Changes In Endothelial Morphology Research Articles

Mycolactone causes destructive Sec61-dependent loss of the endothelial glycocalyx and vessel basement membrane: a new indirect mechanism driving tissue necrosis in Mycobacterium ulcerans infection.

The drivers of tissue necrosis in Mycobacterium ulcerans infection (Buruli ulcer disease) have historically been ascribed solely to the directly cytotoxic action of the diffusible exotoxin, mycolactone. However, its role in the clinically-evident vascular component of disease aetiology remains poorly explained. We have now dissected mycolactone's effects on primary vascular endothelial cells in vitro and in vivo. We show that mycolactone-induced changes in endothelial morphology, adhesion, migration, and permeability are dependent on its action at the Sec61 translocon. Unbiased quantitative proteomics identified a profound effect on proteoglycans, driven by rapid loss of type II transmembrane proteins of the Golgi, including enzymes required for glycosaminoglycan (GAG) synthesis, combined with a reduction in the core proteins themselves. Loss of the glycocalyx is likely to be of particular mechanistic importance, since knockdown of galactosyltransferase II (beta-1,3-galactotransferase 6; B3GALT6), the GAG linker-building enzyme, phenocopied the permeability and phenotypic changes induced by mycolactone. Additionally, mycolactone depleted many secreted basement membrane components and microvascular basement membranes were disrupted in vivo. Remarkably, exogenous addition of laminin-511 reduced endothelial cell rounding, restored cell attachment and reversed the defective migration caused by mycolactone. Hence supplementing mycolactone-depleted extracellular matrix may be a future therapeutic avenue, to improve wound healing rates.

Particularities of Cataract Surgery in Elderly Patients: Corneal Structure and Endothelial Morphological Changes after Phacoemulsification.

The aim of this study was to evaluate the influence of ultrasounds used in phacoemulsification during cataract surgery on the corneal structure and morphology in patients over 65 years. We compared the outcomes of phacoemulsification techniques in terms of corneal cell morphology in 77 patients over 65 years old and 43 patients under 65 years old. Corneal cell density, central corneal thickness and hexagonality were measured preoperatively and post-surgery (at 1 and 4 weeks) by specular microscopy. The effect of gender, axial length and anterior chamber depth on the parameters of corneal endothelium were evaluated. In both groups, a progressive decrease in endothelial cells was observed, starting from the first week post-surgery until the fourth postoperative week. The central corneal thickness increased in both groups with maximum values at the first week postoperatively, while their initial values were restored in the fourth week post-surgery, with no statistical difference between groups. Statistically significant differences were noticed in terms of cell hexagonality in the group over 65, showing smaller hexagonality at all preoperative and postoperative time points compared to group under 65. Our result highlights the importance of routine specular microscopy performed before surgery, regardless the age of the patients, with caution and careful attention to the phaco power intensity, ultrasound energy consumption and intraoperative manipulation of instruments, as well as proper use of viscoelastic substances to reduce corneal endothelium damage, especially in elderly patients.

Corneal endothelial morphology changes in patients with proliferative diabetic retinopathy

Corneal endothelial morphology changes in patients with proliferative diabetic retinopathy

Deep Learning-Based Automatic Diagnosis of Keratoconus with Corneal Endothelium Image.

The primary objective of this study was to develop an end-to-end model that can accurately identify corneal endothelial cells and diagnose keratoconus based on corneal endothelial images acquired from a non-contact specular microscope. This was a retrospective case-control study performed at the Refractive Surgery Center of West China Hospital. A total of 403 keratoconus eyes (221 patients) and 370 myopic eyes (185 normal controls) were consecutively recruited from January 2021 to September 2022. Specular microscopy was used to image and measure the morphometric parameters of the corneal endothelial cells. A Fully Convolutional Network model with a ResNet50 (FCN_ResNet50) was established to perform the endothelial segmentation. The images were then classified using an ensemble machine learning system consisting of four pre-trained deep learning networks: DenseNet121, ResNet50, Inception_v3, and MobileNet_v2. The performance of the models was evaluated based on different metrics, such as accuracy, intersection over union (IoU), and mean IoU. We established a fully end-to-end deep-learning model for the segmentation of endothelial and diagnosis of keratoconus. For endothelial segmentation, the accuracy of the FCN_ResNet50 model achieved near 90% with mean IoU converging to about 80%. The ensemble machine learning system can achieve over 92% accuracy, and > 98% area under curve (AUC) values to diagnose keratoconus with endothelial cell images. In addition, we constructed a diagnostic model based on deep-learning features and developed an associated nomogram which manifested an excellent performance for diagnosis and monitoring the progression of keratoconus. Our research developed an end-to-end model to automatically identify and assess corneal endothelial morphological changes in keratoconus eyes. Moreover, we also constructed a novel nomogram, which can provide valuable information for the diagnosis, monitoring, and management of the disease.

Vascular inflammation on a chip: A scalable platform for trans-endothelial electrical resistance and immune cell migration.

The vasculature system plays a critical role in inflammation processes in the body. Vascular inflammatory mechanisms are characterized by disruption of blood vessel wall permeability together with increased immune cell recruitment and migration. There is a critical need to develop models that fully recapitulate changes in vascular barrier permeability in response to inflammatory conditions. We developed a scalable platform for parallel measurements of trans epithelial electrical resistance (TEER) in 64 perfused microfluidic HUVEC tubules under inflammatory conditions. Over 250 tubules where exposed to Tumor necrosis factor alpha (TNFα) and interferon gamma (INF-γ) or human peripheral blood mononuclear cells. The inflammatory response was quantified based on changes TEER and expression of ICAM and VE-cadherin. We observed changes in barrier function in the presence of both inflammatory cytokines and human peripheral blood mononuclear cells, characterized by decreased TEER values, increase in ICAM expression as well changes in endothelial morphology. OrganoPlate 3-lane64 based HUVEC tubules provide a valuable tool for inflammatory studies in an automation compatible manner. Continuous TEER measurements enable long term, sensitive assays for barrier studies. We propose the use of our platform as a powerful tool for modelling endothelial inflammation in combination with immune cell interaction that can be used to screen targets and drugs to treat chronic vascular inflammation.

Expression of Superoxide Dismutase-1 (SOD-1) and changes of corneal endothelial morphology after phacoemulsification with hypothermic perfusion

Background: Hypothermic perfusion can be used as adjunctive therapy to reduce corneal endothelial cell damage during phacoemulsification procedures. This study aims to evaluate the effect of hypothermic perfusion on the expression of Superoxide Dismutase-1 (SOD1) and morphological changes in the corneal endothelium after ultrasound energy of phacoemulsification exposure. Methods: Sixteen New Zealand white rabbits (n=16 eyes) were randomly divided into two groups and exposed to ultrasound energy of phacoemulsification. The control group was administered room temperature (RT) (24°C) Balanced Salt Solution (BSS) intraocular perfusion, and the treatment group was administered hypothermic (4°C) BSS intraocular perfusion. Coefficient of Variation (CV) and hexagonality were measured before and one day after surgery with specular microscopy. The expression of SOD1 was examined by immunohistochemistry staining. Data were analyzed using SPSS version 26 for Windows. Results: The result showed that the SOD1 expression was significantly lower in the hypothermic perfusion group compared with the control group (p=0.024, p<0.05). There were no significant differences between the two groups in CV changes (p=0.494, p>0.05) and hexagonality changes (p=0.916, p>0.05). There was no correlation between the expression of SOD1 and change in CV (p=0.188, p>0.05) or the expression of SOD1 and change in hexagonality (p=0.763, p>0.05). Conclusion: Hypothermic perfusion suppresses all metabolic processes, including the expression of SOD1 and ROS production. The coefficient of variation and hexagonality as a representative of corneal endothelial morphology changes also decrease with hypothermic perfusion after ultrasound exposure but are not statistically significant. There is no correlation between the expression of SOD1 and changes in CV and hexagonality.

An atypical case of viral endotheliitis

A 48-eight-year-old male presented with redness and blurred vision in his right eye for the past 10 days, sudden in onset, with circumciliary congestion and corneal edema. On examination localized disciform corneal edema, with multiple keratic precipitates, was seen and diagnosed as corneal endotheliitis. Specular microscopy showed endothelial morphological changes with pseudoguttae. Anterior chamber paracentesis subjected to polymerase chain reaction detected varicella zoster virus. He was treated with topical 3% acyclovir gel, homatropine eye drops, 1% prednisolone acetate, and 0.5% timolol maleate. Prednisolone acetate was tapered over 14 weeks. His visual acuity at presentation was 6/36, which improved to 6/9 after 4 weeks of treatment and the final visual acuity was 6/6.

Corneal structure and endothelial morphological changes after uneventful phacoemulsification in type 2 diabetic and nondiabetic patients.

The aim of this study was to compare corneal structure and endothelial morphological changes after uneventful phacoemulsification cataract surgery between type 2 diabetic and nondiabetic patients and to determine the preoperative and intraoperative factors that may predict greater endothelial cell density loss. Forty-five diabetic pa-tients (45 eyes) and 43 controls (43 eyes) with age-related cataract were enrolled in this prospective observational study. Corneal (thickness and volume) and anterior segment parameters were measured by Scheimpflug tomography; endothelial cell density and morphology (coefficient of variation of cell size, hexagonal cells) were recorded using noncontact specular microscopy. Patients were evaluated preoperatively and at one and six months after surgery. Univariate and multivariate linear regression analyses were performed to evaluate the relationship between demographic, clinical, ocular, and intraoperative parameters and postoperative endothelial cell density changes at six months. Significant postoperative endothelial cell loss occurred one month after surgery in both groups (p<0.001), which remained stable until month 6; there were no differences between patients with and without diabetes mellitus at any time point. The mean postoperative central corneal thickness at one and six months did not change significantly from the mean preoperative value in either group (p>0.05). Multivariate linear regression analysis showed that older age (p=0.042) and higher cataract grades (p=0.001) were significantly associated with greater endothelial cell density reduction at six-month follow-up. This study showed that older age and denser cataracts might be associated with greater endothelial cell density reduction after cataract surgery. Other factors, such as diabetes mellitus and preoperative anterior segment parameters, did not influence postoperative changes in endothelial cell density.

The oxidized phospholipid POVPC induces endothelial to mesenchymal transition

The exact mechanisms of atherosclerosis remian unclear. Endothelial to mesenchymal transition (EndMT) plays an important role in atherosclerosis. 1‐Palmitoyl‐2‐(5‐oxovaleroyl)‐sn‐glycero‐3‐phosphocholine (POVPC), the oxidation product of oxidized low‐density lipoprotein, is an oxidized phospholipid and has been found in atherosclerotic lesions. We recently demonstrated that POVPC could impair endothelial function and induce endothelial cell apoptosis. However, the effects of POVPC on EndMT are unclear. Human aortic endothelial cells were treated with POVPC for long term (at least 48 h). Endothelial cell viability and morphology were observed. Nitric oxide (NO) production and superoxide anion generation (O2•−) were measured. The expression of specific endothelial markers cluster of differentiation 31 (CD31) and mesenchymal markers alpha smooth muscle actin (α‐SMA) were detected by immunofluorescence and immunoblotting. The expression of transforming growth factor beta (TGF‐β) and the expression and phosphorylation of Smad were also determined. Finally, endothelial cell migration was tested. POVPC did not affect the endothelial cell viability, but induce the cellular morphology transformation from cobblestone‐like endothelial cells into spindle‐like mesenchymal cells. POVPC decreased NO production and increased O2•− generation, which inhibited by NG‐nitro‐L‐arginine methylester (L‐NAME). POVPC also inhibited expression of CD31, but stimulated the expression of α‐SMA and TGF‐β as well as the phosphorylation of Smad, which partially inhibited by L‐NAME. Long term POVPC treatment promoted endothelial cell migration. These data demonstrated that POVPC could induce the changes in endothelial morphology and could uncouple eNOS activity to generate O2•− to increase oxidative stress, which may stimulate the expression and phosphorylation of TGF‐β/Smad to mediate the occurrence of EndMT. These effects may promote fibrosis remodel and spindle‐like mesenchymal cell migration to accelerate the process of atherosclerosis.Support or Funding InformationNational Natural Science Foundation of China (Grants 81370370, 81670392, 81600382 and Distinguished Young Scholar Grant 81325001), International cooperation project(2015DFA31070) and National Major Research Program (2016YFC0903000) from the Ministry of Science and Technology of China, Guangdong Natural Science Fund Committee (Grant 2015A030312009), the Changjiang Scholars Program from the Ministry of Education of China, the Guangdong Pearl River Scholars Program, the Sun Yat‐sen University Clinical Research 5010 Program.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Enhanced adhesion of blood platelets to intact endothelium of mesenteric vascular bed in mice with streptozotocin-induced diabetes is mediated by an up-regulated endothelial surface deposition of VWF – In vivo study

Numerous in vitro experiments have confirmed that a dysfunctional endothelium is characterized by, inter alia, a higher affinity for binding of platelets and leukocytes. However, there is still no direct evidence for greater interaction between platelets and intact endothelium in in vivo animal models of diabetes. Therefore, the present study examines the pro-adhesive properties of endothelium change in vivo as an effect of streptozotocin (STZ)-induced diabetes and the role of two key platelet receptors: GPIb-IX-V and GPIIb/IIIa.Mice of C57BL strain with streptozotocin-induced diabetes were used in the study. Flow cytometry was used to assess basal activation and reactivity of platelets. Adhesion of platelets to the vascular wall was visualized with the use of intravital microscopy in mesentery. The contribution of GPIIb/IIIa and GPIb-IX-V was evaluated by the injection of Fab fragments of respective antibodies. The integrity of the endothelium and vWf expression were evaluated histochemically.Basal activation and reactivity of platelets in streptozotocin-diabetic mice were elevated. Blood platelets adhered more often to the vascular wall of diabetic mice than nondiabetic animals: 11.9 (6.4; 32.8) plt/min/mm2 (median [IQR]) vs 2.7 (1.3; 6.4) plt/min/mm2. The injection of anti-GPIbα antibodies decreased the number of adhering platelets from 89.5 (34.0; 113.1) plt/min/mm2 (median [IQR]) in mice treated with isotype antibodies to 3.1 (1.7; 5.6) plt/min/mm2 in mice treated with blocking antibodies. The effect of GPIIb/IIIa blockage was not significant. Immunohistochemistry revealed a higher expression of vWF in the endothelium of STZ mice, but no substantial changes in endothelial morphology were detected.To conclude, the study shows that the platelets interact more frequently with the mesenteric vascular bed in mice with 1-month STZ-induced diabetes than in healthy mice. These interactions are mediated via platelet GPIb-IX-V and are driven by increased expression of vWF in endothelial cells.

Review of the endothelial pathogenic mechanism of TIE2-related venous malformation

Venous malformation (VM) is a type of disease involving vascular morphogenesis in humans. Clinically, VM can be sporadic or inherited. TIE2, also known as TEK or HYK, is a member of the receptor tyrosine kinase subfamily and is highly conserved among species. In 1996, an arginine-to-tryptophan substitution at position 849 (R849W) in TIE2 was found to induce hereditary VM. Additional alterations in TIE2 involved in the pathogenesis of inherited or sporadic VM have since been reported. The relevant key literature was selectively reviewed, including case reports, reviews, research studies, and meta-analyses. TIE2 can be thought of as the basis for VM, with a potential role in determining locations, through intracorporal endothelium-specific distribution and expression from the embryonic phase. It has a sophisticated protein structure, and various point mutations destroy its function and physiologic processes by obviously different activation mechanisms, of which some inhibit dephosphorylation and others maintain phosphorylation. Extracellularly, whereas angiopoietins (ANGs) are ligands of TIE2, the chaotic balance between ANG1 and ANG2 in VM is related to their effects on switching between the cell-cell/cell-extracellular matrix contact conditions and vascular quiescence/angiogenesis state, resulting in corrupted contacts. Intracellularly, among diverse cellular pathways, phosphatidylinositol 4,5-bisphosphate 3-kinase/AKT serine-threonine kinase, mitogen-activated protein kinase, and Dok-related protein are irreplaceable keys underlying changes in endothelial morphology and behavioral biology in VM. For example, R849W and L914F (a leucine-to-phenylalanine substitution at position 914), the most important and frequent TIE2 mutations associated with VM, share similar phenotypes but differ with respect to signaling pathways, heredity, and triggering factors. Based on this comprehensive analysis, we propose an avalanche theory, in which mutant TIE2 is a trigger and pathogenic core, the intercellular network is a tool, altered extracellular matrix and contacts are the final foothold, and fragile contacts are the result. Precise classification according to TIE2 mutation type in VM, especially the mutation site, is important for future targeted therapies.

Reduced nitric oxide bioavailability mediates cerebroarterial dysfunction independent of cerebral amyloid angiopathy in a mouse model of Alzheimer’s disease

We show that vasorelaxation of the basilar artery, a large intracranial, extracerebral artery important for cerebral perfusion, is impaired independent of cerebral amyloid angiopathy in a transgenic mouse model of Alzheimer's disease. Interestingly, this dysfunction is specifically endothelium related and is mediated by impaired nitric oxide-cyclic GMP bioavailability.

Flow shear stress regulates endothelial barrier function and expression of angiogenic factors in a 3D microfluidic tumor vascular model

Endothelial cells lining blood vessels are exposed to various hemodynamic forces associated with blood flow. These include fluid shear, the tangential force derived from the friction of blood flowing across the luminal cell surface, tensile stress due to deformation of the vessel wall by transvascular flow, and normal stress caused by the hydrodynamic pressure differential across the vessel wall. While it is well known that these fluid forces induce changes in endothelial morphology, cytoskeletal remodeling, and altered gene expression, the effect of flow on endothelial organization within the context of the tumor microenvironment is largely unknown. Using a previously established microfluidic tumor vascular model, the objective of this study was to investigate the effect of normal (4 dyn/cm2), low (1 dyn/cm2), and high (10 dyn/cm2) microvascular wall shear stress (WSS) on tumor-endothelial paracrine signaling associated with angiogenesis. It is hypothesized that high WSS will alter the endothelial phenotype such that vascular permeability and tumor-expressed angiogenic factors are reduced. Results demonstrate that endothelial permeability decreases as a function of increasing WSS, while co-culture with tumor cells increases permeability relative to mono-cultures. This response is likely due to shear stress-mediated endothelial cell alignment and tumor-VEGF-induced permeability. In addition, gene expression analysis revealed that high WSS (10 dyn/cm2) significantly down-regulates tumor-expressed MMP9, HIF1, VEGFA, ANG1, and ANG2, all of which are important factors implicated in tumor angiogenesis. This result was not observed in tumor mono-cultures or static conditioned media experiments, suggesting a flow-mediated paracrine signaling mechanism exists with surrounding tumor cells that elicits a change in expression of angiogenic factors. Findings from this work have significant implications regarding low blood velocities commonly seen in the tumor vasculature, suggesting high shear stress-regulation of angiogenic activity is lacking in many vessels, thereby driving tumor angiogenesis.

Light microscopy of the corneal pathologies that we meet in our daily practice as an eye banker

AbstractPurpose Organ culture is the method of choice for the preservation of a human donor cornea for transplantation throughout Europe. This method is often closely connected with the assessment of the cornea using light microscopy. The corneal endothelium, its polymeghatism, pleomorphism, cornea guttata and other endothelial abnormalities as well as epithelial and stromal pathologies will be presented to show the usefulness of light microscopy in the evaluation of corneal pathologies.Methods Photographs from light microscopy (both phase contrast and bright field) taken before and after corneal storage in organ culture will be compared and discussed in relation to changes in endothelial morphology and the swelling of the intercellular spaces. The individual corneal layers (the corneal epithelium, the stroma and the endothelium) of pathological corneas will be compared to those of control corneas.Results Among corneal pathologies, cornea guttata, corneal dystrophies (Fuchs endothelial corneal dystrophy, posterior polymorphous corneal dystrophy) and crystalline keratopathy will be shown using pathological explants. Moreover, the corneal pathologies will be correlated with histological findings. Finally, bacterial and fungal contamination of the cornea during organ culture will be shown.Conclusion Light microscopy is an essential part of qualitative and quantitative corneal assessment, which allows corneas with a variety of pathologies, mostly endothelial in origin, to be excluded from grafting. This work was supported by the project PRVOUK‐P24LF13 of Charles University in Prague.

The role of microRNAs in neural stem cell-supported endothelial morphogenesis

Functional signaling between neural stem/progenitor cells (NSPCs) and brain endothelial cells (ECs) is essential to the coordination of organized responses during initial embryonic development and also during tissue repair, which occurs following brain injury. In this study, we investigated the molecular mechanisms underlying this functional signaling, using primary mouse brain ECs and NSPCs from embryonic mouse brain. EC/NSPC co-culture experiments have revealed that neural progenitors secrete factors supporting angiogenesis, which induce noticeable changes in endothelial morphology. We demonstrate that NSPCs influence the expression of mTOR and TGF-β signaling pathway components implicated in the regulation of angiogenesis. Endothelial morphogenesis, an essential component of vascular development, is a complex process involving gene activation and the upregulation of specific cell signaling pathways. Recently identified small molecules, called microRNAs (miRNAs), regulate the expression of genes and proteins in many tissues, including brain and vasculature. We found that NSPCs induced considerable changes in the expression of at least 24 miRNAs and 13 genes in ECs. Three NSPC-regulated EC miRNAs were identified as the potential primary mediators of this NSPC/EC interaction. We found that the specific inhibition, or overexpression, of miRNAs miR-155, miR-100, and miR-let-7i subsequently altered the expression of major components of the mTOR, TGF-β and IGF-1R signaling pathways in ECs. Overexpression of these miRNAs in ECs suppressed, while inhibition activated, the in vitro formation of capillary-like structures, a process representative of EC morphogenesis. In addition, we demonstrate that inhibition of FGF, VEGF, and TGF-β receptor signaling abolished NSPC-promoted changes in the endothelial miRNA profiles. Our findings demonstrate that NSPCs induce changes in the miRNA expression of ECs, which are capable of activating angiogenesis by modulating distinct cell signaling pathways.

Roles of Rho/ROCK and MLCK in TNF‐α‐induced changes in endothelial morphology and permeability

Tumor necrosis factor-alpha (TNF-alpha) is known to induce changes in endothelial cell morphology and permeability, but the mechanisms have not been extensively characterized. TNF-alpha rapidly induced RhoA activation and myosin light chain phosphorylation, but caused only small changes to cortical F-actin, without significantly increasing paracellular permeability up to 30 min after stimulation. TNF-alpha subsequently caused a progressive increase in permeability and in stress fiber reorganization, cell elongation, and intercellular gap formation over 8-24 h. Consistent with the increased permeability, Occludin and JAM-A were removed from tight junctions and ZO-1 was partially redistributed. Rho/ROCK but not MLCK inhibition prevented the long-term TNF-alpha-induced changes in F-actin and cell morphology, but ROCK inhibition did not affect permeability. These results suggest that the gradual increase in permeability induced by TNF-alpha does not reflect contractile mechanisms mediated by Rho, ROCK, and MLCK, but involves long-term reorganization of tight junction proteins.

Differential gene and protein expression in abluminal sprouting and intraluminal splitting forms of angiogenesis

In adult skeletal muscle, abluminal sprouting or longitudinal splitting of capillaries can be initiated separately by muscle overload and elevated microcirculation shear stress respectively. In the present study, gene and protein expression patterns associated with the different forms of angiogenesis were examined using a targeted gene array (Superarray), validated by quantitative RT (reverse transcription)-PCR and immunoblots. Sprouting angiogenesis induced large changes in expression levels in genes associated with extracellular matrix remodelling, such as MMP-2 (matrix metalloproteinase-2), TIMP (tissue inhibitor of metalloproteinases), SPARC (secreted protein, acidic and rich in cysteine) and thrombospondin. Changes in neuropilin, midkine and restin levels, which may underpin changes in endothelial morphology, were seen during splitting angiogenesis. Up-regulation of VEGF (vascular endothelial growth factor), Flk-1, angiopoietin-2 and PECAM-1 (platelet/endothelial cell adhesion molecule-1) was seen in both forms of angiogenesis, representing a common angiogenic response of endothelial cells. In conclusion, the present study demonstrates that general angiogenic signals from growth factors can be influenced by the local microenvironment resulting in differing forms of capillary growth to produce a co-ordinated expansion of the vascular bed.

Continuous Visualization of Morphological Changes in Endothelial Cells in Response to Cyclic Stretch

Endothelial cells are known to change their shapes in alignment with the direction perpendicular to that of cyclic stretch. However, the mechanisms are still not clear. In this study, we developed a new cell-stretching device which allows continuous observation of cyclically stretched/relaxed cells. Using this apparatus, morphological changes of single cells in response to cyclic stretch (1Hz, 10%, 2 hours) were visualized and analyzed. The data showed that there were two major patterns of morphological changes of ECs, depending on their initial shapes. While ECs with round shapes at the initial state changed their shapes to become more elongated in a direction perpendicular to that of stretch, cells oriented and elongated in the stretch direction at the initial state changed their shapes to first become rounder and then elongated to align perpendicular to the stretch direction at the second step. These results suggest that cell retraction as well as elongation is important in the stretch-induced endothelial morphological changes, and that the elucidation of the mechanisms of the morphological changes requires studies of cell retraction, elongation, and their coordination at the single-cell level.

Endothelial Glycocalyx as an Additional Barrier Determining Extravasation of 6% Hydroxyethyl Starch or 5% Albumin Solutions in the Coronary Vascular Bed

The impact on the endothelial glycocalyx for the extravasation of colloidal infusion solutions has not been investigated sufficiently. Isolated guinea pig hearts were perfused with Krebs-Henseleit buffer in a Langendorff mode. Solutions of 0.9% saline, 5% albumin (70 kd), or 6% hydroxyethyl starch (200 kd) were infused into the coronary system for 20 min at a rate of one third of the coronary flow, also during reperfusion after 15 min of ischemia, and after enzymatic digestion of the endothelial glycocalyx by heparinase. Net coronary fluid filtration was assessed directly by measuring the formation of transudate on the epicardial surface, and solute extravasation was assessed by measuring albumin and hydroxyethyl starch in the coronary effluent and transudate. Hearts were perfusion fixed to visualize the endothelial glycocalyx using transmission electron microscopy. Only infusion of hydroxyethyl starch, not infusion of albumin, significantly decreased net coronary fluid filtration. Heparinase application without ischemia increased coronary leak by 25% but did not accelerate the passage of colloids. Ischemia alone did not alter permeability. However, there was a large (approximately +200%), transient (approximately 4 min) increase in permeability for water, albumin, and hydroxyethyl starch after ischemia with heparinase application. Also, histamine (10 m) only increased permeability after pretreatment of the hearts with heparinase. The thickness of the glycocalyx after colloid administration was 0.2-0.3 microm. No glycocalyx could be detected after application of heparinase. The endothelial glycocalyx acts as a competent barrier for water and colloids. Only after its destruction do changes in endothelial morphology (postischemic reperfusion or histamine application) become effective determinants of coronary extravasation.

Evaluation of corneal damage by combined phacoemulsification and passive efflux of silicone oil in vitrectomized eyes

Purpose To evaluate the effect on the corneal endothelium of phacoemulsification combined with passive silicone oil removal and intraocular lens (IOL) implantation under topical anesthesia after pars plana vitrectomy. Setting Department of Ophthalmology and Otolaryngology, University of Bari, Bari, Italy. Methods This retrospective study evaluated the corneal endothelium in 17 consecutive patients (17 eyes) who had phacoemulsification with transpupillary passive silicone oil washout (1300 centistokes) through a posterior capsulorhexis and single clear corneal incision and foldable acrylic IOL implantation. The findings were compared with those in a control group of 17 patients (17 eyes) who had phacoemulsification with acrylic IOL implantation through a single clear corneal incision. All procedures were performed by the same surgeon using topical anesthesia. The preoperative and postoperative endothelial cell densities, coefficient of variation (CV), and percentage of hexagonal cells at the corneal center and peripheral temporal position, evaluated by noncontact specular microscopy, were compared between the 2 groups. The central corneal thickness and occurrence of keratopathy were also noted. Results The mean phacoemulsification and total ultrasound times did not differ significantly between the 2 groups. At 6 months, the mean endothelial cell loss was 284.50 cell/mm 2 ± 462.3 (SD) (11.2%) in the study group and 200.15 ± 117.9 cell/mm 2 (8.3%) in the control group ( P=.87, unpaired t test). There were no significant between-group differences in the increase in the mean CV and the percentage of hexagonal cells. The mean pachymetry remained at preoperative values, with no difference between groups. Keratopathy was not observed in any patient. Conclusions Passive silicone oil efflux caused significant endothelial cell loss and changes in endothelial morphology. Nevertheless, these modifications were well tolerated and minimally different from the results of trauma caused by standard phacoemulsification with posterior chamber IOL implantation.