Effects of photoperiod and food on glucose intolerance and subsequent ocular pathology in the fat sand rat.

Type 2 diabetes mellitus (T2DM) and its ocular complications, such as cataract and diabetic retinopathy (DR) have been linked to circadian rhythm-disturbances. Using a unique diurnal animal model, the sand rat (Psammomys obesus) we examined the effect of circadian disruption by short photoperiod acclimation on the development of T2DM and related ocular pathologies. We experimented with 48 male sand rats. Variables were day length (short photoperiod, SP, vs. neutral photoperiod NP) and diet (standard rodent diet vs. low-energy diet). Blood glucose, the presence of cataract and retinal pathology were monitored. Histological slides were examined for lens opacity, retinal cell count and thickness. Animals under SP and fed standard rodent diet (SPSR) for 20 weeks had higher baseline blood glucose levels and lower glucose tolerance compared with animals kept under NP regardless of diet, and under SP with low energy diet (SPLE). Animals under SPSR had less cells in the outer nuclear layer, a lower total number of cells in the retina, and a thickened retina. Higher blood glucose levels correlated with lower number of cells in all cellular layers of the retina and thicker retina. Animals under SPSR had higher occurrence of cataract, and a higher degree of cataract, which correlated with higher blood glucose levels. Sand rats kept under SPSR develop cataract and retinal abnormalities indicative of DR, whereas sand rats kept under NP regardless of diet, or under SPLE, do not. These ocular abnormalities significantly correlate with hyperglycemia.

The distribution of relaxin receptors in the anterior segment of primary open-angle glaucoma patients.

Purpose: Relaxin is a polypeptide hormone produced by the corpus luteum and the decidua in females and by the prostate in males. It has vasodilatory and antifibrotic effects. In the past, it has been reported that injection of relaxin hormone has caused a reduction in the intraocular pressure although its mechanism has not yet been fully understood and the expression of relaxin receptors has not yet been evident in the human eye. Therefore, the purpose of this current study was to examine the presence of relaxin receptors in the human eye anterior segment. Methods: This is an interventional non-randomized study. Patients with primary open-angle glaucoma who underwent trabeculectomy were recruited. During the surgery, a punch biopsy (including the cornea, sclera, trabecular meshwork, and Schlemm's canal) was taken and stained with hematoxylin-eosin, and immunohistochemistry staining for relaxin/insulin-like family peptide receptor 1 (RXFP1). Results: A positive staining was noted for RXFP1 in the inner uveal, corneoscleral, and cribriform meshwork and Schlemm's canal's endothelium. Negative staining for RXFP1 was noted in the cornea and sclera. Conclusion: RXFP1 is present in the anterior segment drainage system of the human eye. Therefore, this receptor may have an active role in regulating the outflow facility and in the reduction of intraocular pressure.

Mild carotid stenosis creates gradual, progressive, lifelong brain, and eye damage: An experimental laboratory rat model.

In humans, carotid stenosis of 70% and above might be the cause of clinical symptoms such as transient ischemic attack and stroke. No clinical or animal studies have evaluated mild carotid occlusion, and few examined unilateral occlusion. Here, Westar rats underwent bilateral or unilateral carotid occlusion of 28-45%. Long-term effects were evaluated 9-11 months later. We conducted cognitive evaluation using spatial learning in a water maze and exploration behavior in an open field. Morphology of the brain was examined by MRI using diffusion-tensor imaging (DTI) and immunohistochemistry staining of the brain and eyes. Cognitive deficit was found in spatial memory and exploration behavior in both occluded groups. Brain and eyes histology presented severe damage in the bilateral group, compared to the unilateral one. DTI revealed an increase in mean diffusivity (MD) in the ventral thalamus and a decrease in fractional anisotropy in optic nerve and optic tract in bilateral rats, while unilateral rats showed only an increase in MD in the ventral pons. In those areas, a significant change in astrocytes, microglia, and number of apoptotic cells were found. Bilateral occlusion produced severe damage to both retinas, while unilateral occlusion produced damage mainly in the occluded side. We found that mild carotid stenosis, even in a unilateral occlusion, creates behavioral abnormalities presented by brain and eye histopathology. The results support our hypothesis that gradual formation of mild carotid stenosis along the life course leads to progressive damage that may create different degenerative diseases at a later age.

Correction: Procollagen C-Proteinase Enhancer 1 (PCPE-1) as a Plasma Marker of Muscle and Liver Fibrosis in Mice.

[This corrects the article DOI: 10.1371/journal.pone.0159606.].

Procollagen C-Proteinase Enhancer 1 (PCPE-1) as a Plasma Marker of Muscle and Liver Fibrosis in Mice.

Current non-invasive diagnostic methods of fibrosis are limited in their ability to identify early and intermediate stages of fibrosis and assess the efficacy of therapy. New biomarkers of fibrosis are therefore constantly sought for, leading us to evaluate procollagen C-proteinase enhancer 1 (PCPE-1), a fibrosis-related extracellular matrix glycoprotein, as a plasma marker of fibrosis. A sandwich ELISA that permitted accurate measurements of PCPE-1 concentrations in mouse plasma was established. Tissue fibrosis was assessed using histochemical, immunofluorescence, and immunoblotting analyses for type I collagen and PCPE-1. The normal plasma concentration of PCPE-1 in 6 weeks to 4 months old mice was ~200 ng/ml (189.5 ± 11.3 to 206.8 ± 13.8 ng/ml). PCPE-1 plasma concentrations in four and 8.5 months old mdx mice displaying fibrotic diaphragms increased 27 and 40% respectively relatively to age-matched control mice, an increase comparable to that of the N-propeptide of procollagen type III (PIIINP), a known blood marker of fibrosis. PCPE-1 plasma levels in mice with CCl4-induced liver fibrosis increased 34 to 50% relatively to respective controls and reflected the severity of the disease, namely increased gradually during the progression of fibrosis and went down to basal levels during recovery, in parallel to changes in the liver content of collagen I and PCPE-1. The results favor PCPE-1 as a potential new clinically valuable fibrosis biomarker.

Healing rate of corneal erosions: comparison of the effect of chloramphenicol eye drops and ointment and high-concentration hyaluronic acid in an animal model.

PURPOSE: The aim of this study was to compare the effect of chloramphenicol eye drops or ointment, high-concentration hyaluronic acid, or no treatment on reepithelialization of corneal erosions in an experimental model. METHODS: Uniform 6-mm corneal erosions were created in 23 rabbit eyes. The rabbits were randomized to 4 treatment groups: (1) chloramphenicol eye drops group, (2) chloramphenicol ointment, (3) hyaluronic acid 2.3%, and (4) untreated. Treatment was administered every 8 hours until reepithelialization occurred. Eyes were photographed every 8 hours with a cobalt blue-filtered light with fluorescein drops until reepithelialization occurred. The area of the erosion at each time point was analyzed. RESULTS: There were no significant differences in the reepithelialization of the corneal erosion among the 3 treatment groups (72-75 hours, P > 0.05). The time was significantly shorter (51 hours) for the control untreated group (P = 0.005). CONCLUSIONS: The use of chloramphenicol in the form of eye drops or ointment for prophylaxis in corneal erosions has a similar effect on the healing rate of the erosion. Both forms of the antibiotic and high-concentration hyaluronic acid had an effect of slowing down the healing of the erosion when compared with when no treatment was given. Therefore, the decision to treat erosions with eye drops or ointment can be based on the patient's comfort.

Topical tacrolimus for the management of acute allergic conjunctivitis in a mouse model.

BACKGROUND: Acute allergic conjunctivitis is a constantly challenging condition that often requires steroids for effective management. Alternative treatment options are needed due to the potential side effects of steroids. Tacrolimus has been used for vernal/atopic conjunctivitis. The aim of our study was to investigate the therapeutic effect of topical administration of 0.03 % tacrolimus (eye drops or ointment) in comparison to 0.1 % dexamethasone in a mouse model of acute allergic conjunctivitis. METHODS: BALB/c mice were sensitized by an intraperitoneal injection of 10 µg/0.2 ml ovalbumin (OVA) absorbed on ALUM (2.0 mg) on days 1 and 8. They were challenged by topical instillation of 2 µl of 15 % OVA (absorbed in 10 % glycerol) twice daily, on days 15-21. Treatment was administered twice daily on days 17-21. Mice were randomly assigned topical treatment groups: Group 1, 0.1 % dexamethasone drops; Group 2, 0.03 % tacrolimus drops; Group 3, 0.03 % tacrolimus ointment; Group 4 PBS drops (control). On day 22 all mice underwent clinical evaluation, blood sampling for IgE levels, and conjunctivas were removed for eosinophil counting. RESULTS: IgE and OVA-specific IgE levels were similar among all groups, demonstrating induction of allergic reaction in all mice. Significantly lower clinical scores were found among all treated groups as compared to controls (P < 0.001), while no significant difference was found among the three treatment groups (P > 0.05). Conjunctival eosinophil counts were significantly lower in Group 1 (P < 0.05) as compared to the other groups. CONCLUSIONS: The clinical efficacy of topical 0.03 % tacrolimus was similar to 0.1 % dexamethasone for acute allergic conjunctivitis.

Effect of amniotic membrane transplantation on the healing of bacterial keratitis.

PURPOSE: To study, with the use of an animal model, the efficacy of amniotic membrane (AM) transplantation as adjunctive treatment in corneal healing after bacterial keratitis. METHODS: Staphylococcus aureus keratitis was induced in 47 rats by injection of bacteria into the corneal stroma. Treatment was started 48 hours later with one of three randomly assigned protocols: cefazolin drops (50 mg/mL) and AM transplantation (n = 16); nonpreserved 0.9% saline drops and AM transplantation (n = 15); or cefazolin without AM transplantation (n = 16). Cefazolin and saline drops were administered every 30 minutes for 6 hours, then hourly for 6 hours. AM was transplanted 24 hours after termination of cefazolin or saline treatment. Results were clinically assessed 7 days after AM transplantation or at the corresponding time in the nontransplanted animals. The rats were then killed, and their corneas were removed for bacterial counts or histopathologic examination. RESULTS: The best clinical results were observed in the group treated with cefazolin and AM transplantation, manifested by the least corneal haze and neovascularization (P = 0.007 and P = 0.014, respectively) and minimal bacterial counts (28 colony-forming units [CFU]/mL compared with 160 CFU/mL and 240 CFU/mL, respectively). Histopathologic examination showed that the central corneal vessels from rats treated with cefazolin and AM were smaller and less congested than those from the other two groups. CONCLUSIONS: AM transplantation is a useful adjunctive treatment after bacterial keratitis in this rat model. The transplanted AM improved the healing process, resulting in decreased corneal haze and less neovascularization.

Drug modification of angiogenesis in a rat cornea model.

PURPOSE: To evaluate the influence of some widely used antiglaucoma agents on angiogenesis in a novel rat cornea model. METHODS: Angiogenesis was induced in 32 rats by slow-release polymer pellets containing basic fibroblast growth factor (bFGF) placed in a corneal micropocket. Angiogenesis was later measured and compared in groups of rats given one of four antiglaucoma drug therapies and one control group. The drugs were commercially available preparations of prostaglandins, beta-blockers, alpha-2 agonists, and carbonic anhydrase inhibitors given for 7 days in a manner similar to that used in humans. Growth was measured by calculating the maximum linear vessel growth divided by pellet-limbus distance. RESULTS: Biomicroscopic observation disclosed that all tested animals showed an induction of neovascular reactions in their corneal stroma. The growth index results for the control, latanoprost, dorzolamide, brimonidine, and timolol malate groups were 1.65 +/- 0.16, 1.98 +/- 0.18, 1.85 +/- 0.19, 2.03 +/- 0.38, and 1.65 +/- 0.14, respectively, confirming the hypothesis that topically delivered antiglaucoma drugs modify the normal angiogenic response. Of them, the prostaglandins showed the most prominent angiogenic stimulatory effect (P = 0.03). CONCLUSIONS: This modified micropocket assay of corneal angiogenesis in rats demonstrated the stimulatory effect of several widely used topically delivered antiglaucoma medications on the angiogenic process. The results indicate that the selection of drugs for treating different ophthalmic diseases should take into account their influence on angiogenic processes.

Effect of fourth-generation fluoroquinolones on the healing rate of corneal erosions in an animal model.

PURPOSE: To compare the rate of epithelial healing of corneal erosion in an animal model with 2 commercial formulations of fourth-generation fluoroquinolones: 0.3% gatifloxacin and 0.5% moxifloxacin. METHODS: Corneal erosions, 6 mm in diameter, were created in 28 rabbit eyes. The rabbits were randomized to receive topical gatifloxacin, moxifloxacin, or nonpreserved saline. Drops were administered every 15 minutes for 1 hour, then hourly for 3 hours, and then 4 times daily until the erosion reepithelialized. Eyes were examined with fluorescein drops and photographed every 12 hours with a cobalt blue-filtered light. When reepithelialization was observed, the rabbits were euthanized, and their eyes were enucleated for histopathologic evaluation. RESULTS: Reepithelialization of the corneal erosions was fastest in the saline-treated eyes (57.3 +/- 8 hours), followed by moxifloxacin (62.7 +/- 11.7 hours) and gatifloxacin (66 +/- 8.5 hours). These differences in the time to closure of the erosions among the 3 groups were not statistically significant. Although significant differences were found among the healing progression curves when all 3 groups were compared (P = 0.042), the difference between the 2 antibiotic-treated groups was not significant. CONCLUSIONS: Only slight differences in epithelial healing rates were found between the gatifloxacin-, moxifloxacin-, and saline-treated groups, suggesting that the 2 fluoroquinolones may have an equivalent role as prophylactic treatment of trauma- or surgery-induced corneal erosions.

Association study of CAG repeats in the KCNN3 gene in Israeli patients with major psychosis.

OBJECTIVES: Several studies reported contradictory findings regarding the association of major psychosis with CAG repeats in the KCNN3 gene. We investigated the contribution of the CAG repeat at the KCNN3 gene, localized to chromosome 1q21.3, to the genetic susceptibility for schizophrenia, schizoaffective and bipolar disorders. METHODS: Analysis of the number of CAG repeats and the differences in allele length were performed for Israeli Ashkenazi Jews, non-Ashkenazi Jews, and Arabs diagnosed with major psychosis (n=181) versus matched ethnic controls (n=207). RESULTS: We found no significant difference in the number of CAG repeats between the entire sample of patients and controls. However, an analysis of the differences of allele length revealed a significantly greater number of patients with identical allele length (43.1%) when compared with normal controls (30.4%). Furthermore, an earlier age of non-paranoid schizophrenia onset was found associated with differences in allele sizes. There were no significant differences in the number of CAG repeats and the differences in allele length when subjects were grouped according to gender, ethnic origins of their parents, family history, and diagnostic groups. CONCLUSIONS: Our results support the hypothesis that a contribution of the KCNN3 gene to genetic susceptibility to major psychosis and their phenotypic polymorphism may be related to the difference of allele length rather than to the number of CAG repeats.

An association of CAG repeats at the KCNN3 locus with symptom dimensions of schizophrenia.

BACKGROUND: In 1999 Cardno et al reported that long CAG repeats in the calcium-activated potassium channel gene hSKCa3/KCNN3 are associated with higher negative symptom dimension scores in schizophrenia patients. There has been no attempt to replicate the results. In this study, we investigated whether a symptom polymorphism of schizophrenia is associated with both the CAG repeat numbers and the difference in allele sizes. METHODS: We tested the association of CAG repeats with symptom models of schizophrenia in 117 unrelated Jewish patients. A multivariate analysis (MANOVA) of two models of schizophrenia with the repeat distribution and the difference in allele sizes was performed. RESULTS: We found a significant positive association of the number of CAG repeats with negative syndrome, anergia, activation, and paranoid symptoms. In addition, nonparanoid schizophrenia patients who had differences in allele sizes were characterized by earlier onset of illness. CONCLUSIONS: The study supports the hypothesis that the combined effect of long CAG repeats and the differences in allele sizes contribute to symptom expression of schizophrenia, particularly on the anergia-activation-paranoid axis.