Soluble Urokinase Plasminogen Activator Receptor Levels Are Associated with Severity of Fibrosis in Patients with Primary Sclerosing Cholangitis.

The soluble urokinase-type plasminogen activator receptor (suPAR) has evolved as a useful biomarker for different entities of chronic liver disease. However, its role in patients with primary sclerosing cholangitis (PSC) is obscure. We analyzed plasma levels of suPAR in 84 patients with PSC and compared them to 68 patients with inflammatory bowel disease (IBD) without PSC and to 40 healthy controls. Results are correlated with clinical records. suPAR concentrations were elevated in patients with PSC compared to patients with IBD only and to healthy controls (p < 0.001). Elevated suPAR levels were associated with the presence of liver cirrhosis (p < 0.001) and signs of portal hypertension (p < 0.001). suPAR revealed a high accuracy for the discrimination of the presence of liver cirrhosis comparable to previously validated noninvasive fibrosis markers (area under the curve (AUC) 0.802 (95%CI: 0.702−0.902)). Further, we demonstrated that suPAR levels may indicate the presence of acute cholangitis episodes (p < 0.001). Finally, despite the high proportion of PSC patients with IBD, presence of IBD and its disease activity did not influence circulating suPAR levels. suPAR represents a previously unrecognized biomarker for diagnosis and liver cirrhosis detection in patients with PSC. However, it does not appear to be confounded by intestinal inflammation in the context of IBD.

Shear Wave Elastography in the Detection of Sinusoidal Obstruction Syndrome in Adult Patients Undergoing Allogenic Hematopoietic Stem Cell Transplantation.

Hepatic sinusoidal obstruction syndrome (SOS), also known as veno-occlusive disease (VOD) can be a life-threatening complication after hematopoietic stem cell transplantation (HSCT). Diagnosis is often difficult and traditionally based on clinical parameters. Shear wave elastography (SWE) is a modern non-invasive liver stiffness measurement technique using ultrasound. In this monocentric study, we evaluated the role of SWE in diagnosing SOS/VOD in 63 adult patients undergoing HSCT from February 2020 to August 2020 in real world settings. Three patients developed SOS/VOD. This was accompanied by an increase in shear wave velocity in all three patients, indicating that this method may contribute to establishing the diagnosis SOS/VOD after HSCT.

Gap junctions regulate vessel diameter in chick chorioallantoic membrane vasculature by both tone-dependent and structural mechanisms.

OBJECTIVE: In this study, we examined the impact of gap junction blockade on chick chorioallantoic membrane microvessels. METHODS: Expression of Cx37, Cx40/42, and Cx43 in chick chorioallantoic membrane tissue was studied by PCR, Western blot, and confocal immunofluorescence microscopy. Vessel diameter changes occurring under gap junction blockade with carbenoxolone (175 µmol/L), palmitoleic acid (100 µmol/L), 43 GAP27 (1 mmol/L) were analyzed by intravital microscopy. To analyze vascular tone, chick chorioallantoic membrane vessels were exposed to a vasodilator cocktail consisting of acetylcholine (10 µmol/L), adenosine (100 µmol/L), papaverine (200 µmol/L), and sodium nitroprusside (10 µmol/L). RESULTS: In chick chorioallantoic membrane lysates, Western blot analysis revealed the expression of Cx40 and Cx43. Immunofluorescence in intact chick chorioallantoic membrane vasculature showed only Cx43, limited to arterial vessel walls. Upon gap junction blockade (3 hours) arterial and venous diameters decreased to 0.50 ± 0.03 and 0.36 ± 0.06 (carbenoxolone), 0.72 ± 0.08 and 0.63 ± 0.15 (palmitoleic acid) and 0.77 ± 0.004 and 0.58 ± 0.05 (GAP27), relative to initial values. Initially, diameter decrease was dominated by increasing vascular tone. After 6 hours, however, vessel tone was reduced, suggesting structural network remodeling. CONCLUSIONS: Our findings suggest a major role for connexins in mediating acute and chronic diameter changes in developing vascular networks.

Dynamic remodeling of arteriolar collaterals after acute occlusion in chick chorioallantoic membrane.

OBJECTIVE: After arteriolar occlusion, collaterals enlarge and initially elevated WSS normalizes. While most previous studies focused on endpoints of such adaptive changes in larger collaterals, the present investigation aimed to continuously determine the relation between WSS and diameter in microvascular collaterals during adaptive reactions. METHODS: In Hamburger-Hamilton stage 40 CAMs, junction points between arteriolar segments were identified and the third upstream segment on one side was occluded. Intravital microscopy recordings were taken for 24 hours post-occlusion. Segment diameter and blood velocity were measured: WSS and capillary density were calculated. RESULTS: After occlusion, vascular diameters exhibited an immediate decrease, then increased with a time constant of 2.5 ± 0.8 hours and reached a plateau of up to 60% above baseline after about 7 hours. Vascular tone showed no significant change. WSS exhibited an immediate increase post-occlusion and linearly returned to baseline after about 12 hours. Local WSS change and diameter change rate showed similar patterns during the initial but not the later phase of post-occlusive adaptation. CONCLUSIONS: CAM collaterals undergo fast structural remodeling within 24 hours post-occlusion. This remodeling might be driven by local WSS and by other regulators within the vascular network.

Microvascular hemodynamics in the chick chorioallantoic membrane.

OBJECTIVE: The microvasculature of the CAM in the developing chick embryo is characterized by interdigitating arteriolar and venular trees, connected at multiple points along their lengths to a mesh-like capillary plexus. Theoretical modeling techniques were employed to investigate the resulting hemodynamic characteristics of the CAM. METHODS: Based on previously obtained anatomical data, a model was developed in which the capillary plexus was treated as a porous medium. Supply of blood from arterioles and drainage into venules were represented by distributions of flow sources and sinks. Predicted flow velocities were compared with measurements in arterioles and venules obtained via video microscopy. RESULTS: If it was assumed that blood flowed into and out of the capillary plexus only at the ends of terminal arterioles and venules, the predicted velocities increased with decreasing diameter in vessels below 50 µm in diameter, contrary to the observations. Distributing sources/sinks along arterioles/venules led to velocities consistent with the data. CONCLUSIONS: These results imply that connections to the capillary plexus distributed along the arterioles and venules strongly affect the hemodynamic characteristics of the CAM. The theoretical model provides a basis for quantitative simulations of structural adaptation in CAM networks in response to hemodynamic stimuli.

Structure and hemodynamics of vascular networks in the chorioallantoic membrane of the chicken.

The chick chorioallantoic membrane (CAM) is extensively used as an in vivo model. Here, structure and hemodynamics of CAM vessel trees were analyzed and compared with predictions of Murray's law. CAM microvascular networks of Hamburger-Hamilton stage 40 chick embryos were scanned by videomicroscopy. Three networks with ∼3,800, 580, and 480 segments were digitally reconstructed, neglecting the capillary mesh. Vessel diameters (D) and segment lengths were measured, and generation numbers and junctional exponents at bifurcations were derived. In selected vessels, flow velocities (v) and hematocrit were measured. Hemodynamic simulations, incorporating the branching of capillaries from preterminal vessels, were used to estimate v, volume flow, shear stress (τ), and pressure for all segments of the largest network. For individual arteriovenous flow pathways, terminal arterial and venous generation numbers are negatively correlated, leading to low variability of total topological and morphological pathway lengths. Arteriolar velocity is proportional to diameter (v∝D1.03 measured, v∝D0.93 modeling), giving nearly uniform τ levels (τ∝D0.05). Venular trees exhibit slightly higher exponents (v∝D1.3, τ∝D0.38). Junctional exponents at divergent and convergent bifurcations were 2.05 ± 1.13 and 1.97 ± 0.95 (mean ± SD) in contrast to the value 3 predicted by Murray's law. In accordance with Murray's law, τ levels are (nearly) maintained in CAM arterial (venular) trees, suggesting vascular adaptation to shear stress. Arterial and venous trees show an interdigitating arrangement providing homogeneous flow pathway properties and have preterminal capillary branches. These properties may facilitate efficient oxygen exchange in the CAM during rapid embryonic growth.