Differences in collateral vessel formation after experimental retinal vein occlusion in spontaneously hypertensive rats and wild-type rats.

Objective: Retinal vein occlusion (RVO) can lead to visual impairment, but the development of collateral vessels can sometimes mitigate significant damage. This study aimed to investigate the relationship between collateral vessels and hypertension, the most common underlying condition associated with RVO, by comparing spontaneously hypertensive rats (SHRs) and wild-type Wister rats (WWRs). We also examined the differences between WWRs and SHRs in terms of sphingosine 1-phosphate receptor 1 (S1PR1) expression and its product nitric oxide synthase 3 (NOS3) expression, which are involved in the formation of collateral vessels after vascular occlusion. Methods: Laser photocoagulation (PC) was used to occlude one randomly selected retinal vein in WWRs and SHRs, and the area surrounding the occluded vessel was examined using optical coherence tomography angiography. If reperfusion of the occluded vessel occurred within 2 weeks, the vessel was re-occluded repeatedly by PC. The number of eyes with successfully occluded vessels accompanied by collateral vessels was recorded. Then, WWRs and SHRs were divided into the following four groups: 1) control (no treatment), 2) vehicle (20% DMSO), 3) S1PR1 agonist (2 mg/mL SEW2871), and 4) S1PR1 antagonist (0.25 mg/mL VPC 23019) groups. The drugs were administered intravitreally in all groups except the control. The number of laser shots required for successful RVO was recorded. Histological evaluation and quantitative real-time PCR of S1PR1 and NOS3 were performed to elucidate the mechanisms underlying collateral vessel formation. Results: The proportion of eyes achieving successful vein occlusion was lower in SHRs (4/12 eyes, 33.3%) than in WWRs (8/10 eyes, 80%, p = 0.043). NOS3 expression at 6 h after PC was significantly higher in WWRs than in SHRs (p = 0.021). In WWRs treated with SEW2871, vein occlusion failed in 7 of 10 eyes (70%). The expression of NOS3 was significantly higher in the SEW2871 treatment group than in the untreated group (p < 0.001). Furthermore, NOS3 expression was significantly higher after SEW2871 treatment in WWRs than in SHRs (p = 0.011). Conclusion: In hypertensive environments, collateral vessels are less likely to develop, and S1PR1 may be involved in this phenomenon.

16S rRNA nanopore sequencing for the diagnosis of ocular infection: a feasibility study.

OBJECTIVE: We conducted a feasibility study to verify the effectiveness of 16S ribosomal RNA (rRNA) gene analysis using the nanopore sequencer MinION for identifying causative bacteria in several types of ocular infections. METHODS AND ANALYSIS: Four cases of corneal ulcers, one case of endophthalmitis and one case of a conjunctival abscess were included in this study. DNA was extracted from corneal scraping, vitreous samples and secretions from the conjunctival abscess. We conducted 16S rRNA gene amplicon sequencing using MinION and metagenomic DNA analysis. The efficacy of bacterial identification was verified by comparing the conventional culture method with smear observations. RESULTS: 16S rRNA gene sequencing analysis with MinION identified the causative organisms promptly with high accuracy in approximately 4 hours, from ophthalmic specimens. The results of the conventional culture method and 16S rRNA gene sequencing were consistent in all cases. In four of the six cases, a greater variety of organisms was found in the 16S rRNA gene analysis than in bacterial culture. CONCLUSION: Using our workflow, 16S rRNA gene analysis using MinION enabled rapid and accurate identification possible in various kinds of bacterial ocular infections.

Successful identification of Granulicatella adiacens in postoperative acute infectious endophthalmitis using a bacterial 16S ribosomal RNA gene-sequencing platform with MinION™: A case report.

Purpose: To evaluate the efficacy of identifying the bacteria by aqueous sampling and vitreous sampling in postoperative infectious endophthalmitis using 16S ribosomal RNA (rRNA) gene analysis with a nanopore sequencer (MinION™). Observation: A 55-year-old woman who underwent cataract surgery at an ophthalmology clinic 18 days ago was referred to our hospital for suspected endophthalmitis. She had light perception visual acuity in her right eye; however, the eye was severely inflamed, with a hypopyon and a fibrinous membrane in the anterior chamber. The fundus was not visible because of vitreous opacity on a B-scan image. Based on the diagnosis of postoperative acute infectious endophthalmitis, we performed a vitrectomy, intraocular lens extraction, and silicone oil tamponade. On postoperative day 14, the inflammation resolved. An aqueous sample was collected before surgical treatment, and the vitreous sample was collected during the operation. Both samples underwent 16S rRNA gene analysis with a nanopore sequencer MinION™ to identify the causative organism. Conclusions and Importance: In the aqueous humor, Granulicatella adiacens and Cutibacterium acnes were identified before the operation, while only Granulicatella adiacens was detected in the vitreous sample after the operation. Although the aqueous humor sample might contain commensal bacteria, it could provide a predictable result before the operation. It can also provide a substitute for a vitreous sample to allow earlier identification of the causative organism.