Risk Factors for Unplanned Higher-Level Re-Amputation and Mortality after Lower Extremity Amputation in Chronic Limb-Threatening Ischemia.

Background: The factors associated with unplanned higher-level re-amputation (UHRA) and one-year mortality among patients with chronic limb-threatening ischemia (CLTI) after lower extremity amputation are poorly understood. Methods: This was a single-center retrospective study of patients who underwent amputations for CLTI between 2014 and 2017. Unadjusted bivariate analyses and adjusted odds ratios (AOR) from logistic regression models were used to assess associations between pre-amputation risk factors and outcomes (UHRA and one-year mortality). Results: We obtained data on 203 amputations from 182 patients (median age 65 years [interquartile range (IQR) 57, 75]; 70.7% males), including 118 (58.1%) toe, 20 (9.9%) transmetatarsal (TMA), 37 (18.2%) below-knee (BKA), and 28 (13.8%) amputations at or above the knee. Median follow-up was 285 days (IQR 62, 1348). Thirty-six limbs (17.7%) had a UHRA, and the majority of these (72.2%) were following index forefoot amputations. Risk factors for UHRA included non-ambulatory status (AOR 6.74, 95% confidence interval (CI) 1.74-26.18; p < 0.10) and toe pressure < 30 mm Hg (AOR 4.89, 95% CI 1.52-15.78; p < 0.01). One-year mortality was 17.2% (n = 32), and risk factors included coronary artery disease (AOR 3.93, 95% CI 1.56-9.87; p < 0.05), congestive heart failure (AOR 4.90, 95% CI 1.96-12.29; p = 0.001), end-stage renal disease (AOR 7.54, 95% CI 3.10-18.34; p < 0.001), and non-independent ambulation (AOR 4.31, 95% CI 1.20-15.49; p = 0.03). Male sex was associated with a reduced odds of death at 1 year (AOR 0.37, 95% CI 0.15-0.89; p < 0.05). UHRA was not associated with one-year mortality. Conclusions: Rates of UHRA after toe amputations and TMA are high despite revascularization and one-year mortality is high among patients with CLTI requiring amputation.

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.

Open aortic septectomy for complicated type B aortic dissection.

Malperfusion is a complication of acute aortic dissection associated with substantially increased morbidity and mortality. Although endovascular treatment of the dissection with a stent graft to cover the intimal tear and reexpand the true lumen will often be sufficient to treat distal malperfusion, persistent or delayed malperfusion will necessitate additional interventions. Endovascular strategies to increase true lumen expansion include bare metal dissection stent placement and percutaneous fenestration. However, for patients with anatomy not amenable to an endovascular approach, alternative techniques are required. We describe two cases of complicated acute aortic dissection due to partial false lumen thrombosis treated with open aortic septectomy. Although an uncommon procedure, open septectomy can be useful for patients with malperfusion syndromes without appropriate endovascular options.

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.

Application of dissemination and implementation science frameworks to surgical research.

A statistic often quoted is that <15% of research is translated into practice and routine adoption of novel research findings can take up to 17 years. Dissemination and implementation science is a field of research focused on studying and developing approaches that can increase the uptake of such innovations, thereby reducing the significant time lag between scientific discovery and widespread adoption. As such, it can have a major clinical impact by increasing the utilization of proven innovations in routine clinical practice using systematic frameworks to implement, disseminate, and evaluate the successful application of evidence-based practices. Herein, we discuss the background and theory of implementation science, major frameworks and considerations for study design, and current examples of its application in surgical research.

Characterizing endovascular aortic intervention outcomes for nonruptured aortic aneurysms by physician specialty.

BACKGROUND: Evaluate patient outcomes after endovascular aortic interventions performed for nonruptured aortic aneurysms by physician specialties. METHODS: Endovascular aortic repair (EVAR), fenestrated or branched repair (F-BEVAR), and thoracic endovascular aortic repair (TEVAR) procedures were obtained from the Illinois Hospital Association Comparative Health Care and Hospital Data Reporting Services database from 2016 to 2019. Logistic and Poisson regression were used to determine outcomes by patient, physician, and hospital characteristics. RESULTS: A total of 4,935 procedures, 3,666 (74.3%) EVAR, 567 (11.5%) F-BEVAR, and 702 (14.2%) TEVAR were performed by vascular surgeons, interventional radiologists, interventional cardiologists, and cardiac surgeons. Vascular surgeons performed interventions equally between hospital types while interventional radiologists primarily performed interventions in teaching hospitals (68.1%) and interventional cardiologists and cardiac surgeons typically performed interventions in community hospitals (91.8% and 82.1%, respectively; P < .001). No differences in inpatient mortality were noted between specialties. Patients treated by interventional radiologists had increased odds of staying in the hospital ≥8 days (odd ration [OR] 1.95, 95% confidence interval [CI] 1.19-3.19) and patients treated by interventional cardiologists had lower odds of being admitted to the intensive care unit [ICU] (OR 0.42, 95% CI 0.18-0.95). CONCLUSION: Differences in practice patterns among specialties performing endovascular aortic aneurysm repair for nonruptured aneurysms suggest opportunities for collaboration to optimize quality of care.

Identifying gaps in disease knowledge among patients with peripheral artery disease.

OBJECTIVE: An individual's understanding of disease risk factors and outcomes is important for the ability to make healthy lifestyle choices and decisions about disease treatment. Peripheral artery disease (PAD) is a condition with increasing global prevalence and high risk of adverse patient outcomes. This study seeks to understand the adequacy of disease understanding in patients with PAD. METHODS: This was an observational study of patients with PAD recruited from vascular surgery outpatient clinic and PAD clinical studies at a single academic medical center over an 8-month period. A 44-item paper survey assessed demographic and socioeconomic information, knowledge of personal medical history, PAD risk factors, consequences of PAD, and health education preferences. Patients with documented presence of PAD were offered the survey. Patients unable to complete the survey or provide informed consent were not considered eligible. Disease "awareness" was defined as correct acknowledgement of the presence or absence of a disease, including PAD, in the personal medical history. "PAD knowledge score" was the percentage of correct responses to questions on general PAD risk factors and consequences. Of 126 eligible patients, 109 participated. Bivariate analysis was used to study factors associated with awareness of PAD diagnosis. Factors associated with the PAD knowledge score were studied using the Pearson correlation coefficient, two-sample t test, or one-way analysis of variance. P value < .05 was considered statistically significant. RESULTS: The mean participant age was 69.4 ± 11.0 years, and 39.4% (n = 43) were female. Most participants (78.9%; n = 86) had critical limb-threatening ischemia. Only 65.4% (n = 70) of participants were aware of a diagnosis of PAD, which was less than their awareness of related comorbidities. Factors positively associated with PAD diagnosis awareness were female sex (81.4% vs 54.7%; P = .004) and history of percutaneous leg revascularization (78.6% vs 47.9%; P = .001). Among 17 patients who had undergone major leg amputation, 35% (n = 6) were unaware of a diagnosis of PAD. PAD knowledge scores correlated positively with an awareness of PAD diagnosis (59.1% vs 48.7%; P = .02) and negatively with a history of hypertension (53.4% vs 68.1%; P = .001). Most participants (86.5%; n = 90) expressed a desire to be further educated on PAD. The most popular education topics were dietary recommendations, causes, and treatment for PAD. CONCLUSIONS: Patients with PAD have deficits in their awareness of this diagnosis and general knowledge about PAD. Future research priorities should further define these deficits and their causes in order to inform new strategies that foster information-seeking behavior and effective educational programs for PAD.

Current status of patient-reported outcome measures in vascular surgery.

A previously published review focused on generic and disease-specific patient-reported outcome measures (PROMs) relevant to vascular surgery but limited to arterial conditions. The objective of this project was to identify all available PROMs relevant to diseases treated by vascular surgeons and to evaluate vascular surgeon perceptions, barriers to widespread implementation, and concerns regarding PROMs. We provide an overview of what a PROM is and how they are developed, and summarize currently available PROMs specific to vascular surgeons. We also report results from a survey of 78 Society for Vascular Surgery members serving on committees within the Policy and Advocacy Council addressing the barriers and facilitators to using PROMs in clinical practice. Finally, we report the qualitative results of two focus groups conducted to assess granular perceptions of PROMS and preparedness of vascular surgeons for widespread implementation of PROMs. These focus groups identified a lack of awareness of existing PROMs, knowledge of how PROMs are developed and validated, and clarity around how PROMs should be used by the clinician as main subthemes for barriers to PROM implementation in clinical practice.

Why Temporary Filters Are Not Removed: Clinical Predictors in 1,000 Consecutive Cases.

BACKGROUND: Compared to permanent inferior vena cava (IVC) filters, higher complication rates occur with long-term use of temporary IVC filters. We aimed to identify patient clinical factors at the time of placement that could predict failure to remove a temporary IVC filter. METHODS: A retrospective review was performed of both vascular surgery and interventional radiology prospective databases between December 2008 and December 2013. We analyzed a total number of 1,024 consecutive, temporary IVC filters stratified by whether retrieval was attempted or made permanent. Univariate, multivariate, and prediction modeling analyses with internal validation were performed on abstracted data, which included risk factors, treatment modalities, and indications for IVC filter placement. RESULTS: Of 1,024 temporary IVC filters, removal was attempted in 60% and no attempt at removal (kept permanent) in 40%. Of the 619 with attempted removal, the overall successful retrieval rate was 95%. The majority of filters were not attempted to be removed because of persistent filter indications (360 cases). Risk factors associated with IVC filter permanence included male sex, older age, history, or indication of venous thromboembolism (VTE) with inability to anticoagulate, malignancy, and neurologic condition. Risk factors most predictive of permanence in the multivariate model were malignancy (odds ratio [OR]: 3.0, P < 0.001) or neurologic disorder (OR: 2.69, P = 0.0005). Validation revealed our model had a sensitivity of 60.4% and specificity of 69.9%. CONCLUSIONS: Our study shows that patients who are more likely to have a temporary IVC filter kept permanent are more likely to be older males with a history of malignancy, neurologic condition, or VTE. These factors are also predictive of permanence and can be used in our predictive model to provide insight into the significant preoperative risk factors that should play into the decision-making process.

Surveillance, anticoagulation, or filter in calf vein thrombosis.

OBJECTIVE: This study compared the efficacy and complication rates of inferior vena cava (IVC) filters for calf vein thrombosis (CVT) vs conservative treatment with or without anticoagulation. METHODS: Vascular laboratory studies of patients who had an isolated CVT (anterior and posterior tibialis, peroneal, soleal, and gastrocnemius veins) from April 2009 to January 2014 were retrospectively analyzed from a single institution. Of 647 patients with isolated CVT, 285 (44%) received an IVC filter, and 362 (56%) received medical treatment alone (38.9% surveillance, 11.6% prophylactic anticoagulation, and 49.4% therapeutic anticoagulation). Univariate, multivariate, propensity matching, and Kaplan-Meier analyses were performed on abstracted data, which included, but was not limited to, risk factors, treatment modalities, venous thromboembolism (VTE) complications (defined as propagation of deep vein thrombosis [DVT] or pulmonary embolism [PE]), bleeding complications, and IVC filter-related complications (ie, filter tilting >15°, perforation >3 mm, fracture, migration >10 mm). RESULTS: The overall incidence of PE in was 2.5% in the IVC filter group and 3.3% in the medical group (P = .27). The overall incidence of VTE complications (propagation of DVT, PE) was 35% for the surveillance group without anticoagulation, 30% in patients treated with prophylactic anticoagulation, and 10% in patients treated with therapeutic anticoagulation (P = .0003). Only a minority of patients underwent duplex ultrasound imaging after filter insertion. In the IVC filter group, the most common reasons that contraindicated anticoagulation were bleeding (35%) or recent surgery (27%). The number of IVC filter-related complications in the IVC filter group was 29 (10%). Because the IVC filter group was older (mean age, 65 vs 61 years, P = .004) and more likely to have a history of thromboembolic events (56% vs 16%, P < .0001), and malignancy (49% vs 28%, P < .0001), propensity analyses were performed yielding a homogenous cohort. The overall complication and thromboembolic rates did not differ for muscular (soleal, gastrocnemius) vs tibial DVTs (anterior, posterior, peroneal veins). CONCLUSIONS: The use of anticoagulation in patients with CVT significantly decreases the rates of VTE complications. The use of IVC filters in this study was associated with a 10% complication rate and did not significantly reduce the incidence of PE. Nevertheless, given the overall low rates of PE and the higher risk of VTE in patients who receive filters, the decision to insert a filter in patients with calf CVT should be individualized.

Long-term effect of PROLI/NO on cellular proliferation and phenotype after arterial injury.

Vascular interventions are associated with high failure rates from restenosis secondary to negative remodeling and neointimal hyperplasia. Periadventitial delivery of nitric oxide (NO) inhibits neointimal hyperplasia, preserving lumen patency. With the development of new localized delivery vehicles, NO-based therapies remain a promising therapeutic avenue for the prevention of restenosis. While the time course of events during neointimal development has been well established, a full characterization of the impact of NO donors on the cells that comprise the arterial wall has not been performed. Thus, the aim of our study was to perform a detailed assessment of proliferation, cellularity, inflammation, and phenotypic cellular modulation in injured arteries treated with the short-lived NO donor, PROLI/NO. PROLI/NO provided durable inhibition of neointimal hyperplasia for 6 months after arterial injury. PROLI/NO inhibited proliferation and cellularity in the media and intima at all of the time points studied. However, PROLI/NO caused an increase in adventitial proliferation at 2 weeks, resulting in increased cellularity at 2 and 8 weeks compared to injury alone. PROLI/NO promoted local protein S-nitrosation and increased local tyrosine nitration, without measurable systemic effects. PROLI/NO predominantly inhibited contractile smooth muscle cells in the intima and media, and had little to no effect on vascular smooth muscle cells or myofibroblasts in the adventitia. Finally, PROLI/NO caused a delayed and decreased leukocyte infiltration response after injury. Our results show that a short-lived NO donor exerts durable effects on proliferation, phenotype modulation, and inflammation that result in long-term inhibition of neointimal hyperplasia.

Treatment options for symptomatic carotid stenosis: timing and approach.

Stroke is a major cause of morbidity and mortality and up to 15-20% of ischemic strokes can be attributed to atherosclerotic internal carotid artery disease. The treatment of carotid artery disease has been the subject of a wealth of literature in the past twenty years since the publication of the landmark randomized controlled trials, the North American Symptomatic Carotid Endarterectomy Trial and the European Carotid Surgery Trial, in the early 1990s. Although these landmark trials have helped establish the current guidelines for treatment of patients with symptomatic carotid artery disease, there have since been major advancements in the medical treatment of cardiovascular disease and there still remains a great deal of controversy regarding the timing and technical approach to carotid revascularization. In particular, there has been a wealth of literature to determine whether carotid endarterectomy or carotid stenting should be used for revascularization and when this revascularization should occur following onset of symptoms. This update offers an overview of the standards for diagnosis and medical treatment of patients with symptomatic carotid artery disease, the indications for surgical revascularization and a review of the most pertinent literature as it pertains to the more controversial issues of technical approach and timing of surgical revascularization following onset of symptoms in patients with carotid artery disease.

Debate: Whether evidence supports reducing the threshold diameter to 5 cm for elective interventions in women with abdominal aortic aneurysms.

Current practice guidelines recommend repair of asymptomatic abdominal aortic aneurysms once they reach the 5.5-cm-diameter threshold and are based on information from randomized controlled trials. However, because aneurysms are more common in men, women are under-represented in these trials, and questions persist about whether this repair threshold should apply to them. In addition, women have smaller aortas to begin with and in most aneurysm cohorts are older, have more atherosclerotic risk factors, are less likely to be anatomic candidates for endovascular repair, and do poorer after emergency or elective repair of their aneurysm. These are just some of the issues that our discussants address in determining whether the repair threshold should be at a smaller diameter for women.

The utility of venous thromboembolism risk assessment models in general and vascular surgery.

Venous thromboembolism (VTE) is a common postsurgical complication, the incidence of which can be reduced with the use of various prophylactic measures. Proper use of these measures requires an understanding of each individual patient's risk of VTE. Risk assessment models have been developed to aid clinicians in quantifying the likelihood of an individual VTE formation. In this review, we discuss several models of risk assessment for general and vascular surgery patients with a focus on both sensitivity and prospective validation by external sources. In addition, strategies to improve proper implementation of prophylactic measures are highlighted.

Nitric oxide is less effective at inhibiting neointimal hyperplasia in spontaneously hypertensive rats.

Exogenous administration of nitric oxide (NO) markedly decreases neointimal hyperplasia following arterial injury in several animal models. However, the effect of NO on neointimal hyperplasia in hypertension remains unknown. Here, we employ the spontaneously hypertensive rat (SHR) strain, inbred from Wistar Kyoto (WKY) rats, and the carotid artery balloon injury model to assess the effects of NO on neointimal hyperplasia development. 2weeks after arterial injury, we showed that both rat strains developed similar levels of neointimal hyperplasia, but local administration of NO was less effective at inhibiting neointimal hyperplasia in the SHR compared to WKY rats (58% vs. 79%, P<0.001). Interestingly, local administration of NO did not affect systemic blood pressure in either rat strain. Compared to WKY, the SHR displayed more proliferation in the media and adventitia following balloon injury, as measured by BrdU incorporation. The SHR also showed more inflammation in the adventitia after injury, as well as more vasa vasorum, than WKY rats. NO treatment reduced the vasa vasorum in the SHR but not WKY rats. Finally, while NO decreased both injury-induced proliferation and inflammation in the SHR, it did not return these parameters to levels seen in WKY rats. We conclude that NO is less effective at inhibiting neointimal hyperplasia in the SHR than WKY rats. This may be due to increased scavenging of NO in the SHR, leading to diminished bioavailability of NO. These data will help to develop novel NO-based therapies that will be equally effective in both normotensive and hypertensive patient populations.

Peripheral arterial disease in women.

Peripheral arterial disease (PAD) affects a significant portion of the United States population, and much research has been conducted on identifying populations at risk for PAD, evaluating appropriate diagnostic modalities for PAD, studying the effect of risk factor reduction on PAD progression, and determining the best method of treatment for symptomatic PAD. However, most PAD research and clinical trials have focused on whole populations, or populations consisting mostly of men. Little data exist with respect to PAD in women. The goal of this review is to highlight what is known about gender-related differences for PAD.

Nitric oxide may inhibit neointimal hyperplasia by decreasing isopeptidase T levels and activity in the vasculature.

OBJECTIVE: Isopeptidase T is a cysteine protease deubiquitinating enzyme that hydrolyzes unanchored polyubiquitin chains to free monoubiquitin. Nitric oxide (NO) decreases 26S proteasome activity in vascular smooth muscle cells (VSMCs) and inhibits neointimal hyperplasia in animal models. As NO can cause S-nitrosylation of active-site cysteines, we hypothesize that NO inhibits isopeptidase T activity through S-nitrosylation. Because accumulation of polyubiquitin chains inhibits the 26S proteasome, this may be one mechanism through which NO prevents neointimal hyperplasia. METHODS: To investigate our hypothesis, we examined the effect of NO on isopeptidase T activity, levels, and localization in VSMCs in vitro and in a rat carotid balloon injury model in vivo. RESULTS: NO inhibited recombinant isopeptidase T activity by 82.8% (t = 60 minutes, P < .001 vs control). Dithiothreitol and glutathione (5 mmol/L) both significantly reversed NO-mediated inhibition of isopeptidase T activity (P < .001). NO caused a time-dependent increase in S-nitrosylated isopeptidase T levels in VSMCs, which was reversible with dithiothreitol, indicating that isopeptidase T undergoes reversible S-nitrosylation on exposure to NO in vitro. Although NO did not affect isopeptidase T levels or subcellular localization in VSMCs in vitro, it decreased isopeptidase T levels and increased ubiquitinated proteins after balloon injury in vivo. CONCLUSIONS: Local administration of NO may prevent neointimal hyperplasia by inhibiting isopeptidase T levels and activity in the vasculature, thereby inhibiting the 26S proteasome in VSMCs. These data provide additional mechanistic insights into the ability of NO to prevent neointimal hyperplasia after vascular interventions.

Nitric oxide decreases activity and levels of the 11S proteasome activator PA28 in the vasculature.

The 11S proteasome activator (PA28) binds to the 20S proteasome and increases its ability to degrade small peptides. Expression of PA28 subunits (α, ß, γ) is induced by interferon-γ stimulation. Inflammation plays a role in the development of neointimal hyperplasia, and we have previously shown that nitric oxide (NO) reduces neointimal hyperplasia in animal models and 26S proteasome activity in rat aortic smooth muscle cells (RASMC). Here, we show that PA28 increased 26S proteasome activity in RASMC, as measured by a fluorogenic assay, and the NO donor S-nitroso N-acetylpenicillamine significantly inhibits this activation. This effect was abrogated by the reducing agents dithiothreitol and HgCl(2), suggesting that NO affects the activity of PA28 through S-nitrosylation. NO did not appear to affect PA28 levels or intracellular localization in RASMC in vitro. Three days following rat carotid artery balloon injury, levels of PA28α, ß and γ subunits were decreased compared to uninjured control arteries (n=3/group) in vivo. The NO donor proline NONOate further decreased PA28α, ß and γ levels by 1.9-, 2.3- and 3.4-fold, respectively, compared to uninjured control arteries. Fourteen days following arterial injury, levels of PA28α, ß and γ subunits were increased throughout the arterial wall compared to uninjured control arteries, but were greatest for the α and ß subunits. NO continued to decrease the levels of all three PA28 subunits throughout the arterial wall at this time point. Since the PA28 subunits are involved in the breakdown of peptides during inflammation, PA28 inhibition may be one mechanism by which NO inhibits neointimal hyperplasia.

The role of estrogen receptor α and ß in regulating vascular smooth muscle cell proliferation is based on sex.

BACKGROUND: We previously demonstrated that vascular smooth muscle cells (VSMC) proliferation and development of neointimal hyperplasia as well as the ability of nitric oxide (NO) to inhibit these processes is dependent on sex and hormone status. The aim of this study was to evaluate the role of estrogen receptor (ER) in mediating proliferation in male and female VSMC. MATERIALS AND METHODS: Proliferation was assessed in primary rat aortic male and female VSMC using (3)H-thymidine incorporation in the presence or absence of ER alpha (α) inhibitor methyl-piperidino-pyrazole, the ER beta (ß) inhibitor (R,R)-5,11-Diethyl-5,6,11,12-tetrahydro-2,8-chrysenediol, the combined ERαß inhibitor ICI 182,780, and/or the NO donor DETA/NO. Proliferation was also assessed in primary aortic mouse VSMC harvested from wildtype (WT), ERα knockout (ERα KO), and ERß knockout (ERß KO) mice in the presence or absence of DETA/NO and the ERα, ERß, and ERαß inhibitors. Protein levels were assessed using Western blot analysis. RESULTS: Protein expression of ERα and ERß was present and equal in male and female VSMC, and did not change after exposure to NO. Inhibition of either ERα or ERß had no effect on VSMC proliferation in the presence or absence of NO in either sex. However, inhibition of ERαß in rat VSMC mitigated NO-mediated inhibition in female but not male VSMC (P < 0.05). Evaluation of proliferation in the knockout mice revealed distinct patterns. Male ERαKO and ERßKO VSMC proliferated faster than male WT VSMC (P < 0.05). Female ERßKO proliferated faster than female WT VSMC (P < 0.05), but female ERαKO VSMC proliferated slower than female WT VSMC (P < 0.05). Last, we evaluated the effect of combined inhibition of ERα and ERß in these knockout strains. Combined ERαß inhibition abrogated NO-mediated inhibition of VSMC proliferation in female WT and knockout VSMC (P < 0.05), but not in male VSMC. CONCLUSIONS: These data clearly demonstrate a role for the ER in mediating VSMC proliferation in both sexes. However, these data suggest that the antiproliferative effects of NO may be regulated by the ER in females but not males.