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Symmetric Lienard system x ˙ = y − F ( x ) , y ˙ = − g ( x ) (i.e. F ( x ) and g ( x ) are odd functions) is studied. It is well known that under some hypotheses, this system has a unique limit cycle. We develop a method to give both the upper bound and lower bound of the amplitude, which is the maximal value of the x -coordinate, of the unique limit cycle. As an application, we consider van der Pol equation x ˙ = y − μ ( x 3 / 3 − x ) , y ˙ = − x , where μ > 0 . Denote by A ( μ ) the amplitude of its unique limit cycle, then for any μ , we show that A ( μ ) 2.0976 and for μ = 1 , 2 , we show that A ( μ ) > 2 . Both the upper bound and the lower bound improve the existing ones.

We study a stochastic analogy of the famous center problem of Dulac for quadratic differential equations in the plane. We introduce the concept of center for systems of stochastic differential equations of Ito's type on the plane, called stochastic center. We derive a criterion for the existence of such a center. We apply it to obtain necessary and sufficient conditions for quadratic stochastic differential equations in dimension 2.

Aortopathy represents an important cause of mortality in industrialized countries, with a number of genes identified as predispose factors. It can be difficult to identify the genetic lesions underlying this disorder, particularly when the phenotype is atypical. The present study performed targeted next-generation sequencing of 428 genes associated with cardiovascular diseases in a family with aortopathy, the proband of which presented with abdominal aortic aneurysm rupture only, with tissue fragility noted in surgery. After targeted capture, sequencing and bioinformatics analysis, a missense mutation, p.A1259T, was identified in the collagen type III α1 (COL3A1) gene and co-segregated with the disease in the family. Crystal structure modeling revealed abnormal hydrogen bonds generated by the mutation, which likely affected the spatial structure of the procollagen C-propeptide. Mutations in the procollagen C-propeptide are rare and genotype-phenotype correlation may explain the atypical manifestations of affected individuals. The results of the present study suggested that targeted gene capture combined with next-generation sequencing can serve as a useful technique in the genetic diagnosis of aortopathy, particularly in the content of an atypical phenotype.

Objective The aim of this study was to explore an innovative cell-seeding technology applied on artificial vascular scaffolds. Methods Scaffolds were fabricated by electrospinning polycaprolactone (PCL) and seeded with rat endothelial progenitor cells differentiated from adipose-derived stem cells. Then, we modified the PCL scaffolds through the use of alginate hydrogel conglutinating cells (AHCC), a blank alginate hydrogel coating (BAHC), and natural sedimentation seeding cells (NSSC). The blank PCL (BP) scaffolds without any modifications were considered the blank control group. After modification, the scaffolds were implanted in a rat model. The implanted scaffolds were harvested and observed using histological and immunohistochemical methods and scanning electron microscopy (SEM) at 1, 2, and 4 weeks after implantation, respectively. Results The best regeneration and configuration of the endothelium tissue and the most similar morphology to that of natural endangium was observed qualitatively in the AHCC scaffolds. The BP scaffolds had qualitatively the worst regeneration and configuration and the most dissimilar morphology at the same time point. In the AHCC group, cells could adhere directly on the inner surface of the vascular scaffolds, eliminating the time delay via the NSSC method prior to cell adhesion. Conclusion AHCC are an effective method for seeding cells on vascular scaffolds and can eliminate the time delay for cell adhesion. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

Objective Previous studies have suggested that stromal-derived factor 1 (SDF1) plays a pivotal role in abdominal aortic aneurysm (AAA) development. The SDF1-3′A polymorphism (G to A, rs1801157), located in the 3′ untranslated region, could influence the expression of SDF1. The aim of our study was to investigate the relationship of SDF1-3′A polymorphism with the risk of AAA occurrence and size. Methods A total of 205 AAA patients and 216 age- and sex-matched controls were recruited. The SDF1-3′A polymorphism was evaluated by polymerase chain reaction, followed by restriction enzyme analysis. Results The frequency of A allele was similar between groups. The genotype distribution also displayed no statistically significant differences under both the dominant model (odds ratio [OR], 0.922; P = .678) and the recessive model (OR, 1.617; P = .300). The multiple logistic regression analysis indicated that the association between the polymorphism and AAA remained insignificant when applied to the dominant model. However, AAA patients with GG genotype were more likely to develop aneurysms larger than 50 mm (OR, 0.497; P = .014). AAA patients with SDF1-3′A allele have reduced plasma SDF1α levels. In addition, plasma SDF1α levels were positively correlated with AAA size. Conclusions Our study suggests that SDF1-3′A polymorphism is associated with size but not occurrence of AAA, providing further evidence that SDF1 is implicated in AAA progression.

Yepeng Zhang,1 Hanfei Tang,1 JianPing Zhou,2 Zhao Liu,1 Changjian Liu,1 Tong Qiao,1 Min Zhou1 1Department of Vascular Surgery, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 2Department of General Surgery, Yixin People’s Hospital, Yixin, People’s Republic of China Background: Endovascular option has been proposed for a very limited and selected number of Stanford type A aortic dissection (TAAD) patients. We have performed a computed tomography (CT)-based TAAD study to explore appropriate endograft configurations for the ascending aortic pathology. Methods: TAAD patients treated with optimal CT scans were retrospectively reviewed, and their entry tears (ETs) were identified using three-dimensional and multiplanar reconstructions in an EndoSize workstation. After generating a centerline of flow, measurements, including numerous morphologic characteristics of anatomy, were evaluated and a selected subset of patients were determined to be suitable for endovascular treatments. Proximal diameter and distal diameter of endograft were selected based on diameters measured at the ET level and at the innominate artery (IA) level, with 10% oversizing with respect to the true lumen, but not exceeding the original aortic diameter. The length of the endograft was determined by the distance from the sinotubular junction to IA. Results: This study covered 126 TAAD patients with primary ET in ascending aorta, among which, according to the assumed criteria, 48 (38.1%) patients were deemed to be suitable for endovascular treatment. The diameters of ascending aorta from the sinotubular junction to the IA level presented a downward trend, and the proximal diameters differed significantly from distal diameters of the endograft for TAAD (39.9versus 36.2mm, P

We examine near-inertial variability of the meridional overturning circulation in the South China Sea (SCSMOC) using a global 1 / 12° ocean reanalysis. Based on wavelet analysis and power spectrum, we suggest that deep SCSMOC has a significant near-inertial band. The maximum amplitude of the near-inertial signal in the SCSMOC is nearly 4 Sv. The spatial structure of the signal features regularly alternating counterclockwise and clockwise overturning cells. It is also found that the near-inertial signal of SCSMOC mainly originates from the region near the Luzon Strait and propagates equatorward at a speed of 1–3 m s−1. Further analyses suggest that the near-inertial signal in the SCSMOC is triggered by high-frequency wind variability near the Luzon Strait, where geostrophic shear always exists due to Kuroshio intrusion.

A tidal flow constructed wetland (TFCW), a commonly applied system to clean wastewater, contains a substrate to assist pollutants removal, while the choice of substrate affects the formation of bacterial biofilms. Herein, activated alumina-TFCW (A-TFCW) with hydraulic load of 1.35 m3/(m2·d) parallel with shale ceramisite (S-TFCW) was investigated for treating domestic wastewater, aiming to enhance simultaneous long-term removal of organics, nitrogen and phosphorus. A-TFCW achieved significantly higher COD, NH4+-N, TN and TP removal efficiency than S-TFCW, with the removal efficiency of 85.9% COD, 85.4% NH4+-N, 72.8% TN and 96.4% TP respectively. Denitrifying bacteria dominated in both formed biofilms, with higher relative abundance of nitrifying bacteria and denitrifying bacteria in A-TFCW. These results demonstrated that AA substrate was more suitable to be applied in enhancing the removal performance in TFCW for the treatment of domestic wastewater.

In varicose veins, vascular smooth muscle cells (VSMCs) often show abnormal proliferative and migratory rates and phenotypic transition. This study aimed to investigate whether microRNA (miR)-202 and its potential target, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), were involved in VSMC phenotypic transition. miR-202 expression was analyzed in varicose veins and in VSMCs conditioned with platelet-derived growth factor. The effect of miR-202 on cell proliferation and migration was assessed. Furthermore, contractile marker SM-22α, synthetic markers vimentin and collagen I, and PGC-1α were analyzed by Western blot analysis. The modulation of PGC-1α expression by miR-202 was also evaluated. In varicose veins and proliferative VSMCs, miR-202 expression was upregulated, with decreased SM-22α expression and increased vimentin and collagen I expression. Transfection with a miR-202 mimic induced VSMC proliferation and migration, whereas a miR-202 inhibitor reduced cell proliferation and migration. miR-202 mimic constrained luciferase activity in HEK293 cells that were cotransfected with the PGC-1α 3'-untranslated region (3'-UTR) but not those with mutated 3'-UTR. miR-202 suppressed PGC-1α protein expression, with no influence on its messenger RNA expression. PGC-1α mediated VSMC phenotypic transition and was correlated with reactive oxygen species production. In conclusion, miR-202 affects VSMC phenotypic transition by targeting PGC-1α expression, providing a novel target for varicose vein therapy.

To compare the short-term efficiency of two different endovascular repairs for type B aortic dissection involving the left subclavian artery. From February 2013 to March 2016, a cohort of 43 patients with TBADs involving the LSA underwent thoracic endovascular aortic repair (TEVAR) in two departments, consisting of 22 (Group A) with chimney grafts (CGs) and 21 (Group B) with single-branched stent graft (SBSG). Results of the two groups in perioperative and follow-up period (≥ 3 months) were comparatively analyzed, especially on aortic remodeling. Endoluminal repair of the two groups was successfully carried out. The median follow-up period was 19 months (range, 3–43 months) in Group A and 12 months in Group B (range, 6–32 months). During the TEVAR, one CG compression occurred in Group A and one type I endoleak in Group B. During follow-up, four complications occurred in Group A (two CGs occlusion, one type I endoleak and one death from dissecting aneurysm rupture), compared with two occurred in Group B (one sidearm graft twist and one death from myocardial infarction). Complete thrombosis of the false lumen (FL) in thoracic aorta was revealed in 83.3% (15/18) cases in Group A and 89.5% (17/19) in Group B. Partial thrombosis of the FL was revealed in 16.7% (3/18) cases in Group A and 10.5% (2/19) in Group B. In the abdominal aorta, complete thrombosis of the FL was noted in 23.1% (3/13) cases in Group A and 36.4% (4/11) in Group B. Partial thrombosis of the FL was revealed in 76.9% (10/13) cases in Group A and 63.6% (7/11) in Group B. Significant true lumen re-expansion and false lumen regression were observed in different levels of the descending aorta by computed tomography angiography (CTA) in both Groups A and B (P

In recent years, there has been increasing demand for personalized anatomy modelling for medical and industrial applications, such as ergonomics device development, clinical radiological exposure simulation, biomechanics analysis, and 3D animation character design. In this study, we constructed deformable torso phantoms that can be deformed to match the personal anatomy of Chinese male and female adults. The phantoms were created based on a training set of 79 trunk computed tomography (CT) images (41 males and 38 females) from normal Chinese subjects. Major torso organs were segmented from the CT images, and the statistical shape model (SSM) approach was used to learn the inter‐subject anatomical variations. To match the personal anatomy, the phantoms were registered to individual body surface scans or medical images using the active shape model method. The constructed SSM demonstrated anatomical variations in body height, fat quantity, respiratory status, organ geometry, male muscle size, and female breast size. The masses of the deformed phantom organs were consistent with Chinese population organ mass ranges. To validate the performance of personal anatomy modelling, the phantoms were registered to the body surface scan and CT images. The registration accuracy measured from 22 test CT images showed a median Dice coefficient over 0.85, a median volume recovery coefficient (RC (vlm)) between 0.85 and 1.1, and a median averaged surface distance (ASD)

Aim Vascular endothelial-cadherin (VE-cadherin) is specifically expressed by outgrowth endothelial cells (OECs). Zwitterionic stent showed high antifouling and excellent blood compatibility. Therefore, we hypothesized that anti-VE-cadherin antibody-coated zwitterionic stents (VE-cad-Z stents) would promote re-endothelialization, reduce neointimal formation, and resist thrombus. Methods VE-cad-Z stents were examined using platelet adhesion test, platelet activation, and OEC capture ability in vitro. In vivo effect of VE-cad-Z stents on re-endothelialization, thrombus-resistance, and neointima hyperplasia was investigated in left common carotid arteries of rabbits (n=15). Results In vitro, VE-cad-Z stents showed better platelet-resistance and OEC-capture ability (DNA concentration: 297.23±22.71 versus 67.49±15.26 ng/µL, P＜0.01). In vivo, VE-cad-Z stents exhibited better patency rate than bare metal stents (BMS) (15/15 versus 12/15), and it significantly reduced platelet adhesion and neointima formation (neointima area: 1.13±0.05 versus 1.00±0.05mm(2), P＜0.01 and 3.04±0.11versus 1.05±0.06mm(2), P＜0.01, at 3 and 30 days, respectively; % stenosis: 20.99±0.98 versus 18.72±0.97, P＜0.01 and 56.46±2.20 versus 19.45±1.24, P＜0.01, at 3 and 30 days, respectively). Conclusion These data suggested that VE-cad-Z stents could specifically capture OECs, consequently promote endothelial healing, and also reduce platelet adhesion and neointima formation.

Background A custom-made unibody single-branch endograft (USBE) could provide great gains in the landing zone, while maintaining a left subclavian artery (LSA) perfusion in some patients with Stanford type B dissections (TBADs). We performed a computed tomography (CT)-based planning study to determine the proportion of TBAD patients who could benefit from this custom-made USBE and ascertained the possibility of an off-the-shelf USBE in an emergency setting. Methods We carried out a retrospective study of TBAD patients with optimal CT scans at our center from 2007 to 2013. Patients' CT scans were analyzed using 3-dimensional reconstruction software. After generating a centerline of flow, measurements (including numerous morphologic characteristics of anatomy) were evaluated. A selected subset of patients suitable for USBE was determined. Finally, the most frequently used configurations of endografts were figured out by subgroup analysis. Results A total of 314 patients with optimal digital imaging communications in medicine (DICOM) data were included in our study. The main primary entry tears (MPETs) were located at 22.8 ± 17.3 and 36.3 ± 18.6 mm distal to the LSA and the left common carotid artery, respectively. Overall, 169 (54.2%) patients with MPET distal to LSA (＞20 mm) could be treated by tubular stent grafts. Of the 143 patients who had intimal tears adjacent to the LSA (≤20 mm), there were 111 (35.4%) patients who could benefit from treatment using USBE based on our selection criteria. Subgroup analysis estimated the number of graft configurations needed to treat a proportion of patients: 1 design would treat 6.7% of the population, 5 designs would treat 23.1%, 10 designs would treat 37.6%, and 20 configurations would treat 54.8% . Conclusions In all, 35.4% patients with TBAD could potentially benefit from USBE. The use of off-the-shelf endografts might be possible in cases of emergency, given the evidence of recurrent configurations.

In this paper we study a class of planar piecewise smooth quadratic integrable non-Hamiltonian systems, which have a center. By using the averaging method, we give an estimation of the number of limit cycles which bifurcate from the above periodic annulus under the polynomial perturbation of degree n . Our estimation is linear depending on n and it is at least twice the associated estimation of smooth systems.

Sub-inertial currents (SICs) over the continental shelf of the northern South China Sea (NSCS) are investigated using the in-situ current observations of acoustic Doppler current profiler (ADCP) mooring arrays off the Pearl River Estuary in 2006 and 2007. The survey was carried out in four separate time periods: summer, winter, spring (before the onset of the southwesterly monsoon), and fall (after the establishment of the northeasterly monsoon). The observations showed that the current directions were generally along the shelf, consistent with the directions of monsoonal winds. The currents were also affected by a few of mesoscale eddy events. In summer 2006, the volume transport was northeastward with a mean magnitude of 1.4 Sv through a cross-shelf section from the site of the depth of 135 m to the coast; in winter 2006/2007, spring 2007 and fall 2007, the volume transports were all southwestward with magnitudes of 2.0, 2.1, and 0.9 Sv, respectively, through a cross-shelf section from the site of the depth of 290 m to the coast. The standard deviations of the SICs were generally smaller than the velocities of the mean currents, and the variability of SICs showed significant correlation with the local sea surface winds. No persistent counter-wind currents were observed in the study area during the fall and winter observational periods.

The aim of the present study was to explore the effects of pannexin1 (Px1) protein channels on osteogenic differentiation of mesenchymal stem cells (MSCs) under mechanical stress stimulation. MSCs were isolated from Sprague Dawley rats (3 weeks old, weighing 100–120 g) and cultured in vitro. A safe concentration of carbenoxolone was determined (CBX, an inhibitor of Px1 channels; 100 µM) on MSCs using the Cell Counting Kit-8 (CCK8) method. MSCs were divided into 6 groups: Control, stress (4,000 µ strain), and stress following 3, 6, 12, and 24 h pretreatment with CBX. Stress groups were stimulated with mechanical stress for 15 min. Alkaline phosphatase (ALP) activity, type I collagen expression, intracellular calcium ion (Ca2+) concentration, Px1 expression, p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated phosphorylation were determined. ALP activity was increased in the stress group, and this was prevented by pretreatment with CBX. Similarly, stress-induced increases in type I collagen expression, Ca2+ concentration, Px1 expression, and p38 MAPK phosphorylation decreased in the presence of CBX. ERK phosphorylation was decreased by stress, however was not affected by CBX treatment. Altogether, the results suggest that mechanical stress promoted the osteogenic differentiation of MSCs, and this promotion was inhibited by pretreatment with CBX, possibly through regulating the phosphorylation of p38 MAPK.

In this paper, we study the complexity of generalized center problem by looking for the lower bounds of the maximal possible saddle order \(M(p,q,n)\) of planar polynomial differential equations of arbitrary degree \(n\) admitting any \(p:-q\) saddle type resonance between the eigenvalues. We prove that, for any given positive integers \(p\) and \(q\), and sufficiently big integer \(n\), \(M(p,q,n)\) can grow at least as rapidly as \(2n^2\). This result significantly improves all the known lower bounds which are at most \(n^2+O(n)\).

A rapid, sensitive and high-throughput liquid chromatography–tandem mass spectrometry was established and validated to assay the concentrations of 3,29-dibenzoyl rarounitriol in rat plasma. Plasma samples were processed by liquid–liquid extraction with ethyl acetate and separated on a Hypersil Gold C18 column (50 × 4.6 mm, 3 µm) at an isocratic flow rate of 0.5 mL/min using methanol–10 mm ammonium acetate–formic acid (90:10:0.1, v/v/v) as mobile phase. The total run time was 5 min for each sample. MS/MS detection was accomplished in selected reaction monitoring mode with positive electrospray ionization. The calibration curve was linear over the concentration range of 0.125–50 ng/mL with lower limit of quantification of 0.125 ng/mL. The intra- and inter-day precisions were

In this paper, we study the limit cycles for m-piecewise discontinuous polynomial Lienard differential systems of degree n with m/2 straight lines passing through the origin whose slopes are $$\tan (\alpha + 2j\pi /m)$$ for $$j = 0, 1, \ldots , m/2 -1$$ , and prove that for any positive even number m, if $$\sin ( m\alpha /2)\ne 0$$ , then there always exists such a system possessing at least $$\left[ \frac{1}{2}(n-\frac{m-2}{2}) \right] $$ limit cycles. This result verifies a conjecture proposed by Llibre and Teixerira (Z Angew Math Phys 66:51–66, 2015).

Objectives To report the midterm safety and efficacy of the Aegis™-B (Microport, Shanghai, China) unibody bifurcated stent graft for endovascular treatment of isolated abdominal aortic dissection (IAAD). Background Isolated abdominal aorta dissection (IAAD) is a rare event. Endovascular stent grafts seem to offer an efficient therapeutic approach to treat IAAD. However, the relatively small diameter of the infrarenal aorta and aortic bifurcation remains the main anatomical limitation to endovascular repair. Methods Between 2008 and 2015, we retrospectively evaluated 32 IAAD patients (21 men; mean age 58 ± 18 years), who underwent endovascular repair using Aegis™-B unibody bifurcated stent graft. Narrow proximal landing zone and narrow distal aorta was present in 11 (34.4%) patients and 10 (31.3%) patients, respectively. In the follow-up period, aortic remodeling was observed with computed tomography angiography. Results All patients were treated by endovascular means, with a primary technical success rate of 100%. During a mean follow-up period of 30.71 ± 16.36 months (range, 8–56 months), no death, rupture, stent fracture, material failure, or device migration was observed. Complete false lumen thrombosis was observed in all patients at 1 year, and all patients were free from false lumen growth in the follow-up. Conclusions Endovascular treatment of IAAD using the Aegis™-B system appears to be safe and effective. Results from this study suggest this algorithm can provide stable, secure fixation for IAAD patients with narrow proximal landing zone, and distal aorta.

Water-soluble polysaccharide was isolated from Semen cassiae using water for extraction and ethanol for deposition. The optimized conditions for polysaccharide isolation by orthogonal experiments were a sample to liquid ratio of 1:30 at 80°C for 3.5 hours; the yield of polysaccharide from Semen cassiae under these conditions was 5.46%. Different polysaccharides (SCPW-1, SCPW-2, SCPW-3, SCPW-4, SCPW-5, SCPS-1, SCPS-2) were obtained from the extract (i.e., crude polysaccharide) by DEAE-cellulose column chromatography. The polysaccharides obtained showed different structures by Fourier transform infrared therein the five elected from the seven kinds separated. The antioxidant activities of the extract were evaluated. The scavenging rates of the present extract on hydroxyl and superoxide were 43.32% and 64.97%, respectively, at a concentration of polysaccharide of 94.03 μg/mL, which was better than vitamin C at the same concentration. The scavenging rate of the present extract on 1,1-diphenyl-2-picrylhydrazyl was 13.33% at a polysaccharide concentration of 94.03 μg/mL, which was less than vitamin C at the same concentration.

Several observational studies have demonstrated that lipid-modifying therapy may improve long-term survival in abdominal aortic aneurysm (AAA) patients after repair. We carried out a systematic review and meta-analysis of studies evaluating the effect of lipid-modifying therapy on long-term mortality. We conducted a systematic search of multiple databases up to April 2014. Studies that evaluated exposure to lipid-modifying therapy, reported mortality data and hazard ratio (HR) or provided survival curve for their estimation were included in the meta-analysis. Pooled HR estimates with 95 % confidence intervals (CIs) were calculated using the random-effects model. Eight studies (seven cohorts, one post hoc study of a randomization controlled trial) reporting 2,605 patients on lipid-modifying therapy were included. Meta-analysis showed a significant 39 % reduction in long-term mortality with lipid-modifying therapy (HR 0.61; 95 % CI 0.51–0.73). After exclusion of one study which was contributing to considerable heterogeneity, a significant 33 % reduction in mortality risk was a more conservative, consistent estimate (HR 0.67; 95 % CI 0.59–0.77). Meta-analysis of studies supports a protective role of lipid-modifying therapy on mortality risk after AAA repair. Aggressive lipid intervention should be recommended to those who receiving AAA repair.

The integrability of a class of cubic Lotka–Volterra systems x = x ( 1 − a 0 x 2 − a 1 x y − a 2 y 2 ) , y = y ( − λ + b 0 x 2 + b 1 x y + b 2 y 2 ) , is studied. For odd λ satisfying λ ≥ 3 , we derive the necessary and sufficient conditions for the integrabilities of the above systems.

Synthesis analyses were performed to examine characteristics of tidal and subtidal currents at eight mooring sites deployed over the northern South China Sea (NSCS) continental shelf in the 2006–2007 and 2009–2010 winters. Rotary spectra and harmonic analysis results showed that observed tidal currents in the NSCS were dominated by baroclinic diurnal tides with phases varying both vertically and horizontally. This feature was supported by the CC-FVCOM results, which demonstrated that the diurnal tidal flow over this shelf was characterized by baroclinic Kelvin waves with vertical phase differences varying in different flow zones. The northeasterly wind-induced southwestward flow prevailed over the NSCS shelf during winter, with episodic appearances of mesoscale eddies and a bottom-intensified buoyancy-driven slope water intrusion. The moored current records captured a warm-core anticyclonic eddy, which originated from the southwestern coast of Taiwan and propagated southwestward along the slope consistent with a combination of β-plane and topographic Rossby waves. The eddy was surface-intensified with a swirl speed of >50 cm/s and a vertical scale of ∼400 m. In absence of eddies and onshore deep slope water intrusion, the observed southwestward flow was highly coherent with the northeasterly wind stress. Observations did not support the existence of the permanent wintertime South China Sea Warm Current (SCSWC). The definition of SCSWC, which was based mainly on thermal wind calculations with assumed level of no motion at the bottom, needs to be interpreted with caution since the observed circulation over the NSCS shelf in winter included both barotropic and baroclinic components.

We investigated the hypothesis that an antioxidant, Vitamin C, could attenuate abdominal aortic aneurysm (AAA) development in a rat model.An AAA model induced by intraluminal infusion was created in 36 male Sprague Dawley rats, which were randomly distributed into three groups: Sham (saline infused, placebo treated), Control (elastase infused, placebo treated), and Vitamin C (elastase infused, vitamin C treated). Vitamin C and placebo were intraperitoneally injected, initiating 1 wk before the infusion and continuing throughout the study. The aortic dilatation ratio was measured, and aortic tissues were further examined using biochemical and histologic techniques.Vitamin C attenuated the development of AAA, decreasing maximal aortic diameter by 25.8% (P 0.05) and preserving elastin lamellae (P 0.05). Vitamin C also decreased 8-hydroxyguanine (a marker of oxidative damage to DNA) and 8-isoprostane content (a marker of oxidative stress) in aortic tissues (P 0.05, respectively). The proteins of matrix metalloproteinase (MMP)-2, MMP-9, and interleukin 6 were markedly downregulated (P 0.05, respectively), accompanied with notably reduced messenger RNA expression of tumor necrosis factor-α, MMP-2/9, and interleukin 1β (P 0.05, respectively). However, messenger RNA of tissue inhibitors of metalloproteinase-1 and tissue inhibitors of metalloproteinase-2 were both significantly upregulated in Vitamin C group. Vitamin C treatment had no significant effect on systolic blood pressure (P 0.05).Vitamin C attenuated AAA development in an elastase-induced rat model via crucial protective effect, which was mediated by an increased level of antioxidant in cooperation with preserving elastin lamellae, inhibiting matrix-degrading proteinases and suppressing inflammatory responses.

This paper is concerned with the bifurcation of limit cycles from a quadratic reversible Lotka-Volterra system with two centers of genus one under small quadratic perturbations. It shows that the cyclicities of each period annulus and two period annuli of the considered system under small quadratic perturbations are two, respectively. This not only gives at least partially a positive answer to an open conjecture, but also improves the corresponding results in the literature. In addition, we present the configurations of limit cycles of the perturbed system as (2, 0), (1, 1), (1, 0), (0, 2), (0, 1) and (0, 0), where $(i,\, j)$ indicates that the perturbed system has $i$ limit cycles surrounding the positive singularity while it has $j$ limit cycles surrounding the negative one.

In this paper, we study the topology of isochronous centers of Hamiltonian differential systems with polynomial Hamiltonian functions [Formula: see text] such that the isochronous center lies on the level curve [Formula: see text]. We prove that, in the one-dimensional homology group of the Riemann surface (removing the points at infinity) of level curve [Formula: see text], the vanishing cycle of an isochronous center cannot belong to a subgroup generated by those small loops such that each of them is centered at a removed point at infinity of having one of the two special types described in the paper, where [Formula: see text] is sufficiently close to [Formula: see text]. Besides, we present some topological properties of isochronous centers for a large class of Hamiltonian systems of degree [Formula: see text], whose homogeneous parts of degree [Formula: see text] contain factors with multiplicity of no more than [Formula: see text]. As applications, we study the nonisochronicity for some Hamiltonian systems with quite complicated forms which are usually very hard to handle by the classical tools.

Sub-Nyquist sampling based wideband spectrum sensing can usually be summarized as two steps. The first step estimates the signal power spectrum. The second step uses the energy detection method to make a decision. The traditional method usually adopts the least square algorithm to estimate the power spectrum. In order to reduce the computational complexity of the power spectrum estimation, a novel algorithm is proposed to replace the least square algorithm. We find the system matrix of Multi-Coset Sampling (MCS) based power spectrum estimation has a special structure. Its row vectors are all selected from the row vectors of the Discrete Fourier Transform (DFT) matrix. We exploit this special structure and use Fast Fourier Transform (FFT) to reduce the computational complexity of power spectrum estimation. Simulation shows the proposed algorithm can achieve the spectrum sensing performance similar to the traditional method at much lower computational complexity.

Complex aortic aneurysms are difficult to treat endovascularly and so techniques have been developed to broaden the management options. We report a case of 51-year-old man with several thoracoabdominal aortic aneurysms (TAAAs) who underwent endovascular repair with “off-label” stent grafts. Three aortic stent grafts and four branched stent grafts were used in the procedure using chimney and periscope techniques. The patient was followed for three years with regular computed tomography angiography (CTA). Scans at 3 and 12 months showed that the TAAAs were repaired and all visceral arteries were patent. Although, scans at the two- and three-year follow-ups showed that the stent graft in the superior mesenteric artery was occluded, the patient did not have any complications probably as a result of coeliac artery compensation.

We experimentally investigate the effects of the surface roughness of gold thin films on the properties of surface plasmon resonance. By annealing at different temperatures, film samples with different surface morphologies are obtained. Specifically, due to the diffusion of the gold atoms towards the films’ surface, the surface root-mean-square roughness decreases with the increasing annealing temperature. Then, we measure the surface plasmon resonance of the samples. The results show that the resonance angle of the surface plasmon resonance is sensitive to the root-mean-square roughness, and it gradually decreases by reducing the surface root-mean-square roughness.

The aim of the present study was to investigate whether chronic administration of basic fibroblast growth factor (bFGF) following angioplasty in a dog model of atherosclerotic iliac stenosis may restore endothelium function and prevent restenosis (RS). In total, 40 dogs with atherosclerotic stenosis of the right iliac arteries were used in the study. A total of 20 dogs underwent histological examination of the lumen areas prior to (n=10) and immediately following angioplasty (n=10). Intravenous bFGF was administered to 10 dogs (bFGF group) and an additional 10 dogs received vehicle injection (control group). Animals in the two groups were sacrificed 42 days following surgery for in vitro analysis of vascular reactivity and morphometric assessment of the histological cross-sectional areas. The bFGF group exhibited significantly greater maximal endothelium-dependent acetylcholine-induced relaxation (Emax, 43±9%) when compared with the control group (Emax, 8±6%; P

The purpose of this study was to determine whether myeloid differentiation factor88-dependent Toll-Like Receptor-4 (TLR-4) signaling contributed to the inhibition of abdominal aortic aneurysm (AAA) by Tanshinone IIA (Tan IIA).Male Sprague-Dawley rats (n = 12 / group) were randomly distributed into three groups: Tan IIA, control, and sham. The rats from Tan IIA and control groups under-went intra-aortic elastase perfusion to induce AAAs, and those in the sham group were perfused with saline. Only the Tan IIA group received Tan IIA (2 mg / rat / d). Aortic tissue samples were harvested at 24 d after perfusion and evaluated using reverse transcriptase-polymerase chain reaction, Western blot, immunohistochemistry and immunofluorescence.The over-expression of Toll-Like Receptor-4 (TLR-4), Myeloid Differentiation factor 88 (MyD88), Phosphorylated Nuclear Factor κB (pNF-κB) and Phosphorylated IκBα (pIκBα) induced by elastase perfusion were significantly decreased by Tan IIA treatment.Tan IIA attenuates elastase-induced AAA in rats possibly via the inhibition of MyD88-dependent TLR-4 signaling, which may be one potential explanation of why Tan IIA inhibits AAA development through multiple effects.Hintergrund: Das Ziel dieser Studie war es, festzustellen, ob das vom myeloischen Differenzierungsfaktor88 (MyD88)-abhängige Toll-like-Rezeptor-4 (TLR-4) Signal zur Hemmung des Bauchaortenaneurysmas (BAA) durch Tanshinone IIA (Tan IIA) beiträgt. Material und Methoden: Männliche Sprague-Dawley Ratten (n = 12 pro Gruppe) wurden zufällig in drei Gruppen aufgeteilt: Tan IIA, Kontrolle und Scheinbehandlung. Die Ratten von Tan IIA und der Kontrollgruppe wurden einer intraaortalen Elastase Perfusion unterzogen, um ein BAA zu induzieren, und in der Gruppe mit Scheinbehandlung wurde mit Kochsalzlösung perfundiert. Nur die Tan IIA Gruppe erhielt Tan IIA (2 mg / Ratte / Tag). Aortale Gewebeproben wurden 24 Tage nach Perfusion genommen und mit Reverse Transkriptase Polymerase Kettenreaktion, Western Blot, Immunhistochemie und Immunfluoreszenz ausgewertet. Ergebnisse: Die Überexpression von TLR-4, MyD88, phosphoryliertem nuclear factor kappaB (pNF-κB) und phosphoryliertem IκBα (pIκBα), welche durch Elastase Perfusion induziert waren, wurden wesentlich durch Tan IIA Behandlung verringert. Schlussfolgerungen: Tan IIA dämpft das Elastase-induzierte BAA in Ratten möglicherweise über die Hemmung der MyD88-abhängigen TLR-4-Signalisierung, was eine Erklärung dafür sein kann, warum Tan IIA die Entwicklung eines BAA durch mehrere Effekte verringert.

Successful engineering of a small-diameter vascular graft is still a challenge despite numerous attempts for decades. The present study aimed at developing a tissue-engineered vascular graft (TEVG) using autologous outgrowth endothelial cells (OECs) and a hybrid biodegradable polymer scaffold. OECs were harvested from canine peripheral blood and proliferated in vitro, as well as identified by immunofluorescent staining. Electrospun hybrid chitosan/poly(ɛ-caprolactone) (CS/PCL) nanofibers were fabricated and served as vascular scaffolds. TEVGs were constructed in vitro by seeding OECs onto CS/PCL scaffolds, and then implanted into carotid arteries of cell-donor dogs (n=6). After 3 months of implantation, 5 out of 6 of TEVGs remained patent as compared with 1 out of 6 of unseeded grafts kept patent. Histological and immunohistochemical analyses of the TEVGs retrieved at 3 months revealed the regeneration of endothelium, and the presence of collagen and elastin. OECs labeled with fluorescent dye before implantation were detected in the retrieved TEVGs, indicating that the OECs participated in the vascular tissue regeneration. Biomechanical testing of TEVGs showed good mechanical properties that were closer to native carotid arteries. RT-PCR and western blot analysis demonstrated that TEVGs had favorable biological functional properties resembling native arteries. Overall, this study provided a new strategy to develop small-diameter TEVGs with excellent biocompatibility and regeneration ability.

In situ observations, satellite data, and the output from an eddy-resolving ocean circulation model were used to study the generations and propagations of an anticyclonic eddy in the northern South China Sea (NSCS) during the winter of 2009-2010. In the NSCS, the anticyclonic eddy firstly appeared to the west of the Luzon Strait, migrated generally along the continental slope and dissipated around the Xisha Archipelago. The evolution of the warm eddy contains three phases: development, maturation, and decay. The eddy mainly stayed near 119.7 degrees E in December and then gradually moved to 118.7 degrees E until January 15, when its intensity, as indicated by the thermocline temperature and salinity anomalies, increased significantly, reflecting the growth of the eddy. The eddy reached its peak on January 15 and persisted until February 23. During this period, the eddy propagated westward to 116.4 degrees E. After, the warm eddy weakened significantly and dissipated finally near the Xisha Archipelago.

In this paper, we prove that the cyclicity of period annuli for system d x d t = y , d y d t = − ( a x + b x 3 + c x 5 ) under perturbations of polynomials with degree n is not more than 54 n − 13 (taking into account the multiplicity), where a , b , c ∈ R with c ≠ 0 such that the unperturbed systems have at least one center.

We report our three-year experience with the visceral hybrid procedure for patients with thoracoabdominal aortic aneurysms, dissections and Takayasu's arteritis. We also evaluate and discuss the outcomes of hybrid procedures. Hybrid procedures include debranching of the visceral or renal arteries followed by endovascular repair of the disease. The surgical strategy was designed individually to reduce trauma and minimize stent coverage area. A series of 11 patients (9 men, mean age 52 years) were treated between June 2008 and September 2011. The pathologies were aneurysmal disease (thoracoabdominal aortic aneurysms) (5, 45.5%), aortic dissection (thoracoabdominal aortic dissection) (4, 36.4%) or true/false aneurysm formation after Takayasu's arteritis (2, 18.2%). Simultaneous approach (9, 81.8%) and staged approach (2, 18.2%) were performed. The mean follow-up was 13.5 months (range 1–36). The technical success was 100%. Stent grafts were implanted in the entire or part of the thoracoabdominal aorta. The overall mortality rate was 9.1% (1/11) with no aneurysm-related death. The permanent paraplegia and bypass graft occlusion rate was 0%. The overall morbidity was 36.4% with two endoleaks (2/11, 18.2%). In conclusion, hybrid procedures can minimize surgical invasiveness in treatments of thoracoabdominal aortic pathologies, and it is a safe method with acceptable morbidity and mortality.

Objective To investigate the abnormal expressions of Tie1 on the valves of great saphenous varicose vein, and to discuss the relationship between the phenomenon and pathogenesis of varicose vein of lower extremity. Methods Varicose veins group 18 samples, normal control group 14 samples. Immunohistochemistry staining has investigated the expression of CD31 and Tie1 in the first valves of great saphenous veins. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) has checked mRNA expression of Tie1. Western blot has checked the expression of Tie1 protein in venous valves. Results In normal control group valves, there was no difference between proximal and distal sides endothelium, which expressing CD31 in both valvar basement and valve cusp (positive endothelial cells [ECs] percentage: P > 0.05, P > 0.05). However, the endothelium of the proximal side demonstrates Tie1 stronger than distal side in valvar basement (positive ECs percentage: P < 0.05), which was not found at valve cusp (positive ECs percentage: P > 0.05). In varicose veins group, the endothelium of proximal side cells expresses CD31 weaker than distal side at both valvar basement and valve cusp (positive ECs percentage: P < 0.05, P < 0.05) besides the morphological alteration of valves. Moreover, it expresses Tie1 much weaker than diatal side (positive ECs percentage: P < 0.01). Semi-quantitative RT-PCR showed that valves of varicose veins group expressed Tie1 much weaker than the normal control group ( P < 0.01). Western blot could not detect the expression of Tie1 in venous valves. Conclusion The decreasing expression of Tie1 may play an important role in the pathogenesis of primary lower extremity varicose veins.

The theory of detection and repair of cycle-slip by combination of BeiDou triple-frequency observations has been described. The optimization principles of triple-frequency observations, and the threshold of cycle-slip, and the relationship between the STD and success rate of cycle-slip fixed have been discussed. In consideration of ionospheric delay, selecting the phase/pseudorange combination that is suitable for BeiDou triple-frequency and utilizing measured data to calculate the estimation of combined cycle-slip. Results show that the amount of STD of cycle-slip calculated by three-stage method is smaller than pseudorange/phase combination, ensuring the accuracy of cycle-slip detection and repair; and the workload of detection and repair of cycle-slip by three-stage method has been decreased compared with geometry-free phase combination.

BACKGROUND Varicose veins (VVs) have a substantial impact on patients' quality of life. OBJECTIVE The study aimed to retrospectively compare the short-term clinical outcomes of 2 treatment methods for VVs, namely high ligation and stripping (HL/S) of the great saphenous vein combined with foam sclerotherapy (FS), and FS alone. MATERIALS AND METHODS Totally, 180 patients with VVs were included and treated with FS alone or HL/S+FS. Assessments included the first injection efficacy, postoperative status, complications, operative time, and recovery time. A follow-up duration was performed. Patient satisfaction was also recorded. RESULTS No significant differences in the complete occlusion rate of the varicose tributaries, as well as in postoperative complications, were found between the treatment groups (p > 0.05). The complete occlusion rates of the varicose tributaries in the FS and HL/S+FS groups were 90% and 90%, respectively. Although mild phlebitis and local pigmentation were found in both groups, they disappeared during the follow-up period. Operative and recovery times were higher in the HL/S+FS group than in the FS group. CONCLUSION The HL/S+FS and FS alone showed equivalent efficacy for treating patients with VVs. Considering the increased operative and recovery times, FS alone is recommended to treat VVs in clinical practice.

Typical iliac vein compression syndrome (IVCS) is characterized by compression of left common iliac vein (LCIV) by the overlying right common iliac artery (RCIA). We described an underestimated type of IVCS with dual compression by right and left common iliac arteries (LCIA) simultaneously. Thirty-one patients with IVCS were retrospectively included. All patients received trans-catheter venography and computed tomography (CT) examinations for diagnosing and evaluating IVCS. Late venography and reconstructed CT were used for evaluating the anatomical relationship among LCIV, RCIA and LCIA. Imaging manifestations as well as demographic data were collected and evaluated by two experienced radiologists. Sole and dual compression were found in 32.3% (n = 10) and 67.7% (n = 21) of 31 patients respectively. No statistical differences existed between them in terms of age, gender, LCIV diameter at the maximum compression point, pressure gradient across stenosis, and the percentage of compression level. On CT and venography, sole compression was commonly presented with a longitudinal compression at the orifice of LCIV while dual compression was usually presented as two types: one had a lengthy stenosis along the upper side of LCIV and the other was manifested by a longitudinal compression near to the orifice of external iliac vein. The presence of dual compression seemed significantly correlated with the tortuous LCIA (p = 0.006). Left common iliac vein can be presented by dual compression. This type of compression has typical manifestations on late venography and CT.

The etiology of thoracic aortic aneurysm and dissection (TAAD) is complex and heterogeneous. Emerging evidence has demonstrated that genetic causes may be a consideration in early‑onset TAAD. Owing to overlapping clinical phenotypes and the genetic heterogeneity of TAAD, it is challenging for clinicians to make a molecular diagnosis of TAAD, particularly in those who present with non‑specific syndromic features. In order to identify the causative mutation in two young patients with acute type B aortic dissection without syndromic features, whole exome sequencing (WES) was performed in the present study. A missense mutation (c.G6953A:p.C2318Y) and a nonsense mutation (c.C4786T:p.R1596X) were identified in the fibrillin 1 gene in patients T287 and T267, respectively. The present study emphasized the necessity of genetic testing for young patients with type B aortic dissection. WES is a timely, robust and inexpensive technique for molecular diagnosis, particularly for TAAD caused by numerous genes. Genetic diagnosis of Marfan syndrome could aid in periodic surveillance, prophylactic surgical measures, and genetic counseling.

Recent advances in understanding the interaction between electricity and cells/biomolecules have generated great interest in developing biocompatible electrically conductive materials. In this study, we investigated the biocompatibility of a myo-inositol hexakisphosphate gelated polyaniline hydrogel using in vitro and in vivo experiments in a rat model. The polyaniline hydrogel was used to coat a polycaprolactone scaffold and was cultured with rat endothelial progenitor cells differentiated from rat adipose-derived stem cells. Compared with the control sample on a pristine polycaprolactone scaffold, the treated polyaniline hydrogel had the same non-poisonous/cytotoxicity grade, enhanced cell adhesion, and a higher cell proliferation/growth rate. In implant studies, the polyaniline hydrogel sample induced milder inflammatory responses than did the control at the same time points. Combining the advantages of a biocompatible hydrogel and an organic conductor, the inositol phosphate-gelated polyaniline hydrogel could be used in bioelectronics applications such as biosensors, neural probes, cell stimulators, medical electrodes, tissue engineering, and electro-controlled drug delivery.

Variation in intermediate water salinity in the South China Sea (SCS) between the 1960s and 1980s was studied using historical hydrographic data. The results demonstrate that the water was significantly fresher in the 1980s than in the 1960s, indicating that vertical mixing at intermediate water depth was reduced in the 1980s. This was partially because of the change of the SCS meridional overturning circulation (MOC) connecting local intermediate water with deep water. Data assimilation showed a 0.5 Sv (1 Sv=106 m3 /s) reduction in the strength of the MOC, which is about one third of the mean SCS MOC. Because the SCS MOC is linked to the Pacific Ocean, such an interdecadal variation in the intermediate water SCS may reflect anthropogenic climate change in the world ocean.

We study the cyclicity of period annuli of some reversible non-Hamiltonian quadratic systems under quadratic perturbations. In general, the first integral, which we study, is non-algebraic. Via estimating the number of zeros of the associated Abelian integral (first order Melnikov function), we show that the cyclicity is 2.

Quadratic perturbations of a class of quadratic reversible systems are studied. The associated systems can have at most four limit cycles in any compact region of the period annuli, and if four limit cycles exist, then their distribution is ( 3 , 1 ) . In other words, three of them are nested and surrounding one focus, the other limit cycle is surrounding the different focus.

In this paper we study hyperelliptic limit cycles of the Lienard systems where, respectively, fm(x) and gn(x) are polynomials of degree m and n, gn(0) = 0. We prove that, if m ≥ 5 and m + 1 < n < 2m, then there always exist Lienard systems of the above form such that they have a hyperelliptic limit cycle. This gives a positive answer to the open problem posed in the paper by Yu and Zhang (2011 J. Math. Anal. Appl. 376 535–9). By combining all the results obtained up to now, we in fact give a complete classification of the hyperelliptic limit cycles of the Lienard systems: Lienard systems of the above form have hyperelliptic limit cycles only in the following cases: (i) m = 2, 3 and m + 3 ≤ n; (ii) 4 ≤ m and m + 2 ≤ n.