Natalia Ziółkowska

Oculodermal melanocytosis (ODM) is an uncommon congenital melanocytic disorder infrequently reported in dogs. It is characterized by dermal and ocular hyperpigmentation involving neural crest-derived tissues and may predispose affected dogs to secondary ocular complications such as glaucoma or, in exceptional cases, malignant transformation. A 4-year-old neutered male Great Dane was presented with unilateral facial and ocular hyperpigmentation. Ophthalmic examination revealed marked pigmentation and thickening of the right iris, perilimbal and peripheral corneal pigmentation, and diffuse uveal involvement. Bilateral uveal cysts were identified. Intraocular pressure was within reference intervals but asymmetric between eyes. Fundus examination demonstrated focal tapetal hyperreflectivity and vascular attenuation in the right eye, and electroretinography confirmed reduced retinal function. Six months later, secondary glaucoma developed, necessitating enucleation. Histopathology revealed diffuse infiltration of heavily pigmented cells without cytologic atypia or mitotic activity within the sclera, uveal tract, perioptic connective tissue, and cornea. Marked goniodysgenesis was also identified, providing a structural basis for impaired aqueous outflow. This case expands the clinicopathologic characterization of canine oculodermal melanocytosis by documenting concurrent breed-associated uveal cysts and histologically confirmed goniodysgenesis in addition to retinal dysfunction and secondary glaucoma. The findings highlight the multifactorial nature of ocular disease in affected dog and emphasize that pigmentary disorders may coexist with independent structural abnormalities influencing intraocular pressure and retinal function. Comprehensive and repeated evaluation of both anterior and posterior segment structures is therefore essential when managing complex unilateral ocular pigmentation.

Sterile granuloma/pyogranuloma syndrome (SGPS) is an immune-mediated disease producing nodular and plaque-like skin lesions in dogs. Ocular involvement has

Light is a major environmental factor that regulates circadian rhythms and pineal melatonin synthesis. While the influence of nighttime light exposure on melatonin suppression has been extensively investigated, much less is known about the impact of photophase light wavelength on pineal function. The aim of the study was to determine the influence of monochromatic light during the photophase on diurnal changes in melatonin-related indoles in the rat pineal gland. Wistar rats were exposed for 7 days to 150 lx of monochromatic blue (463 ± 10 nm), green (523 ± 10 nm), or red (623 ± 10 nm) LED light, or to white fluorescent light (control), under a 12:12 light–dark cycle. Pineal glands were collected every 3 h over 24 h, and the indole content was analyzed by high-performance liquid chromatography. The results demonstrated that both the timing and course of N-acetylserotonin (NAS) and melatonin (MLT) rhythms were significantly affected by light wavelength. Blue light most effectively preserved the normal rhythmicity observed under full-spectrum white light, whereas green—and particularly red light—delayed nocturnal NAS and MLT synthesis. These changes were accompanied by concurrent alternations in rhythms of serotonin, its precursors, and metabolites. The data strongly suggest that spectral light composition during the photophase influences pineal indole metabolism via melanopsin-mediated phototransduction and possibly other retinal mechanisms. These findings may have implications for the design of artificial lighting environments in human life and animal housing.

Light is a major environmental factor that regulates circadian rhythms and pineal melatonin synthesis. While the effects of nighttime light exposure on melatonin suppression have been extensively studied, much less is known about the impact of photophase light wavelength on pineal function. This study aimed to evaluate the influence of monochromatic light during the photophase on diurnal changes in melatonin-related indoles in the rat pineal gland. Wistar rats were exposed for 7 days to 150 lx of monochromatic blue (463 ± 10 nm), green (523 ± 10 nm), or red (623 ± 10 nm) LED light, or to white fluorescent light (control), under a 12:12 light-dark cycle. Pineal glands were collected every 3 hours over 24 hours and the indole content was analyzed by high-performance liquid chromatography. The results showed that both the timing and course of N-acetylserotonin (NAS) and melatonin (MLT) rhythms were significantly affected by light wavelength. Blue light most effectively preserved the normal rhythmicity observed under full-spectrum white light, whereas green - and particularly red light - delayed nocturnal NAS and MLT synthesis. These changes were accompanied by concurrent alternations in rhythms of serotonin, its precursors and metabolites. The data strongly suggest that spectral light composition during the photophase influences pineal indole metabolism via melanopsin-mediated phototransduction and possibly other retinal mechanisms. These findings may have implications for the design of artificial lighting environments in human life and animal housing.

Objective: To describe the clinical and morphological features of a case of superficial nodular keratitis in a dog. Case Description: A German shepherd dog previously diagnosed with chronic superficial keratitis (CSK) presented with a nonpainful, unilateral corneal nodule. After a complete ophthalmic examination, topical treatment with dexamethasone (0.1% dexamethason, WZW) was prescribed. However, the patient did not respond to this treatment; thus, a superficial keratectomy was performed. The lesion was examined histologically and immunohistochemically. Results: The ophthalmic examination revealed a round, pink, solid nodule, approximately 0.5 cm in diameter, located in the ventral, paracentral cornea. Results from the Schirmer tear test I , tonometry, and fluorescein staining were in the normal ranges. A small amount of mucous discharge and moderate hyperemia of the bulbar conjunctiva were present. The histological examination revealed a solid mass in the superficial corneal stroma under the corneal epithelium. Hematoxylin and eosin (HE) staining showed that the mass was supplied with blood vessels; HE and immunohistochemistry revealed it consisted of a mixture of plasma cells (MUM ⁺ cells), B lymphocytes (CD79 ⁺ , CD20 ⁺ cells), T lymphocytes (CD3 ⁺ ), and macrophages (Iba1 ⁺ cells). Mitotic figures were absent. Some nuclei in inflammatory infiltrates displayed a Ki76 ⁺ reaction. Inflammatory infiltrates were present in the superficial stroma and the corneal epithelium. Conclusion: These novel results demonstrate that the features of nodular keratitis in a German shepherd dog previously diagnosed with CSK differ from the features of xanthogranulomas, nodular episcleritis, corneal granulomas, pyogranulomatous keratitis, corneal epithelial inclusion cysts, protozoal keratitis, and corneal squamous cell carcinoma.

This study investigated the effect of low-intensity blue light on the albino Wistar rat retina, including intrinsically photosensitive retinal ganglion cells (ipRGCs). Three groups of nine albino Wistar rats were used. One group was continuously exposed to blue light (150 lx) for 2 d (STE); one was exposed to 12 h of blue light and 12 h of darkness for 10 d (LTE); one was maintained in 12 h of white light (150 lx) and 12 h of darkness for 10 d (control). Melanopsin (Opn4) was immunolabelled on retinal whole-mounts. To count and measure Opn4-positive ipRGC somas and dendrites (including Sholl profiles), Neuron J was used. Retinal cryosections were immunolabeled for glial fibrillary acid protein (GFAP) and with terminal deoxynucleotidyl transferase dUTP nick-end labelling for apoptosis detection. LTE reduced the length of Opn4-positive ipRGC dendrites (p = 0.03) and decreased Opn4-immunoreactivity in ipRGC outer stratifying dendrites. LTE and STE decreased the complexity of dendritic arborization (Sholl profile; p < 0.001, p = 0.03, respectively), increased retinal GFAP immunoreactivity (p < 0.001, p = 0.002, respectively), and caused outer segment vesiculation and outer nuclear layer apoptosis. Ultrastructural analysis showed that LTE damaged mitochondria in retinal ganglion cells and in the inner plexiform layer. Thus, LTE to low-intensity blue light harms the retinas of albino Wistar rats.

The European beaver is a herbivorous rodent whose diet changes seasonally, and in winter consists of large quantities of woody plants. It is distinguished among other mammals by a unique organization of the stomach that comprises the cardiogastric gland and by the unusual process of mucus formation in the gastric mucosa. The aim of study was to (i) characterize the structure of the beaver esophagus with particular attention to the mucosal epithelium; (ii) compare the histological structure of the esophagi collected in spring, summer, and winter; (iii) provide preliminary data on the structure of the esophagus in beaver fetuses. The study was conducted on esophagi of 18 adult beavers captured in Poland in April, August, and December, and on 3 fetal organs. The results obtained in adults show that the mucosa is lined with thick stratified squamous keratinized epithelium with a structure similar to that of the skin epidermis. Ultrastructural studies reveal the presence of multiple lamellar and non-lamellar bodies in granular cells, whose morphology and location gradually change while reaching the upper epithelial layers. The muscularis mucosa comprises a layer of longitudinally oriented bundles of smooth muscle cells. Both mucosa and submucosa do not comprise any glands. The thick muscularis externa consists mainly of internal circular and external longitudinal layers of striated muscle fibers. The keratinized layer of mucosa epithelium was 2-3-fold thicker in esophagi collected in winter than in those collected in spring and summer, while the epithelial cell layer thickness remained unchanged regardless of the season. Immunolabeling for proliferating cell nuclear antigen shows a higher index of epithelium proliferation in esophagi collected in winter than in spring and summer. No seasonal differences were noted in other layers of the esophagus. Fetal organs have epithelium covered with a keratinized layer, thinner than in adults, and the muscularis externa comprises both striated and smooth muscle cells.

Despite concern over potential retinal damage linked to exposure to light-emitting-diode (LED) light (particularly blue light), it remains unknown how exposure to low-intensity monochromatic LED light affects the expression of rhodopsin (Rho, a photopigment that mediates light-induced retinal degeneration), melanopsin (Opn4, a blue-light sensitive photopigment), c-Fos (associated with retinal damage/degeneration), and Birc5 (anti-apoptotic). This study investigated the mRNA expression profiles of these genes under exposure to white and monochromatic light (blue, red, green) in the retinas of albino rats under a cycle of 12 h of light and 12 h of darkness. In each group, 32 Wistar rats were exposed to one type of monochromatic-LED or white-fluorescent light for 7 day (150 lx). Retinal samples were taken for qPCR analysis and light and electron microscopy. Blue and green light exposure markedly decreased expression of Rho and Opn4 mRNA and increased expression of Birc5 and c-Fos mRNA (P < 0.05). In retinas from the blue-light group, loss and vesiculation of photoreceptor outer segments were visible, but not in retinas from the red-light and control group. Measurements of the photoreceptor inner and outer segments length revealed, that this length was significantly decreased in the blue- and green-light exposure groups (P < 0.02), but not in the red-light exposure group. Increased expression of Birc5 and decreased expression of Rho and Opn4 after exposure to blue and green light may be early responses that help to reduce light-induced retinal damage.

Purpose: The purpose of this study was to investigative the effects of blue light on intrinsically photoreceptive retinal ganglion cells (ipRGCs). Methods: Brown Norway rats were used. Nine rats were continuously exposed to blue light (light emitting diodes [LEDs]: 463 nm; 1000 lx) for 2 days (acute exposure [AE]); 9 rats were exposed to 12 hours of blue light and 12 hours of darkness for 10 days (long-term exposure [LTE]); 6 control rats were exposed to 12 hours of white fluorescent light (1000 lx) and 12 hours of darkness for 10 days. Whole-mount retinas were immunolabelled with melanopsin antibodies; melanopsin-positive (MP) ipRGC somas and processes were counted and measured with Neuron J. To detect apoptosis, retinal cryo-sections were stained with terminal deoxynucleotidyl transferase dUTP nick-end labeling. Ultra-thin sections were visualized with transmission electron microscopy. Results: The number of MP ipRGC somas was significantly lower in retinas from AE and LTE rats than in those from control rats (P < 0.001 and = 0.002, respectively). The mean length of MP areas of processes was significantly lower in AE rats (P < 0.001). AE rats had severe retinal damage and massive apoptosis in the outer nuclear layer; their mitochondria were damaged in the axons and dendrites of the nerve fiber layer and the inner plexiform layer. Retinal ganglion cells (RGCs) in AE rats appeared to have reduced amounts of free ribosomes and rough endoplasmic reticulum. Conclusions: AE to blue light reduces melanopsin expression and damages RGCs, likely including ipRGCs. Changes in the axons and dendrites of RGCs suggest possible disruption of intraretinal and extraretinal signal transmission.

This study determined the effect of norepinephrine and light exposure on melatonin secretion in goose pineal explants. Additionally, it investigated changes in the content of norepinephrine, dopamine, and their metabolites [3,4-dihydroxyphenylacetic acid; vanillylmandelic acid (VMA); homovanillic acid] in goose pineal glands in vivo under 12 h of light and 12 h of darkness (LD), a reversed cycle (DL), constant light (LL), and constant darkness (DD). In vitro content of melatonin was measured by radioimmunoassay; contents of catecholamines and their metabolites were measured by high-performance liquid chromatography. Exposure of pineal explants to LD or DL established rhythmic melatonin secretion; this rhythm was much better entrained with norepinephrine exposure during photophase than without it. When the explants were kept in LL or DD, the rhythm was abolished, unless NE was administered during natural scotophase of a daily cycle. In vivo, norepinephrine and dopamine levels did not display rhythmic changes, but their respective metabolites, HMV and VMA, displayed well-entrained diurnal rhythms. These results indicate that norepinephrine and sympathetic innervation play key roles in regulation of pineal secretory activity in geese, and that pineal levels of VMA and HMV provide precise information about the activity of sympathetic nerve fibers in goose pineal glands.