Superficial femoral artery access for endovascular aortic repair.

OBJECTIVE: The majority of endovascular aneurysm repair procedures are performed through the common femoral artery (CFA). Arterial access is gained by surgical cutdown or percutaneous approach. The surgical approach has a relatively high local complication rate. We describe superficial femoral artery (SFA) access as an alternative to CFA exposure to minimize wound complications and to facilitate swift recovery. METHODS: A single-center, retrospective study of patients undergoing endovascular aneurysm repair between 2014 and 2016 was performed; 195 patients undergoing 215 procedures were included, 114 with CFA cutdown, 87 with SFA cutdown, and 14 with combined SFA and CFA procedures. Epidemiologic parameters, risk factors, procedural details, operative and postoperative complications, and time to discharge were assessed. Independent samples two-sided t-test and χ2 test were used to compare the SFA and CFA. A P value < .05 was considered statistically significant. A multivariate adjusted model confirmed the results. The proximal SFA is assessed by computed tomography angiography for patency and suitability. The minimal SFA diameter of 6 mm was determined for considering SFA access. Through a longitudinal incision at the upper thigh, the SFA is exposed and catheterized. Devices are inserted sheathless and replaced by small-diameter sheaths (14F-16F). Patients undergo peripheral vascular examination before and after the procedure. RESULTS: Age, sex, and risk factor distribution were similar in both groups. Aneurysm size and device diameters were also similar. There were 12.1% of cases that were not suitable for the SFA approach. Access-related bleeding (0.7% SFA, 7% CFA; P = .004), ischemia (0.7% SFA, 7.6% CFA; P = .002), and venous injury (0% SFA, 1.3% CFA; P = .102) were minimized with SFA exposure. This led to almost 50% decrease in patients requiring additional arterial reconstruction during the procedure (6.5% SFA, 12.8% CFA; P = .059). SFA cutdown was also associated with lower wound complication rate (infection, seroma, and hematoma; 13.2% SFA, 34.9% CFA; P = .000). Neuropathy (mostly sensory) was higher with SFA exposure (13.8% SFA, 5.2% CFA; P = .008). The patients' recovery was faster in the SFA group, resulting in 14.3% reduction of hospital stay after the procedure (P = .005). Secondary access-related procedures were also lower in the SFA group (2.2% SFA, 8.7% CFA; P = .045). CONCLUSIONS: The SFA approach is easier to perform and has a lower complication rate compared with the CFA approach. During the procedure, there is no dissection or damage to arterial branches, especially to the deep femoral artery. The SFA approach has a low complication rate and can be an alternative to percutaneous access when it is unsuitable.

Retrograde Femoral Artery Stent-Graft Implantation for Treatment of Access-site Bleeding Following Transcatheter Aortic Valve Implantation.

BACKGROUND: Access-site bleeding is a common complication of transfemoral transcatheter aortic valve implantation (TAVI). Percutaneous stent-graft implantation within the femoral artery may achieve hemostasis and avert the need for more invasive surgical vascular repair; however, failure to advance a guidewire antegradely via the injured vessel may preclude stent delivery. While retrograde stent-graft delivery from the distal vasculature may potentially enable percutaneous control of bleeding, this approach has not been reported. OBJECTIVES: To assess the feasibility of a retrograde approach for stent-graft implantation in the treatment of access-site bleeding following transfemoral TAVI. METHODS: A prospective TAVI registry was analyzed. Of 349 patients who underwent TAVI, transfemoral access was used in 332 (95%). Access-site injury requiring stent-graft implantation occurred in 56 (17%). In four patients (7%), antegrade wiring across the site of vascular injury was not possible and a retrograde approach for stent delivery was used. RESULTS: Distal vascular access was achieved via the superficial femoral or profunda artery. Retrograde advancement of a polymer-coated 0.035" wire to the abdominal aorta, followed by stent-graft delivery to the common femoral artery, achieved hemostasis in all cases. During a median (interquartile range) follow-up period of 198 (618) days (range 46-2455) there were no deaths and no patient required additional vascular interventions. CONCLUSIONS: A retrograde approach for stent-graft delivery is feasible and allows percutaneous treatment of a common femoral artery injury following TAVI in patients who are not suitable for the conventional antegrade approach.

Carotid Endarterectomy in a Patient With Type 2 Myocardial Infarction During Preparation for Surgery: A Case Report.

We present a patient who was admitted for carotid endarterectomy due to tight carotid stenosis and recent amaurosis fugax. His medical history included significant coronary artery disease with stable angina pectoris, hypertension with wide pulse pressure, chronic renal failure, and anemia. During preparation for surgery, the patient developed type 2 myocardial infarction with prolonged chest pain, ST depressions on electrocardiogram, and significant troponin elevations. The patient posed a serious clinical dilemma whether to continue with surgery despite the type 2 myocardial infarction or postpone the surgery. We discuss the diagnostic tests and the decision-making processes that guided us in the preoperative period.

Monoubiquitylation of alpha-synuclein by seven in absentia homolog (SIAH) promotes its aggregation in dopaminergic cells.

alpha-Synuclein plays a major role in Parkinson disease. Unraveling the mechanisms of alpha-synuclein aggregation is essential to understand the formation of Lewy bodies and their involvement in dopaminergic cell death. alpha-Synuclein is ubiquitylated in Lewy bodies, but the role of alpha-synuclein ubiquitylation has been mysterious. We now report that the ubiquitin-protein isopeptide ligase seven in absentia homolog (SIAH) directly interacts with and monoubiquitylates alpha-synuclein and promotes its aggregation in vitro and in vivo, which is toxic to cells. Mass spectrometry analysis demonstrates that SIAH monoubiquitylates alpha-synuclein at lysines 12, 21, and 23, which were previously shown to be ubiquitylated in Lewy bodies. SIAH ubiquitylates lysines 10, 34, 43, and 96 as well. Suppression of SIAH expression by short hairpin RNA to SIAH-1 and SIAH-2 abolished alpha-synuclein monoubiquitylation in dopaminergic cells, indicating that endogenous SIAH ubiquitylates alpha-synuclein. Moreover, SIAH co-immunoprecipitated with alpha-synuclein from brain extracts. Inhibition of proteasomal, lysosomal, and autophagic pathways, as well as overexpression of a ubiquitin mutant less prone to deubiquitylation, G76A, increased monoubiquitylation of alpha-synuclein by SIAH. Monoubiquitylation increased the aggregation of alpha-synuclein in vitro. At the electron microscopy level, monoubiquitylated alpha-synuclein promoted the formation of massive amounts of amorphous aggregates. Monoubiquitylation also increased alpha-synuclein aggregation in vivo as observed by increased formation of alpha-synuclein inclusion bodies within dopaminergic cells. These inclusions are toxic to cells, and their formation was prevented when endogenous SIAH expression was suppressed. Our data suggest that monoubiquitylation represents a possible trigger event for alpha-synuclein aggregation and Lewy body formation.

Phosphorylation of Parkin by the cyclin-dependent kinase 5 at the linker region modulates its ubiquitin-ligase activity and aggregation.

Mutations in Parkin are responsible for a large percentage of autosomal recessive juvenile parkinsonism cases. Parkin displays ubiquitin-ligase activity and protects against cell death promoted by several insults. Therefore, regulation of Parkin activities is important for understanding the dopaminergic cell death observed in Parkinson disease. We now report that cyclin-dependent kinase 5 (Cdk5) phosphorylates Parkin both in vitro and in vivo. We found that highly specific Cdk5 inhibitors and a dominant negative Cdk5 construct inhibited Parkin phosphorylation, suggesting that a significant portion of Parkin is phosphorylated by Cdk5. Parkin interacts with Cdk5 as observed by co-immunoprecipitation experiments of transfected cells and rat brains. Phosphorylation by Cdk5 decreased the auto-ubiquitylation of Parkin both in vitro and in vivo. We identified Ser-131 located at the linker region of Parkin as the major Cdk5 phosphorylation site. The Cdk5 phosphorylation-deficient S131A Parkin mutant displayed a higher auto-ubiquitylation level and increased ubiquitylation activity toward its substrates synphilin-1 and p38. Additionally, the S131A Parkin mutant more significantly accumulated into inclusions in human dopaminergic cells when compared with the wild-type Parkin. Furthermore, S131A Parkin mutant increased the formation of synphilin-1/alpha-synuclein inclusions, suggesting that the levels of Parkin phosphorylation and ubiquitylation may modulate the formation of inclusion bodies relevant to the disease. The data indicate that Cdk5 is a new regulator of the Parkin ubiquitin-ligase activity and modulates its ability to accumulate into and modify inclusions. Phosphorylation by Cdk5 may contribute to the accumulation of toxic Parkin substrates and decrease the ability of dopaminergic cells to cope with toxic insults in Parkinson disease.

Synphilin-1A: an aggregation-prone isoform of synphilin-1 that causes neuronal death and is present in aggregates from alpha-synucleinopathy patients.

alpha-Synucleinopathies are a group of neurological disorders characterized by the presence of intracellular inclusion bodies containing alpha-synuclein. We previously demonstrated that synphilin-1 interacts with alpha-synuclein, implying a role in Parkinson's disease. We now report the identification and characterization of synphilin-1A, an isoform of synphilin-1, which has enhanced aggregatory properties and causes neurotoxicity. The two transcripts encoding synphilin-1A and synphilin-1 originate from the SNCAIP gene but differ in both their exon organization and initial reading frames used for translation. Synphilin-1A binds to alpha-synuclein and induces the formation of intracellular aggregates in human embryonic kidney 293 cells, primary neuronal cultures, and human dopaminergic cells. Overexpression of synphilin-1A in neurons results in striking cellular toxicity that is attenuated by the formation of synphilin-1A inclusions, which recruit alpha-synuclein. Synphilin-1A is present in Lewy bodies of patients with Parkinson's disease and Diffuse Lewy Body disease, and is observed in detergent-insoluble fractions of brain protein samples obtained from Diffuse Lewy Body disease patients. These findings suggest that synphilin-1A may contribute to neuronal degeneration in alpha-synucleinopathies and also provide important insights into the role of inclusion bodies in neurodegenerative disorders.

Glycogen synthase kinase 3beta modulates synphilin-1 ubiquitylation and cellular inclusion formation by SIAH: implications for proteasomal function and Lewy body formation.

alpha-Synuclein is known to play a major role in the pathogenesis of Parkinson disease. We previously identified synphilin-1 as an alpha-synuclein-interacting protein and more recently found that synphilin-1 also interacts with the E3 ubiquitin ligases SIAH-1 and SIAH-2. SIAH proteins ubiquitylate synphilin-1 and promote its degradation through the ubiquitin proteasome system. Inability of the proteasome to degrade synphilin-1 promotes the formation of ubiquitylated inclusion bodies. We now show that synphilin-1 is phosphorylated by GSK3beta within amino acids 550-659 and that this phosphorylation is significantly decreased by pharmacological inhibition of GSK3beta and suppression of GSK3beta expression by small interfering RNA duplex. Mutation analysis showed that Ser556 is a major GSK3beta phosphorylation site in synphilin-1. GSK3beta co-immunoprecipitated with synphilin-1, and protein 14-3-3, an activator of GSK3beta activity, increased synphilin-1 phosphorylation. GSK3beta decreased the in vitro and in vivo ubiquitylation of synphilin-1 as well as its degradation promoted by SIAH. Pharmacological inhibition and small interfering RNA suppression of GSK3beta greatly increased ubiquitylation and inclusion body formation by SIAH. Additionally, synphilin-1 S556A mutant, which is less phosphorylated by GSK3beta, formed more inclusion bodies than wild type synphilin-1. Inhibition of GSK3beta in primary neuronal cultures decreased the levels of endogenous synphilin-1, indicating that synphilin-1 is a physiologic substrate of GSK3beta. Using GFPu as a reporter to measure proteasome function in vivo, we found that synphilin-1 S556A is more efficient in inhibiting the proteasome than wild type synphilin-1, raising the possibility that the degree of synphilin-1 phosphorylation may regulate the proteasome function. Activation of GSK3beta during endoplasmic reticulum stress and the specific phosphorylation of synphilin-1 by GSK3beta place synphilin-1 as a possible mediator of endoplasmic reticulum stress and proteasomal dysfunction observed in Parkinson disease.

Ubiquitylation of synphilin-1 and alpha-synuclein by SIAH and its presence in cellular inclusions and Lewy bodies imply a role in Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disease characterized by Lewy body formation and death of dopaminergic neurons. Mutations in alpha-synuclein and parkin cause familial forms of PD. Synphilin-1 was shown to interact with alpha-synuclein and to promote the formation of cytosolic inclusions. We now report that synphilin-1 interacts with the E3 ubiquitin-ligases SIAH-1 and SIAH-2. SIAH proteins ubiquitylate synphilin-1 both in vitro and in vivo, promoting its degradation by the ubiquitin-proteasome system. Inability of the proteasome to degrade synphilin-1/SIAH complex leads to a robust formation of ubiquitylated cytosolic inclusions. Ubiquitylation is required for inclusion formation, because a catalytically inactive mutant of SIAH-1, which still binds to synphilin-1, fails to promote inclusions. Like synphilin-1, alpha-synuclein associates with SIAH in intact cells, but the interaction with SIAH-2 was much stronger that with SIAH-1. In vitro experiments show that SIAH-2 monoubiquitylates alpha-synuclein. Further evidence that SIAH proteins may play a role in inclusion formation comes from the demonstration of SIAH immunoreactivity in Lewy bodies of PD patients.