Objective: To observe the morphological changes of the retina at early stage of streptozotocin (STZ)-induced diabetes mellitus (DM) model, so as to assess the feasibility of using STZ-induced DM as an animal model of early diabetic retinopathy (DR). Methods: Sixty-four male SD rats (body weight [180±20] g) were randomly divided into the CON and DM groups (n=32). Rats in DM group received intraperitoneal injection of 1% STZ once and those in the CON group were given same volume of citrate buffer in the same manner. The average body weight and blood glucose were similar in the two groups before intraperitoneal injection. The blood glucose, body weight, and other parameters were determined once a week after intraperitoneal injection. In the 10 th week, the morphological changes of the retina were observed by H-E staining, stretched preparation of FITC-dextran perfused retinal blood vessels, and transmission electron microscopy in randomly chosen samples. Results: The successful rate of STZ-induced DM model was 100%. The body weight of animals in DM group had no obvious increase after injection, and it even decreased at late stage. The body weight increased gradually in the CON group. The average body weight of DM group ([169.9±26.9] g) was significantly lower than that of the CON group ([439.2±23.5] g) in the 10th week (P<0.001). The average blood glucose of DM group ([26.63±4.54] mmol/L) was significantly higher than that of the CON group ([6.37±0.49] mmol/L) 72 h after injection (P<0.001). DM group had a blood glucose > 16.7 mmol/L and CON group had a blood glucose of 5.6-7.4 mmol/L throughout the 10 weeks. Retina H-E staining showed retinal capillary dilatation and interstitial edema in DM group in the 10th week, and the CON group had no obvious abnormalities. Stretched preparation of FITC-Dextran perfused retinal blood vessels showed vascular tortuosity and caliber irregularity in the DM group, but with no leakage, microvascular tumor or retinal non-perfusion area. The retinal vessel diameter was uniform and the branching was natural and smooth in the CON group. TEM results showed the following retinal ultrastructural changes in the DM group: thicker capillary basement membrane, digitation of capillary endothelial cells, mitochondrial swelling, cristae disruption, and vacuolar degeneration in capillary endothelial cells, bipolar cells and ganglion cells, mitochondrial swelling and cristae disruption in pericytes, decreased membranous disc (photoreceptor cell's outer segment), and widened gap between membranous discs. Conclusion: The retina morphological changes of early stage background diabetic retinopathy (BDR) can be found in the 10th week after STZ injection in rats, and STZ-induced DR model can be used as an early stage DR model; besides, the method is simple, economical, quick, with good reproducibility and high successful rate.

Objective: To prepare fluorouracil-loaded chitosan nanoparticle (5-Fu-CS-NP) for ophthalmologic usage and evaluate its releasing characteristics in vitro. Methods: 5-Fu-CS-NP was prepared with 5-Fu, polyacrylic acid and chitosan using dispersion method. The mean size, entrapment efficiency (EE%), drug loading (DL%) and the in vitro releasing characteristics of 5-Fu-CS-NP were investigated. Results and conclusion: The mean size of 5-Fu-CS-NP was (144.6±3.1) nm, the EE% was 84.5% and the DL% was 3.91%. 5-Fu-CS-NP had a satisfactory sustained-releasing effect and the releasing could last for 3-7 days, and the release behavior was not greatly changed within a pH value of 7.2-7.4.

Objective: To investigate the variation of visual acuity (VA) at different contrast levels under bright and dark backgrounds in healthy adults. Methods: Fifty-four men (108 eyes) with normal VA were enrolled in this study. LogMAR VA was measured at 4 contrast levels (100%, 25%, 10%, and 5%) under bright and dark backgrounds with multi-functional visual acuity tester (MFVA-100). The relationship of VA between bright and dark backgrounds was analyzed. Results: (1) Subjects with lower contrast level had significantly worse VA than those with higher contrast level when the background was identical (P<0.001); VA decreased gradually with the decrease of contrast level. At the same contrast level, the VA under dark background group was significantly worse than that under bright background group (P<0.001). (2) The VA at contrast level 100% under bright background was not linearly related to those under dark background (P>0.05), but was linearly related to those at other contrast levels under bright background (P<0.001). Under dark background, the VA at contrast level 100% was linearly related to those at other contrast levels(P<0.001). (3) The fluctuating differences (log unit) of VA increased with the decrease of contrast level, with the maximal difference found at contrast level 5% under dark background. Conclusion: The VA of healthy men under bright background is better than that under dark background. The VA decreases and individual variation increases gradually with the decrease of contrast level. There is no linear correlation of VA between the bright and dark backgrounds.

Objective: To investigate the expression of CD105 in oxygen-induced retinopathy (OIR) in C57BL/6J mice. Methods: Forty 7-day old C57BL/6J mice were evenly randomized into normal control group and hyperbaric oxygen group. The OIR model was induced with hyperbaric oxygen; the retinal neovascularization was observed by H-E staining and the expression of CD105 in OIR was observed by immunohistochernistry staining. Results: H-E staining indicated that the retinal neovascularization model was successfully estabished. CD105 was strongly expressed in the hyperbaric oxygen group, with the integral photodensity of angiogenesis being 9 985.63 ± 1 016.28 per mouse and the positive staining area being (14 246.61 ± 6 052.29) μm2 per mouse; CD105 was weakly expressed in the control group with the integral photodensity of angiogenesis being 1 625.36 ± 638.44 per mouse and the positive staining area being (3 619.31 ± 1 760.03) μm2 per mouse; the differences between the 2 groups were statistically significant (P < 0.01). Conclusion: CD105 may play a role in the retinal neovascularization; detection of CD105 might be valuable in evaluating retinal neovascularization and the subsequent treatment.

Objective: To establish a mouse model of human orbital rhabdomyosarcoma(RD). Methods: RD cells were cultured and implanted subcutaneously into the costal regions of nude mice and severe combined immunodeficiency (SCID) mice (4 weeks old). The nude mice were radiated by 60Co 1 day before the injection. The rhbdomyosarcoma tissue masses were harvested from nude mice and were subcutaneously implanted into the costal regions of another group of BALB/c mice (tumor tissue mass implantation). The tumor growth was observed in all groups and the growth curves were ploted. H-E staining was used to examine pathology of the tumor tissues. Results: Solid tumors were palpable 6-8 weeks after implantation in 60Co radiated nude mice and about 3-4 weeks after implantation in SCID mice. The solid tumors were obviously seen in the nude mice 2 weeks after tumor tissue mass transplantation. The tumor forming rates were 100% in all groups. The tumor growing curves were successfully ploted and the tumors had a progressive growth. Pathological findings of the tumor tissue were similar to those of human orbital rhabdomyosarcoma. Conclusion: The human orbital rhabdomyosarcoma models have been successfully established in nude mice and SCID mice. Tumor tissue mass implantation can shorten the tumor forming time in BALB/c nude mice. This research lays a foundation for further study or human orbital rhabdomyosarcoma.

Objective: To study the effect of cyclosporine A drug delivery system (CsA-DDS) on the prevention of posterior capsule opacification (PCO) after experimental intraocular lens implantation in rabbit eyes. Methods: Twenty healthy New Zealand white rabbits, whose left eyes and right eyes were used respectively as experiment eyes and controls, were subjected to extracapsular lens extraction and artificial lens implantation. During the operation, CsA-DDS with poly (lactideco-glycolide) as carriers or empty DDS was implanted in the capsular bag for the experimental eyes and controls respectively. After the operation, anterior chamber reaction, intraocular pressure (IOP) and CsA concentration were monitored and twelve weeks after the operation, the eyes were extracted for histopathological and morphological examinations. Results: There were no differences between the two groups in conjunctival congestion, IOP change and anterior chamber reaction. PCO was less severe in the experimental eyes than in the controls. Light microscopy revealed that posterior capsular membrane in the experimental eyes was slick, with no obvious proliferation, whereas in the controls, there were lens epithelial cell proliferation and cortex regeneration of different degrees. Morphological examination with electron microscope showed that in the experimental eyes, lens epithelial cells did not function actively and apoptosis occurred, whereas in the controls, epithelial cells presented active function. No marked ultrastructural changes were found in either group. Conclusion: Cs-DDS can inhibit PCO after intraocular lens implantation in rabbit eyes and does not have toxic effects on the surrounding ocular tissues. Therefore, it has a good potential for clinical use in prevention of PCO.

Objective: To study the effect of cyclosporine A drug delivery system (CsA-DDS) on the prevention of posterior capsule opacification (PCO) after experimental intraocular lens implantation in rabbit eyes. Methods: Twenty healthy New Zealand white rabbits, whose left eyes and right eyes were used respectively as experiment eyes and controls, were subjected to extracapsular lens extraction and artificial lens implantation. During the operation, CsA-DDS with poly (lactideco-glycolide) as carriers or empty DDS was implanted in the capsular bag for the experimental eyes and controls respectively. After the operation, anterior chamber reaction, intraocular pressure (IOP) and CsA concentration were monitored and twelve weeks after the operation, the eyes were extracted for histopathological and morphological examinations. Results: There were no differences between the two groups in conjunctival congestion, IOP change and anterior chamber reaction. PCO was less severe in the experimental eyes than in the controls. Light microscopy revealed that posterior capsular membrane in the experimental eyes was slick, with no obvious proliferation, whereas in the controls, there were lens epithelial cell proliferation and cortex regeneration of different degrees. Morphological examination with electron microscope showed that in the experimental eyes, lens epithelial cells did not function actively and apoptosis occurred, whereas in the controls, epithelial cells presented active function. No marked ultrastructural changes were found in either group. Conclusion: Cs-DDS can inhibit PCO after intraocular lens implantation in rabbit eyes and does not have toxic effects on the surrounding ocular tissues. Therefore, it has a good potential for clinical use in prevention of PCO.

AIM:To investigate the mechanism by which Shuangdan Mingmu Capsules alleviate retinal inflammatory responses in mice with diabetic retinopathy(DR)through the inhibition of the cGAS-STING signaling pathway.METHODS:SPF C57BL/6J male mice were first randomly divided into two groups: a DR model group(n=30)receiving daily intraperitoneal STZ injections(50 mg/kg)for 5 d, and a normal control group(n=10)receiving equivalent sodium citrate buffer. After successful diabetes induction, the mice were randomly divided into model group, Shuangdan Mingmu Capsules group, and positive drug group, with 10 mice in each group. The Shuangdan Mingmu Capsules group received gavage with Shuangdan Mingmu Capsules solution at a clinically equivalent dose(11.2 g/kg), while the positive drug group received gavage with Calcium Dobesilate solution at an equivalent dose of 11.6 mg/kg. The model group and the normal group received gavage with an equal volume of normal saline. Each group of mice received gavage once daily, and after 8 weeks of intervention treatment, Evans blue staining was used to detect the retinal leakage in each group of mice, HE staining was used to detect changes in the retinal tissue structure, TUNEL staining was used to observe the apoptosis of retinal cells, and immunofluorescence was used to detect the expression levels of retinal Rhodopsin, Opsin, Iba1 and GFAP. Furthermore, Western blot was used to detect the protein expression levels of cGAS, STING, TNF-α, IL-6 and IL-1β in the mouse retina.RESULTS:Compared with the normal group, the model group mice exhibited increased levels of neuroretinal leakage, retinal thinning, and elevated retinal cells apoptosis, accompanied by upregulation of Iba1 and GFAP expression levels in the retina, and downregulation of Rhodopsin and Opsin expression. The protein expression levels of cGAS, STING, TNF-α, IL-6, and IL-1β in the retinal tissue were significantly increased. In contrast to the model group, the Shuangdan Mingmu Capsules group and positive drug group mice showed decreased levels of neuroretinal leakage and retinal cells apoptosis, along with downregulation of Iba1 and GFAP expression levels in the retina, and upregulation of Rhodopsin and Opsin expression. The protein expression levels of cGAS, STING, TNF-α, IL-6, and IL-1β in the retinal tissue were significantly decreased. However, there was no significant difference between the Shuangdan Mingmu Capsules group and the positive drug group.CONCLUSION:Shuangdan Mingmu Capsules exert therapeutic effects on retinal inflammation and early damage in DR mouse models, with the underlying mechanism involving the inhibition of the cGAS-STING signaling pathway.

Objective: To evaluate the effect of subconjunctival injection of Bevacizumab (Avastin) on corneal neovascularization(CNV) in rabbits. Methods: Forty-eight New Zealand rabbits were randomly divided into three groups: normal control group (group A, 3 rabbits), neovascularization group (group B, 9 rabbits) and Bevacizumab treatment group (group C, 36 rabbits). Group C was further divided into group C1 (1 day small dose group), C2 (1 day high dose group), C3 (14 days small dose group) and C4 (14 days high dose group), with 9 rabbits each group. CNV model was made by suture in group B and C. Animals in group C were injected subconjunctivally with 0.1 ml or 0.2 ml Bevacizumab (25 mg/ml) in the left eyes. The growth of CNV was observed every day after operation and the neovascularization areas calculated. Expression of VEGF in the cornea was detected by immunohistochemistry on day 7, 14 and 28 after suture. VEGF content in the aqueous humor was determined by ELISA assay. Results: CNV growth in group C1 and C2 was inhibited significantly compared with that in group B on day 7, 14 and 28 (P<0.01). On day 28 the growth in group C3 and C4 was significantly inhibited compared with that in group B (P<0.01), that in group C1 was significantly inhibited than that in group C3, and that in group C2 was significantly inhibited compared with that in group C4 (P<0.01). VEGF levels in the cornea and aqueous humor in group B increased as time passed by, and they were positively associated with CNV area (P<0.01). On day 7, 14, and 28, the VEGF levels in the cornea and aqueous humor in C1 and C2 groups were significantly lower than that in group B (P<0.01). On day 28, those in group C3 and C4 were significantly lower than those in group B (P<0.01); those in group C1 were significantly lower than those in group C3 (P<0.01); and those in group C2 were significantly lower than those in group C4 (P<0.01). The CNV area and VEGF levels in the cornea and aqueou humor were similar between C1 and C2 groups and between C3 and C4 groups. Conclusion: Subconjunctival administration of Bevacizumab can effectively inhibit corneal neovascularization in experimental CNV model, and early administration has a better outcome than late administration. Bevacizumab may exert its effect by down-regulating VEGF in cornea and aqueous humor.

Objective: To observe the changes of visual evoked potential (VEP) in diabetic rats and the influence of nerve growth factor (NGF) and aminoguanidine (AG) on VEP. Methods: Diabetes was induced in adult male Wistar rats with streptozotocin (STZ). Rats were divided into normal control group (CON), diabetes model group (DM), NGF-treated group (D +N) and AG-treated group(D+A). VEP was measured during the 3rd month, 6th month, 9th month, and 12th month. Results: Compared with the CON group, all rest groups had longer latencies and lower amplitudes (P<0.01). During the 6th and 9th months, the latencies in group D+N and group D+A were significantly decreased (P<0.05) compared with DM group, and the amplitude was partially recoved during the 6th month. The changes during the 12th month were similar to those of the 9th month, except that the amplitude in D+A group was slightly higher than that in the DM group. Conclusion: NGF and AG can improve DM-induced elongation of VEP latency and decrease of VEP amplitude.