ELOVL6 promotes the progression of head and neck squamous cell carcinoma via activating WNT/ß-catenin pathway.

This study was to explore the role of ELOVL6 in the development of head and neck squamous cell carcinoma (HNSCC). Considering its previously identified oncogenic role in hepatocellular carcinoma. ELOVL6 gene expression, clinicopathological analysis, enrichment analysis, and immune infiltration analysis were based on the data from Gene Expression Omnibus and The Cancer Genome Atlas, with additional bioinformatics analyses performed. Human HNSCC tissue microarray and cell lines were used. The expression of ELOVL6 in HNSCC was detected by quantitative polymerase chain reaction, immunohistochemistry assay, and western blot analysis. The proliferation ability of HNSCC cells, invasion, and apoptosis were evaluated using cell counting kit-8 method, Transwell assay, and flow cytometry, respectively. Based on the data derived from the cancer databases and our HNSCC cell and tissue studies, we found that ELOVL6 was overexpressed in HNSCC. Moreover, ELOVL6 expression level had a positive correlation with clinicopathology of HNSCC. Gene set enrichment analysis showed that ELOVL6 affected the occurrence of HNSCC through WNT signaling pathway. Functional experiments demonstrated that ELOVL6 knockdown inhibited the proliferation and invasion of HNSCC cells while promoting apoptosis. Additionally, compound 3f, an agonist of WNT/ß-catenin signaling pathway, enhances the effect of ELOVL6 on the progression of HNSCC cells. ELOVL6 is upregulated in HNSCC and promotes the development of HNSCC cells by inducing WNT/ß-catenin signaling pathway. ELOVL6 stands a potential target for the treatment of HNSCC and a prognosis indicator of human HNSCC.

Water-circulating probes significantly modify lesion length and axon damage in cooled radiofrequency ablations when compared with similar-sized standard radiofrequency probes in rats.

INTRODUCTION: Preclinical research demonstrated water-cooled radiofrequency (CRF) ablations have a significant impact on structural and functional changes compared to standard radiofrequency (SRF) ablations. Clinical procedures utilizing RF to treat chronic pain conditions also show sustained functional outcomes. We hypothesize that the design of the RF probes plays an important role in interventional procedure success, but it remains unclear which specific design features. METHODS: RF ablations were performed in male Lewis rats (n=51) using multiple-sized probes for CRF (17 Ga/2 mm and 17Ga/4 mm) and SRF (22Ga/5 mm, 18Ga/10 mm and 16Ga/10 mm) to evaluate generator energy output, lesion length, axon damage by histology and nerve function analysis via electromyography. To exclude probe design variables beyond size and remain objective, we tested cooled probes with and without water circulation, which resulted in the CRF probe performing like an SRF probe. RESULTS: Consistent with our previous findings in smaller probes, CRF large probes delivered more energy (p<0.01) and generated multiple zones of thermal damage in sciatic nerves. When the water-circulating feature was turned off, however, energy output (p<0.001) and lesion length (p<0.05) was significantly reduced. CRF probes with the water circulation also featured significantly more axonal disruption, than larger sized SRF probes (p<0.0001). CONCLUSIONS: Overall, this data confirms that CRF's water-circulating technology has a greater impact on energy deposition, lesion length and axon damage compared with SRF ablations. Moreover, results suggest that the structural differences between RF modalities cannot be solely attributed to probe size, and it may shed light on its differences in clinical outcomes.

Surgical management and the prognosis of iatrogenic facial nerve injury in middle ear surgery: a 20-year experience.

BACKGROUND: Iatrogenic facial nerve injury is one of the severest complications of middle ear surgery, this study aims to evaluate surgical management and prognosis in the era of improved surgical instruments. METHODS: Patients suffered from facial nerve paralysis after middle ear surgery between January 2000 and December 2019 were retrospectively collected. Demographic characters, primary disease and surgery, details of revision surgery were analyzed. RESULTS: Forty-five patients were collected, of whom 8 were injured at our center and 37 were transferred. For 8 patients injured at our center, seven (87.5%) ranked House-Brackmann (H-B) grade V and one (12.5%) ranked H-B VI before revision surgery; postoperatively, two (25.0%) patients recovered to H-B grade I, four (50.0%) recovered to H-B II, and the other two (25.0%) recovered to H-B III. For 37 patients transferred, thirteen (35.1%) ranked H-B grade V and 24 (64.9%) ranked H-B VI preoperatively, final postoperative grade ranked from H-B grade I to grade V, with H-B I 6 (16.2%) cases, H-B II 6 (16.2%) cases, H-B III 18 (48.6%) cases, H-B IV 5 (13.5%) cases and H-B V 2 (5.4%) cases. The most vulnerable site was tympanic segment (5, 62.5% and 27, 73.0% respectively). Twenty-one (46.7%) patients suffered from mild injury and 24 (53.3%) suffered from partial or complete nerve transection. For surgical management, twenty-one (46.7%) patients received decompression, nineteen (42.2%) received graft and 5 (11.1%) received anastomosis. Those decompressed within 2 months after paralysis had higher possibility of H-B grade I or II recovery (P = 0.026), those received graft within 6 months were more likely to get H-B grade III recovery (P = 0.041), and for patients underwent anastomosis within 6 months, all recovered to H-B grade III. CONCLUSIONS: Tympanic segment is the vulnerable site. If facial nerve paralysis happens, high-resolution computed tomography could help identify the injured site. Timely treatment is important, decompression within 2 months after paralysis, graft and anastomosis within 6 months lead to better recovery.

Dynamic Trajectory of a Patient-Reported Outcome and Its Associated Factors for Patients with Chronic Heart Failure: A Growth Mixture Model Approach.

Purpose: This study aimed to identify subgroups of chronic heart failure (CHF) patients with distinct trajectories of quality of life (QOL) and to identify baseline characteristics associated with the trajectories. Patients and methods: Two-year, prospective, cohort study including 315 patients with CHF was conducted from July 2017. Information on QOL assessed by CHF-patient-reported outcomes measure (CHF-PROM) was collected at baseline, 6, 12, 18, and 24 months. Demographic and clinical variables were recorded at baseline. Growth mixture model was used to identify distinct trajectories of CHF-PROM and its physical, psychological, social, and therapeutic domains. Single factor analysis was employed to assess the factors associated with development of CHF-PROM over time. Results: Two classes of overall score of CHF-PROM were identified: poorer (14.0%) and better (86.0%). Poorer class tended to be aged, have low diastolic blood pressure, have concomitant atrial fibrillation, diabetes, chronic obstructive pulmonary disease, cancers, and central nervous system diseases, and used nitrates. Three classes of physical scores were identified: unstable-poorer (5.2%), stable-poorer (29.4%) and better (65.4%). Age, NYHA grade, chronic obstructive pulmonary disease, combined with cancers and central nervous system diseases were related to the grouping. Poorer (8.6%) and better (91.4%) classes of psychological scores were identified. Poorer class tended to be female and had concomitant atrial fibrillation. Degenerate class (34.6%) and meliorate class (65.4%) of therapeutic scores were identified. Degenerate class tended to have concomitant chronic obstructive pulmonary disease and use less angiotensin converting enzyme inhibitors. Conclusion: We identified different classes with distinct trajectories of QOL that may help proper evaluate QOL and further improve its status for patients CHF.

Efficient synthesis of primary and secondary amides via reacting esters with alkali metal amidoboranes.

Amides are one of the most important organic compounds that are widely applied in medicine, biochemistry, and materials science. To find an efficient synthetic method of amides is a challenge for organic chemistry. We report here a facile synthesis method of primary and secondary amides through a direct amidation of esters with sodium amidoboranes (NaNHRBH3, R = H, Me), at room temperature without using catalysts and other reagents. This process is rapid and chemoselective, and features quantitative conversion and wide applicability for esters tolerating different functional groups. The experimental and theoretical studies reveal a reaction mechanism with nucleophilic addition followed by a swift proton transfer-induced elimination reaction.

A nomogram based on a patient-reported outcomes measure: predicting the risk of readmission for patients with chronic heart failure.

BACKGROUND: Health-related quality of life, as evaluated by a patient-reported outcomes measure (PROM), is an important prognostic marker in patients with chronic heart failure. This study aimed to use PROM to establish an effective readmission nomogram for chronic heart failure. METHODS: Using a PROM as a measurement tool, we conducted a readmission nomogram for chronic heart failure on a prospective observational study comprising of 454 patients with chronic heart failure hospitalized between May 2017 to January 2020. A Concordance index and calibration curve were used to evaluate the discriminative ability and predictive accuracy of the nomogram. A bootstrap resampling method was used for internal validation of results. RESULTS: The median follow-up period in the study was 372 days. After a final COX regression analysis, the gender, income, health care, appetite-sleep, anxiety, depression, paranoia, support, and independence were identified and included in the nomogram. The nomogram showed moderate discrimination, with a concordance index of 0.737 (95% CI 0.673-0.800). The calibration curves for the probability of readmission for patients with chronic heart failure showed high consistency between the probability, as predicted, and the actual probability. CONCLUSIONS: This model offers a platform to assess the risk of readmission for different populations with CHF and can assist clinicians with personalized treatment recommendations.

Cu(II)/Mn(III)-Promoted Synergistic Radical N-Heteroannulation Reaction: Synthesis of [60]Fullerene-Fused Tetrahydroquinoline Derivatives.

Cu(II)/Mn(III)-mediated synergistic radical N-heteroannulation reaction of [60]fullerene with N-sulfonylated o-amino-arylmalonates has been developed for the direct and efficient construction of [60]fullerene-fused tetrahydroquinoline derivatives. A plausible mechanism for the formation of fullerotetrahydroquinolines is proposed, and the electrochemical properties of the obtained fullerene adducts are investigated.

Controllable Synthesis and Catalytic Performance of Nanocrystals of Rare-Earth-Polyoxometalates.

Large-scale isolation of nanocrystals of rare-earth-polyoxometalates (RE-POMs) catalysts is important in fundamental research and applications. Here, we synthesized a family of monomeric RE-POMs by the self-assembly of Ta/W mixed-addendum POM {P2W15Ta3O62} and rare-earth (RE) ions. These RE-POMs with molecular formulas of [RE(H2O)7]3P2W15Ta3O62· nH2O (RE = Y, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) are all electroneutral molecular clusters, insoluble in water and common organic solvents. The electronic structures, electrochemical properties, and catalytic activities of them have been investigated by experimental and computational methods. In particular, based on a mild and controllable synthetic process, a convenient and controllable approach to prepare nanocrystals and self-organized aggregates of these monomers has been developed. They exhibit remarkable heterogeneous catalytic activity for cyanosilylation. Both the increased Lewis acid strength of RE in the title compounds, as indicated by theoretical calculations, and the decreased particle size contribute to their high catalytic performances.

[Effects of deoxygedunin on Alzheimer-like pathologic dysfunction induced by D-galactose combined with AlCl3].

OBJECTIVE: To investigate the effects of Deoxygedunin on Aß deposition, learning memory, and oxidative stress induced by D-galactose combined with AlCl3 in model rats with Alzheimer's disease and its possible mechanism. METHODS: Male SD rats were randomly divided into three groups (n=12):control group, model group (AD) and intervention group (AD+Deo). Morris water maze test was used to detect learning/memory and cognitive function in rats.Glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and malondialdehyde (MDA) contents in homogenate of hippocampus were detected by enzyme-linked immunosorbent assay (ELISA).Tau protein expression in rat cerebral cortex was detected by immunohistochemistry.Western blot was used to detect the expressions of extracellular signal regulated kinase 1(ERK1), protein kinase B (PKB) and tropomyosin-related kinase B (TrkB) on TrkB signaling pathway. RESULTS: The results of water maze test showed that D-galactose combined with AlCl3 induced a significant increase in the escape latency compared with the control group (P<0.05).Deoxygedunin could reverse the increase of the escape latency of the model group (P<0.05).On the 7th day after removal of the platform, the model group showed an increase in escape latency compared with the control group and the intervention group (P<0.01), and the number of crossing platforms was declined (P<0.05); The results of immunohistochemistry and ELISA showed that the expressions of Aß and tau protein in the model group were increased significantly compared with those of the control group (P<0.01).The activities of SOD and GSH-Px were decreased significantly and the content of MDA was increased significantly.Compared with the model group, Deoxygedunin could reverse the increase of the expressions of Aß and tau protein (P<0.01), the decrease of SOD and GSH-Px activities (P<0.05) and the increase of the MDA content (P<0.05).Western blot results showed that Deoxygedunin treatment reversed the decreased phosphorylation levels of TrkB, AKT and ERK1 in hippocampus of the model group. CONCLUSIONS: Supplement of Deoxygedunin can significantly reverse Aß deposition, oxidative stress and cognitive deficits by activating the TrkB signal transduction pathway, which suggest that Deoxygedunin may serve as a promising therapeutic candidate for attenuating AD-like pathological dysfunction induced by D-galactose combined with AlCl3.

Matrix metalloproteinase-2 and -9 contribute to functional integrity and noise­induced damage to the blood-labyrinth-barrier.

The cochlear blood-labyrinth barrier (BLB), located in the stria vascularis, is critical for the homeostasis of cochlear solutes and ion transport. Significant disruption to the BLB occurs early during noise­induced hearing loss. Matrix metalloproteinase (MMP)­2 and ­9 are important molecules known to be capable of degrading tight junction (TJ) proteins. The TJ proteins are important components of the extracellular matrix (ECM), required to maintain BLB integrity and permeability. Previous studies have demonstrated that MMP­2 and ­9, rich in healthy cochlea, serve an essential role in regulating the cochlear response to acoustic trauma. The present study investigated the localization and function of MMP­2 and ­9 in the BLB by determining their associated gene expression and activity under normal conditions and after noise exposure. Analysis of gene expression by RNA­sequencing (RNA­seq) revealed expression of 15 MMP­associated genes, including genes for MMP­2 and ­9, in healthy stria vascularis. Expression of these MMP genes was dynamically regulated by noise trauma to the cochlea, and accompanied by alterations in tissue inhibitors of metalloproteinases (TIMPs) and the TJ protein zona­occludens 1 (ZO­1). These alterations suggested that MMP­2 and ­9 serve an important role in maintaining the integrity of BLB and in response to acoustic trauma. MMP­2, MMP­9 and ZO­1 protein expression levels in the stria vascularis by immunofluorescence, and observed that the stable expression of MMP-2 and ­9 in healthy stria was markedly increased following noise exposure, consistent with the RNA­seq results. The compact structure of ZO­1 in the BLB loosened, and strial capillaries exhibited markedly increased leakage of Evans blue dye following acoustic trauma. These data indicated that mediation of MMP­2 and ­9 in structural damage to TJ proteins, including ZO­1, may be an important mechanism in the breakdown of the BLB following acoustic trauma. Additionally, these results indicated that MMPs are involved in regulating the integrity and permeability of the BLB, which may provide a theoretical basis for the prevention of noise­induced hearing loss.

Lanthanide derivatives of Ta/W mixed-addendum POMs as proton-conducting materials.

Four lanthanide derivatives of Ta-containing POMs [Ln3(H2O)22][P2W15Ta3O62]·nH2O (Ln = La, 1; Ce, 2; Pr, 3; and Nd, 4) were isolated by the self-assembly of Wells-Dawson type Ta/W mixed-addendum POM and lanthanide ions. Compound 1 showed excellent proton conduction performance at high relative humidities (RHs), with conductivity reaching 1.26 × 10-2 S cm-1 at 95 °C under 98% RH.

Expansion and angiogenic potential of mesenchymal stem cells from patients with critical limb ischemia.

BACKGROUND: Critical limb ischemia (CLI) is a life- and limb-threatening condition affecting 1% to 10% of the population with peripheral arterial disease. Traditional revascularization options are not possible for up to 50% of CLI patients, in which case, the use of cellular therapies, such as bone marrow-derived mesenchymal stem cells (MSCs), hold great promise as an alternative revascularization therapy. However, no randomized, controlled phase 3 trials to date have demonstrated an improvement in limb salvage with cellular therapies. This may be due to poor cell quality (ie, inability to generate a sufficient number of angiogenic MSCs) or to the inadequate retention and viability of MSCs after delivery, or both. Because concerns remain about the expansion and angiogenic potential of autologous MSCs in the CLI population, the objective of this study was to examine the effect of our novel culture media supplement, pooled human platelet lysate (PL), in lieu of the standard fetal bovine serum (FBS), to improve the expansion potential of MSCs from CLI patients. We also characterized the in vitro angiogenic activity of MSCs from the tibia of amputated CLI limbs compared with MSCs from healthy donors. METHODS: MSCs were obtained from the tibia of four CLI patients (ISC) and four ISC patients with diabetes mellitus (ISC+DM) undergoing major amputation. Healthy MSCs were aspirated from the iliac crest of four young and healthy donors. MSCs were isolated and expanded in culture with PL or FBS. MSCs from passage 3 to 6 were used for phenotypic marker expression and for adipogenic and osteogenic differentiation and were tested for their in vitro angiogenic activity on human microdermal endothelial cells. In parallel MSCs were cultured to passage 11 for population-doubling calculations. RESULTS: MSCs from ISC and ISC+DM patients and from healthy patients exhibited appropriate expression of cell surface markers and differentiation capacity. Population doublings were significantly greater for PL-stimulated compared with FBS-stimulated MSCs in all groups. Biologically active amounts of angiogens were identified in the secretome of all MSCs without consistent trends among groups. PL expansion did not adversely affect the angiogenic activity of MSCs compared with FBS. The ISC and ISC+DM MSCs demonstrated angiogenic effects on endothelial cells similar to those of healthy and ISC MSCs. CONCLUSIONS: PL promotes the rapid expansion of MSCs from CLI and healthy persons. Importantly, MSCs expanded from CLI patients demonstrate the desired angiogenic activity compared with their healthy counterparts. We conclude that autologous MSCs from CLI patients can be sufficiently expanded with PL and be expected to deliver requisite angiogenic effects in vivo. We expect the improved expansion of ISC and ISC+DM with PL to be helpful in improving the successful delivery of autologous MSCs to patients with CLI.

A Novel Approach to Assess the In Situ Versus Ex Vivo Mechanical Behaviors of the Coronary Artery.

Ex vivo mechanical testing has provided tremendous insight toward prediction of the in vivo mechanical behavior and local mechanical environment of the arterial wall; however, the role of perivascular support on the local mechanical behavior of arteries is not well understood. Here, we present a novel approach for quantifying the impact of the perivascular support on arterial mechanics using intravascular ultrasound (IVUS) on cadaveric porcine hearts. We performed pressure-diameter tests (n = 5) on the left anterior descending coronary arteries (LADCAs) in situ while embedded in their native perivascular environment using IVUS imaging and after removal of the perivascular support of the artery. We then performed standard cylindrical biaxial testing on these vessels ex vivo and compared the results. Removal of the perivascular support resulted in an upward shift of the pressure-diameter curve. Ex vivo testing, however, showed significantly lower circumferential compliance compared to the in situ configuration. On a second set of arteries, local axial stretch ratios were quantified (n = 5) along the length of the arteries. The average in situ axial stretch ratio was 1.28 ± 0.16; however, local axial stretch ratios showed significant variability, ranging from 1.01 to 1.70. Taken together, the data suggest that both the perivascular loading and the axial tethering have an important role in arterial mechanics. Combining nondestructive testing using IVUS with traditional ex vivo cylindrical biaxial testing yields a more comprehensive assessment of the mechanical behavior of arteries.

Residual deformations in ocular tissues.

Residual deformations strongly influence the local biomechanical environment in a number of connective tissues. The sclera is known to be biomechanically important in healthy and diseased eyes, such as in glaucoma. Here, we study the residual deformations of the sclera, as well as the adjacent choroid and retina. Using freshly harvested porcine eyes, we developed two approaches of quantifying residual deformations in the spherically shaped tissues of interest. The first consisted of punching discs from the posterior wall of the eye and quantifying the changes in the area and eccentricity of these samples. The second consisted of cutting a ring from the equatorial sclera and making stress-relieving cuts in it. Measurements of curvature were made before and after the stress-relieving cuts. Using the first approach, we observed a 42% areal contraction of the choroid, but only modest contractions of the sclera and retina. The observed contractions were asymmetric. In the second approach, we observed an opening of the scleral rings (approx. 10% decrease in curvature). We conclude that residual bending deformations are present in the sclera, which we speculate may be due to radially heterogeneous growth and remodelling of the tissue during normal development. Further, residual areal deformations present in the choroid may be due to the network of elastic fibres in this tissue and residual deformations in the constituent vascular bed. Future studies of ocular biomechanics should attempt to include effects of these residual deformations into mechanical models in order to gain a better understanding of the biomechanics of the ocular wall.

Residual shear deformations in the coronary artery.

Quantifying arterial residual deformations is critical for understanding the stresses and strains within the arterial wall during physiological and pathophysiological conditions. This study presents novel findings on residual shear deformations in the left anterior descending coronary artery. Residual shear deformations are most evident when thin, long axial strips are cut from the artery. These strips deform into helical configurations when placed in isotonic solution. A residual shear angle is introduced as a parameter to quantify the residual shear deformations. Furthermore, a stress analysis is performed to study the effects of residual shear deformations on the intramural shear stress distribution of an artery subjected to pressure, axial stretch, and torsion using numerical simulation. The results from the stress analyses suggest that residual shear deformations can significantly modulate the intramural shear stress across the arterial wall.

Differential mechanical response and microstructural organization between non-human primate femoral and carotid arteries.

Unique anatomic locations and physiologic functions predispose different arteries to varying mechanical responses and pathologies. However, the underlying causes of these mechanical differences are not well understood. The objective of this study was to first identify structural differences in the arterial matrix that would account for the mechanical differences between healthy femoral and carotid arteries and second to utilize these structural observations to perform a microstructurally motivated constitutive analysis. Femoral and carotid arteries were subjected to cylindrical biaxial loading and their microstructure was quantified using two-photon microscopy. The femoral arteries were found to be less compliant than the carotid arteries at physiologic loads, consistent with previous studies, despite similar extracellular compositions of collagen and elastin ([Formula: see text]). The femoral arteries exhibited significantly less circumferential dispersion of collagen fibers ([Formula: see text]), despite a similar mean fiber alignment direction as the carotid arteries. Elastin transmural distribution, in vivo axial stretch, and opening angles were also found to be distinctly different between the arteries. Lastly, we modeled the arteries' mechanical behaviors using a microstructural-based, distributed collagen fiber constitutive model. With this approach, the material parameters of the model were solved using the experimental microstructural observations. The findings of this study support an important role for microstructural organization in arterial stiffness.

In-situ characterization of the uncrimping process of arterial collagen fibers using two-photon confocal microscopy and digital image correlation.

Uncrimping of collagen fibers in the arterial wall is an integral process in regulating the macro-level mechanical response of arteries. Uncrimping of collagen fibers leads to a gradual, but significant strain-stiffening response of the artery at physiological pressures and prevents overdistention at elevated pressures. In this study, we imaged adventitial collagen fibers from fresh primate arteries using two-photon excitation microscopy while subjecting the arteries to physiological inflation pressures and axial stretches. The imaging focal plane was fixed at a constant radial location in the adventitial wall by adjusting the focal distance as the arteries inflated, allowing for the continuously monitoring of the uncrimping process of a single region of collagen fibers. Digital image correlation was then applied to the sequential images to assess and correlate the local displacements to manual traces of selected reference fibers and their engagements. We found that the collagen fibers of interest became fully engaged at a luminal pressure of 20mmHg, this was then followed by rotation of these fibers as the bulk artery continued to dilate. This technique helps to further the understanding of the uncrimping process of collagen fibers under physiological loads, which can aid in the development of more accurate microstructural constitutive models.

Remodeling of extracellular matrix patch used for carotid artery repair.

BACKGROUND: We evaluated the in vitro strength and in vivo arterial-wall response to an extracellular-matrix-based patch material in a sheep model of carotid artery repair. MATERIALS AND METHODS: A six-ply sheet of acellular, porcine extracellular matrix (ECM) was subjected to in vitro material strength testing and implanted in 15 sheep for 30, 90, and 180 d. Bovine pericardium was used as a control in some animals. In vivo graft patency was assessed by angiography. Explanted grafts were evaluated by histopathology and burst-strength testing. RESULTS: Mean (SD) in vitro suture retention force of the ECM sheet was 14.5 (3.06) N; tensile strength was 29.7 (6.11) N; and probe burst strength was 185 (22.6) N. In vivo, mild stenosis was observed at 30 d for all patches; stenosis was absent at 90 d in the ECM-repaired arteries but not bovine pericardium controls. Pseudoaneurysm was not observed in any animal. Histopathology showed progressive graft degradation, collagen deposition, formation of neocapillaries and fibrocellular neointima, and endothelialization, but no calcification. Mean (SD) burst pressure for unrepaired arteries was 2608 (858) mmHg and 1473 (694) mmHg for ECM-repaired vessels. Mean change in diameter from unloaded state to burst pressure was 29% (9.7) for unrepaired vessels and 24% (13.4) for ECM-repaired vessels. CONCLUSIONS: The six-ply ECM sheet can withstand the forces encountered after carotid artery repair. In sheep, it shows evidence of progressive, constructive remodeling as early as 30 d post-implantation with rapid deposition of endothelium. ECM shows promise as a patch material for CEA repair.

A mechanical analysis of conduit arteries accounting for longitudinal residual strains.

Identification of an appropriate stress-free reference configuration is critically important in providing a reasonable prediction of the intramural stress distribution when performing biomechanical analyses on arteries. The stress-free state is commonly approximated as a radially cut ring that typically opens into a nearly circular sector, relieving much of the circumferential residual strains that exist in the traction-free configuration. An opening angle is often used to characterize this sector. In this study, we first present experimental results showing significant residual deformations in the longitudinal direction of two commonly studied arteries in the pig: the common carotid artery and the left anterior descending coronary artery. We concluded that a radially cut ring cannot completely describe the stress-free state of the arteries. Instead, we propose the use of a longitudinal opening angle, in conjunction with the traditional circumferential opening angle, to experimentally quantify the stress-free state of an artery. Secondly, we propose a new kinematic model to account for the addition of longitudinal residual strains through employing the longitudinal opening angle and performed a stress analysis. We found that with the inclusion of longitudinal residual strains in the stress analysis, the predicted circumferential stress gradient was decreased by 3-fold and the predicted longitudinal stress gradient was increased by 5.7-fold. Thus, inclusion of longitudinal residual strains has a significant effect on the predicted stress distribution in arteries.