Huaqing Gong

Riboflavin Deficiency Induces Ocular Surface Damage

Purpose: To examine the conjunctiva and cornea of riboflavin-deficient rats with scanning (SEM) and transmission (TEM) electron microscopes. Materials and Methods: Three-week-old Wistar Kyoto rats were fed a riboflavin-deficient diet (0.05 mg riboflavin/100 g) for 3 months. As a recovery experiment, rats which had been on a riboflavin-deficient diet for 3 months were given water with 1 mg riboflavin/300 ml for 2 months. The conjunctiva and the cornea were examined with SEM and TEM. Results: The serum riboflavin level was significantly lower in the riboflavin-deficient group than in the controls. In rats on a riboflavin-deficient diet for 3 months, SEM showed decreased microvilli and microplicae in the superficial epithelium of the conjunctiva and a decrease in the number of goblet cells. The cornea showed many dark cells and a marked decrease of microvilli and microplicae. In the riboflavin-deficient rats, TEM of the conjunctiva showed a decrease of microvilli and microplicae in the most superficial epithelial cells, a decrease in the layers of the epithelium and a marked decrease in the number of goblet cells, while the cornea had decreased microvilli and microplicae in the superficial epithelium, dark wing cells, loss of the basement membrane and hemidesmosomes of basal cells, cell debris and degenerative stroma cells and deposits of dense bodies in the subepithelial layer of the stroma. In rats recovered from riboflavin deficiency, the conjunctiva and cornea showed no abnormalities. Discussion: Riboflavin plays a role in the development and maintenance of the surface structures of epithelial cells. Riboflavin may also be necessary for the development and maintenance of goblet cells. Conclusion: Riboflavin is essential for maintaining the structure and function of the ocular surface.

Role of apoptosis in eyelid development.

The upper and lower eyelids fuse together during development and then reseparate. The mechanism of reseparation of the eyelids is still unclear, although many reports agree that keratinization has a major role in lid separation. We applied apoptotic detection methods with ultrastructural features to examine the process of lid separation in rats. We confirmed that the eyelids fused on the 18th day of gestation. At this stage, cellular excrescences appeared from the external and conjunctival surfaces overlying the junctional zone, and the junctional zone consisted of epidermal cell clumps with wide intercellular spaces. From the 18th to the 20th day of gestation, many apoptotic cells appeared in the junctional zone and in the cellular excrescences. In these tissues, TUNEL-positive cells and immunohistochemically stained macrophages were found at this stage. We conclude that apoptosis may eliminate external and conjunctival cellular excrescences to make both surfaces smooth and continuous across the junctional zone. Apoptosis may also play a major role in providing space for proliferation of newly organized epidermal cells without wide intercellular spaces. Subsequent keratinization extends onto epidermal and conjunctival sides of the junctional zone until separation of the lids is complete.

Long-term effect on optic nerve of silicone oil tamponade in rabbits: histological and EDXA findings

Purpose Side-effects after intravitreal use of silicone oil (SO) are not well defined and elucidated. The object of this study was to examine the influence and toxicity of SO on the optic nerve after vitrectomy with SO tamponade.Methods We injected medical grade SO and emulsified SO into rabbit eyes after gas-mediated vitreous compression and examined the eyes by light microscopy (LM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDXA) (point analysis and area analysis) 6 months after injection. We compared the findings in the non-treated eyes and eyes with only gas-mediated vitreous compression with those in SO-injected eyes.Results Vacuole-like structures were seen in the optic nerve posterior to the lamina cribrosa. In the group treated with only gas-mediated vitreous compression, the myelin structures were shown by TEM to be destroyed and replaced by glial tissue, while in groups injected with medical grade or emulsified SO severe destruction of the myelin sheath (myelinolysis) was observed. Silicone was identified at the electron-dense edges of the vacuoles by EDXA point analysis, but not in the vacuoles without electron-dense deposits. Dots of Si K alpha were not seen in the control groups, and dense dots were observed in SO-injected groups, by EDXA area analysis.Conclusions Some of the vacuoles might be artefacts caused by insufficient fixation or the operative procedure, but TEM showed almost no artefacts in the control optic nerve. Thus, most vacuoles may be SO storage sites. SO uptake into the optic nerve might play a role in the pathogenesis of optic nerve atrophy after SO injection.

Ocular Surface in Zn-Deficient Rats

Purpose: We studied the cornea and conjunctiva of Zn-deficient rats with an electron microscope and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to elucidate the role of trace elements in the cornea and conjunctiva. Materials and Methods: Twenty-one-day-old Wistar Kyoto rats were fed a Zn-deficient diet and deionized water for 7 weeks and then killed. The control rats were fed a Zn-deficient diet and deionized water supplemented with 3 mg Zn/100 ml. After 7 weeks on the deficient diet, another group of rats was given drinking water containing 3 mg Zn/100 ml and the usual diet containing 4.7 mg Zn/100 g for 8 weeks for recovery. The cornea and conjunctiva were examined by electron microscopy and TOF-SIMS. Results: Microvilli and microplicae in the most superficial layer of the epithelium of the Zn-deficient rat conjunctiva and cornea were prominently reduced, and dark cells were significantly increased. The numbers of goblet cells were decreased in the conjunctiva of the Zn-deficient group. Zn, Ca and Al ions were significantly fewer, but K, Fe, Cl and S ions were significantly more numerous in the Zn-deficient group than in the control group. In the cornea of the Zn-deficient group, there was significantly more Cl but less Ca and vitamin C than in the controls. Discussion: Zn deficiency may interfere with protein, nucleic acid and collagen synthesis through the reduction of Zn-containing enzymes. Myosin-like substance, actin filaments and tonofibrils are important structural components for microvilli and microplicae in the epithelium. Maldevelopment of these structural components may be related to disturbed activities of Zn-containing enzymes in protein and collagen synthesis because of Zn deficiency. In addition, Zn deficiency caused changes in the levels of Zn and other trace elements such as Ca, Al, S, Fe, and Cl and vitamin C. Conclusion: Zn deficiency resulted in poorly developed microvilli and microplicae on the ocular surface tissues, reduced the number of goblet cells and changed the quantity of trace elements and vitamin C.

CORNEAL CHANGES IN MANGANESE-DEFICIENT RATS

PURPOSE This study was undertaken to examine the changes in the cornea due to dietary manganese (Mn) deficiency in Wistar-Kyoto rats, because there is a lack of information on the significance of manganese in the cornea. METHODS Mature female Wistar-Kyoto albino rats were mated with males. All pregnant females were divided into Mn-deficient and control groups. The offspring were fed a Mn-deficient diet. When they reached age 3 months, Mn-deficient females were mated with Mn-deficient males. The offspring of this second generation of Mn-deficient rats continued to be fed on the Mn-deficient diet and were used for the experiment. The corneas were examined at age 2 months. After 3 months on a Mn-deficient diet, the rats were given a normal diet for a 3-month recovery experiment. The corneas were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). RESULTS TEM revealed very few microvilli and bundles of tonofibrils and abnormal mitochondria in the corneal epithelium of Mn-deficient rats. The stroma was thin, and collagen fibers were decreased prominently in diameter. Descemets membrane was thinner than in the control group. SEM showed many fewer microvilli in the Mn-deficient rats and more dark cells in the most superficial layer of epithelium. SEM also showed endothelial cells with a pentagonal instead of a hexagonal shape in Mn-deficient rats. Rats fed a normal diet for 3 months after Mn deficiency showed a normal serum Mn level and almost normal corneal structure. CONCLUSION This study suggested that the cornea needs Mn for the maintenance of its cell structure.

Interaction of zinc and vitamin A on the ocular surface

Abstract Purpose. The purpose of this study was to assess morphologically the interaction between zinc and vitamin A in their effect on the ocular surface. Methods. Three-week-old Wistar Kyoto rats were divided into five groups: group A(+) Zn(+) was fed a diet containing both vitamin A and Zn; group A(–) was fed a vitamin A-deficient diet; group A(–) Zn(+) was given a vitamin A-deficient diet and deionized distilled water with Zn; group Zn(–) and group Zn(–) A(+) were fed a Zn-deficient diet, whereby group Zn(–) A(+) received an intraperitoneal injection of vitamin A. Corneas and conjunctivas of each group were examined by electron microscopy. Results. The corneas and conjunctivas of group A(–) demonstrated a decrease in the number of microvilli in the epithelium. The corneas and conjunctivas of group A(–) Zn(+) had a decrease in microvilli but more microvilli than those of group A(–). The corneas of group A(–) showed keratinization, but those of group A(–) Zn(+) showed no keratinization. In group Zn(–) the microvilli on the conjunctiva and cornea were sparse. Group Zn(–) A(+) had a decrease in microvilli but more microvilli than group Zn(–). The conjunctivas of group Zn(–) A(+) had more goblet cells with granules than did those of group Zn(–). Conclusion. These results suggest that a synergistic interaction exists between vitamin A and zinc for the maintenance of the corneal and conjunctival epithelium.

Ultrastructure of the Optic Nerve in Magnesium-Deficient Rats

Purpose: The ultrastructure of the optic nerves in magnesium (Mg)-deficient rats was studied to elucidate the function of Mg. Methods: After delivery, mother Wistar Kyoto rats were fed a low-Mg diet containing 0.1 mg Mg/100 g diet with all other nutrients and distilled and deionized water. Infant rats were suckled by their mothers for 21 days and then fed the same Mg-deficient diet. Control mother rats were fed commercial rat pellets containing 24 mg Mg/100 g diet and all other nutrients. The optic nerves were examined by electron microscopy at 6 weeks of age. Results: In the Mg-deficient rats, serum Mg levels were significantly lower and calcium levels higher than in the control rats. Ultrastructural findings were: significantly fewer myelinated axons and significantly thinner myelin sheaths in the Mg-deficient rats than in the control and pair-fed controls, and more numerous unmyelinated axons. There were multifocal areas of destruction and necrosis in the optic nerve of Mg-deficient rats. Conclusions: This study suggests that the optic nerve needs Mg for the development and maintenance of its cell structure.

Eosinophilic granuloma (Kimura’s disease) of the orbit: a case report

Abstract · Background: Eosinophilic granuloma of the soft tissue, Kimura’s disease, is a benign slow-growing tumor that is manifested clinically by one or more inflammatory nodules involving mainly the face and scalp, but rarely the eye. · Case report: The patient was a 32-year-old male with swelling of the left lower eyelid, marked peripheral blood eosinophilia and increased serum immunogloblin E. MRI revealed swelling of all rectus muscles of the left eye, but no tumor mass. Corticosteroid treatment reduced the swelling of the eyelid, but it recurred after corticosteroid was discontinued. Eight years later the patient returned with a complaint of increased swelling of the left lower eyelid. An elastic, nontender, soft tumor mass was palpable subcutaneously in the left lower eyelid extending into the orbit. MRI revealed a tumor mass in the left orbital space. The parotid gland was also swollen and palpable. Both tumors were resected surgically, and histopathological study revealed prominent proliferation of lymphoid follicles with germinal centers showing interfollicular infiltration by eosinophils. The pathological findings in the parotid gland were similar. The diagnosis was Kimura’s disease. · Conclusion: This patient is unique in that he had no tumor at the first examination, only swelling of the rectus muscles, and a tumor mass appeared many years later. Unilateral swelling of the rectus muscles may be one of the first signs of Kimura’s disease. Not only tumor but also swelling of the rectus muscles limited ocular movement.

Corneal changes in magnesium-deficient rats.

Purpose. The purpose of the current study is to investigate the cornea in magnesium (Mg) deficiency and elucidate the local function of trace elements. Methods. After delivery, mother Wistar Kyoto rats were fed a low Mg diet containing 0.1 mg Mg/100 g diet with all other nutrients and distilled and deionized water. Infant rats were suckled by their mothers for 21 days and then fed the same Mg-deficient diet. Control mother rats were fed commercial rat pellets containing 24 mg Mg/100 g diet and all other nutrients. The corneas were examined by electron microscopy at 6 weeks of age. Results. In the Mg-deficient rats, serum Mg levels were significantly lower and calcium (Ca) levels higher than in the control rats. The corneas of Mg-deficient rats showed decreased microvilli and microplicae in the epithelial cells of the most superficial layer, increased mitochondria with abnormal shapes in the basal cells in the epithelium, condensed chromatin in the nuclei of the basal cells, and high density deposits and macrophage-like cells in the subepithelium of the stroma. Mg-deficient rats had pentagonal and square endothelial cells. Conclusion. Since Mg2+ has biologic functions including structural stabilization of protein, nucleic acids, and cell membranes, Mg deficiency may induce changes in the corneal surface and nuclei of corneal epithelial and endothelial cells. These disturbances may interfere with protection from infections, foreign bodies, dryness, and direct exposure to air. Thus, Mg is essential for the cornea to maintain normal structure and function.

Changes of vitamins A and E in the rat retina under light and dark conditions detected with TOF-SIMS

Abstract Vitamin A is a key material for visual function and its metabolism is always important topics in visual sciences. TOF-SIMS (SIMS: secondary ion mass spectrometry) can detect organic materials and elements in relation to the cell and tissue. Changes of vitamin A distribution in the rat retina under light and dark adaptations were detected with TOF-SIMS. Vitamin A is present in combination with polyunsaturated fatty acids in the living cell. Vitamin E participates in the membrane stability. Thus we examined not only vitamin A, but also vitamin E. In light condition, vitamins A and E were increased in the photoreceptor cell. These findings suggest that these vitamins are increased in the light exposed retina.