Evans blue staining to detect deep blood vessels in peripheral retina for observing retinal pathology in early-stage diabetic rats

AIM: To observe and compare the statistical significance of superficial and deep vascular leakage in the pathological changes of the diabetic rats retina after the Evans blue (EB) perfusion, and utilize the modified whole-retina spreading method to make the slides while protecting the periphery of the retina. METHODS: The Sprague-Dawley (SD) rats were randomly divided into 6 groups. Each group named as the normal groups for 4, 8, and 12wk and the diabetic groups for 4, 8, and 12wk. The EB was injected into the cardiovascular system of the rats at the different time points. The retina of each group was obtained for observation. RESULTS: The superficial vascular leakage was found in all 6 groups. The size of leakage area of superficial retinal blood vessels was (0.54±0.23)%, (0.65±0.11)%, and (0.58±0.10)% in normal group. No notable leakage was found in the deep blood vessels [(0.03±0.04)%, (0.03±0.05)%, and (0.03±0.05)%]. The deep retinal vascular leakage was found in the peripheral retina of diabetic rats. The size of leakage area of superficial retinal blood vessels in diabetic group were (0.53±0.22)%, (0.69±0.16)%, and (0.52±0.11)%. The leakage areas of deep blood vessels were (0.54±0.50)%, (1.42±0.16)%, and (1.80±0.07)% at 4, 8, and 12wk, respectively. There was a statistically difference of the leakage area between the 8th week and the 4th week of diabetes group (P=0.003). The statistically significant difference between the diabetes and the control groups was noted at 4wk and 8wk (P<0.001). CONCLUSION: The main retinal pathological changes of early-stage diabetic rats are the vascular leakage of the periphery of deep retina. Diabetic rats modeled after 8wk have semi-quantitative statistical difference compared with the normal rats, thus early intervention treatment research can start at this time point.

Quantification of noncircular stent expansion after TAVR into a pathological annulus and its impact on paravalvular leakage

Patients undergoing transcatheter aortic valve replacement (TAVR) may suffer severe clinical complications, caused by paravalvular leakage (PVL) which is defined as leakage between TAVR and aortic annulus. PVL is often facilitated by a severely calcified annulus. This limits the expansion of a self-expandable TAVR stent. To assess TAVR performance in terms of leakage, measurement of regurgitation fraction in a pathophysiological annulus is recommended according to ISO 5840. For this purpose, a configuration of a circular annulus with a calcification nodule has been proposed in the recently published ISO 5840. The impact of the proposed pathophysiological annulus model on the expansion of self-expandable TAVR stents and on the regurgitation fraction was investigated in this study. For this purpose, two commercially available selfexpandable TAVRs (Evolut R and Portico) were implanted in a calcified annulus model. Circular expansion of the TAVR stents was investigated based on μCT scans of the implanted TAVR. The calcification-induced area in which retrograde flow can occur during diastole was detected. These results were then compared with the experimentally determined regurgitation fraction obtained from pulse duplicator tests. The results of the μCT scans showed a continuous leakage area in the region of the annulus for the Evolut R compared to a locally larger leakage area of the Portico, which, however, reattaches to the annulus in the distal inflow region. The hydrodynamic measurements confirmed a smaller leakage in the pathological annulus for the Portico. In summary, it can be assumed that a continuous leakage area in the TAVR stent inflow region encourages the PVL of TAVR.

Evaluation of Outdoor Particle Infiltration into Classrooms Considering Air Leakage and Other Building Characteristics in Korean Schools

We analyzed the effects of air leakage and other building characteristics on outdoor particle penetration in classrooms. The building characteristics including air leakage of 12 Korean schools were investigated, and onsite measurements were conducted to estimate the outdoor particle infiltration. The correlations among variables associated with air leakage and building characteristics and outdoor particle infiltration were analyzed using the Pearson correlation analysis and linear regression. The effective leakage area (ELA) of classrooms varied highly from 340.8–1566.9 cm2, and a significant disparity in the air leakage characteristics among the classrooms appeared. The results of onsite measurement revealed that the average ELA was larger in the corridor side with an ELAcorridor-side of 264.7 cm2 than in the outdoor side (ELAoutdoor-side of 93.1 cm2). Results of correlation analysis indicated a high correlation (r = 0.68~0.78, p-value < 0.05) between the size resolved outdoor particle source (P × λ) and specific ELA. Particularly, a strong linear relation (R2 = 0.69~0.71) with specific ELAcorridor-side was seen. Results suggest that cracks between windows and doors in the corridor side considerably affect outdoor particle penetration. These results indicate the importance of improving the airtightness of not only the building envelope but also the inter-zonal walls for effectively reducing the outdoor particle infiltration into classrooms.

Application of iris fluorescein angiography in diabetic iridopathy and retinopathy in brown iris

Purpose: This study aimed to evaluate the relationship between diabetic iridopathy (DI) and diabetic retinopathy (DR) and distinguish iris neovascular and physiological leakage using iris fluorescein angiography (IFA). Methods: A total of 210 subjects were prospectively recruited in this study. Sixty normal subjects were divided equally into three groups (<40 years old, 40–59 years old, and 60–79 years old). One hundred fifty patients with diabetic mellitus (DM) were divided equally into five groups (no retinopathy, mild non proliferative DR (mildnPDR), moderate nPDR, severe nPDR, and PDR group). Normal subjects underwent IFA. Patients with DR underwent both IFA and ultrawide field fundus fluorescein angiography (uwFFA) at the same time. The leakage time and area were recorded and compared with each group. Results: Fluorescein leakage occurred at the pupillary edge of patients that were 40–59 and 60–79 years old but not in those <40 years old. In the PDR group, the leakage time was earlier and the leakage area was larger than nPDR and patients with no retinopathy ( p = 0.039 and p = 0.005, respectively). However, the leakage time and area were not significantly different between patients with no retinopathy and nPDR ( p > 0.05). Conclusion: IFA examination can only assist in estimating the fundus severity of PDR patients, whereas the fundus changes of patients with no retinopathy and nPDR were not related to DI changes. Trial registration No.: ChiCTR1800018003. The date of registration: Aug 26th, 2018.

Diabetic Macular Edema Treatment with Bevacizumab Does Not Depend on the Retinal Nonperfusion Presence

This study evaluated the relationship between the retinal nonperfusion area (NPA) presence and the effectiveness of bevacizumab treatment (IVB) in patients with diabetic macular edema (DME). It also tested the prognostic usefulness of ultra-wide-field fluorescein angiography (UWFFA) and OptosAdvance software for diabetic retinopathy monitoring. Eighty-nine patients with DME with a macular central subfield thickness CST ≥ 250 μ m , with ( N = 49 eyes) and without ( N = 49 eyes) retinal NPA, underwent nine bevacizumab injections over 12 months. NPA distribution, leakage area distribution, microaneurysm (MA) count, macular CST, diabetic retinopathy severity, and best-corrected visual acuity (BCVA) were assessed. The results show that bevacizumab reduced the macular CST from 420 to 280 μm ( p < 0.001 ) and improved BCVA ( p < 0.001 ) by about 10 ETDRS letters in both groups of patients. Additionally, the therapy reduced total retinal NPA from 29 (14-36) mm2 to 12 (4-18) mm2 (Me (Q1-Q3); p < 0.001 ) in patients with diagnosed nonperfusion. The effect of the therapy measured with vascular leakage, MA count, BCVArelative, and CSTrelative strongly depended on the zone of the retina and the NPA distribution. We conclude that the bevacizumab treatment had a positive effect on DME and BCVA in both study groups and on the size of retinal NPA in patients with retinal nonperfusion.

Effect of hydraulic and geometric factors upon leakage flow rate in pressurized pipes

ABSTRACT Computational Fluid Dynamics (CFD) simulations of a leakage in a pressurized pipe were undertaken to determine the empirical effects of hydraulic and geometric factors on the leakage flow rate. The results showed that pressure, leakage area and leakage form, influenced the leakage flow rate significantly, while pipe thickness and mean velocity did not influence the leakage flow rate. With relation to the interactions, the effect of pressure upon leakage flow rate depends on leakage area, being stronger for great leakage areas; the effects of leakage area and pressure on leakage flow rate is more pronounced for longitudinal leakages than for circular leakages. Finally, our results suggest that the equations that predict leakage flow rate in pressurized pipes may need a revision.

High rise buildings stairwells pressure differential systems tests and improvement solutions

The task of fire pressure differential systems in a building is to prevent smoke from entering protected spaces such as stairwells and areas that should remain smoke-free in the event of fire. The required overpressure must consider leakage within the protected space. This article presents the results of testing to determine the impact of leakage of the protected space on the conditions for maintaining overpressure. The research was conducted in accordance with draft standard N161-prEN12101-6. The pressure distribution as a function of time was obtained for stairwells with different levels of leakage, using a constant flow aeration fan as well as systems with a variable airflow. Practical application: Designers of differential pressure smoke control systems are required to calculate aeration fan airflow volume. The leakage level of protected spaces should be taken into consideration given that European Standard EN12101-6 suggests that gap areas should be minimal. Consequently, modern building design and construction requires estimation of the leakage area in such protected spaces. The objective is to improve safety of buildings and reduce the system reaction time during a fire.