Biomedical subjects

E Vanbavel

Publications and source records attributed to E Vanbavel.

4 recordsLinked to original sources

PubMed2007

Relation between branching patterns and perfusion in stochastic generated coronary arterial trees.

Biological variation in branching patterns is likely to affect perfusion of tissue. To assess the fundamental consequences of branching characteristics, 50 stochastic asymmetrical coronary trees and one non-stochastic symmetrical branching tree were generated. In the stochastic trees, area growth, A, at branching points was varied: A = random; 1.00; 1.10; 1.13 and 1.15 and symmetry, S, was varied: S = random; 1.00; 0.70; 0.58; 0.50 and 0.48. With random S and A values, a large variation in flow and volume was found, linearly related to the number of vessels in the trees. Large A values resulted in high number of vessels and high flow and volume values, indicating vessels connected in parallel. Lowering symmetry values increased the number of vessels, however, without changing flow, indicating a dominant connection of vessels in series. Both large A and small S values gave more realistic gradual pressure drops compared to the symmetrical non-stochastic branching tree. This study showed large variations in tree realizations, which may reflect real biological variations in tree anatomies. Furthermore, perfusion of tissue clearly depends on the branching rules applied.

Arteries↗

PubMed2004

Morphological and functional alterations in glycerol preserved rat aortic allografts.

Glycerol preservation is an effective method for long-term preservation of skin allografts and has a potential use in preserving arterial allografts. We evaluated the effect of glycerol concentration and incubation period on vessel-wall integrity of rat aortic allografts. No significant differences were measured in breaking strength (2.3 +/- 0.3 N) and bursting pressure (223 +/- 32 kPa) between standard glycerolized and control segments (1.7 +/- 0.3 N, 226 +/- 17 kPa). Isometric tension measurements showed complete lack of functional contraction and relaxation capacity in allograft segments prepared according to all preservation protocols. Morphologically, thickness of the vessel-wall media diminished after preservation using low (30/50/75%) or high (70/85/98%) concentrations of glycerol, as compared to control segments (i.e. 81 +/- 2.4 microm, 95 +/- 5.6 microm and 125 +/- 3.5 microm, respectively). Confocal microscopy and Fourier analysis demonstrated that vascular collagen and elastin bundle orientation had remained unaltered. Electron microscopy showed defragmentation of luminal endothelial cells. In conclusion, glycerol preservation of rat aorta resulted in an acellular tissue matrix, which maintained biomechanical integrity and extracellular matrix characteristics. The next step in the investigation will be to test the concept of glycerol preservation of arterial allografts in a vascular transplantation model.

Animals↗

PubMed2001

Impact of current cryopreservation procedures on mechanical and functional properties of human aortic homografts.

We evaluated the impact f standard cryopreservation on mechanical and functional properties of human aortic homografts. From 14 human heart-valve donors, the thoracic descending aorta was obtained. Effects of cryopreservation on mechanical (elastic properties and breaking stress) and smooth muscle cell (SMC) and endothelium function were tested. Cryopreservation (cryo) did not significantly affect Young's modulus of elastin (fresh: 3.1 +/- 1.0, cryo: 2.7 +/- 0.9 x 10(5) Nm(-2)), collagen recruitment pressure (fresh: 1.1 +/- 0.3, cryo: 1.1 +/- 0.4 x 10(4) Nm(-2)), distensibility (fresh: 3.8 +/- 1.8, cryo: 3.6 +/- 1.6 x 10(5) N(-1)m2), or breaking stress (fresh: 2.4 +/- 1.0, cryo: 2.2 +/- 1.0 x 10(6) Nm(-2)). Following explantation, no endothelium-dependent relaxation was found. SMC function and endothelium-independent relaxation were mainly intact after explantation but significantly decreased after cryopreservation. Aortic mechanical properties are not influenced by cryopreservation. Following explantation, almost no endothelial cell function is present, and SMC contractility is strongly affected after cryopreservation.

Adolescent↗

PubMed1999

The influence of aging and aortic stiffness on permanent dilation and breaking stress of the thoracic descending aorta.

OBJECTIVE: To assess the influence of aging and aortic stiffness on the extent of irreversible deformation and breaking stress of the human thoracic aorta. METHODS: From 14 human heart valve donors without aortic disease (mean age 35 years, range 8-59 years), 14 intact segments of the thoracic descending aorta were studied within 48 h after cardiac arrest. In an experimental setup, the segments were submitted to increasing hydrostatic pressure loads, both statically and dynamically, while radius and wall thickness were monitored echocardiographically. Pressure-radius curves were constructed. Radius and wall thickness were determined at a pressure of 100 mmHg. Radius at elastin resting length and collagen recruitment pressure (Pcol, mmHg) were derived from the pressure-radius relationship and stress-strain curves were constructed to yield Young's moduli of elastin and collagen. Distensibility (D, mmHg-1) was determined while loading the segment with a sinusoidal pressure wave of 120/50 mmHg at both 0.5 and 1 Hz. Subsequently increasing static pressure loads of 400, 800, 1200 and 1600 mmHg were applied. After each pressure load, the increase in aortic radius at a pressure of 100 mmHg (Rinc) was determined. The experiment continued until rupture occurred and breaking stress (sigma break, N m-2) was calculated, donor age and aortic stiffness were correlated with Rinc and sigma break of the aortic segments. RESULTS: Mean breaking stress of the 14 segments was 2.7 x 10(6) N m-2. Breaking stress was negatively correlated with age (r2 = 0.66) and positively with D (r2 = 0.44) and with Pcol (r2 = 0.18). Seven segments survived a pressure load of 800 mmHg, in these vessels, the extent of irreversible dilation was positively correlated with age (r2 = 0.42) and negatively with D (r2 = 0.40) and Pcol (r2 = 0.40). CONCLUSION: Permanent deformation and rupture of the human thoracic aorta following pressure overload are influenced by age, distensibility and collagen recruitment pressure.

Adolescent↗