Sialic acids regulate microvessel permeability, revealed by novel in vivo studies of endothelial glycocalyx structure and function

The endothelial glycocalyx forms a continuous coat over the luminal surface of all vessels, and regulates multiple vascular functions. The contribution of individual components of the endothelial glycocalyx to one critical vascular function, microvascular permeability, remains unclear. We developed novel, real time, paired methodologies to study the contribution of sialic acids within the endothelial glycocalyx to the structural and functional permeability properties of the same microvessel in vivo. Single perfused rat mesenteric microvessels were perfused with fluorescent endothelial cell membrane and glycocalyx labels, and imaged with confocal microscopy. A broad range of glycocalyx depth measurements (0.17–3.02μm) were obtained with different labels, imaging techniques and analysis methods. The distance between peak cell membrane and peak glycocalyx label provided the most reliable measure of endothelial glycocalyx anatomy, correlating with paired, numerically smaller values of endothelial glycocalyx depth (0.078±0.016μm) from electron micrographs of the same portion of the same vessel. Disruption of sialic acid residues within the endothelial glycocalyx using neuraminidase perfusion decreased endothelial glycocalyx depth and increased apparent solute permeability to albumin in the same vessels in a timedependent manner, with changes in all three true vessel wall permeability coefficients (hydraulic conductivity, reflection coefficient, and diffusive solute permeability). These novel technologies expand the range of techniques that permit direct studies of the structure of the endothelial glycocalyx and dependent microvascular functions in vivo, and demonstrate that sialic acid residues within the endothelial glycocalyx are critical regulators of microvascular permeability to both water and albumin

Effect of bilayer charge on lipoprotein lipid exchange

Lipoproteins play a key role in the onset and development of atherosclerosis, the formation of lipid plaques at blood vessel walls. The plaque formation, as well as subsequent calcification, involves not only endothelial cells but also connective tissue, and is closely related to a wide range of cardiovascular syndromes, that together constitute the number one cause of death in the Western World. High (HDL) and low (LDL) density lipoproteins are of particular interest in relation to atherosclerosis, due to their protective and harmful effects, respectively. In an effort to elucidate the molecular mechanisms underlying this, and to identify factors determining lipid deposition and exchange at lipid membranes, we here employ neutron reflection (NR) and quartz crystal microbalance with dissipation (QCM-D) to study the effect of membrane charge on lipoprotein deposition and lipid exchange. Dimyristoylphosphatidylcholine (DMPC) bilayers containing varying amounts of negatively charged dimyristoylphosphatidylserine (DMPS) were used to vary membrane charge. It was found that the amount of hydrogenous material deposited from either HDL or LDL to the bilayer depends only weakly on membrane charge density. In contrast, increasing membrane charge resulted in an increase in the amount of lipids removed from the supported lipid bilayer, an effect particularly pronounced for LDL. The latter effects are in line with previously reported observations on atherosclerotic plaque prone regions of long-term hyperlipidaemia and type 2 diabetic patients, and may also provide some molecular clues into the relation between oxidative stress and atherosclerosis

Riedel’s Procedure: A Modification to Obliterate Step Defect

Sinus surgery was first introduced by the ancient Egyptians. In 1750 was the first modern description of frontal sinus surgery. In 1898, Riedel advocated complete removal of the anterior table and floor of the frontal sinus while simultaneously stripping the mucosa. The major postoperative issue involved gross forehead deformity. We aim to provide a modification to reduce the postoperative “step” defect. Riedel’s procedure is an effective way of managing frontal sinus disease when endoscopic surgery has repetitively failed. Use of a pedicled pericranial/galeal soft tissue flap can effectively reduce cosmetic deformity postoperatively

Three-dimensional endoscopy: The future of nasoendoscopic training.

OBJECTIVES/HYPOTHESIS Three-dimensional (3D) endoscopy is an emerging tool in surgery that provides real-time depth perception. Its benefits have been investigated in surgical training, but the current literature lacks significant objective outcome data. We aimed to objectively compare the efficacy of two-dimensional (2D) versus 3D high-definition endoscopes in novice users. STUDY DESIGN Prospective, randomized crossover study. METHODS Ninety-two novice medical students who used both 2D and 3D endoscopes to complete two validated tasks in a box trainer participated in the study. Time taken and error rates were measured, and subjective data were collected. RESULTS Wilcoxon tests showed 3D technology was significantly faster than 2D (78 vs. 95 seconds, P = .004), and errors per task were significantly lower (3 vs. 5, P < .001). Sixty-nine percent of participants preferred the 3D endoscope. CONCLUSIONS 3D high-definition endoscopy could be instrumental in training the next generation of endoscopic surgeons. Further research is required in a clinical setting. LEVEL OF EVIDENCE 2b Laryngoscope, 129:1280-1285, 2019

Three-Dimensional Endoscopic Endonasal Surgery: A Systematic Review.

OBJECTIVES To compare participant performance and preference in the use of three-dimensional (3D) endoscopy compared to traditional two-dimensional (2D) endoscopy. METHODS PubMed, Embase, Medline, ClinicalKey, BMJ Case Reports, and the Cochrane library were systematically searched for English-language articles published between 2005 and 2020. Studies reporting comparisons of outcomes between 3D and 2D endoscopes were identified. Data relating to performance-related outcomes, as well as the participants' preferred endoscope were extracted, and pooled using meta-analysis models. RESULTS Ten studies were included in the qualitative synthesis. Six studies reported results of participants completing simulated tasks with endoscopes, while four reported full procedures. Peg transfer tasks (n = 4 cohorts) were found to be completed significantly faster with the 3D versus 2D endoscope (pooled mean difference 6.8 seconds, 95% confidence interval [CI]: 2.3-11.3), while no significant difference in times taken was observed for touch tasks (n = 4; pooled mean difference 3.7 seconds, 95% CI: -1.9 to 9.2). The secondary outcome of participant preference was reported by five studies, in which a significant preference for the 3D endoscope was observed (P = .010), with a pooled total of 72% (95% CI: 59-83) of participants preferring this to the 2D endoscope. CONCLUSIONS There is a growing body of evidence in support of 3D visualization in endoscopy. We have demonstrated 3D endoscopy to be associated with a significantly shorter time to performing simulated, reproducible and controlled tasks, and to be the preference of participants. This study provides grounds for further evaluation of the technology, and the potential for a greater widespread use. Laryngoscope, 2021

Breadth and Depth: Three-Dimensional Endoscopic Field of View: Two-Dimensional Versus Three-Dimensional Endoscopic Field of View.

BACKGROUND Three-dimensional (3D) endoscopy is an emerging tool in ear-nose-throat (ENT) and skull base surgery with the benefit of providing real-time depth perception. Several investigators have reported that the field of view (FOV) is reduced in 3D endoscopes compared with regular 2-dimensional (2D) endoscopes. Thus, we objectively compared the FOV of 2D and 3D endoscopes. METHODS Using a standard 2D and 2 different 3D ENT endoscopes, images were captured of 1-mm graph paper from a set distance of 6 cm. The FOV was calculated from these images and compared among the endoscopes. RESULTS The VisionSense 3D endoscope had a slightly smaller FOV (9.1 cm vs. 10.1 cm; -9.9%), and the Karl Storz 3D endoscope showed a slightly larger FOV (10.4 cm vs. 10.1 cm; +3.0%). However, the results were complicated by the different-shaped images produced by the 3D endoscopes. CONCLUSION The differences in the FOV between the 2D and 3D endoscopes used in ENT surgery were not clinically significant. Thus, the FOV should not be considered a limitation of 3D technology

Impaired heart rate recovery and chronotropic incompetence in patients with heart failure with preserved ejection fraction

This study assessed the chronotropic response to exercise and heart rate (HR) recovery after exercise in a carefully phenotyped group of patients with heart failure with preserved left ventricular ejection fraction (HfpEF) and a control group of similar age and gender distribution

Reduced negative surface charge on arterial endothelium explains accelerated atherosclerosis in type 2 diabetic patients

Reduced endothelial surface charge markedly increases the rate of LDL uptake into blood vessels. Previous work in the streptozotocin diabetic rat reported reduced endothelial surface charge. We compared endothelial surface charge density in internal mammary artery rings from patients with type 2 diabetes (n = 12) and from non diabetic patients undergoing coronary artery bypass grafting, and observed a substantial (52%) reduction in the former. This was associated with higher plasma sialic acid levels suggesting loss of sialic acid residues from the glycocalyx as a possible mechanism