A Fair Assessment of Evaluation Tools for the Murine Microbead Occlusion Model of Glaucoma

Despite being one of the most studied eye diseases, clinical translation of glaucoma research is hampered, at least in part, by the lack of validated preclinical models and readouts. The most popular experimental glaucoma model is the murine microbead occlusion model, yet the observed mild phenotype, mixed success rate, and weak reproducibility urge for an expansion of available readout tools. For this purpose, we evaluated various measures that reflect early onset glaucomatous changes in the murine microbead occlusion model. Anterior chamber depth measurements and scotopic threshold response recordings were identified as an outstanding set of tools to assess the model’s success rate and to chart glaucomatous damage (or neuroprotection in future studies), respectively. Both are easy-to-measure, in vivo tools with a fast acquisition time and high translatability to the clinic and can be used, whenever judged beneficial, in combination with the more conventional measures in present-day glaucoma research (i.e., intraocular pressure measurements and post-mortem histological analyses). Furthermore, we highlighted the use of dendritic arbor analysis as an alternative histological readout for retinal ganglion cell density counts.

Study on the occlusion of the visibility window on highway exit ramps

Traffic accidents frequently occur at the nose of highway exit ramps for a variety of reasons. When attempting to take an exit, a driver’s line of sight may be obscured by the curvature or slope of the main expressway, roadside vegetation, traffic signs, and other vehicles traveling alongside. These increase the likelihood of accidents due to inaccurate or poor driver judgement when approaching a highway exit. Because of emotional responses that accompany the possibility of missing an exit, many drivers act irrationally through haphazard acceleration or braking, aggressive lane changes; in some cases, even coming to a complete stop and reversing against the flow of high speed traffic to correct their course. This study applies to curved highway exit corridors with a poor line of sight. The total visible area of the exit ramp is defined in accordance with the design specifications of both the highway routes and exit ramps, which was then further refined by considering the driving characteristics of both the drivers and of surrounding traffic. This study set out to establish a reliable occlusion model of highway exits with the following goals in mind. Geometric equations describing the area and volume of the target area of the exit ramp are established. Discrete expression equation was deployed to establish the occlusion model for the target area within the visual field. Parameters taken from specifications of the Hunan section of the Shanghai-Kunming Expressway are used for multiple calculations, in which obstruction patterns of objects with the same width, and objects with different width at different positions are analyzed. Based on the patterns observed from stimulated experiments mentioned above, multiple effective measures were proposed to prevent the obstruction of the highway exit ramp. In summary, this study provides theoretical support for prevention of obstruction as well as an anti-occlusion model for better identification of the highway exit ramps by intelligent vehicle systems.

A novel rabbit thromboembolic occlusion model

BackgroundTo develop a preclinical thromboembolic occlusion model for studying revascularization strategies.MethodsClot analog with barium sulfate was injected into the distal aorta in 9 New Zealand white rabbits. The situation of aorta occlusion was compared among fibrin-rich (n=4), red blood cell (RBC)-rich (n=3), and whole blood clot analogs (n=2) using digital subtraction angiography. Arterial geometries, histologic features and circumferential stretch of the distal aorta in rabbits were compared with the common carotid artery in swine and the distal internal carotid artery (ICA) in humans. Aspiration thrombectomy and mechanical thrombectomy using a stent retriever were performed in two rabbits.ResultsThe aortic bifurcation was occluded after a single delivery of clot in 4 cases. It was occluded after the second clot injection in the 5 remaining rabbits. Fragmentation of RBC-rich clots occurred during clot injection in 2 cases. The mean diameters of the distal aorta and right common iliac artery in rabbits were 3.7±0.4 and 2.8±0.3 mm, respectively; the mean diameters of human ICA, and first and second segments of the middle cerebral artery (M1, M2) were 3.6±0.4, 3.1±0.4, and 2.4±0.4 mm, respectively. Arterial revascularization was achieved in both rabbits. Geometric, mechanical and histological factors of the distal aorta in rabbit were more close to human distal ICA than swine carotid artery.ConclusionArterial occlusion can be achieved at the aortic bifurcation in rabbits, which is comparable to human ICA bifurcation. This thrombectomy model has the potential to be used for testing of thrombectomy devices.