Sickle Cell Anemia Mediates Carotid Artery Expansive Remodeling That Can Be Prevented by Inhibition of JNK (c-Jun N-Terminal Kinase).

OBJECTIVE: Sickle cell anemia (SCA) causes chronic inflammation and multiorgan damage. Less understood are the arterial complications, most evident by increased strokes among children. Proteolytic mechanisms, biomechanical consequences, and pharmaceutical inhibitory strategies were studied in a mouse model to provide a platform for mechanistic and intervention studies of large artery damage due to sickle cell disease. Approach and Results: Townes humanized transgenic mouse model of SCA was used to test the hypothesis that elastic lamina and structural damage in carotid arteries increased with age and was accelerated in mice homozygous for SCA (sickle cell anemia homozygous genotype [SS]) due to inflammatory signaling pathways activating proteolytic enzymes. Elastic lamina fragmentation observed by 1 month in SS mice compared with heterozygous littermate controls (sickle cell trait heterozygous genotype [AS]). Positive immunostaining for cathepsin K, a powerful collagenase and elastase, confirmed accelerated proteolytic activity in SS carotids. Larger cross-sectional areas were quantified by magnetic resonance angiography and increased arterial compliance in SS carotids were also measured. Inhibiting JNK (c-jun N-terminal kinase) signaling with SP600125 significantly reduced cathepsin K expression, elastin fragmentation, and carotid artery perimeters in SS mice. By 5 months of age, continued medial thinning and collagen degradation was mitigated by treatment of SS mice with JNK inhibitor. CONCLUSIONS: Arterial remodeling due to SCA is mediated by JNK signaling, cathepsin proteolytic upregulation, and degradation of elastin and collagen. Demonstration in Townes mice establishes their utility for mechanistic studies of arterial vasculopathy, related complications, and therapeutic interventions for large artery damage due to SCA.

Effects of reverse deployment of cone-shaped vena cava filter on improvements in hemodynamic performance in vena cava.

BACKGROUND: Cone-shaped vena cava filters (VCFs) are widely used to treat venous thromboembolism. However, in the long term, the problem of occlusion persists even after the filter is deployed. A previous study hypothesized that the reverse deployment of a cone-shaped VCFs may prevent filter blockage. METHODS: To explore this hypothesis, a comparative study of the traditional and reverse deployments of VCFs was conducted using a computational fluid dynamics approach. The distribution of wall shear stress (WSS) and shear stress-related parameters were calculated to evaluate the differences in hemodynamic effects between both conditions. In the animal experiment, we reversely deployed a filter in the vena cava of a goat and analyzed the blood clot distribution in the filter. RESULTS: The numerical simulation showed that the reverse deployment of a VCF resulted in a slightly higher shear rate on the thrombus, and no reductions in the oscillating shear index (OSI) and relative residence time (RRT) on the vessel wall. Comparing the traditional method with the reversely deployed cases, the shear rate values is 16.49 and 16.48 1/s, respectively; the minimal OSI values are 0.01 and 0.04, respectively; in the vicinity of the VCF, the RRT values are both approximately 5 1/Pa; and the WSS is approximately 0.3 Pa for both cases. Therefore, the reverse deployment of cone-shaped filters is not advantageous when compared with the traditional method in terms of local hemodynamics. However, it is effective in capturing thrombi in the short term, as demonstrated via animal experiments. The reversely deployed cone-shaped filter captured the thrombi at its center in the experiments. CONCLUSIONS: Thus, the reverse deployment of cone-shaped filters is not advantageous when compared with the traditional method in terms of local hemodynamics. Therefore, we would not suggest the reverse deployment of the cone-shaped filter in the vena cava to prevent a potentially fatal pulmonary embolism.

Age-dependent characterization of carotid and cerebral artery geometries in a transgenic mouse model of sickle cell anemia using ultrasound and microcomputed tomography.

To define morphological changes in carotid and cerebral arteries in sickle cell transgenic mice (SS) as they age, a combination of ultrasound and microcomputed tomography of plastinated arteries was used to quantify arterial dimensions and changes in mice 4, 12, and 24 weeks of age. 12-week SS mice had significantly larger common carotid artery diameters than AS mice, which continued through to the extracranial and intracranial portions of the internal carotid artery (ICA). There were also side specific differences in diameters between the left and right vessels. Significant ICA tapering along its length occurred by 12- and 24-weeks in SS mice, decreasing by as much as 70%. Significant narrowing along the length was also measured in SS anterior cerebral arteries at 12- and 24-weeks, but not AS. Collectively, these findings indicate that sickle cell anemia induces arterial remodeling in 12- and 24-weeks old mice. Catalog of measurements are also provided for the common carotid, internal carotid, anterior cerebral, and middle cerebral arteries for AS and SS genotypes, as a reference for other investigators using mathematical and computational models of age-dependent arterial complications caused by sickle cell anemia.

Charge transport mechanisms in potassium superoxide.

Rechargeable metal-air batteries based on superoxide discharge products are attractive due to the facile one-electron redox process of O2/O2-. Recently, a K-O2 battery has been reported that showed a significantly lower discharge/charge potential gap than the Li-O2 battery systems. Here, we perform first-principles calculations on potassium superoxide (KO2) to unravel the charge transport mechanism in this discharge product. The concentration and mobility of intrinsic carriers are calculated. The results show that hole polarons and negatively charged potassium ion vacancies are the main charge carriers. The conductivity associated with polaron hopping (2 × 10-12 S cm-1) is 8 orders of magnitude higher than that of Li2O2, and the ionic conductivity has a comparable value (1 × 10-13 S cm-1). Our calculation results can rationalize the experimental findings and provide a theoretical basis for the understanding of superoxide discharge products in metal-air batteries.

Morphometric, Hemodynamic, and Multi-Omics Analyses in Heart Failure Rats with Preserved Ejection Fraction.

(1) Background: There are no successive treatments for heart failure with preserved ejection fraction (HFpEF) because of complex interactions between environmental, histological, and genetic risk factors. The objective of the study is to investigate changes in cardiomyocytes and molecular networks associated with HFpEF. (2) Methods: Dahl salt-sensitive (DSS) rats developed HFpEF when fed with a high-salt (HS) diet for 7 weeks, which was confirmed by in vivo and ex vivo measurements. Shotgun proteomics, microarray, Western blot, and quantitative RT-PCR analyses were further carried out to investigate cellular and molecular mechanisms. (3) Results: Rats with HFpEF showed diastolic dysfunction, impaired systolic function, and prolonged repolarization of myocytes, owing to an increase in cell size and apoptosis of myocytes. Heatmap of multi-omics further showed significant differences between rats with HFpEF and controls. Gene Set Enrichment Analysis (GSEA) of multi-omics revealed genetic risk factors involved in cardiac muscle contraction, proteasome, B cell receptor signaling, and p53 signaling pathway. Gene Ontology (GO) analysis of multi-omics showed the inflammatory response and mitochondrial fission as top biological processes that may deteriorate myocyte stiffening. GO analysis of protein-to-protein network indicated cytoskeleton protein, cell fraction, enzyme binding, and ATP binding as the top enriched molecular functions. Western blot validated upregulated Mff and Itga9 and downregulated Map1lc3a in the HS group, which likely contributed to accumulation of aberrant mitochondria to increase ROS and elevation of myocyte stiffness, and subsequent contractile dysfunction and myocardial apoptosis. (4) Conclusions: Multi-omics analysis revealed multiple pathways associated with HFpEF. This study shows insight into molecular mechanisms for the development of HFpEF and may provide potential targets for the treatment of HFpEF.

[Application of cardiac assist device and its biomechanics research for heart failure].

As an important means of treating heart failure (HF), cardiac assist device has been widely used in clinic. This paper reviews the application status, existing problems and future development trend of cardiac assist devices, including the classification of cardiac assist devices, representative research achievements and indications of the assist devices. It also summarizes the biomechanical indexes of the heart and the new approaches and methods for treating heart failure, as well as the hemodynamic studies of cardiac assist devices in recent years. The research findings provide references for further optimization of cardiac assist device structure and clinical application of the device.

Intraspecific scaling laws are preserved in ventricular hypertrophy but not in heart failure.

It is scientifically and clinically important to understand the structure-function scaling of coronary arterial trees in compensatory (e.g., left and right ventricular hypertrophy, LVH and RVH) and decompensatory vascular remodeling (e.g., congestive heart failure, CHF). This study hypothesizes that intraspecific scaling power laws of vascular trees are preserved in hypertrophic hearts but not in CHF swine hearts. To test the hypothesis, we carried out the scaling analysis based on morphometry and hemodynamics of coronary arterial trees in moderate LVH, severe RVH, and CHF compared with age-matched respective control hearts. The scaling exponents of volume-diameter, length-volume, and flow-diameter power laws in control hearts were consistent with the theoretical predictions (i.e., 3, 7/9, and 7/3, respectively), which remained unchanged in LVH and RVH hearts. The scaling exponents were also preserved with an increase of body weight during normal growth of control animals. In contrast, CHF increased the exponents of volume-diameter and flow-diameter scaling laws to 4.25 ± 1.50 and 3.15 ± 1.49, respectively, in the epicardial arterial trees. This study validates the predictive utility of the scaling laws to diagnose vascular structure and function in CHF hearts to identify the borderline between compensatory and decompensatory remodeling.

Morphometric and hemodynamic analysis of atherosclerotic progression in human carotid artery bifurcations.

Although atherosclerosis has been widely investigated at carotid artery bifurcation, there is a lack of morphometric and hemodynamic data at different stages of the disease. The purpose of this study was to determine the lesion difference in patients with carotid artery disease compared with healthy control subjects. The three-dimensional (3D) geometry of carotid artery bifurcation was reconstructed from computed tomography angiography (CTA) images of Chinese control subjects (n = 30) and patients with carotid artery disease (n = 30). We defined two novel vector angles (i.e., angles 1 and 2) that were tangential to the reconstructed contour of the 3D vessel. The best-fit diameter was computed along the internal carotid artery (ICA) center line. Hemodynamic analysis was performed at various bifurcations. Patients with stenotic vessels have larger angles 1 and 2 (151 ± 11° and 42 ± 20°) and smaller diameters of the external carotid artery (ECA) (4.6 ± 0.85 mm) compared with control subjects (144 ± 13° and 36 ± 16°, 5.2 ± 0.57 mm) although there is no significant difference in the common carotid artery (CCA) (7.1 ± 1.2 vs. 7.5 ± 1.0 mm, P = 0.18). In particular, all patients with carotid artery disease have a stenosis at the proximal ICA (including both sinus and carina regions), while 20% of patients have stenosis at the middle ICA and 20% have stenosis expansion to the entire cervical ICA. Morphometric and hemodynamic analyses suggest that atherosclerotic plaques initiate at both sinus and carina regions of ICA and progress downstream.

The effect of extracellular conductivity on electroporation-mediated molecular delivery.

In this work, the effect of extra-cellular conductivity on electroporation-mediated molecular delivery efficiency is investigated. A numerical model combining the Smoluchowski equation for membrane permeabilization and the Nernst-Planck equations for ion transport is used to simulate the evolution of ion concentration spatially and temporally. The results are compared with and used to interpret trends observed from previous experimental measurements. Agreements are found which suggest the critical importance of electrophoretic transport. This mechanism controls delivery efficiency on the quantitative level. Meanwhile, a simple formula is developed to predict the molecular content delivered via electrophoresis. The formula can be used as a compact model which provides good approximation to the full numerical model while avoiding the computational cost.

The alteration of the structure and macroscopic mechanical response of porcine patellar tendon by elastase digestion.

Background: The treatment of patellar tendon injury has always been an unsolved problem, and mechanical characterization is very important for its repair and reconstruction. Elastin is a contributor to mechanics, but it is not clear how it affects the elasticity, viscoelastic properties, and structure of patellar tendon. Methods: The patellar tendons from six fresh adult experimental pigs were used in this study and they were made into 77 samples. The patellar tendon was specifically degraded by elastase, and the regional mechanical response and structural changes were investigated by: (1) Based on the previous study of elastase treatment conditions, the biochemical quantification of collagen, glycosaminoglycan and total protein was carried out; (2) The patellar tendon was divided into the proximal, central, and distal regions, and then the axial tensile test and stress relaxation test were performed before and after phosphate-buffered saline (PBS) or elastase treatment; (3) The dynamic constitutive model was established by the obtained mechanical data; (4) The structural relationship between elastin and collagen fibers was analyzed by two-photon microscopy and histology. Results: There was no statistical difference in mechanics between patellar tendon regions. Compared with those before elastase treatment, the low tensile modulus decreased by 75%-80%, the high tensile modulus decreased by 38%-47%, and the transition strain was prolonged after treatment. For viscoelastic behavior, the stress relaxation increased, the initial slope increased by 55%, the saturation slope increased by 44%, and the transition time increased by 25% after enzyme treatment. Elastin degradation made the collagen fibers of patellar tendon become disordered and looser, and the fiber wavelength increased significantly. Conclusion: The results of this study show that elastin plays an important role in the mechanical properties and fiber structure stability of patellar tendon, which supplements the structure-function relationship information of patellar tendon. The established constitutive model is of great significance to the prediction, repair and replacement of patellar tendon injury. In addition, human patellar tendon has a higher elastin content, so the results of this study can provide supporting information on the natural properties of tendon elastin degradation and guide the development of artificial patellar tendon biomaterials.

A stochastic model for DNA translocation through an electropore.

A 1D Fokker-Planck simulation of DNA translocation through an electropore under finite pulses is presented. This study is motivated by applications relevant to DNA electrotransfer into biological cells via electroporation. The results review important insights. The translocation may occur on two disparate time scales, the electrophoretic time (~ms), and the diffusive time (~s), depending on the pulse length. Furthermore, a power-law correlation is observed, F-PST~(V(m)t(p))(a)/N(b), where F-PST is the final probability of successful translocation, V(m) is the transmembrane potential, t(p) is the pulse length, and N is the DNA length in segments. The values for a and b are close to 1 and 1.5, respectively. The simulated results are compared with previous data to interpret the trends. In particular, the diffusive time scale is used to explain the frequency dependence observed in electroporation experiments with uni- and bi-polar pulse trains. The predictions from the current model can be harnessed to help design experiments for the further understanding and quantification of DNA electrotransfer.

Superoxide flashes reveal novel properties of mitochondrial reactive oxygen species excitability in cardiomyocytes.

Superoxide flash represents quantal and bursting production of mitochondrial reactive oxygen species (ROS) instigated by transient opening of the mitochondrial permeability transition pore (mPTP). Given their critical role in metabolism, ischemia-reperfusion injury, and apoptosis, characterization of flash properties would be valuable to further mechanistic and physiological studies of this newly discovered mitochondrial phenomenon. Here we developed the flash detector FlashSniper based on segmentation of two-dimensional feature maps extracted from time-lapse confocal image stacks, and on the theory for correcting optical distortion of flash-amplitude histograms. Through large-scale analysis of superoxide flashes in cardiomyocytes, we demonstrated uniform mitochondrial ROS excitability among subsarcolemmal and intermyofibrillar mitochondria, and exponential distribution of intervals between consecutive flash events. Flash ignition displayed three different patterns: an abrupt rise from quiescence (44%), a rise with an exponential foot (27%), or a rise occurring after a pedestal precursor (29%), closely resembling action-potential initiation in excitable cells. However, the optical blurring-corrected amplitudes of superoxide flashes were highly variable, as were their durations, indicating stochastic automaticity of single-mitochondrion ROS excitation. Simultaneous measurement of mitochondrial membrane potential revealed that graded, rather than all-or-none, depolarization mirrored the precursor and the primary peak of the flash. We propose that superoxide flash production is a regenerative process dominated by stochastic, autonomous recruitment of a limited number of units (e.g., mPTPs) in single mitochondria.

The interplay of cardiac dysfunctions and hemodynamic impairments during the progression of myocardial infarction in male rats.

Myocardial infarction (MI) can induce heart failure with reduced ejection fraction (HFrEF). Systemic circulation is of importance to interact with MI-induced HFrEF. Hence, we studied the changes of myofiber stresses and peripheral hemodynamics during the progression from MI to HFrEF. MI was induced in Wistar male rats by the coronary artery ligation surgery. Physiological and hemodynamic measurements were carried out in the LV and peripheral arteries at postoperative 3 and 6 weeks, based on which LV myofiber stresses were computed and peripheral hemodynamic analysis was demonstrated. This study showed that MI significantly impaired cardiac functions and peripheral hemodynamics and altered the corresponding histological properties of cardiac wall and peripheral arterial wall, which deteriorated with time after operation. In summary, the interplay of cardiac dysfunctions and hemodynamic impairments accelerates the progression of MI-induced HF.

A Research on Delayed Thermal Depolarization, Electric Properties, and Stress in (Bi0.5Na0.5)TiO3-Based Ceramic Composites.

Depolarization behavior is one of the main shortcomings of (Bi0.5Na0.5)TiO3-based ceramics. Considering the undesirable efficiency of traditional modification methods, in this paper a series of 0-3 type ceramic composites 0.85(Bi0.5Na0.5)TiO3-0.11(Bi0.5K0.5)TiO3-0.04BaTiO3-x mol% ZnO (BNKT-BT-xZnO)) were synthesized by introducing ZnO nanoparticles. The results of the X-ray diffraction pattern (XRD) and energy dispersive spectroscopy (EDS) demonstrate that the majority of ZnO nanoparticles grow together to form enrichment regions, and the other Zn2+ ions diffuse into the matrix after sintering. With ZnO incorporated, the ferroelectric-ergodic relaxor transition temperature, TF-R, and depolarization temperature, Td, increase to above 120 °C and 110 °C, respectively. The research on temperature-dependent P-E loops verifies an attenuated ergodic degree induced by ZnO incorporation. For this reason, piezoelectric properties can be well-maintained below 110 °C. The electron backscatter diffraction (EBSD) was employed to investigate the stress effect. Orientation maps reveal the random orientation of all grains, excluding the impact of texture on depolarization. The local misorientation image shows that more pronounced strain appears near the boundaries, implying stress is more concentrated there. This phenomenon supports the hypothesis that potential stress suppresses depolarization. These results demonstrate that the depolarization behavior is significantly improved by the introduction of ZnO. The composites BNKT-BT-xZnO are promising candidates of lead-free ceramics for practical application in the future.

Optimal design and biomechanical analysis of sandwich composite metal locking screws for far cortical locking constructs.

In the interests of more flexible and less stiff bridge constructs to stimulate bone healing, the technique of far cortical locking has been designed to improve locked plating constructs in terms of stress concentration, stress shielding, and inhibition of issues around fracture healing. However, far cortical locking screws currently lack objective designs and anti-fatigue designs. This study investigates an optimization algorithm to form a special locking screw composed of various metals, which can theoretically achieve the maintenance of the excellent mechanical properties of far cortical locking constructs in terms of fracture internal fixation, while maintaining the biomechanical safety and fatigue resistance of the structure. The numerical results of our study indicate that the maximum von Mises stress of the optimized construct is less than the allowable stress of the material under each working condition while still achieving sufficient parallel interfragmentary motion. Numerical analysis of high cycle fatigue indicates that the optimized construct increases the safety factor to five. A high cycle fatigue test and defect analysis indicates that the sandwich locking constructs have better fatigue resistance. We conclude that the sandwich locking construct theoretically maintains its biomechanical safety and fatigue resistance while also maintaining excellent mechanical properties for fracture internal fixation.

Improved Non-Piezoelectric Electric Properties Based on La Modulated Ferroelectric-Ergodic Relaxor Transition in (Bi0.5Na0.5)TiO3-Ba(Ti, Zr)O3 Ceramics.

The characteristic transition from ferroelectric (FE) to ergodic relaxor (ER) state in (Bi0.5Na0.5)TiO3 (BNT) based lead-free ceramics provides an efficient approach to bring a highly ordered phase back to a disordered one. It would be rational to utilize this transition to improve relevant non-piezoelectric properties based on domain decomposition. In this work, different La contents were introduced to 0.93(Bi0.5Na0.5)TiO3-0.07Ba(Ti0.945Zr0.055)O3 ceramics (BNT-BZT-xLa) to induce evolution of ergodic degree. The results reveal that with increasing La content, both the FE-ER transition temperature TF-R and depolarization temperature Td shift towards room temperature, implying a deepened ergodic degree. By modulation of ergodic degree, thermally stimulated depolarization current experiment shows a higher current density peak, and corresponding pyroelectric coefficient increases from 2.46 to 2.81 µC/(cm2∙°C) at Td. For refrigeration, the indirect measurement demonstrates the ΔT maximum increases from 1.1 K to 1.4 K, indicating an enhanced electrocaloric effect. Moreover, the optimized energy storage effect is observed after La doping. With appearance of "slimmer" P-E loops, both calculated recoverable energy storage density Wrec and storage efficiency η increase to 0.23 J/cm3 and 22.8%, respectively. These results denote La doping conduces to the improvement of non-piezoelectric properties of BNT-based ceramics in a certain range. Therefore, La doping should be an adopted modification strategy for lead-free ceramics used in areas like refrigerator and pulse capacitors.

Hemodynamic effects of the human aorta arch with different inflow rate waveforms from the ascending aorta inlet: A numerical study.

BACKGROUND: Heart failure (HF) is a common disease globally. Ventricular assist devices (VADs) are widely used to treat HF. In contrast to the natural heart, different VADs generate different blood flow waves in the aorta. OBJECTIVE: To explore whether the different inflow rate waveforms from the ascending aorta generate far-reaching hemodynamic influences on the human aortic arch. METHODS: An aortic geometric model was reconstructed based on computed tomography data of a patient with HF. A total of five numerical simulations were conducted, including a case with the inflow rate waveforms from the ascending aorta with normal physiological conditions, two HF, and two with typical VAD support. The hemodynamic parameters, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), and the strength of the helical flow, were calculated. RESULTS: In contrast to the natural heart, numerical simulations showed that HF decreased WSS and induced higher OSI and RRT. Moreover, HF weakened helical flow strength. Pulsatile flow VADs that elevated the WSS, induced some helical flow, while continuous flow VADs could not. CONCLUSIONS: HF leads to an adverse hemodynamic environment by decreasing WSS and reducing the helical flow strength. Based upon hemodynamic effects, pulsatile flow VADs may be more advantageous than continuous flow VADs. Thus, pulsatile flow VADs may be a better option for patients with HF.

Short-Term Inhalation of Ultrafine Zinc Particles Could Alleviate Cardiac Dysfunctions in Rats of Myocardial Infarction.

It is not clear for inhalation of ultrafine metal particles in air pollution to impair human health. In the study, we aimed to investigate whether short-term (4 weeks) inhalation of ultrafine zinc particles could deteriorate the cardiac and hemodynamic functions in rats of myocardial infarction (MI). MI was induced in Wistar rats through coronary artery ligation surgery and given an inhalation of ultrafine zinc particles for 4 weeks (post-MI 4 weeks, 4 days per week, and 4 h per day). Cardiac strain and strain rate were quantified by the speckle tracking echocardiography. The pressure and flow wave were recorded in the carotid artery and analyzed by using the Womersley model. Myocardial infarction resulted in the LV wall thinning, LV cavity dilation, remarkable decrease of ejection fraction, dp/dt Max, -dp/dt Min, myocardial strain and strain rates, and increased LV end-diastolic pressure, as well as impaired hemodynamic environment. The short-term inhalation of ultrafine zinc particles significantly alleviated cardiac and hemodynamic dysfunctions, which could protect from the MI-induced myocardial and hemodynamic impairments albeit it is unknown for the long-term inhalation.

Biomechanical assessment of screw safety between far cortical locking and locked plating constructs.

With the emerging concerns for more flexible and less stiff bridge constructs in the interest of stimulating bone healing, the technique of far cortical locking has been designed to reduce the stiffness of locked plating (LP) constructs while retaining construct strength. This study utilized simulation with diaphyseal bridge plating biomechanical models to investigate whether far cortical locking causes larger screw fracture risk than LP during rehabilitation. The fracture risk of the screws in the far cortical locking constructs increases in the non-osteoporotic and osteoporotic diaphysis compared with the screws in the LP constructs.

A comparison of passive and active wall mechanics between elastic and muscular arteries of juvenile and adult rats.

The elastic abdominal aorta and muscular femoral artery are susceptible to aneurysm and atherosclerosis, respectively. The vessel wall mechanics should be an important element for the difference. The objective of the study is to demonstrate a comparison of vessel wall mechanics between elastic and muscular arteries of juvenile and adult rats to show the changes of mechanical properties relevant to aging. The passive and active mechanical tests, theoretical analysis, and histological evaluation were carried out to investigate mechanical properties of vessel walls in the abdominal aorta and carotid and femoral arteries of young and adult rats. There are stiffening femoral artery, unchanged carotid artery, and distensible abdominal aorta in adult rats as compared with the young. The opening angle has values of 54 ± 13°, 82 ± 13°, and 94 ± 13° in the abdominal aorta and carotid and femoral arteries of adult rats, respectively, as well as 80 ± 22°, 93 ± 19°, and 100 ± 23° in the young. The findings are explained by the significantly reduced width of collagen fibers in the abdominal aorta, relatively unchanged width in the carotid artery, and significantly increased width in the femoral artery of adult rats as compared with the young. In conjunction with available literatures, we concluded that inconsistency for nonlinear age-related changes of artery wall mechanics occurs between arteries of different types, which may be a risk factor for the occurrence of abdominal aorta aneurysm and femoral artery atherosclerosis.