Symbolic extended dynamic mode decomposition.

In this paper, we present a new method of performing extended dynamic mode decomposition (EDMD) on systems, which admit a symbolic representation. EDMD generates estimates of the Koopman operator, K, for a dynamical system by defining a dictionary of observables on the space and producing an estimate, Km, which is restricted to be invariant on the span of this dictionary. A central question for the EDMD is what should the dictionary be? We consider a class of chaotic dynamical systems with a known or estimable generating partition. For these systems, we construct an effective dictionary from indicators of the "cylinder sets," which arise in defining the "symbolic system" from the generating partition. We prove strong operator topology convergence for both the projection onto the span of our dictionary and for Km. We also prove practical finite-step estimation bounds for the projection and Km as well. Finally, we demonstrate some numerical results on eigenspectrum estimation and forecasting applied to the dyadic map and the logistic map.

LncRNA SNHG15 relieves hyperglycemia-induced endothelial dysfunction via increased ubiquitination of thioredoxin-interacting protein.

Numerous studies have revealed that hyperglycemia is a pivotal driver of diabetic vascular complications. However, the mechanisms of hyperglycemia-induced endothelial dysfunction in diabetes remain incompletely understood. This study aims to expound on the underlying mechanism of the endothelial dysfunction induced by hyperglycemia from the perspective of long non-coding RNAs (lncRNA). In this study, a downregulation of SNHG15 was observed in the ischemic hind limb of diabetic mice and high glucose (HG)-treated HUVECs. Functionally, the overexpression of SNHG15 promoted cell proliferation, migration, and tube formation, and suppressed cell apoptosis in HG-treated HUVECs. Mechanistically, SNHG15 reduced thioredoxin-interacting protein (TXNIP) expression by enhancing ITCH-mediated ubiquitination of TXNIP. TXNIP overexpression abrogated the protective effect of lncRNA SNHG15 overexpression on HG-induced endothelial dysfunction. The following experiment further confirmed that SNHG15 overexpression promoted angiogenesis of the ischemic hind limb in diabetic mice. In conclusion, SNHG15 is a novel protector for hyperglycemia-induced endothelial dysfunction via decreasing TXNIP expression.

Experimental Analysis of the Quality of Needle-Assisted Fenestration in Aortic Stent-Grafts and the Differences Between Gradual and Rapid Balloon Dilation.

Purpose: To report the findings of an in vitro experiment to evaluate the quality of needle fenestrations dilated by different size balloons in various stent-grafts and to investigate the differences between gradual and rapid dilation. Materials and Methods: Fenestrations were made using an 18-G needle in 5 different polyester or expanded polytetrafluoroethylene (ePTFE) stent-grafts: Relay, Valiant, Hercules, TAG, and Ankura. Each stent-graft received 2 groups of fenestrations: one was followed by gradual sequential dilation (4-, 6-, 8-, and 10-mm balloons) and the other by rapid dilation (4- and 10-mm balloons). The pressure was increased to 10 atmospheres or until the balloon was fully inflated with no waist. Quantitative and qualitative evaluations, including fenestration diameter, area, shape, and margins were conducted using light microscopy and scanning electron microscopy. Results: Relay had the strongest resistance to dilation and Ankura the slightest. The maximum length and area of holes expanded as the balloon diameter increased. The fenestrations in polyester devices were mostly elliptical or slit-like, with limited tears but extensive fibers visible in the margin, while ePTFE stent-grafts showed larger fenestration areas with clearer margins. Ankura showed the best quality of fenestrations, which were always circular or square without fabric tears, while the holes in the TAG were square or elliptical but sometimes had a slit after large balloon dilation (≥6 mm). The Relay, Valiant, Hercules, and Ankura devices showed no difference in maximum diameter, fenestration area, or scores of shape and margin (p>0.05). Rapid dilation in the TAG increased the rate of uncontrolled fabric tear, resulting in a larger final diameter (12.90 vs 10.82 mm, p=0.047), smaller area (30.46 vs 41.09 mm2, p=0.028), worse shape (0.75 vs 1.20, p=0.268), and worse margin (0.40 vs 1.00, p=0.174). Though the decreased fenestration shape and margin scores did not reach statistical significance, the trend for decline was more obvious than with the other devices. Conclusion: Materials and structures of the stent-grafts determine the quality of fenestrations dilated by different size balloons. The use of sequential vs rapid balloon dilation is also crucial for fashioning high-quality fenestrations and should be selected judiciously.

Long-term Results of Thoracic Endovascular Aortic Repair for Type B Aortic Dissection and Risk Factors for Survival.

Purpose: To compare characteristics of acute, subacute, and chronic type B aortic dissection and their influence on long-term results of thoracic endovascular aortic repair (TEVAR). Materials and Methods: In a single-center, retrospective cohort study, 314 patients (median age 52 years; 244 men) with acute (n=165), subacute (n=115), or chronic (n=34) type B aortic dissection underwent TEVAR between January 2009 and December 2013. Patient demographics, risk factors, and imaging characteristics were compared among the groups. Univariable and multivariable Cox regression analyses were performed to identify any factors influencing survival. Results: The acute and subacute patients exhibited more complications at presentation than chronic patients. However, the chronic patients exhibited more aneurysmal dilatation (p<0.001) and true lumen collapse (p<0.001). Over a mean follow-up of 68.1±22.9 months (range 2-108), subacute patients showed a lower reintervention rate (3.6% vs 12.1% vs 12.1%, p=0.045), a lower major complication rate (14.4% vs 33.1% vs 27.3%, p=0.002), and better cumulative overall survival (p=0.03) than the acute and chronic groups, respectively. Furthermore, acute patients developed more stent-graft-induced distal erosion (p=0.017) and retrograde type A dissection (RTAD) (p=0.036), whereas chronic patients had less aortic remodeling in the stented segment (p<0.001), distal thoracic aorta (p<0.001), and abdominal aorta (p=0.047). Finally, multivariable analysis demonstrated age >52 years, visceral malperfusion, and RTAD as independent factors influencing overall survival; aneurysmal dilatation, rupture/impending rupture, and RTAD were independent factors influencing aorta-specific survival. Conclusion: Acute and subacute patients had increased risks of rupture and complications at presentation, whereas chronic patients had increased risks for aneurysmal dilatation. From a long-term perspective, the subacute phase might be an optimal time for TEVAR in cases of type B aortic dissection that do not need emergent interventions. The risk factors influencing survival should be identified, carefully managed, and possibly prevented.

Favourable Outcomes of Endovascular Total Aortic Arch Repair Via Needle Based In Situ Fenestration at a Mean Follow-Up of 5.4 Months.

OBJECTIVES: Endovascular repair of aortic arch pathologies remains challenging. Recently, needle based in situ fenestration (ISF) has shown great potential in endovascular total aortic arch repair (ETAAR). This study aimed to evaluate the feasibility, effectiveness, and safety of ETAAR via needle based ISF, and to present initial experience with this technique. DESIGN AND METHODS: Patients who met the inclusion criteria were enrolled in this prospective study. The supra-arch branches were manually punctured in a retrograde manner using liver biopsy needles (18 gauge/30 cm) in the left common carotid artery (LCCA) and brachiocephalic trunk (BCT), and endo-puncture system or aspiration biopsy needles (21-gauge) in the left subclavian artery (LSA). All the branches were revascularised with bridge stents. Routine follow-up occurred at 1, 3, 6, and 12 months post surgery. RESULTS: Ten patients with arch pathologies underwent ETAAR. Revascularisation of three branches was successfully performed in eight patients, but attempts to create ISF in LSA were unsuccessful in two patients because of tortuosity and sharp angle. The time taken to establish ISF in LCCA and BCT was 100.4s and 489.6s, respectively. Bilateral regional cerebral oxygen saturation (RCOS) decreased after the arch endograft deployment (both, p < .001) and recovered to the pre-operative level once both carotid arteries were reconstructed (left, p = .0856; right, p = .6). The right RCOS was higher with the beneficial effect of extracorporeal circulation (after cTAGs deployment, p < .001; after LCCA revascularised, p = .0148) during the ischaemic period. In one case, the left iliac artery ruptured, but no ISF related or neurological complications occurred. An early follow-up (mean 5.44 months) CTA and ultrasound confirmed patency of all the branch grafts without any endoleak or migration CONCLUSIONS: This study demonstrated that ETAAR via needle based ISF, making full use of off the shelf devices and techniques, can be successfully performed in aortic arch pathologies with a favourable early outcome.

Advanced Glycation End-Products Downregulate HoxA9EC through Activation of Nuclear Factor Kappa B by Reciprocal Interaction.

Advanced glycation end-products (AGEs) have been recognized as an important pathophysiological mechanism in endothelial dysfunction during diabetic atherogenesis. Homeobox (Hox) genes have been identified as playing a regulatory role in the adult cardiovascular system. Regulation of HoxA9EC is involved in diabetic endothelial dysfunction, but the mechanism of HoxA9EC regulation has remained undefined. Here, we sought to investigate how HoxA9EC is regulated in AGE-induced endothelial dysfunction and to explore the mechanism involved. We used human umbilical venous endothelial cells (HUVECs) cocultured with AGEs, and examined endothelial nitric oxide synthase (eNOS) activation, nitric oxide (NO) release, cell migration, and the expression of HoxA9EC and nuclear factor kappa B (NF-κB). AGEs suppressed eNOS activation, NO release, and the migration of HUVECs. Knockout of HoxA9EC also reduced eNOS activation, NO release, and the migration of HUVECs, and the enhancement of HoxA9EC improved the function of HUVECs. Furthermore, AGEs downregulated HoxA9EC expression and activated NF-κB, and the depression of HoxA9EC was significantly attenuated by the NF-κB inhibitor. On the other hand, knockout of HoxA9EC activated NF-κB and the enhancement of HoxA9EC suppressed NF-κB activation. In conclusion, AGEs could induce endothelial dysfunction through NF-κB-dependent HoxA9EC downregulation by reciprocal interaction, and the enhancement of HoxA9EC expression could attenuate the impairment.

Morphologic findings and management strategy of spontaneous isolated dissection of the celiac artery.

OBJECTIVE: We report the morphologic findings and treatment of spontaneous isolated dissection of the celiac artery (SIDCA). METHODS: Twenty-three patients with SIDCA presenting between January 2009 and December 2014 were enrolled in this retrospective study. The demographic data, clinical features, morphologic findings, treatment modalities, and follow-up results of these patients were reviewed. We proposed a morphologic classification for SIDCA similar to that of spontaneous isolated dissection of the superior mesenteric artery. RESULTS: Initially, 11 patients were treated endovascularly, and 12 were treated medically. Four patients treated medically had an aggravation of the dissection and needed endovascular salvage. All patients recovered successfully. None of the patients developed abdominal pain, required reintervention, or died. In the medically treated group, the false lumen was completely thrombosed and absorbed in 4 patients, partially thrombosed in 2, and patent in 2. All stents were patent with the false lumen completely thrombosed and absorbed in the endovascular group. CONCLUSIONS: SIDCA can be treated medically in stable patients but requires intensive follow-up. Endovascular therapy can be applied in high-risk patients with recurrent symptoms, visceral malperfusion, or aneurysm. Open surgery should be considered if endovascular repair is not suitable or has failed. The short-term results of endovascular management are encouraging but further evaluation with long-term follow-up is necessary.

Endovascular treatment of isolated abdominal aortic dissection and postoperative aortic remodeling.

OBJECTIVE: We report our experience of endovascular management and postoperative aortic remodeling of all types of isolated abdominal aortic dissection (IAAD). METHODS: This was retrospective study of 28 IAAD patients treated by endovascular means in our department between January 2007 and July 2013. We reviewed the risk factors, clinical features, computed tomography images, follow-up results, and aortic remodeling of these IAAD patients and propose a new morphologic classification into three types-supraceliac, paravisceral, and infrarenal-according to the location of the primary entry site. RESULTS: There were four supraceliac IAADs, one paravisceral IAAD, and 23 infrarenal IAADs in our case series. Suprarenal (supraceliac + paravisceral) IAAD patients were relatively younger than infrarenal patients (45.2 ± 8.6 years vs 60.6 ± 15.5 years; P < .05). No difference was observed between suprarenal and infrarenal IAADs with respect to true lumen, false lumen, and dissection length on imaging (P > .05). All patients received endovascular treatment. The primary technical success rate was 100%. During a follow-up of 35.7 ± 19.9 months, only one infrarenal patient needed an endovascular reintervention. All patients with supraceliac or infrarenal IAADs were alive at the time of follow-up; however, a paravisceral patient died of a dissecting abdominal aortic aneurysm rupture 21 months after endovascular treatment. In the suprarenal and infrarenal groups, endovascular treatment was associated with a significant decrease in the false lumen size and increase in the true lumen size (P < .05). The maximum abdominal aorta diameter decreased after endovascular treatment in both groups but was statistically significant only in the infrarenal group (P < .05). CONCLUSIONS: IAAD is a rare vascular disease. We propose it should be categorized as supraceliac, paravisceral, and infrarenal IAAD according to the location of the primary entry site. Endovascular treatment for supraceliac and infrarenal IAADs is a safe method with a high technical success rate and promising aortic remodeling, whereas endovascular treatment for paravisceral IAADs remains difficult.

Stability and ergodicity of moon billiards.

We construct a two-parameter family of moon-shaped billiard tables with boundary made of two circular arcs. These tables fail the defocusing mechanism and other known mechanisms that guarantee ergodicity and hyperbolicity. We analytically study the stability of some periodic orbits and prove there is a class of billiards in this family with elliptic periodic orbits. These moon billiards can be viewed as generalization of annular billiards, which all have Kolmogorov-Arnold-Moser islands. However, the novelty of this paper is that by varying the parameters, we numerically observe a subclass of moon-shaped billiards with a single ergodic component.

Management strategy for spontaneous isolated dissection of the superior mesenteric artery based on morphologic classification.

OBJECTIVE: To explore a therapy strategy for the spontaneous isolated dissection of the superior mesenteric artery (SIDSMA) based on morphologic classification. METHODS: Forty-two symptomatic patients with SIDSMA presenting with abdominal pain between January 2007 and December 2012 were enrolled in this retrospective study. We proposed a new morphologic classification with subtypes depending on the patency of the true lumen and reviewed the patients' clinical features, risk factors, computed tomography images (morphologic classification, location of entry site, dissection length, and true lumen residual diameter), treatment modalities, and follow-up results. RESULTS: Twenty-four patients received only observation treatment, seven received open surgery, and 11 received endovascular therapy. True lumen residual diameter in the observation group (46.6%) was statistically better than that in the surgery group (0%) and the endovascular group (18.3%) (P < .05). There was clinical progression in three and imaging progression in seven of the observation group, of which two patients received endovascular treatment and one patient died of bowel infarction. There were two clinical progressions and one imaging progression in the surgery group, of which two patients received additional surgery and one patient died of bowel infarction. The endovascular group obtained encouraging results with no progressions or complications. CONCLUSIONS: Symptomatic patients with SIDSMA are at risk of progression. We suggested a morphologic classification to guide the treatment. We recommend observation treatment with close follow-up for patients with patent true lumen flow and endovascular intervention for high-risk patients with true lumen stenosis or occlusion. Surgery is indicated for patients with suspected bowel infarction or arterial rupture.