Endothelial Surface Layer Degradation by Chronic Hyaluronidase Infusion Induces Proteinuria in Apolipoprotein E-Deficient Mice

Functional studies show that disruption of endothelial surface layer (ESL) is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL through enzymatic degradation would affect vascular barrier properties in an atherogenic model. Eight week old male apolipoprotein E deficient mice on Western-type diet for 10 weeks received continuous active or heat-inactivated hyaluronidase (10 U/hr, i.v.) through an osmotic minipump during 4 weeks. Blood chemistry and anatomic changes in both macrovasculature and kidneys were examined. Infusion with active hyaluronidase resulted in decreased ESL (0.32±0.22 mL) and plasma volume (1.03±0.18 mL) compared to inactivated hyaluronidase (0.52±0.29 mL and 1.28±0.08 mL, p<0.05 respectively).Active hyaluronidase increased proteinuria compared to inactive hyaluronidase (0.27±0.02 vs. 0.15±0.01 µg/µg protein/creatinin, p<0.05) without changes in glomerular morphology or development of tubulo-interstitial inflammation. Atherosclerotic lesions in the aortic branches showed increased matrix production (collagen, 32±5 vs. 18±3%; glycosaminoglycans, 11±5 vs. 0.1±0.01%, active vs. inactive hyaluronidase, p<0.05). ESL degradation in apoE deficient mice contributes to reduced increased urinary protein excretion without significant changes in renal morphology. Second, the induction of compositional changes in atherogenic plaques by hyaluronidase point towards increased plaque vulnerability. These findings support further efforts to evaluate whether ESL restoration is a valuable target to prevent (micro) vascular disease progressio

International Survey on Mechanical Ventilation During Extracorporeal Membrane Oxygenation

The optimal ventilation strategy for patients on extracorporeal membrane oxygenation (ECMO) remains uncertain. This survey reports current mechanical ventilation strategies adopted by ECMO centers worldwide. An international, multicenter, cross-sectional survey was conducted anonymously through an internet-based tool. Participants from North America, Europe, Asia, and Oceania were recruited from the extracorporeal life support organization (ELSO) directory. Responses were received from 48 adult ECMO centers (response rate 10.6%). Half of these had dedicated ventilation protocols for ECMO support. Pressure-controlled ventilation was the preferred initial ventilation mode for both venovenous ECMO (VV-ECMO) (60%) and venoarterial ECMO (VA-ECMO) (34%). In VV-ECMO, the primary goal was lung rest (93%), with rescue therapies commonly employed, especially neuromuscular blockade (93%) and prone positioning (74%). Spontaneous ventilation was typically introduced after signs of pulmonary recovery, with few centers using it as the initial mode (7%). A quarter of centers stopped sedation within 3 days after ECMO initiation. Ventilation strategies during VA-ECMO focused less on lung-protective goals and transitioned to spontaneous ventilation earlier. Ventilation strategies during ECMO support differ considerably. Controlled ventilation is predominantly used initially to provide lung rest, often facilitated by sedation and neuromuscular blockade. Few centers apply "awake ECMO" early during ECMO support, some utilizing partial neuromuscular blockade.</p

International Survey on Mechanical Ventilation During Extracorporeal Membrane Oxygenation

The optimal ventilation strategy for patients on extracorporeal membrane oxygenation (ECMO) remains uncertain. This survey reports current mechanical ventilation strategies adopted by ECMO centers worldwide. An international, multicenter, cross-sectional survey was conducted anonymously through an internet-based tool. Participants from North America, Europe, Asia, and Oceania were recruited from the extracorporeal life support organization (ELSO) directory. Responses were received from 48 adult ECMO centers (response rate 10.6%). Half of these had dedicated ventilation protocols for ECMO support. Pressure-controlled ventilation was the preferred initial ventilation mode for both venovenous ECMO (VV-ECMO) (60%) and venoarterial ECMO (VA-ECMO) (34%). In VV-ECMO, the primary goal was lung rest (93%), with rescue therapies commonly employed, especially neuromuscular blockade (93%) and prone positioning (74%). Spontaneous ventilation was typically introduced after signs of pulmonary recovery, with few centers using it as the initial mode (7%). A quarter of centers stopped sedation within 3 days after ECMO initiation. Ventilation strategies during VA-ECMO focused less on lung-protective goals and transitioned to spontaneous ventilation earlier. Ventilation strategies during ECMO support differ considerably. Controlled ventilation is predominantly used initially to provide lung rest, often facilitated by sedation and neuromuscular blockade. Few centers apply "awake ECMO" early during ECMO support, some utilizing partial neuromuscular blockade.</p

The endothelial glycocalyx: a potential barrier between health and vascular disease

PURPOSE OF REVIEW: Although cardiovascular prevention has improved substantially, we still face the challenge of finding new targets to reduce the sequelae of atherosclerosis further. In this regard, optimizing the vasculoprotective effects of the vessel wall itself warrants intensive research. In particular, the endothelial glycocalyx, consisting of proteoglycans, glycoproteins and adsorbed plasma proteins, may play an essential role in protecting the vessel wall from atherosclerosis. RECENT DEVELOPMENTS: In this review, we will discuss the different vasculoprotective effects exerted by the endothelial glycocalyx, the factors that damage it, and the first preliminary data on the glycocalyx dimension in humans. Whereas most glycocalyx research has traditionally focused on the microvasculature, more recent data have underscored the importance of the glycocalyx in protecting the macrovasculature against pro-atherogenic insults. It has been shown that glycocalyx loss is accompanied by a wide array of unfavourable changes in both small and larger vessels. Pro-atherogenic stimuli increase the shedding of glycocalyx constituents into the circulation, contributing to the progressive loss of the vasculoprotective properties of the vessel wall. Novel techniques have facilitated reproducible measurements of systemic glycocalyx volume in humans. Consistent with experimental data, the volume of the human glycocalyx is also severely perturbed by exposure to atherogenic risk factors. SUMMARY: Cumulating evidence suggests that an intact glycocalyx protects the vessel wall, whereas disruption of the glycocalyx upon atherogenic stimuli increases vascular vulnerability for atherogenesi

Plasma concentrations of ascorbic acid and C-reactive protein, and risk of future coronary artery disease, in apparently healthy men and women:the EPIC-Norfolk prospective population study

High plasma concentrations of ascorbic acid, a marker of fruit and vegetable intake, are associated with low risk of coronary artery disease. Whether this relationship is explained by a reduction in systemic inflammation is unclear. We investigated the relationship between ascorbic acid plasma concentration and coronary artery disease risk, and in addition whether this relationship depended on classical risk factors and C-reactive protein (CRP) concentration. We used a prospective nested case-control design. The study consisted of 979 cases and 1794 controls (1767 men and 1006 women). Increasing ascorbic acid quartiles were associated with lower age, BMI, systolic and diastolic blood pressure, and CRP concentration, but with higher HDL-cholesterol concentration. No associations existed between ascorbic acid concentration and total cholesterol concentration or LDL-cholesterol concentration. When data from men and women were pooled, the risk estimates decreased with increasing ascorbic acid quartiles such that people in the highest ascorbic acid quartile had an odds ratio for future coronary artery disease of 0.67 (95 % CI 0.52, 0.87) compared with those in the lowest quartile (P for linearity=0.001). This relationship was independent of sex, age, diabetes, smoking, BMI, LDL-cholesterol, HDL-cholesterol, systolic blood pressure and CRP level. These data suggest that the risk reduction associated with higher ascorbic acid plasma concentrations, a marker of fruit and vegetable intake, is independent of classical risk factors and also independent of CRP concentration

Measurement of carotid intima-media thickness to assess progression and regression of atherosclerosis

Imaging modalities have been developed to assess atherosclerosis in vivo in the arterial wall because large clinical end-point studies are time-consuming and costly. Historically, in-hospital angiography and Doppler ultrasonography have been used to assess atherosclerosis development. Investigations of the arterial lumen are, however, increasingly being replaced by modalities that can measure changes in the arterial wall itself-intravascular ultrasonography, MRI and multislice CT. The fact that intravascular ultrasonography is invasive, CT involves substantial radiation exposure and requires contrast agents, and that MRI is time-consuming and technically challenging all limit the widespread use of these techniques. Moreover, all modalities have high associated costs. B-mode ultrasonographic imaging of the carotid arterial walls occupies a unique position in atherosclerosis research. This method enables sensitive, reproducible and noninvasive assessment of intima-media thickness (IMT) as a continuous variable. Epidemiological and clinical trial evidence as well as digitization and standardization have made carotid IMT a validated and accepted marker for generalized atherosclerosis burden and vascular disease risk. Here we describe the application of carotid IMT measurements as a tool in risk evaluation of individuals and in studies of atherosclerosis progression and regressio

Partial recovery of the endothelial glycocalyx upon rosuvastatin therapy in patients with heterozygous familial hypercholesterolemia

Objective: The endothelial glycocalyx has been shown to serve as a protective barrier between the flowing blood and the vessel wall in experimental models. The aim of this study was to evaluate whether hypercholesterolemia is associated with glycocalyx perturbation in humans, and if so, whether statin treatment can restore this. Methods/Results: We measured systemic glycocalyx volume (VG) in 13 patients with heterozygous familial hypercholesterolemia (FH) after cessation of lipid-lowering therapy for a minimum of 4 weeks and 8 weeks after initiating rosuvastatin therapy. Normocholesterolemic subjects were used as controls. VG was estimated by subtracting the intravascular distribution volume of a glycocalyx permeable tracer (dextran 40) from that of a glycocalyx impermeable tracer (labeled erythrocytes). VG in untreated FH patients (LDL 225 +/- 57 mg/dL (mean+/-SD)) was significantly reduced compared to controls (LDL 93 +/- 24 mg/dL) (VG 0.8 +/- 0.3 L vs. 1.7 +/- 0.6 L respectively, p < 0.001). After normalization of LDL levels (95 +/- 33 mg/dL) upon 8 weeks of statin treatment, VG recovered only partially (VG 1.1 +/- 0.4 L, p = 0.04). Conclusions: The endothelial glycocalyx is profoundly reduced in FH patients, which may contribute to increased atherogenic vulnerability. This perturbation is partially restored upon short-term statin therap

Diabetes mellitus type 2 is associated with higher levels of myeloperoxidase

BACKGROUND: Diabetes mellitus type 2 is linked to augmented endothelial dysfunction and accelerated atherosclerosis. Myeloperoxidase plays an important role in the initiation, progression, and the complications of atherosclerosis. We investigated whether myeloperoxidase levels are increased in diabetic patients. MATERIAL/METHODS: We compared baseline plasma myeloperoxidase levels in diabetic and nondiabetic patients with mild, stable anginal complaints (Canadian Cardiovascular Society I-II/IV) and performed multivariate linear regression analyses to adjust for possible confounding factors. RESULTS: A total of 440 patients were recruited from the outpatient clinic of cardiology, 268 patients with and 172 without diabetes mellitus type 2. Levels of myeloperoxidase were significantly higher in diabetic patients (median, 141 pM; interquartile range, 115-171 pM) than in nondiabetic patients (median, 126 pM; interquartile range, 105-167 pM) (P=0.01). Diabetes mellitus type 2, age in years, current smoking status, presence of hypercholesterolemia, and use of calcium antagonists and ACE inhibitors were associated with logarithmically transformed myeloperoxidase levels. Of these variables, diabetes mellitus type 2 (beta 0.096, SE 0.038, P=0.01); age (beta 0.01, SE 0.002, P <0.001), and current smoking (beta 0.166, SE 0.05, P=0.001) remained independently associated with myeloperoxidase levels in multivariate analysis. The linear regression coefficient of diabetes mellitus type 2 in relation to myeloperoxidase was 0.092 in univariate linear regression and 0.078 after adjusting for age, current smoking, and use of ACE inhibitors and calcium antagonists. CONCLUSIONS: Diabetes mellitus type 2 is associated with mildly increased levels of myeloperoxidase, independent of other clinical variables. This association may contribute to the accelerated progression of atherosclerosis in diabetic

Measuring endothelial glycocalyx dimensions in humans: a potential novel tool to monitor vascular vulnerability

The endothelial glycocalyx is increasingly considered as an intravascular compartment that protects the vessel wall against pathogenic insults. The purpose of this study was to translate an established experimental method of estimating capillary glycocalyx dimension into a clinically useful tool and to assess its reproducibility in humans. We first evaluated by intravital microscopy the relation between the distance between the endothelium and erythrocytes, as a measure of glycocalyx thickness, and the transient widening of the erythrocyte column on glycocalyx compression by passing leukocytes in hamster cremaster muscle capillaries. We subsequently assessed sublingual microvascular glycocalyx thickness in 24 healthy men using orthogonal polarization spectral imaging. In parallel, systemic glycocalyx volume (using a previously published tracer dilution technique) as well as cardiovascular risk profiles were assessed. Estimates of microvascular glycocalyx dimension from the transient erythrocyte widening correlated well with the size of the erythrocyte-endothelium gap (r = 0.63). Measurements in humans were reproducible (0.58 +/- 0.16 and 0.53 +/- 0.15 microm, coefficient of variance 15 +/- 5%). In univariate analysis, microvascular glycocalyx thickness significantly correlated with systemic glycocalyx volume (r = 0.45), fasting plasma glucose (r = 0.43), and high-density lipoprotein-cholesterol (r = 0.40) and correlated negatively with low-density lipoprotein-cholesterol (r = -0.41) as well as body mass index (r = -0.45) (all P < 0.05). In conclusion, the dimension of the endothelial glycocalyx can be measured reproducibly in humans and is related to cardiovascular risk factors. It remains to be tested whether glycocalyx dimension can be used as an early marker of vascular damage and whether therapies aimed at glycocalyx repair can protect the vasculature against pathogenic challenge