The combined use of thoracic and abdominal aortic stent grafts for endovascular repair of wide neck abdominal aortic aneurysms in high risk patients.

INTRODUCTION: Treatment of abdominal aortic aneurysms (AAA) with large (28 mm to 34 mm) and wide diameter (> 35 mm) necks remains a challenge in patients who are high-risk candidates for open repair. While several case reports describe the use of a thoracic stent graft in conjunction with a traditional modular bifurcated stent graft, most patients do not have the aortic length to accommodate such a configuration. We present our experience utilizing a distal unibody bifurcated aortic stent graft (Endologix, Irvine, CA) in conjunction with a proximal thoracic aortic stent graft (Medtronic, Minneapolis, MN) to treat wide-necked non-ruptured AAAs in patients who were otherwise poor candidates for open or fenestrated repair. METHODS: A single center retrospective review of patients treated with a combination of a distal unibody bifurcated aortic stent graft and a proximal thoracic aortic stent graft extension from 2013 to 2019 was performed. Demographics, perioperative details and long-term outcomes were collected and summarized. Standard statistical methods were utilized. RESULTS: We identified 7 patients who underwent this procedure during the study interval. Of these, all 7 (100%) were male with an average age of 69.1 ± 5.1 years. Average Charlson Comorbidity Index was 5.0. Average pre-operative maximum aortic and neck diameters were 57.9 mm (± 5.8) and 37.4 mm (± 4.5) respectively. All patients underwent repair with a distal 28 mm diameter unibody bifurcated aortic stent graft and proximal extension with a thoracic aortic stent graft that ranged from 40 to 46 mm in diameter. Technical success was achieved in all 7 patients. There were no perioperative mortalities or aorta-related deaths. Follow up was a mean of 1.98 years with a mean survival of 4.75 years (± 0.86). One patient required an aneurysm-related intervention for a late type III endoleak. CONCLUSION: The combined use of thoracic and abdominal aortic stent grafts is a safe and effective endovascular method to treat high-risk surgical candidates with wide-necked AAAs.

Outcome of rectus femoris muscle flaps performed by vascular surgeons for the management of complex groin wounds after femoral artery reconstructions.

OBJECTIVE: Groin wound complications after femoral artery reconstructions are highly morbid and notoriously difficult to treat. Successful techniques include long-term antibiotic therapy, operative débridement, and muscle flap coverage. Historically, more complex muscle flap coverage, such as a rectus femoris muscle flap (RFF), has been performed by plastic and reconstructive surgeons. In this study, the experience of vascular surgeons performing RFF in the management of wound complications after femoral artery reconstructions is reported. METHODS: Clinical data between 2012 and 2018 were retrospectively analyzed. Data were summarized, and standard statistical analysis was performed. RESULTS: There were 23 patients who underwent 24 RFFs for coverage of complex groin wounds after femoral artery reconstructions. One of the 23 patients underwent bilateral RFFs. In this study cohort, patients had a median age of 67.5 years, and 79% (n = 19) were male. Median body mass index was 28.0 kg/m2, and 38% of patients were classified as obese on the basis of body mass index criteria. A history of tobacco use was present in 88%; however, only 29% were current smokers. Diabetes was present in 38% of patients and chronic kidney disease in 29%. Of the 24 RFFs, 14 (58%) were constructed in patients with reoperative groin surgery resulting in the need for muscle flap coverage. Femoral endarterectomy was the most common index procedure (46%), followed by infrainguinal leg bypass surgery (17%) and aortobifemoral bypass (17%). Grafts used during the original reconstruction included 12 bovine pericardial patches (50%), 6 Dacron grafts (25%), 4 PTFE grafts (17%), and 2 autogenous reconstructions (8%). Microbiology data identified 33% of patients (n = 8) to have gram-positive bacterial infections alone, 21% (n = 5) to have gram-negative infections alone, and 29% (n = 7) to have polymicrobial infections; 4 patients (13%) had negative intraoperative culture data. Median hospital stay after RFF was 8 days, and median follow-up time was 29.3 months. Major amputation was avoided in 20 of 24 limbs (83%) undergoing RFF. Eight patients underwent intentional graft or patch explantation (33%) before RFF, whereas 14 of the remaining 15 patients (93%) had successful salvage of the graft or patch after RFF. Two of the patients (13%) who underwent RFF with the intention of salvaging a prosthetic graft or patch required later graft excision. After RFF, 30-day and 1-year survival was 96% and 87%, respectively. CONCLUSIONS: RFF coverage of complex groin wounds after femoral artery reconstructions may safely be performed by vascular surgeons with excellent outcomes.

Outcomes of familial abdominal aortic aneurysm repair in the Vascular Quality Initiative.

OBJECTIVE: Recent investigations have reported increased rates of aneurysm-related complications after endovascular aneurysm repair (EVAR) in familial abdominal aortic aneurysm (fAAA) patients. The purpose of this study was to evaluate the outcomes of open aortic repair (OAR) and EVAR in sporadic AAA (spAAA) and fAAA patients in the Society for Vascular Surgery Vascular Quality Initiative. METHODS: This was a retrospective review of all AAA repairs in the Vascular Quality Initiative from 2003 to 2017. Patients' data were summarized, and standard statistical analysis was performed. Patients with known genetic syndromes and centers with long-term follow-up of <50% of patients were excluded. RESULTS: From 2003 to 2017, there were 1997 fAAA patients compared with 18,185 spAAA patients undergoing OAR and EVAR during the same study period. Compared with their spAAA counterparts, fAAA patients were younger (P < .001), were more likely to be living at home before surgery (P = .008), and demonstrated a lower incidence of coronary artery disease (P = .001) and hypertension (P = .039). Rates of smoking and end-stage renal disease did not differ between groups. However, fAAA patients were more likely to have aneurysmal degeneration of their iliac arteries (P < .001) and to undergo OAR (P < .001). When analyzing patients undergoing OAR, we found that fAAA patients were more likely to require concomitant renal bypass surgery (P = .012) but were extubated sooner (P = .005), received fewer blood transfusions (P < .001), and had a shorter length of stay (P = .018). Although individual complication rates did not differ between fAAA and spAAA groups after OAR, a composite end point of all early postoperative complications was decreased in fAAA patients (P = .020). When comparing fAAA and spAAA patients who underwent EVAR, we found a greater incidence of early lumbar branch endoleaks (type II) in fAAA patients; however, the rate of proximal type IA endoleaks (P = .279) and the rate of late reintervention for sac growth (P = .786), any endoleak (P = .439), or rupture (P = .649) did not differ between the groups. Whereas spAAA patients undergoing EVAR required longer postoperative intensive care unit stays (P < .001) and had a greater incidence of blood transfusions (P < .001), fAAA and spAAA patients had similar rates of postoperative complications (P = .510), 30-day mortality (P = .177), and long-term mortality (P = .259). CONCLUSIONS: This study shows that patients with a familial form of AAA do not have increased morbidity or mortality after AAA repair. Our findings suggest that EVAR and OAR are both safe and effective for fAAA patients. Further studies with longer follow-up are needed to best care for this unique cohort of patients.

Outcomes of endovascular treatments for in-stent restenosis in patients with mesenteric atherosclerotic disease.

OBJECTIVE: Mesenteric angioplasty and stenting (MAS) has surpassed open revascularization as the treatment of choice for mesenteric ischemia. Despite the lower perioperative mortality associated with MAS, the need for reintervention is not infrequent. The purpose of this study was to review the outcomes of patients treated for mesenteric artery in-stent restenosis (MAISR). METHODS: Clinical data from a single center between 2004 and 2017 were retrospectively analyzed. Standard statistical analysis including Kaplan-Meier estimate for time-dependent outcomes, χ2 test for categorical variables, and two-sample t-test for continuous variables was performed. Primary end points included stent patency and reintervention rate. Secondary end points included mortality and morbidity. RESULTS: During the study period, 91 patients underwent primary MAS. In total, 113 mesenteric vessels were treated with 20 covered stents and 93 bare-metal stents. Overall primary patency was 69% at 2 years. At 2 years, primary patency was 83% for covered stents compared with 65% for bare-metal stents (P = .17). Of these 91 primary MAS patients, 27 (30%) were treated for MAISR (32 vessels). Two covered stent patients developed significant restenosis (11%) compared with 25 (34%) bare-metal stent patients (P = .02). The mean age of patients requiring reintervention was 69 years (36% male), with the majority having a history of tobacco use (85%), hypertension (75%), and hyperlipidemia (78%). Fourteen reintervention patients (52%) presented with recurrent symptoms, 10 (37%) had asymptomatic restenosis, and 3 (11%) developed intestinal ischemia. Twelve patients (44%) underwent reintervention with balloon angioplasty alone and 15 (56%) underwent repeated stent placement. Of the 15 patients who had repeated stent placement, 7 patients had covered stents placed. The 30-day mortality rate after reintervention for mesenteric stent restenosis was 0%. Postoperative complications occurred in 15% of patients (myocardial infarction, 4%; reversible kidney injury, 4%; and bowel ischemia requiring surgical exploration, 7%). There was no difference in the perioperative morbidity in comparing symptomatic and asymptomatic patients undergoing reintervention. Mean follow-up after mesenteric reintervention was 31 months, with one-third of patients (n = 9) requiring another reintervention because of either recurrence of symptoms or asymptomatic high-grade restenosis. Assisted primary patency at 2 years was 92% after reintervention with balloon angioplasty and 87% for repeated stent placement, with no statistically significant difference between the groups (P = .66). CONCLUSIONS: Treatment of MAISR is associated with low mortality and acceptable morbidity. The initial use of covered stents may reduce the need for reintervention.

Advanced Endovascular Approaches in the Management of Challenging Proximal Aortic Neck Anatomy: Traditional Endografts and the Snorkel Technique.

Advances in endovascular technology, and access to this technology, have significantly changed the field of vascular surgery. Nowhere is this more apparent than in the treatment of abdominal aortic aneurysms (AAAs), in which endovascular aneurysm repair (EVAR) has replaced the traditional open surgical approach in patients with suitable anatomy. However, approximately one-third of patients presenting with AAAs are deemed ineligible for standard EVAR because of anatomic constraints, the majority of which involve the proximal aneurysmal neck. To overcome these challenges, a bevy of endovascular approaches have been developed to either enhance stent graft fixation at the proximal neck or extend the proximal landing zone to allow adequate apposition to the aortic wall and thus aneurysm exclusion. This article is composed of two sections that together address new endovascular approaches for treating aortic aneurysms with difficult proximal neck anatomy. The first section will explore advancements in the traditional EVAR approach for hostile neck anatomy that maximize the use of the native proximal landing zone; the second section will discuss a technique that was developed to extend the native proximal landing zone and maintain perfusion to vital aortic branches using common, off-the-shelf components: the snorkel technique. While the techniques presented differ in terms of approach, the available clinical data, albeit limited, support the notion that they may both have roles in the treatment algorithm for patients with challenging proximal neck anatomy.

Fetal brain mTOR signaling activation in tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is characterized by developmental malformations of the cerebral cortex known as tubers, comprised of cells that exhibit enhanced mammalian target of rapamycin (mTOR) signaling. To date, there are no reports of mTORC1 and mTORC2 activation in fetal tubers or in neural progenitor cells lacking Tsc2. We demonstrate mTORC1 activation by immunohistochemical detection of substrates phospho-p70S6K1 (T389) and phospho-S6 (S235/236), and mTORC2 activation by substrates phospho-PKCα (S657), phospho-Akt (Ser473), and phospho-SGK1 (S422) in fetal tubers. Then, we show that Tsc2 shRNA knockdown (KD) in mouse neural progenitor cells (mNPCs) in vitro results in enhanced mTORC1 (phospho-S6, phospho-4E-BP1) and mTORC2 (phospho-Akt and phospho-NDRG1) signaling, as well as a doubling of cell size that is rescued by rapamycin, an mTORC1 inhibitor. Tsc2 KD in vivo in the fetal mouse brain by in utero electroporation causes disorganized cortical lamination and increased cell volume that is prevented with rapamycin. We demonstrate for the first time that mTORC1 and mTORC2 signaling is activated in fetal tubers and in mNPCs following Tsc2 KD. These results suggest that inhibition of mTOR pathway signaling during embryogenesis could prevent abnormal brain development in TSC.

Results of carotid angioplasty and stenting are equivalent for critical versus high-grade lesions in patients deemed high risk for carotid endarterectomy.

BACKGROUND: To examine outcomes of carotid angioplasty and stenting (CAS) in patients with critical carotid stenosis who are deemed high risk for carotid endarterectomy. METHODS: Medical records were retrospectively analyzed for patients undergoing CAS between September 2002 and March 2011 at a single institution. Patients were classified as having either critical (≥ 90%) or high-grade (70%-89%) carotid stenosis based on angiography. The primary composite end point was stroke, myocardial infarction, or death from any cause during the periprocedural period or any ipsilateral stroke during the follow-up period. RESULTS: A total of 245 patients underwent 257 CAS procedures during the study period. Fifty-one percentage (n = 130) of cases involved critical stenosis (66.2% male; mean age, 71 ± 10 y), with the remaining group (n = 127) involving high-grade stenosis (67.7% male; mean age, 71 ± 9 y). Symptomatic carotid disease was present in 25% of the critical stenosis and 31% of the high-grade stenosis groups (P = 0.33). Chronic obstructive pulmonary disease was more commonly found in the high-grade stenosis group (20% versus 8%, P = 0.01). No difference was observed between the groups relative to other baseline demographic characteristics, presence of contralateral carotid occlusion, stent diameter or length, maximum balloon diameter or length, use of embolic protection device, or procedural duration. Technical success was achieved in all cases. There was no difference in the need to predilate before the introduction of the filter or stent based on the degree of stenosis. We found no difference in the primary composite end point between the high-grade or critical stenosis groups (7.1% versus 7.7%, P = 0.74), or there were no differences between the individual components of the composite end point. Mid-term survival was similar between the two groups at a mean follow-up period of 2.4 y. CONCLUSIONS: Despite concerns regarding the potential for increased neurologic complications, our data demonstrate that patients with high-grade and critical stenosis are able to safely undergo CAS and achieve similar periprocedural outcomes and mid-term prognosis.

Rapamycin prevents seizures after depletion of STRADA in a rare neurodevelopmental disorder.

A rare neurodevelopmental disorder in the Old Order Mennonite population called PMSE (polyhydramnios, megalencephaly, and symptomatic epilepsy syndrome; also called Pretzel syndrome) is characterized by infantile-onset epilepsy, neurocognitive delay, craniofacial dysmorphism, and histopathological evidence of heterotopic neurons in subcortical white matter and subependymal regions. PMSE is caused by a homozygous deletion of exons 9 to 13 of the LYK5/STRADA gene, which encodes the pseudokinase STRADA, an upstream inhibitor of mammalian target of rapamycin complex 1 (mTORC1). We show that disrupted pathfinding in migrating mouse neural progenitor cells in vitro caused by STRADA depletion is prevented by mTORC1 inhibition with rapamycin or inhibition of its downstream effector p70 S6 kinase (p70S6K) with the drug PF-4708671 (p70S6Ki). We demonstrate that rapamycin can rescue aberrant cortical lamination and heterotopia associated with STRADA depletion in the mouse cerebral cortex. Constitutive mTORC1 signaling and a migration defect observed in fibroblasts from patients with PMSE were also prevented by mTORC1 inhibition. On the basis of these preclinical findings, we treated five PMSE patients with sirolimus (rapamycin) without complication and observed a reduction in seizure frequency and an improvement in receptive language. Our findings demonstrate a mechanistic link between STRADA loss and mTORC1 hyperactivity in PMSE, and suggest that mTORC1 inhibition may be a potential treatment for PMSE as well as other mTOR-associated neurodevelopmental disorders.

Enhanced epidermal growth factor, hepatocyte growth factor, and vascular endothelial growth factor expression in tuberous sclerosis complex.

Epidermal growth factor (EGF), hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF) regulate angiogenesis and cell growth in the developing brain. EGF, HGF, and VEGF modulate the activity of the mammalian target of rapamycin (mTOR) cascade, a pathway regulating cell growth that is aberrantly activated in tuberous sclerosis complex (TSC). We hypothesized that expression of EGF, HGF, VEGF, and their receptors EGFR, c-Met, and Flt-1, respectively, would be altered in TSC. We show by cDNA array and immunohistochemical analysis that EGF, EGFR, HGF, c-Met, and VEGF, but not Flt-1, mRNA, and protein expression was up-regulated in Tsc1 conditional knockout (Tsc1(GFAP)CKO) mouse cortex. Importantly, these alterations closely predicted enhanced expression of these proteins in tuber and subependymal giant cell astrocytoma (SEGA) specimens in TSC. Expression of EGF, EGFR, HGF, c-Met, and VEGF protein, as well as hypoxia inducible factor-1α, a transcription factor that regulates VEGF levels and is also modulated by mTOR cascade activity, was enhanced in SEGAs (n = 6) and tubers (n = 10) from 15 TSC patients. Enhanced expression of these growth factors and growth factor receptors in human SEGAs and tubers and in the Tsc1(GFAP)CKO mouse may account for enhanced cellular growth and proliferation in tubers and SEGAs and provides potential target molecules for therapeutic development in TSC.

Early progenitor cell marker expression distinguishes type II from type I focal cortical dysplasias.

Type I and type II focal cortical dysplasias (FCDs) exhibit distinct histopathologic features that suggest different pathogenic mechanisms. Type I FCDs are characterized by mild laminar disorganization and hypertrophic neurons, whereas type II FCDs exhibit dramatic laminar disorganization and cytomegalic cells (balloon cells). Both FCD types are associated with intractable epilepsy; therefore, identifying cellular or molecular differences between these lesion types that explains the histologic differences could provide new diagnostic and therapeutic insights. Type II FCDs express nestin, a neuroglial progenitor protein that is modulated in vitro by the stem cell proteins c-Myc, sex-determining region Y-box 2 (SOX2), and Octamer-4 (Oct-4) after activation of mammalian target of rapamycin complex 1 (mTORC1). Because mTORC1 activation has been demonstrated in type II FCDs, we hypothesized that c-Myc, SOX2, and Oct-4 expression would distinguish type II from type I FCDs. In addition, we assayed the expression of progenitor cell proteins forkhead box G1 (FOXG1), Kruppel-like factor 4 (KLF4), Nanog, and SOX3. Differential expression of 7 stem cellproteins and aberrant phosphorylation of2mTORC1 substrates, S6 andS6 kinase 1 proteins, clearly distinguished type II from type I FCDs(n = 10 each). Our results demonstrate new potential pathogenic pathways in type II FCDs and suggest biomarkers for diagnostic pathology in resected epilepsy specimens.

Akt pathway is hypoactivated by synergistic actions of diabetes mellitus and hypercholesterolemia resulting in advanced coronary artery disease.

Atherosclerosis is an inflammatory process leading to enhanced cellular proliferation, apoptosis, and vasa vasorum (VV) neovascularization. While both diabetes mellitus (DM) and hypercholesterolemia (HC) predispose to atherosclerosis, the precise interaction of these risk factors is unclear. Akt is a central node in signaling pathways important for inflammation, and we hypothesized that DM/HC would lead to aberrant Akt signaling and advanced, complex atherosclerosis. DM was induced in pigs by streptozotocin and HC by a high-fat diet. Animals were randomized to control (non-DM, non-HC), DM only, HC only, and DM/HC groups. Coronary artery homogenates were analyzed by immunoblotting for proteins involved in the Akt pathway, including phosphorylated (p)-Akt (Ser473), p-GSK-3beta (Ser9), activated NF-kappaB p65, and VEGF. Immunohistochemical staining for Ki67 (cell proliferation), terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) (apoptosis), and von Willebrand factor (vWF) (neovascularization) was performed. Neovascularization was visualized with micro-computerized tomography (CT). Only DM/HC animals developed advanced atherosclerosis and showed decreased p-Akt (Ser473) and p-GSK-3beta (Ser9) levels (P < 0.01 and P < 0.05, respectively). DM/HC arteries demonstrated increased cellular proliferation (P < 0.001), apoptosis (P < 0.01), and activation of NF-kappaB p65 (P < 0.05). Induction of DM/HC also resulted in significant VV neovascularization by enhanced VEGF expression (P < 0.05), increased vWF staining (P < 0.01), and increased density by micro-CT. In conclusion, DM and HC synergistically resulted in complex atherosclerosis associated with attenuated p-Akt (Ser473) levels. Aberrant Akt signaling correlated with increased inflammation, cellular proliferation, apoptosis, and VV neovascularization. Our results revealed a synergistic effect of DM and HC in triggering abnormal Akt signaling, resulting in advanced atherosclerosis.

STRADalpha deficiency results in aberrant mTORC1 signaling during corticogenesis in humans and mice.

Polyhydramnios, megalencephaly, and symptomatic epilepsy syndrome (PMSE) is a rare human autosomal-recessive disorder characterized by abnormal brain development, cognitive disability, and intractable epilepsy. It is caused by homozygous deletions of STE20-related kinase adaptor alpha (STRADA). The underlying pathogenic mechanisms of PMSE and the role of STRADA in cortical development remain unknown. Here, we found that a human PMSE brain exhibits cytomegaly, neuronal heterotopia, and aberrant activation of mammalian target of rapamycin complex 1 (mTORC1) signaling. STRADalpha normally binds and exports the protein kinase LKB1 out of the nucleus, leading to suppression of the mTORC1 pathway. We found that neurons in human PMSE cortex exhibited abnormal nuclear localization of LKB1. To investigate this further, we modeled PMSE in mouse neural progenitor cells (mNPCs) in vitro and in developing mouse cortex in vivo by knocking down STRADalpha expression. STRADalpha-deficient mNPCs were cytomegalic and showed aberrant rapamycin-dependent activation of mTORC1 in association with abnormal nuclear localization of LKB1. Consistent with the observations in human PMSE brain, knockdown of STRADalpha in vivo resulted in cortical malformation, enhanced mTORC1 activation, and abnormal nuclear localization of LKB1. Thus, we suggest that the aberrant nuclear accumulation of LKB1 caused by STRADalpha deficiency contributes to hyperactivation of mTORC1 signaling and disruption of neuronal lamination during corticogenesis, and thereby the neurological features associated with PMSE.

The tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that results from mutations in the TSC1 or TSC2 genes and is associated with hamartoma formation in multiple organ systems. The neurological manifestations of TSC are particularly challenging and include infantile spasms, intractable epilepsy, cognitive disabilities, and autism. Progress over the past 15 years has demonstrated that the TSC1 or TSC2 encoded proteins modulate cell function via the mTOR signaling cascade and serve as keystones in regulating cell growth and proliferation. The mTOR pathway provides an intersection for an intricate network of protein cascades that respond to cellular nutrition, energy levels, and growth-factor stimulation. In the brain, TSC1 and TSC2 have been implicated in cell body size, dendritic arborization, axonal outgrowth and targeting, neuronal migration, cortical lamination, and spine formation. Antagonism of the mTOR pathway with rapamycin and related compounds may provide new therapeutic options for TSC patients.

Embryoid body-mediated differentiation of mouse embryonic stem cells along a hepatocyte lineage: insights from gene expression profiles.

Pluripotent embryonic stem (ES) cells represent a promising renewable cell source for the generation of functional differentiated cells. Previous studies incorporating embryoid body (EB)-mediated stem cell differentiation have, either spontaneously or after growth factor and extracellular matrix protein supplementation, yielded populations of hepatocyte lineage cells expressing mature hepatocyte markers such as albumin (ALB). In an effort to promote ES cell commitment to the hepatocyte lineage, we have evaluated the effects of four culture conditions on albumin and gene expression in differentiating ES cells. Quantitative in situ immunofluorescence and cDNA microarray analyses were used to describe not only lineage specificity but also to provide insights into the effects of disparate culture environments on the mechanisms of differentiation. The results of these studies suggest that spontaneous and collagen-mediated differentiation induce cells with the highest levels of ALB expression but mature liver specific genes were only expressed in the spontaneous condition. Further analysis of gene expression profiles indicated that two distinct mechanisms may govern spontaneous and collagen-mediated differentiation.