (KAT I and KAT II) celluar expression in the retinas of DBA/2J mice. Retinas were obtained from DBA/2J mice of different ages (3, 6 and 11 months). C57BL6 mice were used as controls. As measured with HPLC, KYNA content decreased (p < 0.01) in the retinas of 6-month-old DBA/2J mice and continued to decrease (p < 0.0074) in the retinas of 11-month-old animals compared to the controls. Immunohistochemistry showed that expression of both KAT I and KAT II decreased markedly in the retinas of 11-month-old DBA/2J mice compared to controls. The impairment in KYNA biosynthesis in the retinas of DBA/2J mice may be one of the mechanisms of retinal neurodegeneration related to ocular hypertension.