Hyperoxia impairs induced pluripotent stem cell-derived endothelial cells and drives an atherosclerosis-like transcriptional phenotype.

Background: Induced pluripotent stem cells (iPSCs) directed to endothelial identity (iPSC-ECs) are emerging as a potent tool for regenerative medicine in vascular disease. However, iPSC-ECs lose expression of key identity markers under standard in vitro conditions, limiting their clinical applications. Methods: To model physiological in vivo conditions, we examined the bioenergetics, presence of key cell markers, and proliferative and angiogenic capacity in iPSC-ECs at late and early passage under hyperoxic (21%) and physiological (4%) oxygen concentrations. Results: Physoxia resulted in relative preservation of mitochondrial bioenergetic activity, as well as CD144 expression in late passage iPSC-ECs, but not proliferative capacity or tube formation. Single cell RNA sequencing (scRNA-seq) revealed that late passage hyperoxic iPSC-ECs develop an endothelial-to-mesenchymal phenotype. Comparing scRNA-seq data from iPSC-ECs and from atherosclerotic ECs revealed overlap of their transcriptional phenotypes. Conclusions: Taken together, our studies demonstrate that physiological 4% oxygen culture conditions were sufficient to improve mitochondrial function in high passage cells, but alone was insufficient to preserve angiogenic capacity. Furthermore, late passage cells under typical conditions take on an endothelial-to-mesenchymal phenotype with similarities to ECs found in atherosclerosis.

Unconscious bias in speaker introductions at a national vascular surgery meeting: The impact of rank, race and gender.

OBJECTIVES: Unconscious bias can impact manner of speaker introductions in formal academic settings. We examined speaker introductions at the Society of Vascular Surgeons Annual Meeting to determine factors associated with non-professional address. METHODS: We examined speaker introductions from the 2019 SVS Vascular Annual Meeting. Professional title with either full name or last name was considered professional address. Speaker and moderator demographics were collected. Univariate and multivariate logistic regression analyses were performed to identify associations between introduction and speaker and moderator characteristics. RESULTS: 336 talks met inclusion criteria. Both speakers and moderators were more likely to be white (63.4 â€‹% and 65.8 â€‹%,p â€‹= â€‹0.92), man (75.6 â€‹% and 74.4 â€‹%,p â€‹= â€‹0.82) and full professor rank (34.5 â€‹% and 42.3 â€‹%, p â€‹< â€‹0.001). On multivariable regression, non-professional address was associated with speaker rank of trainee (OR 3.13, p â€‹= â€‹0.05) and when moderator was white (OR 2.42, p â€‹= â€‹0.03). CONCLUSIONS: This study emphasizes the potential negative impact of unconscious bias at a national meeting for vascular surgeons and the need to mitigate this effect at the organization level.

Single-Cell RNA sequencing investigation of female-male differences under PAD conditions.

Peripheral arterial disease (PAD) is an age-related medical condition affecting mostly muscular arteries of the limb. It is the 3rd leading cause of atherosclerotic morbidity. The mechanical environment of endothelial cells (ECs) in PAD is characterized by disturbed blood flow (d-flow) and stiff extracellular matrices. In PAD, the stiffness of arteries is due to decreased elastin function and increased collagen content. These flow and stiffness parameters are largely missing from current models of PAD. It has been previously proven that ECs exposed to d-flow or stiff substrates lead to proatherogenic pathways, but the effect of both, d-flow and stiffness, on EC phenotype has not been fully investigated. In this study, we sought to explore the effect of sex on proatherogenic pathways that could result from exposing endothelial cells to a d-flow and stiff environment. We utilized the scRNA-seq tool to analyze the gene expression of ECs exposed to the different mechanical conditions both in vitro and in vivo. We found that male ECs exposed to different mechanical stimuli presented higher expression of genes related to fibrosis and d-flow in vitro. We validated our findings in vivo by exposing murine carotid arteries to d-flow via partial carotid artery ligation. Since women have delayed onset of arterial stiffening and subsequent PAD, this work may provide a framework for some of the pathways in which biological sex interacts with sex-based differences in PAD.

Efficacy and safety of sonographer discretion to terminate a venous duplex ultrasound for diagnosis of deep vein thrombosis in coronavirus disease 2019 patients.

OBJECTIVE: Sonographers performing venous duplex ultrasound (VDUS) of patients with coronavirus disease 2019 (COVID-19) have an increased risk of exposure owing to their close contact with these patients for an extended period. The objective of the present study was to evaluate the efficacy of a modified COVID-19 VDUS protocol to reduce sonographer exposure to COVID-19 patients. METHODS: We performed a single-center retrospective review. Patients who had undergone VDUS under the modified COVID-19 protocol between March 1, 2020, and June 30, 2020, with a confirmed or presumed COVID-19 diagnosis at the VDUS were included. The modified COVID-19 protocol was defined as the ability of the sonographer to terminate the examination on detection of an acute deep vein thrombosis (DVT). The primary outcome measures were the number of anatomic deep venous segments recorded by the sonographer, which was used as a surrogate measure for sonographer exposure time, and the number of acute DVTs found on follow-up examinations in segments not visualized at the index VDUS. RESULTS: A total of 160 lower extremity VDUS (LEVDUS) scans and 72 upper extremity VDUS (UEVDUS) scans were performed using the modified COVID-19 protocol. The index VDUS had found an acute DVT for 44 of 160 patients (27.5%) who had undergone LEVDUS and 26 of 72 (36.6%) who had undergone UEVDUS. On follow-up imaging, 7 of 38 LEVDUS scans (17.9%) and 1 of 10 UEVDUS scans (10%) had demonstrated a new acute DVT. Malignancy and surgery 30 days before imaging were significantly associated with acute lower extremity DVT, and mechanical ventilation and extracorporeal membrane oxygenation were associated with acute upper extremity DVT. On the index VDUS, the average was 10.6 of 12 total visualized segments on LEVDUS and 6.4 of 10 total segments on UEVDUS. Of the index VDUS scans, 35.6% of the LEVDUS and 78.6% of the UEVDUS scans had been abbreviated. The index VDUS scans that were positive for acute DVT had had significantly fewer visualized segments for both lower (8.4 vs 11.5; P < .0001) and upper (4.2 vs 7.6) extremities (P < .0001). On the follow-up examinations, only one of eight new acute DVTs had been found in a patient whose index VDUS had been abbreviated and the corresponding segment not assessed. These findings did not affect the patient's clinical course. CONCLUSIONS: The modified COVID-19 VDUS protocol reduced sonographers' potential exposure time to COVID-19. Additionally, the clinical efficacy was maintained, with no missed DVTs, despite the abbreviation of the VDUS examinations.

Autophagy Enhances Longevity of Induced Pluripotent Stem Cell-Derived Endothelium via mTOR-Independent ULK1 Kinase.

Stem cells are enabling an improved understanding of the peripheral arterial disease, and patient-specific stem cell-derived endothelial cells (ECs) present major advantages as a therapeutic modality. However, applications of patient-specific induced pluripotent stem cell (iPSC)-derived ECs are limited by rapid loss of mature cellular function in culture. We hypothesized that changes in autophagy impact the phenotype and cellular proliferation of iPSC-ECs. Endothelial cells were differentiated from distinct induced pluripotent stem cell lines in 2D culture and purified for CD144 positive cells. Autophagy, mitochondrial morphology, and proliferation were characterized during differentiation and over serial passages in culture. We found that autophagy activity was stimulated during differentiation but stagnated in mature iPSC-ECs. Mitochondria remodeled through mitophagy during differentiation and demonstrated increasing membrane potential and mass through serial passages; however, these plateaued, coinciding with decreased proliferation. To evaluate for oxidative damage, iPSC-ECs were alternatively grown under hypoxic culture conditions; however, hypoxia only transiently improved the proliferation. Stimulating mTOR-independent ULK1-mediated autophagy with a plant derivative AMP kinase activator Rg2 significantly improved proliferative capacity of iPSC-ECs over multiple passages. Therefore, autophagy, a known mediator of longevity, played an active role in remodeling mitochondria during maturation from pluripotency to a terminally differentiated state. Autophagy failed to compensate for increasing mitochondrial mass over serial passages, which correlated with loss of proliferation in iPSC-ECs. Stimulating ULK1-kinase-driven autophagy conferred improved proliferation and longevity over multiple passages in culture. This represents a novel approach to overcoming a major barrier limiting the use of iPSC-ECs for clinical and research applications.

Direct oral anticoagulants decrease treatment failure for acute lower extremity deep venous thrombosis.

OBJECTIVE: Optimal medical therapy for acute lower extremity deep venous thrombosis (DVT) remains an enigma. While clinical trials demonstrate non-inferiority with an oral anti-Xa inhibitor, or direct oral anticoagulant (DOAC), versus combined low-molecular weight heparin (LMWH) and oral vitamin K antagonist (VKA), the most effective regimen remains to be determined. METHODS: This study is a single-center retrospective cohort study from October 2014 to December 2015 of patients with a diagnosis of acute DVT and subsequent serial lower extremity venous duplex. Demographics, medical history, medications, serial ultrasound findings, as well as the primary anticoagulant used for treatment were collected and analyzed by two independent data extractors. Treatment failure was defined as any new DVT or progression of an existing DVT within 3 months of diagnosis of the index clot. Risk factors for treatment failure were assessed using standard odds ratios and Fischer's exact test. RESULTS: Among 496 patients with an acute lower extremity DVT, 54% (n = 266) were men, mean age was 61 years, 35% (n = 174) involved the popliteal or more proximal segments, and 442 had documentation of the primary treatment for DVT: 20% (n = 90) received nothing; 20% (n = 92) received an oral VKA; 34% (n = 149) received a DOAC; 20% (n = 90) received LMWH; and 5% (n = 21) received another class of anticoagulant. Within 3 months, 21% (n=89 out of 427) had treatment failure defined as any new DVT or progression of prior DVT. Patients treated with a DOAC were less likely to experience treatment failure when compared with any other treatment (odds ratio 0.43; 95% confidence intervals [0.23, 0.79]; p = 0.0069) and when compared with traditional oral VKA (OR 0.44; 95% CI [0.21, 0.92]; p = 0.029). None of prior history of DVT, pulmonary embolism, thrombophilia, renal insufficiency, hepatic insufficiency, cancer, or antiplatelet therapy correlated with treatment failure. Treatment outcome did not correlate with being on any anticoagulation versus none (p = 0.74), nor did it correlate with the duration of treatment (<3 months versus ≥3 months) (p = 0.42). Proximal and distal DVTs showed no difference in treatment failure (19% versus 22%, respectively; p = 0.43). CONCLUSION: In summary, the use of a DOAC for acute lower extremity DVT yielded better overall outcomes and fewer treatment failures at 3 months as compared to traditional oral VKA therapy based on serial duplex imaging.

Modifiable risk factors for burnout in vascular surgery trainees.

OBJECTIVE: Burnout is prevalent among vascular surgery trainees. Here we aim to identify modifiable risk factors for burnout in vascular surgery training, to facilitate the development of programs to enhance and sustain trainee well-being. METHODS: The Association of Program Directors in Vascular Surgery issued the Annual Training survey in the fall of 2018 to all trainees. The survey contained items to assess frequency of burnout, as well as mentorship, training environment, and stress coping mechanisms using an abbreviated COPE (Coping Orientation to Problems Experienced) inventory. RESULTS: Of 628 surveys issued, the response rate was 30% (n = 188). Respondents indicated that the majority of programs offer mentorship opportunities (n = 150 [83%]) that are longitudinal throughout the duration of training (n = 140 [77%]). Fifty-eight percent (n = 109) indicated there was an appropriate balance between learning and productivity in their program, with more respondents leaning toward too much clinical productivity (n = 57) and fewer toward too much learning (n = 19). Forty-five percent of respondents indicated feeling burnout at least weekly (n = 81). The burnout group was less likely to report an appropriate balance between clinical productivity and learning (49.4% vs 67.7%; P < .001), as well as a lower frequency of mentorship opportunities (72.1% vs 92.7%; P < .001). Certain coping skills were used more frequently in the burnout group, including self-distraction, disengagement, humor, self-blame, and substance use. In multivariate analysis, frequent use of self-blame conferred a 9.847-fold increased risk (95% confidence interval, 2.114-45.871) of burnout (P = .003), while feeling appropriately challenged by the faculty was significantly protective (odds ratio for burnout, 0.158; 95% confidence interval, 0.031-0.820; P = .03). CONCLUSIONS: The protective effect against vascular surgery trainee burnout conferred by the availability of mentorship suggests that an expansion and emphasis on mentorship in training may help to mitigate trainee burnout. Mentorship may also be a suitable channel to assess for an appropriate level of challenge, as well as for an appropriate balance between clinical productivity and learning that, when present, are also protective against burnout. Furthermore, the correlation between the frequent use of certain coping skills and burnout highlight this as an area for intervention, potentially through a combination of mentor modeling and formal training on healthy stress-related coping strategies.

Evidence-Based Bundled Quality Improvement Intervention for Reducing Surgical Site Infection in Lower Extremity Vascular Bypass Procedures.

BACKGROUND: Surgical site infection (SSI) poses a significant burden to patients and healthcare resources. Vascular Quality Initiative (VQI) data identify a higher rate of SSIs for lower extremity bypass than other vascular procedures. Bundled interventions have successfully reduced SSIs in other surgical procedures. STUDY DESIGN: We evaluated our institution-specific VQI data for modifiable risk factors associated with index hospitalization SSI from January 2012 through October 2015. We implemented an evidence-based lower extremity bypass operation SSI reduction bundle (ie perioperative chlorhexidine showers and transverse groin incisions) and prospectively enrolled all patients who had lower extremity bypass procedures, with a target adherence rate of 50% per bundle component. Bundle adherence and SSI events were measured from March 2016 through August 2017. We carried out a pre-post evaluation of bundle effectiveness in reducing index hospitalization SSI. RESULTS: In the pre-intervention period, 43 of 234 (18%) patients had SSI events. The only risk factors associated with SSI (ie female sex, diabetes, overweight BMI) were not readily modifiable. In an 18-month period after introduction of our intervention, adherence rates to preoperative chlorhexidine showers, a transverse incision, and a postoperative chlorhexidine shower were 71% (52 of 73), 48% (24 of 50), and 88% (64 of 73), respectively. Compliance with all applicable bundle components was 36% (26 of 73). The SSI rate post-intervention decreased from 18% to 4% (3 of 73). Intention-to-treat multivariable analysis showed a 97% SSI risk reduction with the bundle (p = 0.002). As-treated analysis identified 85% (p = 0.02) and 62% (p = 0.047) SSI risk reductions from the preoperative and postoperative chlorhexidine showers, respectively. CONCLUSIONS: In this evaluation study of the effectiveness of a quality improvement intervention, SSIs were markedly decreased after implementation of our evidence-based bundle for lower extremity vascular bypass procedures.

Impact of Body Mass Index on Outcomes after Mesenteric Revascularization for Chronic Mesenteric Ischemia.

BACKGROUND: Historically, patients with chronic mesenteric ischemia (CMI) are underweight with a low body mass index (BMI). However, with the recent obesity epidemic many of these patients now are overweight with a high BMI. We evaluated the impact of BMI on outcomes after mesenteric revascularization for CMI. METHODS: A retrospective chart review of patients undergoing open or endovascular mesenteric revascularization for CMI between January 2000 and June 2015 was performed. Demographics, comorbidities, BMI, Society for Vascular Surgery-combined comorbidity score, treatment modality, postoperative complications, reintervention, and all-cause mortality were analyzed. The primary end point for the study was all-cause mortality at 5 years. Patients were stratified using the World Health Organization BMI criteria. Univariate, Kaplan-Meier survival, and multivariate analyses were performed. RESULTS: In the study period, 104 unique patients underwent mesenteric revascularization for CMI, for 77 of whom BMI information was available. Of these 77, 30 patients were treated by endovascular revascularization, and 47 patients were treated by open revascularization. Overall, 27 (35.1%) were overweight or obese with a BMI ≥25. Median follow-up time was 41 months. High BMI patients were less likely to have weight loss at the time of surgery (P = 0.004). Stratified by BMI <25 versus BMI ≥25, 5-year survival for patients treated by open revascularization was 90% versus 50% (P = 0.02); survival for patients treated by endovascular revascularization was 27% vs. 53% (P = 0.37). Multivariate survival analysis identified active smoking, hypertensive chronic kidney disease, open repair with the use of venous conduit instead of prosthetic conduit (P < 0.001), and history of peripheral arterial disease (PAD) (P = 0.002), as independent predictors of increased all-cause mortality. CONCLUSIONS: BMI needs to be considered in assessing and counseling patients on outcomes of mesenteric revascularization for CMI, as a BMI over 25 is associated with poorer long-term survival after open revascularization. Smoking, hypertensive chronic kidney disease, PAD, and open repair with the use of venous conduit are independent predictors of long-term mortality after mesenteric revascularization independent of BMI.

The autosomal dominant spinocerebellar ataxias: emerging mechanistic themes suggest pervasive Purkinje cell vulnerability.

The spinocerebellar ataxias are a genetically heterogeneous group of disorders with clinically overlapping phenotypes arising from Purkinje cell degeneration, cerebellar atrophy and varying degrees of degeneration of other grey matter regions. For 22 of the 32 subtypes, a genetic cause has been identified. While recurring themes are emerging, there is no clear correlation between the clinical phenotype or penetrance, the type of genetic defect or the category of the disease mechanism, or the neuronal types involved beyond Purkinje cells. These phenomena suggest that cerebellar Purkinje cells may be a uniquely vulnerable neuronal cell type, more susceptible to a wider variety of genetic/cellular insults than most other neuron types.

A conserved eEF2 coding variant in SCA26 leads to loss of translational fidelity and increased susceptibility to proteostatic insult.

The autosomal dominant spinocerebellar ataxias (SCAs) are a genetically heterogeneous group of disorders exhibiting cerebellar atrophy and Purkinje cell degeneration whose subtypes arise from 31 distinct genetic loci. Our group previously published the locus for SCA26 on chromosome 19p13.3. In this study, we performed targeted deep sequencing of the critical interval in order to identify candidate causative variants in individuals from the SCA26 family. We identified a single variant that co-segregates with the disease phenotype that produces a single amino acid substitution in eukaryotic elongation factor 2. This substitution, P596H, sits in a domain critical for maintaining reading frame during translation. The yeast equivalent, P580H EF2, demonstrated impaired translocation, detected as an increased rate of -1 programmed ribosomal frameshift read-through in a dual-luciferase assay for observing translational recoding. This substitution also results in a greater susceptibility to proteostatic disruption, as evidenced by a more robust activation of a reporter gene driven by unfolded protein response activation upon challenge with dithiothreitol or heat shock in our yeast model system. Our results present a compelling candidate mutation and mechanism for the pathogenesis of SCA26 and further support the role of proteostatic disruption in neurodegenerative diseases.

Positive and negative predictors for good outcome after decompressive surgery for Chiari malformation type 1 as scored on the Chicago Chiari Outcome Scale.

OBJECTIVE: Posterior fossa decompression (PFD) is commonly applied as treatment for Chiari malformation type 1 (CM1), an entity which is associated with a variety of presenting symptoms but little data correlating symptoms to surgical outcome. We applied the Chicago Chiari Outcome Scale (CCOS), a novel 16-point tool for evaluating outcome, to a consecutive series of CM1 patients to identify specific factors or symptoms that predispose to a better or worse surgical outcome. METHODS: A series of 167 CM1 patients who underwent initial PFD at our institution (consisting of suboccipital craniectomy, C1 laminectomy, subarachnoid exploration, and expansile autologous pericranial duraplasty) were reviewed. Pre-operative signs, symptoms, and characteristics were recorded, and odds ratios were calculated to identify significant pre-operative factors corresponding to a better or worse outcome on the CCOS. RESULTS: Sensory deficits and peripheral neuropathy correlated with a lower score on the CCOS. Younger age at the time of surgery and, strikingly, presence of syringomyelia both correlated with a higher CCOS score. DISCUSSION: Our results identify specific presenting factors that correlated with a better or worse outcome after CM1 decompression. These data also demonstrate that CCOS scoring allows for a rigorous comparison of outcome in different patient populations and between variable operative techniques. Application of CCOS scoring to a larger patient population undergoing a variety of operative CM1 treatments should allow for better-informed decisions regarding patient selection and treatment options for CM1.

A novel scoring system for assessing Chiari malformation type I treatment outcomes.

BACKGROUND: Outcome assessment for the management of Chiari malformation type 1 is difficult because of the lack of a reliable and specific surgical outcome assessment scale. Such a scale could reliably correlate postoperative outcomes with preoperative symptoms. OBJECTIVE: We developed a novel scoring system and applied it retrospectively to 146 patients treated at our institution in order to create and verify a simple and quantifiable assessment of Chiari outcomes. METHODS: The Chicago Chiari Outcome Scale (CCOS) uses 4 postoperative outcome categories (pain, nonpain symptoms, functionality, and complications) graded 1 to 4 for a total possible score of 16. As a comparison with current Chiari outcome methodology, each patient was also placed into a gestalt outcome group of "improved," "unchanged," or "worse" (I/U/W). Patients were stratified by CCOS scores and by I/U/W group. RESULTS: Stratifying patients by total CCOS scores showed that patients who achieved CCOS scores between 13 and 16 were predominantly in the I/U/W improved group (n = 101, 69%); scores between 9 and 12 were predominantly I/U/W unchanged (n = 39, 27%), and scores between 4 and 8 were I/U/W worse (n = 6, 4%). Symptom subscore results provided insight into the specifics of the overall outcome in addition to the more quantitative nature of the 16-point scale. CONCLUSION: We describe a CCOS that assigns higher scores to patients judged improved by gestalt I/U/W ratings and lower scores to those who were unchanged or worse while defining outcome in 4 specific subcategories. As such, this CCOS should allow for a more unified and quantifiable outcome assessment after Chiari surgery.