Vascular Morphology Research Articles

In Vivo Assessment of Deep Vascular Patterns in Murine Colitis Using Optoacoustic Mesoscopic Imaging.

The analysis of vascular morphology and functionality enables the assessment of disease activity and therapeutic effects in various pathologies. Raster-scanning optoacoustic mesoscopy (RSOM) is an imaging modality that enables the visualization of superficial vascular networks in vivo. In murine models of colitis, deep vascular networks in the colon wall can be visualized by transrectal absorber guide raster-scanning optoacoustic mesoscopy (TAG-RSOM). In order to accelerate the implementation of this technology in translational studies of inflammatory bowel disease, an image-processing pipeline for TAG-RSOM data has been developed. Using optoacoustic data from a murine model of chemically-induced colitis, different image segmentation methods are compared for visualization and quantification of deep vascular patterns in terms of vascular network length and complexity, blood volume, and vessel diameter. The presented image-processing pipeline for TAG-RSOM enables label-free in vivo assessment of changes in the vascular network in murine colitis with broad applications for inflammatory bowel disease research.

μCT imaging of a multi-organ vascular fingerprint in rats.

The importance of microvascular imaging in diagnosis and therapeutic targeting of various diseases is increasingly recognized. The new approach emphasizes the need for holistic studies to understand the inter-organ vascular cross-talk. Here, we report on the development of a novel perfusion protocol which consistently delivers a micro-computed tomography contrast agent to micro-vessels of multiple organs in a single experimental animal. We describe the achieved repeatability of the perfusions, as well as the image analysis steps developed individually for each organ type. We also optimize image acquisition by investigating the compromise between shortening of the scanning time and preservation of the highest possible spatial resolution. Taking together, with the multi-organ perfusion, optimized image acquisition, and the conceived image analysis steps, we provide a comprehensive and reliable experimental protocol for studying vascular morphology and pathology in multi-organ diseases.

Depth-Dependent Contributions of Various Vascular Zones to Cerebral Autoregulation and Functional Hyperemia: An In-Silico Analysis.

Autoregulation and neurogliavascular coupling are key mechanisms that modulate myogenic tone (MT) in vessels to regulate cerebral blood flow (CBF) during resting state and periods of increased neural activity, respectively. To determine relative contributions of distinct vascular zones across different cortical depths in CBF regulation, we developed a simplified yet detailed and computationally efficient model of the mouse cerebrovasculature. The model integrates multiple simplifications and generalizations regarding vascular morphology, the hierarchical organization of mural cells, and potentiation/inhibition of MT in vessels. Our analysis showed that autoregulation is the result of the synergy between these factors, but achieving an optimal balance across all cortical depths and throughout the autoregulation range is a complex task. This complexity explains the non-uniformity observed experimentally in capillary blood flow at different cortical depths. In silico simulations of cerebral autoregulation support the idea that the cerebral vasculature does not maintain a plateau of blood flow throughout the autoregulatory range and consists of both flat and sloped phases. We learned that small-diameter vessels with large contractility, such as penetrating arterioles and precapillary arterioles, have major control over intravascular pressure at the entry points of capillaries and play a significant role in CBF regulation. However, temporal alterations in capillary diameter contribute moderately to cerebral autoregulation and minimally to functional hyperemia. In addition, hemodynamic analysis shows that while hemodynamics within capillaries remain relatively stable across all cortical depths throughout the entire autoregulation range, significant variability in hemodynamics can be observed within the first few branch orders of precapillary arterioles or transitional zone vessels. The computationally efficient cerebrovasculature model, proposed in this study, provides a novel framework for analyzing dynamics of the CBF regulation where hemodynamic and vasodynamic interactions are the foundation on which more sophisticated models can be developed.

Comparative Study on Vascular Bundle Morphological Characteristics of Parts of Branches, Culms, and Rhizomes of Oligostachyum sulcatum

This study presents a comprehensive analysis of the vascular bundle morphology, tangential and radial diameters, and distribution frequency of different parts of Oligostachyum sulcatum, elucidating their structural and functional significance. Electron microscopy images revealed distinct vascular bundle characteristics in the different parts, including the vascular bundles in both parts of the rhizomes, the middle parts of the internodes, and the middle and inner parts of the branches, which were semi-open. The vascular bundles in the outer parts of both internodes and branches were semi-differentiated and undifferentiated. The vascular bundles in the inner parts of internodes were open. Statistical analysis showed significant variations in tangential and radial diameters among these parts, reflecting their diverse mechanical and physiological functions. The internodes exhibited the largest tangential and radial diameters, suggesting a critical role in mechanical support. In contrast, the branches had the smallest diameter, indicating that vascular bundle differentiation is influenced by growth conditions. The vascular bundle frequency was the highest in branches and the lowest in inside-sticks. This study provides theoretical references for the adaptive strategies and growth regulation mechanisms of O. sulcatum.

Enhanced lymphangiogenesis in the left lateral segment of a biopsied liver during portoenterostomy for biliary atresia

PurposeWe investigate the histopathology of the portal vein branches and lymphatic vessels to elucidate the mechanism of atrophy of the left lateral segment (LLS) of the liver in biliary atresia (BA).MethodsLLS and right anterior segment (RAS) liver biopsy samples obtained during Kasai portoenterostomy (KPE) from ten consecutive patients with BA underwent histopathological investigation of the portal vein and lymphatic vessels using double chromogenic immunostaining for CD31/D2-40 and the hepatitis-like findings (HLF) score. Each parameter and clinical data were compared between prognostic groups.ResultsHLF scores in the LLS were always higher than those in the RAS. There was no difference in portal vein and lymphatic vascular morphology, whereas the number of lymphatic vessels was correlated with the fibrotic area of all specimen areas. Left-to-right ratio of the number of lymphatic vessels was correlated with the age at KPE (r = 0.784, p = 0.007) and the pre-KPE CRP value (r = 0.723, p = 0.018).ConclusionsLymphangiogenesis on the LLS compared to the RAS was significantly correlated with the degree of fibrosis and the age at KPE. Further investigation is warranted to clarify the causes of LLS atrophy and lymphangiogenesis relevant to immune dysregulation.

Effects of Aerobic Exercise on Vascular Wall Thickness: A Meta-Analysis of Pre-Clinical Trials on Rat Model.

Exercise instigates adaptations in structural as well as functional organisation of the body at tissue and organ levels. However, the effect of exercise on vascular wall morphology is still under investigation. The objective of the review is to provide a meta-analysis of data from the previously published research to provide compiled analysis to determine the effect of exercise on the thickness of large-sized vessel walls. This meta-analysis was executed at the Ziauddin College of Rehabilitation Sciences with an extensive literature search using databases and search engines such as Pubmed, CINAHL, Web of Science, Scopus, and Google Scholar between September 2022 and January 2023. Studies were appraised according to an estimate of mean difference and pooled effect size was calculated using a random effect model. The risk of bias was also calculated using SYRCLE's risk of bias tool and CAMARADES. Overall, five eligible pre-clinical trials using rat models with pertinent data to determine the effect of exercise on vessel wall thickness were included in the meta-analysis. The results showed that aerobic exercise significantly reduced the vessel wall thickness (SMD -0.854 5%; CI: -1.365 to -0.344; p <0.001). Moreover, no significant publication bias was found through funnel plot and statistical test (Egger's p = 0.276; Begg's p = 0.624). However, an extensive review of the literature currently available on the topic has shown mixed findings that are consistent with the study and vice versa. Therefore, it indicated the need for sub-group analysis with different types of exercises for more peculiar clinical approaches. Key Words: Morphometry, Animal studies meta-analysis, Media thickness, Physical activity, Vascular morphology.

Enhancing mechanical properties of concrete with 3D printed vascular networks via carbonation strengthening

Vascular systems offer promising potential for enabling self-recovery in cementitious materials, but their construction in three dimensions presents significant challenges. Our group has developed an embedded printing strategy allowing for the freeform construction of 3D hollow vascular channels, overcoming previous limitations. However, concerns persist regarding the weakening of mechanical properties caused by these vascular channels. In this study, we utilize carbon dioxide curing to reinforce the vascular wall, mitigating the mechanical loss associated with hollow vascular channel. We investigate the effect of carbonation on the vascular channel wall's morphology, composition, and microhardness along the radial direction to gain insight into its impact. Additionally, we analyze the influence of both vascular channels and carbonated vascular channels on intensity and cracking behaviors under various loading directions. The findings from this investigation provide essential insights for the design and optimization of vascular networks in concrete structures.

Characterization of Banana Crowns: Microscopic Observations and Macroscopic Cutting Experiments

Banana crowns’ intricate vascular systems facilitate nutrient transport for fruit growth and provide mechanical support. Analyzing vascular bundle morphology facilitates understanding of its influence on the banana de-handing process. In this study, we employed X-ray Computed Tomography (CT) scanning and microscopic observation of paraffin sections to characterize the morphological traits of the banana crown’s vascular tissue system and reconstructed its 3D vascular tissue system throughout the banana bunch. Based on the internal tissue characteristics and external morphology, the banana crown is categorized into three regions: the central stalk–crown transition region (CSCTR), the crown expansion region (CER), and the crown–finger transition region (CFTR). Cutting experiments indicated that variations in the cutting strength and specific cutting energy across positions within the banana bunch were insignificant but significantly distinct among the three regions. Specifically, the CER showed a 19.7% reduction in cutting strength and a 15.5% decrease in energy consumption compared to the other regions. This was due to the unique cross-distribution of fibers within the CER, which were primarily parallel to the cutting blade, significantly reducing cutting forces and energy consumption, making the CER the optimal region for cutting. The orientation of vascular bundles relative to the blade is key to optimizing plant cutting mechanics.

AI-based fully automatic analysis of retinal vascular morphology in pediatric high myopia

PurposeTo investigate the changes in retinal vascular structures associated with various stages of myopia by designing automated software based on an artificial intelligence model.MethodsThe study involved 1324 pediatric participants from the National Children’s Medical Center in China, and 2366 high-quality retinal images and corresponding refractive parameters were obtained and analyzed. Spherical equivalent refraction (SER) degree was calculated. We proposed a data analysis model based on a combination of the Convolutional Neural Networks (CNN) model and the attention module to classify images, segment vascular structures, and measure vascular parameters, such as main angle (MA), branching angle (BA), bifurcation edge angle (BEA) and bifurcation edge coefficient (BEC). One-way ANOVA compared parameter measurements between the normal fundus, low myopia, moderate myopia, and high myopia groups.ResultsThe mean age was 9.85 ± 2.60 years, with an average SER of -1.49 ± 3.16D in the right eye and − 1.48 ± 3.13D in the left eye. There were 279 (12.38%) images in the normal group and 384 (16.23%) images in the high myopia group. Compared with normal fundus, the MA of fundus vessels in different myopic refractive groups was significantly reduced (P = 0.006, P = 0.004, P = 0.019, respectively), and the performance of the venous system was particularly obvious (P < 0.001). At the same time, the BEC decreased disproportionately (P < 0.001). Further analysis of fundus vascular parameters at different degrees of myopia showed that there were also significant differences in BA and branching coefficient (BC). The arterial BA value of the fundus vessel in the high myopia group was lower than that of other groups (P = 0.032, 95% confidence interval [CI], 0.22–4.86), while the venous BA values increased (P = 0.026). The BEC values of high myopia were higher than those of low and moderate myopia groups. When the loss function of our data classification model converged to 0.09, the model accuracy reached 94.19%.ConclusionThe progression of myopia is associated with a series of quantitative retinal vascular parameters, particularly the vascular angles. As the degree of myopia increases, the diversity of vascular characteristics represented by these parameters also increases.

Photoplethysmography-Based Angiography of Skin Tumors in Arbitrary Areas of Human Body.

Noninvasive, rapid, and robust diagnostic techniques for clinical screening of tumors located in arbitrary areas of the human body are in demand. To address this challenge, we analyzed the feasibility of photoplethysmography-based angiography for assessing vascular structures within malignant and benign tumors. The proposed hardware and software were approved in a clinical study involving 30 patients with tumors located in the legs, torso, arms, and head. High-contrast and detailed vessel maps within both benign and malignant tumors were obtained. We demonstrated that capillary maps are consistent and can be interpreted using well-established dermoscopic criteria for vascular morphology. Vessel mapping provides valuable details, which may not be available in dermoscopic images and can aid in determining whether a tumor is benign or malignant. We believe that the proposed approach may become a valuable tool in the preliminary cancer diagnosis and is suitable for large-scale screening.

Periconceptional maternal intake of ultra-processed foods, energy and macronutrients the impact on imaging markers of early utero-placental vascular development: The rotterdam periconception cohort

Background & AimsThe quantity and quality of maternal nutrition in the periconception period is an important determinant for embryonic and foetal development and subsequent pregnancy course and outcome. The intake of ultra-processed foods (UPF) has increased worldwide and adverse health outcomes have been reported. However, the impact of UPF intake on the placenta, essential for prenatal nourishment, is unknown. Therefore, we aim to investigate associations between the periconceptional maternal intake of UPF, energy and related macronutrients, and first-trimester utero-placental vascular development. MethodsWe included 214 ongoing pregnancies in the Virtual Placenta study, a subcohort of the Rotterdam periconception cohort. At enrollment, participants filled out a food frequency questionnaire from which we calculated the average daily energy from UPF, total energy intake and macronutrient intake from UPF. At 7-9-11 weeks of gestation, we performed sequential three-dimensional power Doppler ultrasounds of the first-trimester utero-placental vasculature. Virtual Organ Computer-aided AnaLysis (VOCAL) software, Virtual Reality segmentation and a skeletonization algorithm were applied to measure placental volume (PV), utero-placental vascular volume (uPVV) and generate the utero-placental vascular skeleton (uPVS). Absolute vascular morphology was quantified by assigning a morphologic characteristic to each voxel in the uPVS (end-, bifurcation-, crossing- or vessel point) and used to calculate density of vascular branching. Linear mixed models adjusted for confounders were used to investigate associations between maternal intake of UPF, total energy and macronutrients from UPF and PV, uPVV and uPVS characteristics ResultsEnergy intake from UPF and total energy intake were not consistently associated with imaging markers of utero-placental vascular development. . Higher carbohydrate intake of 10g/day from UPF was associated with increased uPVS trajectories (end points (β=0.34, 95%CI=0.07;0.61), bifurcation points (β=0.38, 95%CI=0.05;0.70), vessel points (β=0.957, 95%CI=0.21;1.71). No associations were observed with PV. ConclusionsAgainst our hypothesis, periconceptional maternal intake of UPF and total energy were not convincingly associated with impaired first-trimester utero-placental vascular development. Remarkably, the increased intake of carbohydrates from UPF, which is often considered ‘unhealthy’, is positively associated with first-trimester utero-placental vascular development. Given the complexity of diet, further research should elucidate what underlies these findings to be able to interpret how nutrition may impact utero-placental vascular development in early pregnancy. Clinical trial numberThis study is registered at the Dutch Trial Register (NTR6854).

Perspective or Spectacle? Teaching thoracic aortic anatomy in a mixed reality assisted educational approach– a two-armed randomized pilot study

PurposeAnatomical understanding is an important basis for medical teaching, especially in a surgical context. The interpretation of complex vascular structures via two-dimensional visualization can yet be difficult, particularly for students. The objective of this study was to investigate the feasibility of an MxR-assisted educational approach in vascular surgery undergraduate education, comparing an MxR-based teaching-intervention with CT-based material for learning and understanding the vascular morphology of the thoracic aorta.MethodsIn a prospective randomized controlled trial learning success and diagnostic skills following an MxR- vs. a CT-based intervention was investigated in 120 thoracic aortic visualizations. Secondary outcomes were motivation, system-usability as well as workload/satisfaction. Motivational factors and training-experience were also assessed. Twelve students (7 females; mean age: 23 years) were randomized into two groups undergoing educational intervention with MxR or CT.ResultsEvaluation of learning success showed a mean improvement of 1.17 points (max.score: 10; 95%CI: 0.36–1.97). The MxR-group has improved by a mean of 1.33 [95% CI: 0.16–2.51], against 1.0 points [95% CI: -0.71- 2.71] in the CT-group. Regarding diagnostic skills, both groups performed equally (CT-group: 58.25 ± 7.86 vs. MxR-group:58.5 ± 6.60; max. score 92.0). 11/12 participants were convinced that MxR facilitated learning of vascular morphologies. The usability of the MxR-system was rated positively, and the perceived workload was low.ConclusionMxR-systems can be a valuable addition to vascular surgery education. Further evaluation of the technology in larger teaching situations are required. Especially regarding the acquisition of practical skills, the use of MxR-systems offers interesting application possibilities in surgical education.

Exploring Morphometry of Endometrial Glands and Blood Vessels in Reproductive Age Women With Abnormal Uterine Bleeding.

Background Abnormal uterine bleeding (AUB) is one of the most common problems encountered in gynaecological practice. Defective endometrial angiogenesis has been implicated in various benign and malignant disorders of the endometrium. Aim This study aims to assess morphometry of endometrial glands and blood vessels in patients with AUB. Material and methods This is a one year retrospective cross sectional analysis of endometrial samples received with the diagnosis of AUB in reproductive age group. All samples were routinely processed and stained. Sections were analysed for morphometry of blood vessels and endometrial glands. Results A total of 374 cases were included. Most common histological group was proliferative followed by secretory phase. A significant difference was noted in mean vascular density, diameter, mitotic scores and height of glandular epithelium in different benign and malignant groups. Conclusion This study highlights the fact that glandular and vascular morphometry can be used to differentiate between various proliferative disorders of the endometrium. In the current era of new anti-angiogenic therapies, endometrial angiogenesis and changes in vascular morphology can be targeted, thus improving treatment modalities and patient care.

Vascular endothelial cell morphology and alignment regulate VEGF-induced endothelial nitric oxide synthase activation.

Nitric oxide (NO) production by endothelial nitric oxide synthase (eNOS) inhibits platelet and leukocyte adhesion while promoting vasorelaxation in smooth muscle cells. Dysfunctional regulation of eNOS is a hallmark of various vascular pathologies, notably atherosclerosis, often associated with areas of low shear stress on endothelial cells (ECs). While the link between EC morphology and local hemodynamics is acknowledged, the specific impact of EC morphology on eNOS regulation remains unclear. Morphological differences between elongated, aligned ECs and polygonal, randomly oriented ECs correspond to variations in focal adhesion and cytoskeletal organization, suggesting differing levels of cytoskeletal prestress. However, the functional outcomes of cytoskeletal prestress, particularly in the absence of shear stress, are not extensively studied in ECs. Some evidence suggests that elongated ECs exhibit decreased immunogenicity and enhanced NO production. This study aims to elucidate the signaling pathways governing VEGF-stimulated eNOS regulation in the aligned EC phenotype characterized by elongated and aligned cells within a monolayer. Using anisotropic topographic cues, bovine aortic endothelial cells (BAECs) were elongated and aligned, followed by VEGF treatment in the presence or absence of cytoskeletal tension inhibitors. Phosphorylation of eNOS ser1179, AKT ser437 and FAK Tyr397 in response to VEGF challenge were significantly heightened in aligned ECs compared to unaligned ECs. Moreover this response proved to be robustly tied to cytoskeletal tension as evinced by the abrogation of responses in the presence of the myosin II ATPase inhibitor, blebbistatin. Notably, this work demonstrates for the first time the reliance on FAK phosphorylation in VEGF-mediated eNOS activation and the comparatively greater contribution of the cytoskeletal machinery in propagating VEGF-eNOS signaling in aligned and elongated ECs. This research underscores the importance of utilizing appropriate vascular models in drug development and sheds light on potential mechanisms underlying vascular function and pathology that can help inform vascular graft design.

Reappraisal of tacrolimus levels after liver transplant for HCC: A multicenter study toward personalized immunosuppression regimen.

Post-liver transplant (LT) immunosuppression is necessary to prevent rejection; however, a major consequence of this is tumor recurrence. Although recurrence is a concern after LT for patients with HCC, the oncologically optimal tacrolimus (FK) regimen is still unknown. This retrospective study included 1406 patients with HCC who underwent LT (2002-2019) at 4 US institutions using variable post-LT immunosuppression regimens. Receiver operating characteristic analyses were performed to investigate the influences of post-LT time-weighted average FK (TWA-FK) level on HCC recurrence. A competing risk analysis was employed to evaluate the prognostic influence of TWA-FK while adjusting for patient and tumor characteristics. The AUC for TWA-FK was greatest at 2 weeks (0.68), followed by 1 week (0.64) after LT. Importantly, this was consistently observed across the institutions despite immunosuppression regimen variability. In addition, the TWA-FK at 2 weeks was not associated with rejection within 6 months of LT. A competing risk regression analysis showed that TWA-FK at 2 weeks after LT is significantly associated with recurrence (HR: 1.31, 95% CI: 1.21-1.41, p < 0.001). The TWA-FK effect on recurrence varied depending on the exposure level and the individual's risk of recurrence, including vascular invasion and tumor morphology. Although previous studies have explored the influence of FK levels at 1-3 months after LT on HCC recurrence, this current study suggests that earlier time points and exposure levels must be evaluated. Each patient's oncological risk must also be considered in developing an individualized immunosuppression regimen.

Hemodynamics in the treatment of pseudoaneurysm caused by extreme constriction of aortic arch with coated stent.

To evaluate the changes in distal vascular morphology and hemodynamics in patients with extremely severe aortic coarctation (CoA) after covered palliative (CP) stent dilation with different surgical strategies. Perioperative computed tomography angiography and digital subtraction angiography were utilized to construct three aortic models with varying stenosis rates and one follow-up model in a patient with extremely severe CoA. The models included: an idealized non-stenosed model (A: 0%), a model post initial stent deployment (B: 28%), a model post balloon expansion (C: 39%), and a model 18 months after post-balloon expansion (D: 39%). Consistent boundary conditions were applied to all models, and hemodynamic simulation was conducted using the pure fluid method. The narrowest and distal diameter of the stent increased by 34.71% and 59.29%, respectively, from model B to C. Additionally, the distal diameter of the stent increased by -13.80% and +43.68% compared to the descending aorta diameter, respectively. Furthermore, the ellipticity of the maximum cross-section of the aneurysm region in model A to D continued to increase. The oscillatory shear index at the stenosis to the region of the aneurysm were found to be higher in Models A and B, and lower in Models C and D. At the moment of maximum flow velocity, the blood flow distribution in models A and B was more uniform in the widest section of the blood vessels at the distal end of the stenosis, whereas models C and D exhibited disturbed blood flow with more than 2 eddy currents. The time-averaged wall shear stress (TAWSS) decreased in the distal and basal aneurysms, while it significantly increased at the step position. The aneurysmal region exhibited an endothelial cell activation potential value lower than 0.4 Pa-1. In patients with extremely severe CoA, it is crucial to ensure that the expanded diameter at both ends of the CP stent does not exceed the native vascular diameter during deployment. Our simulation results demonstrate that overdilation leads to a decrease in the TAWSS above the injured vessel, creating an abnormal hemodynamic environment that may contribute to the development and enlargement of false aneurysms in the early postoperative period. ClinicalTrials.gov, (NCT02917980).

Social deficits mirror delayed cerebrovascular dysfunction after traumatic brain injury

Traumatic brain injury (TBI) survivors face debilitating long-term psychosocial consequences, including social isolation and depression. TBI modifies neurovascular physiology and behavior but the chronic physiological implications of altered brain perfusion on social interactions are unknown. Adult C57/BL6 male mice received a moderate cortical TBI, and social behaviors were assessed at baseline, 3-, 7-, 14-, 30-, and 60-days post injury (dpi). Magnetic resonance imaging (MRI, 9.4T) using dynamic susceptibility contrast perfusion weighted MRI were acquired. At 60dpi mice underwent histological angioarchitectural mapping. Analysis utilized standardized protocols followed by cross-correlation metrics. Social behavior deficits at 60dpi emerged as reduced interactions with a familiar cage-mate (partner) that mirrored significant reductions in cerebral blood flow (CBF) at 60dpi. CBF perturbations were dynamic temporally and across brain regions including regions known to regulate social behavior such as hippocampus, hypothalamus, and rhinal cortex. Social isolation in TBI-mice emerged with a significant decline in preference to spend time with a cage mate. Cortical vascular density was also reduced corroborating the decline in brain perfusion and social interactions. Thus, the late emergence of social interaction deficits mirrored the reduced vascular density and CBF in regions known to be involved in social behaviors. Vascular morphology and function improved prior to the late decrements in social function and our correlations strongly implicate a linkage between vascular density, cerebral perfusion, and social interactions. Our study provides a clinically relevant timeline of alterations in social deficits alongside functional vascular recovery that can guide future therapeutics.

Rapamycin increases murine lifespan but does not reduce mineral volume in the Matrix GLA Protein (MGP) knockout mouse model of medial arterial calcification.

Peripheral artery disease (PAD) is the narrowing of the arteries that carry blood to the lower extremities. PAD has been traditionally associated with atherosclerosis. However, recent studies have found that medial arterial calcification (MAC) is the primary cause of chronic limb ischemia below the knee. MAC involves calcification of the elastin fibers surrounding smooth muscle cells (SMCs) in arteries. Matrix GLA Protein (MGP) binds circulating calcium and inhibits vascular calcification. Mgp -/- mice develop severe MAC and die within 8 weeks of birth due to aortic rupture or heart failure. We previously discovered a rare genetic disease Arterial Calcification due to Deficiency in CD73 (ACDC) in which patients present with extensive MAC in their lower extremity arteries. Using a patient-specific induced pluripotent stem cell model we found that rapamycin inhibited calcification. Here we investigated whether rapamycin could reduce MAC in vivo using Mgp -/- mice as a model. Mgp +/+ and Mgp -/- mice received 5mg/kg rapamycin or vehicle. Calcification content was assessed via microCT, and vascular morphology and extracellular matrix content assessed histologically. Immunostaining and western blot analysis were used to examine SMC phenotypes and cellular functions. Rapamycin prolonged Mgp -/- mice lifespan, decreased mineral density in the arteries, and increased smooth muscle actin protein levels, however, calcification volume, vessel morphology, SMC proliferation, and autophagy flux were all unchanged. These findings suggest that rapamycin's effects in the Mgp -/- mouse are independent of the vascular phenotype.

Machine Learning and Statistical Shape Modelling Methodologies to Assess Vascular Morphology before and after Aortic Valve Replacement.

Introduction: Statistical shape modelling (SSM) is used to analyse morphology, discover qualitatively and quantitatively unique shape features within a population, and generate mean shapes and shape modes that show morphological variability. Hierarchical agglomerative clustering is a machine learning analysis used to identify subgroups within a given population in relation to shape features. We tested the application of both methods in the clinically relevant scenario of patients undergoing aortic valve repair (AVR). Every year, around 5000 patients undergo surgical AVR in the UK. Aims: Evaluate aortic morphology and identify subgroups amongst patients who had undergone AVR, including Ozaki, Ross, and valve-sparing procedures using SSM and unsupervised hierarchical clustering analysis. This methodological framework can evaluate both pre- and post-surgical variability across subgroups undergoing different surgeries. Methods: Pre- (n = 47) and post- (n = 35) operative three-dimensional (3D) aortic models were reconstructed from computed tomography (CT) and cardiac magnetic resonance (CMR) images. Computational analyses for SSM and hierarchical clustering were run separately for the two subgroups, assessing (a) ascending aorta only and (b) the whole aorta. This allows for exploring possible variations in morphological classification related to the input shape. Results: Most patients in the Ross procedure subgroup exhibited differences in aortic morphology from other subgroups, including an elongated ascending and wide aortic arch pre-operatively, and an elongated ascending aorta with a slightly enlarged sinus post-operatively. In hierarchical clustering, the Ross aortas also appeared to cluster together compared to the other surgical procedures, both pre-operatively and post-operatively. There were significant differences between clusters in terms of clustering distance in the pre-operative analyses (p = 0.003 for ascending aortas, p = 0.016 for whole aortas). There were no significant differences between the clusters in post-operative analyses (p = 0.47 for ascending, p = 0.19 for whole aorta). Conclusions: We demonstrated the feasibility of evaluating aortic morphology before and after different aortic valve surgeries using SSM and hierarchical clustering. This framework could be used to further explore shape features associated with surgical decision-making pre-operatively and, importantly, to identify subgroups whose morphology is associated with poorer clinical outcomes post-operatively. Statistical shape modelling (SSM) and unsupervised hierarchical clustering are two statistical methods that can be used to assess morphology, show morphological variations, with the latter being able to identify subgroups within a population. These methods have been applied to the population of aortic valve replacement (AVR) patients since there are different surgical procedures (traditional AVR, Ozaki, Ross, and valve-sparing). The aim is to evaluate aortic morphology and identify subgroups within this population before and after surgery. Computed tomography and cardiac magnetic resonance images were reconstructed into 3D models of the ascending aorta and whole aorta, which were then input into SSM and hierarchical clustering. The results show that the Ross aortic morphology is quite different from the other aortas. The clustering did not classify the aortas based on the surgical procedures; however, most of the Ross group did cluster together, indicating low variability within this surgical group.

Histological Identification of Physiological Changes in Vascular Cell Morphology in the Lower Stem of Winter Barley (Hordeum vulgare L.) during Freezing

Histological Identification of Physiological Changes in Vascular Cell Morphology in the Lower Stem of Winter Barley (Hordeum vulgare L.) during Freezing