Tradeoff between storage capacity and embolism resistance in the xylem of temperate broadleaf tree species

2020 ◽  
Vol 40 (8) ◽  
pp. 1029-1042 ◽  
Author(s):  
Zhicheng Chen ◽  
Shidan Zhu ◽  
Yongtao Zhang ◽  
Junwei Luan ◽  
Shan Li ◽  
...  
Keyword(s):  
Water Transport ◽  
Wall Thickness ◽  
Vessel Wall ◽  
Storage Capacity ◽  
Mechanical Support ◽  
Hydraulic Efficiency ◽  
Axial Parenchyma ◽  
Fiber Wall ◽  
Embolism Resistance ◽  
Broadleaf Species

Abstract Xylem traits are critical plant functional traits associated with water transport, mechanical support, and carbohydrate and water storage. Studies on the xylem hydraulic efficiency–safety tradeoff are numerous; however, the storage function of xylem parenchyma is rarely considered. The effects of a substantial number of xylem traits on water transport, embolism resistance, mechanical support, storage capacity and nonstructural carbohydrate (NSC) content were investigated in 19 temperate broadleaf species planted in an arid limestone habitat in northern China. There was no xylem hydraulic efficiency–safety tradeoff in the 19 broadleaf species. The total parenchyma fraction was negatively correlated with the fiber fraction. Embolism resistance was positively correlated with indicators of xylem mechanical strength such as vessel wall reinforcement, vessel wall thickness and fiber wall thickness, and was negatively related to the axial parenchyma fraction, especially the paratracheal parenchyma fraction. The paratracheal parenchyma fraction was positively correlated with the ratio of the paratracheal parenchyma fraction to the vessel fraction. In addition, the xylem NSC concentration was positively related to the total parenchyma fraction and axial parenchyma fraction. There was a storage capacity–embolism resistance tradeoff in the xylem of 19 broadleaf species in arid limestone habitats. We speculate that the temperate broadleaf species may show a spectrum of xylem hydraulic strategies, from the embolism resistance strategy related to a more negative P50 (the water potential corresponding to 50% loss of xylem conductivity) to the embolization repair strategy based on more paratracheal parenchyma.

scholarly journals Complex wall modeling for hemodynamic simulations of intracranial aneurysms based on histologic images

2021 ◽  
Vol 16 (4) ◽  
pp. 597-607
Author(s):  
Annika Niemann ◽  
Samuel Voß ◽  
Riikka Tulamo ◽  
Simon Weigand ◽  
Bernhard Preim ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Vessel Wall ◽  
Intracranial Aneurysms ◽  
Geometric Model ◽  
Image Data ◽  
Outer Wall ◽  
3D Models ◽  
Patient Specific ◽  
Intracranial Vessel ◽  
Hemodynamic Simulations

Abstract Purpose For the evaluation and rupture risk assessment of intracranial aneurysms, clinical, morphological and hemodynamic parameters are analyzed. The reliability of intracranial hemodynamic simulations strongly depends on the underlying models. Due to the missing information about the intracranial vessel wall, the patient-specific wall thickness is often neglected as well as the specific physiological and pathological properties of the vessel wall. Methods In this work, we present a model for structural simulations with patient-specific wall thickness including different tissue types based on postmortem histologic image data. Images of histologic 2D slices from intracranial aneurysms were manually segmented in nine tissue classes. After virtual inflation, they were combined into 3D models. This approach yields multiple 3D models of the inner and outer wall and different tissue parts as a prerequisite for subsequent simulations. Result We presented a pipeline to generate 3D models of aneurysms with respect to the different tissue textures occurring in the wall. First experiments show that including the variance of the tissue in the structural simulation affect the simulation result. Especially at the interfaces between neighboring tissue classes, the larger influence of stiffer components on the stability equilibrium became obvious. Conclusion The presented approach enables the creation of a geometric model with differentiated wall tissue. This information can be used for different applications, like hemodynamic simulations, to increase the modeling accuracy.

scholarly journals Comparison of alternate preparative techniques on wall thickness in coronary artery bypass grafts: the HArVeST randomised controlled trial

2021 ◽  
Author(s):  
Gianni Angelini ◽  
Tom Johnson ◽  
Culliford Lucy ◽  
Gavin Murphy ◽  
Tracy Harris ◽  
...  
Keyword(s):  
High Pressure ◽  
Coronary Artery ◽  
Wall Thickness ◽  
Vessel Wall ◽  
Controlled Trial ◽  
Artery Bypass ◽  
Low Pressure ◽  
Wall Thickening ◽  
Pressure Testing ◽  
Randomised Controlled

Background: The success of coronary artery bypass grafting surgery (CABG) is dependent on long-term graft patency, which is negatively related to early wall thickening. Avoiding high-pressure distension testing for leaks and preserving the surrounding pedicle of fat and adventitia during vein harvesting may reduce wall thickening. Methods: A single-centre, factorial randomised controlled trial was carried out to compare the impact of testing for leaks under high versus low pressure and harvesting the vein with versus without the pedicle in patients undergoing CABG. The primary outcomes were graft wall thickness, as indicator of medial-intimal hyperplasia, and lumen diameter assessed using intravascular ultrasound after 12 months. Results: 96 eligible participants were recruited. With conventional harvest, low-pressure testing tended to yield a thinner vessel wall compared to high-pressure (mean difference MD (low minus high) -0.059mm, 95%CI -0.12, +0.0039, p=0.066). With high pressure testing, veins harvested with the pedicle fat tended to have a thinner vessel wall than those harvested conventionally (MD (pedicle minus conventional) -0.057mm, 95%CI -0.12, +0.0037, p=0.066, test for interaction p=0.07). Lumen diameter was similar across groups (harvest comparison p=0.81; pressure comparison p=0.24). Low pressure testing was associated with fewer hospital admissions in the 12 months following surgery (p=0.0008). Harvesting the vein with the pedicle fat was associated with more complications during the index admission (p=0.0041). Conclusions: Conventional saphenous vein graft preparation with low pressure distension and harvesting the vein with a surrounding pedicle yielded similar graft wall thickness after 12 months, but low pressure was associated with fewer adverse events.

scholarly journals A neutralizing IL-11 antibody reduces vessel hyperplasia in a mouse carotid artery wire injury model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
David Schumacher ◽  
Elisa A. Liehn ◽  
Pakhwan Nilcham ◽  
David Castaño Mayan ◽  
Chutima Rattanasopa ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Wall Thickness ◽  
Vessel Wall ◽  
Neointimal Hyperplasia ◽  
Endothelial Injury ◽  
Collagen Content ◽  
Arterial Stenosis ◽  
Matrix Metalloproteinase 2 ◽  
Vessel Wall Thickness ◽  
Artery Disease

AbstractVascular restenosis remains a major problem in patients with coronary artery disease (CAD) and peripheral artery disease (PAD). Neointimal hyperplasia, defined by post-procedure proliferation and migration of vascular smooth muscle cells (VSMCs) is a key underlying pathology. Here we investigated the role of Interleukin 11 (IL-11) in a mouse model of injury-related plaque development. Apoe−/− mice were fed a hyperlipidaemic diet and subjected to carotid wire injury of the right carotid. Mice were injected with an anti-IL11 antibody (X203), IgG control antibody or buffer. We performed ultrasound analysis to assess vessel wall thickness and blood velocity. Using histology and immunofluorescence approaches, we determined the effects of IL-11 inhibition on VSMC and macrophages phenotypes and fibrosis. Treatment of mice with carotid wire injury using X203 significantly reduced post-endothelial injury vessel wall thickness, and injury-related plaque, when compared to control. Immunofluorescence staining of the injury-related plaque showed that X203 treatment did not reduce macrophage numbers, but reduced the number of VSMCs and lowered matrix metalloproteinase 2 (MMP2) levels and collagen content in comparison to control. X203 treatment was associated with a significant increase in smooth muscle protein 22α (SM22α) positive cells in injury-related plaque compared to control, suggesting preservation of the contractile VSMC phenotype. Interestingly, X203 also reduced the collagen content of uninjured carotid arteries as compared to IgG, showing an additional effect on hyperlipidemia-induced arterial remodeling in the absence of mechanical injury. Therapeutic inhibition of IL-11 reduced vessel wall thickness, attenuated neointimal hyperplasia, and has favorable effects on vascular remodeling following wire-induced endothelial injury. This suggests IL-11 inhibition as a potential novel therapeutic approach to reduce arterial stenosis following revascularization in CAD and PAD patients.

New model for predicting tensile strength and density of eucalyptus handsheets based on an activation parameter calculated from fiber distribution characteristics

Holzforschung ◽  
2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Iiro Pulkkinen ◽  
Juha Fiskari ◽  
Ville Alopaeus
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Wall Thickness ◽  
Water Retention ◽  
Activation Parameter ◽  
Water Retention Value ◽  
Data Set ◽  
Network Activation ◽  
Fiber Wall ◽  
Fiber Segment

Abstract The activation parameter developed is based on the fiber wall thickness distribution, fiber curl distribution, and water retention value of the unrefined fibers. The mechanical properties of paper that contain chemical pulp depend, among other things, on the free fiber segment activation between fiber-fiber crossings that is created during drying. Experimental data revealed that the degree of fiber swelling is responsible together with the fiber shape factor (curl) and fiber wall thickness for the extent of fiber network activation. The amount of bonding between fibers also affects fiber segment activation. Based on the experimental data, it was deduced that interfiber bonding ability of fibers, characterized as the water retention value, was mainly responsible for the development of handsheet density. Tensile index development was more affected by the morphology of fibers, which was the main determinant for high activation potential of fibers. Factor analysis was used to identify the main causes of variation for a refining data set of 20 Eucalyptus grandis samples. Three independent descriptors were found to be responsible for the majority of the variation: the bonding and activation factor, the factor of microcompressions, and the factor of fiber wall thickness and fiber curl. The activation parameter developed in this study can be used to determine the effect of fiber segment activation and inter-fiber bonding on the inplane mechanical properties of paper.

Structural organization in palm stems of Roystonea regia and Archontophoenix alexandrae

IAWA Journal ◽  
2020 ◽  
pp. 1-26
Author(s):  
Amy Ny Aina Aritsara ◽  
Kun-Fang Cao
Keyword(s):  
Water Transport ◽  
Structural Organization ◽  
Spatial Organization ◽  
Mechanical Support ◽  
Trade Off ◽  
Breast Height ◽  
Mechanical Constraints ◽  
Fiber Fraction ◽  
Trade Offs ◽  
Palm Species

Abstract Having a high stature subjects palms to the same constraints as trees, but the lack of cambial growth urges them to adopt a different strategy. We aimed to characterize the spatial organization of xylem tissues and their potential functions in two palm stems: a 30 cm diameter at breast height (DBH) royal palm (Roystonea regia) and a 12 cm DBH Alexandra king palm (Archontophoenix alexandrae). Macroscopic and microscopic anatomical characteristics were assessed at five vertical locations and 5–6 radial locations at each height. Over 9600 vessels across the two stems were drawn manually and measured based on histological sections. Vertically, a hydraulic bottleneck was identified at the first meter, and both stems showed conduit tapering from 4 m to the top. Radially, most water transport and mechanical support were achieved within 2–5 cm below the bark. The larger stem diameter of royal palm may have improved its water transport, storage, and potential for mechanical support compared to king palm. There was a strong trade-off between ground parenchyma and the fiber fraction. However, the correlation between theoretical hydraulic conductivity (Kt) and the ground parenchyma fraction, and between Kt and the fiber fraction, shifted from positive or non-significant below the bark, to strongly negative close to the center. These changes reflect the functional sectoriality of the palm stems, which may reduce the constraint of trade-offs between water transport, storage, and mechanical support. To conclude, functional sectoriality may have helped both palm species to withstand the hydraulic and mechanical constraints due to high stature.

Atherosclerosis: Carotid vessel wall thickness and aortic stiffness compared to stenosis class in peripheral arterial disease

2013 ◽  
Vol 24 ◽  
pp. e38-e39
Author(s):  
Harrie CM van den Bosch ◽  
Jos JM Westenberg ◽  
Wikke Setz-Pels ◽  
Alette Daniels-Gooszen ◽  
Lucien EM Duijm ◽  
...  
Keyword(s):  
Peripheral Arterial Disease ◽  
Wall Thickness ◽  
Vessel Wall ◽  
Aortic Stiffness ◽  
Arterial Disease ◽  
Vessel Wall Thickness ◽  
Carotid Vessel Wall ◽  
Peripheral Arterial ◽  
Carotid Vessel

Towards Non-Invasive Pressure Assessment

2010 ◽  
Author(s):  
Nathalie Bijnens ◽  
Bart Beulen ◽  
Peter Brands ◽  
Marcel Rutten ◽  
Frans van de Vosse
Keyword(s):  
Wall Thickness ◽  
Vessel Wall ◽  
Biomechanical Properties ◽  
Vessel Diameter ◽  
Local Pressure ◽  
Vessel Wall Thickness ◽  
Non Invasive ◽  
Vascular Impedance ◽  
Vessel Wall Properties ◽  
Invasive Techniques

In clinical practice, ultrasound is frequently applied to non-invasively assess blood velocity, blood volume flow and blood vessel wall properties such as vessel wall thickness and vessel diameter waveforms. To convert these properties into relevant biomechanical properties that are related to cardiovascular disease (CVD), such as elastic modulus and compliance of the vessel wall, local pressure has to be assessed simultaneously with vessel wall thickness and vessel diameter waveforms. Additionally, accurate estimates of vascular impedance (transfer function between pressure and blood flow) can be a valuable tool for the estimation of the condition of the vessel, e.g., to diagnose stenosis. Studies of arterial impedance in humans, however, are hampered by the lack of reliable non-invasive techniques to simultaneously record pressure and flow locally as a function of time. Local pressure assessment together with flow has great potential for improving the ability to diagnose and monitor CVD.

Human Carotid Atherosclerotic Plaque Growth Function and Progression Simulation Using Meshless GFD and Statistical Methods Based on Multi-Year In Vivo MRI

2008 ◽  
Author(s):  
Chun Yang ◽  
Joseph D. Petruccelli ◽  
Zhongzhao Teng ◽  
Chun Yuan ◽  
Gador Canton ◽  
...  
Keyword(s):  
Atherosclerotic Plaque ◽  
Wall Thickness ◽  
Vessel Wall ◽  
Plaque Rupture ◽  
Patient Specific ◽  
Tracking Data ◽  
Plaque Progression ◽  
Vessel Wall Thickness ◽  
Plaque Growth

Atherosclerotic plaque rupture and progression have been the focus of intensive investigations in recent years. The mechanisms governing plaque progression and rupture process are not well understood. Using computational models based on patient-specific multi-year in vivo MRI data, our recent results indicated that 18 out of 21 patients studied showed significant negative correlation between plaque progression measured by vessel wall thickness increase (WTI) and plaque wall (structural) stress (PWS) [1]. In this paper, a computational procedure based on meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to simulate plaque progression. Participating patients were scanned three times (T1, T2, and T3, at intervals of approximately 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes were used as the measure for plaque progression. Starting from T2 plaque geometry, plaque progression was simulated by solving the solid model and adjusting wall thickness using plaque growth functions iteratively until time T3 is reached. Numerically simulated plaque progression showed very good agreement with actual plaque geometry at T3 given by MRI data. We believe this is the first time plaque progression simulation results based on multi-year patient-tracking data are reported. Multi-year tracking data and MRI-based progression simulation add time dimension to plaque vulnerability assessment and will improve prediction accuracy.

scholarly journals Increased Coronary Vessel Wall Thickness in HIV-Infected Young Adults

2014 ◽  
Vol 59 (12) ◽  
pp. 1779-1786 ◽  
Author(s):  
K. Z. Abd-Elmoniem ◽  
A. B. Unsal ◽  
S. Eshera ◽  
J. R. Matta ◽  
N. Muldoon ◽  
...  
Keyword(s):  
Young Adults ◽  
Wall Thickness ◽  
Vessel Wall ◽  
Coronary Vessel ◽  
Coronary Vessel Wall ◽  
Vessel Wall Thickness

scholarly journals Pore constrictions in intervessel pit membranes reduce the risk of embolism spreading in angiosperm xylem

2020 ◽  
Author(s):  
Lucian Kaack ◽  
Matthias Weber ◽  
Emilie Isasa ◽  
Zohreh Karimi ◽  
Shan Li ◽  
...  
Keyword(s):  
Strong Relationship ◽  
Mechanistic Explanation ◽  
Membrane Thickness ◽  
List Type ◽  
Hydraulic Efficiency ◽  
Pit Membrane ◽  
Hydraulic Safety ◽  
Embolism Resistance

SummaryEmbolism spreading in angiosperm xylem occurs via mesoporous pit membranes between vessels. Here, we investigate how the size of pore constrictions in pit membranes is related to pit membrane thickness and embolism resistance.In three models, pit membranes are modelled as multiple layers to investigate how pit membrane thickness and the number of intervessel pits per vessel determine pore constriction sizes, the probability of encountering large pores, and air-seeding. These estimations were complemented by measurements of pit membrane thickness, embolism resistance, and number of intervessel pits per vessel (n = 31, 31, and 20 species, respectively).Constriction sizes in pores decreased with increasing pit membrane thickness, which agreed with the measured relationship between pit membrane thickness and embolism resistance. The number of pits per vessel affected constriction size and embolism resistance much less than pit membrane thickness. A strong relationship between estimated air-seeding pressures and measured embolism resistance was observed.Pore constrictions provide a mechanistic explanation why pit membrane thickness determines embolism resistance, and suggest that hydraulic safety can be uncoupled from hydraulic efficiency. Although embolism spreading remains puzzling and encompasses more than pore constriction sizes, angiosperms are unlikely to have leaky pit membranes, which enables tensile transport of water.

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